2 * Copyright (c) 2005 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
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71 * @(#)kern_descrip.c 8.6 (Berkeley) 4/19/94
72 * $FreeBSD: src/sys/kern/kern_descrip.c,v 1.81.2.19 2004/02/28 00:43:31 tegge Exp $
73 * $DragonFly: src/sys/kern/kern_descrip.c,v 1.79 2008/08/31 13:18:28 aggelos Exp $
76 #include "opt_compat.h"
77 #include <sys/param.h>
78 #include <sys/systm.h>
79 #include <sys/malloc.h>
80 #include <sys/sysproto.h>
82 #include <sys/device.h>
84 #include <sys/filedesc.h>
85 #include <sys/kernel.h>
86 #include <sys/sysctl.h>
87 #include <sys/vnode.h>
89 #include <sys/nlookup.h>
92 #include <sys/filio.h>
93 #include <sys/fcntl.h>
94 #include <sys/unistd.h>
95 #include <sys/resourcevar.h>
96 #include <sys/event.h>
97 #include <sys/kern_syscall.h>
98 #include <sys/kcore.h>
99 #include <sys/kinfo.h>
103 #include <vm/vm_extern.h>
105 #include <sys/thread2.h>
106 #include <sys/file2.h>
107 #include <sys/spinlock2.h>
108 #include <sys/mplock2.h>
110 static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd);
111 static void fdreserve_locked (struct filedesc *fdp, int fd0, int incr);
112 static struct file *funsetfd_locked (struct filedesc *fdp, int fd);
113 static void ffree(struct file *fp);
115 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
116 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader",
117 "file desc to leader structures");
118 MALLOC_DEFINE(M_FILE, "file", "Open file structure");
119 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
121 static struct krate krate_uidinfo = { .freq = 1 };
123 static d_open_t fdopen;
126 #define CDEV_MAJOR 22
127 static struct dev_ops fildesc_ops = {
128 { "FD", CDEV_MAJOR, 0 },
133 * Descriptor management.
135 static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead);
136 static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin);
137 static int nfiles; /* actual number of open files */
141 * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared.
143 * MPSAFE - must be called with fdp->fd_spin exclusively held
147 fdfixup_locked(struct filedesc *fdp, int fd)
149 if (fd < fdp->fd_freefile) {
150 fdp->fd_freefile = fd;
152 while (fdp->fd_lastfile >= 0 &&
153 fdp->fd_files[fdp->fd_lastfile].fp == NULL &&
154 fdp->fd_files[fdp->fd_lastfile].reserved == 0
161 * System calls on descriptors.
166 sys_getdtablesize(struct getdtablesize_args *uap)
168 struct proc *p = curproc;
169 struct plimit *limit = p->p_limit;
172 spin_lock(&limit->p_spin);
173 if (limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
176 dtsize = (int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur;
177 spin_unlock(&limit->p_spin);
179 if (dtsize > maxfilesperproc)
180 dtsize = maxfilesperproc;
181 if (dtsize < minfilesperproc)
182 dtsize = minfilesperproc;
183 if (p->p_ucred->cr_uid && dtsize > maxfilesperuser)
184 dtsize = maxfilesperuser;
185 uap->sysmsg_result = dtsize;
190 * Duplicate a file descriptor to a particular value.
192 * note: keep in mind that a potential race condition exists when closing
193 * descriptors from a shared descriptor table (via rfork).
198 sys_dup2(struct dup2_args *uap)
203 error = kern_dup(DUP_FIXED, uap->from, uap->to, &fd);
204 uap->sysmsg_fds[0] = fd;
210 * Duplicate a file descriptor.
215 sys_dup(struct dup_args *uap)
220 error = kern_dup(DUP_VARIABLE, uap->fd, 0, &fd);
221 uap->sysmsg_fds[0] = fd;
227 * MPALMOSTSAFE - acquires mplock for fp operations
230 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred)
232 struct thread *td = curthread;
233 struct proc *p = td->td_proc;
239 int tmp, error, flg = F_POSIX;
244 * Operations on file descriptors that do not require a file pointer.
248 error = fgetfdflags(p->p_fd, fd, &tmp);
250 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0;
254 if (dat->fc_cloexec & FD_CLOEXEC)
255 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE);
257 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE);
261 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd);
268 * Operations on file pointers
270 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
276 dat->fc_flags = OFLAGS(fp->f_flag);
282 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS;
283 nflags |= oflags & ~FCNTLFLAGS;
286 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY))
288 if (error == 0 && ((nflags ^ oflags) & FASYNC)) {
289 tmp = nflags & FASYNC;
290 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp,
298 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner,
303 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner,
309 /* Fall into F_SETLK */
312 if (fp->f_type != DTYPE_VNODE) {
316 vp = (struct vnode *)fp->f_data;
319 * copyin/lockop may block
321 if (dat->fc_flock.l_whence == SEEK_CUR)
322 dat->fc_flock.l_start += fp->f_offset;
324 switch (dat->fc_flock.l_type) {
326 if ((fp->f_flag & FREAD) == 0) {
330 p->p_leader->p_flag |= P_ADVLOCK;
331 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
332 &dat->fc_flock, flg);
335 if ((fp->f_flag & FWRITE) == 0) {
339 p->p_leader->p_flag |= P_ADVLOCK;
340 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
341 &dat->fc_flock, flg);
344 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
345 &dat->fc_flock, F_POSIX);
353 * It is possible to race a close() on the descriptor while
354 * we were blocked getting the lock. If this occurs the
355 * close might not have caught the lock.
357 if (checkfdclosed(p->p_fd, fd, fp)) {
358 dat->fc_flock.l_whence = SEEK_SET;
359 dat->fc_flock.l_start = 0;
360 dat->fc_flock.l_len = 0;
361 dat->fc_flock.l_type = F_UNLCK;
362 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
363 F_UNLCK, &dat->fc_flock, F_POSIX);
368 if (fp->f_type != DTYPE_VNODE) {
372 vp = (struct vnode *)fp->f_data;
374 * copyin/lockop may block
376 if (dat->fc_flock.l_type != F_RDLCK &&
377 dat->fc_flock.l_type != F_WRLCK &&
378 dat->fc_flock.l_type != F_UNLCK) {
382 if (dat->fc_flock.l_whence == SEEK_CUR)
383 dat->fc_flock.l_start += fp->f_offset;
384 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK,
385 &dat->fc_flock, F_POSIX);
398 * The file control system call.
403 sys_fcntl(struct fcntl_args *uap)
410 dat.fc_fd = uap->arg;
413 dat.fc_cloexec = uap->arg;
416 dat.fc_flags = uap->arg;
419 dat.fc_owner = uap->arg;
424 error = copyin((caddr_t)uap->arg, &dat.fc_flock,
425 sizeof(struct flock));
431 error = kern_fcntl(uap->fd, uap->cmd, &dat, curthread->td_ucred);
436 uap->sysmsg_result = dat.fc_fd;
439 uap->sysmsg_result = dat.fc_cloexec;
442 uap->sysmsg_result = dat.fc_flags;
445 uap->sysmsg_result = dat.fc_owner;
447 error = copyout(&dat.fc_flock, (caddr_t)uap->arg,
448 sizeof(struct flock));
457 * Common code for dup, dup2, and fcntl(F_DUPFD).
459 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells
460 * kern_dup() to destructively dup over an existing file descriptor if new
461 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest
462 * unused file descriptor that is greater than or equal to new.
467 kern_dup(enum dup_type type, int old, int new, int *res)
469 struct thread *td = curthread;
470 struct proc *p = td->td_proc;
471 struct filedesc *fdp = p->p_fd;
480 * Verify that we have a valid descriptor to dup from and
481 * possibly to dup to.
483 * NOTE: maxfilesperuser is not applicable to dup()
486 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
489 dtsize = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
490 if (dtsize > maxfilesperproc)
491 dtsize = maxfilesperproc;
492 if (dtsize < minfilesperproc)
493 dtsize = minfilesperproc;
495 if (new < 0 || new > dtsize)
498 spin_lock(&fdp->fd_spin);
499 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) {
500 spin_unlock(&fdp->fd_spin);
503 if (type == DUP_FIXED && old == new) {
505 spin_unlock(&fdp->fd_spin);
508 fp = fdp->fd_files[old].fp;
509 oldflags = fdp->fd_files[old].fileflags;
510 fhold(fp); /* MPSAFE - can be called with a spinlock held */
513 * Allocate a new descriptor if DUP_VARIABLE, or expand the table
514 * if the requested descriptor is beyond the current table size.
516 * This can block. Retry if the source descriptor no longer matches
517 * or if our expectation in the expansion case races.
519 * If we are not expanding or allocating a new decriptor, then reset
520 * the target descriptor to a reserved state so we have a uniform
521 * setup for the next code block.
523 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) {
524 spin_unlock(&fdp->fd_spin);
525 error = fdalloc(p, new, &newfd);
526 spin_lock(&fdp->fd_spin);
528 spin_unlock(&fdp->fd_spin);
535 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) {
536 fsetfd_locked(fdp, NULL, newfd);
537 spin_unlock(&fdp->fd_spin);
542 * Check for expansion race
544 if (type != DUP_VARIABLE && new != newfd) {
545 fsetfd_locked(fdp, NULL, newfd);
546 spin_unlock(&fdp->fd_spin);
551 * Check for ripout, newfd reused old (this case probably
555 fsetfd_locked(fdp, NULL, newfd);
556 spin_unlock(&fdp->fd_spin);
563 if (fdp->fd_files[new].reserved) {
564 spin_unlock(&fdp->fd_spin);
566 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new);
567 tsleep(fdp, 0, "fdres", hz);
572 * If the target descriptor was never allocated we have
573 * to allocate it. If it was we have to clean out the
574 * old descriptor. delfp inherits the ref from the
577 delfp = fdp->fd_files[new].fp;
578 fdp->fd_files[new].fp = NULL;
579 fdp->fd_files[new].reserved = 1;
581 fdreserve_locked(fdp, new, 1);
582 if (new > fdp->fd_lastfile)
583 fdp->fd_lastfile = new;
589 * NOTE: still holding an exclusive spinlock
593 * If a descriptor is being overwritten we may hve to tell
594 * fdfree() to sleep to ensure that all relevant process
595 * leaders can be traversed in closef().
597 if (delfp != NULL && p->p_fdtol != NULL) {
598 fdp->fd_holdleaderscount++;
603 KASSERT(delfp == NULL || type == DUP_FIXED,
604 ("dup() picked an open file"));
607 * Duplicate the source descriptor, update lastfile. If the new
608 * descriptor was not allocated and we aren't replacing an existing
609 * descriptor we have to mark the descriptor as being in use.
611 * The fd_files[] array inherits fp's hold reference.
613 fsetfd_locked(fdp, fp, new);
614 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE;
615 spin_unlock(&fdp->fd_spin);
620 * If we dup'd over a valid file, we now own the reference to it
621 * and must dispose of it using closef() semantics (as if a
622 * close() were performed on it).
625 if (SLIST_FIRST(&delfp->f_klist))
626 knote_fdclose(delfp, fdp, new);
629 spin_lock(&fdp->fd_spin);
630 fdp->fd_holdleaderscount--;
631 if (fdp->fd_holdleaderscount == 0 &&
632 fdp->fd_holdleaderswakeup != 0) {
633 fdp->fd_holdleaderswakeup = 0;
634 spin_unlock(&fdp->fd_spin);
635 wakeup(&fdp->fd_holdleaderscount);
637 spin_unlock(&fdp->fd_spin);
645 * If sigio is on the list associated with a process or process group,
646 * disable signalling from the device, remove sigio from the list and
650 funsetown(struct sigio *sigio)
655 *(sigio->sio_myref) = NULL;
657 if (sigio->sio_pgid < 0) {
658 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
660 } else /* if ((*sigiop)->sio_pgid > 0) */ {
661 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
664 crfree(sigio->sio_ucred);
665 kfree(sigio, M_SIGIO);
668 /* Free a list of sigio structures. */
670 funsetownlst(struct sigiolst *sigiolst)
674 while ((sigio = SLIST_FIRST(sigiolst)) != NULL)
679 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
681 * After permission checking, add a sigio structure to the sigio list for
682 * the process or process group.
685 fsetown(pid_t pgid, struct sigio **sigiop)
701 * Policy - Don't allow a process to FSETOWN a process
702 * in another session.
704 * Remove this test to allow maximum flexibility or
705 * restrict FSETOWN to the current process or process
706 * group for maximum safety.
708 if (proc->p_session != curproc->p_session)
712 } else /* if (pgid < 0) */ {
713 pgrp = pgfind(-pgid);
718 * Policy - Don't allow a process to FSETOWN a process
719 * in another session.
721 * Remove this test to allow maximum flexibility or
722 * restrict FSETOWN to the current process or process
723 * group for maximum safety.
725 if (pgrp->pg_session != curproc->p_session)
731 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK);
733 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
734 sigio->sio_proc = proc;
736 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
737 sigio->sio_pgrp = pgrp;
739 sigio->sio_pgid = pgid;
740 sigio->sio_ucred = crhold(curthread->td_ucred);
741 /* It would be convenient if p_ruid was in ucred. */
742 sigio->sio_ruid = sigio->sio_ucred->cr_ruid;
743 sigio->sio_myref = sigiop;
751 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
754 fgetown(struct sigio *sigio)
756 return (sigio != NULL ? sigio->sio_pgid : 0);
760 * Close many file descriptors.
765 sys_closefrom(struct closefrom_args *uap)
767 return(kern_closefrom(uap->fd));
771 * Close all file descriptors greater then or equal to fd
776 kern_closefrom(int fd)
778 struct thread *td = curthread;
779 struct proc *p = td->td_proc;
780 struct filedesc *fdp;
789 * NOTE: This function will skip unassociated descriptors and
790 * reserved descriptors that have not yet been assigned.
791 * fd_lastfile can change as a side effect of kern_close().
793 spin_lock(&fdp->fd_spin);
794 while (fd <= fdp->fd_lastfile) {
795 if (fdp->fd_files[fd].fp != NULL) {
796 spin_unlock(&fdp->fd_spin);
797 /* ok if this races another close */
798 if (kern_close(fd) == EINTR)
800 spin_lock(&fdp->fd_spin);
804 spin_unlock(&fdp->fd_spin);
809 * Close a file descriptor.
814 sys_close(struct close_args *uap)
816 return(kern_close(uap->fd));
820 * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls
825 struct thread *td = curthread;
826 struct proc *p = td->td_proc;
827 struct filedesc *fdp;
835 spin_lock(&fdp->fd_spin);
836 if ((fp = funsetfd_locked(fdp, fd)) == NULL) {
837 spin_unlock(&fdp->fd_spin);
841 if (p->p_fdtol != NULL) {
843 * Ask fdfree() to sleep to ensure that all relevant
844 * process leaders can be traversed in closef().
846 fdp->fd_holdleaderscount++;
851 * we now hold the fp reference that used to be owned by the descriptor
854 spin_unlock(&fdp->fd_spin);
855 if (SLIST_FIRST(&fp->f_klist))
856 knote_fdclose(fp, fdp, fd);
857 error = closef(fp, p);
859 spin_lock(&fdp->fd_spin);
860 fdp->fd_holdleaderscount--;
861 if (fdp->fd_holdleaderscount == 0 &&
862 fdp->fd_holdleaderswakeup != 0) {
863 fdp->fd_holdleaderswakeup = 0;
864 spin_unlock(&fdp->fd_spin);
865 wakeup(&fdp->fd_holdleaderscount);
867 spin_unlock(&fdp->fd_spin);
874 * shutdown_args(int fd, int how)
877 kern_shutdown(int fd, int how)
879 struct thread *td = curthread;
880 struct proc *p = td->td_proc;
886 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
888 error = fo_shutdown(fp, how);
898 sys_shutdown(struct shutdown_args *uap)
903 error = kern_shutdown(uap->s, uap->how);
913 kern_fstat(int fd, struct stat *ub)
915 struct thread *td = curthread;
916 struct proc *p = td->td_proc;
922 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
924 error = fo_stat(fp, ub, td->td_ucred);
931 * Return status information about a file descriptor.
936 sys_fstat(struct fstat_args *uap)
941 error = kern_fstat(uap->fd, &st);
944 error = copyout(&st, uap->sb, sizeof(st));
949 * Return pathconf information about a file descriptor.
954 sys_fpathconf(struct fpathconf_args *uap)
956 struct thread *td = curthread;
957 struct proc *p = td->td_proc;
962 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
965 switch (fp->f_type) {
968 if (uap->name != _PC_PIPE_BUF) {
971 uap->sysmsg_result = PIPE_BUF;
977 vp = (struct vnode *)fp->f_data;
979 error = VOP_PATHCONF(vp, uap->name, &uap->sysmsg_reg);
991 SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand,
995 * Grow the file table so it can hold through descriptor (want).
997 * The fdp's spinlock must be held exclusively on entry and may be held
998 * exclusively on return. The spinlock may be cycled by the routine.
1003 fdgrow_locked(struct filedesc *fdp, int want)
1005 struct fdnode *newfiles;
1006 struct fdnode *oldfiles;
1009 nf = fdp->fd_nfiles;
1011 /* nf has to be of the form 2^n - 1 */
1013 } while (nf <= want);
1015 spin_unlock(&fdp->fd_spin);
1016 newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK);
1017 spin_lock(&fdp->fd_spin);
1020 * We could have raced another extend while we were not holding
1023 if (fdp->fd_nfiles >= nf) {
1024 spin_unlock(&fdp->fd_spin);
1025 kfree(newfiles, M_FILEDESC);
1026 spin_lock(&fdp->fd_spin);
1030 * Copy the existing ofile and ofileflags arrays
1031 * and zero the new portion of each array.
1033 extra = nf - fdp->fd_nfiles;
1034 bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode));
1035 bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode));
1037 oldfiles = fdp->fd_files;
1038 fdp->fd_files = newfiles;
1039 fdp->fd_nfiles = nf;
1041 if (oldfiles != fdp->fd_builtin_files) {
1042 spin_unlock(&fdp->fd_spin);
1043 kfree(oldfiles, M_FILEDESC);
1044 spin_lock(&fdp->fd_spin);
1050 * Number of nodes in right subtree, including the root.
1053 right_subtree_size(int n)
1055 return (n ^ (n | (n + 1)));
1062 right_ancestor(int n)
1064 return (n | (n + 1));
1071 left_ancestor(int n)
1073 return ((n & (n + 1)) - 1);
1077 * Traverse the in-place binary tree buttom-up adjusting the allocation
1078 * count so scans can determine where free descriptors are located.
1080 * MPSAFE - caller must be holding an exclusive spinlock on fdp
1084 fdreserve_locked(struct filedesc *fdp, int fd, int incr)
1087 fdp->fd_files[fd].allocated += incr;
1088 KKASSERT(fdp->fd_files[fd].allocated >= 0);
1089 fd = left_ancestor(fd);
1094 * Reserve a file descriptor for the process. If no error occurs, the
1095 * caller MUST at some point call fsetfd() or assign a file pointer
1096 * or dispose of the reservation.
1101 fdalloc(struct proc *p, int want, int *result)
1103 struct filedesc *fdp = p->p_fd;
1104 struct uidinfo *uip;
1105 int fd, rsize, rsum, node, lim;
1108 * Check dtable size limit
1110 spin_lock(&p->p_limit->p_spin);
1111 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
1114 lim = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
1115 spin_unlock(&p->p_limit->p_spin);
1117 if (lim > maxfilesperproc)
1118 lim = maxfilesperproc;
1119 if (lim < minfilesperproc)
1120 lim = minfilesperproc;
1125 * Check that the user has not run out of descriptors (non-root only).
1126 * As a safety measure the dtable is allowed to have at least
1127 * minfilesperproc open fds regardless of the maxfilesperuser limit.
1129 if (p->p_ucred->cr_uid && fdp->fd_nfiles >= minfilesperproc) {
1130 uip = p->p_ucred->cr_uidinfo;
1131 if (uip->ui_openfiles > maxfilesperuser) {
1132 krateprintf(&krate_uidinfo,
1133 "Warning: user %d pid %d (%s) ran out of "
1134 "file descriptors (%d/%d)\n",
1135 p->p_ucred->cr_uid, (int)p->p_pid,
1137 uip->ui_openfiles, maxfilesperuser);
1143 * Grow the dtable if necessary
1145 spin_lock(&fdp->fd_spin);
1146 if (want >= fdp->fd_nfiles)
1147 fdgrow_locked(fdp, want);
1150 * Search for a free descriptor starting at the higher
1151 * of want or fd_freefile. If that fails, consider
1152 * expanding the ofile array.
1154 * NOTE! the 'allocated' field is a cumulative recursive allocation
1155 * count. If we happen to see a value of 0 then we can shortcut
1156 * our search. Otherwise we run through through the tree going
1157 * down branches we know have free descriptor(s) until we hit a
1158 * leaf node. The leaf node will be free but will not necessarily
1159 * have an allocated field of 0.
1162 /* move up the tree looking for a subtree with a free node */
1163 for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim);
1164 fd = right_ancestor(fd)) {
1165 if (fdp->fd_files[fd].allocated == 0)
1168 rsize = right_subtree_size(fd);
1169 if (fdp->fd_files[fd].allocated == rsize)
1170 continue; /* right subtree full */
1173 * Free fd is in the right subtree of the tree rooted at fd.
1174 * Call that subtree R. Look for the smallest (leftmost)
1175 * subtree of R with an unallocated fd: continue moving
1176 * down the left branch until encountering a full left
1177 * subtree, then move to the right.
1179 for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) {
1181 rsum += fdp->fd_files[node].allocated;
1182 if (fdp->fd_files[fd].allocated == rsum + rsize) {
1183 fd = node; /* move to the right */
1184 if (fdp->fd_files[node].allocated == 0)
1193 * No space in current array. Expand?
1195 if (fdp->fd_nfiles >= lim) {
1196 spin_unlock(&fdp->fd_spin);
1199 fdgrow_locked(fdp, want);
1203 KKASSERT(fd < fdp->fd_nfiles);
1204 if (fd > fdp->fd_lastfile)
1205 fdp->fd_lastfile = fd;
1206 if (want <= fdp->fd_freefile)
1207 fdp->fd_freefile = fd;
1209 KKASSERT(fdp->fd_files[fd].fp == NULL);
1210 KKASSERT(fdp->fd_files[fd].reserved == 0);
1211 fdp->fd_files[fd].fileflags = 0;
1212 fdp->fd_files[fd].reserved = 1;
1213 fdreserve_locked(fdp, fd, 1);
1214 spin_unlock(&fdp->fd_spin);
1219 * Check to see whether n user file descriptors
1220 * are available to the process p.
1225 fdavail(struct proc *p, int n)
1227 struct filedesc *fdp = p->p_fd;
1228 struct fdnode *fdnode;
1231 spin_lock(&p->p_limit->p_spin);
1232 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
1235 lim = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
1236 spin_unlock(&p->p_limit->p_spin);
1238 if (lim > maxfilesperproc)
1239 lim = maxfilesperproc;
1240 if (lim < minfilesperproc)
1241 lim = minfilesperproc;
1243 spin_lock(&fdp->fd_spin);
1244 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) {
1245 spin_unlock(&fdp->fd_spin);
1248 last = min(fdp->fd_nfiles, lim);
1249 fdnode = &fdp->fd_files[fdp->fd_freefile];
1250 for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) {
1251 if (fdnode->fp == NULL && --n <= 0) {
1252 spin_unlock(&fdp->fd_spin);
1256 spin_unlock(&fdp->fd_spin);
1261 * Revoke open descriptors referencing (f_data, f_type)
1263 * Any revoke executed within a prison is only able to
1264 * revoke descriptors for processes within that prison.
1266 * Returns 0 on success or an error code.
1268 struct fdrevoke_info {
1278 static int fdrevoke_check_callback(struct file *fp, void *vinfo);
1279 static int fdrevoke_proc_callback(struct proc *p, void *vinfo);
1282 fdrevoke(void *f_data, short f_type, struct ucred *cred)
1284 struct fdrevoke_info info;
1287 bzero(&info, sizeof(info));
1291 error = falloc(NULL, &info.nfp, NULL);
1296 * Scan the file pointer table once. dups do not dup file pointers,
1297 * only descriptors, so there is no leak. Set FREVOKED on the fps
1300 allfiles_scan_exclusive(fdrevoke_check_callback, &info);
1303 * If any fps were marked track down the related descriptors
1304 * and close them. Any dup()s at this point will notice
1305 * the FREVOKED already set in the fp and do the right thing.
1307 * Any fps with non-zero msgcounts (aka sent over a unix-domain
1308 * socket) bumped the intransit counter and will require a
1309 * scan. Races against fps leaving the socket are closed by
1310 * the socket code checking for FREVOKED.
1313 allproc_scan(fdrevoke_proc_callback, &info);
1315 unp_revoke_gc(info.nfp);
1321 * Locate matching file pointers directly.
1324 fdrevoke_check_callback(struct file *fp, void *vinfo)
1326 struct fdrevoke_info *info = vinfo;
1329 * File pointers already flagged for revokation are skipped.
1331 if (fp->f_flag & FREVOKED)
1335 * If revoking from a prison file pointers created outside of
1336 * that prison, or file pointers without creds, cannot be revoked.
1338 if (info->cred->cr_prison &&
1339 (fp->f_cred == NULL ||
1340 info->cred->cr_prison != fp->f_cred->cr_prison)) {
1345 * If the file pointer matches then mark it for revocation. The
1346 * flag is currently only used by unp_revoke_gc().
1348 * info->count is a heuristic and can race in a SMP environment.
1350 if (info->data == fp->f_data && info->type == fp->f_type) {
1351 atomic_set_int(&fp->f_flag, FREVOKED);
1352 info->count += fp->f_count;
1360 * Locate matching file pointers via process descriptor tables.
1363 fdrevoke_proc_callback(struct proc *p, void *vinfo)
1365 struct fdrevoke_info *info = vinfo;
1366 struct filedesc *fdp;
1370 if (p->p_stat == SIDL || p->p_stat == SZOMB)
1372 if (info->cred->cr_prison &&
1373 info->cred->cr_prison != p->p_ucred->cr_prison) {
1378 * If the controlling terminal of the process matches the
1379 * vnode being revoked we clear the controlling terminal.
1381 * The normal spec_close() may not catch this because it
1382 * uses curproc instead of p.
1384 if (p->p_session && info->type == DTYPE_VNODE &&
1385 info->data == p->p_session->s_ttyvp) {
1386 p->p_session->s_ttyvp = NULL;
1391 * Softref the fdp to prevent it from being destroyed
1393 spin_lock(&p->p_spin);
1394 if ((fdp = p->p_fd) == NULL) {
1395 spin_unlock(&p->p_spin);
1398 atomic_add_int(&fdp->fd_softrefs, 1);
1399 spin_unlock(&p->p_spin);
1402 * Locate and close any matching file descriptors.
1404 spin_lock(&fdp->fd_spin);
1405 for (n = 0; n < fdp->fd_nfiles; ++n) {
1406 if ((fp = fdp->fd_files[n].fp) == NULL)
1408 if (fp->f_flag & FREVOKED) {
1410 fdp->fd_files[n].fp = info->nfp;
1411 spin_unlock(&fdp->fd_spin);
1412 knote_fdclose(fp, fdp, n); /* XXX */
1414 spin_lock(&fdp->fd_spin);
1418 spin_unlock(&fdp->fd_spin);
1419 atomic_subtract_int(&fdp->fd_softrefs, 1);
1425 * Create a new open file structure and reserve a file decriptor
1426 * for the process that refers to it.
1428 * Root creds are checked using lp, or assumed if lp is NULL. If
1429 * resultfd is non-NULL then lp must also be non-NULL. No file
1430 * descriptor is reserved (and no process context is needed) if
1433 * A file pointer with a refcount of 1 is returned. Note that the
1434 * file pointer is NOT associated with the descriptor. If falloc
1435 * returns success, fsetfd() MUST be called to either associate the
1436 * file pointer or clear the reservation.
1441 falloc(struct lwp *lp, struct file **resultfp, int *resultfd)
1443 static struct timeval lastfail;
1446 struct ucred *cred = lp ? lp->lwp_thread->td_ucred : proc0.p_ucred;
1452 * Handle filetable full issues and root overfill.
1454 if (nfiles >= maxfiles - maxfilesrootres &&
1455 (cred->cr_ruid != 0 || nfiles >= maxfiles)) {
1456 if (ppsratecheck(&lastfail, &curfail, 1)) {
1457 kprintf("kern.maxfiles limit exceeded by uid %d, "
1458 "please see tuning(7).\n",
1466 * Allocate a new file descriptor.
1468 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO);
1469 spin_init(&fp->f_spin);
1470 SLIST_INIT(&fp->f_klist);
1472 fp->f_ops = &badfileops;
1475 spin_lock(&filehead_spin);
1477 LIST_INSERT_HEAD(&filehead, fp, f_list);
1478 spin_unlock(&filehead_spin);
1480 if ((error = fdalloc(lp->lwp_proc, 0, resultfd)) != 0) {
1493 * Check for races against a file descriptor by determining that the
1494 * file pointer is still associated with the specified file descriptor,
1495 * and a close is not currently in progress.
1500 checkfdclosed(struct filedesc *fdp, int fd, struct file *fp)
1504 spin_lock(&fdp->fd_spin);
1505 if ((unsigned)fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp)
1509 spin_unlock(&fdp->fd_spin);
1514 * Associate a file pointer with a previously reserved file descriptor.
1515 * This function always succeeds.
1517 * If fp is NULL, the file descriptor is returned to the pool.
1521 * MPSAFE (exclusive spinlock must be held on call)
1524 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd)
1526 KKASSERT((unsigned)fd < fdp->fd_nfiles);
1527 KKASSERT(fdp->fd_files[fd].reserved != 0);
1530 fdp->fd_files[fd].fp = fp;
1531 fdp->fd_files[fd].reserved = 0;
1533 fdp->fd_files[fd].reserved = 0;
1534 fdreserve_locked(fdp, fd, -1);
1535 fdfixup_locked(fdp, fd);
1543 fsetfd(struct filedesc *fdp, struct file *fp, int fd)
1545 spin_lock(&fdp->fd_spin);
1546 fsetfd_locked(fdp, fp, fd);
1547 spin_unlock(&fdp->fd_spin);
1551 * MPSAFE (exclusive spinlock must be held on call)
1555 funsetfd_locked(struct filedesc *fdp, int fd)
1559 if ((unsigned)fd >= fdp->fd_nfiles)
1561 if ((fp = fdp->fd_files[fd].fp) == NULL)
1563 fdp->fd_files[fd].fp = NULL;
1564 fdp->fd_files[fd].fileflags = 0;
1566 fdreserve_locked(fdp, fd, -1);
1567 fdfixup_locked(fdp, fd);
1575 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp)
1579 spin_lock(&fdp->fd_spin);
1580 if (((u_int)fd) >= fdp->fd_nfiles) {
1582 } else if (fdp->fd_files[fd].fp == NULL) {
1585 *flagsp = fdp->fd_files[fd].fileflags;
1588 spin_unlock(&fdp->fd_spin);
1596 fsetfdflags(struct filedesc *fdp, int fd, int add_flags)
1600 spin_lock(&fdp->fd_spin);
1601 if (((u_int)fd) >= fdp->fd_nfiles) {
1603 } else if (fdp->fd_files[fd].fp == NULL) {
1606 fdp->fd_files[fd].fileflags |= add_flags;
1609 spin_unlock(&fdp->fd_spin);
1617 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags)
1621 spin_lock(&fdp->fd_spin);
1622 if (((u_int)fd) >= fdp->fd_nfiles) {
1624 } else if (fdp->fd_files[fd].fp == NULL) {
1627 fdp->fd_files[fd].fileflags &= ~rem_flags;
1630 spin_unlock(&fdp->fd_spin);
1635 * Set/Change/Clear the creds for a fp and synchronize the uidinfo.
1638 fsetcred(struct file *fp, struct ucred *ncr)
1641 struct uidinfo *uip;
1644 if (ocr == NULL || ncr == NULL || ocr->cr_uidinfo != ncr->cr_uidinfo) {
1646 uip = ocr->cr_uidinfo;
1647 atomic_add_int(&uip->ui_openfiles, -1);
1650 uip = ncr->cr_uidinfo;
1651 atomic_add_int(&uip->ui_openfiles, 1);
1662 * Free a file descriptor.
1666 ffree(struct file *fp)
1668 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!"));
1669 spin_lock(&filehead_spin);
1670 LIST_REMOVE(fp, f_list);
1672 spin_unlock(&filehead_spin);
1674 if (fp->f_nchandle.ncp)
1675 cache_drop(&fp->f_nchandle);
1680 * called from init_main, initialize filedesc0 for proc0.
1683 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask)
1687 fdp0->fd_refcnt = 1;
1688 fdp0->fd_cmask = cmask;
1689 fdp0->fd_files = fdp0->fd_builtin_files;
1690 fdp0->fd_nfiles = NDFILE;
1691 fdp0->fd_lastfile = -1;
1692 spin_init(&fdp0->fd_spin);
1696 * Build a new filedesc structure.
1701 fdinit(struct proc *p)
1703 struct filedesc *newfdp;
1704 struct filedesc *fdp = p->p_fd;
1706 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO);
1707 spin_lock(&fdp->fd_spin);
1709 newfdp->fd_cdir = fdp->fd_cdir;
1710 vref(newfdp->fd_cdir);
1711 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1715 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of
1716 * proc0, but should unconditionally exist in other processes.
1719 newfdp->fd_rdir = fdp->fd_rdir;
1720 vref(newfdp->fd_rdir);
1721 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1724 newfdp->fd_jdir = fdp->fd_jdir;
1725 vref(newfdp->fd_jdir);
1726 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1728 spin_unlock(&fdp->fd_spin);
1730 /* Create the file descriptor table. */
1731 newfdp->fd_refcnt = 1;
1732 newfdp->fd_cmask = cmask;
1733 newfdp->fd_files = newfdp->fd_builtin_files;
1734 newfdp->fd_nfiles = NDFILE;
1735 newfdp->fd_lastfile = -1;
1736 spin_init(&newfdp->fd_spin);
1742 * Share a filedesc structure.
1747 fdshare(struct proc *p)
1749 struct filedesc *fdp;
1752 spin_lock(&fdp->fd_spin);
1754 spin_unlock(&fdp->fd_spin);
1759 * Copy a filedesc structure.
1764 fdcopy(struct proc *p)
1766 struct filedesc *fdp = p->p_fd;
1767 struct filedesc *newfdp;
1768 struct fdnode *fdnode;
1773 * Certain daemons might not have file descriptors.
1779 * Allocate the new filedesc and fd_files[] array. This can race
1780 * with operations by other threads on the fdp so we have to be
1783 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO);
1785 spin_lock(&fdp->fd_spin);
1786 if (fdp->fd_lastfile < NDFILE) {
1787 newfdp->fd_files = newfdp->fd_builtin_files;
1791 * We have to allocate (N^2-1) entries for our in-place
1792 * binary tree. Allow the table to shrink.
1796 while (ni > fdp->fd_lastfile && ni > NDFILE) {
1800 spin_unlock(&fdp->fd_spin);
1801 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode),
1802 M_FILEDESC, M_WAITOK | M_ZERO);
1805 * Check for race, retry
1807 spin_lock(&fdp->fd_spin);
1808 if (i <= fdp->fd_lastfile) {
1809 spin_unlock(&fdp->fd_spin);
1810 kfree(newfdp->fd_files, M_FILEDESC);
1816 * Dup the remaining fields. vref() and cache_hold() can be
1817 * safely called while holding the read spinlock on fdp.
1819 * The read spinlock on fdp is still being held.
1821 * NOTE: vref and cache_hold calls for the case where the vnode
1822 * or cache entry already has at least one ref may be called
1823 * while holding spin locks.
1825 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) {
1826 vref(newfdp->fd_cdir);
1827 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1830 * We must check for fd_rdir here, at least for now because
1831 * the init process is created before we have access to the
1832 * rootvode to take a reference to it.
1834 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) {
1835 vref(newfdp->fd_rdir);
1836 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1838 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) {
1839 vref(newfdp->fd_jdir);
1840 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1842 newfdp->fd_refcnt = 1;
1843 newfdp->fd_nfiles = i;
1844 newfdp->fd_lastfile = fdp->fd_lastfile;
1845 newfdp->fd_freefile = fdp->fd_freefile;
1846 newfdp->fd_cmask = fdp->fd_cmask;
1847 spin_init(&newfdp->fd_spin);
1850 * Copy the descriptor table through (i). This also copies the
1851 * allocation state. Then go through and ref the file pointers
1852 * and clean up any KQ descriptors.
1854 * kq descriptors cannot be copied. Since we haven't ref'd the
1855 * copied files yet we can ignore the return value from funsetfd().
1857 * The read spinlock on fdp is still being held.
1859 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode));
1860 for (i = 0 ; i < newfdp->fd_nfiles; ++i) {
1861 fdnode = &newfdp->fd_files[i];
1862 if (fdnode->reserved) {
1863 fdreserve_locked(newfdp, i, -1);
1864 fdnode->reserved = 0;
1865 fdfixup_locked(newfdp, i);
1866 } else if (fdnode->fp) {
1867 if (fdnode->fp->f_type == DTYPE_KQUEUE) {
1868 (void)funsetfd_locked(newfdp, i);
1874 spin_unlock(&fdp->fd_spin);
1879 * Release a filedesc structure.
1881 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE)
1884 fdfree(struct proc *p, struct filedesc *repl)
1886 struct filedesc *fdp;
1887 struct fdnode *fdnode;
1889 struct filedesc_to_leader *fdtol;
1895 * Certain daemons might not have file descriptors.
1904 * Severe messing around to follow.
1906 spin_lock(&fdp->fd_spin);
1908 /* Check for special need to clear POSIX style locks */
1910 if (fdtol != NULL) {
1911 KASSERT(fdtol->fdl_refcount > 0,
1912 ("filedesc_to_refcount botch: fdl_refcount=%d",
1913 fdtol->fdl_refcount));
1914 if (fdtol->fdl_refcount == 1 &&
1915 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1916 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1917 fdnode = &fdp->fd_files[i];
1918 if (fdnode->fp == NULL ||
1919 fdnode->fp->f_type != DTYPE_VNODE) {
1924 spin_unlock(&fdp->fd_spin);
1926 lf.l_whence = SEEK_SET;
1929 lf.l_type = F_UNLCK;
1930 vp = (struct vnode *)fp->f_data;
1931 (void) VOP_ADVLOCK(vp,
1932 (caddr_t)p->p_leader,
1937 spin_lock(&fdp->fd_spin);
1941 if (fdtol->fdl_refcount == 1) {
1942 if (fdp->fd_holdleaderscount > 0 &&
1943 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1945 * close() or do_dup() has cleared a reference
1946 * in a shared file descriptor table.
1948 fdp->fd_holdleaderswakeup = 1;
1949 ssleep(&fdp->fd_holdleaderscount,
1950 &fdp->fd_spin, 0, "fdlhold", 0);
1953 if (fdtol->fdl_holdcount > 0) {
1955 * Ensure that fdtol->fdl_leader
1956 * remains valid in closef().
1958 fdtol->fdl_wakeup = 1;
1959 ssleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0);
1963 fdtol->fdl_refcount--;
1964 if (fdtol->fdl_refcount == 0 &&
1965 fdtol->fdl_holdcount == 0) {
1966 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
1967 fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
1972 if (fdtol != NULL) {
1973 spin_unlock(&fdp->fd_spin);
1974 kfree(fdtol, M_FILEDESC_TO_LEADER);
1975 spin_lock(&fdp->fd_spin);
1978 if (--fdp->fd_refcnt > 0) {
1979 spin_unlock(&fdp->fd_spin);
1980 spin_lock(&p->p_spin);
1982 spin_unlock(&p->p_spin);
1987 * Even though we are the last reference to the structure allproc
1988 * scans may still reference the structure. Maintain proper
1989 * locks until we can replace p->p_fd.
1991 * Also note that kqueue's closef still needs to reference the
1992 * fdp via p->p_fd, so we have to close the descriptors before
1993 * we replace p->p_fd.
1995 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1996 if (fdp->fd_files[i].fp) {
1997 fp = funsetfd_locked(fdp, i);
1999 spin_unlock(&fdp->fd_spin);
2000 if (SLIST_FIRST(&fp->f_klist))
2001 knote_fdclose(fp, fdp, i);
2003 spin_lock(&fdp->fd_spin);
2007 spin_unlock(&fdp->fd_spin);
2010 * Interlock against an allproc scan operations (typically frevoke).
2012 spin_lock(&p->p_spin);
2014 spin_unlock(&p->p_spin);
2017 * Wait for any softrefs to go away. This race rarely occurs so
2018 * we can use a non-critical-path style poll/sleep loop. The
2019 * race only occurs against allproc scans.
2021 * No new softrefs can occur with the fdp disconnected from the
2024 if (fdp->fd_softrefs) {
2025 kprintf("pid %d: Warning, fdp race avoided\n", p->p_pid);
2026 while (fdp->fd_softrefs)
2027 tsleep(&fdp->fd_softrefs, 0, "fdsoft", 1);
2030 if (fdp->fd_files != fdp->fd_builtin_files)
2031 kfree(fdp->fd_files, M_FILEDESC);
2033 cache_drop(&fdp->fd_ncdir);
2034 vrele(fdp->fd_cdir);
2037 cache_drop(&fdp->fd_nrdir);
2038 vrele(fdp->fd_rdir);
2041 cache_drop(&fdp->fd_njdir);
2042 vrele(fdp->fd_jdir);
2044 kfree(fdp, M_FILEDESC);
2048 * Retrieve and reference the file pointer associated with a descriptor.
2053 holdfp(struct filedesc *fdp, int fd, int flag)
2057 spin_lock(&fdp->fd_spin);
2058 if (((u_int)fd) >= fdp->fd_nfiles) {
2062 if ((fp = fdp->fd_files[fd].fp) == NULL)
2064 if ((fp->f_flag & flag) == 0 && flag != -1) {
2070 spin_unlock(&fdp->fd_spin);
2075 * holdsock() - load the struct file pointer associated
2076 * with a socket into *fpp. If an error occurs, non-zero
2077 * will be returned and *fpp will be set to NULL.
2082 holdsock(struct filedesc *fdp, int fd, struct file **fpp)
2087 spin_lock(&fdp->fd_spin);
2088 if ((unsigned)fd >= fdp->fd_nfiles) {
2093 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2097 if (fp->f_type != DTYPE_SOCKET) {
2104 spin_unlock(&fdp->fd_spin);
2110 * Convert a user file descriptor to a held file pointer.
2115 holdvnode(struct filedesc *fdp, int fd, struct file **fpp)
2120 spin_lock(&fdp->fd_spin);
2121 if ((unsigned)fd >= fdp->fd_nfiles) {
2126 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2130 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) {
2138 spin_unlock(&fdp->fd_spin);
2144 * For setugid programs, we don't want to people to use that setugidness
2145 * to generate error messages which write to a file which otherwise would
2146 * otherwise be off-limits to the process.
2148 * This is a gross hack to plug the hole. A better solution would involve
2149 * a special vop or other form of generalized access control mechanism. We
2150 * go ahead and just reject all procfs file systems accesses as dangerous.
2152 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is
2153 * sufficient. We also don't for check setugidness since we know we are.
2156 is_unsafe(struct file *fp)
2158 if (fp->f_type == DTYPE_VNODE &&
2159 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS)
2165 * Make this setguid thing safe, if at all possible.
2167 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2170 setugidsafety(struct proc *p)
2172 struct filedesc *fdp = p->p_fd;
2175 /* Certain daemons might not have file descriptors. */
2180 * note: fdp->fd_files may be reallocated out from under us while
2181 * we are blocked in a close. Be careful!
2183 for (i = 0; i <= fdp->fd_lastfile; i++) {
2186 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) {
2190 * NULL-out descriptor prior to close to avoid
2191 * a race while close blocks.
2193 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2194 knote_fdclose(fp, fdp, i);
2202 * Close any files on exec?
2204 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2207 fdcloseexec(struct proc *p)
2209 struct filedesc *fdp = p->p_fd;
2212 /* Certain daemons might not have file descriptors. */
2217 * We cannot cache fd_files since operations may block and rip
2218 * them out from under us.
2220 for (i = 0; i <= fdp->fd_lastfile; i++) {
2221 if (fdp->fd_files[i].fp != NULL &&
2222 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) {
2226 * NULL-out descriptor prior to close to avoid
2227 * a race while close blocks.
2229 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2230 knote_fdclose(fp, fdp, i);
2238 * It is unsafe for set[ug]id processes to be started with file
2239 * descriptors 0..2 closed, as these descriptors are given implicit
2240 * significance in the Standard C library. fdcheckstd() will create a
2241 * descriptor referencing /dev/null for each of stdin, stdout, and
2242 * stderr that is not already open.
2244 * NOT MPSAFE - calls falloc, vn_open, etc
2247 fdcheckstd(struct lwp *lp)
2249 struct nlookupdata nd;
2250 struct filedesc *fdp;
2253 int i, error, flags, devnull;
2255 fdp = lp->lwp_proc->p_fd;
2260 for (i = 0; i < 3; i++) {
2261 if (fdp->fd_files[i].fp != NULL)
2264 if ((error = falloc(lp, &fp, &devnull)) != 0)
2267 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE,
2268 NLC_FOLLOW|NLC_LOCKVP);
2269 flags = FREAD | FWRITE;
2271 error = vn_open(&nd, fp, flags, 0);
2273 fsetfd(fdp, fp, devnull);
2275 fsetfd(fdp, NULL, devnull);
2280 KKASSERT(i == devnull);
2282 error = kern_dup(DUP_FIXED, devnull, i, &retval);
2291 * Internal form of close.
2292 * Decrement reference count on file structure.
2293 * Note: td and/or p may be NULL when closing a file
2294 * that was being passed in a message.
2296 * MPALMOSTSAFE - acquires mplock for VOP operations
2299 closef(struct file *fp, struct proc *p)
2303 struct filedesc_to_leader *fdtol;
2309 * POSIX record locking dictates that any close releases ALL
2310 * locks owned by this process. This is handled by setting
2311 * a flag in the unlock to free ONLY locks obeying POSIX
2312 * semantics, and not to free BSD-style file locks.
2313 * If the descriptor was in a message, POSIX-style locks
2314 * aren't passed with the descriptor.
2316 if (p != NULL && fp->f_type == DTYPE_VNODE &&
2317 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2320 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) {
2321 lf.l_whence = SEEK_SET;
2324 lf.l_type = F_UNLCK;
2325 vp = (struct vnode *)fp->f_data;
2326 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
2330 if (fdtol != NULL) {
2332 * Handle special case where file descriptor table
2333 * is shared between multiple process leaders.
2335 for (fdtol = fdtol->fdl_next;
2336 fdtol != p->p_fdtol;
2337 fdtol = fdtol->fdl_next) {
2338 if ((fdtol->fdl_leader->p_flag &
2341 fdtol->fdl_holdcount++;
2342 lf.l_whence = SEEK_SET;
2345 lf.l_type = F_UNLCK;
2346 vp = (struct vnode *)fp->f_data;
2347 (void) VOP_ADVLOCK(vp,
2348 (caddr_t)fdtol->fdl_leader,
2349 F_UNLCK, &lf, F_POSIX);
2350 fdtol->fdl_holdcount--;
2351 if (fdtol->fdl_holdcount == 0 &&
2352 fdtol->fdl_wakeup != 0) {
2353 fdtol->fdl_wakeup = 0;
2366 * fhold() can only be called if f_count is already at least 1 (i.e. the
2367 * caller of fhold() already has a reference to the file pointer in some
2370 * f_count is not spin-locked. Instead, atomic ops are used for
2371 * incrementing, decrementing, and handling the 1->0 transition.
2374 fhold(struct file *fp)
2376 atomic_add_int(&fp->f_count, 1);
2380 * fdrop() - drop a reference to a descriptor
2382 * MPALMOSTSAFE - acquires mplock for final close sequence
2385 fdrop(struct file *fp)
2392 * A combined fetch and subtract is needed to properly detect
2393 * 1->0 transitions, otherwise two cpus dropping from a ref
2394 * count of 2 might both try to run the 1->0 code.
2396 if (atomic_fetchadd_int(&fp->f_count, -1) > 1)
2399 KKASSERT(SLIST_FIRST(&fp->f_klist) == NULL);
2403 * The last reference has gone away, we own the fp structure free
2406 if (fp->f_count < 0)
2407 panic("fdrop: count < 0");
2408 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE &&
2409 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2411 lf.l_whence = SEEK_SET;
2414 lf.l_type = F_UNLCK;
2415 vp = (struct vnode *)fp->f_data;
2416 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2418 if (fp->f_ops != &badfileops)
2419 error = fo_close(fp);
2428 * Apply an advisory lock on a file descriptor.
2430 * Just attempt to get a record lock of the requested type on
2431 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
2436 sys_flock(struct flock_args *uap)
2438 struct proc *p = curproc;
2444 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
2447 if (fp->f_type != DTYPE_VNODE) {
2451 vp = (struct vnode *)fp->f_data;
2452 lf.l_whence = SEEK_SET;
2455 if (uap->how & LOCK_UN) {
2456 lf.l_type = F_UNLCK;
2457 fp->f_flag &= ~FHASLOCK;
2458 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2461 if (uap->how & LOCK_EX)
2462 lf.l_type = F_WRLCK;
2463 else if (uap->how & LOCK_SH)
2464 lf.l_type = F_RDLCK;
2469 fp->f_flag |= FHASLOCK;
2470 if (uap->how & LOCK_NB)
2471 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0);
2473 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT);
2481 * File Descriptor pseudo-device driver (/dev/fd/).
2483 * Opening minor device N dup()s the file (if any) connected to file
2484 * descriptor N belonging to the calling process. Note that this driver
2485 * consists of only the ``open()'' routine, because all subsequent
2486 * references to this file will be direct to the other driver.
2489 fdopen(struct dev_open_args *ap)
2491 thread_t td = curthread;
2493 KKASSERT(td->td_lwp != NULL);
2496 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the
2497 * the file descriptor being sought for duplication. The error
2498 * return ensures that the vnode for this device will be released
2499 * by vn_open. Open will detect this special error and take the
2500 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
2501 * will simply report the error.
2503 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev);
2508 * The caller has reserved the file descriptor dfd for us. On success we
2509 * must fsetfd() it. On failure the caller will clean it up.
2514 dupfdopen(struct filedesc *fdp, int dfd, int sfd, int mode, int error)
2520 if ((wfp = holdfp(fdp, sfd, -1)) == NULL)
2524 * Close a revoke/dup race. Duping a descriptor marked as revoked
2525 * will dup a dummy descriptor instead of the real one.
2527 if (wfp->f_flag & FREVOKED) {
2528 kprintf("Warning: attempt to dup() a revoked descriptor\n");
2531 werror = falloc(NULL, &wfp, NULL);
2537 * There are two cases of interest here.
2539 * For ENODEV simply dup sfd to file descriptor dfd and return.
2541 * For ENXIO steal away the file structure from sfd and store it
2542 * dfd. sfd is effectively closed by this operation.
2544 * Any other error code is just returned.
2549 * Check that the mode the file is being opened for is a
2550 * subset of the mode of the existing descriptor.
2552 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
2556 spin_lock(&fdp->fd_spin);
2557 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2558 fsetfd_locked(fdp, wfp, dfd);
2559 spin_unlock(&fdp->fd_spin);
2564 * Steal away the file pointer from dfd, and stuff it into indx.
2566 spin_lock(&fdp->fd_spin);
2567 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2568 fsetfd(fdp, wfp, dfd);
2569 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) {
2570 spin_unlock(&fdp->fd_spin);
2573 spin_unlock(&fdp->fd_spin);
2585 * NOT MPSAFE - I think these refer to a common file descriptor table
2586 * and we need to spinlock that to link fdtol in.
2588 struct filedesc_to_leader *
2589 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
2590 struct proc *leader)
2592 struct filedesc_to_leader *fdtol;
2594 fdtol = kmalloc(sizeof(struct filedesc_to_leader),
2595 M_FILEDESC_TO_LEADER, M_WAITOK);
2596 fdtol->fdl_refcount = 1;
2597 fdtol->fdl_holdcount = 0;
2598 fdtol->fdl_wakeup = 0;
2599 fdtol->fdl_leader = leader;
2601 fdtol->fdl_next = old->fdl_next;
2602 fdtol->fdl_prev = old;
2603 old->fdl_next = fdtol;
2604 fdtol->fdl_next->fdl_prev = fdtol;
2606 fdtol->fdl_next = fdtol;
2607 fdtol->fdl_prev = fdtol;
2613 * Scan all file pointers in the system. The callback is made with
2614 * the master list spinlock held exclusively.
2619 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data)
2624 spin_lock(&filehead_spin);
2625 LIST_FOREACH(fp, &filehead, f_list) {
2626 res = callback(fp, data);
2630 spin_unlock(&filehead_spin);
2634 * Get file structures.
2636 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe)
2639 struct sysctl_kern_file_info {
2642 struct sysctl_req *req;
2645 static int sysctl_kern_file_callback(struct proc *p, void *data);
2648 sysctl_kern_file(SYSCTL_HANDLER_ARGS)
2650 struct sysctl_kern_file_info info;
2653 * Note: because the number of file descriptors is calculated
2654 * in different ways for sizing vs returning the data,
2655 * there is information leakage from the first loop. However,
2656 * it is of a similar order of magnitude to the leakage from
2657 * global system statistics such as kern.openfiles.
2659 * When just doing a count, note that we cannot just count
2660 * the elements and add f_count via the filehead list because
2661 * threaded processes share their descriptor table and f_count might
2662 * still be '1' in that case.
2664 * Since the SYSCTL op can block, we must hold the process to
2665 * prevent it being ripped out from under us either in the
2666 * file descriptor loop or in the greater LIST_FOREACH. The
2667 * process may be in varying states of disrepair. If the process
2668 * is in SZOMB we may have caught it just as it is being removed
2669 * from the allproc list, we must skip it in that case to maintain
2670 * an unbroken chain through the allproc list.
2675 allproc_scan(sysctl_kern_file_callback, &info);
2678 * When just calculating the size, overestimate a bit to try to
2679 * prevent system activity from causing the buffer-fill call
2682 if (req->oldptr == NULL) {
2683 info.count = (info.count + 16) + (info.count / 10);
2684 info.error = SYSCTL_OUT(req, NULL,
2685 info.count * sizeof(struct kinfo_file));
2687 return (info.error);
2691 sysctl_kern_file_callback(struct proc *p, void *data)
2693 struct sysctl_kern_file_info *info = data;
2694 struct kinfo_file kf;
2695 struct filedesc *fdp;
2700 if (p->p_stat == SIDL || p->p_stat == SZOMB)
2702 if (!PRISON_CHECK(info->req->td->td_ucred, p->p_ucred) != 0)
2706 * Softref the fdp to prevent it from being destroyed
2708 spin_lock(&p->p_spin);
2709 if ((fdp = p->p_fd) == NULL) {
2710 spin_unlock(&p->p_spin);
2713 atomic_add_int(&fdp->fd_softrefs, 1);
2714 spin_unlock(&p->p_spin);
2717 * The fdp's own spinlock prevents the contents from being
2720 spin_lock(&fdp->fd_spin);
2721 for (n = 0; n < fdp->fd_nfiles; ++n) {
2722 if ((fp = fdp->fd_files[n].fp) == NULL)
2724 if (info->req->oldptr == NULL) {
2727 uid = p->p_ucred ? p->p_ucred->cr_uid : -1;
2728 kcore_make_file(&kf, fp, p->p_pid, uid, n);
2729 spin_unlock(&fdp->fd_spin);
2730 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf));
2731 spin_lock(&fdp->fd_spin);
2736 spin_unlock(&fdp->fd_spin);
2737 atomic_subtract_int(&fdp->fd_softrefs, 1);
2743 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
2744 0, 0, sysctl_kern_file, "S,file", "Entire file table");
2746 SYSCTL_INT(_kern, OID_AUTO, minfilesperproc, CTLFLAG_RW,
2747 &minfilesperproc, 0, "Minimum files allowed open per process");
2748 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
2749 &maxfilesperproc, 0, "Maximum files allowed open per process");
2750 SYSCTL_INT(_kern, OID_AUTO, maxfilesperuser, CTLFLAG_RW,
2751 &maxfilesperuser, 0, "Maximum files allowed open per user");
2753 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
2754 &maxfiles, 0, "Maximum number of files");
2756 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW,
2757 &maxfilesrootres, 0, "Descriptors reserved for root use");
2759 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
2760 &nfiles, 0, "System-wide number of open files");
2763 fildesc_drvinit(void *unused)
2767 for (fd = 0; fd < NUMFDESC; fd++) {
2768 make_dev(&fildesc_ops, fd,
2769 UID_BIN, GID_BIN, 0666, "fd/%d", fd);
2772 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin");
2773 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout");
2774 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr");
2780 struct fileops badfileops = {
2781 .fo_read = badfo_readwrite,
2782 .fo_write = badfo_readwrite,
2783 .fo_ioctl = badfo_ioctl,
2784 .fo_poll = badfo_poll,
2785 .fo_kqfilter = badfo_kqfilter,
2786 .fo_stat = badfo_stat,
2787 .fo_close = badfo_close,
2788 .fo_shutdown = badfo_shutdown
2802 badfo_ioctl(struct file *fp, u_long com, caddr_t data,
2803 struct ucred *cred, struct sysmsg *msgv)
2809 badfo_poll(struct file *fp, int events, struct ucred *cred)
2815 * Must return an error to prevent registration, typically
2816 * due to a revoked descriptor (file_filtops assigned).
2819 badfo_kqfilter(struct file *fp, struct knote *kn)
2821 return (EOPNOTSUPP);
2828 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred)
2837 badfo_close(struct file *fp)
2846 badfo_shutdown(struct file *fp, int how)
2855 nofo_shutdown(struct file *fp, int how)
2857 return (EOPNOTSUPP);
2860 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
2861 fildesc_drvinit,NULL)