/* * Copyright (c) 2005 The DragonFly Project. All rights reserved. * * This code is derived from software contributed to The DragonFly Project * by Jeffrey Hsu. * * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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 * COPYRIGHT HOLDERS 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_descrip.c 8.6 (Berkeley) 4/19/94 * $FreeBSD: src/sys/kern/kern_descrip.c,v 1.81.2.19 2004/02/28 00:43:31 tegge Exp $ * $DragonFly: src/sys/kern/kern_descrip.c,v 1.76 2006/12/23 00:35:03 swildner Exp $ */ #include "opt_compat.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd); static void fdreserve_locked (struct filedesc *fdp, int fd0, int incr); static struct file *funsetfd_locked (struct filedesc *fdp, int fd); static int checkfpclosed(struct filedesc *fdp, int fd, struct file *fp); static void ffree(struct file *fp); static MALLOC_DEFINE(M_FILEDESC, "file desc", "Open file descriptor table"); static MALLOC_DEFINE(M_FILEDESC_TO_LEADER, "file desc to leader", "file desc to leader structures"); MALLOC_DEFINE(M_FILE, "file", "Open file structure"); static MALLOC_DEFINE(M_SIGIO, "sigio", "sigio structures"); static d_open_t fdopen; #define NUMFDESC 64 #define CDEV_MAJOR 22 static struct dev_ops fildesc_ops = { { "FD", CDEV_MAJOR, 0 }, .d_open = fdopen, }; static int badfo_readwrite (struct file *fp, struct uio *uio, struct ucred *cred, int flags); static int badfo_ioctl (struct file *fp, u_long com, caddr_t data, struct ucred *cred); static int badfo_poll (struct file *fp, int events, struct ucred *cred); static int badfo_kqfilter (struct file *fp, struct knote *kn); static int badfo_stat (struct file *fp, struct stat *sb, struct ucred *cred); static int badfo_close (struct file *fp); static int badfo_shutdown (struct file *fp, int how); /* * Descriptor management. */ static struct filelist filehead = LIST_HEAD_INITIALIZER(&filehead); static struct spinlock filehead_spin = SPINLOCK_INITIALIZER(&filehead_spin); static int nfiles; /* actual number of open files */ extern int cmask; /* * Fixup fd_freefile and fd_lastfile after a descriptor has been cleared. * * MPSAFE - must be called with fdp->fd_spin exclusively held */ static __inline void fdfixup_locked(struct filedesc *fdp, int fd) { if (fd < fdp->fd_freefile) { fdp->fd_freefile = fd; } while (fdp->fd_lastfile >= 0 && fdp->fd_files[fdp->fd_lastfile].fp == NULL && fdp->fd_files[fdp->fd_lastfile].reserved == 0 ) { --fdp->fd_lastfile; } } /* * System calls on descriptors. * * MPSAFE */ int sys_getdtablesize(struct getdtablesize_args *uap) { struct proc *p = curproc; struct plimit *limit = p->p_limit; spin_lock_rd(&limit->p_spin); uap->sysmsg_result = min((int)limit->pl_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); spin_unlock_rd(&limit->p_spin); return (0); } /* * Duplicate a file descriptor to a particular value. * * note: keep in mind that a potential race condition exists when closing * descriptors from a shared descriptor table (via rfork). * * MPSAFE */ int sys_dup2(struct dup2_args *uap) { int error; error = kern_dup(DUP_FIXED, uap->from, uap->to, uap->sysmsg_fds); return (error); } /* * Duplicate a file descriptor. * * MPSAFE */ int sys_dup(struct dup_args *uap) { int error; error = kern_dup(DUP_VARIABLE, uap->fd, 0, uap->sysmsg_fds); return (error); } /* * MPALMOSTSAFE - acquires mplock for fp operations */ int kern_fcntl(int fd, int cmd, union fcntl_dat *dat, struct ucred *cred) { struct thread *td = curthread; struct proc *p = td->td_proc; struct file *fp; struct vnode *vp; u_int newmin; u_int oflags; int tmp, error, flg = F_POSIX; KKASSERT(p); /* * Operations on file descriptors that do not require a file pointer. */ switch (cmd) { case F_GETFD: error = fgetfdflags(p->p_fd, fd, &tmp); if (error == 0) dat->fc_cloexec = (tmp & UF_EXCLOSE) ? FD_CLOEXEC : 0; return (error); case F_SETFD: if (dat->fc_cloexec & FD_CLOEXEC) error = fsetfdflags(p->p_fd, fd, UF_EXCLOSE); else error = fclrfdflags(p->p_fd, fd, UF_EXCLOSE); return (error); case F_DUPFD: newmin = dat->fc_fd; error = kern_dup(DUP_VARIABLE, fd, newmin, &dat->fc_fd); return (error); default: break; } /* * Operations on file pointers */ if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) return (EBADF); get_mplock(); switch (cmd) { case F_GETFL: dat->fc_flags = OFLAGS(fp->f_flag); error = 0; break; case F_SETFL: oflags = fp->f_flag & FCNTLFLAGS; fp->f_flag &= ~FCNTLFLAGS; fp->f_flag |= FFLAGS(dat->fc_flags & ~O_ACCMODE) & FCNTLFLAGS; error = 0; if ((fp->f_flag ^ oflags) & FASYNC) { tmp = fp->f_flag & FASYNC; error = fo_ioctl(fp, FIOASYNC, (caddr_t)&tmp, cred); } if (error) fp->f_flag = (fp->f_flag & ~FCNTLFLAGS) | oflags; break; case F_GETOWN: error = fo_ioctl(fp, FIOGETOWN, (caddr_t)&dat->fc_owner, cred); break; case F_SETOWN: error = fo_ioctl(fp, FIOSETOWN, (caddr_t)&dat->fc_owner, cred); break; case F_SETLKW: flg |= F_WAIT; /* Fall into F_SETLK */ case F_SETLK: if (fp->f_type != DTYPE_VNODE) { error = EBADF; break; } vp = (struct vnode *)fp->f_data; /* * copyin/lockop may block */ if (dat->fc_flock.l_whence == SEEK_CUR) dat->fc_flock.l_start += fp->f_offset; switch (dat->fc_flock.l_type) { case F_RDLCK: if ((fp->f_flag & FREAD) == 0) { error = EBADF; break; } p->p_leader->p_flag |= P_ADVLOCK; error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, &dat->fc_flock, flg); break; case F_WRLCK: if ((fp->f_flag & FWRITE) == 0) { error = EBADF; break; } p->p_leader->p_flag |= P_ADVLOCK; error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_SETLK, &dat->fc_flock, flg); break; case F_UNLCK: error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, &dat->fc_flock, F_POSIX); break; default: error = EINVAL; break; } /* * It is possible to race a close() on the descriptor while * we were blocked getting the lock. If this occurs the * close might not have caught the lock. */ if (checkfpclosed(p->p_fd, fd, fp)) { dat->fc_flock.l_whence = SEEK_SET; dat->fc_flock.l_start = 0; dat->fc_flock.l_len = 0; dat->fc_flock.l_type = F_UNLCK; (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, &dat->fc_flock, F_POSIX); } break; case F_GETLK: if (fp->f_type != DTYPE_VNODE) { error = EBADF; break; } vp = (struct vnode *)fp->f_data; /* * copyin/lockop may block */ if (dat->fc_flock.l_type != F_RDLCK && dat->fc_flock.l_type != F_WRLCK && dat->fc_flock.l_type != F_UNLCK) { error = EINVAL; break; } if (dat->fc_flock.l_whence == SEEK_CUR) dat->fc_flock.l_start += fp->f_offset; error = VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_GETLK, &dat->fc_flock, F_POSIX); break; default: error = EINVAL; break; } rel_mplock(); fdrop(fp); return (error); } /* * The file control system call. * * MPSAFE */ int sys_fcntl(struct fcntl_args *uap) { union fcntl_dat dat; int error; switch (uap->cmd) { case F_DUPFD: dat.fc_fd = uap->arg; break; case F_SETFD: dat.fc_cloexec = uap->arg; break; case F_SETFL: dat.fc_flags = uap->arg; break; case F_SETOWN: dat.fc_owner = uap->arg; break; case F_SETLKW: case F_SETLK: case F_GETLK: error = copyin((caddr_t)uap->arg, &dat.fc_flock, sizeof(struct flock)); if (error) return (error); break; } error = kern_fcntl(uap->fd, uap->cmd, &dat, curproc->p_ucred); if (error == 0) { switch (uap->cmd) { case F_DUPFD: uap->sysmsg_result = dat.fc_fd; break; case F_GETFD: uap->sysmsg_result = dat.fc_cloexec; break; case F_GETFL: uap->sysmsg_result = dat.fc_flags; break; case F_GETOWN: uap->sysmsg_result = dat.fc_owner; case F_GETLK: error = copyout(&dat.fc_flock, (caddr_t)uap->arg, sizeof(struct flock)); break; } } return (error); } /* * Common code for dup, dup2, and fcntl(F_DUPFD). * * The type flag can be either DUP_FIXED or DUP_VARIABLE. DUP_FIXED tells * kern_dup() to destructively dup over an existing file descriptor if new * is already open. DUP_VARIABLE tells kern_dup() to find the lowest * unused file descriptor that is greater than or equal to new. * * MPSAFE */ int kern_dup(enum dup_type type, int old, int new, int *res) { struct thread *td = curthread; struct proc *p = td->td_proc; struct filedesc *fdp = p->p_fd; struct file *fp; struct file *delfp; int oldflags; int holdleaders; int error, newfd; /* * Verify that we have a valid descriptor to dup from and * possibly to dup to. */ retry: spin_lock_wr(&fdp->fd_spin); if (new < 0 || new > p->p_rlimit[RLIMIT_NOFILE].rlim_cur || new >= maxfilesperproc) { spin_unlock_wr(&fdp->fd_spin); return (EINVAL); } if ((unsigned)old >= fdp->fd_nfiles || fdp->fd_files[old].fp == NULL) { spin_unlock_wr(&fdp->fd_spin); return (EBADF); } if (type == DUP_FIXED && old == new) { *res = new; spin_unlock_wr(&fdp->fd_spin); return (0); } fp = fdp->fd_files[old].fp; oldflags = fdp->fd_files[old].fileflags; fhold(fp); /* MPSAFE - can be called with a spinlock held */ /* * Allocate a new descriptor if DUP_VARIABLE, or expand the table * if the requested descriptor is beyond the current table size. * * This can block. Retry if the source descriptor no longer matches * or if our expectation in the expansion case races. * * If we are not expanding or allocating a new decriptor, then reset * the target descriptor to a reserved state so we have a uniform * setup for the next code block. */ if (type == DUP_VARIABLE || new >= fdp->fd_nfiles) { spin_unlock_wr(&fdp->fd_spin); error = fdalloc(p, new, &newfd); spin_lock_wr(&fdp->fd_spin); if (error) { spin_unlock_wr(&fdp->fd_spin); fdrop(fp); return (error); } /* * Check for ripout */ if (old >= fdp->fd_nfiles || fdp->fd_files[old].fp != fp) { fsetfd_locked(fdp, NULL, newfd); spin_unlock_wr(&fdp->fd_spin); fdrop(fp); goto retry; } /* * Check for expansion race */ if (type != DUP_VARIABLE && new != newfd) { fsetfd_locked(fdp, NULL, newfd); spin_unlock_wr(&fdp->fd_spin); fdrop(fp); goto retry; } /* * Check for ripout, newfd reused old (this case probably * can't occur). */ if (old == newfd) { fsetfd_locked(fdp, NULL, newfd); spin_unlock_wr(&fdp->fd_spin); fdrop(fp); goto retry; } new = newfd; delfp = NULL; } else { if (fdp->fd_files[new].reserved) { spin_unlock_wr(&fdp->fd_spin); fdrop(fp); kprintf("Warning: dup(): target descriptor %d is reserved, waiting for it to be resolved\n", new); tsleep(fdp, 0, "fdres", hz); goto retry; } /* * If the target descriptor was never allocated we have * to allocate it. If it was we have to clean out the * old descriptor. delfp inherits the ref from the * descriptor table. */ delfp = fdp->fd_files[new].fp; fdp->fd_files[new].fp = NULL; fdp->fd_files[new].reserved = 1; if (delfp == NULL) { fdreserve_locked(fdp, new, 1); if (new > fdp->fd_lastfile) fdp->fd_lastfile = new; } } /* * NOTE: still holding an exclusive spinlock */ /* * If a descriptor is being overwritten we may hve to tell * fdfree() to sleep to ensure that all relevant process * leaders can be traversed in closef(). */ if (delfp != NULL && p->p_fdtol != NULL) { fdp->fd_holdleaderscount++; holdleaders = 1; } else { holdleaders = 0; } KASSERT(delfp == NULL || type == DUP_FIXED, ("dup() picked an open file")); /* * Duplicate the source descriptor, update lastfile. If the new * descriptor was not allocated and we aren't replacing an existing * descriptor we have to mark the descriptor as being in use. * * The fd_files[] array inherits fp's hold reference. */ fsetfd_locked(fdp, fp, new); fdp->fd_files[new].fileflags = oldflags & ~UF_EXCLOSE; spin_unlock_wr(&fdp->fd_spin); fdrop(fp); *res = new; /* * If we dup'd over a valid file, we now own the reference to it * and must dispose of it using closef() semantics (as if a * close() were performed on it). */ if (delfp) { (void)closef(delfp, td); if (holdleaders) { spin_lock_wr(&fdp->fd_spin); fdp->fd_holdleaderscount--; if (fdp->fd_holdleaderscount == 0 && fdp->fd_holdleaderswakeup != 0) { fdp->fd_holdleaderswakeup = 0; spin_unlock_wr(&fdp->fd_spin); wakeup(&fdp->fd_holdleaderscount); } else { spin_unlock_wr(&fdp->fd_spin); } } } return (0); } /* * If sigio is on the list associated with a process or process group, * disable signalling from the device, remove sigio from the list and * free sigio. */ void funsetown(struct sigio *sigio) { if (sigio == NULL) return; crit_enter(); *(sigio->sio_myref) = NULL; crit_exit(); if (sigio->sio_pgid < 0) { SLIST_REMOVE(&sigio->sio_pgrp->pg_sigiolst, sigio, sigio, sio_pgsigio); } else /* if ((*sigiop)->sio_pgid > 0) */ { SLIST_REMOVE(&sigio->sio_proc->p_sigiolst, sigio, sigio, sio_pgsigio); } crfree(sigio->sio_ucred); kfree(sigio, M_SIGIO); } /* Free a list of sigio structures. */ void funsetownlst(struct sigiolst *sigiolst) { struct sigio *sigio; while ((sigio = SLIST_FIRST(sigiolst)) != NULL) funsetown(sigio); } /* * This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg). * * After permission checking, add a sigio structure to the sigio list for * the process or process group. */ int fsetown(pid_t pgid, struct sigio **sigiop) { struct proc *proc; struct pgrp *pgrp; struct sigio *sigio; if (pgid == 0) { funsetown(*sigiop); return (0); } if (pgid > 0) { proc = pfind(pgid); if (proc == NULL) return (ESRCH); /* * Policy - Don't allow a process to FSETOWN a process * in another session. * * Remove this test to allow maximum flexibility or * restrict FSETOWN to the current process or process * group for maximum safety. */ if (proc->p_session != curproc->p_session) return (EPERM); pgrp = NULL; } else /* if (pgid < 0) */ { pgrp = pgfind(-pgid); if (pgrp == NULL) return (ESRCH); /* * Policy - Don't allow a process to FSETOWN a process * in another session. * * Remove this test to allow maximum flexibility or * restrict FSETOWN to the current process or process * group for maximum safety. */ if (pgrp->pg_session != curproc->p_session) return (EPERM); proc = NULL; } funsetown(*sigiop); sigio = kmalloc(sizeof(struct sigio), M_SIGIO, M_WAITOK); if (pgid > 0) { SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio); sigio->sio_proc = proc; } else { SLIST_INSERT_HEAD(&pgrp->pg_sigiolst, sigio, sio_pgsigio); sigio->sio_pgrp = pgrp; } sigio->sio_pgid = pgid; sigio->sio_ucred = crhold(curproc->p_ucred); /* It would be convenient if p_ruid was in ucred. */ sigio->sio_ruid = curproc->p_ucred->cr_ruid; sigio->sio_myref = sigiop; crit_enter(); *sigiop = sigio; crit_exit(); return (0); } /* * This is common code for FIOGETOWN ioctl called by fcntl(fd, F_GETOWN, arg). */ pid_t fgetown(struct sigio *sigio) { return (sigio != NULL ? sigio->sio_pgid : 0); } /* * Close many file descriptors. * * MPSAFE */ int sys_closefrom(struct closefrom_args *uap) { return(kern_closefrom(uap->fd)); } /* * Close all file descriptors greater then or equal to fd * * MPSAFE */ int kern_closefrom(int fd) { struct thread *td = curthread; struct proc *p = td->td_proc; struct filedesc *fdp; KKASSERT(p); fdp = p->p_fd; if (fd < 0) return (EINVAL); /* * NOTE: This function will skip unassociated descriptors and * reserved descriptors that have not yet been assigned. * fd_lastfile can change as a side effect of kern_close(). */ spin_lock_wr(&fdp->fd_spin); while (fd <= fdp->fd_lastfile) { if (fdp->fd_files[fd].fp != NULL) { spin_unlock_wr(&fdp->fd_spin); /* ok if this races another close */ if (kern_close(fd) == EINTR) return (EINTR); spin_lock_wr(&fdp->fd_spin); } ++fd; } spin_unlock_wr(&fdp->fd_spin); return (0); } /* * Close a file descriptor. * * MPSAFE */ int sys_close(struct close_args *uap) { return(kern_close(uap->fd)); } /* * MPALMOSTSAFE - acquires mplock around knote_fdclose() calls */ int kern_close(int fd) { struct thread *td = curthread; struct proc *p = td->td_proc; struct filedesc *fdp; struct file *fp; int error; int holdleaders; KKASSERT(p); fdp = p->p_fd; spin_lock_wr(&fdp->fd_spin); if ((fp = funsetfd_locked(fdp, fd)) == NULL) { spin_unlock_wr(&fdp->fd_spin); return (EBADF); } holdleaders = 0; if (p->p_fdtol != NULL) { /* * Ask fdfree() to sleep to ensure that all relevant * process leaders can be traversed in closef(). */ fdp->fd_holdleaderscount++; holdleaders = 1; } /* * we now hold the fp reference that used to be owned by the descriptor * array. */ spin_unlock_wr(&fdp->fd_spin); if (fd < fdp->fd_knlistsize) { get_mplock(); if (fd < fdp->fd_knlistsize) knote_fdclose(p, fd); rel_mplock(); } error = closef(fp, td); if (holdleaders) { spin_lock_wr(&fdp->fd_spin); fdp->fd_holdleaderscount--; if (fdp->fd_holdleaderscount == 0 && fdp->fd_holdleaderswakeup != 0) { fdp->fd_holdleaderswakeup = 0; spin_unlock_wr(&fdp->fd_spin); wakeup(&fdp->fd_holdleaderscount); } else { spin_unlock_wr(&fdp->fd_spin); } } return (error); } /* * shutdown_args(int fd, int how) */ int kern_shutdown(int fd, int how) { struct thread *td = curthread; struct proc *p = td->td_proc; struct file *fp; int error; KKASSERT(p); if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) return (EBADF); error = fo_shutdown(fp, how); fdrop(fp); return (error); } int sys_shutdown(struct shutdown_args *uap) { int error; error = kern_shutdown(uap->s, uap->how); return (error); } int kern_fstat(int fd, struct stat *ub) { struct thread *td = curthread; struct proc *p = td->td_proc; struct file *fp; int error; KKASSERT(p); if ((fp = holdfp(p->p_fd, fd, -1)) == NULL) return (EBADF); error = fo_stat(fp, ub, p->p_ucred); fdrop(fp); return (error); } /* * Return status information about a file descriptor. */ int sys_fstat(struct fstat_args *uap) { struct stat st; int error; error = kern_fstat(uap->fd, &st); if (error == 0) error = copyout(&st, uap->sb, sizeof(st)); return (error); } /* * Return pathconf information about a file descriptor. */ /* ARGSUSED */ int sys_fpathconf(struct fpathconf_args *uap) { struct thread *td = curthread; struct proc *p = td->td_proc; struct file *fp; struct vnode *vp; int error = 0; KKASSERT(p); if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL) return (EBADF); switch (fp->f_type) { case DTYPE_PIPE: case DTYPE_SOCKET: if (uap->name != _PC_PIPE_BUF) { error = EINVAL; } else { uap->sysmsg_result = PIPE_BUF; error = 0; } break; case DTYPE_FIFO: case DTYPE_VNODE: vp = (struct vnode *)fp->f_data; error = VOP_PATHCONF(vp, uap->name, uap->sysmsg_fds); break; default: error = EOPNOTSUPP; break; } fdrop(fp); return(error); } static int fdexpand; SYSCTL_INT(_debug, OID_AUTO, fdexpand, CTLFLAG_RD, &fdexpand, 0, ""); /* * Grow the file table so it can hold through descriptor (want). * * The fdp's spinlock must be held exclusively on entry and may be held * exclusively on return. The spinlock may be cycled by the routine. * * MPSAFE */ static void fdgrow_locked(struct filedesc *fdp, int want) { struct fdnode *newfiles; struct fdnode *oldfiles; int nf, extra; nf = fdp->fd_nfiles; do { /* nf has to be of the form 2^n - 1 */ nf = 2 * nf + 1; } while (nf <= want); spin_unlock_wr(&fdp->fd_spin); newfiles = kmalloc(nf * sizeof(struct fdnode), M_FILEDESC, M_WAITOK); spin_lock_wr(&fdp->fd_spin); /* * We could have raced another extend while we were not holding * the spinlock. */ if (fdp->fd_nfiles >= nf) { spin_unlock_wr(&fdp->fd_spin); kfree(newfiles, M_FILEDESC); spin_lock_wr(&fdp->fd_spin); return; } /* * Copy the existing ofile and ofileflags arrays * and zero the new portion of each array. */ extra = nf - fdp->fd_nfiles; bcopy(fdp->fd_files, newfiles, fdp->fd_nfiles * sizeof(struct fdnode)); bzero(&newfiles[fdp->fd_nfiles], extra * sizeof(struct fdnode)); oldfiles = fdp->fd_files; fdp->fd_files = newfiles; fdp->fd_nfiles = nf; if (oldfiles != fdp->fd_builtin_files) { spin_unlock_wr(&fdp->fd_spin); kfree(oldfiles, M_FILEDESC); spin_lock_wr(&fdp->fd_spin); } fdexpand++; } /* * Number of nodes in right subtree, including the root. */ static __inline int right_subtree_size(int n) { return (n ^ (n | (n + 1))); } /* * Bigger ancestor. */ static __inline int right_ancestor(int n) { return (n | (n + 1)); } /* * Smaller ancestor. */ static __inline int left_ancestor(int n) { return ((n & (n + 1)) - 1); } /* * Traverse the in-place binary tree buttom-up adjusting the allocation * count so scans can determine where free descriptors are located. * * MPSAFE - caller must be holding an exclusive spinlock on fdp */ static void fdreserve_locked(struct filedesc *fdp, int fd, int incr) { while (fd >= 0) { fdp->fd_files[fd].allocated += incr; KKASSERT(fdp->fd_files[fd].allocated >= 0); fd = left_ancestor(fd); } } /* * Reserve a file descriptor for the process. If no error occurs, the * caller MUST at some point call fsetfd() or assign a file pointer * or dispose of the reservation. * * MPSAFE */ int fdalloc(struct proc *p, int want, int *result) { struct filedesc *fdp = p->p_fd; int fd, rsize, rsum, node, lim; spin_lock_rd(&p->p_limit->p_spin); lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); spin_unlock_rd(&p->p_limit->p_spin); if (want >= lim) return (EMFILE); spin_lock_wr(&fdp->fd_spin); if (want >= fdp->fd_nfiles) fdgrow_locked(fdp, want); /* * Search for a free descriptor starting at the higher * of want or fd_freefile. If that fails, consider * expanding the ofile array. * * NOTE! the 'allocated' field is a cumulative recursive allocation * count. If we happen to see a value of 0 then we can shortcut * our search. Otherwise we run through through the tree going * down branches we know have free descriptor(s) until we hit a * leaf node. The leaf node will be free but will not necessarily * have an allocated field of 0. */ retry: /* move up the tree looking for a subtree with a free node */ for (fd = max(want, fdp->fd_freefile); fd < min(fdp->fd_nfiles, lim); fd = right_ancestor(fd)) { if (fdp->fd_files[fd].allocated == 0) goto found; rsize = right_subtree_size(fd); if (fdp->fd_files[fd].allocated == rsize) continue; /* right subtree full */ /* * Free fd is in the right subtree of the tree rooted at fd. * Call that subtree R. Look for the smallest (leftmost) * subtree of R with an unallocated fd: continue moving * down the left branch until encountering a full left * subtree, then move to the right. */ for (rsum = 0, rsize /= 2; rsize > 0; rsize /= 2) { node = fd + rsize; rsum += fdp->fd_files[node].allocated; if (fdp->fd_files[fd].allocated == rsum + rsize) { fd = node; /* move to the right */ if (fdp->fd_files[node].allocated == 0) goto found; rsum = 0; } } goto found; } /* * No space in current array. Expand? */ if (fdp->fd_nfiles >= lim) { spin_unlock_wr(&fdp->fd_spin); return (EMFILE); } fdgrow_locked(fdp, want); goto retry; found: KKASSERT(fd < fdp->fd_nfiles); if (fd > fdp->fd_lastfile) fdp->fd_lastfile = fd; if (want <= fdp->fd_freefile) fdp->fd_freefile = fd; *result = fd; KKASSERT(fdp->fd_files[fd].fp == NULL); KKASSERT(fdp->fd_files[fd].reserved == 0); fdp->fd_files[fd].fileflags = 0; fdp->fd_files[fd].reserved = 1; fdreserve_locked(fdp, fd, 1); spin_unlock_wr(&fdp->fd_spin); return (0); } /* * Check to see whether n user file descriptors * are available to the process p. * * MPSAFE */ int fdavail(struct proc *p, int n) { struct filedesc *fdp = p->p_fd; struct fdnode *fdnode; int i, lim, last; spin_lock_rd(&p->p_limit->p_spin); lim = min((int)p->p_rlimit[RLIMIT_NOFILE].rlim_cur, maxfilesperproc); spin_unlock_rd(&p->p_limit->p_spin); spin_lock_rd(&fdp->fd_spin); if ((i = lim - fdp->fd_nfiles) > 0 && (n -= i) <= 0) { spin_unlock_rd(&fdp->fd_spin); return (1); } last = min(fdp->fd_nfiles, lim); fdnode = &fdp->fd_files[fdp->fd_freefile]; for (i = last - fdp->fd_freefile; --i >= 0; ++fdnode) { if (fdnode->fp == NULL && --n <= 0) { spin_unlock_rd(&fdp->fd_spin); return (1); } } spin_unlock_rd(&fdp->fd_spin); return (0); } /* * falloc: * Create a new open file structure and reserve a file decriptor * for the process that refers to it. * * Root creds are checked using p, or assumed if p is NULL. If * resultfd is non-NULL then p must also be non-NULL. No file * descriptor is reserved if resultfd is NULL. * * A file pointer with a refcount of 1 is returned. Note that the * file pointer is NOT associated with the descriptor. If falloc * returns success, fsetfd() MUST be called to either associate the * file pointer or clear the reservation. * * MPSAFE */ int falloc(struct proc *p, struct file **resultfp, int *resultfd) { static struct timeval lastfail; static int curfail; struct file *fp; int error; fp = NULL; /* * Handle filetable full issues and root overfill. */ if (nfiles >= maxfiles - maxfilesrootres && ((p && p->p_ucred->cr_ruid != 0) || nfiles >= maxfiles)) { if (ppsratecheck(&lastfail, &curfail, 1)) { kprintf("kern.maxfiles limit exceeded by uid %d, please see tuning(7).\n", (p ? p->p_ucred->cr_ruid : -1)); } error = ENFILE; goto done; } /* * Allocate a new file descriptor. */ fp = kmalloc(sizeof(struct file), M_FILE, M_WAITOK | M_ZERO); spin_init(&fp->f_spin); fp->f_count = 1; fp->f_ops = &badfileops; fp->f_seqcount = 1; if (p) fp->f_cred = crhold(p->p_ucred); else fp->f_cred = crhold(proc0.p_ucred); spin_lock_wr(&filehead_spin); nfiles++; LIST_INSERT_HEAD(&filehead, fp, f_list); spin_unlock_wr(&filehead_spin); if (resultfd) { if ((error = fdalloc(p, 0, resultfd)) != 0) { fdrop(fp); fp = NULL; } } else { error = 0; } done: *resultfp = fp; return (error); } /* * MPSAFE */ static int checkfpclosed(struct filedesc *fdp, int fd, struct file *fp) { int error; spin_lock_rd(&fdp->fd_spin); if ((unsigned) fd >= fdp->fd_nfiles || fp != fdp->fd_files[fd].fp) error = EBADF; else error = 0; spin_unlock_rd(&fdp->fd_spin); return (error); } /* * Associate a file pointer with a previously reserved file descriptor. * This function always succeeds. * * If fp is NULL, the file descriptor is returned to the pool. */ /* * MPSAFE (exclusive spinlock must be held on call) */ static void fsetfd_locked(struct filedesc *fdp, struct file *fp, int fd) { KKASSERT((unsigned)fd < fdp->fd_nfiles); KKASSERT(fdp->fd_files[fd].reserved != 0); if (fp) { fhold(fp); fdp->fd_files[fd].fp = fp; fdp->fd_files[fd].reserved = 0; if (fp->f_type == DTYPE_KQUEUE) { if (fdp->fd_knlistsize < 0) fdp->fd_knlistsize = 0; } } else { fdp->fd_files[fd].reserved = 0; fdreserve_locked(fdp, fd, -1); fdfixup_locked(fdp, fd); } } /* * MPSAFE */ void fsetfd(struct proc *p, struct file *fp, int fd) { struct filedesc *fdp = p->p_fd; spin_lock_wr(&fdp->fd_spin); fsetfd_locked(fdp, fp, fd); spin_unlock_wr(&fdp->fd_spin); } /* * MPSAFE (exclusive spinlock must be held on call) */ static struct file * funsetfd_locked(struct filedesc *fdp, int fd) { struct file *fp; if ((unsigned)fd >= fdp->fd_nfiles) return (NULL); if ((fp = fdp->fd_files[fd].fp) == NULL) return (NULL); fdp->fd_files[fd].fp = NULL; fdp->fd_files[fd].fileflags = 0; fdreserve_locked(fdp, fd, -1); fdfixup_locked(fdp, fd); return(fp); } /* * MPSAFE */ int fgetfdflags(struct filedesc *fdp, int fd, int *flagsp) { int error; spin_lock_rd(&fdp->fd_spin); if (((u_int)fd) >= fdp->fd_nfiles) { error = EBADF; } else if (fdp->fd_files[fd].fp == NULL) { error = EBADF; } else { *flagsp = fdp->fd_files[fd].fileflags; error = 0; } spin_unlock_rd(&fdp->fd_spin); return (error); } /* * MPSAFE */ int fsetfdflags(struct filedesc *fdp, int fd, int add_flags) { int error; spin_lock_wr(&fdp->fd_spin); if (((u_int)fd) >= fdp->fd_nfiles) { error = EBADF; } else if (fdp->fd_files[fd].fp == NULL) { error = EBADF; } else { fdp->fd_files[fd].fileflags |= add_flags; error = 0; } spin_unlock_wr(&fdp->fd_spin); return (error); } /* * MPSAFE */ int fclrfdflags(struct filedesc *fdp, int fd, int rem_flags) { int error; spin_lock_wr(&fdp->fd_spin); if (((u_int)fd) >= fdp->fd_nfiles) { error = EBADF; } else if (fdp->fd_files[fd].fp == NULL) { error = EBADF; } else { fdp->fd_files[fd].fileflags &= ~rem_flags; error = 0; } spin_unlock_wr(&fdp->fd_spin); return (error); } void fsetcred(struct file *fp, struct ucred *cr) { crhold(cr); crfree(fp->f_cred); fp->f_cred = cr; } /* * Free a file descriptor. */ static void ffree(struct file *fp) { KASSERT((fp->f_count == 0), ("ffree: fp_fcount not 0!")); spin_lock_wr(&filehead_spin); LIST_REMOVE(fp, f_list); nfiles--; spin_unlock_wr(&filehead_spin); crfree(fp->f_cred); if (fp->f_nchandle.ncp) cache_drop(&fp->f_nchandle); kfree(fp, M_FILE); } /* * called from init_main, initialize filedesc0 for proc0. */ void fdinit_bootstrap(struct proc *p0, struct filedesc *fdp0, int cmask) { p0->p_fd = fdp0; p0->p_fdtol = NULL; fdp0->fd_refcnt = 1; fdp0->fd_cmask = cmask; fdp0->fd_files = fdp0->fd_builtin_files; fdp0->fd_nfiles = NDFILE; fdp0->fd_lastfile = -1; spin_init(&fdp0->fd_spin); } /* * Build a new filedesc structure. * * NOT MPSAFE (vref) */ struct filedesc * fdinit(struct proc *p) { struct filedesc *newfdp; struct filedesc *fdp = p->p_fd; newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK|M_ZERO); spin_lock_rd(&fdp->fd_spin); if (fdp->fd_cdir) { newfdp->fd_cdir = fdp->fd_cdir; vref(newfdp->fd_cdir); cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir); } /* * rdir may not be set in e.g. proc0 or anything vm_fork'd off of * proc0, but should unconditionally exist in other processes. */ if (fdp->fd_rdir) { newfdp->fd_rdir = fdp->fd_rdir; vref(newfdp->fd_rdir); cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir); } if (fdp->fd_jdir) { newfdp->fd_jdir = fdp->fd_jdir; vref(newfdp->fd_jdir); cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir); } spin_unlock_rd(&fdp->fd_spin); /* Create the file descriptor table. */ newfdp->fd_refcnt = 1; newfdp->fd_cmask = cmask; newfdp->fd_files = newfdp->fd_builtin_files; newfdp->fd_nfiles = NDFILE; newfdp->fd_knlistsize = -1; newfdp->fd_lastfile = -1; spin_init(&newfdp->fd_spin); return (newfdp); } /* * Share a filedesc structure. * * MPSAFE */ struct filedesc * fdshare(struct proc *p) { struct filedesc *fdp; fdp = p->p_fd; spin_lock_wr(&fdp->fd_spin); fdp->fd_refcnt++; spin_unlock_wr(&fdp->fd_spin); return (fdp); } /* * Copy a filedesc structure. * * MPSAFE */ struct filedesc * fdcopy(struct proc *p) { struct filedesc *fdp = p->p_fd; struct filedesc *newfdp; struct fdnode *fdnode; int i; int ni; /* * Certain daemons might not have file descriptors. */ if (fdp == NULL) return (NULL); /* * Allocate the new filedesc and fd_files[] array. This can race * with operations by other threads on the fdp so we have to be * careful. */ newfdp = kmalloc(sizeof(struct filedesc), M_FILEDESC, M_WAITOK | M_ZERO); again: spin_lock_rd(&fdp->fd_spin); if (fdp->fd_lastfile < NDFILE) { newfdp->fd_files = newfdp->fd_builtin_files; i = NDFILE; } else { /* * We have to allocate (N^2-1) entries for our in-place * binary tree. Allow the table to shrink. */ i = fdp->fd_nfiles; ni = (i - 1) / 2; while (ni > fdp->fd_lastfile && ni > NDFILE) { i = ni; ni = (i - 1) / 2; } spin_unlock_rd(&fdp->fd_spin); newfdp->fd_files = kmalloc(i * sizeof(struct fdnode), M_FILEDESC, M_WAITOK | M_ZERO); /* * Check for race, retry */ spin_lock_rd(&fdp->fd_spin); if (i <= fdp->fd_lastfile) { spin_unlock_rd(&fdp->fd_spin); kfree(newfdp->fd_files, M_FILEDESC); goto again; } } /* * Dup the remaining fields. vref() and cache_hold() can be * safely called while holding the read spinlock on fdp. * * The read spinlock on fdp is still being held. * * NOTE: vref and cache_hold calls for the case where the vnode * or cache entry already has at least one ref may be called * while holding spin locks. */ if ((newfdp->fd_cdir = fdp->fd_cdir) != NULL) { vref(newfdp->fd_cdir); cache_copy(&fdp->fd_ncdir, &newfdp->fd_ncdir); } /* * We must check for fd_rdir here, at least for now because * the init process is created before we have access to the * rootvode to take a reference to it. */ if ((newfdp->fd_rdir = fdp->fd_rdir) != NULL) { vref(newfdp->fd_rdir); cache_copy(&fdp->fd_nrdir, &newfdp->fd_nrdir); } if ((newfdp->fd_jdir = fdp->fd_jdir) != NULL) { vref(newfdp->fd_jdir); cache_copy(&fdp->fd_njdir, &newfdp->fd_njdir); } newfdp->fd_refcnt = 1; newfdp->fd_nfiles = i; newfdp->fd_lastfile = fdp->fd_lastfile; newfdp->fd_freefile = fdp->fd_freefile; newfdp->fd_cmask = fdp->fd_cmask; newfdp->fd_knlist = NULL; newfdp->fd_knlistsize = -1; newfdp->fd_knhash = NULL; newfdp->fd_knhashmask = 0; spin_init(&newfdp->fd_spin); /* * Copy the descriptor table through (i). This also copies the * allocation state. Then go through and ref the file pointers * and clean up any KQ descriptors. * * kq descriptors cannot be copied. Since we haven't ref'd the * copied files yet we can ignore the return value from funsetfd(). * * The read spinlock on fdp is still being held. */ bcopy(fdp->fd_files, newfdp->fd_files, i * sizeof(struct fdnode)); for (i = 0 ; i < newfdp->fd_nfiles; ++i) { fdnode = &newfdp->fd_files[i]; if (fdnode->reserved) { fdreserve_locked(newfdp, i, -1); fdnode->reserved = 0; fdfixup_locked(newfdp, i); } else if (fdnode->fp) { if (fdnode->fp->f_type == DTYPE_KQUEUE) { (void)funsetfd_locked(newfdp, i); } else { fhold(fdnode->fp); } } } spin_unlock_rd(&fdp->fd_spin); return (newfdp); } /* * Release a filedesc structure. * * NOT MPSAFE (MPSAFE for refs > 1, but the final cleanup code is not MPSAFE) */ void fdfree(struct proc *p) { /* Take any thread of p */ struct thread *td = LIST_FIRST(&p->p_lwps)->lwp_thread; struct filedesc *fdp = p->p_fd; struct fdnode *fdnode; int i; struct filedesc_to_leader *fdtol; struct file *fp; struct vnode *vp; struct flock lf; /* Certain daemons might not have file descriptors. */ if (fdp == NULL) return; /* * Severe messing around to follow */ spin_lock_wr(&fdp->fd_spin); /* Check for special need to clear POSIX style locks */ fdtol = p->p_fdtol; if (fdtol != NULL) { KASSERT(fdtol->fdl_refcount > 0, ("filedesc_to_refcount botch: fdl_refcount=%d", fdtol->fdl_refcount)); if (fdtol->fdl_refcount == 1 && (p->p_leader->p_flag & P_ADVLOCK) != 0) { for (i = 0; i <= fdp->fd_lastfile; ++i) { fdnode = &fdp->fd_files[i]; if (fdnode->fp == NULL || fdnode->fp->f_type != DTYPE_VNODE) { continue; } fp = fdnode->fp; fhold(fp); spin_unlock_wr(&fdp->fd_spin); lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; lf.l_type = F_UNLCK; vp = (struct vnode *)fp->f_data; (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, &lf, F_POSIX); fdrop(fp); spin_lock_wr(&fdp->fd_spin); } } retry: if (fdtol->fdl_refcount == 1) { if (fdp->fd_holdleaderscount > 0 && (p->p_leader->p_flag & P_ADVLOCK) != 0) { /* * close() or do_dup() has cleared a reference * in a shared file descriptor table. */ fdp->fd_holdleaderswakeup = 1; msleep(&fdp->fd_holdleaderscount, &fdp->fd_spin, 0, "fdlhold", 0); goto retry; } if (fdtol->fdl_holdcount > 0) { /* * Ensure that fdtol->fdl_leader * remains valid in closef(). */ fdtol->fdl_wakeup = 1; msleep(fdtol, &fdp->fd_spin, 0, "fdlhold", 0); goto retry; } } fdtol->fdl_refcount--; if (fdtol->fdl_refcount == 0 && fdtol->fdl_holdcount == 0) { fdtol->fdl_next->fdl_prev = fdtol->fdl_prev; fdtol->fdl_prev->fdl_next = fdtol->fdl_next; } else { fdtol = NULL; } p->p_fdtol = NULL; if (fdtol != NULL) { spin_unlock_wr(&fdp->fd_spin); kfree(fdtol, M_FILEDESC_TO_LEADER); spin_lock_wr(&fdp->fd_spin); } } if (--fdp->fd_refcnt > 0) { spin_unlock_wr(&fdp->fd_spin); return; } spin_unlock_wr(&fdp->fd_spin); /* * we are the last reference to the structure, we can * safely assume it will not change out from under us. */ for (i = 0; i <= fdp->fd_lastfile; ++i) { if (fdp->fd_files[i].fp) closef(fdp->fd_files[i].fp, td); } if (fdp->fd_files != fdp->fd_builtin_files) kfree(fdp->fd_files, M_FILEDESC); if (fdp->fd_cdir) { cache_drop(&fdp->fd_ncdir); vrele(fdp->fd_cdir); } if (fdp->fd_rdir) { cache_drop(&fdp->fd_nrdir); vrele(fdp->fd_rdir); } if (fdp->fd_jdir) { cache_drop(&fdp->fd_njdir); vrele(fdp->fd_jdir); } if (fdp->fd_knlist) kfree(fdp->fd_knlist, M_KQUEUE); if (fdp->fd_knhash) kfree(fdp->fd_knhash, M_KQUEUE); kfree(fdp, M_FILEDESC); } /* * Retrieve and reference the file pointer associated with a descriptor. * * MPSAFE */ struct file * holdfp(struct filedesc *fdp, int fd, int flag) { struct file* fp; spin_lock_rd(&fdp->fd_spin); if (((u_int)fd) >= fdp->fd_nfiles) { fp = NULL; goto done; } if ((fp = fdp->fd_files[fd].fp) == NULL) goto done; if ((fp->f_flag & flag) == 0 && flag != -1) { fp = NULL; goto done; } fhold(fp); done: spin_unlock_rd(&fdp->fd_spin); return (fp); } /* * holdsock() - load the struct file pointer associated * with a socket into *fpp. If an error occurs, non-zero * will be returned and *fpp will be set to NULL. * * MPSAFE */ int holdsock(struct filedesc *fdp, int fd, struct file **fpp) { struct file *fp; int error; spin_lock_rd(&fdp->fd_spin); if ((unsigned)fd >= fdp->fd_nfiles) { error = EBADF; fp = NULL; goto done; } if ((fp = fdp->fd_files[fd].fp) == NULL) { error = EBADF; goto done; } if (fp->f_type != DTYPE_SOCKET) { error = ENOTSOCK; goto done; } fhold(fp); error = 0; done: spin_unlock_rd(&fdp->fd_spin); *fpp = fp; return (error); } /* * Convert a user file descriptor to a held file pointer. * * MPSAFE */ int holdvnode(struct filedesc *fdp, int fd, struct file **fpp) { struct file *fp; int error; spin_lock_rd(&fdp->fd_spin); if ((unsigned)fd >= fdp->fd_nfiles) { error = EBADF; fp = NULL; goto done; } if ((fp = fdp->fd_files[fd].fp) == NULL) { error = EBADF; goto done; } if (fp->f_type != DTYPE_VNODE && fp->f_type != DTYPE_FIFO) { error = EINVAL; goto done; } fhold(fp); error = 0; done: spin_unlock_rd(&fdp->fd_spin); *fpp = fp; return (error); } /* * For setugid programs, we don't want to people to use that setugidness * to generate error messages which write to a file which otherwise would * otherwise be off-limits to the process. * * This is a gross hack to plug the hole. A better solution would involve * a special vop or other form of generalized access control mechanism. We * go ahead and just reject all procfs file systems accesses as dangerous. * * Since setugidsafety calls this only for fd 0, 1 and 2, this check is * sufficient. We also don't for check setugidness since we know we are. */ static int is_unsafe(struct file *fp) { if (fp->f_type == DTYPE_VNODE && ((struct vnode *)(fp->f_data))->v_tag == VT_PROCFS) return (1); return (0); } /* * Make this setguid thing safe, if at all possible. * * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose() */ void setugidsafety(struct proc *p) { /* Take any thread of p */ struct thread *td = LIST_FIRST(&p->p_lwps)->lwp_thread; struct filedesc *fdp = p->p_fd; int i; /* Certain daemons might not have file descriptors. */ if (fdp == NULL) return; /* * note: fdp->fd_files may be reallocated out from under us while * we are blocked in a close. Be careful! */ for (i = 0; i <= fdp->fd_lastfile; i++) { if (i > 2) break; if (fdp->fd_files[i].fp && is_unsafe(fdp->fd_files[i].fp)) { struct file *fp; if (i < fdp->fd_knlistsize) knote_fdclose(p, i); /* * NULL-out descriptor prior to close to avoid * a race while close blocks. */ if ((fp = funsetfd_locked(fdp, i)) != NULL) closef(fp, td); } } } /* * Close any files on exec? * * NOT MPSAFE - scans fdp without spinlocks, calls knote_fdclose() */ void fdcloseexec(struct proc *p) { /* Take any thread of p */ struct thread *td = LIST_FIRST(&p->p_lwps)->lwp_thread; struct filedesc *fdp = p->p_fd; int i; /* Certain daemons might not have file descriptors. */ if (fdp == NULL) return; /* * We cannot cache fd_files since operations may block and rip * them out from under us. */ for (i = 0; i <= fdp->fd_lastfile; i++) { if (fdp->fd_files[i].fp != NULL && (fdp->fd_files[i].fileflags & UF_EXCLOSE)) { struct file *fp; if (i < fdp->fd_knlistsize) knote_fdclose(p, i); /* * NULL-out descriptor prior to close to avoid * a race while close blocks. */ if ((fp = funsetfd_locked(fdp, i)) != NULL) closef(fp, td); } } } /* * It is unsafe for set[ug]id processes to be started with file * descriptors 0..2 closed, as these descriptors are given implicit * significance in the Standard C library. fdcheckstd() will create a * descriptor referencing /dev/null for each of stdin, stdout, and * stderr that is not already open. * * NOT MPSAFE - calls falloc, vn_open, etc */ int fdcheckstd(struct proc *p) { struct nlookupdata nd; struct filedesc *fdp; struct file *fp; register_t retval; int i, error, flags, devnull; fdp = p->p_fd; if (fdp == NULL) return (0); devnull = -1; error = 0; for (i = 0; i < 3; i++) { if (fdp->fd_files[i].fp != NULL) continue; if (devnull < 0) { if ((error = falloc(p, &fp, &devnull)) != 0) break; error = nlookup_init(&nd, "/dev/null", UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); flags = FREAD | FWRITE; if (error == 0) error = vn_open(&nd, fp, flags, 0); if (error == 0) fsetfd(p, fp, devnull); else fsetfd(p, NULL, devnull); fdrop(fp); nlookup_done(&nd); if (error) break; KKASSERT(i == devnull); } else { error = kern_dup(DUP_FIXED, devnull, i, &retval); if (error != 0) break; } } return (error); } /* * Internal form of close. * Decrement reference count on file structure. * Note: td and/or p may be NULL when closing a file * that was being passed in a message. * * MPALMOSTSAFE - acquires mplock for VOP operations */ int closef(struct file *fp, struct thread *td) { struct vnode *vp; struct flock lf; struct filedesc_to_leader *fdtol; struct proc *p; if (fp == NULL) return (0); if (td == NULL) { td = curthread; p = NULL; /* allow no proc association */ } else { p = td->td_proc; /* can also be NULL */ } /* * 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 (p != NULL && fp->f_type == DTYPE_VNODE && (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS) ) { get_mplock(); if ((p->p_leader->p_flag & P_ADVLOCK) != 0) { lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; lf.l_type = F_UNLCK; vp = (struct vnode *)fp->f_data; (void) VOP_ADVLOCK(vp, (caddr_t)p->p_leader, F_UNLCK, &lf, F_POSIX); } fdtol = p->p_fdtol; if (fdtol != NULL) { /* * Handle special case where file descriptor table * is shared between multiple process leaders. */ for (fdtol = fdtol->fdl_next; fdtol != p->p_fdtol; fdtol = fdtol->fdl_next) { if ((fdtol->fdl_leader->p_flag & P_ADVLOCK) == 0) continue; fdtol->fdl_holdcount++; lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; lf.l_type = F_UNLCK; vp = (struct vnode *)fp->f_data; (void) VOP_ADVLOCK(vp, (caddr_t)fdtol->fdl_leader, F_UNLCK, &lf, F_POSIX); fdtol->fdl_holdcount--; if (fdtol->fdl_holdcount == 0 && fdtol->fdl_wakeup != 0) { fdtol->fdl_wakeup = 0; wakeup(fdtol); } } } rel_mplock(); } return (fdrop(fp)); } /* * MPSAFE * * fhold() can only be called if f_count is already at least 1 (i.e. the * caller of fhold() already has a reference to the file pointer in some * manner or other). * * This is a rare case where callers are allowed to hold spinlocks, so * we can't ourselves. Since we are not obtaining the fp spinlock, * we have to use an atomic lock to interlock against fdrop(). */ void fhold(struct file *fp) { atomic_add_int(&fp->f_count, 1); } /* * A spinlock is required to handle 1->0 transitions on f_count. We have * to use atomic_sub_int so as not to race the atomic_add_int in fhold(). * * MPALMOSTSAFE - acquires mplock for final close sequence */ int fdrop(struct file *fp) { struct flock lf; struct vnode *vp; int error; spin_lock_wr(&fp->f_spin); atomic_subtract_int(&fp->f_count, 1); if (fp->f_count > 0) { spin_unlock_wr(&fp->f_spin); return (0); } spin_unlock_wr(&fp->f_spin); get_mplock(); /* * The last reference has gone away, we own the fp structure free * and clear. */ if (fp->f_count < 0) panic("fdrop: count < 0"); if ((fp->f_flag & FHASLOCK) && fp->f_type == DTYPE_VNODE && (((struct vnode *)fp->f_data)->v_flag & VMAYHAVELOCKS) ) { lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; lf.l_type = F_UNLCK; vp = (struct vnode *)fp->f_data; (void) VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0); } if (fp->f_ops != &badfileops) error = fo_close(fp); else error = 0; ffree(fp); rel_mplock(); return (error); } /* * Apply an advisory lock on a file descriptor. * * Just attempt to get a record lock of the requested type on * the entire file (l_whence = SEEK_SET, l_start = 0, l_len = 0). */ int sys_flock(struct flock_args *uap) { struct proc *p = curproc; struct file *fp; struct vnode *vp; struct flock lf; int error; if ((fp = holdfp(p->p_fd, uap->fd, -1)) == NULL) return (EBADF); if (fp->f_type != DTYPE_VNODE) { error = EOPNOTSUPP; goto done; } vp = (struct vnode *)fp->f_data; lf.l_whence = SEEK_SET; lf.l_start = 0; lf.l_len = 0; if (uap->how & LOCK_UN) { lf.l_type = F_UNLCK; fp->f_flag &= ~FHASLOCK; error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, 0); goto done; } if (uap->how & LOCK_EX) lf.l_type = F_WRLCK; else if (uap->how & LOCK_SH) lf.l_type = F_RDLCK; else { error = EBADF; goto done; } fp->f_flag |= FHASLOCK; if (uap->how & LOCK_NB) error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, 0); else error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_WAIT); done: fdrop(fp); return (error); } /* * 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. */ /* ARGSUSED */ static int fdopen(struct dev_open_args *ap) { thread_t td = curthread; KKASSERT(td->td_lwp != NULL); /* * XXX Kludge: set curlwp->lwp_dupfd to contain the value of the * the file descriptor being sought for duplication. The error * return ensures that the vnode for this device will be released * by vn_open. Open will detect this special error and take the * actions in dupfdopen below. Other callers of vn_open or VOP_OPEN * will simply report the error. */ td->td_lwp->lwp_dupfd = minor(ap->a_head.a_dev); return (ENODEV); } /* * The caller has reserved the file descriptor dfd for us. On success we * must fsetfd() it. On failure the caller will clean it up. * * NOT MPSAFE - isn't getting spinlocks, possibly other things */ int dupfdopen(struct proc *p, int dfd, int sfd, int mode, int error) { struct filedesc *fdp = p->p_fd; struct file *wfp; struct file *xfp; if ((wfp = holdfp(fdp, sfd, -1)) == NULL) return (EBADF); /* * There are two cases of interest here. * * For ENODEV simply dup sfd to file descriptor dfd and return. * * For ENXIO steal away the file structure from sfd and store it * dfd. sfd is effectively closed by this operation. * * Any other error code is just returned. */ switch (error) { case ENODEV: /* * Check that the mode the file is being opened for is a * subset of the mode of the existing descriptor. */ if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) return (EACCES); fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags; fsetfd(p, wfp, dfd); error = 0; break; case ENXIO: /* * Steal away the file pointer from dfd, and stuff it into indx. */ fdp->fd_files[dfd].fileflags = fdp->fd_files[sfd].fileflags; fsetfd(p, wfp, dfd); if ((xfp = funsetfd_locked(fdp, sfd)) != NULL) fdrop(xfp); KKASSERT(xfp == wfp); /* XXX MP RACE */ error = 0; break; default: break; } fdrop(wfp); return (error); } /* * NOT MPSAFE - I think these refer to a common file descriptor table * and we need to spinlock that to link fdtol in. */ struct filedesc_to_leader * filedesc_to_leader_alloc(struct filedesc_to_leader *old, struct proc *leader) { struct filedesc_to_leader *fdtol; fdtol = kmalloc(sizeof(struct filedesc_to_leader), M_FILEDESC_TO_LEADER, M_WAITOK); fdtol->fdl_refcount = 1; fdtol->fdl_holdcount = 0; fdtol->fdl_wakeup = 0; fdtol->fdl_leader = leader; if (old != NULL) { fdtol->fdl_next = old->fdl_next; fdtol->fdl_prev = old; old->fdl_next = fdtol; fdtol->fdl_next->fdl_prev = fdtol; } else { fdtol->fdl_next = fdtol; fdtol->fdl_prev = fdtol; } return fdtol; } /* * Scan all file pointers in the system. The callback is made with * both the master list spinlock held and the fp spinlock held, * both exclusively. * * MPSAFE * * WARNING: both the filehead spinlock and the file pointer spinlock are * held exclusively when the callback is made. The file pointer is not * referenced. */ void allfiles_scan_exclusive(int (*callback)(struct file *, void *), void *data) { struct file *fp; int res; spin_lock_wr(&filehead_spin); LIST_FOREACH(fp, &filehead, f_list) { spin_lock_wr(&fp->f_spin); res = callback(fp, data); spin_unlock_wr(&fp->f_spin); if (res < 0) break; } spin_unlock_wr(&filehead_spin); } /* * Get file structures. * * NOT MPSAFE - process list scan, SYSCTL_OUT (probably not mpsafe) */ struct sysctl_kern_file_info { int count; int error; struct sysctl_req *req; }; static int sysctl_kern_file_callback(struct proc *p, void *data); static int sysctl_kern_file(SYSCTL_HANDLER_ARGS) { struct sysctl_kern_file_info info; /* * Note: because the number of file descriptors is calculated * in different ways for sizing vs returning the data, * there is information leakage from the first loop. However, * it is of a similar order of magnitude to the leakage from * global system statistics such as kern.openfiles. * * When just doing a count, note that we cannot just count * the elements and add f_count via the filehead list because * threaded processes share their descriptor table and f_count might * still be '1' in that case. * * Since the SYSCTL op can block, we must hold the process to * prevent it being ripped out from under us either in the * file descriptor loop or in the greater LIST_FOREACH. The * process may be in varying states of disrepair. If the process * is in SZOMB we may have caught it just as it is being removed * from the allproc list, we must skip it in that case to maintain * an unbroken chain through the allproc list. */ info.count = 0; info.error = 0; info.req = req; allproc_scan(sysctl_kern_file_callback, &info); /* * When just calculating the size, overestimate a bit to try to * prevent system activity from causing the buffer-fill call * to fail later on. */ if (req->oldptr == NULL) { info.count = (info.count + 16) + (info.count / 10); info.error = SYSCTL_OUT(req, NULL, info.count * sizeof(struct kinfo_file)); } return (info.error); } static int sysctl_kern_file_callback(struct proc *p, void *data) { struct sysctl_kern_file_info *info = data; struct kinfo_file kf; struct filedesc *fdp; struct file *fp; uid_t uid; int n; if (p->p_stat == SIDL || (p->p_flag & P_ZOMBIE)) return(0); if (!PRISON_CHECK(info->req->td->td_proc->p_ucred, p->p_ucred) != 0) return(0); if ((fdp = p->p_fd) == NULL) return(0); spin_lock_rd(&fdp->fd_spin); for (n = 0; n < fdp->fd_nfiles; ++n) { if ((fp = fdp->fd_files[n].fp) == NULL) continue; if (info->req->oldptr == NULL) { ++info->count; } else { uid = p->p_ucred ? p->p_ucred->cr_uid : -1; kcore_make_file(&kf, fp, p->p_pid, uid, n); spin_unlock_rd(&fdp->fd_spin); info->error = SYSCTL_OUT(info->req, &kf, sizeof(kf)); spin_lock_rd(&fdp->fd_spin); if (info->error) break; } } spin_unlock_rd(&fdp->fd_spin); if (info->error) return(-1); return(0); } SYSCTL_PROC(_kern, KERN_FILE, file, CTLTYPE_OPAQUE|CTLFLAG_RD, 0, 0, sysctl_kern_file, "S,file", "Entire file table"); SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW, &maxfilesperproc, 0, "Maximum files allowed open per process"); SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW, &maxfiles, 0, "Maximum number of files"); SYSCTL_INT(_kern, OID_AUTO, maxfilesrootres, CTLFLAG_RW, &maxfilesrootres, 0, "Descriptors reserved for root use"); SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD, &nfiles, 0, "System-wide number of open files"); static void fildesc_drvinit(void *unused) { int fd; dev_ops_add(&fildesc_ops, 0, 0); for (fd = 0; fd < NUMFDESC; fd++) { make_dev(&fildesc_ops, fd, UID_BIN, GID_BIN, 0666, "fd/%d", fd); } make_dev(&fildesc_ops, 0, UID_ROOT, GID_WHEEL, 0666, "stdin"); make_dev(&fildesc_ops, 1, UID_ROOT, GID_WHEEL, 0666, "stdout"); make_dev(&fildesc_ops, 2, UID_ROOT, GID_WHEEL, 0666, "stderr"); } /* * MPSAFE */ struct fileops badfileops = { .fo_read = badfo_readwrite, .fo_write = badfo_readwrite, .fo_ioctl = badfo_ioctl, .fo_poll = badfo_poll, .fo_kqfilter = badfo_kqfilter, .fo_stat = badfo_stat, .fo_close = badfo_close, .fo_shutdown = badfo_shutdown }; /* * MPSAFE */ static int badfo_readwrite( struct file *fp, struct uio *uio, struct ucred *cred, int flags ) { return (EBADF); } /* * MPSAFE */ static int badfo_ioctl(struct file *fp, u_long com, caddr_t data, struct ucred *cred) { return (EBADF); } /* * MPSAFE */ static int badfo_poll(struct file *fp, int events, struct ucred *cred) { return (0); } /* * MPSAFE */ static int badfo_kqfilter(struct file *fp, struct knote *kn) { return (0); } static int badfo_stat(struct file *fp, struct stat *sb, struct ucred *cred) { return (EBADF); } /* * MPSAFE */ static int badfo_close(struct file *fp) { return (EBADF); } /* * MPSAFE */ static int badfo_shutdown(struct file *fp, int how) { return (EBADF); } /* * MPSAFE */ int nofo_shutdown(struct file *fp, int how) { return (EOPNOTSUPP); } SYSINIT(fildescdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR, fildesc_drvinit,NULL)