/* $NetBSD: kern_descrip.c,v 1.265 2024/12/21 19:02:31 riastradh Exp $ */ /*- * Copyright (c) 2008, 2009, 2023 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Andrew Doran. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1982, 1986, 1989, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_descrip.c 8.8 (Berkeley) 2/14/95 */ /* * File descriptor management. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_descrip.c,v 1.265 2024/12/21 19:02:31 riastradh Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * A list (head) of open files, counter, and lock protecting them. */ struct filelist filehead __cacheline_aligned; static u_int nfiles __cacheline_aligned; kmutex_t filelist_lock __cacheline_aligned; static pool_cache_t filedesc_cache __read_mostly; static pool_cache_t file_cache __read_mostly; static int file_ctor(void *, void *, int); static void file_dtor(void *, void *); static void fdfile_ctor(fdfile_t *); static void fdfile_dtor(fdfile_t *); static int filedesc_ctor(void *, void *, int); static void filedesc_dtor(void *, void *); static int filedescopen(dev_t, int, int, lwp_t *); static int sysctl_kern_file(SYSCTLFN_PROTO); static int sysctl_kern_file2(SYSCTLFN_PROTO); static void fill_file(struct file *, const struct file *); static void fill_file2(struct kinfo_file *, const file_t *, const fdfile_t *, int, pid_t); const struct cdevsw filedesc_cdevsw = { .d_open = filedescopen, .d_close = noclose, .d_read = noread, .d_write = nowrite, .d_ioctl = noioctl, .d_stop = nostop, .d_tty = notty, .d_poll = nopoll, .d_mmap = nommap, .d_kqfilter = nokqfilter, .d_discard = nodiscard, .d_flag = D_OTHER | D_MPSAFE }; /* For ease of reading. */ __strong_alias(fd_putvnode,fd_putfile) __strong_alias(fd_putsock,fd_putfile) /* * Initialize the descriptor system. */ void fd_sys_init(void) { static struct sysctllog *clog; mutex_init(&filelist_lock, MUTEX_DEFAULT, IPL_NONE); LIST_INIT(&filehead); file_cache = pool_cache_init(sizeof(file_t), coherency_unit, 0, 0, "file", NULL, IPL_NONE, file_ctor, file_dtor, NULL); KASSERT(file_cache != NULL); filedesc_cache = pool_cache_init(sizeof(filedesc_t), coherency_unit, 0, 0, "filedesc", NULL, IPL_NONE, filedesc_ctor, filedesc_dtor, NULL); KASSERT(filedesc_cache != NULL); sysctl_createv(&clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_STRUCT, "file", SYSCTL_DESCR("System open file table"), sysctl_kern_file, 0, NULL, 0, CTL_KERN, KERN_FILE, CTL_EOL); sysctl_createv(&clog, 0, NULL, NULL, CTLFLAG_PERMANENT, CTLTYPE_STRUCT, "file2", SYSCTL_DESCR("System open file table"), sysctl_kern_file2, 0, NULL, 0, CTL_KERN, KERN_FILE2, CTL_EOL); } static bool fd_isused(filedesc_t *fdp, unsigned fd) { u_int off = fd >> NDENTRYSHIFT; KASSERT(fd < atomic_load_consume(&fdp->fd_dt)->dt_nfiles); return (fdp->fd_lomap[off] & (1U << (fd & NDENTRYMASK))) != 0; } /* * Verify that the bitmaps match the descriptor table. */ static inline void fd_checkmaps(filedesc_t *fdp) { #ifdef DEBUG fdtab_t *dt; u_int fd; KASSERT(fdp->fd_refcnt <= 1 || mutex_owned(&fdp->fd_lock)); dt = fdp->fd_dt; if (fdp->fd_refcnt == -1) { /* * fd_free tears down the table without maintaining its bitmap. */ return; } for (fd = 0; fd < dt->dt_nfiles; fd++) { if (fd < NDFDFILE) { KASSERT(dt->dt_ff[fd] == (fdfile_t *)fdp->fd_dfdfile[fd]); } if (dt->dt_ff[fd] == NULL) { KASSERT(!fd_isused(fdp, fd)); } else if (dt->dt_ff[fd]->ff_file != NULL) { KASSERT(fd_isused(fdp, fd)); } } #endif } static int fd_next_zero(filedesc_t *fdp, uint32_t *bitmap, int want, u_int bits) { int i, off, maxoff; uint32_t sub; KASSERT(mutex_owned(&fdp->fd_lock)); fd_checkmaps(fdp); if (want > bits) return -1; off = want >> NDENTRYSHIFT; i = want & NDENTRYMASK; if (i) { sub = bitmap[off] | ((u_int)~0 >> (NDENTRIES - i)); if (sub != ~0) goto found; off++; } maxoff = NDLOSLOTS(bits); while (off < maxoff) { if ((sub = bitmap[off]) != ~0) goto found; off++; } return -1; found: return (off << NDENTRYSHIFT) + ffs(~sub) - 1; } static int fd_last_set(filedesc_t *fd, int last) { int off, i; fdfile_t **ff = fd->fd_dt->dt_ff; uint32_t *bitmap = fd->fd_lomap; KASSERT(mutex_owned(&fd->fd_lock)); fd_checkmaps(fd); off = (last - 1) >> NDENTRYSHIFT; while (off >= 0 && !bitmap[off]) off--; if (off < 0) return -1; i = ((off + 1) << NDENTRYSHIFT) - 1; if (i >= last) i = last - 1; /* XXX should use bitmap */ while (i > 0 && (ff[i] == NULL || !ff[i]->ff_allocated)) i--; return i; } static inline void fd_used(filedesc_t *fdp, unsigned fd) { u_int off = fd >> NDENTRYSHIFT; fdfile_t *ff; ff = fdp->fd_dt->dt_ff[fd]; KASSERT(mutex_owned(&fdp->fd_lock)); KASSERT((fdp->fd_lomap[off] & (1U << (fd & NDENTRYMASK))) == 0); KASSERT(ff != NULL); KASSERT(ff->ff_file == NULL); KASSERT(!ff->ff_allocated); ff->ff_allocated = true; fdp->fd_lomap[off] |= 1U << (fd & NDENTRYMASK); if (__predict_false(fdp->fd_lomap[off] == ~0)) { KASSERT((fdp->fd_himap[off >> NDENTRYSHIFT] & (1U << (off & NDENTRYMASK))) == 0); fdp->fd_himap[off >> NDENTRYSHIFT] |= 1U << (off & NDENTRYMASK); } if ((int)fd > fdp->fd_lastfile) { fdp->fd_lastfile = fd; } fd_checkmaps(fdp); } static inline void fd_unused(filedesc_t *fdp, unsigned fd) { u_int off = fd >> NDENTRYSHIFT; fdfile_t *ff; ff = fdp->fd_dt->dt_ff[fd]; KASSERT(mutex_owned(&fdp->fd_lock)); KASSERT(ff != NULL); KASSERT(ff->ff_file == NULL); KASSERT(ff->ff_allocated); if (fd < fdp->fd_freefile) { fdp->fd_freefile = fd; } if (fdp->fd_lomap[off] == ~0) { KASSERT((fdp->fd_himap[off >> NDENTRYSHIFT] & (1U << (off & NDENTRYMASK))) != 0); fdp->fd_himap[off >> NDENTRYSHIFT] &= ~(1U << (off & NDENTRYMASK)); } KASSERT((fdp->fd_lomap[off] & (1U << (fd & NDENTRYMASK))) != 0); fdp->fd_lomap[off] &= ~(1U << (fd & NDENTRYMASK)); ff->ff_allocated = false; KASSERT(fd <= fdp->fd_lastfile); if (fd == fdp->fd_lastfile) { fdp->fd_lastfile = fd_last_set(fdp, fd); } fd_checkmaps(fdp); } /* * Look up the file structure corresponding to a file descriptor * and return the file, holding a reference on the descriptor. */ file_t * fd_getfile(unsigned fd) { filedesc_t *fdp; fdfile_t *ff; file_t *fp; fdtab_t *dt; /* * Look up the fdfile structure representing this descriptor. * We are doing this unlocked. See fd_tryexpand(). */ fdp = curlwp->l_fd; dt = atomic_load_consume(&fdp->fd_dt); if (__predict_false(fd >= dt->dt_nfiles)) { return NULL; } ff = dt->dt_ff[fd]; KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); if (__predict_false(ff == NULL)) { return NULL; } /* Now get a reference to the descriptor. */ if (fdp->fd_refcnt == 1) { /* * Single threaded: don't need to worry about concurrent * access (other than earlier calls to kqueue, which may * hold a reference to the descriptor). */ ff->ff_refcnt++; } else { /* * Multi threaded: issue a memory barrier to ensure that we * acquire the file pointer _after_ adding a reference. If * no memory barrier, we could fetch a stale pointer. * * In particular, we must coordinate the following four * memory operations: * * A. fd_close store ff->ff_file = NULL * B. fd_close refcnt = atomic_dec_uint_nv(&ff->ff_refcnt) * C. fd_getfile atomic_inc_uint(&ff->ff_refcnt) * D. fd_getfile load fp = ff->ff_file * * If the order is D;A;B;C: * * 1. D: fp = ff->ff_file * 2. A: ff->ff_file = NULL * 3. B: refcnt = atomic_dec_uint_nv(&ff->ff_refcnt) * 4. C: atomic_inc_uint(&ff->ff_refcnt) * * then fd_close determines that there are no more * references and decides to free fp immediately, at * the same that fd_getfile ends up with an fp that's * about to be freed. *boom* * * By making B a release operation in fd_close, and by * making C an acquire operation in fd_getfile, since * they are atomic operations on the same object, which * has a total modification order, we guarantee either: * * - B happens before C. Then since A is * sequenced before B in fd_close, and C is * sequenced before D in fd_getfile, we * guarantee A happens before D, so fd_getfile * reads a null fp and safely fails. * * - C happens before B. Then fd_getfile may read * null or nonnull, but either way, fd_close * will safely wait for references to drain. */ atomic_inc_uint(&ff->ff_refcnt); membar_acquire(); } /* * If the file is not open or is being closed then put the * reference back. */ fp = atomic_load_consume(&ff->ff_file); if (__predict_true(fp != NULL)) { return fp; } fd_putfile(fd); return NULL; } /* * Release a reference to a file descriptor acquired with fd_getfile(). */ void fd_putfile(unsigned fd) { filedesc_t *fdp; fdfile_t *ff; u_int u, v; fdp = curlwp->l_fd; KASSERT(fd < atomic_load_consume(&fdp->fd_dt)->dt_nfiles); ff = atomic_load_consume(&fdp->fd_dt)->dt_ff[fd]; KASSERT(ff != NULL); KASSERT((ff->ff_refcnt & FR_MASK) > 0); KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); if (fdp->fd_refcnt == 1) { /* * Single threaded: don't need to worry about concurrent * access (other than earlier calls to kqueue, which may * hold a reference to the descriptor). */ if (__predict_false((ff->ff_refcnt & FR_CLOSING) != 0)) { fd_close(fd); return; } ff->ff_refcnt--; return; } /* * Ensure that any use of the file is complete and globally * visible before dropping the final reference. If no membar, * the current CPU could still access memory associated with * the file after it has been freed or recycled by another * CPU. */ membar_release(); /* * Be optimistic and start out with the assumption that no other * threads are trying to close the descriptor. If the CAS fails, * we lost a race and/or it's being closed. */ for (u = ff->ff_refcnt & FR_MASK;; u = v) { v = atomic_cas_uint(&ff->ff_refcnt, u, u - 1); if (__predict_true(u == v)) { return; } if (__predict_false((v & FR_CLOSING) != 0)) { break; } } /* Another thread is waiting to close the file: join it. */ (void)fd_close(fd); } /* * Convenience wrapper around fd_getfile() that returns reference * to a vnode. */ int fd_getvnode(unsigned fd, file_t **fpp) { vnode_t *vp; file_t *fp; fp = fd_getfile(fd); if (__predict_false(fp == NULL)) { return EBADF; } if (__predict_false(fp->f_type != DTYPE_VNODE)) { fd_putfile(fd); return EINVAL; } vp = fp->f_vnode; if (__predict_false(vp->v_type == VBAD)) { /* XXX Is this case really necessary? */ fd_putfile(fd); return EBADF; } *fpp = fp; return 0; } /* * Convenience wrapper around fd_getfile() that returns reference * to a socket. */ int fd_getsock1(unsigned fd, struct socket **sop, file_t **fp) { *fp = fd_getfile(fd); if (__predict_false(*fp == NULL)) { return EBADF; } if (__predict_false((*fp)->f_type != DTYPE_SOCKET)) { fd_putfile(fd); return ENOTSOCK; } *sop = (*fp)->f_socket; return 0; } int fd_getsock(unsigned fd, struct socket **sop) { file_t *fp; return fd_getsock1(fd, sop, &fp); } /* * Look up the file structure corresponding to a file descriptor * and return it with a reference held on the file, not the * descriptor. * * This is heavyweight and only used when accessing descriptors * from a foreign process. The caller must ensure that `p' does * not exit or fork across this call. * * To release the file (not descriptor) reference, use closef(). */ file_t * fd_getfile2(proc_t *p, unsigned fd) { filedesc_t *fdp; fdfile_t *ff; file_t *fp; fdtab_t *dt; fdp = p->p_fd; mutex_enter(&fdp->fd_lock); dt = fdp->fd_dt; if (fd >= dt->dt_nfiles) { mutex_exit(&fdp->fd_lock); return NULL; } if ((ff = dt->dt_ff[fd]) == NULL) { mutex_exit(&fdp->fd_lock); return NULL; } if ((fp = atomic_load_consume(&ff->ff_file)) == NULL) { mutex_exit(&fdp->fd_lock); return NULL; } mutex_enter(&fp->f_lock); fp->f_count++; mutex_exit(&fp->f_lock); mutex_exit(&fdp->fd_lock); return fp; } /* * Internal form of close. Must be called with a reference to the * descriptor, and will drop the reference. When all descriptor * references are dropped, releases the descriptor slot and a single * reference to the file structure. */ int fd_close(unsigned fd) { struct flock lf; filedesc_t *fdp; fdfile_t *ff; file_t *fp; proc_t *p; lwp_t *l; u_int refcnt; l = curlwp; p = l->l_proc; fdp = l->l_fd; ff = atomic_load_consume(&fdp->fd_dt)->dt_ff[fd]; KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); mutex_enter(&fdp->fd_lock); KASSERT((ff->ff_refcnt & FR_MASK) > 0); fp = atomic_load_consume(&ff->ff_file); if (__predict_false(fp == NULL)) { /* * Another user of the file is already closing, and is * waiting for other users of the file to drain. Release * our reference, and wake up the closer. */ membar_release(); atomic_dec_uint(&ff->ff_refcnt); cv_broadcast(&ff->ff_closing); mutex_exit(&fdp->fd_lock); /* * An application error, so pretend that the descriptor * was already closed. We can't safely wait for it to * be closed without potentially deadlocking. */ return (EBADF); } KASSERT((ff->ff_refcnt & FR_CLOSING) == 0); /* * There may be multiple users of this file within the process. * Notify existing and new users that the file is closing. This * will prevent them from adding additional uses to this file * while we are closing it. */ atomic_store_relaxed(&ff->ff_file, NULL); ff->ff_exclose = false; /* * We expect the caller to hold a descriptor reference - drop it. * The reference count may increase beyond zero at this point due * to an erroneous descriptor reference by an application, but * fd_getfile() will notice that the file is being closed and drop * the reference again. */ if (fdp->fd_refcnt == 1) { /* Single threaded. */ refcnt = --(ff->ff_refcnt); } else { /* Multi threaded. */ membar_release(); refcnt = atomic_dec_uint_nv(&ff->ff_refcnt); membar_acquire(); } if (__predict_false(refcnt != 0)) { /* * Wait for other references to drain. This is typically * an application error - the descriptor is being closed * while still in use. * (Or just a threaded application trying to unblock its * thread that sleeps in (say) accept()). */ atomic_or_uint(&ff->ff_refcnt, FR_CLOSING); /* * Remove any knotes attached to the file. A knote * attached to the descriptor can hold references on it. */ mutex_exit(&fdp->fd_lock); if (!SLIST_EMPTY(&ff->ff_knlist)) { knote_fdclose(fd); } /* * Since the file system code doesn't know which fd * each request came from (think dup()), we have to * ask it to return ERESTART for any long-term blocks. * The re-entry through read/write/etc will detect the * closed fd and return EBAFD. * Blocked partial writes may return a short length. */ (*fp->f_ops->fo_restart)(fp); mutex_enter(&fdp->fd_lock); /* * We need to see the count drop to zero at least once, * in order to ensure that all pre-existing references * have been drained. New references past this point are * of no interest. * XXX (dsl) this may need to call fo_restart() after a * timeout to guarantee that all the system calls exit. */ while ((ff->ff_refcnt & FR_MASK) != 0) { cv_wait(&ff->ff_closing, &fdp->fd_lock); } atomic_and_uint(&ff->ff_refcnt, ~FR_CLOSING); } else { /* If no references, there must be no knotes. */ KASSERT(SLIST_EMPTY(&ff->ff_knlist)); } /* * POSIX record locking dictates that any close releases ALL * locks owned by this process. This is handled by setting * a flag in the unlock to free ONLY locks obeying POSIX * semantics, and not to free BSD-style file locks. * If the descriptor was in a message, POSIX-style locks * aren't passed with the descriptor. */ if (__predict_false((p->p_flag & PK_ADVLOCK) != 0) && fp->f_ops->fo_advlock != NULL) { lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; lf.l_type = F_UNLCK; mutex_exit(&fdp->fd_lock); (void)(*fp->f_ops->fo_advlock)(fp, p, F_UNLCK, &lf, F_POSIX); mutex_enter(&fdp->fd_lock); } /* Free descriptor slot. */ fd_unused(fdp, fd); mutex_exit(&fdp->fd_lock); /* Now drop reference to the file itself. */ return closef(fp); } /* * Duplicate a file descriptor. */ int fd_dup(file_t *fp, int minfd, int *newp, bool exclose) { proc_t *p = curproc; int error; while ((error = fd_alloc(p, minfd, newp)) != 0) { if (error != ENOSPC) { return error; } fd_tryexpand(p); } fd_set_exclose(curlwp, *newp, exclose); fd_affix(p, fp, *newp); return 0; } /* * dup2 operation. */ int fd_dup2(file_t *fp, unsigned newfd, int flags) { filedesc_t *fdp = curlwp->l_fd; fdfile_t *ff; fdtab_t *dt; if (flags & ~(O_CLOEXEC|O_NONBLOCK|O_NOSIGPIPE)) return EINVAL; /* * Ensure there are enough slots in the descriptor table, * and allocate an fdfile_t up front in case we need it. */ while (newfd >= atomic_load_consume(&fdp->fd_dt)->dt_nfiles) { fd_tryexpand(curproc); } ff = kmem_alloc(sizeof(*ff), KM_SLEEP); fdfile_ctor(ff); /* * If there is already a file open, close it. If the file is * half open, wait for it to be constructed before closing it. * XXX Potential for deadlock here? */ mutex_enter(&fdp->fd_lock); while (fd_isused(fdp, newfd)) { mutex_exit(&fdp->fd_lock); if (fd_getfile(newfd) != NULL) { (void)fd_close(newfd); } else { /* * Crummy, but unlikely to happen. * Can occur if we interrupt another * thread while it is opening a file. */ kpause("dup2", false, 1, NULL); } mutex_enter(&fdp->fd_lock); } dt = fdp->fd_dt; if (dt->dt_ff[newfd] == NULL) { KASSERT(newfd >= NDFDFILE); dt->dt_ff[newfd] = ff; ff = NULL; } fd_used(fdp, newfd); mutex_exit(&fdp->fd_lock); fd_set_exclose(curlwp, newfd, (flags & O_CLOEXEC) != 0); fp->f_flag |= flags & (FNONBLOCK|FNOSIGPIPE); /* Slot is now allocated. Insert copy of the file. */ fd_affix(curproc, fp, newfd); if (ff != NULL) { cv_destroy(&ff->ff_closing); kmem_free(ff, sizeof(*ff)); } return 0; } /* * Drop reference to a file structure. */ int closef(file_t *fp) { struct flock lf; int error; /* * Drop reference. If referenced elsewhere it's still open * and we have nothing more to do. */ mutex_enter(&fp->f_lock); KASSERT(fp->f_count > 0); if (--fp->f_count > 0) { mutex_exit(&fp->f_lock); return 0; } KASSERT(fp->f_count == 0); mutex_exit(&fp->f_lock); /* We held the last reference - release locks, close and free. */ if (fp->f_ops->fo_advlock == NULL) { KASSERT((fp->f_flag & FHASLOCK) == 0); } else if (fp->f_flag & FHASLOCK) { lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; lf.l_type = F_UNLCK; (void)(*fp->f_ops->fo_advlock)(fp, fp, F_UNLCK, &lf, F_FLOCK); } if (fp->f_ops != NULL) { error = (*fp->f_ops->fo_close)(fp); /* * .fo_close is final, so real errors are frowned on * (but allowed and passed on to close(2)), and * ERESTART is absolutely forbidden because the file * descriptor is gone and there is no chance to retry. */ KASSERTMSG(error != ERESTART, "file %p f_ops %p fo_close %p returned ERESTART", fp, fp->f_ops, fp->f_ops->fo_close); } else { error = 0; } KASSERT(fp->f_count == 0); KASSERT(fp->f_cred != NULL); pool_cache_put(file_cache, fp); return error; } /* * Allocate a file descriptor for the process. * * Future idea for experimentation: replace all of this with radixtree. */ int fd_alloc(proc_t *p, int want, int *result) { filedesc_t *fdp = p->p_fd; int i, lim, last, error, hi; u_int off; fdtab_t *dt; KASSERT(p == curproc || p == &proc0); /* * Search for a free descriptor starting at the higher * of want or fd_freefile. */ mutex_enter(&fdp->fd_lock); fd_checkmaps(fdp); dt = fdp->fd_dt; KASSERT(dt->dt_ff[0] == (fdfile_t *)fdp->fd_dfdfile[0]); lim = uimin((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfiles); last = uimin(dt->dt_nfiles, lim); for (;;) { if ((i = want) < fdp->fd_freefile) i = fdp->fd_freefile; off = i >> NDENTRYSHIFT; hi = fd_next_zero(fdp, fdp->fd_himap, off, (last + NDENTRIES - 1) >> NDENTRYSHIFT); if (hi == -1) break; i = fd_next_zero(fdp, &fdp->fd_lomap[hi], hi > off ? 0 : i & NDENTRYMASK, NDENTRIES); if (i == -1) { /* * Free file descriptor in this block was * below want, try again with higher want. */ want = (hi + 1) << NDENTRYSHIFT; continue; } i += (hi << NDENTRYSHIFT); if (i >= last) { break; } if (dt->dt_ff[i] == NULL) { KASSERT(i >= NDFDFILE); dt->dt_ff[i] = kmem_alloc(sizeof(fdfile_t), KM_SLEEP); fdfile_ctor(dt->dt_ff[i]); } KASSERT(dt->dt_ff[i]->ff_file == NULL); fd_used(fdp, i); if (want <= fdp->fd_freefile) { fdp->fd_freefile = i; } *result = i; KASSERT(i >= NDFDFILE || dt->dt_ff[i] == (fdfile_t *)fdp->fd_dfdfile[i]); fd_checkmaps(fdp); mutex_exit(&fdp->fd_lock); return 0; } /* No space in current array. Let the caller expand and retry. */ error = (dt->dt_nfiles >= lim) ? EMFILE : ENOSPC; mutex_exit(&fdp->fd_lock); return error; } /* * Allocate memory for a descriptor table. */ static fdtab_t * fd_dtab_alloc(int n) { fdtab_t *dt; size_t sz; KASSERT(n > NDFILE); sz = sizeof(*dt) + (n - NDFILE) * sizeof(dt->dt_ff[0]); dt = kmem_alloc(sz, KM_SLEEP); #ifdef DIAGNOSTIC memset(dt, 0xff, sz); #endif dt->dt_nfiles = n; dt->dt_link = NULL; return dt; } /* * Free a descriptor table, and all tables linked for deferred free. */ static void fd_dtab_free(fdtab_t *dt) { fdtab_t *next; size_t sz; do { next = dt->dt_link; KASSERT(dt->dt_nfiles > NDFILE); sz = sizeof(*dt) + (dt->dt_nfiles - NDFILE) * sizeof(dt->dt_ff[0]); #ifdef DIAGNOSTIC memset(dt, 0xff, sz); #endif kmem_free(dt, sz); dt = next; } while (dt != NULL); } /* * Allocate descriptor bitmap. */ static void fd_map_alloc(int n, uint32_t **lo, uint32_t **hi) { uint8_t *ptr; size_t szlo, szhi; KASSERT(n > NDENTRIES); szlo = NDLOSLOTS(n) * sizeof(uint32_t); szhi = NDHISLOTS(n) * sizeof(uint32_t); ptr = kmem_alloc(szlo + szhi, KM_SLEEP); *lo = (uint32_t *)ptr; *hi = (uint32_t *)(ptr + szlo); } /* * Free descriptor bitmap. */ static void fd_map_free(int n, uint32_t *lo, uint32_t *hi) { size_t szlo, szhi; KASSERT(n > NDENTRIES); szlo = NDLOSLOTS(n) * sizeof(uint32_t); szhi = NDHISLOTS(n) * sizeof(uint32_t); KASSERT(hi == (uint32_t *)((uint8_t *)lo + szlo)); kmem_free(lo, szlo + szhi); } /* * Expand a process' descriptor table. */ void fd_tryexpand(proc_t *p) { filedesc_t *fdp; int i, numfiles, oldnfiles; fdtab_t *newdt, *dt; uint32_t *newhimap, *newlomap; KASSERT(p == curproc || p == &proc0); fdp = p->p_fd; newhimap = NULL; newlomap = NULL; oldnfiles = atomic_load_consume(&fdp->fd_dt)->dt_nfiles; if (oldnfiles < NDEXTENT) numfiles = NDEXTENT; else numfiles = 2 * oldnfiles; newdt = fd_dtab_alloc(numfiles); if (NDHISLOTS(numfiles) > NDHISLOTS(oldnfiles)) { fd_map_alloc(numfiles, &newlomap, &newhimap); } mutex_enter(&fdp->fd_lock); dt = fdp->fd_dt; KASSERT(dt->dt_ff[0] == (fdfile_t *)fdp->fd_dfdfile[0]); if (dt->dt_nfiles != oldnfiles) { /* fdp changed; caller must retry */ mutex_exit(&fdp->fd_lock); fd_dtab_free(newdt); if (NDHISLOTS(numfiles) > NDHISLOTS(oldnfiles)) { fd_map_free(numfiles, newlomap, newhimap); } return; } /* Copy the existing descriptor table and zero the new portion. */ i = sizeof(fdfile_t *) * oldnfiles; memcpy(newdt->dt_ff, dt->dt_ff, i); memset((uint8_t *)newdt->dt_ff + i, 0, numfiles * sizeof(fdfile_t *) - i); /* * Link old descriptor array into list to be discarded. We defer * freeing until the last reference to the descriptor table goes * away (usually process exit). This allows us to do lockless * lookups in fd_getfile(). */ if (oldnfiles > NDFILE) { if (fdp->fd_refcnt > 1) { newdt->dt_link = dt; } else { fd_dtab_free(dt); } } if (NDHISLOTS(numfiles) > NDHISLOTS(oldnfiles)) { i = NDHISLOTS(oldnfiles) * sizeof(uint32_t); memcpy(newhimap, fdp->fd_himap, i); memset((uint8_t *)newhimap + i, 0, NDHISLOTS(numfiles) * sizeof(uint32_t) - i); i = NDLOSLOTS(oldnfiles) * sizeof(uint32_t); memcpy(newlomap, fdp->fd_lomap, i); memset((uint8_t *)newlomap + i, 0, NDLOSLOTS(numfiles) * sizeof(uint32_t) - i); if (NDHISLOTS(oldnfiles) > NDHISLOTS(NDFILE)) { fd_map_free(oldnfiles, fdp->fd_lomap, fdp->fd_himap); } fdp->fd_himap = newhimap; fdp->fd_lomap = newlomap; } /* * All other modifications must become globally visible before * the change to fd_dt. See fd_getfile(). */ atomic_store_release(&fdp->fd_dt, newdt); KASSERT(newdt->dt_ff[0] == (fdfile_t *)fdp->fd_dfdfile[0]); fd_checkmaps(fdp); mutex_exit(&fdp->fd_lock); } /* * Create a new open file structure and allocate a file descriptor * for the current process. */ int fd_allocfile(file_t **resultfp, int *resultfd) { proc_t *p = curproc; kauth_cred_t cred; file_t *fp; int error; while ((error = fd_alloc(p, 0, resultfd)) != 0) { if (error != ENOSPC) { return error; } fd_tryexpand(p); } fp = pool_cache_get(file_cache, PR_WAITOK); if (fp == NULL) { fd_abort(p, NULL, *resultfd); return ENFILE; } KASSERT(fp->f_count == 0); KASSERT(fp->f_msgcount == 0); KASSERT(fp->f_unpcount == 0); /* Replace cached credentials if not what we need. */ cred = curlwp->l_cred; if (__predict_false(cred != fp->f_cred)) { kauth_cred_free(fp->f_cred); fp->f_cred = kauth_cred_hold(cred); } /* * Don't allow recycled files to be scanned. * See uipc_usrreq.c. */ if (__predict_false((fp->f_flag & FSCAN) != 0)) { mutex_enter(&fp->f_lock); atomic_and_uint(&fp->f_flag, ~FSCAN); mutex_exit(&fp->f_lock); } fp->f_advice = 0; fp->f_offset = 0; *resultfp = fp; return 0; } /* * Successful creation of a new descriptor: make visible to the process. */ void fd_affix(proc_t *p, file_t *fp, unsigned fd) { fdfile_t *ff; filedesc_t *fdp; fdtab_t *dt; KASSERT(p == curproc || p == &proc0); /* Add a reference to the file structure. */ mutex_enter(&fp->f_lock); fp->f_count++; mutex_exit(&fp->f_lock); /* * Insert the new file into the descriptor slot. */ fdp = p->p_fd; dt = atomic_load_consume(&fdp->fd_dt); ff = dt->dt_ff[fd]; KASSERT(ff != NULL); KASSERT(ff->ff_file == NULL); KASSERT(ff->ff_allocated); KASSERT(fd_isused(fdp, fd)); KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); /* No need to lock in order to make file initially visible. */ atomic_store_release(&ff->ff_file, fp); } /* * Abort creation of a new descriptor: free descriptor slot and file. */ void fd_abort(proc_t *p, file_t *fp, unsigned fd) { filedesc_t *fdp; fdfile_t *ff; KASSERT(p == curproc || p == &proc0); fdp = p->p_fd; ff = atomic_load_consume(&fdp->fd_dt)->dt_ff[fd]; ff->ff_exclose = false; KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); mutex_enter(&fdp->fd_lock); KASSERT(fd_isused(fdp, fd)); fd_unused(fdp, fd); mutex_exit(&fdp->fd_lock); if (fp != NULL) { KASSERT(fp->f_count == 0); KASSERT(fp->f_cred != NULL); pool_cache_put(file_cache, fp); } } static int file_ctor(void *arg, void *obj, int flags) { /* * It's easy to exhaust the open file limit on a system with many * CPUs due to caching. Allow a bit of leeway to reduce the element * of surprise. */ u_int slop = PCG_NOBJECTS_NORMAL * (ncpu - 1); file_t *fp = obj; memset(fp, 0, sizeof(*fp)); mutex_enter(&filelist_lock); if (__predict_false(nfiles >= slop + maxfiles)) { mutex_exit(&filelist_lock); tablefull("file", "increase kern.maxfiles or MAXFILES"); return ENFILE; } nfiles++; LIST_INSERT_HEAD(&filehead, fp, f_list); mutex_init(&fp->f_lock, MUTEX_DEFAULT, IPL_NONE); fp->f_cred = kauth_cred_hold(curlwp->l_cred); mutex_exit(&filelist_lock); return 0; } static void file_dtor(void *arg, void *obj) { file_t *fp = obj; mutex_enter(&filelist_lock); nfiles--; LIST_REMOVE(fp, f_list); mutex_exit(&filelist_lock); KASSERT(fp->f_count == 0); kauth_cred_free(fp->f_cred); mutex_destroy(&fp->f_lock); } static void fdfile_ctor(fdfile_t *ff) { memset(ff, 0, sizeof(*ff)); cv_init(&ff->ff_closing, "fdclose"); } static void fdfile_dtor(fdfile_t *ff) { cv_destroy(&ff->ff_closing); } file_t * fgetdummy(void) { file_t *fp; fp = kmem_zalloc(sizeof(*fp), KM_SLEEP); mutex_init(&fp->f_lock, MUTEX_DEFAULT, IPL_NONE); return fp; } void fputdummy(file_t *fp) { mutex_destroy(&fp->f_lock); kmem_free(fp, sizeof(*fp)); } /* * Create an initial filedesc structure. */ filedesc_t * fd_init(filedesc_t *fdp) { #ifdef DIAGNOSTIC unsigned fd; #endif if (__predict_true(fdp == NULL)) { fdp = pool_cache_get(filedesc_cache, PR_WAITOK); } else { KASSERT(fdp == &filedesc0); filedesc_ctor(NULL, fdp, PR_WAITOK); } #ifdef DIAGNOSTIC KASSERT(fdp->fd_lastfile == -1); KASSERT(fdp->fd_lastkqfile == -1); KASSERT(fdp->fd_knhash == NULL); KASSERT(fdp->fd_freefile == 0); KASSERT(fdp->fd_exclose == false); KASSERT(fdp->fd_dt == &fdp->fd_dtbuiltin); KASSERT(fdp->fd_dtbuiltin.dt_nfiles == NDFILE); for (fd = 0; fd < NDFDFILE; fd++) { KASSERT(fdp->fd_dtbuiltin.dt_ff[fd] == (fdfile_t *)fdp->fd_dfdfile[fd]); } for (fd = NDFDFILE; fd < NDFILE; fd++) { KASSERT(fdp->fd_dtbuiltin.dt_ff[fd] == NULL); } KASSERT(fdp->fd_himap == fdp->fd_dhimap); KASSERT(fdp->fd_lomap == fdp->fd_dlomap); #endif /* DIAGNOSTIC */ fdp->fd_refcnt = 1; fd_checkmaps(fdp); return fdp; } /* * Initialize a file descriptor table. */ static int filedesc_ctor(void *arg, void *obj, int flag) { filedesc_t *fdp = obj; fdfile_t **ffp; int i; memset(fdp, 0, sizeof(*fdp)); mutex_init(&fdp->fd_lock, MUTEX_DEFAULT, IPL_NONE); fdp->fd_lastfile = -1; fdp->fd_lastkqfile = -1; fdp->fd_dt = &fdp->fd_dtbuiltin; fdp->fd_dtbuiltin.dt_nfiles = NDFILE; fdp->fd_himap = fdp->fd_dhimap; fdp->fd_lomap = fdp->fd_dlomap; CTASSERT(sizeof(fdp->fd_dfdfile[0]) >= sizeof(fdfile_t)); for (i = 0, ffp = fdp->fd_dt->dt_ff; i < NDFDFILE; i++, ffp++) { fdfile_ctor(*ffp = (fdfile_t *)fdp->fd_dfdfile[i]); } return 0; } static void filedesc_dtor(void *arg, void *obj) { filedesc_t *fdp = obj; int i; for (i = 0; i < NDFDFILE; i++) { fdfile_dtor((fdfile_t *)fdp->fd_dfdfile[i]); } mutex_destroy(&fdp->fd_lock); } /* * Make p share curproc's filedesc structure. */ void fd_share(struct proc *p) { filedesc_t *fdp; fdp = curlwp->l_fd; p->p_fd = fdp; atomic_inc_uint(&fdp->fd_refcnt); } /* * Acquire a hold on a filedesc structure. */ void fd_hold(lwp_t *l) { filedesc_t *fdp = l->l_fd; atomic_inc_uint(&fdp->fd_refcnt); } /* * Copy a filedesc structure. */ filedesc_t * fd_copy(void) { filedesc_t *newfdp, *fdp; fdfile_t *ff, **ffp, **nffp, *ff2; int i, j, numfiles, lastfile, newlast; file_t *fp; fdtab_t *newdt; fdp = curproc->p_fd; newfdp = pool_cache_get(filedesc_cache, PR_WAITOK); newfdp->fd_refcnt = 1; #ifdef DIAGNOSTIC KASSERT(newfdp->fd_lastfile == -1); KASSERT(newfdp->fd_lastkqfile == -1); KASSERT(newfdp->fd_knhash == NULL); KASSERT(newfdp->fd_freefile == 0); KASSERT(newfdp->fd_exclose == false); KASSERT(newfdp->fd_dt == &newfdp->fd_dtbuiltin); KASSERT(newfdp->fd_dtbuiltin.dt_nfiles == NDFILE); for (i = 0; i < NDFDFILE; i++) { KASSERT(newfdp->fd_dtbuiltin.dt_ff[i] == (fdfile_t *)&newfdp->fd_dfdfile[i]); } for (i = NDFDFILE; i < NDFILE; i++) { KASSERT(newfdp->fd_dtbuiltin.dt_ff[i] == NULL); } #endif /* DIAGNOSTIC */ mutex_enter(&fdp->fd_lock); fd_checkmaps(fdp); numfiles = fdp->fd_dt->dt_nfiles; lastfile = fdp->fd_lastfile; /* * If the number of open files fits in the internal arrays * of the open file structure, use them, otherwise allocate * additional memory for the number of descriptors currently * in use. */ if (lastfile < NDFILE) { i = NDFILE; newdt = newfdp->fd_dt; KASSERT(newfdp->fd_dt == &newfdp->fd_dtbuiltin); } else { /* * Compute the smallest multiple of NDEXTENT needed * for the file descriptors currently in use, * allowing the table to shrink. */ i = numfiles; while (i >= 2 * NDEXTENT && i > lastfile * 2) { i /= 2; } KASSERT(i > NDFILE); newdt = fd_dtab_alloc(i); newfdp->fd_dt = newdt; memcpy(newdt->dt_ff, newfdp->fd_dtbuiltin.dt_ff, NDFDFILE * sizeof(fdfile_t **)); memset(newdt->dt_ff + NDFDFILE, 0, (i - NDFDFILE) * sizeof(fdfile_t **)); } if (NDHISLOTS(i) <= NDHISLOTS(NDFILE)) { newfdp->fd_himap = newfdp->fd_dhimap; newfdp->fd_lomap = newfdp->fd_dlomap; } else { fd_map_alloc(i, &newfdp->fd_lomap, &newfdp->fd_himap); KASSERT(i >= NDENTRIES * NDENTRIES); memset(newfdp->fd_himap, 0, NDHISLOTS(i)*sizeof(uint32_t)); memset(newfdp->fd_lomap, 0, NDLOSLOTS(i)*sizeof(uint32_t)); } newfdp->fd_freefile = fdp->fd_freefile; newfdp->fd_exclose = fdp->fd_exclose; ffp = fdp->fd_dt->dt_ff; nffp = newdt->dt_ff; newlast = -1; for (i = 0; i <= lastfile; i++, ffp++, nffp++) { KASSERT(i >= NDFDFILE || *nffp == (fdfile_t *)newfdp->fd_dfdfile[i]); ff = *ffp; if (ff == NULL || (fp = atomic_load_consume(&ff->ff_file)) == NULL) { /* Descriptor unused, or descriptor half open. */ KASSERT(!fd_isused(newfdp, i)); continue; } if (__predict_false(fp->f_type == DTYPE_KQUEUE)) { /* kqueue descriptors cannot be copied. */ if (i < newfdp->fd_freefile) { newfdp->fd_freefile = i; } continue; } /* It's active: add a reference to the file. */ mutex_enter(&fp->f_lock); fp->f_count++; mutex_exit(&fp->f_lock); /* Allocate an fdfile_t to represent it. */ if (i >= NDFDFILE) { ff2 = kmem_alloc(sizeof(*ff2), KM_SLEEP); fdfile_ctor(ff2); *nffp = ff2; } else { ff2 = newdt->dt_ff[i]; } ff2->ff_file = fp; ff2->ff_exclose = ff->ff_exclose; ff2->ff_allocated = true; /* Fix up bitmaps. */ j = i >> NDENTRYSHIFT; KASSERT((newfdp->fd_lomap[j] & (1U << (i & NDENTRYMASK))) == 0); newfdp->fd_lomap[j] |= 1U << (i & NDENTRYMASK); if (__predict_false(newfdp->fd_lomap[j] == ~0)) { KASSERT((newfdp->fd_himap[j >> NDENTRYSHIFT] & (1U << (j & NDENTRYMASK))) == 0); newfdp->fd_himap[j >> NDENTRYSHIFT] |= 1U << (j & NDENTRYMASK); } newlast = i; } KASSERT(newdt->dt_ff[0] == (fdfile_t *)newfdp->fd_dfdfile[0]); newfdp->fd_lastfile = newlast; fd_checkmaps(newfdp); mutex_exit(&fdp->fd_lock); return newfdp; } /* * Release a filedesc structure. */ void fd_free(void) { fdfile_t *ff; file_t *fp; int fd, nf; fdtab_t *dt; lwp_t * const l = curlwp; filedesc_t * const fdp = l->l_fd; const bool noadvlock = (l->l_proc->p_flag & PK_ADVLOCK) == 0; KASSERT(atomic_load_consume(&fdp->fd_dt)->dt_ff[0] == (fdfile_t *)fdp->fd_dfdfile[0]); KASSERT(fdp->fd_dtbuiltin.dt_nfiles == NDFILE); KASSERT(fdp->fd_dtbuiltin.dt_link == NULL); membar_release(); if (atomic_dec_uint_nv(&fdp->fd_refcnt) > 0) return; membar_acquire(); /* * Close any files that the process holds open. */ dt = fdp->fd_dt; fd_checkmaps(fdp); #ifdef DEBUG fdp->fd_refcnt = -1; /* see fd_checkmaps */ #endif for (fd = 0, nf = dt->dt_nfiles; fd < nf; fd++) { ff = dt->dt_ff[fd]; KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); if (ff == NULL) continue; if ((fp = atomic_load_consume(&ff->ff_file)) != NULL) { /* * Must use fd_close() here if there is * a reference from kqueue or we might have posix * advisory locks. */ if (__predict_true(ff->ff_refcnt == 0) && (noadvlock || fp->f_type != DTYPE_VNODE)) { ff->ff_file = NULL; ff->ff_exclose = false; ff->ff_allocated = false; closef(fp); } else { ff->ff_refcnt++; fd_close(fd); } } KASSERT(ff->ff_refcnt == 0); KASSERT(ff->ff_file == NULL); KASSERT(!ff->ff_exclose); KASSERT(!ff->ff_allocated); if (fd >= NDFDFILE) { cv_destroy(&ff->ff_closing); kmem_free(ff, sizeof(*ff)); dt->dt_ff[fd] = NULL; } } /* * Clean out the descriptor table for the next user and return * to the cache. */ if (__predict_false(dt != &fdp->fd_dtbuiltin)) { fd_dtab_free(fdp->fd_dt); /* Otherwise, done above. */ memset(&fdp->fd_dtbuiltin.dt_ff[NDFDFILE], 0, (NDFILE - NDFDFILE) * sizeof(fdp->fd_dtbuiltin.dt_ff[0])); fdp->fd_dt = &fdp->fd_dtbuiltin; } if (__predict_false(NDHISLOTS(nf) > NDHISLOTS(NDFILE))) { KASSERT(fdp->fd_himap != fdp->fd_dhimap); KASSERT(fdp->fd_lomap != fdp->fd_dlomap); fd_map_free(nf, fdp->fd_lomap, fdp->fd_himap); } if (__predict_false(fdp->fd_knhash != NULL)) { hashdone(fdp->fd_knhash, HASH_LIST, fdp->fd_knhashmask); fdp->fd_knhash = NULL; fdp->fd_knhashmask = 0; } else { KASSERT(fdp->fd_knhashmask == 0); } fdp->fd_dt = &fdp->fd_dtbuiltin; fdp->fd_lastkqfile = -1; fdp->fd_lastfile = -1; fdp->fd_freefile = 0; fdp->fd_exclose = false; memset(&fdp->fd_startzero, 0, sizeof(*fdp) - offsetof(filedesc_t, fd_startzero)); fdp->fd_himap = fdp->fd_dhimap; fdp->fd_lomap = fdp->fd_dlomap; KASSERT(fdp->fd_dtbuiltin.dt_nfiles == NDFILE); KASSERT(fdp->fd_dtbuiltin.dt_link == NULL); KASSERT(fdp->fd_dt == &fdp->fd_dtbuiltin); #ifdef DEBUG fdp->fd_refcnt = 0; /* see fd_checkmaps */ #endif fd_checkmaps(fdp); pool_cache_put(filedesc_cache, fdp); } /* * File Descriptor pseudo-device driver (/dev/fd/). * * Opening minor device N dup()s the file (if any) connected to file * descriptor N belonging to the calling process. Note that this driver * consists of only the ``open()'' routine, because all subsequent * references to this file will be direct to the other driver. */ static int filedescopen(dev_t dev, int mode, int type, lwp_t *l) { /* * XXX Kludge: set dupfd to contain the value of the * the file descriptor being sought for duplication. The error * return ensures that the vnode for this device will be released * by vn_open. Open will detect this special error and take the * actions in fd_dupopen below. Other callers of vn_open or VOP_OPEN * will simply report the error. */ l->l_dupfd = minor(dev); /* XXX */ return EDUPFD; } /* * Duplicate the specified descriptor to a free descriptor. * * old is the original fd. * moveit is true if we should move rather than duplicate. * flags are the open flags (converted from O_* to F*). * newp returns the new fd on success. * * These two cases are produced by the EDUPFD and EMOVEFD magic * errnos, but in the interest of removing that regrettable interface, * vn_open has been changed to intercept them. Now vn_open returns * either a vnode or a filehandle, and the filehandle is accompanied * by a boolean that says whether we should dup (moveit == false) or * move (moveit == true) the fd. * * The dup case is used by /dev/stderr, /proc/self/fd, and such. The * move case is used by cloner devices that allocate a fd of their * own (a layering violation that should go away eventually) that * then needs to be put in the place open() expects it. */ int fd_dupopen(int old, bool moveit, int flags, int *newp) { filedesc_t *fdp; fdfile_t *ff; file_t *fp; fdtab_t *dt; int error; if ((fp = fd_getfile(old)) == NULL) { return EBADF; } fdp = curlwp->l_fd; dt = atomic_load_consume(&fdp->fd_dt); ff = dt->dt_ff[old]; /* * There are two cases of interest here. * * 1. moveit == false (used to be the EDUPFD magic errno): * simply dup (old) to file descriptor (new) and return. * * 2. moveit == true (used to be the EMOVEFD magic errno): * steal away the file structure from (old) and store it in * (new). (old) is effectively closed by this operation. */ if (moveit == false) { /* * Check that the mode the file is being opened for is a * subset of the mode of the existing descriptor. */ if (((flags & (FREAD|FWRITE)) | fp->f_flag) != fp->f_flag) { error = EACCES; goto out; } /* Copy it. */ error = fd_dup(fp, 0, newp, ff->ff_exclose); } else { /* Copy it. */ error = fd_dup(fp, 0, newp, ff->ff_exclose); if (error != 0) { goto out; } /* Steal away the file pointer from 'old'. */ (void)fd_close(old); return 0; } out: fd_putfile(old); return error; } /* * Close open files on exec. */ void fd_closeexec(void) { proc_t *p; filedesc_t *fdp; fdfile_t *ff; lwp_t *l; fdtab_t *dt; int fd; l = curlwp; p = l->l_proc; fdp = p->p_fd; if (fdp->fd_refcnt > 1) { fdp = fd_copy(); fd_free(); p->p_fd = fdp; l->l_fd = fdp; } if (!fdp->fd_exclose) { return; } fdp->fd_exclose = false; dt = atomic_load_consume(&fdp->fd_dt); for (fd = 0; fd <= fdp->fd_lastfile; fd++) { if ((ff = dt->dt_ff[fd]) == NULL) { KASSERT(fd >= NDFDFILE); continue; } KASSERT(fd >= NDFDFILE || ff == (fdfile_t *)fdp->fd_dfdfile[fd]); if (ff->ff_file == NULL) continue; if (ff->ff_exclose) { /* * We need a reference to close the file. * No other threads can see the fdfile_t at * this point, so don't bother locking. */ KASSERT((ff->ff_refcnt & FR_CLOSING) == 0); ff->ff_refcnt++; fd_close(fd); } } } /* * Sets descriptor owner. If the owner is a process, 'pgid' * is set to positive value, process ID. If the owner is process group, * 'pgid' is set to -pg_id. */ int fsetown(pid_t *pgid, u_long cmd, const void *data) { pid_t id = *(const pid_t *)data; int error; if (id <= INT_MIN) return EINVAL; switch (cmd) { case TIOCSPGRP: if (id < 0) return EINVAL; id = -id; break; default: break; } if (id > 0) { mutex_enter(&proc_lock); error = proc_find(id) ? 0 : ESRCH; mutex_exit(&proc_lock); } else if (id < 0) { error = pgid_in_session(curproc, -id); } else { error = 0; } if (!error) { *pgid = id; } return error; } void fd_set_exclose(struct lwp *l, int fd, bool exclose) { filedesc_t *fdp = l->l_fd; fdfile_t *ff = atomic_load_consume(&fdp->fd_dt)->dt_ff[fd]; ff->ff_exclose = exclose; if (exclose) fdp->fd_exclose = true; } /* * Return descriptor owner information. If the value is positive, * it's process ID. If it's negative, it's process group ID and * needs the sign removed before use. */ int fgetown(pid_t pgid, u_long cmd, void *data) { switch (cmd) { case TIOCGPGRP: KASSERT(pgid > INT_MIN); *(int *)data = -pgid; break; default: *(int *)data = pgid; break; } return 0; } /* * Send signal to descriptor owner, either process or process group. */ void fownsignal(pid_t pgid, int signo, int code, int band, void *fdescdata) { ksiginfo_t ksi; KASSERT(!cpu_intr_p()); if (pgid == 0) { return; } KSI_INIT(&ksi); ksi.ksi_signo = signo; ksi.ksi_code = code; ksi.ksi_band = band; mutex_enter(&proc_lock); if (pgid > 0) { struct proc *p1; p1 = proc_find(pgid); if (p1 != NULL) { kpsignal(p1, &ksi, fdescdata); } } else { struct pgrp *pgrp; KASSERT(pgid < 0 && pgid > INT_MIN); pgrp = pgrp_find(-pgid); if (pgrp != NULL) { kpgsignal(pgrp, &ksi, fdescdata, 0); } } mutex_exit(&proc_lock); } int fd_clone(file_t *fp, unsigned fd, int flag, const struct fileops *fops, void *data) { fp->f_flag = flag & FMASK; fd_set_exclose(curlwp, fd, (flag & O_CLOEXEC) != 0); fp->f_type = DTYPE_MISC; fp->f_ops = fops; fp->f_data = data; curlwp->l_dupfd = fd; fd_affix(curproc, fp, fd); return EMOVEFD; } int fnullop_fcntl(file_t *fp, u_int cmd, void *data) { if (cmd == F_SETFL) return 0; return EOPNOTSUPP; } int fnullop_poll(file_t *fp, int which) { return 0; } int fnullop_kqfilter(file_t *fp, struct knote *kn) { return EOPNOTSUPP; } void fnullop_restart(file_t *fp) { } int fbadop_read(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred, int flags) { return EOPNOTSUPP; } int fbadop_write(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred, int flags) { return EOPNOTSUPP; } int fbadop_ioctl(file_t *fp, u_long com, void *data) { return EOPNOTSUPP; } int fbadop_stat(file_t *fp, struct stat *sb) { return EOPNOTSUPP; } int fbadop_close(file_t *fp) { return EOPNOTSUPP; } /* * sysctl routines pertaining to file descriptors */ /* Initialized in sysctl_init() for now... */ extern kmutex_t sysctl_file_marker_lock; static u_int sysctl_file_marker = 1; /* * Expects to be called with proc_lock and sysctl_file_marker_lock locked. */ static void sysctl_file_marker_reset(void) { struct proc *p; PROCLIST_FOREACH(p, &allproc) { struct filedesc *fd = p->p_fd; fdtab_t *dt; u_int i; mutex_enter(&fd->fd_lock); dt = fd->fd_dt; for (i = 0; i < dt->dt_nfiles; i++) { struct file *fp; fdfile_t *ff; if ((ff = dt->dt_ff[i]) == NULL) { continue; } if ((fp = atomic_load_consume(&ff->ff_file)) == NULL) { continue; } fp->f_marker = 0; } mutex_exit(&fd->fd_lock); } } /* * sysctl helper routine for kern.file pseudo-subtree. */ static int sysctl_kern_file(SYSCTLFN_ARGS) { const bool allowaddr = get_expose_address(curproc); struct filelist flist; int error; size_t buflen; struct file *fp, fbuf; char *start, *where; struct proc *p; start = where = oldp; buflen = *oldlenp; if (where == NULL) { /* * overestimate by 10 files */ *oldlenp = sizeof(filehead) + (nfiles + 10) * sizeof(struct file); return 0; } /* * first sysctl_copyout filehead */ if (buflen < sizeof(filehead)) { *oldlenp = 0; return 0; } sysctl_unlock(); if (allowaddr) { memcpy(&flist, &filehead, sizeof(flist)); } else { memset(&flist, 0, sizeof(flist)); } error = sysctl_copyout(l, &flist, where, sizeof(flist)); if (error) { sysctl_relock(); return error; } buflen -= sizeof(flist); where += sizeof(flist); /* * followed by an array of file structures */ mutex_enter(&sysctl_file_marker_lock); mutex_enter(&proc_lock); PROCLIST_FOREACH(p, &allproc) { struct filedesc *fd; fdtab_t *dt; u_int i; if (p->p_stat == SIDL) { /* skip embryonic processes */ continue; } mutex_enter(p->p_lock); error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE, p, KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_OPENFILES), NULL, NULL); mutex_exit(p->p_lock); if (error != 0) { /* * Don't leak kauth retval if we're silently * skipping this entry. */ error = 0; continue; } /* * Grab a hold on the process. */ if (!rw_tryenter(&p->p_reflock, RW_READER)) { continue; } mutex_exit(&proc_lock); fd = p->p_fd; mutex_enter(&fd->fd_lock); dt = fd->fd_dt; for (i = 0; i < dt->dt_nfiles; i++) { fdfile_t *ff; if ((ff = dt->dt_ff[i]) == NULL) { continue; } if ((fp = atomic_load_consume(&ff->ff_file)) == NULL) { continue; } mutex_enter(&fp->f_lock); if ((fp->f_count == 0) || (fp->f_marker == sysctl_file_marker)) { mutex_exit(&fp->f_lock); continue; } /* Check that we have enough space. */ if (buflen < sizeof(struct file)) { *oldlenp = where - start; mutex_exit(&fp->f_lock); error = ENOMEM; break; } fill_file(&fbuf, fp); mutex_exit(&fp->f_lock); error = sysctl_copyout(l, &fbuf, where, sizeof(fbuf)); if (error) { break; } buflen -= sizeof(struct file); where += sizeof(struct file); fp->f_marker = sysctl_file_marker; } mutex_exit(&fd->fd_lock); /* * Release reference to process. */ mutex_enter(&proc_lock); rw_exit(&p->p_reflock); if (error) break; } sysctl_file_marker++; /* Reset all markers if wrapped. */ if (sysctl_file_marker == 0) { sysctl_file_marker_reset(); sysctl_file_marker++; } mutex_exit(&proc_lock); mutex_exit(&sysctl_file_marker_lock); *oldlenp = where - start; sysctl_relock(); return error; } /* * sysctl helper function for kern.file2 */ static int sysctl_kern_file2(SYSCTLFN_ARGS) { struct proc *p; struct file *fp; struct filedesc *fd; struct kinfo_file kf; char *dp; u_int i, op; size_t len, needed, elem_size, out_size; int error, arg, elem_count; fdfile_t *ff; fdtab_t *dt; if (namelen == 1 && name[0] == CTL_QUERY) return sysctl_query(SYSCTLFN_CALL(rnode)); if (namelen != 4) return EINVAL; error = 0; dp = oldp; len = (oldp != NULL) ? *oldlenp : 0; op = name[0]; arg = name[1]; elem_size = name[2]; elem_count = name[3]; out_size = MIN(sizeof(kf), elem_size); needed = 0; if (elem_size < 1 || elem_count < 0) return EINVAL; switch (op) { case KERN_FILE_BYFILE: case KERN_FILE_BYPID: /* * We're traversing the process list in both cases; the BYFILE * case does additional work of keeping track of files already * looked at. */ /* doesn't use arg so it must be zero */ if ((op == KERN_FILE_BYFILE) && (arg != 0)) return EINVAL; if ((op == KERN_FILE_BYPID) && (arg < -1)) /* -1 means all processes */ return EINVAL; sysctl_unlock(); if (op == KERN_FILE_BYFILE) mutex_enter(&sysctl_file_marker_lock); mutex_enter(&proc_lock); PROCLIST_FOREACH(p, &allproc) { if (p->p_stat == SIDL) { /* skip embryonic processes */ continue; } if (arg > 0 && p->p_pid != arg) { /* pick only the one we want */ /* XXX want 0 to mean "kernel files" */ continue; } mutex_enter(p->p_lock); error = kauth_authorize_process(l->l_cred, KAUTH_PROCESS_CANSEE, p, KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_OPENFILES), NULL, NULL); mutex_exit(p->p_lock); if (error != 0) { /* * Don't leak kauth retval if we're silently * skipping this entry. */ error = 0; continue; } /* * Grab a hold on the process. */ if (!rw_tryenter(&p->p_reflock, RW_READER)) { continue; } mutex_exit(&proc_lock); fd = p->p_fd; mutex_enter(&fd->fd_lock); dt = fd->fd_dt; for (i = 0; i < dt->dt_nfiles; i++) { if ((ff = dt->dt_ff[i]) == NULL) { continue; } if ((fp = atomic_load_consume(&ff->ff_file)) == NULL) { continue; } if ((op == KERN_FILE_BYFILE) && (fp->f_marker == sysctl_file_marker)) { continue; } if (len >= elem_size && elem_count > 0) { mutex_enter(&fp->f_lock); fill_file2(&kf, fp, ff, i, p->p_pid); mutex_exit(&fp->f_lock); mutex_exit(&fd->fd_lock); error = sysctl_copyout(l, &kf, dp, out_size); mutex_enter(&fd->fd_lock); if (error) break; dp += elem_size; len -= elem_size; } if (op == KERN_FILE_BYFILE) fp->f_marker = sysctl_file_marker; needed += elem_size; if (elem_count > 0 && elem_count != INT_MAX) elem_count--; } mutex_exit(&fd->fd_lock); /* * Release reference to process. */ mutex_enter(&proc_lock); rw_exit(&p->p_reflock); } if (op == KERN_FILE_BYFILE) { sysctl_file_marker++; /* Reset all markers if wrapped. */ if (sysctl_file_marker == 0) { sysctl_file_marker_reset(); sysctl_file_marker++; } } mutex_exit(&proc_lock); if (op == KERN_FILE_BYFILE) mutex_exit(&sysctl_file_marker_lock); sysctl_relock(); break; default: return EINVAL; } if (oldp == NULL) needed += KERN_FILESLOP * elem_size; *oldlenp = needed; return error; } static void fill_file(struct file *fp, const struct file *fpsrc) { const bool allowaddr = get_expose_address(curproc); memset(fp, 0, sizeof(*fp)); fp->f_offset = fpsrc->f_offset; COND_SET_PTR(fp->f_cred, fpsrc->f_cred, allowaddr); COND_SET_CPTR(fp->f_ops, fpsrc->f_ops, allowaddr); COND_SET_STRUCT(fp->f_undata, fpsrc->f_undata, allowaddr); COND_SET_STRUCT(fp->f_list, fpsrc->f_list, allowaddr); fp->f_flag = fpsrc->f_flag; fp->f_marker = fpsrc->f_marker; fp->f_type = fpsrc->f_type; fp->f_advice = fpsrc->f_advice; fp->f_count = fpsrc->f_count; fp->f_msgcount = fpsrc->f_msgcount; fp->f_unpcount = fpsrc->f_unpcount; COND_SET_STRUCT(fp->f_unplist, fpsrc->f_unplist, allowaddr); } static void fill_file2(struct kinfo_file *kp, const file_t *fp, const fdfile_t *ff, int i, pid_t pid) { const bool allowaddr = get_expose_address(curproc); memset(kp, 0, sizeof(*kp)); COND_SET_VALUE(kp->ki_fileaddr, PTRTOUINT64(fp), allowaddr); kp->ki_flag = fp->f_flag; kp->ki_iflags = 0; kp->ki_ftype = fp->f_type; kp->ki_count = fp->f_count; kp->ki_msgcount = fp->f_msgcount; COND_SET_VALUE(kp->ki_fucred, PTRTOUINT64(fp->f_cred), allowaddr); kp->ki_fuid = kauth_cred_geteuid(fp->f_cred); kp->ki_fgid = kauth_cred_getegid(fp->f_cred); COND_SET_VALUE(kp->ki_fops, PTRTOUINT64(fp->f_ops), allowaddr); kp->ki_foffset = fp->f_offset; COND_SET_VALUE(kp->ki_fdata, PTRTOUINT64(fp->f_data), allowaddr); /* vnode information to glue this file to something */ if (fp->f_type == DTYPE_VNODE) { struct vnode *vp = fp->f_vnode; COND_SET_VALUE(kp->ki_vun, PTRTOUINT64(vp->v_un.vu_socket), allowaddr); kp->ki_vsize = vp->v_size; kp->ki_vtype = vp->v_type; kp->ki_vtag = vp->v_tag; COND_SET_VALUE(kp->ki_vdata, PTRTOUINT64(vp->v_data), allowaddr); } /* process information when retrieved via KERN_FILE_BYPID */ if (ff != NULL) { kp->ki_pid = pid; kp->ki_fd = i; kp->ki_ofileflags = ff->ff_exclose; kp->ki_usecount = ff->ff_refcnt; } }