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![david m. richter](/assets/img/avatar_default.png)
It is possible that another process could acquire a new file lease right after break_lease() is called during a truncate, but before lease-granting is disabled by the subsequent get_write_access(). Merely switching the order of the break_lease() and get_write_access() calls prevents this race. Signed-off-by: David M. Richter <richterd@citi.umich.edu> Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1192 lines
26 KiB
C
1192 lines
26 KiB
C
/*
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* linux/fs/open.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/file.h>
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#include <linux/quotaops.h>
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#include <linux/fsnotify.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/tty.h>
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#include <linux/namei.h>
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#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include <linux/security.h>
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#include <linux/mount.h>
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#include <linux/vfs.h>
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#include <linux/fcntl.h>
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#include <asm/uaccess.h>
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#include <linux/fs.h>
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#include <linux/personality.h>
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#include <linux/pagemap.h>
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#include <linux/syscalls.h>
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#include <linux/rcupdate.h>
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#include <linux/audit.h>
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#include <linux/falloc.h>
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int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
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{
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int retval = -ENODEV;
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if (dentry) {
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retval = -ENOSYS;
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if (dentry->d_sb->s_op->statfs) {
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memset(buf, 0, sizeof(*buf));
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retval = security_sb_statfs(dentry);
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if (retval)
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return retval;
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retval = dentry->d_sb->s_op->statfs(dentry, buf);
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if (retval == 0 && buf->f_frsize == 0)
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buf->f_frsize = buf->f_bsize;
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}
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}
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return retval;
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}
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EXPORT_SYMBOL(vfs_statfs);
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static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
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{
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struct kstatfs st;
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int retval;
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retval = vfs_statfs(dentry, &st);
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if (retval)
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return retval;
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if (sizeof(*buf) == sizeof(st))
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memcpy(buf, &st, sizeof(st));
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else {
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if (sizeof buf->f_blocks == 4) {
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if ((st.f_blocks | st.f_bfree | st.f_bavail) &
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0xffffffff00000000ULL)
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return -EOVERFLOW;
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/*
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* f_files and f_ffree may be -1; it's okay to stuff
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* that into 32 bits
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*/
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if (st.f_files != -1 &&
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(st.f_files & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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if (st.f_ffree != -1 &&
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(st.f_ffree & 0xffffffff00000000ULL))
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return -EOVERFLOW;
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}
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buf->f_type = st.f_type;
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buf->f_bsize = st.f_bsize;
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buf->f_blocks = st.f_blocks;
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buf->f_bfree = st.f_bfree;
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buf->f_bavail = st.f_bavail;
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buf->f_files = st.f_files;
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buf->f_ffree = st.f_ffree;
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buf->f_fsid = st.f_fsid;
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buf->f_namelen = st.f_namelen;
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buf->f_frsize = st.f_frsize;
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memset(buf->f_spare, 0, sizeof(buf->f_spare));
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}
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return 0;
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}
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static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
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{
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struct kstatfs st;
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int retval;
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retval = vfs_statfs(dentry, &st);
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if (retval)
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return retval;
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if (sizeof(*buf) == sizeof(st))
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memcpy(buf, &st, sizeof(st));
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else {
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buf->f_type = st.f_type;
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buf->f_bsize = st.f_bsize;
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buf->f_blocks = st.f_blocks;
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buf->f_bfree = st.f_bfree;
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buf->f_bavail = st.f_bavail;
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buf->f_files = st.f_files;
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buf->f_ffree = st.f_ffree;
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buf->f_fsid = st.f_fsid;
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buf->f_namelen = st.f_namelen;
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buf->f_frsize = st.f_frsize;
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memset(buf->f_spare, 0, sizeof(buf->f_spare));
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}
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return 0;
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}
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asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
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{
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struct nameidata nd;
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int error;
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error = user_path_walk(path, &nd);
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if (!error) {
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struct statfs tmp;
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error = vfs_statfs_native(nd.dentry, &tmp);
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if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
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error = -EFAULT;
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path_release(&nd);
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}
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return error;
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}
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asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
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{
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struct nameidata nd;
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long error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = user_path_walk(path, &nd);
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if (!error) {
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struct statfs64 tmp;
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error = vfs_statfs64(nd.dentry, &tmp);
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if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
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error = -EFAULT;
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path_release(&nd);
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}
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return error;
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}
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asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
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{
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struct file * file;
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struct statfs tmp;
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int error;
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error = -EBADF;
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file = fget(fd);
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if (!file)
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goto out;
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error = vfs_statfs_native(file->f_path.dentry, &tmp);
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if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
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error = -EFAULT;
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fput(file);
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out:
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return error;
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}
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asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
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{
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struct file * file;
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struct statfs64 tmp;
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int error;
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if (sz != sizeof(*buf))
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return -EINVAL;
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error = -EBADF;
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file = fget(fd);
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if (!file)
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goto out;
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error = vfs_statfs64(file->f_path.dentry, &tmp);
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if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
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error = -EFAULT;
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fput(file);
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out:
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return error;
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}
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int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
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struct file *filp)
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{
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int err;
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struct iattr newattrs;
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/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
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if (length < 0)
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return -EINVAL;
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newattrs.ia_size = length;
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newattrs.ia_valid = ATTR_SIZE | time_attrs;
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if (filp) {
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newattrs.ia_file = filp;
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newattrs.ia_valid |= ATTR_FILE;
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}
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/* Remove suid/sgid on truncate too */
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newattrs.ia_valid |= should_remove_suid(dentry);
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mutex_lock(&dentry->d_inode->i_mutex);
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err = notify_change(dentry, &newattrs);
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mutex_unlock(&dentry->d_inode->i_mutex);
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return err;
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}
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static long do_sys_truncate(const char __user * path, loff_t length)
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{
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struct nameidata nd;
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struct inode * inode;
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int error;
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error = -EINVAL;
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if (length < 0) /* sorry, but loff_t says... */
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goto out;
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error = user_path_walk(path, &nd);
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if (error)
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goto out;
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inode = nd.dentry->d_inode;
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/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
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error = -EISDIR;
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if (S_ISDIR(inode->i_mode))
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goto dput_and_out;
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error = -EINVAL;
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if (!S_ISREG(inode->i_mode))
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goto dput_and_out;
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error = vfs_permission(&nd, MAY_WRITE);
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if (error)
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goto dput_and_out;
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error = -EROFS;
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if (IS_RDONLY(inode))
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goto dput_and_out;
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error = -EPERM;
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if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
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goto dput_and_out;
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error = get_write_access(inode);
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if (error)
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goto dput_and_out;
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/*
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* Make sure that there are no leases. get_write_access() protects
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* against the truncate racing with a lease-granting setlease().
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*/
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error = break_lease(inode, FMODE_WRITE);
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if (error)
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goto put_write_and_out;
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error = locks_verify_truncate(inode, NULL, length);
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if (!error) {
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DQUOT_INIT(inode);
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error = do_truncate(nd.dentry, length, 0, NULL);
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}
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put_write_and_out:
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put_write_access(inode);
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dput_and_out:
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path_release(&nd);
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out:
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return error;
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}
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asmlinkage long sys_truncate(const char __user * path, unsigned long length)
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{
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/* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
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return do_sys_truncate(path, (long)length);
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}
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static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
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{
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struct inode * inode;
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struct dentry *dentry;
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struct file * file;
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int error;
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error = -EINVAL;
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if (length < 0)
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goto out;
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error = -EBADF;
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file = fget(fd);
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if (!file)
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goto out;
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/* explicitly opened as large or we are on 64-bit box */
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if (file->f_flags & O_LARGEFILE)
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small = 0;
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dentry = file->f_path.dentry;
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inode = dentry->d_inode;
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error = -EINVAL;
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if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
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goto out_putf;
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error = -EINVAL;
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/* Cannot ftruncate over 2^31 bytes without large file support */
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if (small && length > MAX_NON_LFS)
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goto out_putf;
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error = -EPERM;
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if (IS_APPEND(inode))
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goto out_putf;
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error = locks_verify_truncate(inode, file, length);
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if (!error)
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error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
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out_putf:
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fput(file);
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out:
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return error;
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}
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asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
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{
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long ret = do_sys_ftruncate(fd, length, 1);
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/* avoid REGPARM breakage on x86: */
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prevent_tail_call(ret);
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return ret;
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}
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/* LFS versions of truncate are only needed on 32 bit machines */
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#if BITS_PER_LONG == 32
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asmlinkage long sys_truncate64(const char __user * path, loff_t length)
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{
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return do_sys_truncate(path, length);
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}
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asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
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{
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long ret = do_sys_ftruncate(fd, length, 0);
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/* avoid REGPARM breakage on x86: */
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prevent_tail_call(ret);
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return ret;
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}
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#endif
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asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
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{
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struct file *file;
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struct inode *inode;
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long ret = -EINVAL;
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if (offset < 0 || len <= 0)
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goto out;
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/* Return error if mode is not supported */
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ret = -EOPNOTSUPP;
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if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
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goto out;
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ret = -EBADF;
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file = fget(fd);
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if (!file)
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goto out;
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if (!(file->f_mode & FMODE_WRITE))
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goto out_fput;
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/*
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* Revalidate the write permissions, in case security policy has
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* changed since the files were opened.
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*/
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ret = security_file_permission(file, MAY_WRITE);
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if (ret)
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goto out_fput;
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inode = file->f_path.dentry->d_inode;
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|
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ret = -ESPIPE;
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if (S_ISFIFO(inode->i_mode))
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goto out_fput;
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|
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ret = -ENODEV;
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/*
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* Let individual file system decide if it supports preallocation
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* for directories or not.
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*/
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if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
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goto out_fput;
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|
|
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ret = -EFBIG;
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/* Check for wrap through zero too */
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if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
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goto out_fput;
|
|
|
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if (inode->i_op && inode->i_op->fallocate)
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ret = inode->i_op->fallocate(inode, mode, offset, len);
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else
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ret = -EOPNOTSUPP;
|
|
|
|
out_fput:
|
|
fput(file);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
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* access() needs to use the real uid/gid, not the effective uid/gid.
|
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* We do this by temporarily clearing all FS-related capabilities and
|
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* switching the fsuid/fsgid around to the real ones.
|
|
*/
|
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asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
|
|
{
|
|
struct nameidata nd;
|
|
int old_fsuid, old_fsgid;
|
|
kernel_cap_t old_cap;
|
|
int res;
|
|
|
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if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
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return -EINVAL;
|
|
|
|
old_fsuid = current->fsuid;
|
|
old_fsgid = current->fsgid;
|
|
old_cap = current->cap_effective;
|
|
|
|
current->fsuid = current->uid;
|
|
current->fsgid = current->gid;
|
|
|
|
/*
|
|
* Clear the capabilities if we switch to a non-root user
|
|
*
|
|
* FIXME: There is a race here against sys_capset. The
|
|
* capabilities can change yet we will restore the old
|
|
* value below. We should hold task_capabilities_lock,
|
|
* but we cannot because user_path_walk can sleep.
|
|
*/
|
|
if (current->uid)
|
|
cap_clear(current->cap_effective);
|
|
else
|
|
current->cap_effective = current->cap_permitted;
|
|
|
|
res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
|
|
if (res)
|
|
goto out;
|
|
|
|
res = vfs_permission(&nd, mode);
|
|
/* SuS v2 requires we report a read only fs too */
|
|
if(res || !(mode & S_IWOTH) ||
|
|
special_file(nd.dentry->d_inode->i_mode))
|
|
goto out_path_release;
|
|
|
|
if(IS_RDONLY(nd.dentry->d_inode))
|
|
res = -EROFS;
|
|
|
|
out_path_release:
|
|
path_release(&nd);
|
|
out:
|
|
current->fsuid = old_fsuid;
|
|
current->fsgid = old_fsgid;
|
|
current->cap_effective = old_cap;
|
|
|
|
return res;
|
|
}
|
|
|
|
asmlinkage long sys_access(const char __user *filename, int mode)
|
|
{
|
|
return sys_faccessat(AT_FDCWD, filename, mode);
|
|
}
|
|
|
|
asmlinkage long sys_chdir(const char __user * filename)
|
|
{
|
|
struct nameidata nd;
|
|
int error;
|
|
|
|
error = __user_walk(filename,
|
|
LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = vfs_permission(&nd, MAY_EXEC);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
set_fs_pwd(current->fs, nd.mnt, nd.dentry);
|
|
|
|
dput_and_out:
|
|
path_release(&nd);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_fchdir(unsigned int fd)
|
|
{
|
|
struct file *file;
|
|
struct dentry *dentry;
|
|
struct inode *inode;
|
|
struct vfsmount *mnt;
|
|
int error;
|
|
|
|
error = -EBADF;
|
|
file = fget(fd);
|
|
if (!file)
|
|
goto out;
|
|
|
|
dentry = file->f_path.dentry;
|
|
mnt = file->f_path.mnt;
|
|
inode = dentry->d_inode;
|
|
|
|
error = -ENOTDIR;
|
|
if (!S_ISDIR(inode->i_mode))
|
|
goto out_putf;
|
|
|
|
error = file_permission(file, MAY_EXEC);
|
|
if (!error)
|
|
set_fs_pwd(current->fs, mnt, dentry);
|
|
out_putf:
|
|
fput(file);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_chroot(const char __user * filename)
|
|
{
|
|
struct nameidata nd;
|
|
int error;
|
|
|
|
error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = vfs_permission(&nd, MAY_EXEC);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
error = -EPERM;
|
|
if (!capable(CAP_SYS_CHROOT))
|
|
goto dput_and_out;
|
|
|
|
set_fs_root(current->fs, nd.mnt, nd.dentry);
|
|
set_fs_altroot();
|
|
error = 0;
|
|
dput_and_out:
|
|
path_release(&nd);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
|
|
{
|
|
struct inode * inode;
|
|
struct dentry * dentry;
|
|
struct file * file;
|
|
int err = -EBADF;
|
|
struct iattr newattrs;
|
|
|
|
file = fget(fd);
|
|
if (!file)
|
|
goto out;
|
|
|
|
dentry = file->f_path.dentry;
|
|
inode = dentry->d_inode;
|
|
|
|
audit_inode(NULL, inode);
|
|
|
|
err = -EROFS;
|
|
if (IS_RDONLY(inode))
|
|
goto out_putf;
|
|
err = -EPERM;
|
|
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
|
|
goto out_putf;
|
|
mutex_lock(&inode->i_mutex);
|
|
if (mode == (mode_t) -1)
|
|
mode = inode->i_mode;
|
|
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
|
|
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
|
|
err = notify_change(dentry, &newattrs);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
out_putf:
|
|
fput(file);
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
|
|
mode_t mode)
|
|
{
|
|
struct nameidata nd;
|
|
struct inode * inode;
|
|
int error;
|
|
struct iattr newattrs;
|
|
|
|
error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
|
|
if (error)
|
|
goto out;
|
|
inode = nd.dentry->d_inode;
|
|
|
|
error = -EROFS;
|
|
if (IS_RDONLY(inode))
|
|
goto dput_and_out;
|
|
|
|
error = -EPERM;
|
|
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
|
|
goto dput_and_out;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
if (mode == (mode_t) -1)
|
|
mode = inode->i_mode;
|
|
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
|
|
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
|
|
error = notify_change(nd.dentry, &newattrs);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
dput_and_out:
|
|
path_release(&nd);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_chmod(const char __user *filename, mode_t mode)
|
|
{
|
|
return sys_fchmodat(AT_FDCWD, filename, mode);
|
|
}
|
|
|
|
static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
|
|
{
|
|
struct inode * inode;
|
|
int error;
|
|
struct iattr newattrs;
|
|
|
|
error = -ENOENT;
|
|
if (!(inode = dentry->d_inode)) {
|
|
printk(KERN_ERR "chown_common: NULL inode\n");
|
|
goto out;
|
|
}
|
|
error = -EROFS;
|
|
if (IS_RDONLY(inode))
|
|
goto out;
|
|
error = -EPERM;
|
|
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
|
|
goto out;
|
|
newattrs.ia_valid = ATTR_CTIME;
|
|
if (user != (uid_t) -1) {
|
|
newattrs.ia_valid |= ATTR_UID;
|
|
newattrs.ia_uid = user;
|
|
}
|
|
if (group != (gid_t) -1) {
|
|
newattrs.ia_valid |= ATTR_GID;
|
|
newattrs.ia_gid = group;
|
|
}
|
|
if (!S_ISDIR(inode->i_mode))
|
|
newattrs.ia_valid |= ATTR_KILL_SUID|ATTR_KILL_SGID;
|
|
mutex_lock(&inode->i_mutex);
|
|
error = notify_change(dentry, &newattrs);
|
|
mutex_unlock(&inode->i_mutex);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
|
|
{
|
|
struct nameidata nd;
|
|
int error;
|
|
|
|
error = user_path_walk(filename, &nd);
|
|
if (error)
|
|
goto out;
|
|
error = chown_common(nd.dentry, user, group);
|
|
path_release(&nd);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
|
|
gid_t group, int flag)
|
|
{
|
|
struct nameidata nd;
|
|
int error = -EINVAL;
|
|
int follow;
|
|
|
|
if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
|
|
goto out;
|
|
|
|
follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
|
|
error = __user_walk_fd(dfd, filename, follow, &nd);
|
|
if (error)
|
|
goto out;
|
|
error = chown_common(nd.dentry, user, group);
|
|
path_release(&nd);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
|
|
{
|
|
struct nameidata nd;
|
|
int error;
|
|
|
|
error = user_path_walk_link(filename, &nd);
|
|
if (error)
|
|
goto out;
|
|
error = chown_common(nd.dentry, user, group);
|
|
path_release(&nd);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
|
|
asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
|
|
{
|
|
struct file * file;
|
|
int error = -EBADF;
|
|
struct dentry * dentry;
|
|
|
|
file = fget(fd);
|
|
if (!file)
|
|
goto out;
|
|
|
|
dentry = file->f_path.dentry;
|
|
audit_inode(NULL, dentry->d_inode);
|
|
error = chown_common(dentry, user, group);
|
|
fput(file);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
|
|
int flags, struct file *f,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
struct inode *inode;
|
|
int error;
|
|
|
|
f->f_flags = flags;
|
|
f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
|
|
FMODE_PREAD | FMODE_PWRITE;
|
|
inode = dentry->d_inode;
|
|
if (f->f_mode & FMODE_WRITE) {
|
|
error = get_write_access(inode);
|
|
if (error)
|
|
goto cleanup_file;
|
|
}
|
|
|
|
f->f_mapping = inode->i_mapping;
|
|
f->f_path.dentry = dentry;
|
|
f->f_path.mnt = mnt;
|
|
f->f_pos = 0;
|
|
f->f_op = fops_get(inode->i_fop);
|
|
file_move(f, &inode->i_sb->s_files);
|
|
|
|
if (!open && f->f_op)
|
|
open = f->f_op->open;
|
|
if (open) {
|
|
error = open(inode, f);
|
|
if (error)
|
|
goto cleanup_all;
|
|
}
|
|
|
|
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
|
|
|
|
file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
|
|
|
|
/* NB: we're sure to have correct a_ops only after f_op->open */
|
|
if (f->f_flags & O_DIRECT) {
|
|
if (!f->f_mapping->a_ops ||
|
|
((!f->f_mapping->a_ops->direct_IO) &&
|
|
(!f->f_mapping->a_ops->get_xip_page))) {
|
|
fput(f);
|
|
f = ERR_PTR(-EINVAL);
|
|
}
|
|
}
|
|
|
|
return f;
|
|
|
|
cleanup_all:
|
|
fops_put(f->f_op);
|
|
if (f->f_mode & FMODE_WRITE)
|
|
put_write_access(inode);
|
|
file_kill(f);
|
|
f->f_path.dentry = NULL;
|
|
f->f_path.mnt = NULL;
|
|
cleanup_file:
|
|
put_filp(f);
|
|
dput(dentry);
|
|
mntput(mnt);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
/*
|
|
* 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). 00 is
|
|
* used by symlinks.
|
|
*/
|
|
static struct file *do_filp_open(int dfd, const char *filename, int flags,
|
|
int mode)
|
|
{
|
|
int namei_flags, error;
|
|
struct nameidata nd;
|
|
|
|
namei_flags = flags;
|
|
if ((namei_flags+1) & O_ACCMODE)
|
|
namei_flags++;
|
|
|
|
error = open_namei(dfd, filename, namei_flags, mode, &nd);
|
|
if (!error)
|
|
return nameidata_to_filp(&nd, flags);
|
|
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
struct file *filp_open(const char *filename, int flags, int mode)
|
|
{
|
|
return do_filp_open(AT_FDCWD, filename, flags, mode);
|
|
}
|
|
EXPORT_SYMBOL(filp_open);
|
|
|
|
/**
|
|
* lookup_instantiate_filp - instantiates the open intent filp
|
|
* @nd: pointer to nameidata
|
|
* @dentry: pointer to dentry
|
|
* @open: open callback
|
|
*
|
|
* Helper for filesystems that want to use lookup open intents and pass back
|
|
* a fully instantiated struct file to the caller.
|
|
* This function is meant to be called from within a filesystem's
|
|
* lookup method.
|
|
* Beware of calling it for non-regular files! Those ->open methods might block
|
|
* (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
|
|
* leading to a deadlock, as nobody can open that fifo anymore, because
|
|
* another process to open fifo will block on locked parent when doing lookup).
|
|
* Note that in case of error, nd->intent.open.file is destroyed, but the
|
|
* path information remains valid.
|
|
* If the open callback is set to NULL, then the standard f_op->open()
|
|
* filesystem callback is substituted.
|
|
*/
|
|
struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
if (IS_ERR(nd->intent.open.file))
|
|
goto out;
|
|
if (IS_ERR(dentry))
|
|
goto out_err;
|
|
nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt),
|
|
nd->intent.open.flags - 1,
|
|
nd->intent.open.file,
|
|
open);
|
|
out:
|
|
return nd->intent.open.file;
|
|
out_err:
|
|
release_open_intent(nd);
|
|
nd->intent.open.file = (struct file *)dentry;
|
|
goto out;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
|
|
|
|
/**
|
|
* nameidata_to_filp - convert a nameidata to an open filp.
|
|
* @nd: pointer to nameidata
|
|
* @flags: open flags
|
|
*
|
|
* Note that this function destroys the original nameidata
|
|
*/
|
|
struct file *nameidata_to_filp(struct nameidata *nd, int flags)
|
|
{
|
|
struct file *filp;
|
|
|
|
/* Pick up the filp from the open intent */
|
|
filp = nd->intent.open.file;
|
|
/* Has the filesystem initialised the file for us? */
|
|
if (filp->f_path.dentry == NULL)
|
|
filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL);
|
|
else
|
|
path_release(nd);
|
|
return filp;
|
|
}
|
|
|
|
/*
|
|
* dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
|
|
* error.
|
|
*/
|
|
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
|
|
{
|
|
int error;
|
|
struct file *f;
|
|
|
|
error = -ENFILE;
|
|
f = get_empty_filp();
|
|
if (f == NULL) {
|
|
dput(dentry);
|
|
mntput(mnt);
|
|
return ERR_PTR(error);
|
|
}
|
|
|
|
return __dentry_open(dentry, mnt, flags, f, NULL);
|
|
}
|
|
EXPORT_SYMBOL(dentry_open);
|
|
|
|
/*
|
|
* Find an empty file descriptor entry, and mark it busy.
|
|
*/
|
|
int get_unused_fd_flags(int flags)
|
|
{
|
|
struct files_struct * files = current->files;
|
|
int fd, error;
|
|
struct fdtable *fdt;
|
|
|
|
error = -EMFILE;
|
|
spin_lock(&files->file_lock);
|
|
|
|
repeat:
|
|
fdt = files_fdtable(files);
|
|
fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,
|
|
files->next_fd);
|
|
|
|
/*
|
|
* N.B. For clone tasks sharing a files structure, this test
|
|
* will limit the total number of files that can be opened.
|
|
*/
|
|
if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
|
|
goto out;
|
|
|
|
/* Do we need to expand the fd array or fd set? */
|
|
error = expand_files(files, fd);
|
|
if (error < 0)
|
|
goto out;
|
|
|
|
if (error) {
|
|
/*
|
|
* If we needed to expand the fs array we
|
|
* might have blocked - try again.
|
|
*/
|
|
error = -EMFILE;
|
|
goto repeat;
|
|
}
|
|
|
|
FD_SET(fd, fdt->open_fds);
|
|
if (flags & O_CLOEXEC)
|
|
FD_SET(fd, fdt->close_on_exec);
|
|
else
|
|
FD_CLR(fd, fdt->close_on_exec);
|
|
files->next_fd = fd + 1;
|
|
#if 1
|
|
/* Sanity check */
|
|
if (fdt->fd[fd] != NULL) {
|
|
printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
|
|
fdt->fd[fd] = NULL;
|
|
}
|
|
#endif
|
|
error = fd;
|
|
|
|
out:
|
|
spin_unlock(&files->file_lock);
|
|
return error;
|
|
}
|
|
|
|
int get_unused_fd(void)
|
|
{
|
|
return get_unused_fd_flags(0);
|
|
}
|
|
|
|
EXPORT_SYMBOL(get_unused_fd);
|
|
|
|
static void __put_unused_fd(struct files_struct *files, unsigned int fd)
|
|
{
|
|
struct fdtable *fdt = files_fdtable(files);
|
|
__FD_CLR(fd, fdt->open_fds);
|
|
if (fd < files->next_fd)
|
|
files->next_fd = fd;
|
|
}
|
|
|
|
void fastcall put_unused_fd(unsigned int fd)
|
|
{
|
|
struct files_struct *files = current->files;
|
|
spin_lock(&files->file_lock);
|
|
__put_unused_fd(files, fd);
|
|
spin_unlock(&files->file_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL(put_unused_fd);
|
|
|
|
/*
|
|
* Install a file pointer in the fd array.
|
|
*
|
|
* The VFS is full of places where we drop the files lock between
|
|
* setting the open_fds bitmap and installing the file in the file
|
|
* array. At any such point, we are vulnerable to a dup2() race
|
|
* installing a file in the array before us. We need to detect this and
|
|
* fput() the struct file we are about to overwrite in this case.
|
|
*
|
|
* It should never happen - if we allow dup2() do it, _really_ bad things
|
|
* will follow.
|
|
*/
|
|
|
|
void fastcall fd_install(unsigned int fd, struct file * file)
|
|
{
|
|
struct files_struct *files = current->files;
|
|
struct fdtable *fdt;
|
|
spin_lock(&files->file_lock);
|
|
fdt = files_fdtable(files);
|
|
BUG_ON(fdt->fd[fd] != NULL);
|
|
rcu_assign_pointer(fdt->fd[fd], file);
|
|
spin_unlock(&files->file_lock);
|
|
}
|
|
|
|
EXPORT_SYMBOL(fd_install);
|
|
|
|
long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
|
|
{
|
|
char *tmp = getname(filename);
|
|
int fd = PTR_ERR(tmp);
|
|
|
|
if (!IS_ERR(tmp)) {
|
|
fd = get_unused_fd_flags(flags);
|
|
if (fd >= 0) {
|
|
struct file *f = do_filp_open(dfd, tmp, flags, mode);
|
|
if (IS_ERR(f)) {
|
|
put_unused_fd(fd);
|
|
fd = PTR_ERR(f);
|
|
} else {
|
|
fsnotify_open(f->f_path.dentry);
|
|
fd_install(fd, f);
|
|
}
|
|
}
|
|
putname(tmp);
|
|
}
|
|
return fd;
|
|
}
|
|
|
|
asmlinkage long sys_open(const char __user *filename, int flags, int mode)
|
|
{
|
|
long ret;
|
|
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
|
|
ret = do_sys_open(AT_FDCWD, filename, flags, mode);
|
|
/* avoid REGPARM breakage on x86: */
|
|
prevent_tail_call(ret);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(sys_open);
|
|
|
|
asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
|
|
int mode)
|
|
{
|
|
long ret;
|
|
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
|
|
ret = do_sys_open(dfd, filename, flags, mode);
|
|
/* avoid REGPARM breakage on x86: */
|
|
prevent_tail_call(ret);
|
|
return ret;
|
|
}
|
|
|
|
#ifndef __alpha__
|
|
|
|
/*
|
|
* For backward compatibility? Maybe this should be moved
|
|
* into arch/i386 instead?
|
|
*/
|
|
asmlinkage long sys_creat(const char __user * pathname, int mode)
|
|
{
|
|
return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
* "id" is the POSIX thread ID. We use the
|
|
* files pointer for this..
|
|
*/
|
|
int filp_close(struct file *filp, fl_owner_t id)
|
|
{
|
|
int retval = 0;
|
|
|
|
if (!file_count(filp)) {
|
|
printk(KERN_ERR "VFS: Close: file count is 0\n");
|
|
return 0;
|
|
}
|
|
|
|
if (filp->f_op && filp->f_op->flush)
|
|
retval = filp->f_op->flush(filp, id);
|
|
|
|
dnotify_flush(filp, id);
|
|
locks_remove_posix(filp, id);
|
|
fput(filp);
|
|
return retval;
|
|
}
|
|
|
|
EXPORT_SYMBOL(filp_close);
|
|
|
|
/*
|
|
* Careful here! We test whether the file pointer is NULL before
|
|
* releasing the fd. This ensures that one clone task can't release
|
|
* an fd while another clone is opening it.
|
|
*/
|
|
asmlinkage long sys_close(unsigned int fd)
|
|
{
|
|
struct file * filp;
|
|
struct files_struct *files = current->files;
|
|
struct fdtable *fdt;
|
|
int retval;
|
|
|
|
spin_lock(&files->file_lock);
|
|
fdt = files_fdtable(files);
|
|
if (fd >= fdt->max_fds)
|
|
goto out_unlock;
|
|
filp = fdt->fd[fd];
|
|
if (!filp)
|
|
goto out_unlock;
|
|
rcu_assign_pointer(fdt->fd[fd], NULL);
|
|
FD_CLR(fd, fdt->close_on_exec);
|
|
__put_unused_fd(files, fd);
|
|
spin_unlock(&files->file_lock);
|
|
retval = filp_close(filp, files);
|
|
|
|
/* can't restart close syscall because file table entry was cleared */
|
|
if (unlikely(retval == -ERESTARTSYS ||
|
|
retval == -ERESTARTNOINTR ||
|
|
retval == -ERESTARTNOHAND ||
|
|
retval == -ERESTART_RESTARTBLOCK))
|
|
retval = -EINTR;
|
|
|
|
return retval;
|
|
|
|
out_unlock:
|
|
spin_unlock(&files->file_lock);
|
|
return -EBADF;
|
|
}
|
|
|
|
EXPORT_SYMBOL(sys_close);
|
|
|
|
/*
|
|
* This routine simulates a hangup on the tty, to arrange that users
|
|
* are given clean terminals at login time.
|
|
*/
|
|
asmlinkage long sys_vhangup(void)
|
|
{
|
|
if (capable(CAP_SYS_TTY_CONFIG)) {
|
|
/* XXX: this needs locking */
|
|
tty_vhangup(current->signal->tty);
|
|
return 0;
|
|
}
|
|
return -EPERM;
|
|
}
|
|
|
|
/*
|
|
* Called when an inode is about to be open.
|
|
* We use this to disallow opening large files on 32bit systems if
|
|
* the caller didn't specify O_LARGEFILE. On 64bit systems we force
|
|
* on this flag in sys_open.
|
|
*/
|
|
int generic_file_open(struct inode * inode, struct file * filp)
|
|
{
|
|
if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
|
|
return -EFBIG;
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_open);
|
|
|
|
/*
|
|
* This is used by subsystems that don't want seekable
|
|
* file descriptors
|
|
*/
|
|
int nonseekable_open(struct inode *inode, struct file *filp)
|
|
{
|
|
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(nonseekable_open);
|