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![Jeff Layton](/assets/img/avatar_default.png)
File-private locks have been merged into Linux for v3.15, and *now* people are commenting that the name and macro definitions for the new file-private locks suck. ...and I can't even disagree. The names and command macros do suck. We're going to have to live with these for a long time, so it's important that we be happy with the names before we're stuck with them. The consensus on the lists so far is that they should be rechristened as "open file description locks". The name isn't a big deal for the kernel, but the command macros are not visually distinct enough from the traditional POSIX lock macros. The glibc and documentation folks are recommending that we change them to look like F_OFD_{GETLK|SETLK|SETLKW}. That lessens the chance that a programmer will typo one of the commands wrong, and also makes it easier to spot this difference when reading code. This patch makes the following changes that I think are necessary before v3.15 ships: 1) rename the command macros to their new names. These end up in the uapi headers and so are part of the external-facing API. It turns out that glibc doesn't actually use the fcntl.h uapi header, but it's hard to be sure that something else won't. Changing it now is safest. 2) make the the /proc/locks output display these as type "OFDLCK" Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Carlos O'Donell <carlos@redhat.com> Cc: Stefan Metzmacher <metze@samba.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Frank Filz <ffilzlnx@mindspring.com> Cc: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jeff Layton <jlayton@redhat.com>
760 lines
17 KiB
C
760 lines
17 KiB
C
/*
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* linux/fs/fcntl.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/syscalls.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/capability.h>
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#include <linux/dnotify.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/pipe_fs_i.h>
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#include <linux/security.h>
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#include <linux/ptrace.h>
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#include <linux/signal.h>
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#include <linux/rcupdate.h>
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#include <linux/pid_namespace.h>
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#include <linux/user_namespace.h>
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#include <asm/poll.h>
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#include <asm/siginfo.h>
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#include <asm/uaccess.h>
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#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
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static int setfl(int fd, struct file * filp, unsigned long arg)
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{
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struct inode * inode = file_inode(filp);
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int error = 0;
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/*
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* O_APPEND cannot be cleared if the file is marked as append-only
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* and the file is open for write.
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*/
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if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
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return -EPERM;
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/* O_NOATIME can only be set by the owner or superuser */
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if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
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if (!inode_owner_or_capable(inode))
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return -EPERM;
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/* required for strict SunOS emulation */
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if (O_NONBLOCK != O_NDELAY)
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if (arg & O_NDELAY)
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arg |= O_NONBLOCK;
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if (arg & O_DIRECT) {
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if (!filp->f_mapping || !filp->f_mapping->a_ops ||
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!filp->f_mapping->a_ops->direct_IO)
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return -EINVAL;
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}
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if (filp->f_op->check_flags)
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error = filp->f_op->check_flags(arg);
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if (error)
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return error;
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/*
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* ->fasync() is responsible for setting the FASYNC bit.
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*/
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if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
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error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
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if (error < 0)
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goto out;
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if (error > 0)
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error = 0;
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}
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spin_lock(&filp->f_lock);
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filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
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spin_unlock(&filp->f_lock);
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out:
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return error;
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}
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static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
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int force)
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{
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write_lock_irq(&filp->f_owner.lock);
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if (force || !filp->f_owner.pid) {
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put_pid(filp->f_owner.pid);
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filp->f_owner.pid = get_pid(pid);
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filp->f_owner.pid_type = type;
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if (pid) {
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const struct cred *cred = current_cred();
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filp->f_owner.uid = cred->uid;
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filp->f_owner.euid = cred->euid;
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}
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}
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write_unlock_irq(&filp->f_owner.lock);
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}
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int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
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int force)
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{
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int err;
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err = security_file_set_fowner(filp);
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if (err)
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return err;
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f_modown(filp, pid, type, force);
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return 0;
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}
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EXPORT_SYMBOL(__f_setown);
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int f_setown(struct file *filp, unsigned long arg, int force)
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{
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enum pid_type type;
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struct pid *pid;
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int who = arg;
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int result;
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type = PIDTYPE_PID;
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if (who < 0) {
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type = PIDTYPE_PGID;
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who = -who;
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}
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rcu_read_lock();
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pid = find_vpid(who);
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result = __f_setown(filp, pid, type, force);
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rcu_read_unlock();
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return result;
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}
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EXPORT_SYMBOL(f_setown);
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void f_delown(struct file *filp)
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{
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f_modown(filp, NULL, PIDTYPE_PID, 1);
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}
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pid_t f_getown(struct file *filp)
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{
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pid_t pid;
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read_lock(&filp->f_owner.lock);
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pid = pid_vnr(filp->f_owner.pid);
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if (filp->f_owner.pid_type == PIDTYPE_PGID)
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pid = -pid;
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read_unlock(&filp->f_owner.lock);
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return pid;
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}
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static int f_setown_ex(struct file *filp, unsigned long arg)
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{
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struct f_owner_ex __user *owner_p = (void __user *)arg;
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struct f_owner_ex owner;
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struct pid *pid;
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int type;
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int ret;
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ret = copy_from_user(&owner, owner_p, sizeof(owner));
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if (ret)
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return -EFAULT;
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switch (owner.type) {
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case F_OWNER_TID:
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type = PIDTYPE_MAX;
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break;
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case F_OWNER_PID:
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type = PIDTYPE_PID;
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break;
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case F_OWNER_PGRP:
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type = PIDTYPE_PGID;
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break;
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default:
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return -EINVAL;
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}
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rcu_read_lock();
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pid = find_vpid(owner.pid);
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if (owner.pid && !pid)
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ret = -ESRCH;
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else
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ret = __f_setown(filp, pid, type, 1);
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rcu_read_unlock();
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return ret;
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}
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static int f_getown_ex(struct file *filp, unsigned long arg)
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{
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struct f_owner_ex __user *owner_p = (void __user *)arg;
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struct f_owner_ex owner;
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int ret = 0;
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read_lock(&filp->f_owner.lock);
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owner.pid = pid_vnr(filp->f_owner.pid);
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switch (filp->f_owner.pid_type) {
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case PIDTYPE_MAX:
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owner.type = F_OWNER_TID;
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break;
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case PIDTYPE_PID:
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owner.type = F_OWNER_PID;
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break;
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case PIDTYPE_PGID:
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owner.type = F_OWNER_PGRP;
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break;
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default:
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WARN_ON(1);
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ret = -EINVAL;
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break;
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}
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read_unlock(&filp->f_owner.lock);
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if (!ret) {
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ret = copy_to_user(owner_p, &owner, sizeof(owner));
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if (ret)
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ret = -EFAULT;
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}
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return ret;
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}
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#ifdef CONFIG_CHECKPOINT_RESTORE
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static int f_getowner_uids(struct file *filp, unsigned long arg)
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{
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struct user_namespace *user_ns = current_user_ns();
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uid_t __user *dst = (void __user *)arg;
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uid_t src[2];
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int err;
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read_lock(&filp->f_owner.lock);
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src[0] = from_kuid(user_ns, filp->f_owner.uid);
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src[1] = from_kuid(user_ns, filp->f_owner.euid);
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read_unlock(&filp->f_owner.lock);
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err = put_user(src[0], &dst[0]);
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err |= put_user(src[1], &dst[1]);
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return err;
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}
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#else
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static int f_getowner_uids(struct file *filp, unsigned long arg)
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{
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return -EINVAL;
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}
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#endif
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static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
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struct file *filp)
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{
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long err = -EINVAL;
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switch (cmd) {
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case F_DUPFD:
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err = f_dupfd(arg, filp, 0);
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break;
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case F_DUPFD_CLOEXEC:
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err = f_dupfd(arg, filp, O_CLOEXEC);
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break;
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case F_GETFD:
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err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
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break;
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case F_SETFD:
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err = 0;
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set_close_on_exec(fd, arg & FD_CLOEXEC);
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break;
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case F_GETFL:
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err = filp->f_flags;
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break;
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case F_SETFL:
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err = setfl(fd, filp, arg);
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break;
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#if BITS_PER_LONG != 32
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/* 32-bit arches must use fcntl64() */
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case F_OFD_GETLK:
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#endif
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case F_GETLK:
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err = fcntl_getlk(filp, cmd, (struct flock __user *) arg);
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break;
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#if BITS_PER_LONG != 32
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/* 32-bit arches must use fcntl64() */
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case F_OFD_SETLK:
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case F_OFD_SETLKW:
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#endif
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/* Fallthrough */
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case F_SETLK:
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case F_SETLKW:
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err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
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break;
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case F_GETOWN:
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/*
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* XXX If f_owner is a process group, the
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* negative return value will get converted
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* into an error. Oops. If we keep the
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* current syscall conventions, the only way
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* to fix this will be in libc.
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*/
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err = f_getown(filp);
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force_successful_syscall_return();
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break;
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case F_SETOWN:
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err = f_setown(filp, arg, 1);
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break;
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case F_GETOWN_EX:
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err = f_getown_ex(filp, arg);
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break;
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case F_SETOWN_EX:
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err = f_setown_ex(filp, arg);
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break;
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case F_GETOWNER_UIDS:
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err = f_getowner_uids(filp, arg);
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break;
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case F_GETSIG:
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err = filp->f_owner.signum;
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break;
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case F_SETSIG:
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/* arg == 0 restores default behaviour. */
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if (!valid_signal(arg)) {
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break;
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}
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err = 0;
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filp->f_owner.signum = arg;
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break;
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case F_GETLEASE:
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err = fcntl_getlease(filp);
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break;
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case F_SETLEASE:
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err = fcntl_setlease(fd, filp, arg);
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break;
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case F_NOTIFY:
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err = fcntl_dirnotify(fd, filp, arg);
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break;
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case F_SETPIPE_SZ:
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case F_GETPIPE_SZ:
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err = pipe_fcntl(filp, cmd, arg);
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break;
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default:
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break;
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}
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return err;
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}
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static int check_fcntl_cmd(unsigned cmd)
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{
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switch (cmd) {
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case F_DUPFD:
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case F_DUPFD_CLOEXEC:
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case F_GETFD:
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case F_SETFD:
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case F_GETFL:
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return 1;
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}
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return 0;
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}
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SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
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{
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struct fd f = fdget_raw(fd);
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long err = -EBADF;
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if (!f.file)
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goto out;
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if (unlikely(f.file->f_mode & FMODE_PATH)) {
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if (!check_fcntl_cmd(cmd))
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goto out1;
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}
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err = security_file_fcntl(f.file, cmd, arg);
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if (!err)
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err = do_fcntl(fd, cmd, arg, f.file);
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out1:
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fdput(f);
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out:
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return err;
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}
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#if BITS_PER_LONG == 32
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SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
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unsigned long, arg)
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{
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struct fd f = fdget_raw(fd);
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long err = -EBADF;
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if (!f.file)
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goto out;
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if (unlikely(f.file->f_mode & FMODE_PATH)) {
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if (!check_fcntl_cmd(cmd))
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goto out1;
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}
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err = security_file_fcntl(f.file, cmd, arg);
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if (err)
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goto out1;
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switch (cmd) {
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case F_GETLK64:
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case F_OFD_GETLK:
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err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg);
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break;
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case F_SETLK64:
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case F_SETLKW64:
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case F_OFD_SETLK:
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case F_OFD_SETLKW:
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err = fcntl_setlk64(fd, f.file, cmd,
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(struct flock64 __user *) arg);
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break;
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default:
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err = do_fcntl(fd, cmd, arg, f.file);
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break;
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}
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out1:
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fdput(f);
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out:
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return err;
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}
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#endif
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/* Table to convert sigio signal codes into poll band bitmaps */
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static const long band_table[NSIGPOLL] = {
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POLLIN | POLLRDNORM, /* POLL_IN */
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POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
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POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
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POLLERR, /* POLL_ERR */
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POLLPRI | POLLRDBAND, /* POLL_PRI */
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POLLHUP | POLLERR /* POLL_HUP */
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};
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static inline int sigio_perm(struct task_struct *p,
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struct fown_struct *fown, int sig)
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{
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const struct cred *cred;
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int ret;
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rcu_read_lock();
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cred = __task_cred(p);
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ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
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uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
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uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) &&
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!security_file_send_sigiotask(p, fown, sig));
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rcu_read_unlock();
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return ret;
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}
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static void send_sigio_to_task(struct task_struct *p,
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struct fown_struct *fown,
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int fd, int reason, int group)
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{
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/*
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* F_SETSIG can change ->signum lockless in parallel, make
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* sure we read it once and use the same value throughout.
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*/
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int signum = ACCESS_ONCE(fown->signum);
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if (!sigio_perm(p, fown, signum))
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return;
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switch (signum) {
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siginfo_t si;
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default:
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/* Queue a rt signal with the appropriate fd as its
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value. We use SI_SIGIO as the source, not
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SI_KERNEL, since kernel signals always get
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delivered even if we can't queue. Failure to
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queue in this case _should_ be reported; we fall
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back to SIGIO in that case. --sct */
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si.si_signo = signum;
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si.si_errno = 0;
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si.si_code = reason;
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/* Make sure we are called with one of the POLL_*
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reasons, otherwise we could leak kernel stack into
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userspace. */
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BUG_ON((reason & __SI_MASK) != __SI_POLL);
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if (reason - POLL_IN >= NSIGPOLL)
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si.si_band = ~0L;
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else
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si.si_band = band_table[reason - POLL_IN];
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si.si_fd = fd;
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if (!do_send_sig_info(signum, &si, p, group))
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break;
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/* fall-through: fall back on the old plain SIGIO signal */
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case 0:
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do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
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}
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}
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void send_sigio(struct fown_struct *fown, int fd, int band)
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{
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struct task_struct *p;
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enum pid_type type;
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struct pid *pid;
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int group = 1;
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read_lock(&fown->lock);
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type = fown->pid_type;
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|
if (type == PIDTYPE_MAX) {
|
|
group = 0;
|
|
type = PIDTYPE_PID;
|
|
}
|
|
|
|
pid = fown->pid;
|
|
if (!pid)
|
|
goto out_unlock_fown;
|
|
|
|
read_lock(&tasklist_lock);
|
|
do_each_pid_task(pid, type, p) {
|
|
send_sigio_to_task(p, fown, fd, band, group);
|
|
} while_each_pid_task(pid, type, p);
|
|
read_unlock(&tasklist_lock);
|
|
out_unlock_fown:
|
|
read_unlock(&fown->lock);
|
|
}
|
|
|
|
static void send_sigurg_to_task(struct task_struct *p,
|
|
struct fown_struct *fown, int group)
|
|
{
|
|
if (sigio_perm(p, fown, SIGURG))
|
|
do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
|
|
}
|
|
|
|
int send_sigurg(struct fown_struct *fown)
|
|
{
|
|
struct task_struct *p;
|
|
enum pid_type type;
|
|
struct pid *pid;
|
|
int group = 1;
|
|
int ret = 0;
|
|
|
|
read_lock(&fown->lock);
|
|
|
|
type = fown->pid_type;
|
|
if (type == PIDTYPE_MAX) {
|
|
group = 0;
|
|
type = PIDTYPE_PID;
|
|
}
|
|
|
|
pid = fown->pid;
|
|
if (!pid)
|
|
goto out_unlock_fown;
|
|
|
|
ret = 1;
|
|
|
|
read_lock(&tasklist_lock);
|
|
do_each_pid_task(pid, type, p) {
|
|
send_sigurg_to_task(p, fown, group);
|
|
} while_each_pid_task(pid, type, p);
|
|
read_unlock(&tasklist_lock);
|
|
out_unlock_fown:
|
|
read_unlock(&fown->lock);
|
|
return ret;
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(fasync_lock);
|
|
static struct kmem_cache *fasync_cache __read_mostly;
|
|
|
|
static void fasync_free_rcu(struct rcu_head *head)
|
|
{
|
|
kmem_cache_free(fasync_cache,
|
|
container_of(head, struct fasync_struct, fa_rcu));
|
|
}
|
|
|
|
/*
|
|
* Remove a fasync entry. If successfully removed, return
|
|
* positive and clear the FASYNC flag. If no entry exists,
|
|
* do nothing and return 0.
|
|
*
|
|
* NOTE! It is very important that the FASYNC flag always
|
|
* match the state "is the filp on a fasync list".
|
|
*
|
|
*/
|
|
int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
|
|
{
|
|
struct fasync_struct *fa, **fp;
|
|
int result = 0;
|
|
|
|
spin_lock(&filp->f_lock);
|
|
spin_lock(&fasync_lock);
|
|
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
|
|
if (fa->fa_file != filp)
|
|
continue;
|
|
|
|
spin_lock_irq(&fa->fa_lock);
|
|
fa->fa_file = NULL;
|
|
spin_unlock_irq(&fa->fa_lock);
|
|
|
|
*fp = fa->fa_next;
|
|
call_rcu(&fa->fa_rcu, fasync_free_rcu);
|
|
filp->f_flags &= ~FASYNC;
|
|
result = 1;
|
|
break;
|
|
}
|
|
spin_unlock(&fasync_lock);
|
|
spin_unlock(&filp->f_lock);
|
|
return result;
|
|
}
|
|
|
|
struct fasync_struct *fasync_alloc(void)
|
|
{
|
|
return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
|
|
}
|
|
|
|
/*
|
|
* NOTE! This can be used only for unused fasync entries:
|
|
* entries that actually got inserted on the fasync list
|
|
* need to be released by rcu - see fasync_remove_entry.
|
|
*/
|
|
void fasync_free(struct fasync_struct *new)
|
|
{
|
|
kmem_cache_free(fasync_cache, new);
|
|
}
|
|
|
|
/*
|
|
* Insert a new entry into the fasync list. Return the pointer to the
|
|
* old one if we didn't use the new one.
|
|
*
|
|
* NOTE! It is very important that the FASYNC flag always
|
|
* match the state "is the filp on a fasync list".
|
|
*/
|
|
struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
|
|
{
|
|
struct fasync_struct *fa, **fp;
|
|
|
|
spin_lock(&filp->f_lock);
|
|
spin_lock(&fasync_lock);
|
|
for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
|
|
if (fa->fa_file != filp)
|
|
continue;
|
|
|
|
spin_lock_irq(&fa->fa_lock);
|
|
fa->fa_fd = fd;
|
|
spin_unlock_irq(&fa->fa_lock);
|
|
goto out;
|
|
}
|
|
|
|
spin_lock_init(&new->fa_lock);
|
|
new->magic = FASYNC_MAGIC;
|
|
new->fa_file = filp;
|
|
new->fa_fd = fd;
|
|
new->fa_next = *fapp;
|
|
rcu_assign_pointer(*fapp, new);
|
|
filp->f_flags |= FASYNC;
|
|
|
|
out:
|
|
spin_unlock(&fasync_lock);
|
|
spin_unlock(&filp->f_lock);
|
|
return fa;
|
|
}
|
|
|
|
/*
|
|
* Add a fasync entry. Return negative on error, positive if
|
|
* added, and zero if did nothing but change an existing one.
|
|
*/
|
|
static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
|
|
{
|
|
struct fasync_struct *new;
|
|
|
|
new = fasync_alloc();
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* fasync_insert_entry() returns the old (update) entry if
|
|
* it existed.
|
|
*
|
|
* So free the (unused) new entry and return 0 to let the
|
|
* caller know that we didn't add any new fasync entries.
|
|
*/
|
|
if (fasync_insert_entry(fd, filp, fapp, new)) {
|
|
fasync_free(new);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* fasync_helper() is used by almost all character device drivers
|
|
* to set up the fasync queue, and for regular files by the file
|
|
* lease code. It returns negative on error, 0 if it did no changes
|
|
* and positive if it added/deleted the entry.
|
|
*/
|
|
int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
|
|
{
|
|
if (!on)
|
|
return fasync_remove_entry(filp, fapp);
|
|
return fasync_add_entry(fd, filp, fapp);
|
|
}
|
|
|
|
EXPORT_SYMBOL(fasync_helper);
|
|
|
|
/*
|
|
* rcu_read_lock() is held
|
|
*/
|
|
static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
|
|
{
|
|
while (fa) {
|
|
struct fown_struct *fown;
|
|
unsigned long flags;
|
|
|
|
if (fa->magic != FASYNC_MAGIC) {
|
|
printk(KERN_ERR "kill_fasync: bad magic number in "
|
|
"fasync_struct!\n");
|
|
return;
|
|
}
|
|
spin_lock_irqsave(&fa->fa_lock, flags);
|
|
if (fa->fa_file) {
|
|
fown = &fa->fa_file->f_owner;
|
|
/* Don't send SIGURG to processes which have not set a
|
|
queued signum: SIGURG has its own default signalling
|
|
mechanism. */
|
|
if (!(sig == SIGURG && fown->signum == 0))
|
|
send_sigio(fown, fa->fa_fd, band);
|
|
}
|
|
spin_unlock_irqrestore(&fa->fa_lock, flags);
|
|
fa = rcu_dereference(fa->fa_next);
|
|
}
|
|
}
|
|
|
|
void kill_fasync(struct fasync_struct **fp, int sig, int band)
|
|
{
|
|
/* First a quick test without locking: usually
|
|
* the list is empty.
|
|
*/
|
|
if (*fp) {
|
|
rcu_read_lock();
|
|
kill_fasync_rcu(rcu_dereference(*fp), sig, band);
|
|
rcu_read_unlock();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(kill_fasync);
|
|
|
|
static int __init fcntl_init(void)
|
|
{
|
|
/*
|
|
* Please add new bits here to ensure allocation uniqueness.
|
|
* Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
|
|
* is defined as O_NONBLOCK on some platforms and not on others.
|
|
*/
|
|
BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
|
|
O_RDONLY | O_WRONLY | O_RDWR |
|
|
O_CREAT | O_EXCL | O_NOCTTY |
|
|
O_TRUNC | O_APPEND | /* O_NONBLOCK | */
|
|
__O_SYNC | O_DSYNC | FASYNC |
|
|
O_DIRECT | O_LARGEFILE | O_DIRECTORY |
|
|
O_NOFOLLOW | O_NOATIME | O_CLOEXEC |
|
|
__FMODE_EXEC | O_PATH | __O_TMPFILE
|
|
));
|
|
|
|
fasync_cache = kmem_cache_create("fasync_cache",
|
|
sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
|
|
return 0;
|
|
}
|
|
|
|
module_init(fcntl_init)
|