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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8 * modification, are permitted provided that the following conditions
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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 $
75 #include "opt_compat.h"
76 #include <sys/param.h>
77 #include <sys/systm.h>
78 #include <sys/malloc.h>
79 #include <sys/sysproto.h>
81 #include <sys/device.h>
83 #include <sys/filedesc.h>
84 #include <sys/kernel.h>
85 #include <sys/sysctl.h>
86 #include <sys/vnode.h>
88 #include <sys/nlookup.h>
91 #include <sys/filio.h>
92 #include <sys/fcntl.h>
93 #include <sys/unistd.h>
94 #include <sys/resourcevar.h>
95 #include <sys/event.h>
96 #include <sys/kern_syscall.h>
97 #include <sys/kcore.h>
98 #include <sys/kinfo.h>
102 #include <vm/vm_extern.h>
104 #include <sys/thread2.h>
105 #include <sys/file2.h>
106 #include <sys/spinlock2.h>
107 #include <sys/mplock2.h>
109 static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd);
110 static void fdreserve_locked (struct filedesc *fdp, int fd0, int incr);
111 static struct file *funsetfd_locked (struct filedesc *fdp, int fd);
112 static void ffree(struct file *fp);
114 static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table");
115 static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader",
116 "file desc to leader structures");
117 MALLOC_DEFINE(M_FILE, "file", "Open file structure");
118 static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures");
120 static struct krate krate_uidinfo = { .freq = 1 };
122 static d_open_t fdopen;
125 #define CDEV_MAJOR 22
126 static struct dev_ops fildesc_ops = {
132 * Descriptor management.
134 static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead);
135 static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin);
136 static int nfiles; /* actual number of open files */
140 * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared.
142 * MPSAFE - must be called with fdp->fd_spin exclusively held
146 fdfixup_locked(struct filedesc *fdp, int fd)
148 if (fd < fdp->fd_freefile) {
149 fdp->fd_freefile = fd;
151 while (fdp->fd_lastfile >= 0 &&
152 fdp->fd_files[fdp->fd_lastfile].fp == NULL &&
153 fdp->fd_files[fdp->fd_lastfile].reserved == 0
160 * System calls on descriptors.
165 sys_getdtablesize(struct getdtablesize_args *uap)
167 struct proc *p = curproc;
168 struct plimit *limit = p->p_limit;
171 spin_lock(&limit->p_spin);
172 if (limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
175 dtsize = (int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur;
176 spin_unlock(&limit->p_spin);
178 if (dtsize > maxfilesperproc)
179 dtsize = maxfilesperproc;
180 if (dtsize < minfilesperproc)
181 dtsize = minfilesperproc;
182 if (p->p_ucred->cr_uid && dtsize > maxfilesperuser)
183 dtsize = maxfilesperuser;
184 uap->sysmsg_result = dtsize;
189 * Duplicate a file descriptor to a particular value.
191 * note: keep in mind that a potential race condition exists when closing
192 * descriptors from a shared descriptor table (via rfork).
197 sys_dup2(struct dup2_args *uap)
202 error = kern_dup(DUP_FIXED, uap->from, uap->to, &fd);
203 uap->sysmsg_fds[0] = fd;
209 * Duplicate a file descriptor.
214 sys_dup(struct dup_args *uap)
219 error = kern_dup(DUP_VARIABLE, uap->fd, 0, &fd);
220 uap->sysmsg_fds[0] = fd;
226 * MPALMOSTSAFE - acquires mplock for fp operations
229 kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred)
231 struct thread *td = curthread;
232 struct proc *p = td->td_proc;
238 int tmp, error, flg = F_POSIX;
243 * Operations on file descriptors that do not require a file pointer.
247 error = fgetfdflags(p->p_fd, fd, &tmp);
249 dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0;
253 if (dat->fc_cloexec & FD_CLOEXEC)
254 error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE);
256 error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE);
260 error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd);
267 * Operations on file pointers
269 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
275 dat->fc_flags = OFLAGS(fp->f_flag);
281 nflags = FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS;
282 nflags |= oflags & ~FCNTLFLAGS;
285 if (((nflags ^ oflags) & O_APPEND) && (oflags & FAPPENDONLY))
287 if (error == 0 && ((nflags ^ oflags) & FASYNC)) {
288 tmp = nflags & FASYNC;
289 error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp,
297 error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner,
302 error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner,
308 /* Fall into F_SETLK */
311 if (fp->f_type != DTYPE_VNODE) {
315 vp = (struct vnode *)fp->f_data;
318 * copyin/lockop may block
320 if (dat->fc_flock.l_whence == SEEK_CUR)
321 dat->fc_flock.l_start += fp->f_offset;
323 switch (dat->fc_flock.l_type) {
325 if ((fp->f_flag & FREAD) == 0) {
329 p->p_leader->p_flag |= P_ADVLOCK;
330 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
331 &dat->fc_flock, flg);
334 if ((fp->f_flag & FWRITE) == 0) {
338 p->p_leader->p_flag |= P_ADVLOCK;
339 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK,
340 &dat->fc_flock, flg);
343 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
344 &dat->fc_flock, F_POSIX);
352 * It is possible to race a close() on the descriptor while
353 * we were blocked getting the lock. If this occurs the
354 * close might not have caught the lock.
356 if (checkfdclosed(p->p_fd, fd, fp)) {
357 dat->fc_flock.l_whence = SEEK_SET;
358 dat->fc_flock.l_start = 0;
359 dat->fc_flock.l_len = 0;
360 dat->fc_flock.l_type = F_UNLCK;
361 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader,
362 F_UNLCK, &dat->fc_flock, F_POSIX);
367 if (fp->f_type != DTYPE_VNODE) {
371 vp = (struct vnode *)fp->f_data;
373 * copyin/lockop may block
375 if (dat->fc_flock.l_type != F_RDLCK &&
376 dat->fc_flock.l_type != F_WRLCK &&
377 dat->fc_flock.l_type != F_UNLCK) {
381 if (dat->fc_flock.l_whence == SEEK_CUR)
382 dat->fc_flock.l_start += fp->f_offset;
383 error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK,
384 &dat->fc_flock, F_POSIX);
397 * The file control system call.
402 sys_fcntl(struct fcntl_args *uap)
409 dat.fc_fd = uap->arg;
412 dat.fc_cloexec = uap->arg;
415 dat.fc_flags = uap->arg;
418 dat.fc_owner = uap->arg;
423 error = copyin((caddr_t)uap->arg, &dat.fc_flock,
424 sizeof(struct flock));
430 error = kern_fcntl(uap->fd, uap->cmd, &dat, curthread->td_ucred);
435 uap->sysmsg_result = dat.fc_fd;
438 uap->sysmsg_result = dat.fc_cloexec;
441 uap->sysmsg_result = dat.fc_flags;
444 uap->sysmsg_result = dat.fc_owner;
446 error = copyout(&dat.fc_flock, (caddr_t)uap->arg,
447 sizeof(struct flock));
456 * Common code for dup, dup2, and fcntl(F_DUPFD).
458 * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells
459 * kern_dup() to destructively dup over an existing file descriptor if new
460 * is already open. DUP_VARIABLE tells kern_dup() to find the lowest
461 * unused file descriptor that is greater than or equal to new.
466 kern_dup(enum dup_type type, int old, int new, int *res)
468 struct thread *td = curthread;
469 struct proc *p = td->td_proc;
470 struct filedesc *fdp = p->p_fd;
479 * Verify that we have a valid descriptor to dup from and
480 * possibly to dup to.
482 * NOTE: maxfilesperuser is not applicable to dup()
485 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
488 dtsize = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
489 if (dtsize > maxfilesperproc)
490 dtsize = maxfilesperproc;
491 if (dtsize < minfilesperproc)
492 dtsize = minfilesperproc;
494 if (new < 0 || new > dtsize)
497 spin_lock(&fdp->fd_spin);
498 if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) {
499 spin_unlock(&fdp->fd_spin);
502 if (type == DUP_FIXED && old == new) {
504 spin_unlock(&fdp->fd_spin);
507 fp = fdp->fd_files[old].fp;
508 oldflags = fdp->fd_files[old].fileflags;
509 fhold(fp); /* MPSAFE - can be called with a spinlock held */
512 * Allocate a new descriptor if DUP_VARIABLE, or expand the table
513 * if the requested descriptor is beyond the current table size.
515 * This can block. Retry if the source descriptor no longer matches
516 * or if our expectation in the expansion case races.
518 * If we are not expanding or allocating a new decriptor, then reset
519 * the target descriptor to a reserved state so we have a uniform
520 * setup for the next code block.
522 if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) {
523 spin_unlock(&fdp->fd_spin);
524 error = fdalloc(p, new, &newfd);
525 spin_lock(&fdp->fd_spin);
527 spin_unlock(&fdp->fd_spin);
534 if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) {
535 fsetfd_locked(fdp, NULL, newfd);
536 spin_unlock(&fdp->fd_spin);
541 * Check for expansion race
543 if (type != DUP_VARIABLE && new != newfd) {
544 fsetfd_locked(fdp, NULL, newfd);
545 spin_unlock(&fdp->fd_spin);
550 * Check for ripout, newfd reused old (this case probably
554 fsetfd_locked(fdp, NULL, newfd);
555 spin_unlock(&fdp->fd_spin);
562 if (fdp->fd_files[new].reserved) {
563 spin_unlock(&fdp->fd_spin);
565 kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new);
566 tsleep(fdp, 0, "fdres", hz);
571 * If the target descriptor was never allocated we have
572 * to allocate it. If it was we have to clean out the
573 * old descriptor. delfp inherits the ref from the
576 delfp = fdp->fd_files[new].fp;
577 fdp->fd_files[new].fp = NULL;
578 fdp->fd_files[new].reserved = 1;
580 fdreserve_locked(fdp, new, 1);
581 if (new > fdp->fd_lastfile)
582 fdp->fd_lastfile = new;
588 * NOTE: still holding an exclusive spinlock
592 * If a descriptor is being overwritten we may hve to tell
593 * fdfree() to sleep to ensure that all relevant process
594 * leaders can be traversed in closef().
596 if (delfp != NULL && p->p_fdtol != NULL) {
597 fdp->fd_holdleaderscount++;
602 KASSERT(delfp == NULL || type == DUP_FIXED,
603 ("dup() picked an open file"));
606 * Duplicate the source descriptor, update lastfile. If the new
607 * descriptor was not allocated and we aren't replacing an existing
608 * descriptor we have to mark the descriptor as being in use.
610 * The fd_files[] array inherits fp's hold reference.
612 fsetfd_locked(fdp, fp, new);
613 fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE;
614 spin_unlock(&fdp->fd_spin);
619 * If we dup'd over a valid file, we now own the reference to it
620 * and must dispose of it using closef() semantics (as if a
621 * close() were performed on it).
624 if (SLIST_FIRST(&delfp->f_klist))
625 knote_fdclose(delfp, fdp, new);
628 spin_lock(&fdp->fd_spin);
629 fdp->fd_holdleaderscount--;
630 if (fdp->fd_holdleaderscount == 0 &&
631 fdp->fd_holdleaderswakeup != 0) {
632 fdp->fd_holdleaderswakeup = 0;
633 spin_unlock(&fdp->fd_spin);
634 wakeup(&fdp->fd_holdleaderscount);
636 spin_unlock(&fdp->fd_spin);
644 * If sigio is on the list associated with a process or process group,
645 * disable signalling from the device, remove sigio from the list and
649 funsetown(struct sigio *sigio)
654 *(sigio->sio_myref) = NULL;
656 if (sigio->sio_pgid < 0) {
657 SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio,
659 } else /* if ((*sigiop)->sio_pgid > 0) */ {
660 SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio,
663 crfree(sigio->sio_ucred);
664 kfree(sigio, M_SIGIO);
667 /* Free a list of sigio structures. */
669 funsetownlst(struct sigiolst *sigiolst)
673 while ((sigio = SLIST_FIRST(sigiolst)) != NULL)
678 * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg).
680 * After permission checking, add a sigio structure to the sigio list for
681 * the process or process group.
684 fsetown(pid_t pgid, struct sigio **sigiop)
700 * Policy - Don't allow a process to FSETOWN a process
701 * in another session.
703 * Remove this test to allow maximum flexibility or
704 * restrict FSETOWN to the current process or process
705 * group for maximum safety.
707 if (proc->p_session != curproc->p_session)
711 } else /* if (pgid < 0) */ {
712 pgrp = pgfind(-pgid);
717 * Policy - Don't allow a process to FSETOWN a process
718 * in another session.
720 * Remove this test to allow maximum flexibility or
721 * restrict FSETOWN to the current process or process
722 * group for maximum safety.
724 if (pgrp->pg_session != curproc->p_session)
730 sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK);
732 SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
733 sigio->sio_proc = proc;
735 SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio);
736 sigio->sio_pgrp = pgrp;
738 sigio->sio_pgid = pgid;
739 sigio->sio_ucred = crhold(curthread->td_ucred);
740 /* It would be convenient if p_ruid was in ucred. */
741 sigio->sio_ruid = sigio->sio_ucred->cr_ruid;
742 sigio->sio_myref = sigiop;
750 * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg).
753 fgetown(struct sigio *sigio)
755 return (sigio != NULL ? sigio->sio_pgid : 0);
759 * Close many file descriptors.
764 sys_closefrom(struct closefrom_args *uap)
766 return(kern_closefrom(uap->fd));
770 * Close all file descriptors greater then or equal to fd
775 kern_closefrom(int fd)
777 struct thread *td = curthread;
778 struct proc *p = td->td_proc;
779 struct filedesc *fdp;
788 * NOTE: This function will skip unassociated descriptors and
789 * reserved descriptors that have not yet been assigned.
790 * fd_lastfile can change as a side effect of kern_close().
792 spin_lock(&fdp->fd_spin);
793 while (fd <= fdp->fd_lastfile) {
794 if (fdp->fd_files[fd].fp != NULL) {
795 spin_unlock(&fdp->fd_spin);
796 /* ok if this races another close */
797 if (kern_close(fd) == EINTR)
799 spin_lock(&fdp->fd_spin);
803 spin_unlock(&fdp->fd_spin);
808 * Close a file descriptor.
813 sys_close(struct close_args *uap)
815 return(kern_close(uap->fd));
824 struct thread *td = curthread;
825 struct proc *p = td->td_proc;
826 struct filedesc *fdp;
834 spin_lock(&fdp->fd_spin);
835 if ((fp = funsetfd_locked(fdp, fd)) == NULL) {
836 spin_unlock(&fdp->fd_spin);
840 if (p->p_fdtol != NULL) {
842 * Ask fdfree() to sleep to ensure that all relevant
843 * process leaders can be traversed in closef().
845 fdp->fd_holdleaderscount++;
850 * we now hold the fp reference that used to be owned by the descriptor
853 spin_unlock(&fdp->fd_spin);
854 if (SLIST_FIRST(&fp->f_klist))
855 knote_fdclose(fp, fdp, fd);
856 error = closef(fp, p);
858 spin_lock(&fdp->fd_spin);
859 fdp->fd_holdleaderscount--;
860 if (fdp->fd_holdleaderscount == 0 &&
861 fdp->fd_holdleaderswakeup != 0) {
862 fdp->fd_holdleaderswakeup = 0;
863 spin_unlock(&fdp->fd_spin);
864 wakeup(&fdp->fd_holdleaderscount);
866 spin_unlock(&fdp->fd_spin);
873 * shutdown_args(int fd, int how)
876 kern_shutdown(int fd, int how)
878 struct thread *td = curthread;
879 struct proc *p = td->td_proc;
885 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
887 error = fo_shutdown(fp, how);
897 sys_shutdown(struct shutdown_args *uap)
902 error = kern_shutdown(uap->s, uap->how);
912 kern_fstat(int fd, struct stat *ub)
914 struct thread *td = curthread;
915 struct proc *p = td->td_proc;
921 if ((fp = holdfp(p->p_fd, fd, -1)) == NULL)
923 error = fo_stat(fp, ub, td->td_ucred);
930 * Return status information about a file descriptor.
935 sys_fstat(struct fstat_args *uap)
940 error = kern_fstat(uap->fd, &st);
943 error = copyout(&st, uap->sb, sizeof(st));
948 * Return pathconf information about a file descriptor.
953 sys_fpathconf(struct fpathconf_args *uap)
955 struct thread *td = curthread;
956 struct proc *p = td->td_proc;
961 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
964 switch (fp->f_type) {
967 if (uap->name != _PC_PIPE_BUF) {
970 uap->sysmsg_result = PIPE_BUF;
976 vp = (struct vnode *)fp->f_data;
978 error = VOP_PATHCONF(vp, uap->name, &uap->sysmsg_reg);
990 SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand, 0,
991 "Number of times a file table has been expanded");
994 * Grow the file table so it can hold through descriptor (want).
996 * The fdp's spinlock must be held exclusively on entry and may be held
997 * exclusively on return. The spinlock may be cycled by the routine.
1002 fdgrow_locked(struct filedesc *fdp, int want)
1004 struct fdnode *newfiles;
1005 struct fdnode *oldfiles;
1008 nf = fdp->fd_nfiles;
1010 /* nf has to be of the form 2^n - 1 */
1012 } while (nf <= want);
1014 spin_unlock(&fdp->fd_spin);
1015 newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK);
1016 spin_lock(&fdp->fd_spin);
1019 * We could have raced another extend while we were not holding
1022 if (fdp->fd_nfiles >= nf) {
1023 spin_unlock(&fdp->fd_spin);
1024 kfree(newfiles, M_FILEDESC);
1025 spin_lock(&fdp->fd_spin);
1029 * Copy the existing ofile and ofileflags arrays
1030 * and zero the new portion of each array.
1032 extra = nf - fdp->fd_nfiles;
1033 bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode));
1034 bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode));
1036 oldfiles = fdp->fd_files;
1037 fdp->fd_files = newfiles;
1038 fdp->fd_nfiles = nf;
1040 if (oldfiles != fdp->fd_builtin_files) {
1041 spin_unlock(&fdp->fd_spin);
1042 kfree(oldfiles, M_FILEDESC);
1043 spin_lock(&fdp->fd_spin);
1049 * Number of nodes in right subtree, including the root.
1052 right_subtree_size(int n)
1054 return (n ^ (n | (n + 1)));
1061 right_ancestor(int n)
1063 return (n | (n + 1));
1070 left_ancestor(int n)
1072 return ((n & (n + 1)) - 1);
1076 * Traverse the in-place binary tree buttom-up adjusting the allocation
1077 * count so scans can determine where free descriptors are located.
1079 * MPSAFE - caller must be holding an exclusive spinlock on fdp
1083 fdreserve_locked(struct filedesc *fdp, int fd, int incr)
1086 fdp->fd_files[fd].allocated += incr;
1087 KKASSERT(fdp->fd_files[fd].allocated >= 0);
1088 fd = left_ancestor(fd);
1093 * Reserve a file descriptor for the process. If no error occurs, the
1094 * caller MUST at some point call fsetfd() or assign a file pointer
1095 * or dispose of the reservation.
1100 fdalloc(struct proc *p, int want, int *result)
1102 struct filedesc *fdp = p->p_fd;
1103 struct uidinfo *uip;
1104 int fd, rsize, rsum, node, lim;
1107 * Check dtable size limit
1109 spin_lock(&p->p_limit->p_spin);
1110 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
1113 lim = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
1114 spin_unlock(&p->p_limit->p_spin);
1116 if (lim > maxfilesperproc)
1117 lim = maxfilesperproc;
1118 if (lim < minfilesperproc)
1119 lim = minfilesperproc;
1124 * Check that the user has not run out of descriptors (non-root only).
1125 * As a safety measure the dtable is allowed to have at least
1126 * minfilesperproc open fds regardless of the maxfilesperuser limit.
1128 if (p->p_ucred->cr_uid && fdp->fd_nfiles >= minfilesperproc) {
1129 uip = p->p_ucred->cr_uidinfo;
1130 if (uip->ui_openfiles > maxfilesperuser) {
1131 krateprintf(&krate_uidinfo,
1132 "Warning: user %d pid %d (%s) ran out of "
1133 "file descriptors (%d/%d)\n",
1134 p->p_ucred->cr_uid, (int)p->p_pid,
1136 uip->ui_openfiles, maxfilesperuser);
1142 * Grow the dtable if necessary
1144 spin_lock(&fdp->fd_spin);
1145 if (want >= fdp->fd_nfiles)
1146 fdgrow_locked(fdp, want);
1149 * Search for a free descriptor starting at the higher
1150 * of want or fd_freefile. If that fails, consider
1151 * expanding the ofile array.
1153 * NOTE! the 'allocated' field is a cumulative recursive allocation
1154 * count. If we happen to see a value of 0 then we can shortcut
1155 * our search. Otherwise we run through through the tree going
1156 * down branches we know have free descriptor(s) until we hit a
1157 * leaf node. The leaf node will be free but will not necessarily
1158 * have an allocated field of 0.
1161 /* move up the tree looking for a subtree with a free node */
1162 for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim);
1163 fd = right_ancestor(fd)) {
1164 if (fdp->fd_files[fd].allocated == 0)
1167 rsize = right_subtree_size(fd);
1168 if (fdp->fd_files[fd].allocated == rsize)
1169 continue; /* right subtree full */
1172 * Free fd is in the right subtree of the tree rooted at fd.
1173 * Call that subtree R. Look for the smallest (leftmost)
1174 * subtree of R with an unallocated fd: continue moving
1175 * down the left branch until encountering a full left
1176 * subtree, then move to the right.
1178 for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) {
1180 rsum += fdp->fd_files[node].allocated;
1181 if (fdp->fd_files[fd].allocated == rsum + rsize) {
1182 fd = node; /* move to the right */
1183 if (fdp->fd_files[node].allocated == 0)
1192 * No space in current array. Expand?
1194 if (fdp->fd_nfiles >= lim) {
1195 spin_unlock(&fdp->fd_spin);
1198 fdgrow_locked(fdp, want);
1202 KKASSERT(fd < fdp->fd_nfiles);
1203 if (fd > fdp->fd_lastfile)
1204 fdp->fd_lastfile = fd;
1205 if (want <= fdp->fd_freefile)
1206 fdp->fd_freefile = fd;
1208 KKASSERT(fdp->fd_files[fd].fp == NULL);
1209 KKASSERT(fdp->fd_files[fd].reserved == 0);
1210 fdp->fd_files[fd].fileflags = 0;
1211 fdp->fd_files[fd].reserved = 1;
1212 fdreserve_locked(fdp, fd, 1);
1213 spin_unlock(&fdp->fd_spin);
1218 * Check to see whether n user file descriptors
1219 * are available to the process p.
1224 fdavail(struct proc *p, int n)
1226 struct filedesc *fdp = p->p_fd;
1227 struct fdnode *fdnode;
1230 spin_lock(&p->p_limit->p_spin);
1231 if (p->p_rlimit[RLIMIT_NOFILE].rlim_cur > INT_MAX)
1234 lim = (int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur;
1235 spin_unlock(&p->p_limit->p_spin);
1237 if (lim > maxfilesperproc)
1238 lim = maxfilesperproc;
1239 if (lim < minfilesperproc)
1240 lim = minfilesperproc;
1242 spin_lock(&fdp->fd_spin);
1243 if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) {
1244 spin_unlock(&fdp->fd_spin);
1247 last = min(fdp->fd_nfiles, lim);
1248 fdnode = &fdp->fd_files[fdp->fd_freefile];
1249 for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) {
1250 if (fdnode->fp == NULL && --n <= 0) {
1251 spin_unlock(&fdp->fd_spin);
1255 spin_unlock(&fdp->fd_spin);
1260 * Revoke open descriptors referencing (f_data, f_type)
1262 * Any revoke executed within a prison is only able to
1263 * revoke descriptors for processes within that prison.
1265 * Returns 0 on success or an error code.
1267 struct fdrevoke_info {
1277 static int fdrevoke_check_callback(struct file *fp, void *vinfo);
1278 static int fdrevoke_proc_callback(struct proc *p, void *vinfo);
1281 fdrevoke(void *f_data, short f_type, struct ucred *cred)
1283 struct fdrevoke_info info;
1286 bzero(&info, sizeof(info));
1290 error = falloc(NULL, &info.nfp, NULL);
1295 * Scan the file pointer table once. dups do not dup file pointers,
1296 * only descriptors, so there is no leak. Set FREVOKED on the fps
1299 allfiles_scan_exclusive(fdrevoke_check_callback, &info);
1302 * If any fps were marked track down the related descriptors
1303 * and close them. Any dup()s at this point will notice
1304 * the FREVOKED already set in the fp and do the right thing.
1306 * Any fps with non-zero msgcounts (aka sent over a unix-domain
1307 * socket) bumped the intransit counter and will require a
1308 * scan. Races against fps leaving the socket are closed by
1309 * the socket code checking for FREVOKED.
1312 allproc_scan(fdrevoke_proc_callback, &info);
1314 unp_revoke_gc(info.nfp);
1320 * Locate matching file pointers directly.
1322 * WARNING: allfiles_scan_exclusive() holds a spinlock through these calls!
1325 fdrevoke_check_callback(struct file *fp, void *vinfo)
1327 struct fdrevoke_info *info = vinfo;
1330 * File pointers already flagged for revokation are skipped.
1332 if (fp->f_flag & FREVOKED)
1336 * If revoking from a prison file pointers created outside of
1337 * that prison, or file pointers without creds, cannot be revoked.
1339 if (info->cred->cr_prison &&
1340 (fp->f_cred == NULL ||
1341 info->cred->cr_prison != fp->f_cred->cr_prison)) {
1346 * If the file pointer matches then mark it for revocation. The
1347 * flag is currently only used by unp_revoke_gc().
1349 * info->count is a heuristic and can race in a SMP environment.
1351 if (info->data == fp->f_data && info->type == fp->f_type) {
1352 atomic_set_int(&fp->f_flag, FREVOKED);
1353 info->count += fp->f_count;
1361 * Locate matching file pointers via process descriptor tables.
1364 fdrevoke_proc_callback(struct proc *p, void *vinfo)
1366 struct fdrevoke_info *info = vinfo;
1367 struct filedesc *fdp;
1371 if (p->p_stat == SIDL || p->p_stat == SZOMB)
1373 if (info->cred->cr_prison &&
1374 info->cred->cr_prison != p->p_ucred->cr_prison) {
1379 * If the controlling terminal of the process matches the
1380 * vnode being revoked we clear the controlling terminal.
1382 * The normal spec_close() may not catch this because it
1383 * uses curproc instead of p.
1385 if (p->p_session && info->type == DTYPE_VNODE &&
1386 info->data == p->p_session->s_ttyvp) {
1387 p->p_session->s_ttyvp = NULL;
1392 * Softref the fdp to prevent it from being destroyed
1394 spin_lock(&p->p_spin);
1395 if ((fdp = p->p_fd) == NULL) {
1396 spin_unlock(&p->p_spin);
1399 atomic_add_int(&fdp->fd_softrefs, 1);
1400 spin_unlock(&p->p_spin);
1403 * Locate and close any matching file descriptors.
1405 spin_lock(&fdp->fd_spin);
1406 for (n = 0; n < fdp->fd_nfiles; ++n) {
1407 if ((fp = fdp->fd_files[n].fp) == NULL)
1409 if (fp->f_flag & FREVOKED) {
1411 fdp->fd_files[n].fp = info->nfp;
1412 spin_unlock(&fdp->fd_spin);
1413 knote_fdclose(fp, fdp, n); /* XXX */
1415 spin_lock(&fdp->fd_spin);
1419 spin_unlock(&fdp->fd_spin);
1420 atomic_subtract_int(&fdp->fd_softrefs, 1);
1426 * Create a new open file structure and reserve a file decriptor
1427 * for the process that refers to it.
1429 * Root creds are checked using lp, or assumed if lp is NULL. If
1430 * resultfd is non-NULL then lp must also be non-NULL. No file
1431 * descriptor is reserved (and no process context is needed) if
1434 * A file pointer with a refcount of 1 is returned. Note that the
1435 * file pointer is NOT associated with the descriptor. If falloc
1436 * returns success, fsetfd() MUST be called to either associate the
1437 * file pointer or clear the reservation.
1442 falloc(struct lwp *lp, struct file **resultfp, int *resultfd)
1444 static struct timeval lastfail;
1447 struct ucred *cred = lp ? lp->lwp_thread->td_ucred : proc0.p_ucred;
1453 * Handle filetable full issues and root overfill.
1455 if (nfiles >= maxfiles - maxfilesrootres &&
1456 (cred->cr_ruid != 0 || nfiles >= maxfiles)) {
1457 if (ppsratecheck(&lastfail, &curfail, 1)) {
1458 kprintf("kern.maxfiles limit exceeded by uid %d, "
1459 "please see tuning(7).\n",
1467 * Allocate a new file descriptor.
1469 fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO);
1470 spin_init(&fp->f_spin);
1471 SLIST_INIT(&fp->f_klist);
1473 fp->f_ops = &badfileops;
1476 spin_lock(&filehead_spin);
1478 LIST_INSERT_HEAD(&filehead, fp, f_list);
1479 spin_unlock(&filehead_spin);
1481 if ((error = fdalloc(lp->lwp_proc, 0, resultfd)) != 0) {
1494 * Check for races against a file descriptor by determining that the
1495 * file pointer is still associated with the specified file descriptor,
1496 * and a close is not currently in progress.
1501 checkfdclosed(struct filedesc *fdp, int fd, struct file *fp)
1505 spin_lock(&fdp->fd_spin);
1506 if ((unsigned)fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp)
1510 spin_unlock(&fdp->fd_spin);
1515 * Associate a file pointer with a previously reserved file descriptor.
1516 * This function always succeeds.
1518 * If fp is NULL, the file descriptor is returned to the pool.
1522 * MPSAFE (exclusive spinlock must be held on call)
1525 fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd)
1527 KKASSERT((unsigned)fd < fdp->fd_nfiles);
1528 KKASSERT(fdp->fd_files[fd].reserved != 0);
1531 fdp->fd_files[fd].fp = fp;
1532 fdp->fd_files[fd].reserved = 0;
1534 fdp->fd_files[fd].reserved = 0;
1535 fdreserve_locked(fdp, fd, -1);
1536 fdfixup_locked(fdp, fd);
1544 fsetfd(struct filedesc *fdp, struct file *fp, int fd)
1546 spin_lock(&fdp->fd_spin);
1547 fsetfd_locked(fdp, fp, fd);
1548 spin_unlock(&fdp->fd_spin);
1552 * MPSAFE (exclusive spinlock must be held on call)
1556 funsetfd_locked(struct filedesc *fdp, int fd)
1560 if ((unsigned)fd >= fdp->fd_nfiles)
1562 if ((fp = fdp->fd_files[fd].fp) == NULL)
1564 fdp->fd_files[fd].fp = NULL;
1565 fdp->fd_files[fd].fileflags = 0;
1567 fdreserve_locked(fdp, fd, -1);
1568 fdfixup_locked(fdp, fd);
1576 fgetfdflags(struct filedesc *fdp, int fd, int *flagsp)
1580 spin_lock(&fdp->fd_spin);
1581 if (((u_int)fd) >= fdp->fd_nfiles) {
1583 } else if (fdp->fd_files[fd].fp == NULL) {
1586 *flagsp = fdp->fd_files[fd].fileflags;
1589 spin_unlock(&fdp->fd_spin);
1597 fsetfdflags(struct filedesc *fdp, int fd, int add_flags)
1601 spin_lock(&fdp->fd_spin);
1602 if (((u_int)fd) >= fdp->fd_nfiles) {
1604 } else if (fdp->fd_files[fd].fp == NULL) {
1607 fdp->fd_files[fd].fileflags |= add_flags;
1610 spin_unlock(&fdp->fd_spin);
1618 fclrfdflags(struct filedesc *fdp, int fd, int rem_flags)
1622 spin_lock(&fdp->fd_spin);
1623 if (((u_int)fd) >= fdp->fd_nfiles) {
1625 } else if (fdp->fd_files[fd].fp == NULL) {
1628 fdp->fd_files[fd].fileflags &= ~rem_flags;
1631 spin_unlock(&fdp->fd_spin);
1636 * Set/Change/Clear the creds for a fp and synchronize the uidinfo.
1639 fsetcred(struct file *fp, struct ucred *ncr)
1642 struct uidinfo *uip;
1645 if (ocr == NULL || ncr == NULL || ocr->cr_uidinfo != ncr->cr_uidinfo) {
1647 uip = ocr->cr_uidinfo;
1648 atomic_add_int(&uip->ui_openfiles, -1);
1651 uip = ncr->cr_uidinfo;
1652 atomic_add_int(&uip->ui_openfiles, 1);
1663 * Free a file descriptor.
1667 ffree(struct file *fp)
1669 KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!"));
1670 spin_lock(&filehead_spin);
1671 LIST_REMOVE(fp, f_list);
1673 spin_unlock(&filehead_spin);
1675 if (fp->f_nchandle.ncp)
1676 cache_drop(&fp->f_nchandle);
1681 * called from init_main, initialize filedesc0 for proc0.
1684 fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask)
1688 fdp0->fd_refcnt = 1;
1689 fdp0->fd_cmask = cmask;
1690 fdp0->fd_files = fdp0->fd_builtin_files;
1691 fdp0->fd_nfiles = NDFILE;
1692 fdp0->fd_lastfile = -1;
1693 spin_init(&fdp0->fd_spin);
1697 * Build a new filedesc structure.
1702 fdinit(struct proc *p)
1704 struct filedesc *newfdp;
1705 struct filedesc *fdp = p->p_fd;
1707 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO);
1708 spin_lock(&fdp->fd_spin);
1710 newfdp->fd_cdir = fdp->fd_cdir;
1711 vref(newfdp->fd_cdir);
1712 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1716 * rdir may not be set in e.g. proc0 or anything vm_fork'd off of
1717 * proc0, but should unconditionally exist in other processes.
1720 newfdp->fd_rdir = fdp->fd_rdir;
1721 vref(newfdp->fd_rdir);
1722 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1725 newfdp->fd_jdir = fdp->fd_jdir;
1726 vref(newfdp->fd_jdir);
1727 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1729 spin_unlock(&fdp->fd_spin);
1731 /* Create the file descriptor table. */
1732 newfdp->fd_refcnt = 1;
1733 newfdp->fd_cmask = cmask;
1734 newfdp->fd_files = newfdp->fd_builtin_files;
1735 newfdp->fd_nfiles = NDFILE;
1736 newfdp->fd_lastfile = -1;
1737 spin_init(&newfdp->fd_spin);
1743 * Share a filedesc structure.
1748 fdshare(struct proc *p)
1750 struct filedesc *fdp;
1753 spin_lock(&fdp->fd_spin);
1755 spin_unlock(&fdp->fd_spin);
1760 * Copy a filedesc structure.
1765 fdcopy(struct proc *p)
1767 struct filedesc *fdp = p->p_fd;
1768 struct filedesc *newfdp;
1769 struct fdnode *fdnode;
1774 * Certain daemons might not have file descriptors.
1780 * Allocate the new filedesc and fd_files[] array. This can race
1781 * with operations by other threads on the fdp so we have to be
1784 newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO);
1786 spin_lock(&fdp->fd_spin);
1787 if (fdp->fd_lastfile < NDFILE) {
1788 newfdp->fd_files = newfdp->fd_builtin_files;
1792 * We have to allocate (N^2-1) entries for our in-place
1793 * binary tree. Allow the table to shrink.
1797 while (ni > fdp->fd_lastfile && ni > NDFILE) {
1801 spin_unlock(&fdp->fd_spin);
1802 newfdp->fd_files = kmalloc(i * sizeof(struct fdnode),
1803 M_FILEDESC, M_WAITOK | M_ZERO);
1806 * Check for race, retry
1808 spin_lock(&fdp->fd_spin);
1809 if (i <= fdp->fd_lastfile) {
1810 spin_unlock(&fdp->fd_spin);
1811 kfree(newfdp->fd_files, M_FILEDESC);
1817 * Dup the remaining fields. vref() and cache_hold() can be
1818 * safely called while holding the read spinlock on fdp.
1820 * The read spinlock on fdp is still being held.
1822 * NOTE: vref and cache_hold calls for the case where the vnode
1823 * or cache entry already has at least one ref may be called
1824 * while holding spin locks.
1826 if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) {
1827 vref(newfdp->fd_cdir);
1828 cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir);
1831 * We must check for fd_rdir here, at least for now because
1832 * the init process is created before we have access to the
1833 * rootvode to take a reference to it.
1835 if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) {
1836 vref(newfdp->fd_rdir);
1837 cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir);
1839 if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) {
1840 vref(newfdp->fd_jdir);
1841 cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir);
1843 newfdp->fd_refcnt = 1;
1844 newfdp->fd_nfiles = i;
1845 newfdp->fd_lastfile = fdp->fd_lastfile;
1846 newfdp->fd_freefile = fdp->fd_freefile;
1847 newfdp->fd_cmask = fdp->fd_cmask;
1848 spin_init(&newfdp->fd_spin);
1851 * Copy the descriptor table through (i). This also copies the
1852 * allocation state. Then go through and ref the file pointers
1853 * and clean up any KQ descriptors.
1855 * kq descriptors cannot be copied. Since we haven't ref'd the
1856 * copied files yet we can ignore the return value from funsetfd().
1858 * The read spinlock on fdp is still being held.
1860 bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode));
1861 for (i = 0 ; i < newfdp->fd_nfiles; ++i) {
1862 fdnode = &newfdp->fd_files[i];
1863 if (fdnode->reserved) {
1864 fdreserve_locked(newfdp, i, -1);
1865 fdnode->reserved = 0;
1866 fdfixup_locked(newfdp, i);
1867 } else if (fdnode->fp) {
1868 if (fdnode->fp->f_type == DTYPE_KQUEUE) {
1869 (void)funsetfd_locked(newfdp, i);
1875 spin_unlock(&fdp->fd_spin);
1880 * Release a filedesc structure.
1882 * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE)
1885 fdfree(struct proc *p, struct filedesc *repl)
1887 struct filedesc *fdp;
1888 struct fdnode *fdnode;
1890 struct filedesc_to_leader *fdtol;
1896 * Certain daemons might not have file descriptors.
1905 * Severe messing around to follow.
1907 spin_lock(&fdp->fd_spin);
1909 /* Check for special need to clear POSIX style locks */
1911 if (fdtol != NULL) {
1912 KASSERT(fdtol->fdl_refcount > 0,
1913 ("filedesc_to_refcount botch: fdl_refcount=%d",
1914 fdtol->fdl_refcount));
1915 if (fdtol->fdl_refcount == 1 &&
1916 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1917 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1918 fdnode = &fdp->fd_files[i];
1919 if (fdnode->fp == NULL ||
1920 fdnode->fp->f_type != DTYPE_VNODE) {
1925 spin_unlock(&fdp->fd_spin);
1927 lf.l_whence = SEEK_SET;
1930 lf.l_type = F_UNLCK;
1931 vp = (struct vnode *)fp->f_data;
1932 (void) VOP_ADVLOCK(vp,
1933 (caddr_t)p->p_leader,
1938 spin_lock(&fdp->fd_spin);
1942 if (fdtol->fdl_refcount == 1) {
1943 if (fdp->fd_holdleaderscount > 0 &&
1944 (p->p_leader->p_flag & P_ADVLOCK) != 0) {
1946 * close() or do_dup() has cleared a reference
1947 * in a shared file descriptor table.
1949 fdp->fd_holdleaderswakeup = 1;
1950 ssleep(&fdp->fd_holdleaderscount,
1951 &fdp->fd_spin, 0, "fdlhold", 0);
1954 if (fdtol->fdl_holdcount > 0) {
1956 * Ensure that fdtol->fdl_leader
1957 * remains valid in closef().
1959 fdtol->fdl_wakeup = 1;
1960 ssleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0);
1964 fdtol->fdl_refcount--;
1965 if (fdtol->fdl_refcount == 0 &&
1966 fdtol->fdl_holdcount == 0) {
1967 fdtol->fdl_next->fdl_prev = fdtol->fdl_prev;
1968 fdtol->fdl_prev->fdl_next = fdtol->fdl_next;
1973 if (fdtol != NULL) {
1974 spin_unlock(&fdp->fd_spin);
1975 kfree(fdtol, M_FILEDESC_TO_LEADER);
1976 spin_lock(&fdp->fd_spin);
1979 if (--fdp->fd_refcnt > 0) {
1980 spin_unlock(&fdp->fd_spin);
1981 spin_lock(&p->p_spin);
1983 spin_unlock(&p->p_spin);
1988 * Even though we are the last reference to the structure allproc
1989 * scans may still reference the structure. Maintain proper
1990 * locks until we can replace p->p_fd.
1992 * Also note that kqueue's closef still needs to reference the
1993 * fdp via p->p_fd, so we have to close the descriptors before
1994 * we replace p->p_fd.
1996 for (i = 0; i <= fdp->fd_lastfile; ++i) {
1997 if (fdp->fd_files[i].fp) {
1998 fp = funsetfd_locked(fdp, i);
2000 spin_unlock(&fdp->fd_spin);
2001 if (SLIST_FIRST(&fp->f_klist))
2002 knote_fdclose(fp, fdp, i);
2004 spin_lock(&fdp->fd_spin);
2008 spin_unlock(&fdp->fd_spin);
2011 * Interlock against an allproc scan operations (typically frevoke).
2013 spin_lock(&p->p_spin);
2015 spin_unlock(&p->p_spin);
2018 * Wait for any softrefs to go away. This race rarely occurs so
2019 * we can use a non-critical-path style poll/sleep loop. The
2020 * race only occurs against allproc scans.
2022 * No new softrefs can occur with the fdp disconnected from the
2025 if (fdp->fd_softrefs) {
2026 kprintf("pid %d: Warning, fdp race avoided\n", p->p_pid);
2027 while (fdp->fd_softrefs)
2028 tsleep(&fdp->fd_softrefs, 0, "fdsoft", 1);
2031 if (fdp->fd_files != fdp->fd_builtin_files)
2032 kfree(fdp->fd_files, M_FILEDESC);
2034 cache_drop(&fdp->fd_ncdir);
2035 vrele(fdp->fd_cdir);
2038 cache_drop(&fdp->fd_nrdir);
2039 vrele(fdp->fd_rdir);
2042 cache_drop(&fdp->fd_njdir);
2043 vrele(fdp->fd_jdir);
2045 kfree(fdp, M_FILEDESC);
2049 * Retrieve and reference the file pointer associated with a descriptor.
2054 holdfp(struct filedesc *fdp, int fd, int flag)
2058 spin_lock(&fdp->fd_spin);
2059 if (((u_int)fd) >= fdp->fd_nfiles) {
2063 if ((fp = fdp->fd_files[fd].fp) == NULL)
2065 if ((fp->f_flag & flag) == 0 && flag != -1) {
2071 spin_unlock(&fdp->fd_spin);
2076 * holdsock() - load the struct file pointer associated
2077 * with a socket into *fpp. If an error occurs, non-zero
2078 * will be returned and *fpp will be set to NULL.
2083 holdsock(struct filedesc *fdp, int fd, struct file **fpp)
2088 spin_lock(&fdp->fd_spin);
2089 if ((unsigned)fd >= fdp->fd_nfiles) {
2094 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2098 if (fp->f_type != DTYPE_SOCKET) {
2105 spin_unlock(&fdp->fd_spin);
2111 * Convert a user file descriptor to a held file pointer.
2116 holdvnode(struct filedesc *fdp, int fd, struct file **fpp)
2121 spin_lock(&fdp->fd_spin);
2122 if ((unsigned)fd >= fdp->fd_nfiles) {
2127 if ((fp = fdp->fd_files[fd].fp) == NULL) {
2131 if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) {
2139 spin_unlock(&fdp->fd_spin);
2145 * For setugid programs, we don't want to people to use that setugidness
2146 * to generate error messages which write to a file which otherwise would
2147 * otherwise be off-limits to the process.
2149 * This is a gross hack to plug the hole. A better solution would involve
2150 * a special vop or other form of generalized access control mechanism. We
2151 * go ahead and just reject all procfs file systems accesses as dangerous.
2153 * Since setugidsafety calls this only for fd 0, 1 and 2, this check is
2154 * sufficient. We also don't for check setugidness since we know we are.
2157 is_unsafe(struct file *fp)
2159 if (fp->f_type == DTYPE_VNODE &&
2160 ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS)
2166 * Make this setguid thing safe, if at all possible.
2168 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2171 setugidsafety(struct proc *p)
2173 struct filedesc *fdp = p->p_fd;
2176 /* Certain daemons might not have file descriptors. */
2181 * note: fdp->fd_files may be reallocated out from under us while
2182 * we are blocked in a close. Be careful!
2184 for (i = 0; i <= fdp->fd_lastfile; i++) {
2187 if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) {
2191 * NULL-out descriptor prior to close to avoid
2192 * a race while close blocks.
2194 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2195 knote_fdclose(fp, fdp, i);
2203 * Close any files on exec?
2205 * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose()
2208 fdcloseexec(struct proc *p)
2210 struct filedesc *fdp = p->p_fd;
2213 /* Certain daemons might not have file descriptors. */
2218 * We cannot cache fd_files since operations may block and rip
2219 * them out from under us.
2221 for (i = 0; i <= fdp->fd_lastfile; i++) {
2222 if (fdp->fd_files[i].fp != NULL &&
2223 (fdp->fd_files[i].fileflags & UF_EXCLOSE)) {
2227 * NULL-out descriptor prior to close to avoid
2228 * a race while close blocks.
2230 if ((fp = funsetfd_locked(fdp, i)) != NULL) {
2231 knote_fdclose(fp, fdp, i);
2239 * It is unsafe for set[ug]id processes to be started with file
2240 * descriptors 0..2 closed, as these descriptors are given implicit
2241 * significance in the Standard C library. fdcheckstd() will create a
2242 * descriptor referencing /dev/null for each of stdin, stdout, and
2243 * stderr that is not already open.
2245 * NOT MPSAFE - calls falloc, vn_open, etc
2248 fdcheckstd(struct lwp *lp)
2250 struct nlookupdata nd;
2251 struct filedesc *fdp;
2254 int i, error, flags, devnull;
2256 fdp = lp->lwp_proc->p_fd;
2261 for (i = 0; i < 3; i++) {
2262 if (fdp->fd_files[i].fp != NULL)
2265 if ((error = falloc(lp, &fp, &devnull)) != 0)
2268 error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE,
2269 NLC_FOLLOW|NLC_LOCKVP);
2270 flags = FREAD | FWRITE;
2272 error = vn_open(&nd, fp, flags, 0);
2274 fsetfd(fdp, fp, devnull);
2276 fsetfd(fdp, NULL, devnull);
2281 KKASSERT(i == devnull);
2283 error = kern_dup(DUP_FIXED, devnull, i, &retval);
2292 * Internal form of close.
2293 * Decrement reference count on file structure.
2294 * Note: td and/or p may be NULL when closing a file
2295 * that was being passed in a message.
2297 * MPALMOSTSAFE - acquires mplock for VOP operations
2300 closef(struct file *fp, struct proc *p)
2304 struct filedesc_to_leader *fdtol;
2310 * POSIX record locking dictates that any close releases ALL
2311 * locks owned by this process. This is handled by setting
2312 * a flag in the unlock to free ONLY locks obeying POSIX
2313 * semantics, and not to free BSD-style file locks.
2314 * If the descriptor was in a message, POSIX-style locks
2315 * aren't passed with the descriptor.
2317 if (p != NULL && fp->f_type == DTYPE_VNODE &&
2318 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2321 if ((p->p_leader->p_flag & P_ADVLOCK) != 0) {
2322 lf.l_whence = SEEK_SET;
2325 lf.l_type = F_UNLCK;
2326 vp = (struct vnode *)fp->f_data;
2327 (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK,
2331 if (fdtol != NULL) {
2333 * Handle special case where file descriptor table
2334 * is shared between multiple process leaders.
2336 for (fdtol = fdtol->fdl_next;
2337 fdtol != p->p_fdtol;
2338 fdtol = fdtol->fdl_next) {
2339 if ((fdtol->fdl_leader->p_flag &
2342 fdtol->fdl_holdcount++;
2343 lf.l_whence = SEEK_SET;
2346 lf.l_type = F_UNLCK;
2347 vp = (struct vnode *)fp->f_data;
2348 (void) VOP_ADVLOCK(vp,
2349 (caddr_t)fdtol->fdl_leader,
2350 F_UNLCK, &lf, F_POSIX);
2351 fdtol->fdl_holdcount--;
2352 if (fdtol->fdl_holdcount == 0 &&
2353 fdtol->fdl_wakeup != 0) {
2354 fdtol->fdl_wakeup = 0;
2367 * fhold() can only be called if f_count is already at least 1 (i.e. the
2368 * caller of fhold() already has a reference to the file pointer in some
2371 * f_count is not spin-locked. Instead, atomic ops are used for
2372 * incrementing, decrementing, and handling the 1->0 transition.
2375 fhold(struct file *fp)
2377 atomic_add_int(&fp->f_count, 1);
2381 * fdrop() - drop a reference to a descriptor
2383 * MPALMOSTSAFE - acquires mplock for final close sequence
2386 fdrop(struct file *fp)
2393 * A combined fetch and subtract is needed to properly detect
2394 * 1->0 transitions, otherwise two cpus dropping from a ref
2395 * count of 2 might both try to run the 1->0 code.
2397 if (atomic_fetchadd_int(&fp->f_count, -1) > 1)
2400 KKASSERT(SLIST_FIRST(&fp->f_klist) == NULL);
2404 * The last reference has gone away, we own the fp structure free
2407 if (fp->f_count < 0)
2408 panic("fdrop: count < 0");
2409 if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE &&
2410 (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS)
2412 lf.l_whence = SEEK_SET;
2415 lf.l_type = F_UNLCK;
2416 vp = (struct vnode *)fp->f_data;
2417 (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2419 if (fp->f_ops != &badfileops)
2420 error = fo_close(fp);
2429 * Apply an advisory lock on a file descriptor.
2431 * Just attempt to get a record lock of the requested type on
2432 * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0).
2437 sys_flock(struct flock_args *uap)
2439 struct proc *p = curproc;
2445 if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL)
2448 if (fp->f_type != DTYPE_VNODE) {
2452 vp = (struct vnode *)fp->f_data;
2453 lf.l_whence = SEEK_SET;
2456 if (uap->how & LOCK_UN) {
2457 lf.l_type = F_UNLCK;
2458 fp->f_flag &= ~FHASLOCK;
2459 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0);
2462 if (uap->how & LOCK_EX)
2463 lf.l_type = F_WRLCK;
2464 else if (uap->how & LOCK_SH)
2465 lf.l_type = F_RDLCK;
2470 fp->f_flag |= FHASLOCK;
2471 if (uap->how & LOCK_NB)
2472 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0);
2474 error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT);
2482 * File Descriptor pseudo-device driver (/dev/fd/).
2484 * Opening minor device N dup()s the file (if any) connected to file
2485 * descriptor N belonging to the calling process. Note that this driver
2486 * consists of only the ``open()'' routine, because all subsequent
2487 * references to this file will be direct to the other driver.
2490 fdopen(struct dev_open_args *ap)
2492 thread_t td = curthread;
2494 KKASSERT(td->td_lwp != NULL);
2497 * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the
2498 * the file descriptor being sought for duplication. The error
2499 * return ensures that the vnode for this device will be released
2500 * by vn_open. Open will detect this special error and take the
2501 * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN
2502 * will simply report the error.
2504 td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev);
2509 * The caller has reserved the file descriptor dfd for us. On success we
2510 * must fsetfd() it. On failure the caller will clean it up.
2515 dupfdopen(struct filedesc *fdp, int dfd, int sfd, int mode, int error)
2521 if ((wfp = holdfp(fdp, sfd, -1)) == NULL)
2525 * Close a revoke/dup race. Duping a descriptor marked as revoked
2526 * will dup a dummy descriptor instead of the real one.
2528 if (wfp->f_flag & FREVOKED) {
2529 kprintf("Warning: attempt to dup() a revoked descriptor\n");
2532 werror = falloc(NULL, &wfp, NULL);
2538 * There are two cases of interest here.
2540 * For ENODEV simply dup sfd to file descriptor dfd and return.
2542 * For ENXIO steal away the file structure from sfd and store it
2543 * dfd. sfd is effectively closed by this operation.
2545 * Any other error code is just returned.
2550 * Check that the mode the file is being opened for is a
2551 * subset of the mode of the existing descriptor.
2553 if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
2557 spin_lock(&fdp->fd_spin);
2558 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2559 fsetfd_locked(fdp, wfp, dfd);
2560 spin_unlock(&fdp->fd_spin);
2565 * Steal away the file pointer from dfd, and stuff it into indx.
2567 spin_lock(&fdp->fd_spin);
2568 fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags;
2569 fsetfd(fdp, wfp, dfd);
2570 if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) {
2571 spin_unlock(&fdp->fd_spin);
2574 spin_unlock(&fdp->fd_spin);
2586 * NOT MPSAFE - I think these refer to a common file descriptor table
2587 * and we need to spinlock that to link fdtol in.
2589 struct filedesc_to_leader *
2590 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
2591 struct proc *leader)
2593 struct filedesc_to_leader *fdtol;
2595 fdtol = kmalloc(sizeof(struct filedesc_to_leader),
2596 M_FILEDESC_TO_LEADER, M_WAITOK);
2597 fdtol->fdl_refcount = 1;
2598 fdtol->fdl_holdcount = 0;
2599 fdtol->fdl_wakeup = 0;
2600 fdtol->fdl_leader = leader;
2602 fdtol->fdl_next = old->fdl_next;
2603 fdtol->fdl_prev = old;
2604 old->fdl_next = fdtol;
2605 fdtol->fdl_next->fdl_prev = fdtol;
2607 fdtol->fdl_next = fdtol;
2608 fdtol->fdl_prev = fdtol;
2614 * Scan all file pointers in the system. The callback is made with
2615 * the master list spinlock held exclusively.
2620 allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data)
2625 spin_lock(&filehead_spin);
2626 LIST_FOREACH(fp, &filehead, f_list) {
2627 res = callback(fp, data);
2631 spin_unlock(&filehead_spin);
2635 * Get file structures.
2637 * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe)
2640 struct sysctl_kern_file_info {
2643 struct sysctl_req *req;
2646 static int sysctl_kern_file_callback(struct proc *p, void *data);
2649 sysctl_kern_file(SYSCTL_HANDLER_ARGS)
2651 struct sysctl_kern_file_info info;
2654 * Note: because the number of file descriptors is calculated
2655 * in different ways for sizing vs returning the data,
2656 * there is information leakage from the first loop. However,
2657 * it is of a similar order of magnitude to the leakage from
2658 * global system statistics such as kern.openfiles.
2660 * When just doing a count, note that we cannot just count
2661 * the elements and add f_count via the filehead list because
2662 * threaded processes share their descriptor table and f_count might
2663 * still be '1' in that case.
2665 * Since the SYSCTL op can block, we must hold the process to
2666 * prevent it being ripped out from under us either in the
2667 * file descriptor loop or in the greater LIST_FOREACH. The
2668 * process may be in varying states of disrepair. If the process
2669 * is in SZOMB we may have caught it just as it is being removed
2670 * from the allproc list, we must skip it in that case to maintain
2671 * an unbroken chain through the allproc list.
2676 allproc_scan(sysctl_kern_file_callback, &info);
2679 * When just calculating the size, overestimate a bit to try to
2680 * prevent system activity from causing the buffer-fill call
2683 if (req->oldptr == NULL) {
2684 info.count = (info.count + 16) + (info.count / 10);
2685 info.error = SYSCTL_OUT(req, NULL,
2686 info.count * sizeof(struct kinfo_file));
2688 return (info.error);
2692 sysctl_kern_file_callback(struct proc *p, void *data)
2694 struct sysctl_kern_file_info *info = data;
2695 struct kinfo_file kf;
2696 struct filedesc *fdp;
2701 if (p->p_stat == SIDL || p->p_stat == SZOMB)
2703 if (!PRISON_CHECK(info->req->td->td_ucred, p->p_ucred) != 0)
2707 * Softref the fdp to prevent it from being destroyed
2709 spin_lock(&p->p_spin);
2710 if ((fdp = p->p_fd) == NULL) {
2711 spin_unlock(&p->p_spin);
2714 atomic_add_int(&fdp->fd_softrefs, 1);
2715 spin_unlock(&p->p_spin);
2718 * The fdp's own spinlock prevents the contents from being
2721 spin_lock(&fdp->fd_spin);
2722 for (n = 0; n < fdp->fd_nfiles; ++n) {
2723 if ((fp = fdp->fd_files[n].fp) == NULL)
2725 if (info->req->oldptr == NULL) {
2728 uid = p->p_ucred ? p->p_ucred->cr_uid : -1;
2729 kcore_make_file(&kf, fp, p->p_pid, uid, n);
2730 spin_unlock(&fdp->fd_spin);
2731 info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf));
2732 spin_lock(&fdp->fd_spin);
2737 spin_unlock(&fdp->fd_spin);
2738 atomic_subtract_int(&fdp->fd_softrefs, 1);
2744 SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD,
2745 0, 0, sysctl_kern_file, "S,file", "Entire file table");
2747 SYSCTL_INT(_kern, OID_AUTO, minfilesperproc, CTLFLAG_RW,
2748 &minfilesperproc, 0, "Minimum files allowed open per process");
2749 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
2750 &maxfilesperproc, 0, "Maximum files allowed open per process");
2751 SYSCTL_INT(_kern, OID_AUTO, maxfilesperuser, CTLFLAG_RW,
2752 &maxfilesperuser, 0, "Maximum files allowed open per user");
2754 SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
2755 &maxfiles, 0, "Maximum number of files");
2757 SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW,
2758 &maxfilesrootres, 0, "Descriptors reserved for root use");
2760 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
2761 &nfiles, 0, "System-wide number of open files");
2764 fildesc_drvinit(void *unused)
2768 for (fd = 0; fd < NUMFDESC; fd++) {
2769 make_dev(&fildesc_ops, fd,
2770 UID_BIN, GID_BIN, 0666, "fd/%d", fd);
2773 make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin");
2774 make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout");
2775 make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr");
2781 struct fileops badfileops = {
2782 .fo_read = badfo_readwrite,
2783 .fo_write = badfo_readwrite,
2784 .fo_ioctl = badfo_ioctl,
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 * Must return an error to prevent registration, typically
2810 * due to a revoked descriptor (file_filtops assigned).
2813 badfo_kqfilter(struct file *fp, struct knote *kn)
2815 return (EOPNOTSUPP);
2822 badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred)
2831 badfo_close(struct file *fp)
2840 badfo_shutdown(struct file *fp, int how)
2849 nofo_shutdown(struct file *fp, int how)
2851 return (EOPNOTSUPP);
2854 SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,
2855 fildesc_drvinit,NULL)