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linux-next/fs/fcntl.c
Al Viro ebe559609d fs: get rid of __FMODE_NONOTIFY kludge 
All it takes to get rid of the __FMODE_NONOTIFY kludge is switching
fanotify from anon_inode_getfd() to anon_inode_getfile_fmode() and adding
a dentry_open_nonotify() helper to be used by fanotify on the other path.
That's it - no more weird shit in OPEN_FMODE(), etc.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/linux-fsdevel/20241113043003.GH3387508@ZenIV/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/d1231137e7b661a382459e79a764259509a4115d.1731684329.git.josef@toxicpanda.com
2024-12-09 11:34:29 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/fcntl.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/syscalls.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/sched/task.h>
#include <linux/fs.h>
#include <linux/filelock.h>
#include <linux/file.h>
#include <linux/capability.h>
#include <linux/dnotify.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/pipe_fs_i.h>
#include <linux/security.h>
#include <linux/ptrace.h>
#include <linux/signal.h>
#include <linux/rcupdate.h>
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <linux/memfd.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/rw_hint.h>
#include <linux/poll.h>
#include <asm/siginfo.h>
#include <linux/uaccess.h>
#include "internal.h"
#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
static int setfl(int fd, struct file * filp, unsigned int arg)
{
struct inode * inode = file_inode(filp);
int error = 0;
/*
* O_APPEND cannot be cleared if the file is marked as append-only
* and the file is open for write.
*/
if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
return -EPERM;
/* O_NOATIME can only be set by the owner or superuser */
if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
if (!inode_owner_or_capable(file_mnt_idmap(filp), inode))
return -EPERM;
/* required for strict SunOS emulation */
if (O_NONBLOCK != O_NDELAY)
if (arg & O_NDELAY)
arg |= O_NONBLOCK;
/* Pipe packetized mode is controlled by O_DIRECT flag */
if (!S_ISFIFO(inode->i_mode) &&
(arg & O_DIRECT) &&
!(filp->f_mode & FMODE_CAN_ODIRECT))
return -EINVAL;
if (filp->f_op->check_flags)
error = filp->f_op->check_flags(arg);
if (error)
return error;
/*
* ->fasync() is responsible for setting the FASYNC bit.
*/
if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
if (error < 0)
goto out;
if (error > 0)
error = 0;
}
spin_lock(&filp->f_lock);
filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
filp->f_iocb_flags = iocb_flags(filp);
spin_unlock(&filp->f_lock);
out:
return error;
}
/*
* Allocate an file->f_owner struct if it doesn't exist, handling racing
* allocations correctly.
*/
int file_f_owner_allocate(struct file *file)
{
struct fown_struct *f_owner;
f_owner = file_f_owner(file);
if (f_owner)
return 0;
f_owner = kzalloc(sizeof(struct fown_struct), GFP_KERNEL);
if (!f_owner)
return -ENOMEM;
rwlock_init(&f_owner->lock);
f_owner->file = file;
/* If someone else raced us, drop our allocation. */
if (unlikely(cmpxchg(&file->f_owner, NULL, f_owner)))
kfree(f_owner);
return 0;
}
EXPORT_SYMBOL(file_f_owner_allocate);
void file_f_owner_release(struct file *file)
{
struct fown_struct *f_owner;
f_owner = file_f_owner(file);
if (f_owner) {
put_pid(f_owner->pid);
kfree(f_owner);
}
}
void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
int force)
{
struct fown_struct *f_owner;
f_owner = file_f_owner(filp);
if (WARN_ON_ONCE(!f_owner))
return;
write_lock_irq(&f_owner->lock);
if (force || !f_owner->pid) {
put_pid(f_owner->pid);
f_owner->pid = get_pid(pid);
f_owner->pid_type = type;
if (pid) {
const struct cred *cred = current_cred();
security_file_set_fowner(filp);
f_owner->uid = cred->uid;
f_owner->euid = cred->euid;
}
}
write_unlock_irq(&f_owner->lock);
}
EXPORT_SYMBOL(__f_setown);
int f_setown(struct file *filp, int who, int force)
{
enum pid_type type;
struct pid *pid = NULL;
int ret = 0;
might_sleep();
type = PIDTYPE_TGID;
if (who < 0) {
/* avoid overflow below */
if (who == INT_MIN)
return -EINVAL;
type = PIDTYPE_PGID;
who = -who;
}
ret = file_f_owner_allocate(filp);
if (ret)
return ret;
rcu_read_lock();
if (who) {
pid = find_vpid(who);
if (!pid)
ret = -ESRCH;
}
if (!ret)
__f_setown(filp, pid, type, force);
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL(f_setown);
void f_delown(struct file *filp)
{
__f_setown(filp, NULL, PIDTYPE_TGID, 1);
}
pid_t f_getown(struct file *filp)
{
pid_t pid = 0;
struct fown_struct *f_owner;
f_owner = file_f_owner(filp);
if (!f_owner)
return pid;
read_lock_irq(&f_owner->lock);
rcu_read_lock();
if (pid_task(f_owner->pid, f_owner->pid_type)) {
pid = pid_vnr(f_owner->pid);
if (f_owner->pid_type == PIDTYPE_PGID)
pid = -pid;
}
rcu_read_unlock();
read_unlock_irq(&f_owner->lock);
return pid;
}
static int f_setown_ex(struct file *filp, unsigned long arg)
{
struct f_owner_ex __user *owner_p = (void __user *)arg;
struct f_owner_ex owner;
struct pid *pid;
int type;
int ret;
ret = copy_from_user(&owner, owner_p, sizeof(owner));
if (ret)
return -EFAULT;
switch (owner.type) {
case F_OWNER_TID:
type = PIDTYPE_PID;
break;
case F_OWNER_PID:
type = PIDTYPE_TGID;
break;
case F_OWNER_PGRP:
type = PIDTYPE_PGID;
break;
default:
return -EINVAL;
}
ret = file_f_owner_allocate(filp);
if (ret)
return ret;
rcu_read_lock();
pid = find_vpid(owner.pid);
if (owner.pid && !pid)
ret = -ESRCH;
else
__f_setown(filp, pid, type, 1);
rcu_read_unlock();
return ret;
}
static int f_getown_ex(struct file *filp, unsigned long arg)
{
struct f_owner_ex __user *owner_p = (void __user *)arg;
struct f_owner_ex owner = {};
int ret = 0;
struct fown_struct *f_owner;
enum pid_type pid_type = PIDTYPE_PID;
f_owner = file_f_owner(filp);
if (f_owner) {
read_lock_irq(&f_owner->lock);
rcu_read_lock();
if (pid_task(f_owner->pid, f_owner->pid_type))
owner.pid = pid_vnr(f_owner->pid);
rcu_read_unlock();
pid_type = f_owner->pid_type;
}
switch (pid_type) {
case PIDTYPE_PID:
owner.type = F_OWNER_TID;
break;
case PIDTYPE_TGID:
owner.type = F_OWNER_PID;
break;
case PIDTYPE_PGID:
owner.type = F_OWNER_PGRP;
break;
default:
WARN_ON(1);
ret = -EINVAL;
break;
}
if (f_owner)
read_unlock_irq(&f_owner->lock);
if (!ret) {
ret = copy_to_user(owner_p, &owner, sizeof(owner));
if (ret)
ret = -EFAULT;
}
return ret;
}
#ifdef CONFIG_CHECKPOINT_RESTORE
static int f_getowner_uids(struct file *filp, unsigned long arg)
{
struct user_namespace *user_ns = current_user_ns();
struct fown_struct *f_owner;
uid_t __user *dst = (void __user *)arg;
uid_t src[2] = {0, 0};
int err;
f_owner = file_f_owner(filp);
if (f_owner) {
read_lock_irq(&f_owner->lock);
src[0] = from_kuid(user_ns, f_owner->uid);
src[1] = from_kuid(user_ns, f_owner->euid);
read_unlock_irq(&f_owner->lock);
}
err = put_user(src[0], &dst[0]);
err |= put_user(src[1], &dst[1]);
return err;
}
#else
static int f_getowner_uids(struct file *filp, unsigned long arg)
{
return -EINVAL;
}
#endif
static bool rw_hint_valid(u64 hint)
{
BUILD_BUG_ON(WRITE_LIFE_NOT_SET != RWH_WRITE_LIFE_NOT_SET);
BUILD_BUG_ON(WRITE_LIFE_NONE != RWH_WRITE_LIFE_NONE);
BUILD_BUG_ON(WRITE_LIFE_SHORT != RWH_WRITE_LIFE_SHORT);
BUILD_BUG_ON(WRITE_LIFE_MEDIUM != RWH_WRITE_LIFE_MEDIUM);
BUILD_BUG_ON(WRITE_LIFE_LONG != RWH_WRITE_LIFE_LONG);
BUILD_BUG_ON(WRITE_LIFE_EXTREME != RWH_WRITE_LIFE_EXTREME);
switch (hint) {
case RWH_WRITE_LIFE_NOT_SET:
case RWH_WRITE_LIFE_NONE:
case RWH_WRITE_LIFE_SHORT:
case RWH_WRITE_LIFE_MEDIUM:
case RWH_WRITE_LIFE_LONG:
case RWH_WRITE_LIFE_EXTREME:
return true;
default:
return false;
}
}
static long fcntl_get_rw_hint(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct inode *inode = file_inode(file);
u64 __user *argp = (u64 __user *)arg;
u64 hint = READ_ONCE(inode->i_write_hint);
if (copy_to_user(argp, &hint, sizeof(*argp)))
return -EFAULT;
return 0;
}
static long fcntl_set_rw_hint(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct inode *inode = file_inode(file);
u64 __user *argp = (u64 __user *)arg;
u64 hint;
if (!inode_owner_or_capable(file_mnt_idmap(file), inode))
return -EPERM;
if (copy_from_user(&hint, argp, sizeof(hint)))
return -EFAULT;
if (!rw_hint_valid(hint))
return -EINVAL;
WRITE_ONCE(inode->i_write_hint, hint);
/*
* file->f_mapping->host may differ from inode. As an example,
* blkdev_open() modifies file->f_mapping.
*/
if (file->f_mapping->host != inode)
WRITE_ONCE(file->f_mapping->host->i_write_hint, hint);
return 0;
}
/* Is the file descriptor a dup of the file? */
static long f_dupfd_query(int fd, struct file *filp)
{
CLASS(fd_raw, f)(fd);
if (fd_empty(f))
return -EBADF;
/*
* We can do the 'fdput()' immediately, as the only thing that
* matters is the pointer value which isn't changed by the fdput.
*
* Technically we didn't need a ref at all, and 'fdget()' was
* overkill, but given our lockless file pointer lookup, the
* alternatives are complicated.
*/
return fd_file(f) == filp;
}
/* Let the caller figure out whether a given file was just created. */
static long f_created_query(const struct file *filp)
{
return !!(filp->f_mode & FMODE_CREATED);
}
static int f_owner_sig(struct file *filp, int signum, bool setsig)
{
int ret = 0;
struct fown_struct *f_owner;
might_sleep();
if (setsig) {
if (!valid_signal(signum))
return -EINVAL;
ret = file_f_owner_allocate(filp);
if (ret)
return ret;
}
f_owner = file_f_owner(filp);
if (setsig)
f_owner->signum = signum;
else if (f_owner)
ret = f_owner->signum;
return ret;
}
static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
struct file *filp)
{
void __user *argp = (void __user *)arg;
int argi = (int)arg;
struct flock flock;
long err = -EINVAL;
switch (cmd) {
case F_CREATED_QUERY:
err = f_created_query(filp);
break;
case F_DUPFD:
err = f_dupfd(argi, filp, 0);
break;
case F_DUPFD_CLOEXEC:
err = f_dupfd(argi, filp, O_CLOEXEC);
break;
case F_DUPFD_QUERY:
err = f_dupfd_query(argi, filp);
break;
case F_GETFD:
err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
break;
case F_SETFD:
err = 0;
set_close_on_exec(fd, argi & FD_CLOEXEC);
break;
case F_GETFL:
err = filp->f_flags;
break;
case F_SETFL:
err = setfl(fd, filp, argi);
break;
#if BITS_PER_LONG != 32
/* 32-bit arches must use fcntl64() */
case F_OFD_GETLK:
#endif
case F_GETLK:
if (copy_from_user(&flock, argp, sizeof(flock)))
return -EFAULT;
err = fcntl_getlk(filp, cmd, &flock);
if (!err && copy_to_user(argp, &flock, sizeof(flock)))
return -EFAULT;
break;
#if BITS_PER_LONG != 32
/* 32-bit arches must use fcntl64() */
case F_OFD_SETLK:
case F_OFD_SETLKW:
fallthrough;
#endif
case F_SETLK:
case F_SETLKW:
if (copy_from_user(&flock, argp, sizeof(flock)))
return -EFAULT;
err = fcntl_setlk(fd, filp, cmd, &flock);
break;
case F_GETOWN:
/*
* XXX If f_owner is a process group, the
* negative return value will get converted
* into an error. Oops. If we keep the
* current syscall conventions, the only way
* to fix this will be in libc.
*/
err = f_getown(filp);
force_successful_syscall_return();
break;
case F_SETOWN:
err = f_setown(filp, argi, 1);
break;
case F_GETOWN_EX:
err = f_getown_ex(filp, arg);
break;
case F_SETOWN_EX:
err = f_setown_ex(filp, arg);
break;
case F_GETOWNER_UIDS:
err = f_getowner_uids(filp, arg);
break;
case F_GETSIG:
err = f_owner_sig(filp, 0, false);
break;
case F_SETSIG:
err = f_owner_sig(filp, argi, true);
break;
case F_GETLEASE:
err = fcntl_getlease(filp);
break;
case F_SETLEASE:
err = fcntl_setlease(fd, filp, argi);
break;
case F_NOTIFY:
err = fcntl_dirnotify(fd, filp, argi);
break;
case F_SETPIPE_SZ:
case F_GETPIPE_SZ:
err = pipe_fcntl(filp, cmd, argi);
break;
case F_ADD_SEALS:
case F_GET_SEALS:
err = memfd_fcntl(filp, cmd, argi);
break;
case F_GET_RW_HINT:
err = fcntl_get_rw_hint(filp, cmd, arg);
break;
case F_SET_RW_HINT:
err = fcntl_set_rw_hint(filp, cmd, arg);
break;
default:
break;
}
return err;
}
static int check_fcntl_cmd(unsigned cmd)
{
switch (cmd) {
case F_CREATED_QUERY:
case F_DUPFD:
case F_DUPFD_CLOEXEC:
case F_DUPFD_QUERY:
case F_GETFD:
case F_SETFD:
case F_GETFL:
return 1;
}
return 0;
}
SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
{
CLASS(fd_raw, f)(fd);
long err;
if (fd_empty(f))
return -EBADF;
if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) {
if (!check_fcntl_cmd(cmd))
return -EBADF;
}
err = security_file_fcntl(fd_file(f), cmd, arg);
if (!err)
err = do_fcntl(fd, cmd, arg, fd_file(f));
return err;
}
#if BITS_PER_LONG == 32
SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
unsigned long, arg)
{
void __user *argp = (void __user *)arg;
CLASS(fd_raw, f)(fd);
struct flock64 flock;
long err;
if (fd_empty(f))
return -EBADF;
if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) {
if (!check_fcntl_cmd(cmd))
return -EBADF;
}
err = security_file_fcntl(fd_file(f), cmd, arg);
if (err)
return err;
switch (cmd) {
case F_GETLK64:
case F_OFD_GETLK:
err = -EFAULT;
if (copy_from_user(&flock, argp, sizeof(flock)))
break;
err = fcntl_getlk64(fd_file(f), cmd, &flock);
if (!err && copy_to_user(argp, &flock, sizeof(flock)))
err = -EFAULT;
break;
case F_SETLK64:
case F_SETLKW64:
case F_OFD_SETLK:
case F_OFD_SETLKW:
err = -EFAULT;
if (copy_from_user(&flock, argp, sizeof(flock)))
break;
err = fcntl_setlk64(fd, fd_file(f), cmd, &flock);
break;
default:
err = do_fcntl(fd, cmd, arg, fd_file(f));
break;
}
return err;
}
#endif
#ifdef CONFIG_COMPAT
/* careful - don't use anywhere else */
#define copy_flock_fields(dst, src) \
(dst)->l_type = (src)->l_type; \
(dst)->l_whence = (src)->l_whence; \
(dst)->l_start = (src)->l_start; \
(dst)->l_len = (src)->l_len; \
(dst)->l_pid = (src)->l_pid;
static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl)
{
struct compat_flock fl;
if (copy_from_user(&fl, ufl, sizeof(struct compat_flock)))
return -EFAULT;
copy_flock_fields(kfl, &fl);
return 0;
}
static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl)
{
struct compat_flock64 fl;
if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64)))
return -EFAULT;
copy_flock_fields(kfl, &fl);
return 0;
}
static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl)
{
struct compat_flock fl;
memset(&fl, 0, sizeof(struct compat_flock));
copy_flock_fields(&fl, kfl);
if (copy_to_user(ufl, &fl, sizeof(struct compat_flock)))
return -EFAULT;
return 0;
}
static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl)
{
struct compat_flock64 fl;
BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start));
BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len));
memset(&fl, 0, sizeof(struct compat_flock64));
copy_flock_fields(&fl, kfl);
if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
return -EFAULT;
return 0;
}
#undef copy_flock_fields
static unsigned int
convert_fcntl_cmd(unsigned int cmd)
{
switch (cmd) {
case F_GETLK64:
return F_GETLK;
case F_SETLK64:
return F_SETLK;
case F_SETLKW64:
return F_SETLKW;
}
return cmd;
}
/*
* GETLK was successful and we need to return the data, but it needs to fit in
* the compat structure.
* l_start shouldn't be too big, unless the original start + end is greater than
* COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return
* -EOVERFLOW in that case. l_len could be too big, in which case we just
* truncate it, and only allow the app to see that part of the conflicting lock
* that might make sense to it anyway
*/
static int fixup_compat_flock(struct flock *flock)
{
if (flock->l_start > COMPAT_OFF_T_MAX)
return -EOVERFLOW;
if (flock->l_len > COMPAT_OFF_T_MAX)
flock->l_len = COMPAT_OFF_T_MAX;
return 0;
}
static long do_compat_fcntl64(unsigned int fd, unsigned int cmd,
compat_ulong_t arg)
{
CLASS(fd_raw, f)(fd);
struct flock flock;
long err;
if (fd_empty(f))
return -EBADF;
if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) {
if (!check_fcntl_cmd(cmd))
return -EBADF;
}
err = security_file_fcntl(fd_file(f), cmd, arg);
if (err)
return err;
switch (cmd) {
case F_GETLK:
err = get_compat_flock(&flock, compat_ptr(arg));
if (err)
break;
err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock);
if (err)
break;
err = fixup_compat_flock(&flock);
if (!err)
err = put_compat_flock(&flock, compat_ptr(arg));
break;
case F_GETLK64:
case F_OFD_GETLK:
err = get_compat_flock64(&flock, compat_ptr(arg));
if (err)
break;
err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock);
if (!err)
err = put_compat_flock64(&flock, compat_ptr(arg));
break;
case F_SETLK:
case F_SETLKW:
err = get_compat_flock(&flock, compat_ptr(arg));
if (err)
break;
err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock);
break;
case F_SETLK64:
case F_SETLKW64:
case F_OFD_SETLK:
case F_OFD_SETLKW:
err = get_compat_flock64(&flock, compat_ptr(arg));
if (err)
break;
err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock);
break;
default:
err = do_fcntl(fd, cmd, arg, fd_file(f));
break;
}
return err;
}
COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
compat_ulong_t, arg)
{
return do_compat_fcntl64(fd, cmd, arg);
}
COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
compat_ulong_t, arg)
{
switch (cmd) {
case F_GETLK64:
case F_SETLK64:
case F_SETLKW64:
case F_OFD_GETLK:
case F_OFD_SETLK:
case F_OFD_SETLKW:
return -EINVAL;
}
return do_compat_fcntl64(fd, cmd, arg);
}
#endif
/* Table to convert sigio signal codes into poll band bitmaps */
static const __poll_t band_table[NSIGPOLL] = {
EPOLLIN | EPOLLRDNORM, /* POLL_IN */
EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */
EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */
EPOLLERR, /* POLL_ERR */
EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */
EPOLLHUP | EPOLLERR /* POLL_HUP */
};
static inline int sigio_perm(struct task_struct *p,
struct fown_struct *fown, int sig)
{
const struct cred *cred;
int ret;
rcu_read_lock();
cred = __task_cred(p);
ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) &&
!security_file_send_sigiotask(p, fown, sig));
rcu_read_unlock();
return ret;
}
static void send_sigio_to_task(struct task_struct *p,
struct fown_struct *fown,
int fd, int reason, enum pid_type type)
{
/*
* F_SETSIG can change ->signum lockless in parallel, make
* sure we read it once and use the same value throughout.
*/
int signum = READ_ONCE(fown->signum);
if (!sigio_perm(p, fown, signum))
return;
switch (signum) {
default: {
kernel_siginfo_t si;
/* Queue a rt signal with the appropriate fd as its
value. We use SI_SIGIO as the source, not
SI_KERNEL, since kernel signals always get
delivered even if we can't queue. Failure to
queue in this case _should_ be reported; we fall
back to SIGIO in that case. --sct */
clear_siginfo(&si);
si.si_signo = signum;
si.si_errno = 0;
si.si_code = reason;
/*
* Posix definies POLL_IN and friends to be signal
* specific si_codes for SIG_POLL. Linux extended
* these si_codes to other signals in a way that is
* ambiguous if other signals also have signal
* specific si_codes. In that case use SI_SIGIO instead
* to remove the ambiguity.
*/
if ((signum != SIGPOLL) && sig_specific_sicodes(signum))
si.si_code = SI_SIGIO;
/* Make sure we are called with one of the POLL_*
reasons, otherwise we could leak kernel stack into
userspace. */
BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL));
if (reason - POLL_IN >= NSIGPOLL)
si.si_band = ~0L;
else
si.si_band = mangle_poll(band_table[reason - POLL_IN]);
si.si_fd = fd;
if (!do_send_sig_info(signum, &si, p, type))
break;
}
fallthrough; /* fall back on the old plain SIGIO signal */
case 0:
do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type);
}
}
void send_sigio(struct fown_struct *fown, int fd, int band)
{
struct task_struct *p;
enum pid_type type;
unsigned long flags;
struct pid *pid;
read_lock_irqsave(&fown->lock, flags);
type = fown->pid_type;
pid = fown->pid;
if (!pid)
goto out_unlock_fown;
if (type <= PIDTYPE_TGID) {
rcu_read_lock();
p = pid_task(pid, PIDTYPE_PID);
if (p)
send_sigio_to_task(p, fown, fd, band, type);
rcu_read_unlock();
} else {
read_lock(&tasklist_lock);
do_each_pid_task(pid, type, p) {
send_sigio_to_task(p, fown, fd, band, type);
} while_each_pid_task(pid, type, p);
read_unlock(&tasklist_lock);
}
out_unlock_fown:
read_unlock_irqrestore(&fown->lock, flags);
}
static void send_sigurg_to_task(struct task_struct *p,
struct fown_struct *fown, enum pid_type type)
{
if (sigio_perm(p, fown, SIGURG))
do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type);
}
int send_sigurg(struct file *file)
{
struct fown_struct *fown;
struct task_struct *p;
enum pid_type type;
struct pid *pid;
unsigned long flags;
int ret = 0;
fown = file_f_owner(file);
if (!fown)
return 0;
read_lock_irqsave(&fown->lock, flags);
type = fown->pid_type;
pid = fown->pid;
if (!pid)
goto out_unlock_fown;
ret = 1;
if (type <= PIDTYPE_TGID) {
rcu_read_lock();
p = pid_task(pid, PIDTYPE_PID);
if (p)
send_sigurg_to_task(p, fown, type);
rcu_read_unlock();
} else {
read_lock(&tasklist_lock);
do_each_pid_task(pid, type, p) {
send_sigurg_to_task(p, fown, type);
} while_each_pid_task(pid, type, p);
read_unlock(&tasklist_lock);
}
out_unlock_fown:
read_unlock_irqrestore(&fown->lock, flags);
return ret;
}
static DEFINE_SPINLOCK(fasync_lock);
static struct kmem_cache *fasync_cache __ro_after_init;
/*
* 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;
write_lock_irq(&fa->fa_lock);
fa->fa_file = NULL;
write_unlock_irq(&fa->fa_lock);
*fp = fa->fa_next;
kfree_rcu(fa, fa_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;
write_lock_irq(&fa->fa_lock);
fa->fa_fd = fd;
write_unlock_irq(&fa->fa_lock);
goto out;
}
rwlock_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;
}
read_lock_irqsave(&fa->fa_lock, flags);
if (fa->fa_file) {
fown = file_f_owner(fa->fa_file);
if (!fown)
goto next;
/* 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);
}
next:
read_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(
(VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
__FMODE_EXEC));
fasync_cache = kmem_cache_create("fasync_cache",
sizeof(struct fasync_struct), 0,
SLAB_PANIC | SLAB_ACCOUNT, NULL);
return 0;
}
module_init(fcntl_init)
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