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![Al Viro](/assets/img/avatar_default.png)
* pull ACC_MODE to fs.h; we have several copies all over the place * nightmarish expression calculating f_mode by f_flags deserves a helper too (OPEN_FMODE(flags)) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2943 lines
71 KiB
C
2943 lines
71 KiB
C
/*
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* linux/fs/namei.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* Some corrections by tytso.
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*/
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/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
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* lookup logic.
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*/
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/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/quotaops.h>
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#include <linux/pagemap.h>
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#include <linux/fsnotify.h>
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#include <linux/personality.h>
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#include <linux/security.h>
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#include <linux/ima.h>
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#include <linux/syscalls.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/capability.h>
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#include <linux/file.h>
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#include <linux/fcntl.h>
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#include <linux/device_cgroup.h>
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#include <linux/fs_struct.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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/* [Feb-1997 T. Schoebel-Theuer]
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* Fundamental changes in the pathname lookup mechanisms (namei)
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* were necessary because of omirr. The reason is that omirr needs
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* to know the _real_ pathname, not the user-supplied one, in case
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* of symlinks (and also when transname replacements occur).
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*
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* The new code replaces the old recursive symlink resolution with
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* an iterative one (in case of non-nested symlink chains). It does
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* this with calls to <fs>_follow_link().
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* As a side effect, dir_namei(), _namei() and follow_link() are now
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* replaced with a single function lookup_dentry() that can handle all
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* the special cases of the former code.
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*
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* With the new dcache, the pathname is stored at each inode, at least as
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* long as the refcount of the inode is positive. As a side effect, the
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* size of the dcache depends on the inode cache and thus is dynamic.
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*
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* [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
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* resolution to correspond with current state of the code.
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*
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* Note that the symlink resolution is not *completely* iterative.
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* There is still a significant amount of tail- and mid- recursion in
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* the algorithm. Also, note that <fs>_readlink() is not used in
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* lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
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* may return different results than <fs>_follow_link(). Many virtual
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* filesystems (including /proc) exhibit this behavior.
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*/
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/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
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* New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
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* and the name already exists in form of a symlink, try to create the new
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* name indicated by the symlink. The old code always complained that the
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* name already exists, due to not following the symlink even if its target
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* is nonexistent. The new semantics affects also mknod() and link() when
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* the name is a symlink pointing to a non-existant name.
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*
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* I don't know which semantics is the right one, since I have no access
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* to standards. But I found by trial that HP-UX 9.0 has the full "new"
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* semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
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* "old" one. Personally, I think the new semantics is much more logical.
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* Note that "ln old new" where "new" is a symlink pointing to a non-existing
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* file does succeed in both HP-UX and SunOs, but not in Solaris
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* and in the old Linux semantics.
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*/
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/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
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* semantics. See the comments in "open_namei" and "do_link" below.
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*
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* [10-Sep-98 Alan Modra] Another symlink change.
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*/
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/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
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* inside the path - always follow.
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* in the last component in creation/removal/renaming - never follow.
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* if LOOKUP_FOLLOW passed - follow.
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* if the pathname has trailing slashes - follow.
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* otherwise - don't follow.
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* (applied in that order).
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*
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* [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
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* restored for 2.4. This is the last surviving part of old 4.2BSD bug.
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* During the 2.4 we need to fix the userland stuff depending on it -
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* hopefully we will be able to get rid of that wart in 2.5. So far only
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* XEmacs seems to be relying on it...
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*/
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/*
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* [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
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* implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
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* any extra contention...
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*/
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/* In order to reduce some races, while at the same time doing additional
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* checking and hopefully speeding things up, we copy filenames to the
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* kernel data space before using them..
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*
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* POSIX.1 2.4: an empty pathname is invalid (ENOENT).
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* PATH_MAX includes the nul terminator --RR.
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*/
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static int do_getname(const char __user *filename, char *page)
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{
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int retval;
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unsigned long len = PATH_MAX;
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if (!segment_eq(get_fs(), KERNEL_DS)) {
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if ((unsigned long) filename >= TASK_SIZE)
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return -EFAULT;
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if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
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len = TASK_SIZE - (unsigned long) filename;
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}
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retval = strncpy_from_user(page, filename, len);
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if (retval > 0) {
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if (retval < len)
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return 0;
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return -ENAMETOOLONG;
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} else if (!retval)
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retval = -ENOENT;
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return retval;
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}
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char * getname(const char __user * filename)
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{
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char *tmp, *result;
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result = ERR_PTR(-ENOMEM);
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tmp = __getname();
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if (tmp) {
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int retval = do_getname(filename, tmp);
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result = tmp;
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if (retval < 0) {
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__putname(tmp);
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result = ERR_PTR(retval);
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}
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}
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audit_getname(result);
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return result;
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}
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#ifdef CONFIG_AUDITSYSCALL
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void putname(const char *name)
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{
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if (unlikely(!audit_dummy_context()))
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audit_putname(name);
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else
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__putname(name);
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}
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EXPORT_SYMBOL(putname);
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#endif
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/*
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* This does basic POSIX ACL permission checking
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*/
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static int acl_permission_check(struct inode *inode, int mask,
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int (*check_acl)(struct inode *inode, int mask))
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{
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umode_t mode = inode->i_mode;
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mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
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if (current_fsuid() == inode->i_uid)
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mode >>= 6;
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else {
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if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
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int error = check_acl(inode, mask);
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if (error != -EAGAIN)
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return error;
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}
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if (in_group_p(inode->i_gid))
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mode >>= 3;
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}
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/*
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* If the DACs are ok we don't need any capability check.
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*/
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if ((mask & ~mode) == 0)
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return 0;
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return -EACCES;
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}
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/**
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* generic_permission - check for access rights on a Posix-like filesystem
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* @inode: inode to check access rights for
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
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* @check_acl: optional callback to check for Posix ACLs
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*
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* Used to check for read/write/execute permissions on a file.
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* We use "fsuid" for this, letting us set arbitrary permissions
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* for filesystem access without changing the "normal" uids which
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* are used for other things..
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*/
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int generic_permission(struct inode *inode, int mask,
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int (*check_acl)(struct inode *inode, int mask))
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{
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int ret;
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/*
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* Do the basic POSIX ACL permission checks.
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*/
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ret = acl_permission_check(inode, mask, check_acl);
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if (ret != -EACCES)
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return ret;
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/*
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* Read/write DACs are always overridable.
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* Executable DACs are overridable if at least one exec bit is set.
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*/
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if (!(mask & MAY_EXEC) || execute_ok(inode))
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if (capable(CAP_DAC_OVERRIDE))
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return 0;
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/*
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* Searching includes executable on directories, else just read.
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*/
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if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
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if (capable(CAP_DAC_READ_SEARCH))
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return 0;
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return -EACCES;
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}
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/**
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* inode_permission - check for access rights to a given inode
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* @inode: inode to check permission on
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
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*
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* Used to check for read/write/execute permissions on an inode.
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* We use "fsuid" for this, letting us set arbitrary permissions
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* for filesystem access without changing the "normal" uids which
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* are used for other things.
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*/
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int inode_permission(struct inode *inode, int mask)
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{
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int retval;
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if (mask & MAY_WRITE) {
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umode_t mode = inode->i_mode;
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/*
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* Nobody gets write access to a read-only fs.
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*/
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if (IS_RDONLY(inode) &&
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(S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
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return -EROFS;
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/*
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* Nobody gets write access to an immutable file.
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*/
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if (IS_IMMUTABLE(inode))
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return -EACCES;
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}
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if (inode->i_op->permission)
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retval = inode->i_op->permission(inode, mask);
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else
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retval = generic_permission(inode, mask, inode->i_op->check_acl);
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if (retval)
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return retval;
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retval = devcgroup_inode_permission(inode, mask);
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if (retval)
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return retval;
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return security_inode_permission(inode,
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mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND));
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}
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/**
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* file_permission - check for additional access rights to a given file
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* @file: file to check access rights for
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* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
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*
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* Used to check for read/write/execute permissions on an already opened
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* file.
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*
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* Note:
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* Do not use this function in new code. All access checks should
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* be done using inode_permission().
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*/
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int file_permission(struct file *file, int mask)
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{
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return inode_permission(file->f_path.dentry->d_inode, mask);
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}
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/*
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* get_write_access() gets write permission for a file.
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* put_write_access() releases this write permission.
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* This is used for regular files.
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* We cannot support write (and maybe mmap read-write shared) accesses and
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* MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
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* can have the following values:
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* 0: no writers, no VM_DENYWRITE mappings
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* < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
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* > 0: (i_writecount) users are writing to the file.
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*
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* Normally we operate on that counter with atomic_{inc,dec} and it's safe
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* except for the cases where we don't hold i_writecount yet. Then we need to
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* use {get,deny}_write_access() - these functions check the sign and refuse
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* to do the change if sign is wrong. Exclusion between them is provided by
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* the inode->i_lock spinlock.
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*/
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int get_write_access(struct inode * inode)
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{
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spin_lock(&inode->i_lock);
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if (atomic_read(&inode->i_writecount) < 0) {
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spin_unlock(&inode->i_lock);
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return -ETXTBSY;
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}
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atomic_inc(&inode->i_writecount);
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spin_unlock(&inode->i_lock);
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return 0;
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}
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int deny_write_access(struct file * file)
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{
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struct inode *inode = file->f_path.dentry->d_inode;
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spin_lock(&inode->i_lock);
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if (atomic_read(&inode->i_writecount) > 0) {
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spin_unlock(&inode->i_lock);
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return -ETXTBSY;
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}
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atomic_dec(&inode->i_writecount);
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spin_unlock(&inode->i_lock);
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return 0;
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}
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/**
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* path_get - get a reference to a path
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* @path: path to get the reference to
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*
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* Given a path increment the reference count to the dentry and the vfsmount.
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*/
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void path_get(struct path *path)
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{
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mntget(path->mnt);
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dget(path->dentry);
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}
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EXPORT_SYMBOL(path_get);
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/**
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* path_put - put a reference to a path
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* @path: path to put the reference to
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*
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* Given a path decrement the reference count to the dentry and the vfsmount.
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*/
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void path_put(struct path *path)
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{
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dput(path->dentry);
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mntput(path->mnt);
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}
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EXPORT_SYMBOL(path_put);
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/**
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* release_open_intent - free up open intent resources
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* @nd: pointer to nameidata
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*/
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void release_open_intent(struct nameidata *nd)
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{
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if (nd->intent.open.file->f_path.dentry == NULL)
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put_filp(nd->intent.open.file);
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else
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fput(nd->intent.open.file);
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}
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static inline struct dentry *
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do_revalidate(struct dentry *dentry, struct nameidata *nd)
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{
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int status = dentry->d_op->d_revalidate(dentry, nd);
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if (unlikely(status <= 0)) {
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/*
|
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* The dentry failed validation.
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* If d_revalidate returned 0 attempt to invalidate
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* the dentry otherwise d_revalidate is asking us
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* to return a fail status.
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*/
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if (!status) {
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if (!d_invalidate(dentry)) {
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dput(dentry);
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dentry = NULL;
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}
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} else {
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dput(dentry);
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dentry = ERR_PTR(status);
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}
|
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}
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return dentry;
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}
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|
|
|
/*
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* force_reval_path - force revalidation of a dentry
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*
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* In some situations the path walking code will trust dentries without
|
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* revalidating them. This causes problems for filesystems that depend on
|
|
* d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set
|
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* (which indicates that it's possible for the dentry to go stale), force
|
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* a d_revalidate call before proceeding.
|
|
*
|
|
* Returns 0 if the revalidation was successful. If the revalidation fails,
|
|
* either return the error returned by d_revalidate or -ESTALE if the
|
|
* revalidation it just returned 0. If d_revalidate returns 0, we attempt to
|
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* invalidate the dentry. It's up to the caller to handle putting references
|
|
* to the path if necessary.
|
|
*/
|
|
static int
|
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force_reval_path(struct path *path, struct nameidata *nd)
|
|
{
|
|
int status;
|
|
struct dentry *dentry = path->dentry;
|
|
|
|
/*
|
|
* only check on filesystems where it's possible for the dentry to
|
|
* become stale. It's assumed that if this flag is set then the
|
|
* d_revalidate op will also be defined.
|
|
*/
|
|
if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))
|
|
return 0;
|
|
|
|
status = dentry->d_op->d_revalidate(dentry, nd);
|
|
if (status > 0)
|
|
return 0;
|
|
|
|
if (!status) {
|
|
d_invalidate(dentry);
|
|
status = -ESTALE;
|
|
}
|
|
return status;
|
|
}
|
|
|
|
/*
|
|
* Short-cut version of permission(), for calling on directories
|
|
* during pathname resolution. Combines parts of permission()
|
|
* and generic_permission(), and tests ONLY for MAY_EXEC permission.
|
|
*
|
|
* If appropriate, check DAC only. If not appropriate, or
|
|
* short-cut DAC fails, then call ->permission() to do more
|
|
* complete permission check.
|
|
*/
|
|
static int exec_permission(struct inode *inode)
|
|
{
|
|
int ret;
|
|
|
|
if (inode->i_op->permission) {
|
|
ret = inode->i_op->permission(inode, MAY_EXEC);
|
|
if (!ret)
|
|
goto ok;
|
|
return ret;
|
|
}
|
|
ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl);
|
|
if (!ret)
|
|
goto ok;
|
|
|
|
if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH))
|
|
goto ok;
|
|
|
|
return ret;
|
|
ok:
|
|
return security_inode_permission(inode, MAY_EXEC);
|
|
}
|
|
|
|
static __always_inline void set_root(struct nameidata *nd)
|
|
{
|
|
if (!nd->root.mnt) {
|
|
struct fs_struct *fs = current->fs;
|
|
read_lock(&fs->lock);
|
|
nd->root = fs->root;
|
|
path_get(&nd->root);
|
|
read_unlock(&fs->lock);
|
|
}
|
|
}
|
|
|
|
static int link_path_walk(const char *, struct nameidata *);
|
|
|
|
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
|
|
{
|
|
int res = 0;
|
|
char *name;
|
|
if (IS_ERR(link))
|
|
goto fail;
|
|
|
|
if (*link == '/') {
|
|
set_root(nd);
|
|
path_put(&nd->path);
|
|
nd->path = nd->root;
|
|
path_get(&nd->root);
|
|
}
|
|
|
|
res = link_path_walk(link, nd);
|
|
if (nd->depth || res || nd->last_type!=LAST_NORM)
|
|
return res;
|
|
/*
|
|
* If it is an iterative symlinks resolution in open_namei() we
|
|
* have to copy the last component. And all that crap because of
|
|
* bloody create() on broken symlinks. Furrfu...
|
|
*/
|
|
name = __getname();
|
|
if (unlikely(!name)) {
|
|
path_put(&nd->path);
|
|
return -ENOMEM;
|
|
}
|
|
strcpy(name, nd->last.name);
|
|
nd->last.name = name;
|
|
return 0;
|
|
fail:
|
|
path_put(&nd->path);
|
|
return PTR_ERR(link);
|
|
}
|
|
|
|
static void path_put_conditional(struct path *path, struct nameidata *nd)
|
|
{
|
|
dput(path->dentry);
|
|
if (path->mnt != nd->path.mnt)
|
|
mntput(path->mnt);
|
|
}
|
|
|
|
static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
|
|
{
|
|
dput(nd->path.dentry);
|
|
if (nd->path.mnt != path->mnt)
|
|
mntput(nd->path.mnt);
|
|
nd->path.mnt = path->mnt;
|
|
nd->path.dentry = path->dentry;
|
|
}
|
|
|
|
static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
|
|
{
|
|
int error;
|
|
void *cookie;
|
|
struct dentry *dentry = path->dentry;
|
|
|
|
touch_atime(path->mnt, dentry);
|
|
nd_set_link(nd, NULL);
|
|
|
|
if (path->mnt != nd->path.mnt) {
|
|
path_to_nameidata(path, nd);
|
|
dget(dentry);
|
|
}
|
|
mntget(path->mnt);
|
|
cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
|
|
error = PTR_ERR(cookie);
|
|
if (!IS_ERR(cookie)) {
|
|
char *s = nd_get_link(nd);
|
|
error = 0;
|
|
if (s)
|
|
error = __vfs_follow_link(nd, s);
|
|
else if (nd->last_type == LAST_BIND) {
|
|
error = force_reval_path(&nd->path, nd);
|
|
if (error)
|
|
path_put(&nd->path);
|
|
}
|
|
if (dentry->d_inode->i_op->put_link)
|
|
dentry->d_inode->i_op->put_link(dentry, nd, cookie);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* This limits recursive symlink follows to 8, while
|
|
* limiting consecutive symlinks to 40.
|
|
*
|
|
* Without that kind of total limit, nasty chains of consecutive
|
|
* symlinks can cause almost arbitrarily long lookups.
|
|
*/
|
|
static inline int do_follow_link(struct path *path, struct nameidata *nd)
|
|
{
|
|
int err = -ELOOP;
|
|
if (current->link_count >= MAX_NESTED_LINKS)
|
|
goto loop;
|
|
if (current->total_link_count >= 40)
|
|
goto loop;
|
|
BUG_ON(nd->depth >= MAX_NESTED_LINKS);
|
|
cond_resched();
|
|
err = security_inode_follow_link(path->dentry, nd);
|
|
if (err)
|
|
goto loop;
|
|
current->link_count++;
|
|
current->total_link_count++;
|
|
nd->depth++;
|
|
err = __do_follow_link(path, nd);
|
|
path_put(path);
|
|
current->link_count--;
|
|
nd->depth--;
|
|
return err;
|
|
loop:
|
|
path_put_conditional(path, nd);
|
|
path_put(&nd->path);
|
|
return err;
|
|
}
|
|
|
|
int follow_up(struct path *path)
|
|
{
|
|
struct vfsmount *parent;
|
|
struct dentry *mountpoint;
|
|
spin_lock(&vfsmount_lock);
|
|
parent = path->mnt->mnt_parent;
|
|
if (parent == path->mnt) {
|
|
spin_unlock(&vfsmount_lock);
|
|
return 0;
|
|
}
|
|
mntget(parent);
|
|
mountpoint = dget(path->mnt->mnt_mountpoint);
|
|
spin_unlock(&vfsmount_lock);
|
|
dput(path->dentry);
|
|
path->dentry = mountpoint;
|
|
mntput(path->mnt);
|
|
path->mnt = parent;
|
|
return 1;
|
|
}
|
|
|
|
/* no need for dcache_lock, as serialization is taken care in
|
|
* namespace.c
|
|
*/
|
|
static int __follow_mount(struct path *path)
|
|
{
|
|
int res = 0;
|
|
while (d_mountpoint(path->dentry)) {
|
|
struct vfsmount *mounted = lookup_mnt(path);
|
|
if (!mounted)
|
|
break;
|
|
dput(path->dentry);
|
|
if (res)
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
res = 1;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
static void follow_mount(struct path *path)
|
|
{
|
|
while (d_mountpoint(path->dentry)) {
|
|
struct vfsmount *mounted = lookup_mnt(path);
|
|
if (!mounted)
|
|
break;
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
}
|
|
}
|
|
|
|
/* no need for dcache_lock, as serialization is taken care in
|
|
* namespace.c
|
|
*/
|
|
int follow_down(struct path *path)
|
|
{
|
|
struct vfsmount *mounted;
|
|
|
|
mounted = lookup_mnt(path);
|
|
if (mounted) {
|
|
dput(path->dentry);
|
|
mntput(path->mnt);
|
|
path->mnt = mounted;
|
|
path->dentry = dget(mounted->mnt_root);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static __always_inline void follow_dotdot(struct nameidata *nd)
|
|
{
|
|
set_root(nd);
|
|
|
|
while(1) {
|
|
struct vfsmount *parent;
|
|
struct dentry *old = nd->path.dentry;
|
|
|
|
if (nd->path.dentry == nd->root.dentry &&
|
|
nd->path.mnt == nd->root.mnt) {
|
|
break;
|
|
}
|
|
spin_lock(&dcache_lock);
|
|
if (nd->path.dentry != nd->path.mnt->mnt_root) {
|
|
nd->path.dentry = dget(nd->path.dentry->d_parent);
|
|
spin_unlock(&dcache_lock);
|
|
dput(old);
|
|
break;
|
|
}
|
|
spin_unlock(&dcache_lock);
|
|
spin_lock(&vfsmount_lock);
|
|
parent = nd->path.mnt->mnt_parent;
|
|
if (parent == nd->path.mnt) {
|
|
spin_unlock(&vfsmount_lock);
|
|
break;
|
|
}
|
|
mntget(parent);
|
|
nd->path.dentry = dget(nd->path.mnt->mnt_mountpoint);
|
|
spin_unlock(&vfsmount_lock);
|
|
dput(old);
|
|
mntput(nd->path.mnt);
|
|
nd->path.mnt = parent;
|
|
}
|
|
follow_mount(&nd->path);
|
|
}
|
|
|
|
/*
|
|
* It's more convoluted than I'd like it to be, but... it's still fairly
|
|
* small and for now I'd prefer to have fast path as straight as possible.
|
|
* It _is_ time-critical.
|
|
*/
|
|
static int do_lookup(struct nameidata *nd, struct qstr *name,
|
|
struct path *path)
|
|
{
|
|
struct vfsmount *mnt = nd->path.mnt;
|
|
struct dentry *dentry, *parent;
|
|
struct inode *dir;
|
|
/*
|
|
* See if the low-level filesystem might want
|
|
* to use its own hash..
|
|
*/
|
|
if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) {
|
|
int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name);
|
|
if (err < 0)
|
|
return err;
|
|
}
|
|
|
|
dentry = __d_lookup(nd->path.dentry, name);
|
|
if (!dentry)
|
|
goto need_lookup;
|
|
if (dentry->d_op && dentry->d_op->d_revalidate)
|
|
goto need_revalidate;
|
|
done:
|
|
path->mnt = mnt;
|
|
path->dentry = dentry;
|
|
__follow_mount(path);
|
|
return 0;
|
|
|
|
need_lookup:
|
|
parent = nd->path.dentry;
|
|
dir = parent->d_inode;
|
|
|
|
mutex_lock(&dir->i_mutex);
|
|
/*
|
|
* First re-do the cached lookup just in case it was created
|
|
* while we waited for the directory semaphore..
|
|
*
|
|
* FIXME! This could use version numbering or similar to
|
|
* avoid unnecessary cache lookups.
|
|
*
|
|
* The "dcache_lock" is purely to protect the RCU list walker
|
|
* from concurrent renames at this point (we mustn't get false
|
|
* negatives from the RCU list walk here, unlike the optimistic
|
|
* fast walk).
|
|
*
|
|
* so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
|
|
*/
|
|
dentry = d_lookup(parent, name);
|
|
if (!dentry) {
|
|
struct dentry *new;
|
|
|
|
/* Don't create child dentry for a dead directory. */
|
|
dentry = ERR_PTR(-ENOENT);
|
|
if (IS_DEADDIR(dir))
|
|
goto out_unlock;
|
|
|
|
new = d_alloc(parent, name);
|
|
dentry = ERR_PTR(-ENOMEM);
|
|
if (new) {
|
|
dentry = dir->i_op->lookup(dir, new, nd);
|
|
if (dentry)
|
|
dput(new);
|
|
else
|
|
dentry = new;
|
|
}
|
|
out_unlock:
|
|
mutex_unlock(&dir->i_mutex);
|
|
if (IS_ERR(dentry))
|
|
goto fail;
|
|
goto done;
|
|
}
|
|
|
|
/*
|
|
* Uhhuh! Nasty case: the cache was re-populated while
|
|
* we waited on the semaphore. Need to revalidate.
|
|
*/
|
|
mutex_unlock(&dir->i_mutex);
|
|
if (dentry->d_op && dentry->d_op->d_revalidate) {
|
|
dentry = do_revalidate(dentry, nd);
|
|
if (!dentry)
|
|
dentry = ERR_PTR(-ENOENT);
|
|
}
|
|
if (IS_ERR(dentry))
|
|
goto fail;
|
|
goto done;
|
|
|
|
need_revalidate:
|
|
dentry = do_revalidate(dentry, nd);
|
|
if (!dentry)
|
|
goto need_lookup;
|
|
if (IS_ERR(dentry))
|
|
goto fail;
|
|
goto done;
|
|
|
|
fail:
|
|
return PTR_ERR(dentry);
|
|
}
|
|
|
|
/*
|
|
* Name resolution.
|
|
* This is the basic name resolution function, turning a pathname into
|
|
* the final dentry. We expect 'base' to be positive and a directory.
|
|
*
|
|
* Returns 0 and nd will have valid dentry and mnt on success.
|
|
* Returns error and drops reference to input namei data on failure.
|
|
*/
|
|
static int link_path_walk(const char *name, struct nameidata *nd)
|
|
{
|
|
struct path next;
|
|
struct inode *inode;
|
|
int err;
|
|
unsigned int lookup_flags = nd->flags;
|
|
|
|
while (*name=='/')
|
|
name++;
|
|
if (!*name)
|
|
goto return_reval;
|
|
|
|
inode = nd->path.dentry->d_inode;
|
|
if (nd->depth)
|
|
lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
|
|
|
|
/* At this point we know we have a real path component. */
|
|
for(;;) {
|
|
unsigned long hash;
|
|
struct qstr this;
|
|
unsigned int c;
|
|
|
|
nd->flags |= LOOKUP_CONTINUE;
|
|
err = exec_permission(inode);
|
|
if (err)
|
|
break;
|
|
|
|
this.name = name;
|
|
c = *(const unsigned char *)name;
|
|
|
|
hash = init_name_hash();
|
|
do {
|
|
name++;
|
|
hash = partial_name_hash(c, hash);
|
|
c = *(const unsigned char *)name;
|
|
} while (c && (c != '/'));
|
|
this.len = name - (const char *) this.name;
|
|
this.hash = end_name_hash(hash);
|
|
|
|
/* remove trailing slashes? */
|
|
if (!c)
|
|
goto last_component;
|
|
while (*++name == '/');
|
|
if (!*name)
|
|
goto last_with_slashes;
|
|
|
|
/*
|
|
* "." and ".." are special - ".." especially so because it has
|
|
* to be able to know about the current root directory and
|
|
* parent relationships.
|
|
*/
|
|
if (this.name[0] == '.') switch (this.len) {
|
|
default:
|
|
break;
|
|
case 2:
|
|
if (this.name[1] != '.')
|
|
break;
|
|
follow_dotdot(nd);
|
|
inode = nd->path.dentry->d_inode;
|
|
/* fallthrough */
|
|
case 1:
|
|
continue;
|
|
}
|
|
/* This does the actual lookups.. */
|
|
err = do_lookup(nd, &this, &next);
|
|
if (err)
|
|
break;
|
|
|
|
err = -ENOENT;
|
|
inode = next.dentry->d_inode;
|
|
if (!inode)
|
|
goto out_dput;
|
|
|
|
if (inode->i_op->follow_link) {
|
|
err = do_follow_link(&next, nd);
|
|
if (err)
|
|
goto return_err;
|
|
err = -ENOENT;
|
|
inode = nd->path.dentry->d_inode;
|
|
if (!inode)
|
|
break;
|
|
} else
|
|
path_to_nameidata(&next, nd);
|
|
err = -ENOTDIR;
|
|
if (!inode->i_op->lookup)
|
|
break;
|
|
continue;
|
|
/* here ends the main loop */
|
|
|
|
last_with_slashes:
|
|
lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
last_component:
|
|
/* Clear LOOKUP_CONTINUE iff it was previously unset */
|
|
nd->flags &= lookup_flags | ~LOOKUP_CONTINUE;
|
|
if (lookup_flags & LOOKUP_PARENT)
|
|
goto lookup_parent;
|
|
if (this.name[0] == '.') switch (this.len) {
|
|
default:
|
|
break;
|
|
case 2:
|
|
if (this.name[1] != '.')
|
|
break;
|
|
follow_dotdot(nd);
|
|
inode = nd->path.dentry->d_inode;
|
|
/* fallthrough */
|
|
case 1:
|
|
goto return_reval;
|
|
}
|
|
err = do_lookup(nd, &this, &next);
|
|
if (err)
|
|
break;
|
|
inode = next.dentry->d_inode;
|
|
if ((lookup_flags & LOOKUP_FOLLOW)
|
|
&& inode && inode->i_op->follow_link) {
|
|
err = do_follow_link(&next, nd);
|
|
if (err)
|
|
goto return_err;
|
|
inode = nd->path.dentry->d_inode;
|
|
} else
|
|
path_to_nameidata(&next, nd);
|
|
err = -ENOENT;
|
|
if (!inode)
|
|
break;
|
|
if (lookup_flags & LOOKUP_DIRECTORY) {
|
|
err = -ENOTDIR;
|
|
if (!inode->i_op->lookup)
|
|
break;
|
|
}
|
|
goto return_base;
|
|
lookup_parent:
|
|
nd->last = this;
|
|
nd->last_type = LAST_NORM;
|
|
if (this.name[0] != '.')
|
|
goto return_base;
|
|
if (this.len == 1)
|
|
nd->last_type = LAST_DOT;
|
|
else if (this.len == 2 && this.name[1] == '.')
|
|
nd->last_type = LAST_DOTDOT;
|
|
else
|
|
goto return_base;
|
|
return_reval:
|
|
/*
|
|
* We bypassed the ordinary revalidation routines.
|
|
* We may need to check the cached dentry for staleness.
|
|
*/
|
|
if (nd->path.dentry && nd->path.dentry->d_sb &&
|
|
(nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) {
|
|
err = -ESTALE;
|
|
/* Note: we do not d_invalidate() */
|
|
if (!nd->path.dentry->d_op->d_revalidate(
|
|
nd->path.dentry, nd))
|
|
break;
|
|
}
|
|
return_base:
|
|
return 0;
|
|
out_dput:
|
|
path_put_conditional(&next, nd);
|
|
break;
|
|
}
|
|
path_put(&nd->path);
|
|
return_err:
|
|
return err;
|
|
}
|
|
|
|
static int path_walk(const char *name, struct nameidata *nd)
|
|
{
|
|
struct path save = nd->path;
|
|
int result;
|
|
|
|
current->total_link_count = 0;
|
|
|
|
/* make sure the stuff we saved doesn't go away */
|
|
path_get(&save);
|
|
|
|
result = link_path_walk(name, nd);
|
|
if (result == -ESTALE) {
|
|
/* nd->path had been dropped */
|
|
current->total_link_count = 0;
|
|
nd->path = save;
|
|
path_get(&nd->path);
|
|
nd->flags |= LOOKUP_REVAL;
|
|
result = link_path_walk(name, nd);
|
|
}
|
|
|
|
path_put(&save);
|
|
|
|
return result;
|
|
}
|
|
|
|
static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd)
|
|
{
|
|
int retval = 0;
|
|
int fput_needed;
|
|
struct file *file;
|
|
|
|
nd->last_type = LAST_ROOT; /* if there are only slashes... */
|
|
nd->flags = flags;
|
|
nd->depth = 0;
|
|
nd->root.mnt = NULL;
|
|
|
|
if (*name=='/') {
|
|
set_root(nd);
|
|
nd->path = nd->root;
|
|
path_get(&nd->root);
|
|
} else if (dfd == AT_FDCWD) {
|
|
struct fs_struct *fs = current->fs;
|
|
read_lock(&fs->lock);
|
|
nd->path = fs->pwd;
|
|
path_get(&fs->pwd);
|
|
read_unlock(&fs->lock);
|
|
} else {
|
|
struct dentry *dentry;
|
|
|
|
file = fget_light(dfd, &fput_needed);
|
|
retval = -EBADF;
|
|
if (!file)
|
|
goto out_fail;
|
|
|
|
dentry = file->f_path.dentry;
|
|
|
|
retval = -ENOTDIR;
|
|
if (!S_ISDIR(dentry->d_inode->i_mode))
|
|
goto fput_fail;
|
|
|
|
retval = file_permission(file, MAY_EXEC);
|
|
if (retval)
|
|
goto fput_fail;
|
|
|
|
nd->path = file->f_path;
|
|
path_get(&file->f_path);
|
|
|
|
fput_light(file, fput_needed);
|
|
}
|
|
return 0;
|
|
|
|
fput_fail:
|
|
fput_light(file, fput_needed);
|
|
out_fail:
|
|
return retval;
|
|
}
|
|
|
|
/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
|
|
static int do_path_lookup(int dfd, const char *name,
|
|
unsigned int flags, struct nameidata *nd)
|
|
{
|
|
int retval = path_init(dfd, name, flags, nd);
|
|
if (!retval)
|
|
retval = path_walk(name, nd);
|
|
if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
|
|
nd->path.dentry->d_inode))
|
|
audit_inode(name, nd->path.dentry);
|
|
if (nd->root.mnt) {
|
|
path_put(&nd->root);
|
|
nd->root.mnt = NULL;
|
|
}
|
|
return retval;
|
|
}
|
|
|
|
int path_lookup(const char *name, unsigned int flags,
|
|
struct nameidata *nd)
|
|
{
|
|
return do_path_lookup(AT_FDCWD, name, flags, nd);
|
|
}
|
|
|
|
int kern_path(const char *name, unsigned int flags, struct path *path)
|
|
{
|
|
struct nameidata nd;
|
|
int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
|
|
if (!res)
|
|
*path = nd.path;
|
|
return res;
|
|
}
|
|
|
|
/**
|
|
* vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
|
|
* @dentry: pointer to dentry of the base directory
|
|
* @mnt: pointer to vfs mount of the base directory
|
|
* @name: pointer to file name
|
|
* @flags: lookup flags
|
|
* @nd: pointer to nameidata
|
|
*/
|
|
int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *name, unsigned int flags,
|
|
struct nameidata *nd)
|
|
{
|
|
int retval;
|
|
|
|
/* same as do_path_lookup */
|
|
nd->last_type = LAST_ROOT;
|
|
nd->flags = flags;
|
|
nd->depth = 0;
|
|
|
|
nd->path.dentry = dentry;
|
|
nd->path.mnt = mnt;
|
|
path_get(&nd->path);
|
|
nd->root = nd->path;
|
|
path_get(&nd->root);
|
|
|
|
retval = path_walk(name, nd);
|
|
if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry &&
|
|
nd->path.dentry->d_inode))
|
|
audit_inode(name, nd->path.dentry);
|
|
|
|
path_put(&nd->root);
|
|
nd->root.mnt = NULL;
|
|
|
|
return retval;
|
|
}
|
|
|
|
static struct dentry *__lookup_hash(struct qstr *name,
|
|
struct dentry *base, struct nameidata *nd)
|
|
{
|
|
struct dentry *dentry;
|
|
struct inode *inode;
|
|
int err;
|
|
|
|
inode = base->d_inode;
|
|
|
|
/*
|
|
* See if the low-level filesystem might want
|
|
* to use its own hash..
|
|
*/
|
|
if (base->d_op && base->d_op->d_hash) {
|
|
err = base->d_op->d_hash(base, name);
|
|
dentry = ERR_PTR(err);
|
|
if (err < 0)
|
|
goto out;
|
|
}
|
|
|
|
dentry = __d_lookup(base, name);
|
|
|
|
/* lockess __d_lookup may fail due to concurrent d_move()
|
|
* in some unrelated directory, so try with d_lookup
|
|
*/
|
|
if (!dentry)
|
|
dentry = d_lookup(base, name);
|
|
|
|
if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
|
|
dentry = do_revalidate(dentry, nd);
|
|
|
|
if (!dentry) {
|
|
struct dentry *new;
|
|
|
|
/* Don't create child dentry for a dead directory. */
|
|
dentry = ERR_PTR(-ENOENT);
|
|
if (IS_DEADDIR(inode))
|
|
goto out;
|
|
|
|
new = d_alloc(base, name);
|
|
dentry = ERR_PTR(-ENOMEM);
|
|
if (!new)
|
|
goto out;
|
|
dentry = inode->i_op->lookup(inode, new, nd);
|
|
if (!dentry)
|
|
dentry = new;
|
|
else
|
|
dput(new);
|
|
}
|
|
out:
|
|
return dentry;
|
|
}
|
|
|
|
/*
|
|
* Restricted form of lookup. Doesn't follow links, single-component only,
|
|
* needs parent already locked. Doesn't follow mounts.
|
|
* SMP-safe.
|
|
*/
|
|
static struct dentry *lookup_hash(struct nameidata *nd)
|
|
{
|
|
int err;
|
|
|
|
err = exec_permission(nd->path.dentry->d_inode);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
return __lookup_hash(&nd->last, nd->path.dentry, nd);
|
|
}
|
|
|
|
static int __lookup_one_len(const char *name, struct qstr *this,
|
|
struct dentry *base, int len)
|
|
{
|
|
unsigned long hash;
|
|
unsigned int c;
|
|
|
|
this->name = name;
|
|
this->len = len;
|
|
if (!len)
|
|
return -EACCES;
|
|
|
|
hash = init_name_hash();
|
|
while (len--) {
|
|
c = *(const unsigned char *)name++;
|
|
if (c == '/' || c == '\0')
|
|
return -EACCES;
|
|
hash = partial_name_hash(c, hash);
|
|
}
|
|
this->hash = end_name_hash(hash);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* lookup_one_len - filesystem helper to lookup single pathname component
|
|
* @name: pathname component to lookup
|
|
* @base: base directory to lookup from
|
|
* @len: maximum length @len should be interpreted to
|
|
*
|
|
* Note that this routine is purely a helper for filesystem usage and should
|
|
* not be called by generic code. Also note that by using this function the
|
|
* nameidata argument is passed to the filesystem methods and a filesystem
|
|
* using this helper needs to be prepared for that.
|
|
*/
|
|
struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
|
|
{
|
|
int err;
|
|
struct qstr this;
|
|
|
|
WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
|
|
|
|
err = __lookup_one_len(name, &this, base, len);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
err = exec_permission(base->d_inode);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
return __lookup_hash(&this, base, NULL);
|
|
}
|
|
|
|
int user_path_at(int dfd, const char __user *name, unsigned flags,
|
|
struct path *path)
|
|
{
|
|
struct nameidata nd;
|
|
char *tmp = getname(name);
|
|
int err = PTR_ERR(tmp);
|
|
if (!IS_ERR(tmp)) {
|
|
|
|
BUG_ON(flags & LOOKUP_PARENT);
|
|
|
|
err = do_path_lookup(dfd, tmp, flags, &nd);
|
|
putname(tmp);
|
|
if (!err)
|
|
*path = nd.path;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int user_path_parent(int dfd, const char __user *path,
|
|
struct nameidata *nd, char **name)
|
|
{
|
|
char *s = getname(path);
|
|
int error;
|
|
|
|
if (IS_ERR(s))
|
|
return PTR_ERR(s);
|
|
|
|
error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
|
|
if (error)
|
|
putname(s);
|
|
else
|
|
*name = s;
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* It's inline, so penalty for filesystems that don't use sticky bit is
|
|
* minimal.
|
|
*/
|
|
static inline int check_sticky(struct inode *dir, struct inode *inode)
|
|
{
|
|
uid_t fsuid = current_fsuid();
|
|
|
|
if (!(dir->i_mode & S_ISVTX))
|
|
return 0;
|
|
if (inode->i_uid == fsuid)
|
|
return 0;
|
|
if (dir->i_uid == fsuid)
|
|
return 0;
|
|
return !capable(CAP_FOWNER);
|
|
}
|
|
|
|
/*
|
|
* Check whether we can remove a link victim from directory dir, check
|
|
* whether the type of victim is right.
|
|
* 1. We can't do it if dir is read-only (done in permission())
|
|
* 2. We should have write and exec permissions on dir
|
|
* 3. We can't remove anything from append-only dir
|
|
* 4. We can't do anything with immutable dir (done in permission())
|
|
* 5. If the sticky bit on dir is set we should either
|
|
* a. be owner of dir, or
|
|
* b. be owner of victim, or
|
|
* c. have CAP_FOWNER capability
|
|
* 6. If the victim is append-only or immutable we can't do antyhing with
|
|
* links pointing to it.
|
|
* 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
|
|
* 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
|
|
* 9. We can't remove a root or mountpoint.
|
|
* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
|
|
* nfs_async_unlink().
|
|
*/
|
|
static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
|
|
{
|
|
int error;
|
|
|
|
if (!victim->d_inode)
|
|
return -ENOENT;
|
|
|
|
BUG_ON(victim->d_parent->d_inode != dir);
|
|
audit_inode_child(victim->d_name.name, victim, dir);
|
|
|
|
error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
|
|
if (error)
|
|
return error;
|
|
if (IS_APPEND(dir))
|
|
return -EPERM;
|
|
if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
|
|
IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
|
|
return -EPERM;
|
|
if (isdir) {
|
|
if (!S_ISDIR(victim->d_inode->i_mode))
|
|
return -ENOTDIR;
|
|
if (IS_ROOT(victim))
|
|
return -EBUSY;
|
|
} else if (S_ISDIR(victim->d_inode->i_mode))
|
|
return -EISDIR;
|
|
if (IS_DEADDIR(dir))
|
|
return -ENOENT;
|
|
if (victim->d_flags & DCACHE_NFSFS_RENAMED)
|
|
return -EBUSY;
|
|
return 0;
|
|
}
|
|
|
|
/* Check whether we can create an object with dentry child in directory
|
|
* dir.
|
|
* 1. We can't do it if child already exists (open has special treatment for
|
|
* this case, but since we are inlined it's OK)
|
|
* 2. We can't do it if dir is read-only (done in permission())
|
|
* 3. We should have write and exec permissions on dir
|
|
* 4. We can't do it if dir is immutable (done in permission())
|
|
*/
|
|
static inline int may_create(struct inode *dir, struct dentry *child)
|
|
{
|
|
if (child->d_inode)
|
|
return -EEXIST;
|
|
if (IS_DEADDIR(dir))
|
|
return -ENOENT;
|
|
return inode_permission(dir, MAY_WRITE | MAY_EXEC);
|
|
}
|
|
|
|
/*
|
|
* O_DIRECTORY translates into forcing a directory lookup.
|
|
*/
|
|
static inline int lookup_flags(unsigned int f)
|
|
{
|
|
unsigned long retval = LOOKUP_FOLLOW;
|
|
|
|
if (f & O_NOFOLLOW)
|
|
retval &= ~LOOKUP_FOLLOW;
|
|
|
|
if (f & O_DIRECTORY)
|
|
retval |= LOOKUP_DIRECTORY;
|
|
|
|
return retval;
|
|
}
|
|
|
|
/*
|
|
* p1 and p2 should be directories on the same fs.
|
|
*/
|
|
struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
struct dentry *p;
|
|
|
|
if (p1 == p2) {
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
return NULL;
|
|
}
|
|
|
|
mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
|
|
|
|
p = d_ancestor(p2, p1);
|
|
if (p) {
|
|
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
|
|
return p;
|
|
}
|
|
|
|
p = d_ancestor(p1, p2);
|
|
if (p) {
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
|
|
return p;
|
|
}
|
|
|
|
mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
|
|
return NULL;
|
|
}
|
|
|
|
void unlock_rename(struct dentry *p1, struct dentry *p2)
|
|
{
|
|
mutex_unlock(&p1->d_inode->i_mutex);
|
|
if (p1 != p2) {
|
|
mutex_unlock(&p2->d_inode->i_mutex);
|
|
mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
|
|
}
|
|
}
|
|
|
|
int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
|
|
struct nameidata *nd)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->create)
|
|
return -EACCES; /* shouldn't it be ENOSYS? */
|
|
mode &= S_IALLUGO;
|
|
mode |= S_IFREG;
|
|
error = security_inode_create(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
vfs_dq_init(dir);
|
|
error = dir->i_op->create(dir, dentry, mode, nd);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
int may_open(struct path *path, int acc_mode, int flag)
|
|
{
|
|
struct dentry *dentry = path->dentry;
|
|
struct inode *inode = dentry->d_inode;
|
|
int error;
|
|
|
|
if (!inode)
|
|
return -ENOENT;
|
|
|
|
switch (inode->i_mode & S_IFMT) {
|
|
case S_IFLNK:
|
|
return -ELOOP;
|
|
case S_IFDIR:
|
|
if (acc_mode & MAY_WRITE)
|
|
return -EISDIR;
|
|
break;
|
|
case S_IFBLK:
|
|
case S_IFCHR:
|
|
if (path->mnt->mnt_flags & MNT_NODEV)
|
|
return -EACCES;
|
|
/*FALLTHRU*/
|
|
case S_IFIFO:
|
|
case S_IFSOCK:
|
|
flag &= ~O_TRUNC;
|
|
break;
|
|
}
|
|
|
|
error = inode_permission(inode, acc_mode);
|
|
if (error)
|
|
return error;
|
|
|
|
/*
|
|
* An append-only file must be opened in append mode for writing.
|
|
*/
|
|
if (IS_APPEND(inode)) {
|
|
if ((flag & FMODE_WRITE) && !(flag & O_APPEND))
|
|
return -EPERM;
|
|
if (flag & O_TRUNC)
|
|
return -EPERM;
|
|
}
|
|
|
|
/* O_NOATIME can only be set by the owner or superuser */
|
|
if (flag & O_NOATIME && !is_owner_or_cap(inode))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* Ensure there are no outstanding leases on the file.
|
|
*/
|
|
return break_lease(inode, flag);
|
|
}
|
|
|
|
static int handle_truncate(struct path *path)
|
|
{
|
|
struct inode *inode = path->dentry->d_inode;
|
|
int error = get_write_access(inode);
|
|
if (error)
|
|
return error;
|
|
/*
|
|
* Refuse to truncate files with mandatory locks held on them.
|
|
*/
|
|
error = locks_verify_locked(inode);
|
|
if (!error)
|
|
error = security_path_truncate(path, 0,
|
|
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
|
|
if (!error) {
|
|
error = do_truncate(path->dentry, 0,
|
|
ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
|
|
NULL);
|
|
}
|
|
put_write_access(inode);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Be careful about ever adding any more callers of this
|
|
* function. Its flags must be in the namei format, not
|
|
* what get passed to sys_open().
|
|
*/
|
|
static int __open_namei_create(struct nameidata *nd, struct path *path,
|
|
int flag, int mode)
|
|
{
|
|
int error;
|
|
struct dentry *dir = nd->path.dentry;
|
|
|
|
if (!IS_POSIXACL(dir->d_inode))
|
|
mode &= ~current_umask();
|
|
error = security_path_mknod(&nd->path, path->dentry, mode, 0);
|
|
if (error)
|
|
goto out_unlock;
|
|
error = vfs_create(dir->d_inode, path->dentry, mode, nd);
|
|
out_unlock:
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
dput(nd->path.dentry);
|
|
nd->path.dentry = path->dentry;
|
|
if (error)
|
|
return error;
|
|
/* Don't check for write permission, don't truncate */
|
|
return may_open(&nd->path, 0, flag & ~O_TRUNC);
|
|
}
|
|
|
|
/*
|
|
* Note that while the flag value (low two bits) for sys_open means:
|
|
* 00 - read-only
|
|
* 01 - write-only
|
|
* 10 - read-write
|
|
* 11 - special
|
|
* it is changed into
|
|
* 00 - no permissions needed
|
|
* 01 - read-permission
|
|
* 10 - write-permission
|
|
* 11 - read-write
|
|
* for the internal routines (ie open_namei()/follow_link() etc)
|
|
* This is more logical, and also allows the 00 "no perm needed"
|
|
* to be used for symlinks (where the permissions are checked
|
|
* later).
|
|
*
|
|
*/
|
|
static inline int open_to_namei_flags(int flag)
|
|
{
|
|
if ((flag+1) & O_ACCMODE)
|
|
flag++;
|
|
return flag;
|
|
}
|
|
|
|
static int open_will_truncate(int flag, struct inode *inode)
|
|
{
|
|
/*
|
|
* We'll never write to the fs underlying
|
|
* a device file.
|
|
*/
|
|
if (special_file(inode->i_mode))
|
|
return 0;
|
|
return (flag & O_TRUNC);
|
|
}
|
|
|
|
/*
|
|
* Note that the low bits of the passed in "open_flag"
|
|
* are not the same as in the local variable "flag". See
|
|
* open_to_namei_flags() for more details.
|
|
*/
|
|
struct file *do_filp_open(int dfd, const char *pathname,
|
|
int open_flag, int mode, int acc_mode)
|
|
{
|
|
struct file *filp;
|
|
struct nameidata nd;
|
|
int error;
|
|
struct path path, save;
|
|
struct dentry *dir;
|
|
int count = 0;
|
|
int will_truncate;
|
|
int flag = open_to_namei_flags(open_flag);
|
|
|
|
/*
|
|
* O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
|
|
* check for O_DSYNC if the need any syncing at all we enforce it's
|
|
* always set instead of having to deal with possibly weird behaviour
|
|
* for malicious applications setting only __O_SYNC.
|
|
*/
|
|
if (open_flag & __O_SYNC)
|
|
open_flag |= O_DSYNC;
|
|
|
|
if (!acc_mode)
|
|
acc_mode = MAY_OPEN | ACC_MODE(flag);
|
|
|
|
/* O_TRUNC implies we need access checks for write permissions */
|
|
if (flag & O_TRUNC)
|
|
acc_mode |= MAY_WRITE;
|
|
|
|
/* Allow the LSM permission hook to distinguish append
|
|
access from general write access. */
|
|
if (flag & O_APPEND)
|
|
acc_mode |= MAY_APPEND;
|
|
|
|
/*
|
|
* The simplest case - just a plain lookup.
|
|
*/
|
|
if (!(flag & O_CREAT)) {
|
|
filp = get_empty_filp();
|
|
|
|
if (filp == NULL)
|
|
return ERR_PTR(-ENFILE);
|
|
nd.intent.open.file = filp;
|
|
filp->f_flags = open_flag;
|
|
nd.intent.open.flags = flag;
|
|
nd.intent.open.create_mode = 0;
|
|
error = do_path_lookup(dfd, pathname,
|
|
lookup_flags(flag)|LOOKUP_OPEN, &nd);
|
|
if (IS_ERR(nd.intent.open.file)) {
|
|
if (error == 0) {
|
|
error = PTR_ERR(nd.intent.open.file);
|
|
path_put(&nd.path);
|
|
}
|
|
} else if (error)
|
|
release_open_intent(&nd);
|
|
if (error)
|
|
return ERR_PTR(error);
|
|
goto ok;
|
|
}
|
|
|
|
/*
|
|
* Create - we need to know the parent.
|
|
*/
|
|
error = path_init(dfd, pathname, LOOKUP_PARENT, &nd);
|
|
if (error)
|
|
return ERR_PTR(error);
|
|
error = path_walk(pathname, &nd);
|
|
if (error) {
|
|
if (nd.root.mnt)
|
|
path_put(&nd.root);
|
|
return ERR_PTR(error);
|
|
}
|
|
if (unlikely(!audit_dummy_context()))
|
|
audit_inode(pathname, nd.path.dentry);
|
|
|
|
/*
|
|
* We have the parent and last component. First of all, check
|
|
* that we are not asked to creat(2) an obvious directory - that
|
|
* will not do.
|
|
*/
|
|
error = -EISDIR;
|
|
if (nd.last_type != LAST_NORM || nd.last.name[nd.last.len])
|
|
goto exit_parent;
|
|
|
|
error = -ENFILE;
|
|
filp = get_empty_filp();
|
|
if (filp == NULL)
|
|
goto exit_parent;
|
|
nd.intent.open.file = filp;
|
|
filp->f_flags = open_flag;
|
|
nd.intent.open.flags = flag;
|
|
nd.intent.open.create_mode = mode;
|
|
dir = nd.path.dentry;
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
nd.flags |= LOOKUP_CREATE | LOOKUP_OPEN;
|
|
if (flag & O_EXCL)
|
|
nd.flags |= LOOKUP_EXCL;
|
|
mutex_lock(&dir->d_inode->i_mutex);
|
|
path.dentry = lookup_hash(&nd);
|
|
path.mnt = nd.path.mnt;
|
|
|
|
do_last:
|
|
error = PTR_ERR(path.dentry);
|
|
if (IS_ERR(path.dentry)) {
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
goto exit;
|
|
}
|
|
|
|
if (IS_ERR(nd.intent.open.file)) {
|
|
error = PTR_ERR(nd.intent.open.file);
|
|
goto exit_mutex_unlock;
|
|
}
|
|
|
|
/* Negative dentry, just create the file */
|
|
if (!path.dentry->d_inode) {
|
|
/*
|
|
* This write is needed to ensure that a
|
|
* ro->rw transition does not occur between
|
|
* the time when the file is created and when
|
|
* a permanent write count is taken through
|
|
* the 'struct file' in nameidata_to_filp().
|
|
*/
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto exit_mutex_unlock;
|
|
error = __open_namei_create(&nd, &path, flag, mode);
|
|
if (error) {
|
|
mnt_drop_write(nd.path.mnt);
|
|
goto exit;
|
|
}
|
|
filp = nameidata_to_filp(&nd);
|
|
mnt_drop_write(nd.path.mnt);
|
|
if (nd.root.mnt)
|
|
path_put(&nd.root);
|
|
if (!IS_ERR(filp)) {
|
|
error = ima_path_check(&filp->f_path, filp->f_mode &
|
|
(MAY_READ | MAY_WRITE | MAY_EXEC));
|
|
if (error) {
|
|
fput(filp);
|
|
filp = ERR_PTR(error);
|
|
}
|
|
}
|
|
return filp;
|
|
}
|
|
|
|
/*
|
|
* It already exists.
|
|
*/
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
audit_inode(pathname, path.dentry);
|
|
|
|
error = -EEXIST;
|
|
if (flag & O_EXCL)
|
|
goto exit_dput;
|
|
|
|
if (__follow_mount(&path)) {
|
|
error = -ELOOP;
|
|
if (flag & O_NOFOLLOW)
|
|
goto exit_dput;
|
|
}
|
|
|
|
error = -ENOENT;
|
|
if (!path.dentry->d_inode)
|
|
goto exit_dput;
|
|
if (path.dentry->d_inode->i_op->follow_link)
|
|
goto do_link;
|
|
|
|
path_to_nameidata(&path, &nd);
|
|
error = -EISDIR;
|
|
if (S_ISDIR(path.dentry->d_inode->i_mode))
|
|
goto exit;
|
|
ok:
|
|
/*
|
|
* Consider:
|
|
* 1. may_open() truncates a file
|
|
* 2. a rw->ro mount transition occurs
|
|
* 3. nameidata_to_filp() fails due to
|
|
* the ro mount.
|
|
* That would be inconsistent, and should
|
|
* be avoided. Taking this mnt write here
|
|
* ensures that (2) can not occur.
|
|
*/
|
|
will_truncate = open_will_truncate(flag, nd.path.dentry->d_inode);
|
|
if (will_truncate) {
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto exit;
|
|
}
|
|
error = may_open(&nd.path, acc_mode, flag);
|
|
if (error) {
|
|
if (will_truncate)
|
|
mnt_drop_write(nd.path.mnt);
|
|
goto exit;
|
|
}
|
|
filp = nameidata_to_filp(&nd);
|
|
if (!IS_ERR(filp)) {
|
|
error = ima_path_check(&filp->f_path, filp->f_mode &
|
|
(MAY_READ | MAY_WRITE | MAY_EXEC));
|
|
if (error) {
|
|
fput(filp);
|
|
filp = ERR_PTR(error);
|
|
}
|
|
}
|
|
if (!IS_ERR(filp)) {
|
|
if (acc_mode & MAY_WRITE)
|
|
vfs_dq_init(nd.path.dentry->d_inode);
|
|
|
|
if (will_truncate) {
|
|
error = handle_truncate(&nd.path);
|
|
if (error) {
|
|
fput(filp);
|
|
filp = ERR_PTR(error);
|
|
}
|
|
}
|
|
}
|
|
/*
|
|
* It is now safe to drop the mnt write
|
|
* because the filp has had a write taken
|
|
* on its behalf.
|
|
*/
|
|
if (will_truncate)
|
|
mnt_drop_write(nd.path.mnt);
|
|
if (nd.root.mnt)
|
|
path_put(&nd.root);
|
|
return filp;
|
|
|
|
exit_mutex_unlock:
|
|
mutex_unlock(&dir->d_inode->i_mutex);
|
|
exit_dput:
|
|
path_put_conditional(&path, &nd);
|
|
exit:
|
|
if (!IS_ERR(nd.intent.open.file))
|
|
release_open_intent(&nd);
|
|
exit_parent:
|
|
if (nd.root.mnt)
|
|
path_put(&nd.root);
|
|
path_put(&nd.path);
|
|
return ERR_PTR(error);
|
|
|
|
do_link:
|
|
error = -ELOOP;
|
|
if (flag & O_NOFOLLOW)
|
|
goto exit_dput;
|
|
/*
|
|
* This is subtle. Instead of calling do_follow_link() we do the
|
|
* thing by hands. The reason is that this way we have zero link_count
|
|
* and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
|
|
* After that we have the parent and last component, i.e.
|
|
* we are in the same situation as after the first path_walk().
|
|
* Well, almost - if the last component is normal we get its copy
|
|
* stored in nd->last.name and we will have to putname() it when we
|
|
* are done. Procfs-like symlinks just set LAST_BIND.
|
|
*/
|
|
nd.flags |= LOOKUP_PARENT;
|
|
error = security_inode_follow_link(path.dentry, &nd);
|
|
if (error)
|
|
goto exit_dput;
|
|
save = nd.path;
|
|
path_get(&save);
|
|
error = __do_follow_link(&path, &nd);
|
|
if (error == -ESTALE) {
|
|
/* nd.path had been dropped */
|
|
nd.path = save;
|
|
path_get(&nd.path);
|
|
nd.flags |= LOOKUP_REVAL;
|
|
error = __do_follow_link(&path, &nd);
|
|
}
|
|
path_put(&save);
|
|
path_put(&path);
|
|
if (error) {
|
|
/* Does someone understand code flow here? Or it is only
|
|
* me so stupid? Anathema to whoever designed this non-sense
|
|
* with "intent.open".
|
|
*/
|
|
release_open_intent(&nd);
|
|
if (nd.root.mnt)
|
|
path_put(&nd.root);
|
|
return ERR_PTR(error);
|
|
}
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
if (nd.last_type == LAST_BIND)
|
|
goto ok;
|
|
error = -EISDIR;
|
|
if (nd.last_type != LAST_NORM)
|
|
goto exit;
|
|
if (nd.last.name[nd.last.len]) {
|
|
__putname(nd.last.name);
|
|
goto exit;
|
|
}
|
|
error = -ELOOP;
|
|
if (count++==32) {
|
|
__putname(nd.last.name);
|
|
goto exit;
|
|
}
|
|
dir = nd.path.dentry;
|
|
mutex_lock(&dir->d_inode->i_mutex);
|
|
path.dentry = lookup_hash(&nd);
|
|
path.mnt = nd.path.mnt;
|
|
__putname(nd.last.name);
|
|
goto do_last;
|
|
}
|
|
|
|
/**
|
|
* filp_open - open file and return file pointer
|
|
*
|
|
* @filename: path to open
|
|
* @flags: open flags as per the open(2) second argument
|
|
* @mode: mode for the new file if O_CREAT is set, else ignored
|
|
*
|
|
* This is the helper to open a file from kernelspace if you really
|
|
* have to. But in generally you should not do this, so please move
|
|
* along, nothing to see here..
|
|
*/
|
|
struct file *filp_open(const char *filename, int flags, int mode)
|
|
{
|
|
return do_filp_open(AT_FDCWD, filename, flags, mode, 0);
|
|
}
|
|
EXPORT_SYMBOL(filp_open);
|
|
|
|
/**
|
|
* lookup_create - lookup a dentry, creating it if it doesn't exist
|
|
* @nd: nameidata info
|
|
* @is_dir: directory flag
|
|
*
|
|
* Simple function to lookup and return a dentry and create it
|
|
* if it doesn't exist. Is SMP-safe.
|
|
*
|
|
* Returns with nd->path.dentry->d_inode->i_mutex locked.
|
|
*/
|
|
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
|
|
{
|
|
struct dentry *dentry = ERR_PTR(-EEXIST);
|
|
|
|
mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
/*
|
|
* Yucky last component or no last component at all?
|
|
* (foo/., foo/.., /////)
|
|
*/
|
|
if (nd->last_type != LAST_NORM)
|
|
goto fail;
|
|
nd->flags &= ~LOOKUP_PARENT;
|
|
nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL;
|
|
nd->intent.open.flags = O_EXCL;
|
|
|
|
/*
|
|
* Do the final lookup.
|
|
*/
|
|
dentry = lookup_hash(nd);
|
|
if (IS_ERR(dentry))
|
|
goto fail;
|
|
|
|
if (dentry->d_inode)
|
|
goto eexist;
|
|
/*
|
|
* Special case - lookup gave negative, but... we had foo/bar/
|
|
* From the vfs_mknod() POV we just have a negative dentry -
|
|
* all is fine. Let's be bastards - you had / on the end, you've
|
|
* been asking for (non-existent) directory. -ENOENT for you.
|
|
*/
|
|
if (unlikely(!is_dir && nd->last.name[nd->last.len])) {
|
|
dput(dentry);
|
|
dentry = ERR_PTR(-ENOENT);
|
|
}
|
|
return dentry;
|
|
eexist:
|
|
dput(dentry);
|
|
dentry = ERR_PTR(-EEXIST);
|
|
fail:
|
|
return dentry;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lookup_create);
|
|
|
|
int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
|
|
return -EPERM;
|
|
|
|
if (!dir->i_op->mknod)
|
|
return -EPERM;
|
|
|
|
error = devcgroup_inode_mknod(mode, dev);
|
|
if (error)
|
|
return error;
|
|
|
|
error = security_inode_mknod(dir, dentry, mode, dev);
|
|
if (error)
|
|
return error;
|
|
|
|
vfs_dq_init(dir);
|
|
error = dir->i_op->mknod(dir, dentry, mode, dev);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
static int may_mknod(mode_t mode)
|
|
{
|
|
switch (mode & S_IFMT) {
|
|
case S_IFREG:
|
|
case S_IFCHR:
|
|
case S_IFBLK:
|
|
case S_IFIFO:
|
|
case S_IFSOCK:
|
|
case 0: /* zero mode translates to S_IFREG */
|
|
return 0;
|
|
case S_IFDIR:
|
|
return -EPERM;
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode,
|
|
unsigned, dev)
|
|
{
|
|
int error;
|
|
char *tmp;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
|
|
if (S_ISDIR(mode))
|
|
return -EPERM;
|
|
|
|
error = user_path_parent(dfd, filename, &nd, &tmp);
|
|
if (error)
|
|
return error;
|
|
|
|
dentry = lookup_create(&nd, 0);
|
|
if (IS_ERR(dentry)) {
|
|
error = PTR_ERR(dentry);
|
|
goto out_unlock;
|
|
}
|
|
if (!IS_POSIXACL(nd.path.dentry->d_inode))
|
|
mode &= ~current_umask();
|
|
error = may_mknod(mode);
|
|
if (error)
|
|
goto out_dput;
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto out_dput;
|
|
error = security_path_mknod(&nd.path, dentry, mode, dev);
|
|
if (error)
|
|
goto out_drop_write;
|
|
switch (mode & S_IFMT) {
|
|
case 0: case S_IFREG:
|
|
error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd);
|
|
break;
|
|
case S_IFCHR: case S_IFBLK:
|
|
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,
|
|
new_decode_dev(dev));
|
|
break;
|
|
case S_IFIFO: case S_IFSOCK:
|
|
error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0);
|
|
break;
|
|
}
|
|
out_drop_write:
|
|
mnt_drop_write(nd.path.mnt);
|
|
out_dput:
|
|
dput(dentry);
|
|
out_unlock:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
path_put(&nd.path);
|
|
putname(tmp);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev)
|
|
{
|
|
return sys_mknodat(AT_FDCWD, filename, mode, dev);
|
|
}
|
|
|
|
int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->mkdir)
|
|
return -EPERM;
|
|
|
|
mode &= (S_IRWXUGO|S_ISVTX);
|
|
error = security_inode_mkdir(dir, dentry, mode);
|
|
if (error)
|
|
return error;
|
|
|
|
vfs_dq_init(dir);
|
|
error = dir->i_op->mkdir(dir, dentry, mode);
|
|
if (!error)
|
|
fsnotify_mkdir(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode)
|
|
{
|
|
int error = 0;
|
|
char * tmp;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
|
|
error = user_path_parent(dfd, pathname, &nd, &tmp);
|
|
if (error)
|
|
goto out_err;
|
|
|
|
dentry = lookup_create(&nd, 1);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out_unlock;
|
|
|
|
if (!IS_POSIXACL(nd.path.dentry->d_inode))
|
|
mode &= ~current_umask();
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto out_dput;
|
|
error = security_path_mkdir(&nd.path, dentry, mode);
|
|
if (error)
|
|
goto out_drop_write;
|
|
error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
|
|
out_drop_write:
|
|
mnt_drop_write(nd.path.mnt);
|
|
out_dput:
|
|
dput(dentry);
|
|
out_unlock:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
path_put(&nd.path);
|
|
putname(tmp);
|
|
out_err:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode)
|
|
{
|
|
return sys_mkdirat(AT_FDCWD, pathname, mode);
|
|
}
|
|
|
|
/*
|
|
* We try to drop the dentry early: we should have
|
|
* a usage count of 2 if we're the only user of this
|
|
* dentry, and if that is true (possibly after pruning
|
|
* the dcache), then we drop the dentry now.
|
|
*
|
|
* A low-level filesystem can, if it choses, legally
|
|
* do a
|
|
*
|
|
* if (!d_unhashed(dentry))
|
|
* return -EBUSY;
|
|
*
|
|
* if it cannot handle the case of removing a directory
|
|
* that is still in use by something else..
|
|
*/
|
|
void dentry_unhash(struct dentry *dentry)
|
|
{
|
|
dget(dentry);
|
|
shrink_dcache_parent(dentry);
|
|
spin_lock(&dcache_lock);
|
|
spin_lock(&dentry->d_lock);
|
|
if (atomic_read(&dentry->d_count) == 2)
|
|
__d_drop(dentry);
|
|
spin_unlock(&dentry->d_lock);
|
|
spin_unlock(&dcache_lock);
|
|
}
|
|
|
|
int vfs_rmdir(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
int error = may_delete(dir, dentry, 1);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->rmdir)
|
|
return -EPERM;
|
|
|
|
vfs_dq_init(dir);
|
|
|
|
mutex_lock(&dentry->d_inode->i_mutex);
|
|
dentry_unhash(dentry);
|
|
if (d_mountpoint(dentry))
|
|
error = -EBUSY;
|
|
else {
|
|
error = security_inode_rmdir(dir, dentry);
|
|
if (!error) {
|
|
error = dir->i_op->rmdir(dir, dentry);
|
|
if (!error)
|
|
dentry->d_inode->i_flags |= S_DEAD;
|
|
}
|
|
}
|
|
mutex_unlock(&dentry->d_inode->i_mutex);
|
|
if (!error) {
|
|
d_delete(dentry);
|
|
}
|
|
dput(dentry);
|
|
|
|
return error;
|
|
}
|
|
|
|
static long do_rmdir(int dfd, const char __user *pathname)
|
|
{
|
|
int error = 0;
|
|
char * name;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
|
|
error = user_path_parent(dfd, pathname, &nd, &name);
|
|
if (error)
|
|
return error;
|
|
|
|
switch(nd.last_type) {
|
|
case LAST_DOTDOT:
|
|
error = -ENOTEMPTY;
|
|
goto exit1;
|
|
case LAST_DOT:
|
|
error = -EINVAL;
|
|
goto exit1;
|
|
case LAST_ROOT:
|
|
error = -EBUSY;
|
|
goto exit1;
|
|
}
|
|
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
|
|
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
dentry = lookup_hash(&nd);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto exit2;
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto exit3;
|
|
error = security_path_rmdir(&nd.path, dentry);
|
|
if (error)
|
|
goto exit4;
|
|
error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
|
|
exit4:
|
|
mnt_drop_write(nd.path.mnt);
|
|
exit3:
|
|
dput(dentry);
|
|
exit2:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
exit1:
|
|
path_put(&nd.path);
|
|
putname(name);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
|
|
{
|
|
return do_rmdir(AT_FDCWD, pathname);
|
|
}
|
|
|
|
int vfs_unlink(struct inode *dir, struct dentry *dentry)
|
|
{
|
|
int error = may_delete(dir, dentry, 0);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->unlink)
|
|
return -EPERM;
|
|
|
|
vfs_dq_init(dir);
|
|
|
|
mutex_lock(&dentry->d_inode->i_mutex);
|
|
if (d_mountpoint(dentry))
|
|
error = -EBUSY;
|
|
else {
|
|
error = security_inode_unlink(dir, dentry);
|
|
if (!error)
|
|
error = dir->i_op->unlink(dir, dentry);
|
|
}
|
|
mutex_unlock(&dentry->d_inode->i_mutex);
|
|
|
|
/* We don't d_delete() NFS sillyrenamed files--they still exist. */
|
|
if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
|
|
fsnotify_link_count(dentry->d_inode);
|
|
d_delete(dentry);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Make sure that the actual truncation of the file will occur outside its
|
|
* directory's i_mutex. Truncate can take a long time if there is a lot of
|
|
* writeout happening, and we don't want to prevent access to the directory
|
|
* while waiting on the I/O.
|
|
*/
|
|
static long do_unlinkat(int dfd, const char __user *pathname)
|
|
{
|
|
int error;
|
|
char *name;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
struct inode *inode = NULL;
|
|
|
|
error = user_path_parent(dfd, pathname, &nd, &name);
|
|
if (error)
|
|
return error;
|
|
|
|
error = -EISDIR;
|
|
if (nd.last_type != LAST_NORM)
|
|
goto exit1;
|
|
|
|
nd.flags &= ~LOOKUP_PARENT;
|
|
|
|
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
|
|
dentry = lookup_hash(&nd);
|
|
error = PTR_ERR(dentry);
|
|
if (!IS_ERR(dentry)) {
|
|
/* Why not before? Because we want correct error value */
|
|
if (nd.last.name[nd.last.len])
|
|
goto slashes;
|
|
inode = dentry->d_inode;
|
|
if (inode)
|
|
atomic_inc(&inode->i_count);
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto exit2;
|
|
error = security_path_unlink(&nd.path, dentry);
|
|
if (error)
|
|
goto exit3;
|
|
error = vfs_unlink(nd.path.dentry->d_inode, dentry);
|
|
exit3:
|
|
mnt_drop_write(nd.path.mnt);
|
|
exit2:
|
|
dput(dentry);
|
|
}
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
if (inode)
|
|
iput(inode); /* truncate the inode here */
|
|
exit1:
|
|
path_put(&nd.path);
|
|
putname(name);
|
|
return error;
|
|
|
|
slashes:
|
|
error = !dentry->d_inode ? -ENOENT :
|
|
S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
|
|
goto exit2;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
|
|
{
|
|
if ((flag & ~AT_REMOVEDIR) != 0)
|
|
return -EINVAL;
|
|
|
|
if (flag & AT_REMOVEDIR)
|
|
return do_rmdir(dfd, pathname);
|
|
|
|
return do_unlinkat(dfd, pathname);
|
|
}
|
|
|
|
SYSCALL_DEFINE1(unlink, const char __user *, pathname)
|
|
{
|
|
return do_unlinkat(AT_FDCWD, pathname);
|
|
}
|
|
|
|
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
|
|
{
|
|
int error = may_create(dir, dentry);
|
|
|
|
if (error)
|
|
return error;
|
|
|
|
if (!dir->i_op->symlink)
|
|
return -EPERM;
|
|
|
|
error = security_inode_symlink(dir, dentry, oldname);
|
|
if (error)
|
|
return error;
|
|
|
|
vfs_dq_init(dir);
|
|
error = dir->i_op->symlink(dir, dentry, oldname);
|
|
if (!error)
|
|
fsnotify_create(dir, dentry);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname)
|
|
{
|
|
int error;
|
|
char *from;
|
|
char *to;
|
|
struct dentry *dentry;
|
|
struct nameidata nd;
|
|
|
|
from = getname(oldname);
|
|
if (IS_ERR(from))
|
|
return PTR_ERR(from);
|
|
|
|
error = user_path_parent(newdfd, newname, &nd, &to);
|
|
if (error)
|
|
goto out_putname;
|
|
|
|
dentry = lookup_create(&nd, 0);
|
|
error = PTR_ERR(dentry);
|
|
if (IS_ERR(dentry))
|
|
goto out_unlock;
|
|
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto out_dput;
|
|
error = security_path_symlink(&nd.path, dentry, from);
|
|
if (error)
|
|
goto out_drop_write;
|
|
error = vfs_symlink(nd.path.dentry->d_inode, dentry, from);
|
|
out_drop_write:
|
|
mnt_drop_write(nd.path.mnt);
|
|
out_dput:
|
|
dput(dentry);
|
|
out_unlock:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
path_put(&nd.path);
|
|
putname(to);
|
|
out_putname:
|
|
putname(from);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return sys_symlinkat(oldname, AT_FDCWD, newname);
|
|
}
|
|
|
|
int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
|
|
{
|
|
struct inode *inode = old_dentry->d_inode;
|
|
int error;
|
|
|
|
if (!inode)
|
|
return -ENOENT;
|
|
|
|
error = may_create(dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
if (dir->i_sb != inode->i_sb)
|
|
return -EXDEV;
|
|
|
|
/*
|
|
* A link to an append-only or immutable file cannot be created.
|
|
*/
|
|
if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
|
|
return -EPERM;
|
|
if (!dir->i_op->link)
|
|
return -EPERM;
|
|
if (S_ISDIR(inode->i_mode))
|
|
return -EPERM;
|
|
|
|
error = security_inode_link(old_dentry, dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
vfs_dq_init(dir);
|
|
error = dir->i_op->link(old_dentry, dir, new_dentry);
|
|
mutex_unlock(&inode->i_mutex);
|
|
if (!error)
|
|
fsnotify_link(dir, inode, new_dentry);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Hardlinks are often used in delicate situations. We avoid
|
|
* security-related surprises by not following symlinks on the
|
|
* newname. --KAB
|
|
*
|
|
* We don't follow them on the oldname either to be compatible
|
|
* with linux 2.0, and to avoid hard-linking to directories
|
|
* and other special files. --ADM
|
|
*/
|
|
SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname, int, flags)
|
|
{
|
|
struct dentry *new_dentry;
|
|
struct nameidata nd;
|
|
struct path old_path;
|
|
int error;
|
|
char *to;
|
|
|
|
if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
|
|
return -EINVAL;
|
|
|
|
error = user_path_at(olddfd, oldname,
|
|
flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
|
|
&old_path);
|
|
if (error)
|
|
return error;
|
|
|
|
error = user_path_parent(newdfd, newname, &nd, &to);
|
|
if (error)
|
|
goto out;
|
|
error = -EXDEV;
|
|
if (old_path.mnt != nd.path.mnt)
|
|
goto out_release;
|
|
new_dentry = lookup_create(&nd, 0);
|
|
error = PTR_ERR(new_dentry);
|
|
if (IS_ERR(new_dentry))
|
|
goto out_unlock;
|
|
error = mnt_want_write(nd.path.mnt);
|
|
if (error)
|
|
goto out_dput;
|
|
error = security_path_link(old_path.dentry, &nd.path, new_dentry);
|
|
if (error)
|
|
goto out_drop_write;
|
|
error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry);
|
|
out_drop_write:
|
|
mnt_drop_write(nd.path.mnt);
|
|
out_dput:
|
|
dput(new_dentry);
|
|
out_unlock:
|
|
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
|
|
out_release:
|
|
path_put(&nd.path);
|
|
putname(to);
|
|
out:
|
|
path_put(&old_path);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
|
|
}
|
|
|
|
/*
|
|
* The worst of all namespace operations - renaming directory. "Perverted"
|
|
* doesn't even start to describe it. Somebody in UCB had a heck of a trip...
|
|
* Problems:
|
|
* a) we can get into loop creation. Check is done in is_subdir().
|
|
* b) race potential - two innocent renames can create a loop together.
|
|
* That's where 4.4 screws up. Current fix: serialization on
|
|
* sb->s_vfs_rename_mutex. We might be more accurate, but that's another
|
|
* story.
|
|
* c) we have to lock _three_ objects - parents and victim (if it exists).
|
|
* And that - after we got ->i_mutex on parents (until then we don't know
|
|
* whether the target exists). Solution: try to be smart with locking
|
|
* order for inodes. We rely on the fact that tree topology may change
|
|
* only under ->s_vfs_rename_mutex _and_ that parent of the object we
|
|
* move will be locked. Thus we can rank directories by the tree
|
|
* (ancestors first) and rank all non-directories after them.
|
|
* That works since everybody except rename does "lock parent, lookup,
|
|
* lock child" and rename is under ->s_vfs_rename_mutex.
|
|
* HOWEVER, it relies on the assumption that any object with ->lookup()
|
|
* has no more than 1 dentry. If "hybrid" objects will ever appear,
|
|
* we'd better make sure that there's no link(2) for them.
|
|
* d) some filesystems don't support opened-but-unlinked directories,
|
|
* either because of layout or because they are not ready to deal with
|
|
* all cases correctly. The latter will be fixed (taking this sort of
|
|
* stuff into VFS), but the former is not going away. Solution: the same
|
|
* trick as in rmdir().
|
|
* e) conversion from fhandle to dentry may come in the wrong moment - when
|
|
* we are removing the target. Solution: we will have to grab ->i_mutex
|
|
* in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
|
|
* ->i_mutex on parents, which works but leads to some truely excessive
|
|
* locking].
|
|
*/
|
|
static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
int error = 0;
|
|
struct inode *target;
|
|
|
|
/*
|
|
* If we are going to change the parent - check write permissions,
|
|
* we'll need to flip '..'.
|
|
*/
|
|
if (new_dir != old_dir) {
|
|
error = inode_permission(old_dentry->d_inode, MAY_WRITE);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
target = new_dentry->d_inode;
|
|
if (target) {
|
|
mutex_lock(&target->i_mutex);
|
|
dentry_unhash(new_dentry);
|
|
}
|
|
if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
|
|
error = -EBUSY;
|
|
else
|
|
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (target) {
|
|
if (!error)
|
|
target->i_flags |= S_DEAD;
|
|
mutex_unlock(&target->i_mutex);
|
|
if (d_unhashed(new_dentry))
|
|
d_rehash(new_dentry);
|
|
dput(new_dentry);
|
|
}
|
|
if (!error)
|
|
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
|
|
d_move(old_dentry,new_dentry);
|
|
return error;
|
|
}
|
|
|
|
static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
struct inode *target;
|
|
int error;
|
|
|
|
error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (error)
|
|
return error;
|
|
|
|
dget(new_dentry);
|
|
target = new_dentry->d_inode;
|
|
if (target)
|
|
mutex_lock(&target->i_mutex);
|
|
if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
|
|
error = -EBUSY;
|
|
else
|
|
error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
|
|
if (!error) {
|
|
if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
|
|
d_move(old_dentry, new_dentry);
|
|
}
|
|
if (target)
|
|
mutex_unlock(&target->i_mutex);
|
|
dput(new_dentry);
|
|
return error;
|
|
}
|
|
|
|
int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
|
|
struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
int error;
|
|
int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
|
|
const char *old_name;
|
|
|
|
if (old_dentry->d_inode == new_dentry->d_inode)
|
|
return 0;
|
|
|
|
error = may_delete(old_dir, old_dentry, is_dir);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!new_dentry->d_inode)
|
|
error = may_create(new_dir, new_dentry);
|
|
else
|
|
error = may_delete(new_dir, new_dentry, is_dir);
|
|
if (error)
|
|
return error;
|
|
|
|
if (!old_dir->i_op->rename)
|
|
return -EPERM;
|
|
|
|
vfs_dq_init(old_dir);
|
|
vfs_dq_init(new_dir);
|
|
|
|
old_name = fsnotify_oldname_init(old_dentry->d_name.name);
|
|
|
|
if (is_dir)
|
|
error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
|
|
else
|
|
error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
|
|
if (!error) {
|
|
const char *new_name = old_dentry->d_name.name;
|
|
fsnotify_move(old_dir, new_dir, old_name, new_name, is_dir,
|
|
new_dentry->d_inode, old_dentry);
|
|
}
|
|
fsnotify_oldname_free(old_name);
|
|
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
|
|
int, newdfd, const char __user *, newname)
|
|
{
|
|
struct dentry *old_dir, *new_dir;
|
|
struct dentry *old_dentry, *new_dentry;
|
|
struct dentry *trap;
|
|
struct nameidata oldnd, newnd;
|
|
char *from;
|
|
char *to;
|
|
int error;
|
|
|
|
error = user_path_parent(olddfd, oldname, &oldnd, &from);
|
|
if (error)
|
|
goto exit;
|
|
|
|
error = user_path_parent(newdfd, newname, &newnd, &to);
|
|
if (error)
|
|
goto exit1;
|
|
|
|
error = -EXDEV;
|
|
if (oldnd.path.mnt != newnd.path.mnt)
|
|
goto exit2;
|
|
|
|
old_dir = oldnd.path.dentry;
|
|
error = -EBUSY;
|
|
if (oldnd.last_type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
new_dir = newnd.path.dentry;
|
|
if (newnd.last_type != LAST_NORM)
|
|
goto exit2;
|
|
|
|
oldnd.flags &= ~LOOKUP_PARENT;
|
|
newnd.flags &= ~LOOKUP_PARENT;
|
|
newnd.flags |= LOOKUP_RENAME_TARGET;
|
|
|
|
trap = lock_rename(new_dir, old_dir);
|
|
|
|
old_dentry = lookup_hash(&oldnd);
|
|
error = PTR_ERR(old_dentry);
|
|
if (IS_ERR(old_dentry))
|
|
goto exit3;
|
|
/* source must exist */
|
|
error = -ENOENT;
|
|
if (!old_dentry->d_inode)
|
|
goto exit4;
|
|
/* unless the source is a directory trailing slashes give -ENOTDIR */
|
|
if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
|
|
error = -ENOTDIR;
|
|
if (oldnd.last.name[oldnd.last.len])
|
|
goto exit4;
|
|
if (newnd.last.name[newnd.last.len])
|
|
goto exit4;
|
|
}
|
|
/* source should not be ancestor of target */
|
|
error = -EINVAL;
|
|
if (old_dentry == trap)
|
|
goto exit4;
|
|
new_dentry = lookup_hash(&newnd);
|
|
error = PTR_ERR(new_dentry);
|
|
if (IS_ERR(new_dentry))
|
|
goto exit4;
|
|
/* target should not be an ancestor of source */
|
|
error = -ENOTEMPTY;
|
|
if (new_dentry == trap)
|
|
goto exit5;
|
|
|
|
error = mnt_want_write(oldnd.path.mnt);
|
|
if (error)
|
|
goto exit5;
|
|
error = security_path_rename(&oldnd.path, old_dentry,
|
|
&newnd.path, new_dentry);
|
|
if (error)
|
|
goto exit6;
|
|
error = vfs_rename(old_dir->d_inode, old_dentry,
|
|
new_dir->d_inode, new_dentry);
|
|
exit6:
|
|
mnt_drop_write(oldnd.path.mnt);
|
|
exit5:
|
|
dput(new_dentry);
|
|
exit4:
|
|
dput(old_dentry);
|
|
exit3:
|
|
unlock_rename(new_dir, old_dir);
|
|
exit2:
|
|
path_put(&newnd.path);
|
|
putname(to);
|
|
exit1:
|
|
path_put(&oldnd.path);
|
|
putname(from);
|
|
exit:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
|
|
{
|
|
return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
|
|
}
|
|
|
|
int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
|
|
{
|
|
int len;
|
|
|
|
len = PTR_ERR(link);
|
|
if (IS_ERR(link))
|
|
goto out;
|
|
|
|
len = strlen(link);
|
|
if (len > (unsigned) buflen)
|
|
len = buflen;
|
|
if (copy_to_user(buffer, link, len))
|
|
len = -EFAULT;
|
|
out:
|
|
return len;
|
|
}
|
|
|
|
/*
|
|
* A helper for ->readlink(). This should be used *ONLY* for symlinks that
|
|
* have ->follow_link() touching nd only in nd_set_link(). Using (or not
|
|
* using) it for any given inode is up to filesystem.
|
|
*/
|
|
int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
|
|
{
|
|
struct nameidata nd;
|
|
void *cookie;
|
|
int res;
|
|
|
|
nd.depth = 0;
|
|
cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
|
|
if (IS_ERR(cookie))
|
|
return PTR_ERR(cookie);
|
|
|
|
res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
|
|
if (dentry->d_inode->i_op->put_link)
|
|
dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
|
|
return res;
|
|
}
|
|
|
|
int vfs_follow_link(struct nameidata *nd, const char *link)
|
|
{
|
|
return __vfs_follow_link(nd, link);
|
|
}
|
|
|
|
/* get the link contents into pagecache */
|
|
static char *page_getlink(struct dentry * dentry, struct page **ppage)
|
|
{
|
|
char *kaddr;
|
|
struct page *page;
|
|
struct address_space *mapping = dentry->d_inode->i_mapping;
|
|
page = read_mapping_page(mapping, 0, NULL);
|
|
if (IS_ERR(page))
|
|
return (char*)page;
|
|
*ppage = page;
|
|
kaddr = kmap(page);
|
|
nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
|
|
return kaddr;
|
|
}
|
|
|
|
int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
|
|
{
|
|
struct page *page = NULL;
|
|
char *s = page_getlink(dentry, &page);
|
|
int res = vfs_readlink(dentry,buffer,buflen,s);
|
|
if (page) {
|
|
kunmap(page);
|
|
page_cache_release(page);
|
|
}
|
|
return res;
|
|
}
|
|
|
|
void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
|
|
{
|
|
struct page *page = NULL;
|
|
nd_set_link(nd, page_getlink(dentry, &page));
|
|
return page;
|
|
}
|
|
|
|
void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
|
|
{
|
|
struct page *page = cookie;
|
|
|
|
if (page) {
|
|
kunmap(page);
|
|
page_cache_release(page);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
|
|
*/
|
|
int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
|
|
{
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct page *page;
|
|
void *fsdata;
|
|
int err;
|
|
char *kaddr;
|
|
unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
|
|
if (nofs)
|
|
flags |= AOP_FLAG_NOFS;
|
|
|
|
retry:
|
|
err = pagecache_write_begin(NULL, mapping, 0, len-1,
|
|
flags, &page, &fsdata);
|
|
if (err)
|
|
goto fail;
|
|
|
|
kaddr = kmap_atomic(page, KM_USER0);
|
|
memcpy(kaddr, symname, len-1);
|
|
kunmap_atomic(kaddr, KM_USER0);
|
|
|
|
err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
|
|
page, fsdata);
|
|
if (err < 0)
|
|
goto fail;
|
|
if (err < len-1)
|
|
goto retry;
|
|
|
|
mark_inode_dirty(inode);
|
|
return 0;
|
|
fail:
|
|
return err;
|
|
}
|
|
|
|
int page_symlink(struct inode *inode, const char *symname, int len)
|
|
{
|
|
return __page_symlink(inode, symname, len,
|
|
!(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
|
|
}
|
|
|
|
const struct inode_operations page_symlink_inode_operations = {
|
|
.readlink = generic_readlink,
|
|
.follow_link = page_follow_link_light,
|
|
.put_link = page_put_link,
|
|
};
|
|
|
|
EXPORT_SYMBOL(user_path_at);
|
|
EXPORT_SYMBOL(follow_down);
|
|
EXPORT_SYMBOL(follow_up);
|
|
EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
|
|
EXPORT_SYMBOL(getname);
|
|
EXPORT_SYMBOL(lock_rename);
|
|
EXPORT_SYMBOL(lookup_one_len);
|
|
EXPORT_SYMBOL(page_follow_link_light);
|
|
EXPORT_SYMBOL(page_put_link);
|
|
EXPORT_SYMBOL(page_readlink);
|
|
EXPORT_SYMBOL(__page_symlink);
|
|
EXPORT_SYMBOL(page_symlink);
|
|
EXPORT_SYMBOL(page_symlink_inode_operations);
|
|
EXPORT_SYMBOL(path_lookup);
|
|
EXPORT_SYMBOL(kern_path);
|
|
EXPORT_SYMBOL(vfs_path_lookup);
|
|
EXPORT_SYMBOL(inode_permission);
|
|
EXPORT_SYMBOL(file_permission);
|
|
EXPORT_SYMBOL(unlock_rename);
|
|
EXPORT_SYMBOL(vfs_create);
|
|
EXPORT_SYMBOL(vfs_follow_link);
|
|
EXPORT_SYMBOL(vfs_link);
|
|
EXPORT_SYMBOL(vfs_mkdir);
|
|
EXPORT_SYMBOL(vfs_mknod);
|
|
EXPORT_SYMBOL(generic_permission);
|
|
EXPORT_SYMBOL(vfs_readlink);
|
|
EXPORT_SYMBOL(vfs_rename);
|
|
EXPORT_SYMBOL(vfs_rmdir);
|
|
EXPORT_SYMBOL(vfs_symlink);
|
|
EXPORT_SYMBOL(vfs_unlink);
|
|
EXPORT_SYMBOL(dentry_unhash);
|
|
EXPORT_SYMBOL(generic_readlink);
|