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9d11b5b5b3
freebsd-skq/sys/kern/kern_descrip.c
jhb 411d068395 Rework the lifetime management of the kernel implementation of POSIX 
semaphores.  Specifically, semaphores are now represented as new file
descriptor type that is set to close on exec.  This removes the need for
all of the manual process reference counting (and fork, exec, and exit
event handlers) as the normal file descriptor operations handle all of
that for us nicely.  It is also suggested as one possible implementation
in the spec and at least one other OS (OS X) uses this approach.

Some bugs that were fixed as a result include:
- References to a named semaphore whose name is removed still work after
  the sem_unlink() operation.  Prior to this patch, if a semaphore's name
  was removed, valid handles from sem_open() would get EINVAL errors from
  sem_getvalue(), sem_post(), etc.  This fixes that.
- Unnamed semaphores created with sem_init() were not cleaned up when a
  process exited or exec'd.  They were only cleaned up if the process
  did an explicit sem_destroy().  This could result in a leak of semaphore
  objects that could never be cleaned up.
- On the other hand, if another process guessed the id (kernel pointer to
  'struct ksem' of an unnamed semaphore (created via sem_init)) and had
  write access to the semaphore based on UID/GID checks, then that other
  process could manipulate the semaphore via sem_destroy(), sem_post(),
  sem_wait(), etc.
- As part of the permission check (UID/GID), the umask of the proces
  creating the semaphore was not honored.  Thus if your umask denied group
  read/write access but the explicit mode in the sem_init() call allowed
  it, the semaphore would be readable/writable by other users in the
  same group, for example.  This includes access via the previous bug.
- If the module refused to unload because there were active semaphores,
  then it might have deregistered one or more of the semaphore system
  calls before it noticed that there was a problem.  I'm not sure if
  this actually happened as the order that modules are discovered by the
  kernel linker depends on how the actual .ko file is linked.  One can
  make the order deterministic by using a single module with a mod_event
  handler that explicitly registers syscalls (and deregisters during
  unload after any checks).  This also fixes a race where even if the
  sem_module unloaded first it would have destroyed locks that the
  syscalls might be trying to access if they are still executing when
  they are unloaded.

  XXX: By the way, deregistering system calls doesn't do any blocking
  to drain any threads from the calls.
- Some minor fixes to errno values on error.  For example, sem_init()
  isn't documented to return ENFILE or EMFILE if we run out of semaphores
  the way that sem_open() can.  Instead, it should return ENOSPC in that
  case.

Other changes:
- Kernel semaphores now use a hash table to manage the namespace of
  named semaphores nearly in a similar fashion to the POSIX shared memory
  object file descriptors.  Kernel semaphores can now also have names
  longer than 14 chars (up to MAXPATHLEN) and can include subdirectories
  in their pathname.
- The UID/GID permission checks for access to a named semaphore are now
  done via vaccess() rather than a home-rolled set of checks.
- Now that kernel semaphores have an associated file object, the various
  MAC checks for POSIX semaphores accept both a file credential and an
  active credential.  There is also a new posixsem_check_stat() since it
  is possible to fstat() a semaphore file descriptor.
- A small set of regression tests (using the ksem API directly) is present
  in src/tools/regression/posixsem.

Reported by:	kris (1)
Tested by:	kris
Reviewed by:	rwatson (lightly)
MFC after:	1 month
2008-06-27 05:39:04 +00:00

2994 lines
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/*-
* Copyright (c) 1982, 1986, 1989, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_descrip.c 8.6 (Berkeley) 4/19/94
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#include "opt_ddb.h"
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/domain.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/filio.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mqueue.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/socketvar.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/unistd.h>
#include <sys/user.h>
#include <sys/vnode.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.h>
#include <vm/uma.h>
#include <ddb/ddb.h>
static MALLOC_DEFINE(M_FILEDESC, "filedesc", "Open file descriptor table");
static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "filedesc_to_leader",
"file desc to leader structures");
static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
static uma_zone_t file_zone;
/* Flags for do_dup() */
#define DUP_FIXED 0x1 /* Force fixed allocation */
#define DUP_FCNTL 0x2 /* fcntl()-style errors */
static int do_dup(struct thread *td, int flags, int old, int new,
register_t *retval);
static int fd_first_free(struct filedesc *, int, int);
static int fd_last_used(struct filedesc *, int, int);
static void fdgrowtable(struct filedesc *, int);
static void fdunused(struct filedesc *fdp, int fd);
static void fdused(struct filedesc *fdp, int fd);
/*
* A process is initially started out with NDFILE descriptors stored within
* this structure, selected to be enough for typical applications based on
* the historical limit of 20 open files (and the usage of descriptors by
* shells). If these descriptors are exhausted, a larger descriptor table
* may be allocated, up to a process' resource limit; the internal arrays
* are then unused.
*/
#define NDFILE 20
#define NDSLOTSIZE sizeof(NDSLOTTYPE)
#define NDENTRIES (NDSLOTSIZE * __CHAR_BIT)
#define NDSLOT(x) ((x) / NDENTRIES)
#define NDBIT(x) ((NDSLOTTYPE)1 << ((x) % NDENTRIES))
#define NDSLOTS(x) (((x) + NDENTRIES - 1) / NDENTRIES)
/*
* Storage required per open file descriptor.
*/
#define OFILESIZE (sizeof(struct file *) + sizeof(char))
/*
* Basic allocation of descriptors:
* one of the above, plus arrays for NDFILE descriptors.
*/
struct filedesc0 {
struct filedesc fd_fd;
/*
* These arrays are used when the number of open files is
* <= NDFILE, and are then pointed to by the pointers above.
*/
struct file *fd_dfiles[NDFILE];
char fd_dfileflags[NDFILE];
NDSLOTTYPE fd_dmap[NDSLOTS(NDFILE)];
};
/*
* Descriptor management.
*/
volatile int openfiles; /* actual number of open files */
struct mtx sigio_lock; /* mtx to protect pointers to sigio */
void (*mq_fdclose)(struct thread *td, int fd, struct file *fp);
/* A mutex to protect the association between a proc and filedesc. */
static struct mtx fdesc_mtx;
/*
* Find the first zero bit in the given bitmap, starting at low and not
* exceeding size - 1.
*/
static int
fd_first_free(struct filedesc *fdp, int low, int size)
{
NDSLOTTYPE *map = fdp->fd_map;
NDSLOTTYPE mask;
int off, maxoff;
if (low >= size)
return (low);
off = NDSLOT(low);
if (low % NDENTRIES) {
mask = ~(~(NDSLOTTYPE)0 >> (NDENTRIES - (low % NDENTRIES)));
if ((mask &= ~map[off]) != 0UL)
return (off * NDENTRIES + ffsl(mask) - 1);
++off;
}
for (maxoff = NDSLOTS(size); off < maxoff; ++off)
if (map[off] != ~0UL)
return (off * NDENTRIES + ffsl(~map[off]) - 1);
return (size);
}
/*
* Find the highest non-zero bit in the given bitmap, starting at low and
* not exceeding size - 1.
*/
static int
fd_last_used(struct filedesc *fdp, int low, int size)
{
NDSLOTTYPE *map = fdp->fd_map;
NDSLOTTYPE mask;
int off, minoff;
if (low >= size)
return (-1);
off = NDSLOT(size);
if (size % NDENTRIES) {
mask = ~(~(NDSLOTTYPE)0 << (size % NDENTRIES));
if ((mask &= map[off]) != 0)
return (off * NDENTRIES + flsl(mask) - 1);
--off;
}
for (minoff = NDSLOT(low); off >= minoff; --off)
if (map[off] != 0)
return (off * NDENTRIES + flsl(map[off]) - 1);
return (low - 1);
}
static int
fdisused(struct filedesc *fdp, int fd)
{
KASSERT(fd >= 0 && fd < fdp->fd_nfiles,
("file descriptor %d out of range (0, %d)", fd, fdp->fd_nfiles));
return ((fdp->fd_map[NDSLOT(fd)] & NDBIT(fd)) != 0);
}
/*
* Mark a file descriptor as used.
*/
static void
fdused(struct filedesc *fdp, int fd)
{
FILEDESC_XLOCK_ASSERT(fdp);
KASSERT(!fdisused(fdp, fd),
("fd already used"));
fdp->fd_map[NDSLOT(fd)] |= NDBIT(fd);
if (fd > fdp->fd_lastfile)
fdp->fd_lastfile = fd;
if (fd == fdp->fd_freefile)
fdp->fd_freefile = fd_first_free(fdp, fd, fdp->fd_nfiles);
}
/*
* Mark a file descriptor as unused.
*/
static void
fdunused(struct filedesc *fdp, int fd)
{
FILEDESC_XLOCK_ASSERT(fdp);
KASSERT(fdisused(fdp, fd),
("fd is already unused"));
KASSERT(fdp->fd_ofiles[fd] == NULL,
("fd is still in use"));
fdp->fd_map[NDSLOT(fd)] &= ~NDBIT(fd);
if (fd < fdp->fd_freefile)
fdp->fd_freefile = fd;
if (fd == fdp->fd_lastfile)
fdp->fd_lastfile = fd_last_used(fdp, 0, fd);
}
/*
* System calls on descriptors.
*/
#ifndef _SYS_SYSPROTO_H_
struct getdtablesize_args {
int dummy;
};
#endif
/* ARGSUSED */
int
getdtablesize(struct thread *td, struct getdtablesize_args *uap)
{
struct proc *p = td->td_proc;
PROC_LOCK(p);
td->td_retval[0] =
min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
PROC_UNLOCK(p);
return (0);
}
/*
* Duplicate a file descriptor to a particular value.
*
* Note: keep in mind that a potential race condition exists when closing
* descriptors from a shared descriptor table (via rfork).
*/
#ifndef _SYS_SYSPROTO_H_
struct dup2_args {
u_int from;
u_int to;
};
#endif
/* ARGSUSED */
int
dup2(struct thread *td, struct dup2_args *uap)
{
return (do_dup(td, DUP_FIXED, (int)uap->from, (int)uap->to,
td->td_retval));
}
/*
* Duplicate a file descriptor.
*/
#ifndef _SYS_SYSPROTO_H_
struct dup_args {
u_int fd;
};
#endif
/* ARGSUSED */
int
dup(struct thread *td, struct dup_args *uap)
{
return (do_dup(td, 0, (int)uap->fd, 0, td->td_retval));
}
/*
* The file control system call.
*/
#ifndef _SYS_SYSPROTO_H_
struct fcntl_args {
int fd;
int cmd;
long arg;
};
#endif
/* ARGSUSED */
int
fcntl(struct thread *td, struct fcntl_args *uap)
{
struct flock fl;
struct oflock ofl;
intptr_t arg;
int error;
int cmd;
error = 0;
cmd = uap->cmd;
switch (uap->cmd) {
case F_OGETLK:
case F_OSETLK:
case F_OSETLKW:
/*
* Convert old flock structure to new.
*/
error = copyin((void *)(intptr_t)uap->arg, &ofl, sizeof(ofl));
fl.l_start = ofl.l_start;
fl.l_len = ofl.l_len;
fl.l_pid = ofl.l_pid;
fl.l_type = ofl.l_type;
fl.l_whence = ofl.l_whence;
fl.l_sysid = 0;
switch (uap->cmd) {
case F_OGETLK:
cmd = F_GETLK;
break;
case F_OSETLK:
cmd = F_SETLK;
break;
case F_OSETLKW:
cmd = F_SETLKW;
break;
}
arg = (intptr_t)&fl;
break;
case F_GETLK:
case F_SETLK:
case F_SETLKW:
case F_SETLK_REMOTE:
error = copyin((void *)(intptr_t)uap->arg, &fl, sizeof(fl));
arg = (intptr_t)&fl;
break;
default:
arg = uap->arg;
break;
}
if (error)
return (error);
error = kern_fcntl(td, uap->fd, cmd, arg);
if (error)
return (error);
if (uap->cmd == F_OGETLK) {
ofl.l_start = fl.l_start;
ofl.l_len = fl.l_len;
ofl.l_pid = fl.l_pid;
ofl.l_type = fl.l_type;
ofl.l_whence = fl.l_whence;
error = copyout(&ofl, (void *)(intptr_t)uap->arg, sizeof(ofl));
} else if (uap->cmd == F_GETLK) {
error = copyout(&fl, (void *)(intptr_t)uap->arg, sizeof(fl));
}
return (error);
}
static inline struct file *
fdtofp(int fd, struct filedesc *fdp)
{
struct file *fp;
FILEDESC_LOCK_ASSERT(fdp);
if ((unsigned)fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[fd]) == NULL)
return (NULL);
return (fp);
}
int
kern_fcntl(struct thread *td, int fd, int cmd, intptr_t arg)
{
struct filedesc *fdp;
struct flock *flp;
struct file *fp;
struct proc *p;
char *pop;
struct vnode *vp;
int error, flg, tmp;
int vfslocked;
vfslocked = 0;
error = 0;
flg = F_POSIX;
p = td->td_proc;
fdp = p->p_fd;
switch (cmd) {
case F_DUPFD:
tmp = arg;
error = do_dup(td, DUP_FCNTL, fd, tmp, td->td_retval);
break;
case F_DUP2FD:
tmp = arg;
error = do_dup(td, DUP_FIXED, fd, tmp, td->td_retval);
break;
case F_GETFD:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
pop = &fdp->fd_ofileflags[fd];
td->td_retval[0] = (*pop & UF_EXCLOSE) ? FD_CLOEXEC : 0;
FILEDESC_SUNLOCK(fdp);
break;
case F_SETFD:
FILEDESC_XLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_XUNLOCK(fdp);
error = EBADF;
break;
}
pop = &fdp->fd_ofileflags[fd];
*pop = (*pop &~ UF_EXCLOSE) |
(arg & FD_CLOEXEC ? UF_EXCLOSE : 0);
FILEDESC_XUNLOCK(fdp);
break;
case F_GETFL:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
td->td_retval[0] = OFLAGS(fp->f_flag);
FILEDESC_SUNLOCK(fdp);
break;
case F_SETFL:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
fhold(fp);
FILEDESC_SUNLOCK(fdp);
do {
tmp = flg = fp->f_flag;
tmp &= ~FCNTLFLAGS;
tmp |= FFLAGS(arg & ~O_ACCMODE) & FCNTLFLAGS;
} while(atomic_cmpset_int(&fp->f_flag, flg, tmp) == 0);
tmp = fp->f_flag & FNONBLOCK;
error = fo_ioctl(fp, FIONBIO, &tmp, td->td_ucred, td);
if (error) {
fdrop(fp, td);
break;
}
tmp = fp->f_flag & FASYNC;
error = fo_ioctl(fp, FIOASYNC, &tmp, td->td_ucred, td);
if (error == 0) {
fdrop(fp, td);
break;
}
atomic_clear_int(&fp->f_flag, FNONBLOCK);
tmp = 0;
(void)fo_ioctl(fp, FIONBIO, &tmp, td->td_ucred, td);
fdrop(fp, td);
break;
case F_GETOWN:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
fhold(fp);
FILEDESC_SUNLOCK(fdp);
error = fo_ioctl(fp, FIOGETOWN, &tmp, td->td_ucred, td);
if (error == 0)
td->td_retval[0] = tmp;
fdrop(fp, td);
break;
case F_SETOWN:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
fhold(fp);
FILEDESC_SUNLOCK(fdp);
tmp = arg;
error = fo_ioctl(fp, FIOSETOWN, &tmp, td->td_ucred, td);
fdrop(fp, td);
break;
case F_SETLK_REMOTE:
error = priv_check(td, PRIV_NFS_LOCKD);
if (error)
return (error);
flg = F_REMOTE;
goto do_setlk;
case F_SETLKW:
flg |= F_WAIT;
/* FALLTHROUGH F_SETLK */
case F_SETLK:
do_setlk:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
if (fp->f_type != DTYPE_VNODE) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
flp = (struct flock *)arg;
if (flp->l_whence == SEEK_CUR) {
if (fp->f_offset < 0 ||
(flp->l_start > 0 &&
fp->f_offset > OFF_MAX - flp->l_start)) {
FILEDESC_SUNLOCK(fdp);
error = EOVERFLOW;
break;
}
flp->l_start += fp->f_offset;
}
/*
* VOP_ADVLOCK() may block.
*/
fhold(fp);
FILEDESC_SUNLOCK(fdp);
vp = fp->f_vnode;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
switch (flp->l_type) {
case F_RDLCK:
if ((fp->f_flag & FREAD) == 0) {
error = EBADF;
break;
}
PROC_LOCK(p->p_leader);
p->p_leader->p_flag |= P_ADVLOCK;
PROC_UNLOCK(p->p_leader);
error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
flp, flg);
break;
case F_WRLCK:
if ((fp->f_flag & FWRITE) == 0) {
error = EBADF;
break;
}
PROC_LOCK(p->p_leader);
p->p_leader->p_flag |= P_ADVLOCK;
PROC_UNLOCK(p->p_leader);
error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
flp, flg);
break;
case F_UNLCK:
error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
flp, flg);
break;
case F_UNLCKSYS:
/*
* Temporary api for testing remote lock
* infrastructure.
*/
if (flg != F_REMOTE) {
error = EINVAL;
break;
}
error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
F_UNLCKSYS, flp, flg);
break;
default:
error = EINVAL;
break;
}
VFS_UNLOCK_GIANT(vfslocked);
vfslocked = 0;
/* Check for race with close */
FILEDESC_SLOCK(fdp);
if ((unsigned) fd >= fdp->fd_nfiles ||
fp != fdp->fd_ofiles[fd]) {
FILEDESC_SUNLOCK(fdp);
flp->l_whence = SEEK_SET;
flp->l_start = 0;
flp->l_len = 0;
flp->l_type = F_UNLCK;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
(void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
F_UNLCK, flp, F_POSIX);
VFS_UNLOCK_GIANT(vfslocked);
vfslocked = 0;
} else
FILEDESC_SUNLOCK(fdp);
fdrop(fp, td);
break;
case F_GETLK:
FILEDESC_SLOCK(fdp);
if ((fp = fdtofp(fd, fdp)) == NULL) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
if (fp->f_type != DTYPE_VNODE) {
FILEDESC_SUNLOCK(fdp);
error = EBADF;
break;
}
flp = (struct flock *)arg;
if (flp->l_type != F_RDLCK && flp->l_type != F_WRLCK &&
flp->l_type != F_UNLCK) {
FILEDESC_SUNLOCK(fdp);
error = EINVAL;
break;
}
if (flp->l_whence == SEEK_CUR) {
if ((flp->l_start > 0 &&
fp->f_offset > OFF_MAX - flp->l_start) ||
(flp->l_start < 0 &&
fp->f_offset < OFF_MIN - flp->l_start)) {
FILEDESC_SUNLOCK(fdp);
error = EOVERFLOW;
break;
}
flp->l_start += fp->f_offset;
}
/*
* VOP_ADVLOCK() may block.
*/
fhold(fp);
FILEDESC_SUNLOCK(fdp);
vp = fp->f_vnode;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK, flp,
F_POSIX);
VFS_UNLOCK_GIANT(vfslocked);
vfslocked = 0;
fdrop(fp, td);
break;
default:
error = EINVAL;
break;
}
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
/*
* Common code for dup, dup2, fcntl(F_DUPFD) and fcntl(F_DUP2FD).
*/
static int
do_dup(struct thread *td, int flags, int old, int new,
register_t *retval)
{
struct filedesc *fdp;
struct proc *p;
struct file *fp;
struct file *delfp;
int error, holdleaders, maxfd;
p = td->td_proc;
fdp = p->p_fd;
/*
* Verify we have a valid descriptor to dup from and possibly to
* dup to. Unlike dup() and dup2(), fcntl()'s F_DUPFD should
* return EINVAL when the new descriptor is out of bounds.
*/
if (old < 0)
return (EBADF);
if (new < 0)
return (flags & DUP_FCNTL ? EINVAL : EBADF);
PROC_LOCK(p);
maxfd = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
PROC_UNLOCK(p);
if (new >= maxfd)
return (flags & DUP_FCNTL ? EINVAL : EMFILE);
FILEDESC_XLOCK(fdp);
if (old >= fdp->fd_nfiles || fdp->fd_ofiles[old] == NULL) {
FILEDESC_XUNLOCK(fdp);
return (EBADF);
}
if (flags & DUP_FIXED && old == new) {
*retval = new;
FILEDESC_XUNLOCK(fdp);
return (0);
}
fp = fdp->fd_ofiles[old];
fhold(fp);
/*
* If the caller specified a file descriptor, make sure the file
* table is large enough to hold it, and grab it. Otherwise, just
* allocate a new descriptor the usual way. Since the filedesc
* lock may be temporarily dropped in the process, we have to look
* out for a race.
*/
if (flags & DUP_FIXED) {
if (new >= fdp->fd_nfiles)
fdgrowtable(fdp, new + 1);
if (fdp->fd_ofiles[new] == NULL)
fdused(fdp, new);
} else {
if ((error = fdalloc(td, new, &new)) != 0) {
FILEDESC_XUNLOCK(fdp);
fdrop(fp, td);
return (error);
}
}
/*
* If the old file changed out from under us then treat it as a
* bad file descriptor. Userland should do its own locking to
* avoid this case.
*/
if (fdp->fd_ofiles[old] != fp) {
/* we've allocated a descriptor which we won't use */
if (fdp->fd_ofiles[new] == NULL)
fdunused(fdp, new);
FILEDESC_XUNLOCK(fdp);
fdrop(fp, td);
return (EBADF);
}
KASSERT(old != new,
("new fd is same as old"));
/*
* Save info on the descriptor being overwritten. We cannot close
* it without introducing an ownership race for the slot, since we
* need to drop the filedesc lock to call closef().
*
* XXX this duplicates parts of close().
*/
delfp = fdp->fd_ofiles[new];
holdleaders = 0;
if (delfp != NULL) {
if (td->td_proc->p_fdtol != NULL) {
/*
* Ask fdfree() to sleep to ensure that all relevant
* process leaders can be traversed in closef().
*/
fdp->fd_holdleaderscount++;
holdleaders = 1;
}
}
/*
* Duplicate the source descriptor
*/
fdp->fd_ofiles[new] = fp;
fdp->fd_ofileflags[new] = fdp->fd_ofileflags[old] &~ UF_EXCLOSE;
if (new > fdp->fd_lastfile)
fdp->fd_lastfile = new;
*retval = new;
/*
* If we dup'd over a valid file, we now own the reference to it
* and must dispose of it using closef() semantics (as if a
* close() were performed on it).
*
* XXX this duplicates parts of close().
*/
if (delfp != NULL) {
knote_fdclose(td, new);
if (delfp->f_type == DTYPE_MQUEUE)
mq_fdclose(td, new, delfp);
FILEDESC_XUNLOCK(fdp);
(void) closef(delfp, td);
if (holdleaders) {
FILEDESC_XLOCK(fdp);
fdp->fd_holdleaderscount--;
if (fdp->fd_holdleaderscount == 0 &&
fdp->fd_holdleaderswakeup != 0) {
fdp->fd_holdleaderswakeup = 0;
wakeup(&fdp->fd_holdleaderscount);
}
FILEDESC_XUNLOCK(fdp);
}
} else {
FILEDESC_XUNLOCK(fdp);
}
return (0);
}
/*
* If sigio is on the list associated with a process or process group,
* disable signalling from the device, remove sigio from the list and
* free sigio.
*/
void
funsetown(struct sigio **sigiop)
{
struct sigio *sigio;
SIGIO_LOCK();
sigio = *sigiop;
if (sigio == NULL) {
SIGIO_UNLOCK();
return;
}
*(sigio->sio_myref) = NULL;
if ((sigio)->sio_pgid < 0) {
struct pgrp *pg = (sigio)->sio_pgrp;
PGRP_LOCK(pg);
SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
sigio, sio_pgsigio);
PGRP_UNLOCK(pg);
} else {
struct proc *p = (sigio)->sio_proc;
PROC_LOCK(p);
SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
sigio, sio_pgsigio);
PROC_UNLOCK(p);
}
SIGIO_UNLOCK();
crfree(sigio->sio_ucred);
FREE(sigio, M_SIGIO);
}
/*
* Free a list of sigio structures.
* We only need to lock the SIGIO_LOCK because we have made ourselves
* inaccessible to callers of fsetown and therefore do not need to lock
* the proc or pgrp struct for the list manipulation.
*/
void
funsetownlst(struct sigiolst *sigiolst)
{
struct proc *p;
struct pgrp *pg;
struct sigio *sigio;
sigio = SLIST_FIRST(sigiolst);
if (sigio == NULL)
return;
p = NULL;
pg = NULL;
/*
* Every entry of the list should belong
* to a single proc or pgrp.
*/
if (sigio->sio_pgid < 0) {
pg = sigio->sio_pgrp;
PGRP_LOCK_ASSERT(pg, MA_NOTOWNED);
} else /* if (sigio->sio_pgid > 0) */ {
p = sigio->sio_proc;
PROC_LOCK_ASSERT(p, MA_NOTOWNED);
}
SIGIO_LOCK();
while ((sigio = SLIST_FIRST(sigiolst)) != NULL) {
*(sigio->sio_myref) = NULL;
if (pg != NULL) {
KASSERT(sigio->sio_pgid < 0,
("Proc sigio in pgrp sigio list"));
KASSERT(sigio->sio_pgrp == pg,
("Bogus pgrp in sigio list"));
PGRP_LOCK(pg);
SLIST_REMOVE(&pg->pg_sigiolst, sigio, sigio,
sio_pgsigio);
PGRP_UNLOCK(pg);
} else /* if (p != NULL) */ {
KASSERT(sigio->sio_pgid > 0,
("Pgrp sigio in proc sigio list"));
KASSERT(sigio->sio_proc == p,
("Bogus proc in sigio list"));
PROC_LOCK(p);
SLIST_REMOVE(&p->p_sigiolst, sigio, sigio,
sio_pgsigio);
PROC_UNLOCK(p);
}
SIGIO_UNLOCK();
crfree(sigio->sio_ucred);
FREE(sigio, M_SIGIO);
SIGIO_LOCK();
}
SIGIO_UNLOCK();
}
/*
* This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
*
* After permission checking, add a sigio structure to the sigio list for
* the process or process group.
*/
int
fsetown(pid_t pgid, struct sigio **sigiop)
{
struct proc *proc;
struct pgrp *pgrp;
struct sigio *sigio;
int ret;
if (pgid == 0) {
funsetown(sigiop);
return (0);
}
ret = 0;
/* Allocate and fill in the new sigio out of locks. */
MALLOC(sigio, struct sigio *, sizeof(struct sigio), M_SIGIO, M_WAITOK);
sigio->sio_pgid = pgid;
sigio->sio_ucred = crhold(curthread->td_ucred);
sigio->sio_myref = sigiop;
sx_slock(&proctree_lock);
if (pgid > 0) {
proc = pfind(pgid);
if (proc == NULL) {
ret = ESRCH;
goto fail;
}
/*
* Policy - Don't allow a process to FSETOWN a process
* in another session.
*
* Remove this test to allow maximum flexibility or
* restrict FSETOWN to the current process or process
* group for maximum safety.
*/
PROC_UNLOCK(proc);
if (proc->p_session != curthread->td_proc->p_session) {
ret = EPERM;
goto fail;
}
pgrp = NULL;
} else /* if (pgid < 0) */ {
pgrp = pgfind(-pgid);
if (pgrp == NULL) {
ret = ESRCH;
goto fail;
}
PGRP_UNLOCK(pgrp);
/*
* Policy - Don't allow a process to FSETOWN a process
* in another session.
*
* Remove this test to allow maximum flexibility or
* restrict FSETOWN to the current process or process
* group for maximum safety.
*/
if (pgrp->pg_session != curthread->td_proc->p_session) {
ret = EPERM;
goto fail;
}
proc = NULL;
}
funsetown(sigiop);
if (pgid > 0) {
PROC_LOCK(proc);
/*
* Since funsetownlst() is called without the proctree
* locked, we need to check for P_WEXIT.
* XXX: is ESRCH correct?
*/
if ((proc->p_flag & P_WEXIT) != 0) {
PROC_UNLOCK(proc);
ret = ESRCH;
goto fail;
}
SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
sigio->sio_proc = proc;
PROC_UNLOCK(proc);
} else {
PGRP_LOCK(pgrp);
SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
sigio->sio_pgrp = pgrp;
PGRP_UNLOCK(pgrp);
}
sx_sunlock(&proctree_lock);
SIGIO_LOCK();
*sigiop = sigio;
SIGIO_UNLOCK();
return (0);
fail:
sx_sunlock(&proctree_lock);
crfree(sigio->sio_ucred);
FREE(sigio, M_SIGIO);
return (ret);
}
/*
* This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
*/
pid_t
fgetown(sigiop)
struct sigio **sigiop;
{
pid_t pgid;
SIGIO_LOCK();
pgid = (*sigiop != NULL) ? (*sigiop)->sio_pgid : 0;
SIGIO_UNLOCK();
return (pgid);
}
/*
* Close a file descriptor.
*/
#ifndef _SYS_SYSPROTO_H_
struct close_args {
int fd;
};
#endif
/* ARGSUSED */
int
close(td, uap)
struct thread *td;
struct close_args *uap;
{
return (kern_close(td, uap->fd));
}
int
kern_close(td, fd)
struct thread *td;
int fd;
{
struct filedesc *fdp;
struct file *fp;
int error;
int holdleaders;
error = 0;
holdleaders = 0;
fdp = td->td_proc->p_fd;
AUDIT_SYSCLOSE(td, fd);
FILEDESC_XLOCK(fdp);
if ((unsigned)fd >= fdp->fd_nfiles ||
(fp = fdp->fd_ofiles[fd]) == NULL) {
FILEDESC_XUNLOCK(fdp);
return (EBADF);
}
fdp->fd_ofiles[fd] = NULL;
fdp->fd_ofileflags[fd] = 0;
fdunused(fdp, fd);
if (td->td_proc->p_fdtol != NULL) {
/*
* Ask fdfree() to sleep to ensure that all relevant
* process leaders can be traversed in closef().
*/
fdp->fd_holdleaderscount++;
holdleaders = 1;
}
/*
* We now hold the fp reference that used to be owned by the
* descriptor array. We have to unlock the FILEDESC *AFTER*
* knote_fdclose to prevent a race of the fd getting opened, a knote
* added, and deleteing a knote for the new fd.
*/
knote_fdclose(td, fd);
if (fp->f_type == DTYPE_MQUEUE)
mq_fdclose(td, fd, fp);
FILEDESC_XUNLOCK(fdp);
error = closef(fp, td);
if (holdleaders) {
FILEDESC_XLOCK(fdp);
fdp->fd_holdleaderscount--;
if (fdp->fd_holdleaderscount == 0 &&
fdp->fd_holdleaderswakeup != 0) {
fdp->fd_holdleaderswakeup = 0;
wakeup(&fdp->fd_holdleaderscount);
}
FILEDESC_XUNLOCK(fdp);
}
return (error);
}
#if defined(COMPAT_43)
/*
* Return status information about a file descriptor.
*/
#ifndef _SYS_SYSPROTO_H_
struct ofstat_args {
int fd;
struct ostat *sb;
};
#endif
/* ARGSUSED */
int
ofstat(struct thread *td, struct ofstat_args *uap)
{
struct ostat oub;
struct stat ub;
int error;
error = kern_fstat(td, uap->fd, &ub);
if (error == 0) {
cvtstat(&ub, &oub);
error = copyout(&oub, uap->sb, sizeof(oub));
}
return (error);
}
#endif /* COMPAT_43 */
/*
* Return status information about a file descriptor.
*/
#ifndef _SYS_SYSPROTO_H_
struct fstat_args {
int fd;
struct stat *sb;
};
#endif
/* ARGSUSED */
int
fstat(struct thread *td, struct fstat_args *uap)
{
struct stat ub;
int error;
error = kern_fstat(td, uap->fd, &ub);
if (error == 0)
error = copyout(&ub, uap->sb, sizeof(ub));
return (error);
}
int
kern_fstat(struct thread *td, int fd, struct stat *sbp)
{
struct file *fp;
int error;
AUDIT_ARG(fd, fd);
if ((error = fget(td, fd, &fp)) != 0)
return (error);
AUDIT_ARG(file, td->td_proc, fp);
error = fo_stat(fp, sbp, td->td_ucred, td);
fdrop(fp, td);
#ifdef KTRACE
if (error == 0 && KTRPOINT(td, KTR_STRUCT))
ktrstat(sbp);
#endif
return (error);
}
/*
* Return status information about a file descriptor.
*/
#ifndef _SYS_SYSPROTO_H_
struct nfstat_args {
int fd;
struct nstat *sb;
};
#endif
/* ARGSUSED */
int
nfstat(struct thread *td, struct nfstat_args *uap)
{
struct nstat nub;
struct stat ub;
int error;
error = kern_fstat(td, uap->fd, &ub);
if (error == 0) {
cvtnstat(&ub, &nub);
error = copyout(&nub, uap->sb, sizeof(nub));
}
return (error);
}
/*
* Return pathconf information about a file descriptor.
*/
#ifndef _SYS_SYSPROTO_H_
struct fpathconf_args {
int fd;
int name;
};
#endif
/* ARGSUSED */
int
fpathconf(struct thread *td, struct fpathconf_args *uap)
{
struct file *fp;
struct vnode *vp;
int error;
if ((error = fget(td, uap->fd, &fp)) != 0)
return (error);
/* If asynchronous I/O is available, it works for all descriptors. */
if (uap->name == _PC_ASYNC_IO) {
td->td_retval[0] = async_io_version;
goto out;
}
vp = fp->f_vnode;
if (vp != NULL) {
int vfslocked;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
error = VOP_PATHCONF(vp, uap->name, td->td_retval);
VOP_UNLOCK(vp, 0);
VFS_UNLOCK_GIANT(vfslocked);
} else if (fp->f_type == DTYPE_PIPE || fp->f_type == DTYPE_SOCKET) {
if (uap->name != _PC_PIPE_BUF) {
error = EINVAL;
} else {
td->td_retval[0] = PIPE_BUF;
error = 0;
}
} else {
error = EOPNOTSUPP;
}
out:
fdrop(fp, td);
return (error);
}
/*
* Grow the file table to accomodate (at least) nfd descriptors. This may
* block and drop the filedesc lock, but it will reacquire it before
* returning.
*/
static void
fdgrowtable(struct filedesc *fdp, int nfd)
{
struct file **ntable;
char *nfileflags;
int nnfiles, onfiles;
NDSLOTTYPE *nmap;
FILEDESC_XLOCK_ASSERT(fdp);
KASSERT(fdp->fd_nfiles > 0,
("zero-length file table"));
/* compute the size of the new table */
onfiles = fdp->fd_nfiles;
nnfiles = NDSLOTS(nfd) * NDENTRIES; /* round up */
if (nnfiles <= onfiles)
/* the table is already large enough */
return;
/* allocate a new table and (if required) new bitmaps */
FILEDESC_XUNLOCK(fdp);
MALLOC(ntable, struct file **, nnfiles * OFILESIZE,
M_FILEDESC, M_ZERO | M_WAITOK);
nfileflags = (char *)&ntable[nnfiles];
if (NDSLOTS(nnfiles) > NDSLOTS(onfiles))
MALLOC(nmap, NDSLOTTYPE *, NDSLOTS(nnfiles) * NDSLOTSIZE,
M_FILEDESC, M_ZERO | M_WAITOK);
else
nmap = NULL;
FILEDESC_XLOCK(fdp);
/*
* We now have new tables ready to go. Since we dropped the
* filedesc lock to call malloc(), watch out for a race.
*/
onfiles = fdp->fd_nfiles;
if (onfiles >= nnfiles) {
/* we lost the race, but that's OK */
free(ntable, M_FILEDESC);
if (nmap != NULL)
free(nmap, M_FILEDESC);
return;
}
bcopy(fdp->fd_ofiles, ntable, onfiles * sizeof(*ntable));
bcopy(fdp->fd_ofileflags, nfileflags, onfiles);
if (onfiles > NDFILE)
free(fdp->fd_ofiles, M_FILEDESC);
fdp->fd_ofiles = ntable;
fdp->fd_ofileflags = nfileflags;
if (NDSLOTS(nnfiles) > NDSLOTS(onfiles)) {
bcopy(fdp->fd_map, nmap, NDSLOTS(onfiles) * sizeof(*nmap));
if (NDSLOTS(onfiles) > NDSLOTS(NDFILE))
free(fdp->fd_map, M_FILEDESC);
fdp->fd_map = nmap;
}
fdp->fd_nfiles = nnfiles;
}
/*
* Allocate a file descriptor for the process.
*/
int
fdalloc(struct thread *td, int minfd, int *result)
{
struct proc *p = td->td_proc;
struct filedesc *fdp = p->p_fd;
int fd = -1, maxfd;
FILEDESC_XLOCK_ASSERT(fdp);
if (fdp->fd_freefile > minfd)
minfd = fdp->fd_freefile;
PROC_LOCK(p);
maxfd = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
PROC_UNLOCK(p);
/*
* Search the bitmap for a free descriptor. If none is found, try
* to grow the file table. Keep at it until we either get a file
* descriptor or run into process or system limits; fdgrowtable()
* may drop the filedesc lock, so we're in a race.
*/
for (;;) {
fd = fd_first_free(fdp, minfd, fdp->fd_nfiles);
if (fd >= maxfd)
return (EMFILE);
if (fd < fdp->fd_nfiles)
break;
fdgrowtable(fdp, min(fdp->fd_nfiles * 2, maxfd));
}
/*
* Perform some sanity checks, then mark the file descriptor as
* used and return it to the caller.
*/
KASSERT(!fdisused(fdp, fd),
("fd_first_free() returned non-free descriptor"));
KASSERT(fdp->fd_ofiles[fd] == NULL,
("free descriptor isn't"));
fdp->fd_ofileflags[fd] = 0; /* XXX needed? */
fdused(fdp, fd);
*result = fd;
return (0);
}
/*
* Check to see whether n user file descriptors are available to the process
* p.
*/
int
fdavail(struct thread *td, int n)
{
struct proc *p = td->td_proc;
struct filedesc *fdp = td->td_proc->p_fd;
struct file **fpp;
int i, lim, last;
FILEDESC_LOCK_ASSERT(fdp);
PROC_LOCK(p);
lim = min((int)lim_cur(p, RLIMIT_NOFILE), maxfilesperproc);
PROC_UNLOCK(p);
if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0)
return (1);
last = min(fdp->fd_nfiles, lim);
fpp = &fdp->fd_ofiles[fdp->fd_freefile];
for (i = last - fdp->fd_freefile; --i >= 0; fpp++) {
if (*fpp == NULL && --n <= 0)
return (1);
}
return (0);
}
/*
* Create a new open file structure and allocate a file decriptor for the
* process that refers to it. We add one reference to the file for the
* descriptor table and one reference for resultfp. This is to prevent us
* being preempted and the entry in the descriptor table closed after we
* release the FILEDESC lock.
*/
int
falloc(struct thread *td, struct file **resultfp, int *resultfd)
{
struct proc *p = td->td_proc;
struct file *fp;
int error, i;
int maxuserfiles = maxfiles - (maxfiles / 20);
static struct timeval lastfail;
static int curfail;
fp = uma_zalloc(file_zone, M_WAITOK | M_ZERO);
if ((openfiles >= maxuserfiles &&
priv_check(td, PRIV_MAXFILES) != 0) ||
openfiles >= maxfiles) {
if (ppsratecheck(&lastfail, &curfail, 1)) {
printf("kern.maxfiles limit exceeded by uid %i, please see tuning(7).\n",
td->td_ucred->cr_ruid);
}
uma_zfree(file_zone, fp);
return (ENFILE);
}
atomic_add_int(&openfiles, 1);
/*
* If the process has file descriptor zero open, add the new file
* descriptor to the list of open files at that point, otherwise
* put it at the front of the list of open files.
*/
refcount_init(&fp->f_count, 1);
if (resultfp)
fhold(fp);
fp->f_cred = crhold(td->td_ucred);
fp->f_ops = &badfileops;
fp->f_data = NULL;
fp->f_vnode = NULL;
FILEDESC_XLOCK(p->p_fd);
if ((error = fdalloc(td, 0, &i))) {
FILEDESC_XUNLOCK(p->p_fd);
fdrop(fp, td);
if (resultfp)
fdrop(fp, td);
return (error);
}
p->p_fd->fd_ofiles[i] = fp;
FILEDESC_XUNLOCK(p->p_fd);
if (resultfp)
*resultfp = fp;
if (resultfd)
*resultfd = i;
return (0);
}
/*
* Build a new filedesc structure from another.
* Copy the current, root, and jail root vnode references.
*/
struct filedesc *
fdinit(struct filedesc *fdp)
{
struct filedesc0 *newfdp;
newfdp = malloc(sizeof *newfdp, M_FILEDESC, M_WAITOK | M_ZERO);
FILEDESC_LOCK_INIT(&newfdp->fd_fd);
if (fdp != NULL) {
FILEDESC_XLOCK(fdp);
newfdp->fd_fd.fd_cdir = fdp->fd_cdir;
if (newfdp->fd_fd.fd_cdir)
VREF(newfdp->fd_fd.fd_cdir);
newfdp->fd_fd.fd_rdir = fdp->fd_rdir;
if (newfdp->fd_fd.fd_rdir)
VREF(newfdp->fd_fd.fd_rdir);
newfdp->fd_fd.fd_jdir = fdp->fd_jdir;
if (newfdp->fd_fd.fd_jdir)
VREF(newfdp->fd_fd.fd_jdir);
FILEDESC_XUNLOCK(fdp);
}
/* Create the file descriptor table. */
newfdp->fd_fd.fd_refcnt = 1;
newfdp->fd_fd.fd_holdcnt = 1;
newfdp->fd_fd.fd_cmask = CMASK;
newfdp->fd_fd.fd_ofiles = newfdp->fd_dfiles;
newfdp->fd_fd.fd_ofileflags = newfdp->fd_dfileflags;
newfdp->fd_fd.fd_nfiles = NDFILE;
newfdp->fd_fd.fd_map = newfdp->fd_dmap;
newfdp->fd_fd.fd_lastfile = -1;
return (&newfdp->fd_fd);
}
static struct filedesc *
fdhold(struct proc *p)
{
struct filedesc *fdp;
mtx_lock(&fdesc_mtx);
fdp = p->p_fd;
if (fdp != NULL)
fdp->fd_holdcnt++;
mtx_unlock(&fdesc_mtx);
return (fdp);
}
static void
fddrop(struct filedesc *fdp)
{
int i;
mtx_lock(&fdesc_mtx);
i = --fdp->fd_holdcnt;
mtx_unlock(&fdesc_mtx);
if (i > 0)
return;
FILEDESC_LOCK_DESTROY(fdp);
FREE(fdp, M_FILEDESC);
}
/*
* Share a filedesc structure.
*/
struct filedesc *
fdshare(struct filedesc *fdp)
{
FILEDESC_XLOCK(fdp);
fdp->fd_refcnt++;
FILEDESC_XUNLOCK(fdp);
return (fdp);
}
/*
* Unshare a filedesc structure, if necessary by making a copy
*/
void
fdunshare(struct proc *p, struct thread *td)
{
FILEDESC_XLOCK(p->p_fd);
if (p->p_fd->fd_refcnt > 1) {
struct filedesc *tmp;
FILEDESC_XUNLOCK(p->p_fd);
tmp = fdcopy(p->p_fd);
fdfree(td);
p->p_fd = tmp;
} else
FILEDESC_XUNLOCK(p->p_fd);
}
/*
* Copy a filedesc structure. A NULL pointer in returns a NULL reference,
* this is to ease callers, not catch errors.
*/
struct filedesc *
fdcopy(struct filedesc *fdp)
{
struct filedesc *newfdp;
int i;
/* Certain daemons might not have file descriptors. */
if (fdp == NULL)
return (NULL);
newfdp = fdinit(fdp);
FILEDESC_SLOCK(fdp);
while (fdp->fd_lastfile >= newfdp->fd_nfiles) {
FILEDESC_SUNLOCK(fdp);
FILEDESC_XLOCK(newfdp);
fdgrowtable(newfdp, fdp->fd_lastfile + 1);
FILEDESC_XUNLOCK(newfdp);
FILEDESC_SLOCK(fdp);
}
/* copy everything except kqueue descriptors */
newfdp->fd_freefile = -1;
for (i = 0; i <= fdp->fd_lastfile; ++i) {
if (fdisused(fdp, i) &&
fdp->fd_ofiles[i]->f_type != DTYPE_KQUEUE) {
newfdp->fd_ofiles[i] = fdp->fd_ofiles[i];
newfdp->fd_ofileflags[i] = fdp->fd_ofileflags[i];
fhold(newfdp->fd_ofiles[i]);
newfdp->fd_lastfile = i;
} else {
if (newfdp->fd_freefile == -1)
newfdp->fd_freefile = i;
}
}
FILEDESC_SUNLOCK(fdp);
FILEDESC_XLOCK(newfdp);
for (i = 0; i <= newfdp->fd_lastfile; ++i)
if (newfdp->fd_ofiles[i] != NULL)
fdused(newfdp, i);
FILEDESC_XUNLOCK(newfdp);
FILEDESC_SLOCK(fdp);
if (newfdp->fd_freefile == -1)
newfdp->fd_freefile = i;
newfdp->fd_cmask = fdp->fd_cmask;
FILEDESC_SUNLOCK(fdp);
return (newfdp);
}
/*
* Release a filedesc structure.
*/
void
fdfree(struct thread *td)
{
struct filedesc *fdp;
struct file **fpp;
int i, locked;
struct filedesc_to_leader *fdtol;
struct file *fp;
struct vnode *cdir, *jdir, *rdir, *vp;
struct flock lf;
/* Certain daemons might not have file descriptors. */
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return;
/* Check for special need to clear POSIX style locks */
fdtol = td->td_proc->p_fdtol;
if (fdtol != NULL) {
FILEDESC_XLOCK(fdp);
KASSERT(fdtol->fdl_refcount > 0,
("filedesc_to_refcount botch: fdl_refcount=%d",
fdtol->fdl_refcount));
if (fdtol->fdl_refcount == 1 &&
(td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
for (i = 0, fpp = fdp->fd_ofiles;
i <= fdp->fd_lastfile;
i++, fpp++) {
if (*fpp == NULL ||
(*fpp)->f_type != DTYPE_VNODE)
continue;
fp = *fpp;
fhold(fp);
FILEDESC_XUNLOCK(fdp);
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
vp = fp->f_vnode;
locked = VFS_LOCK_GIANT(vp->v_mount);
(void) VOP_ADVLOCK(vp,
(caddr_t)td->td_proc->
p_leader,
F_UNLCK,
&lf,
F_POSIX);
VFS_UNLOCK_GIANT(locked);
FILEDESC_XLOCK(fdp);
fdrop(fp, td);
fpp = fdp->fd_ofiles + i;
}
}
retry:
if (fdtol->fdl_refcount == 1) {
if (fdp->fd_holdleaderscount > 0 &&
(td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
/*
* close() or do_dup() has cleared a reference
* in a shared file descriptor table.
*/
fdp->fd_holdleaderswakeup = 1;
sx_sleep(&fdp->fd_holdleaderscount,
FILEDESC_LOCK(fdp), PLOCK, "fdlhold", 0);
goto retry;
}
if (fdtol->fdl_holdcount > 0) {
/*
* Ensure that fdtol->fdl_leader remains
* valid in closef().
*/
fdtol->fdl_wakeup = 1;
sx_sleep(fdtol, FILEDESC_LOCK(fdp), PLOCK,
"fdlhold", 0);
goto retry;
}
}
fdtol->fdl_refcount--;
if (fdtol->fdl_refcount == 0 &&
fdtol->fdl_holdcount == 0) {
fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
} else
fdtol = NULL;
td->td_proc->p_fdtol = NULL;
FILEDESC_XUNLOCK(fdp);
if (fdtol != NULL)
FREE(fdtol, M_FILEDESC_TO_LEADER);
}
FILEDESC_XLOCK(fdp);
i = --fdp->fd_refcnt;
FILEDESC_XUNLOCK(fdp);
if (i > 0)
return;
/*
* We are the last reference to the structure, so we can
* safely assume it will not change out from under us.
*/
fpp = fdp->fd_ofiles;
for (i = fdp->fd_lastfile; i-- >= 0; fpp++) {
if (*fpp)
(void) closef(*fpp, td);
}
FILEDESC_XLOCK(fdp);
/* XXX This should happen earlier. */
mtx_lock(&fdesc_mtx);
td->td_proc->p_fd = NULL;
mtx_unlock(&fdesc_mtx);
if (fdp->fd_nfiles > NDFILE)
FREE(fdp->fd_ofiles, M_FILEDESC);
if (NDSLOTS(fdp->fd_nfiles) > NDSLOTS(NDFILE))
FREE(fdp->fd_map, M_FILEDESC);
fdp->fd_nfiles = 0;
cdir = fdp->fd_cdir;
fdp->fd_cdir = NULL;
rdir = fdp->fd_rdir;
fdp->fd_rdir = NULL;
jdir = fdp->fd_jdir;
fdp->fd_jdir = NULL;
FILEDESC_XUNLOCK(fdp);
if (cdir) {
locked = VFS_LOCK_GIANT(cdir->v_mount);
vrele(cdir);
VFS_UNLOCK_GIANT(locked);
}
if (rdir) {
locked = VFS_LOCK_GIANT(rdir->v_mount);
vrele(rdir);
VFS_UNLOCK_GIANT(locked);
}
if (jdir) {
locked = VFS_LOCK_GIANT(jdir->v_mount);
vrele(jdir);
VFS_UNLOCK_GIANT(locked);
}
fddrop(fdp);
}
/*
* For setugid programs, we don't want to people to use that setugidness
* to generate error messages which write to a file which otherwise would
* otherwise be off-limits to the process. We check for filesystems where
* the vnode can change out from under us after execve (like [lin]procfs).
*
* Since setugidsafety calls this only for fd 0, 1 and 2, this check is
* sufficient. We also don't check for setugidness since we know we are.
*/
static int
is_unsafe(struct file *fp)
{
if (fp->f_type == DTYPE_VNODE) {
struct vnode *vp = fp->f_vnode;
if ((vp->v_vflag & VV_PROCDEP) != 0)
return (1);
}
return (0);
}
/*
* Make this setguid thing safe, if at all possible.
*/
void
setugidsafety(struct thread *td)
{
struct filedesc *fdp;
int i;
/* Certain daemons might not have file descriptors. */
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return;
/*
* Note: fdp->fd_ofiles may be reallocated out from under us while
* we are blocked in a close. Be careful!
*/
FILEDESC_XLOCK(fdp);
for (i = 0; i <= fdp->fd_lastfile; i++) {
if (i > 2)
break;
if (fdp->fd_ofiles[i] && is_unsafe(fdp->fd_ofiles[i])) {
struct file *fp;
knote_fdclose(td, i);
/*
* NULL-out descriptor prior to close to avoid
* a race while close blocks.
*/
fp = fdp->fd_ofiles[i];
fdp->fd_ofiles[i] = NULL;
fdp->fd_ofileflags[i] = 0;
fdunused(fdp, i);
FILEDESC_XUNLOCK(fdp);
(void) closef(fp, td);
FILEDESC_XLOCK(fdp);
}
}
FILEDESC_XUNLOCK(fdp);
}
/*
* If a specific file object occupies a specific file descriptor, close the
* file descriptor entry and drop a reference on the file object. This is a
* convenience function to handle a subsequent error in a function that calls
* falloc() that handles the race that another thread might have closed the
* file descriptor out from under the thread creating the file object.
*/
void
fdclose(struct filedesc *fdp, struct file *fp, int idx, struct thread *td)
{
FILEDESC_XLOCK(fdp);
if (fdp->fd_ofiles[idx] == fp) {
fdp->fd_ofiles[idx] = NULL;
fdunused(fdp, idx);
FILEDESC_XUNLOCK(fdp);
fdrop(fp, td);
} else
FILEDESC_XUNLOCK(fdp);
}
/*
* Close any files on exec?
*/
void
fdcloseexec(struct thread *td)
{
struct filedesc *fdp;
int i;
/* Certain daemons might not have file descriptors. */
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return;
FILEDESC_XLOCK(fdp);
/*
* We cannot cache fd_ofiles or fd_ofileflags since operations
* may block and rip them out from under us.
*/
for (i = 0; i <= fdp->fd_lastfile; i++) {
if (fdp->fd_ofiles[i] != NULL &&
(fdp->fd_ofiles[i]->f_type == DTYPE_MQUEUE ||
(fdp->fd_ofileflags[i] & UF_EXCLOSE))) {
struct file *fp;
knote_fdclose(td, i);
/*
* NULL-out descriptor prior to close to avoid
* a race while close blocks.
*/
fp = fdp->fd_ofiles[i];
fdp->fd_ofiles[i] = NULL;
fdp->fd_ofileflags[i] = 0;
fdunused(fdp, i);
if (fp->f_type == DTYPE_MQUEUE)
mq_fdclose(td, i, fp);
FILEDESC_XUNLOCK(fdp);
(void) closef(fp, td);
FILEDESC_XLOCK(fdp);
}
}
FILEDESC_XUNLOCK(fdp);
}
/*
* It is unsafe for set[ug]id processes to be started with file
* descriptors 0..2 closed, as these descriptors are given implicit
* significance in the Standard C library. fdcheckstd() will create a
* descriptor referencing /dev/null for each of stdin, stdout, and
* stderr that is not already open.
*/
int
fdcheckstd(struct thread *td)
{
struct filedesc *fdp;
register_t retval, save;
int i, error, devnull;
fdp = td->td_proc->p_fd;
if (fdp == NULL)
return (0);
KASSERT(fdp->fd_refcnt == 1, ("the fdtable should not be shared"));
devnull = -1;
error = 0;
for (i = 0; i < 3; i++) {
if (fdp->fd_ofiles[i] != NULL)
continue;
if (devnull < 0) {
save = td->td_retval[0];
error = kern_open(td, "/dev/null", UIO_SYSSPACE,
O_RDWR, 0);
devnull = td->td_retval[0];
KASSERT(devnull == i, ("oof, we didn't get our fd"));
td->td_retval[0] = save;
if (error)
break;
} else {
error = do_dup(td, DUP_FIXED, devnull, i, &retval);
if (error != 0)
break;
}
}
return (error);
}
/*
* Internal form of close. Decrement reference count on file structure.
* Note: td may be NULL when closing a file that was being passed in a
* message.
*
* XXXRW: Giant is not required for the caller, but often will be held; this
* makes it moderately likely the Giant will be recursed in the VFS case.
*/
int
closef(struct file *fp, struct thread *td)
{
struct vnode *vp;
struct flock lf;
struct filedesc_to_leader *fdtol;
struct filedesc *fdp;
/*
* POSIX record locking dictates that any close releases ALL
* locks owned by this process. This is handled by setting
* a flag in the unlock to free ONLY locks obeying POSIX
* semantics, and not to free BSD-style file locks.
* If the descriptor was in a message, POSIX-style locks
* aren't passed with the descriptor, and the thread pointer
* will be NULL. Callers should be careful only to pass a
* NULL thread pointer when there really is no owning
* context that might have locks, or the locks will be
* leaked.
*/
if (fp->f_type == DTYPE_VNODE && td != NULL) {
int vfslocked;
vp = fp->f_vnode;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
if ((td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
(void) VOP_ADVLOCK(vp, (caddr_t)td->td_proc->p_leader,
F_UNLCK, &lf, F_POSIX);
}
fdtol = td->td_proc->p_fdtol;
if (fdtol != NULL) {
/*
* Handle special case where file descriptor table is
* shared between multiple process leaders.
*/
fdp = td->td_proc->p_fd;
FILEDESC_XLOCK(fdp);
for (fdtol = fdtol->fdl_next;
fdtol != td->td_proc->p_fdtol;
fdtol = fdtol->fdl_next) {
if ((fdtol->fdl_leader->p_flag &
P_ADVLOCK) == 0)
continue;
fdtol->fdl_holdcount++;
FILEDESC_XUNLOCK(fdp);
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
lf.l_type = F_UNLCK;
vp = fp->f_vnode;
(void) VOP_ADVLOCK(vp,
(caddr_t)fdtol->fdl_leader,
F_UNLCK, &lf, F_POSIX);
FILEDESC_XLOCK(fdp);
fdtol->fdl_holdcount--;
if (fdtol->fdl_holdcount == 0 &&
fdtol->fdl_wakeup != 0) {
fdtol->fdl_wakeup = 0;
wakeup(fdtol);
}
}
FILEDESC_XUNLOCK(fdp);
}
VFS_UNLOCK_GIANT(vfslocked);
}
return (fdrop(fp, td));
}
/*
* Initialize the file pointer with the specified properties.
*
* The ops are set with release semantics to be certain that the flags, type,
* and data are visible when ops is. This is to prevent ops methods from being
* called with bad data.
*/
void
finit(struct file *fp, u_int flag, short type, void *data, struct fileops *ops)
{
fp->f_data = data;
fp->f_flag = flag;
fp->f_type = type;
atomic_store_rel_ptr((volatile uintptr_t *)&fp->f_ops, (uintptr_t)ops);
}
/*
* Extract the file pointer associated with the specified descriptor for the
* current user process.
*
* If the descriptor doesn't exist, EBADF is returned.
*
* If the descriptor exists but doesn't match 'flags' then return EBADF for
* read attempts and EINVAL for write attempts.
*
* If 'hold' is set (non-zero) the file's refcount will be bumped on return.
* It should be dropped with fdrop(). If it is not set, then the refcount
* will not be bumped however the thread's filedesc struct will be returned
* locked (for fgetsock).
*
* If an error occured the non-zero error is returned and *fpp is set to
* NULL. Otherwise *fpp is set and zero is returned.
*/
static __inline int
_fget(struct thread *td, int fd, struct file **fpp, int flags, int hold)
{
struct filedesc *fdp;
struct file *fp;
*fpp = NULL;
if (td == NULL || (fdp = td->td_proc->p_fd) == NULL)
return (EBADF);
FILEDESC_SLOCK(fdp);
if ((fp = fget_locked(fdp, fd)) == NULL || fp->f_ops == &badfileops) {
FILEDESC_SUNLOCK(fdp);
return (EBADF);
}
/*
* FREAD and FWRITE failure return EBADF as per POSIX.
*
* Only one flag, or 0, may be specified.
*/
if (flags == FREAD && (fp->f_flag & FREAD) == 0) {
FILEDESC_SUNLOCK(fdp);
return (EBADF);
}
if (flags == FWRITE && (fp->f_flag & FWRITE) == 0) {
FILEDESC_SUNLOCK(fdp);
return (EBADF);
}
if (hold) {
fhold(fp);
FILEDESC_SUNLOCK(fdp);
}
*fpp = fp;
return (0);
}
int
fget(struct thread *td, int fd, struct file **fpp)
{
return(_fget(td, fd, fpp, 0, 1));
}
int
fget_read(struct thread *td, int fd, struct file **fpp)
{
return(_fget(td, fd, fpp, FREAD, 1));
}
int
fget_write(struct thread *td, int fd, struct file **fpp)
{
return(_fget(td, fd, fpp, FWRITE, 1));
}
/*
* Like fget() but loads the underlying vnode, or returns an error if the
* descriptor does not represent a vnode. Note that pipes use vnodes but
* never have VM objects. The returned vnode will be vref()'d.
*
* XXX: what about the unused flags ?
*/
static __inline int
_fgetvp(struct thread *td, int fd, struct vnode **vpp, int flags)
{
struct file *fp;
int error;
*vpp = NULL;
if ((error = _fget(td, fd, &fp, flags, 0)) != 0)
return (error);
if (fp->f_vnode == NULL) {
error = EINVAL;
} else {
*vpp = fp->f_vnode;
vref(*vpp);
}
FILEDESC_SUNLOCK(td->td_proc->p_fd);
return (error);
}
int
fgetvp(struct thread *td, int fd, struct vnode **vpp)
{
return (_fgetvp(td, fd, vpp, 0));
}
int
fgetvp_read(struct thread *td, int fd, struct vnode **vpp)
{
return (_fgetvp(td, fd, vpp, FREAD));
}
#ifdef notyet
int
fgetvp_write(struct thread *td, int fd, struct vnode **vpp)
{
return (_fgetvp(td, fd, vpp, FWRITE));
}
#endif
/*
* Like fget() but loads the underlying socket, or returns an error if the
* descriptor does not represent a socket.
*
* We bump the ref count on the returned socket. XXX Also obtain the SX lock
* in the future.
*
* XXXRW: fgetsock() and fputsock() are deprecated, as consumers should rely
* on their file descriptor reference to prevent the socket from being free'd
* during use.
*/
int
fgetsock(struct thread *td, int fd, struct socket **spp, u_int *fflagp)
{
struct file *fp;
int error;
*spp = NULL;
if (fflagp != NULL)
*fflagp = 0;
if ((error = _fget(td, fd, &fp, 0, 0)) != 0)
return (error);
if (fp->f_type != DTYPE_SOCKET) {
error = ENOTSOCK;
} else {
*spp = fp->f_data;
if (fflagp)
*fflagp = fp->f_flag;
SOCK_LOCK(*spp);
soref(*spp);
SOCK_UNLOCK(*spp);
}
FILEDESC_SUNLOCK(td->td_proc->p_fd);
return (error);
}
/*
* Drop the reference count on the socket and XXX release the SX lock in the
* future. The last reference closes the socket.
*
* XXXRW: fputsock() is deprecated, see comment for fgetsock().
*/
void
fputsock(struct socket *so)
{
ACCEPT_LOCK();
SOCK_LOCK(so);
sorele(so);
}
/*
* Handle the last reference to a file being closed.
*/
int
_fdrop(struct file *fp, struct thread *td)
{
int error;
error = 0;
if (fp->f_count != 0)
panic("fdrop: count %d", fp->f_count);
if (fp->f_ops != &badfileops)
error = fo_close(fp, td);
/*
* The f_cdevpriv cannot be assigned non-NULL value while we
* are destroying the file.
*/
if (fp->f_cdevpriv != NULL)
devfs_fpdrop(fp);
atomic_subtract_int(&openfiles, 1);
crfree(fp->f_cred);
uma_zfree(file_zone, fp);
return (error);
}
/*
* Apply an advisory lock on a file descriptor.
*
* Just attempt to get a record lock of the requested type on the entire file
* (l_whence = SEEK_SET, l_start = 0, l_len = 0).
*/
#ifndef _SYS_SYSPROTO_H_
struct flock_args {
int fd;
int how;
};
#endif
/* ARGSUSED */
int
flock(struct thread *td, struct flock_args *uap)
{
struct file *fp;
struct vnode *vp;
struct flock lf;
int vfslocked;
int error;
if ((error = fget(td, uap->fd, &fp)) != 0)
return (error);
if (fp->f_type != DTYPE_VNODE) {
fdrop(fp, td);
return (EOPNOTSUPP);
}
vp = fp->f_vnode;
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
lf.l_whence = SEEK_SET;
lf.l_start = 0;
lf.l_len = 0;
if (uap->how & LOCK_UN) {
lf.l_type = F_UNLCK;
atomic_clear_int(&fp->f_flag, FHASLOCK);
error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
goto done2;
}
if (uap->how & LOCK_EX)
lf.l_type = F_WRLCK;
else if (uap->how & LOCK_SH)
lf.l_type = F_RDLCK;
else {
error = EBADF;
goto done2;
}
atomic_set_int(&fp->f_flag, FHASLOCK);
error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf,
(uap->how & LOCK_NB) ? F_FLOCK : F_FLOCK | F_WAIT);
done2:
fdrop(fp, td);
VFS_UNLOCK_GIANT(vfslocked);
return (error);
}
/*
* Duplicate the specified descriptor to a free descriptor.
*/
int
dupfdopen(struct thread *td, struct filedesc *fdp, int indx, int dfd, int mode, int error)
{
struct file *wfp;
struct file *fp;
/*
* If the to-be-dup'd fd number is greater than the allowed number
* of file descriptors, or the fd to be dup'd has already been
* closed, then reject.
*/
FILEDESC_XLOCK(fdp);
if (dfd < 0 || dfd >= fdp->fd_nfiles ||
(wfp = fdp->fd_ofiles[dfd]) == NULL) {
FILEDESC_XUNLOCK(fdp);
return (EBADF);
}
/*
* There are two cases of interest here.
*
* For ENODEV simply dup (dfd) to file descriptor (indx) and return.
*
* For ENXIO steal away the file structure from (dfd) and store it in
* (indx). (dfd) is effectively closed by this operation.
*
* Any other error code is just returned.
*/
switch (error) {
case ENODEV:
/*
* Check that the mode the file is being opened for is a
* subset of the mode of the existing descriptor.
*/
if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
FILEDESC_XUNLOCK(fdp);
return (EACCES);
}
fp = fdp->fd_ofiles[indx];
fdp->fd_ofiles[indx] = wfp;
fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
if (fp == NULL)
fdused(fdp, indx);
fhold(wfp);
FILEDESC_XUNLOCK(fdp);
if (fp != NULL)
/*
* We now own the reference to fp that the ofiles[]
* array used to own. Release it.
*/
fdrop(fp, td);
return (0);
case ENXIO:
/*
* Steal away the file pointer from dfd and stuff it into indx.
*/
fp = fdp->fd_ofiles[indx];
fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd];
fdp->fd_ofiles[dfd] = NULL;
fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
fdp->fd_ofileflags[dfd] = 0;
fdunused(fdp, dfd);
if (fp == NULL)
fdused(fdp, indx);
FILEDESC_XUNLOCK(fdp);
/*
* We now own the reference to fp that the ofiles[] array
* used to own. Release it.
*/
if (fp != NULL)
fdrop(fp, td);
return (0);
default:
FILEDESC_XUNLOCK(fdp);
return (error);
}
/* NOTREACHED */
}
/*
* Scan all active processes to see if any of them have a current or root
* directory of `olddp'. If so, replace them with the new mount point.
*/
void
mountcheckdirs(struct vnode *olddp, struct vnode *newdp)
{
struct filedesc *fdp;
struct proc *p;
int nrele;
if (vrefcnt(olddp) == 1)
return;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
fdp = fdhold(p);
if (fdp == NULL)
continue;
nrele = 0;
FILEDESC_XLOCK(fdp);
if (fdp->fd_cdir == olddp) {
vref(newdp);
fdp->fd_cdir = newdp;
nrele++;
}
if (fdp->fd_rdir == olddp) {
vref(newdp);
fdp->fd_rdir = newdp;
nrele++;
}
FILEDESC_XUNLOCK(fdp);
fddrop(fdp);
while (nrele--)
vrele(olddp);
}
sx_sunlock(&allproc_lock);
if (rootvnode == olddp) {
vrele(rootvnode);
vref(newdp);
rootvnode = newdp;
}
}
struct filedesc_to_leader *
filedesc_to_leader_alloc(struct filedesc_to_leader *old, struct filedesc *fdp, struct proc *leader)
{
struct filedesc_to_leader *fdtol;
MALLOC(fdtol, struct filedesc_to_leader *,
sizeof(struct filedesc_to_leader),
M_FILEDESC_TO_LEADER,
M_WAITOK);
fdtol->fdl_refcount = 1;
fdtol->fdl_holdcount = 0;
fdtol->fdl_wakeup = 0;
fdtol->fdl_leader = leader;
if (old != NULL) {
FILEDESC_XLOCK(fdp);
fdtol->fdl_next = old->fdl_next;
fdtol->fdl_prev = old;
old->fdl_next = fdtol;
fdtol->fdl_next->fdl_prev = fdtol;
FILEDESC_XUNLOCK(fdp);
} else {
fdtol->fdl_next = fdtol;
fdtol->fdl_prev = fdtol;
}
return (fdtol);
}
/*
* Get file structures globally.
*/
static int
sysctl_kern_file(SYSCTL_HANDLER_ARGS)
{
struct xfile xf;
struct filedesc *fdp;
struct file *fp;
struct proc *p;
int error, n;
error = sysctl_wire_old_buffer(req, 0);
if (error != 0)
return (error);
if (req->oldptr == NULL) {
n = 0;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
if (p->p_state == PRS_NEW)
continue;
fdp = fdhold(p);
if (fdp == NULL)
continue;
/* overestimates sparse tables. */
if (fdp->fd_lastfile > 0)
n += fdp->fd_lastfile;
fddrop(fdp);
}
sx_sunlock(&allproc_lock);
return (SYSCTL_OUT(req, 0, n * sizeof(xf)));
}
error = 0;
bzero(&xf, sizeof(xf));
xf.xf_size = sizeof(xf);
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
if (p->p_state == PRS_NEW)
continue;
PROC_LOCK(p);
if (p_cansee(req->td, p) != 0) {
PROC_UNLOCK(p);
continue;
}
xf.xf_pid = p->p_pid;
xf.xf_uid = p->p_ucred->cr_uid;
PROC_UNLOCK(p);
fdp = fdhold(p);
if (fdp == NULL)
continue;
FILEDESC_SLOCK(fdp);
for (n = 0; fdp->fd_refcnt > 0 && n < fdp->fd_nfiles; ++n) {
if ((fp = fdp->fd_ofiles[n]) == NULL)
continue;
xf.xf_fd = n;
xf.xf_file = fp;
xf.xf_data = fp->f_data;
xf.xf_vnode = fp->f_vnode;
xf.xf_type = fp->f_type;
xf.xf_count = fp->f_count;
xf.xf_msgcount = 0;
xf.xf_offset = fp->f_offset;
xf.xf_flag = fp->f_flag;
error = SYSCTL_OUT(req, &xf, sizeof(xf));
if (error)
break;
}
FILEDESC_SUNLOCK(fdp);
fddrop(fdp);
if (error)
break;
}
sx_sunlock(&allproc_lock);
return (error);
}
SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
0, 0, sysctl_kern_file, "S,xfile", "Entire file table");
static int
export_vnode_for_sysctl(struct vnode *vp, int type,
struct kinfo_file *kif, struct filedesc *fdp, struct sysctl_req *req)
{
int error;
char *fullpath, *freepath;
int vfslocked;
bzero(kif, sizeof(*kif));
kif->kf_structsize = sizeof(*kif);
vref(vp);
kif->kf_fd = type;
kif->kf_type = KF_TYPE_VNODE;
/* This function only handles directories. */
KASSERT(vp->v_type == VDIR, ("export_vnode_for_sysctl: vnode not directory"));
kif->kf_vnode_type = KF_VTYPE_VDIR;
/*
* This is not a true file descriptor, so we set a bogus refcount
* and offset to indicate these fields should be ignored.
*/
kif->kf_ref_count = -1;
kif->kf_offset = -1;
freepath = NULL;
fullpath = "-";
FILEDESC_SUNLOCK(fdp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(curthread, vp, &fullpath, &freepath);
vput(vp);
VFS_UNLOCK_GIANT(vfslocked);
strlcpy(kif->kf_path, fullpath, sizeof(kif->kf_path));
if (freepath != NULL)
free(freepath, M_TEMP);
error = SYSCTL_OUT(req, kif, sizeof(*kif));
FILEDESC_SLOCK(fdp);
return (error);
}
/*
* Get per-process file descriptors for use by procstat(1), et al.
*/
static int
sysctl_kern_proc_filedesc(SYSCTL_HANDLER_ARGS)
{
char *fullpath, *freepath;
struct kinfo_file *kif;
struct filedesc *fdp;
int error, i, *name;
struct socket *so;
struct vnode *vp;
struct file *fp;
struct proc *p;
int vfslocked;
name = (int *)arg1;
if ((p = pfind((pid_t)name[0])) == NULL)
return (ESRCH);
if ((error = p_candebug(curthread, p))) {
PROC_UNLOCK(p);
return (error);
}
fdp = fdhold(p);
PROC_UNLOCK(p);
if (fdp == NULL)
return (ENOENT);
kif = malloc(sizeof(*kif), M_TEMP, M_WAITOK);
FILEDESC_SLOCK(fdp);
if (fdp->fd_cdir != NULL)
export_vnode_for_sysctl(fdp->fd_cdir, KF_FD_TYPE_CWD, kif,
fdp, req);
if (fdp->fd_rdir != NULL)
export_vnode_for_sysctl(fdp->fd_rdir, KF_FD_TYPE_ROOT, kif,
fdp, req);
if (fdp->fd_jdir != NULL)
export_vnode_for_sysctl(fdp->fd_jdir, KF_FD_TYPE_JAIL, kif,
fdp, req);
for (i = 0; i < fdp->fd_nfiles; i++) {
if ((fp = fdp->fd_ofiles[i]) == NULL)
continue;
bzero(kif, sizeof(*kif));
kif->kf_structsize = sizeof(*kif);
vp = NULL;
so = NULL;
kif->kf_fd = i;
switch (fp->f_type) {
case DTYPE_VNODE:
kif->kf_type = KF_TYPE_VNODE;
vp = fp->f_vnode;
break;
case DTYPE_SOCKET:
kif->kf_type = KF_TYPE_SOCKET;
so = fp->f_data;
break;
case DTYPE_PIPE:
kif->kf_type = KF_TYPE_PIPE;
break;
case DTYPE_FIFO:
kif->kf_type = KF_TYPE_FIFO;
vp = fp->f_vnode;
vref(vp);
break;
case DTYPE_KQUEUE:
kif->kf_type = KF_TYPE_KQUEUE;
break;
case DTYPE_CRYPTO:
kif->kf_type = KF_TYPE_CRYPTO;
break;
case DTYPE_MQUEUE:
kif->kf_type = KF_TYPE_MQUEUE;
break;
case DTYPE_SHM:
kif->kf_type = KF_TYPE_SHM;
break;
case DTYPE_SEM:
kif->kf_type = KF_TYPE_SEM;
break;
default:
kif->kf_type = KF_TYPE_UNKNOWN;
break;
}
kif->kf_ref_count = fp->f_count;
if (fp->f_flag & FREAD)
kif->kf_flags |= KF_FLAG_READ;
if (fp->f_flag & FWRITE)
kif->kf_flags |= KF_FLAG_WRITE;
if (fp->f_flag & FAPPEND)
kif->kf_flags |= KF_FLAG_APPEND;
if (fp->f_flag & FASYNC)
kif->kf_flags |= KF_FLAG_ASYNC;
if (fp->f_flag & FFSYNC)
kif->kf_flags |= KF_FLAG_FSYNC;
if (fp->f_flag & FNONBLOCK)
kif->kf_flags |= KF_FLAG_NONBLOCK;
if (fp->f_flag & O_DIRECT)
kif->kf_flags |= KF_FLAG_DIRECT;
if (fp->f_flag & FHASLOCK)
kif->kf_flags |= KF_FLAG_HASLOCK;
kif->kf_offset = fp->f_offset;
if (vp != NULL) {
vref(vp);
switch (vp->v_type) {
case VNON:
kif->kf_vnode_type = KF_VTYPE_VNON;
break;
case VREG:
kif->kf_vnode_type = KF_VTYPE_VREG;
break;
case VDIR:
kif->kf_vnode_type = KF_VTYPE_VDIR;
break;
case VBLK:
kif->kf_vnode_type = KF_VTYPE_VBLK;
break;
case VCHR:
kif->kf_vnode_type = KF_VTYPE_VCHR;
break;
case VLNK:
kif->kf_vnode_type = KF_VTYPE_VLNK;
break;
case VSOCK:
kif->kf_vnode_type = KF_VTYPE_VSOCK;
break;
case VFIFO:
kif->kf_vnode_type = KF_VTYPE_VFIFO;
break;
case VBAD:
kif->kf_vnode_type = KF_VTYPE_VBAD;
break;
default:
kif->kf_vnode_type = KF_VTYPE_UNKNOWN;
break;
}
/*
* It is OK to drop the filedesc lock here as we will
* re-validate and re-evaluate its properties when
* the loop continues.
*/
freepath = NULL;
fullpath = "-";
FILEDESC_SUNLOCK(fdp);
vfslocked = VFS_LOCK_GIANT(vp->v_mount);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
vn_fullpath(curthread, vp, &fullpath, &freepath);
vput(vp);
VFS_UNLOCK_GIANT(vfslocked);
strlcpy(kif->kf_path, fullpath,
sizeof(kif->kf_path));
if (freepath != NULL)
free(freepath, M_TEMP);
FILEDESC_SLOCK(fdp);
}
if (so != NULL) {
struct sockaddr *sa;
if (so->so_proto->pr_usrreqs->pru_sockaddr(so, &sa)
== 0 && sa->sa_len <= sizeof(kif->kf_sa_local)) {
bcopy(sa, &kif->kf_sa_local, sa->sa_len);
free(sa, M_SONAME);
}
if (so->so_proto->pr_usrreqs->pru_peeraddr(so, &sa)
== 00 && sa->sa_len <= sizeof(kif->kf_sa_peer)) {
bcopy(sa, &kif->kf_sa_peer, sa->sa_len);
free(sa, M_SONAME);
}
kif->kf_sock_domain =
so->so_proto->pr_domain->dom_family;
kif->kf_sock_type = so->so_type;
kif->kf_sock_protocol = so->so_proto->pr_protocol;
}
error = SYSCTL_OUT(req, kif, sizeof(*kif));
if (error)
break;
}
FILEDESC_SUNLOCK(fdp);
fddrop(fdp);
free(kif, M_TEMP);
return (0);
}
static SYSCTL_NODE(_kern_proc, KERN_PROC_FILEDESC, filedesc, CTLFLAG_RD,
sysctl_kern_proc_filedesc, "Process filedesc entries");
#ifdef DDB
/*
* For the purposes of debugging, generate a human-readable string for the
* file type.
*/
static const char *
file_type_to_name(short type)
{
switch (type) {
case 0:
return ("zero");
case DTYPE_VNODE:
return ("vnod");
case DTYPE_SOCKET:
return ("sock");
case DTYPE_PIPE:
return ("pipe");
case DTYPE_FIFO:
return ("fifo");
case DTYPE_KQUEUE:
return ("kque");
case DTYPE_CRYPTO:
return ("crpt");
case DTYPE_MQUEUE:
return ("mque");
case DTYPE_SHM:
return ("shm");
case DTYPE_SEM:
return ("ksem");
default:
return ("unkn");
}
}
/*
* For the purposes of debugging, identify a process (if any, perhaps one of
* many) that references the passed file in its file descriptor array. Return
* NULL if none.
*/
static struct proc *
file_to_first_proc(struct file *fp)
{
struct filedesc *fdp;
struct proc *p;
int n;
FOREACH_PROC_IN_SYSTEM(p) {
if (p->p_state == PRS_NEW)
continue;
fdp = p->p_fd;
if (fdp == NULL)
continue;
for (n = 0; n < fdp->fd_nfiles; n++) {
if (fp == fdp->fd_ofiles[n])
return (p);
}
}
return (NULL);
}
static void
db_print_file(struct file *fp, int header)
{
struct proc *p;
if (header)
db_printf("%8s %4s %8s %8s %4s %5s %6s %8s %5s %12s\n",
"File", "Type", "Data", "Flag", "GCFl", "Count",
"MCount", "Vnode", "FPID", "FCmd");
p = file_to_first_proc(fp);
db_printf("%8p %4s %8p %08x %04x %5d %6d %8p %5d %12s\n", fp,
file_type_to_name(fp->f_type), fp->f_data, fp->f_flag,
0, fp->f_count, 0, fp->f_vnode,
p != NULL ? p->p_pid : -1, p != NULL ? p->p_comm : "-");
}
DB_SHOW_COMMAND(file, db_show_file)
{
struct file *fp;
if (!have_addr) {
db_printf("usage: show file <addr>\n");
return;
}
fp = (struct file *)addr;
db_print_file(fp, 1);
}
DB_SHOW_COMMAND(files, db_show_files)
{
struct filedesc *fdp;
struct file *fp;
struct proc *p;
int header;
int n;
header = 1;
FOREACH_PROC_IN_SYSTEM(p) {
if (p->p_state == PRS_NEW)
continue;
if ((fdp = p->p_fd) == NULL)
continue;
for (n = 0; n < fdp->fd_nfiles; ++n) {
if ((fp = fdp->fd_ofiles[n]) == NULL)
continue;
db_print_file(fp, header);
header = 0;
}
}
}
#endif
SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
&maxfilesperproc, 0, "Maximum files allowed open per process");
SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
&maxfiles, 0, "Maximum number of files");
SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
__DEVOLATILE(int *, &openfiles), 0, "System-wide number of open files");
/* ARGSUSED*/
static void
filelistinit(void *dummy)
{
file_zone = uma_zcreate("Files", sizeof(struct file), NULL, NULL,
NULL, NULL, UMA_ALIGN_PTR, 0);
mtx_init(&sigio_lock, "sigio lock", NULL, MTX_DEF);
mtx_init(&fdesc_mtx, "fdesc", NULL, MTX_DEF);
}
SYSINIT(select, SI_SUB_LOCK, SI_ORDER_FIRST, filelistinit, NULL);
/*-------------------------------------------------------------------*/
static int
badfo_readwrite(struct file *fp, struct uio *uio, struct ucred *active_cred, int flags, struct thread *td)
{
return (EBADF);
}
static int
badfo_truncate(struct file *fp, off_t length, struct ucred *active_cred, struct thread *td)
{
return (EINVAL);
}
static int
badfo_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, struct thread *td)
{
return (EBADF);
}
static int
badfo_poll(struct file *fp, int events, struct ucred *active_cred, struct thread *td)
{
return (0);
}
static int
badfo_kqfilter(struct file *fp, struct knote *kn)
{
return (EBADF);
}
static int
badfo_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, struct thread *td)
{
return (EBADF);
}
static int
badfo_close(struct file *fp, struct thread *td)
{
return (EBADF);
}
struct fileops badfileops = {
.fo_read = badfo_readwrite,
.fo_write = badfo_readwrite,
.fo_truncate = badfo_truncate,
.fo_ioctl = badfo_ioctl,
.fo_poll = badfo_poll,
.fo_kqfilter = badfo_kqfilter,
.fo_stat = badfo_stat,
.fo_close = badfo_close,
};
/*-------------------------------------------------------------------*/
/*
* File Descriptor pseudo-device driver (/dev/fd/).
*
* Opening minor device N dup()s the file (if any) connected to file
* descriptor N belonging to the calling process. Note that this driver
* consists of only the ``open()'' routine, because all subsequent
* references to this file will be direct to the other driver.
*
* XXX: we could give this one a cloning event handler if necessary.
*/
/* ARGSUSED */
static int
fdopen(struct cdev *dev, int mode, int type, struct thread *td)
{
/*
* XXX Kludge: set curthread->td_dupfd to contain the value of the
* the file descriptor being sought for duplication. The error
* return ensures that the vnode for this device will be released
* by vn_open. Open will detect this special error and take the
* actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
* will simply report the error.
*/
td->td_dupfd = dev2unit(dev);
return (ENODEV);
}
static struct cdevsw fildesc_cdevsw = {
.d_version = D_VERSION,
.d_flags = D_NEEDGIANT,
.d_open = fdopen,
.d_name = "FD",
};
static void
fildesc_drvinit(void *unused)
{
struct cdev *dev;
dev = make_dev(&fildesc_cdevsw, 0, UID_ROOT, GID_WHEEL, 0666, "fd/0");
make_dev_alias(dev, "stdin");
dev = make_dev(&fildesc_cdevsw, 1, UID_ROOT, GID_WHEEL, 0666, "fd/1");
make_dev_alias(dev, "stdout");
dev = make_dev(&fildesc_cdevsw, 2, UID_ROOT, GID_WHEEL, 0666, "fd/2");
make_dev_alias(dev, "stderr");
}
SYSINIT(fildescdev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, fildesc_drvinit, NULL);
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