From c4f16b69e19b67a2eb94b3d505ea3c28322a8b59 Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Mon, 15 Jun 2009 20:38:55 +0000 Subject: [PATCH] Add a new 'void closefrom(int lowfd)' system call. When called, it closes any open file descriptors >= 'lowfd'. It is largely identical to the same function on other operating systems such as Solaris, DFly, NetBSD, and OpenBSD. One difference from other *BSD is that this closefrom() does not fail with any errors. In practice, while the manpages for NetBSD and OpenBSD claim that they return EINTR, they ignore internal errors from close() and never return EINTR. DFly does return EINTR, but for the common use case (closing fd's prior to execve()), the caller really wants all fd's closed and returning EINTR just forces callers to call closefrom() in a loop until it stops failing. Note that this implementation of closefrom(2) does not make any effort to resolve userland races with open(2) in other threads. As such, it is not multithread safe. Submitted by: rwatson (initial version) Reviewed by: rwatson MFC after: 2 weeks --- include/unistd.h | 1 + lib/libc/sys/Makefile.inc | 2 +- lib/libc/sys/Symbol.map | 3 + lib/libc/sys/close.2 | 1 + lib/libc/sys/closefrom.2 | 53 ++++ sys/compat/freebsd32/syscalls.master | 1 + sys/kern/kern_descrip.c | 36 +++ sys/kern/syscalls.master | 1 + tools/regression/file/closefrom/Makefile | 9 + tools/regression/file/closefrom/closefrom.c | 274 ++++++++++++++++++++ tools/regression/file/closefrom/closefrom.t | 10 + 11 files changed, 390 insertions(+), 1 deletion(-) create mode 100644 lib/libc/sys/closefrom.2 create mode 100644 tools/regression/file/closefrom/Makefile create mode 100644 tools/regression/file/closefrom/closefrom.c create mode 100644 tools/regression/file/closefrom/closefrom.t diff --git a/include/unistd.h b/include/unistd.h index 4b567b830752..aa027c21ae72 100644 --- a/include/unistd.h +++ b/include/unistd.h @@ -326,6 +326,7 @@ unsigned int alarm(unsigned int); int chdir(const char *); int chown(const char *, uid_t, gid_t); int close(int); +void closefrom(int); int dup(int); int dup2(int, int); int execl(const char *, const char *, ...); diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc index a238efced5d2..7e65aa448db0 100644 --- a/lib/libc/sys/Makefile.inc +++ b/lib/libc/sys/Makefile.inc @@ -63,7 +63,7 @@ MAN+= abort2.2 accept.2 access.2 acct.2 adjtime.2 \ aio_cancel.2 aio_error.2 aio_read.2 aio_return.2 \ aio_suspend.2 aio_waitcomplete.2 aio_write.2 \ bind.2 brk.2 chdir.2 chflags.2 \ - chmod.2 chown.2 chroot.2 clock_gettime.2 close.2 \ + chmod.2 chown.2 chroot.2 clock_gettime.2 close.2 closefrom.2 \ connect.2 cpuset.2 cpuset_getaffinity.2 dup.2 execve.2 _exit.2 \ extattr_get_file.2 fcntl.2 fhopen.2 flock.2 fork.2 fsync.2 \ getdirentries.2 getdtablesize.2 \ diff --git a/lib/libc/sys/Symbol.map b/lib/libc/sys/Symbol.map index 48ef400e90fb..9e198995d88c 100644 --- a/lib/libc/sys/Symbol.map +++ b/lib/libc/sys/Symbol.map @@ -333,6 +333,7 @@ FBSD_1.0 { }; FBSD_1.1 { + closefrom; cpuset; cpuset_getid; cpuset_setid; @@ -472,6 +473,8 @@ FBSDprivate_1.0 { __sys_clock_settime; _close; __sys_close; + _closefrom; + __sys_closefrom; _connect; __sys_connect; _cpuset; diff --git a/lib/libc/sys/close.2 b/lib/libc/sys/close.2 index aef03796222e..524322b1517b 100644 --- a/lib/libc/sys/close.2 +++ b/lib/libc/sys/close.2 @@ -120,6 +120,7 @@ before all pending data was delivered. .El .Sh SEE ALSO .Xr accept 2 , +.Xr closefrom 2 , .Xr execve 2 , .Xr fcntl 2 , .Xr flock 2 , diff --git a/lib/libc/sys/closefrom.2 b/lib/libc/sys/closefrom.2 new file mode 100644 index 000000000000..ffaa0012bae9 --- /dev/null +++ b/lib/libc/sys/closefrom.2 @@ -0,0 +1,53 @@ +.\" Copyright (c) 2009 Advanced Computing Technologies LLC +.\" Written by: John H. Baldwin +.\" All rights reserved. +.\" +.\" 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 AUTHOR 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 AUTHOR 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. +.\" +.\" $FreeBSD$ +.\" +.Dd June 12, 2009 +.Dt CLOSEFROM 2 +.Os +.Sh NAME +.Nm closefrom +.Nd delete open file descriptors +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In unistd.h +.Ft void +.Fn closefrom "int lowfd" +.Sh DESCRIPTION +The +.Fn closefrom +system call deletes all open file descriptors greater than or equal to +.Fa lowfd +from the per-process object reference table. +Any errors encountered while closing file descriptors are ignored. +.Sh SEE ALSO +.Xr close 2 +.Sh HISTORY +The +.Fn closefrom +function first appeared in +.Fx 8.0 . diff --git a/sys/compat/freebsd32/syscalls.master b/sys/compat/freebsd32/syscalls.master index 7da270b26447..f2a170007bce 100644 --- a/sys/compat/freebsd32/syscalls.master +++ b/sys/compat/freebsd32/syscalls.master @@ -889,3 +889,4 @@ 507 AUE_NULL STD { int freebsd32_jail_set(struct iovec32 *iovp, \ unsigned int iovcnt, int flags); } 508 AUE_NULL NOPROTO { int jail_remove(int jid); } +509 AUE_CLOSEFROM NOPROTO { int closefrom(int lowfd); } diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c index 122182553030..30bb84ac53d1 100644 --- a/sys/kern/kern_descrip.c +++ b/sys/kern/kern_descrip.c @@ -1128,6 +1128,42 @@ kern_close(td, fd) return (error); } +/* + * Close open file descriptors. + */ +#ifndef _SYS_SYSPROTO_H_ +struct closefrom_args { + int lowfd; +}; +#endif +/* ARGSUSED */ +int +closefrom(struct thread *td, struct closefrom_args *uap) +{ + struct filedesc *fdp; + int fd; + + fdp = td->td_proc->p_fd; + AUDIT_ARG(fd, uap->lowfd); + + /* + * Treat negative starting file descriptor values identical to + * closefrom(0) which closes all files. + */ + if (uap->lowfd < 0) + uap->lowfd = 0; + FILEDESC_SLOCK(fdp); + for (fd = uap->lowfd; fd < fdp->fd_nfiles; fd++) { + if (fdp->fd_ofiles[fd] != NULL) { + FILEDESC_SUNLOCK(fdp); + (void)kern_close(td, fd); + FILEDESC_SLOCK(fdp); + } + } + FILEDESC_SUNLOCK(fdp); + return (0); +} + #if defined(COMPAT_43) /* * Return status information about a file descriptor. diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master index ab5981e9b9a4..466d4e3a5f13 100644 --- a/sys/kern/syscalls.master +++ b/sys/kern/syscalls.master @@ -902,5 +902,6 @@ 507 AUE_NULL STD { int jail_set(struct iovec *iovp, \ unsigned int iovcnt, int flags); } 508 AUE_NULL STD { int jail_remove(int jid); } +509 AUE_CLOSEFROM STD { int closefrom(int lowfd); } ; Please copy any additions and changes to the following compatability tables: ; sys/compat/freebsd32/syscalls.master diff --git a/tools/regression/file/closefrom/Makefile b/tools/regression/file/closefrom/Makefile new file mode 100644 index 000000000000..7ff2df81ee76 --- /dev/null +++ b/tools/regression/file/closefrom/Makefile @@ -0,0 +1,9 @@ +# $FreeBSD$ + +PROG= closefrom +MAN= +WARNS?= 6 + +LDADD= -lutil + +.include diff --git a/tools/regression/file/closefrom/closefrom.c b/tools/regression/file/closefrom/closefrom.c new file mode 100644 index 000000000000..e119f20af48c --- /dev/null +++ b/tools/regression/file/closefrom/closefrom.c @@ -0,0 +1,274 @@ +/*- + * Copyright (c) 2009 Advanced Computing Technologies LLC + * Written by: John H. Baldwin + * All rights reserved. + * + * 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 AUTHOR 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 AUTHOR 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. + */ + +#include +__FBSDID("$FreeBSD$"); + +/* + * Regression tests for the closefrom(2) system call. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +struct shared_info { + int failed; + char tag[64]; + char message[0]; +}; + +static int test = 1; + +static void +ok(const char *descr) +{ + + printf("ok %d - %s\n", test, descr); + test++; +} + +static void +fail(const char *descr, const char *fmt, ...) +{ + va_list ap; + + printf("not ok %d - %s", test, descr); + test++; + if (fmt) { + va_start(ap, fmt); + printf(" # "); + vprintf(fmt, ap); + va_end(ap); + } + printf("\n"); + exit(1); +} + +#define fail_err(descr) fail((descr), "%s", strerror(errno)) + +static void +cok(struct shared_info *info, const char *descr) +{ + + info->failed = 0; + strlcpy(info->tag, descr, sizeof(info->tag)); + exit(0); +} + +static void +cfail(struct shared_info *info, const char *descr, const char *fmt, ...) +{ + va_list ap; + + info->failed = 1; + strlcpy(info->tag, descr, sizeof(info->tag)); + if (fmt) { + va_start(ap, fmt); + vsprintf(info->message, fmt, ap); + va_end(ap); + } + exit(0); +} + +#define cfail_err(info, descr) cfail((info), (descr), "%s", strerror(errno)) + +/* + * Use kinfo_getfile() to fetch the list of file descriptors and figure out + * the highest open file descriptor. + */ +static int +highest_fd(void) +{ + struct kinfo_file *kif; + int cnt, i, highest; + + kif = kinfo_getfile(getpid(), &cnt); + if (kif == NULL) + fail_err("kinfo_getfile"); + highest = INT_MIN; + for (i = 0; i < cnt; i++) + if (kif[i].kf_fd > highest) + highest = kif[i].kf_fd; + free(kif); + return (highest); +} + +static int +devnull(void) +{ + int fd; + + fd = open("/dev/null", O_RDONLY); + if (fd < 0) + fail_err("open(\"/dev/null\")"); + return (fd); +} + +int +main(int __unused argc, char __unused *argv[]) +{ + struct shared_info *info; + pid_t pid; + int fd, i; + + printf("1..15\n"); + + /* We better start up with fd's 0, 1, and 2 open. */ + fd = devnull(); + if (fd != 3) + fail("open", "bad descriptor %d", fd); + ok("open"); + + /* Make sure highest_fd() works. */ + fd = highest_fd(); + if (fd != 3) + fail("highest_fd", "bad descriptor %d", fd); + ok("highest_fd"); + + /* Try to use closefrom() for just closing fd 3. */ + closefrom(3); + fd = highest_fd(); + if (fd != 2) + fail("closefrom", "highest fd %d", fd); + ok("closefrom"); + + /* Eat up 16 descriptors. */ + for (i = 0; i < 16; i++) + (void)devnull(); + fd = highest_fd(); + if (fd != 18) + fail("open 16", "highest fd %d", fd); + ok("open 16"); + + /* Close half of them. */ + closefrom(11); + fd = highest_fd(); + if (fd != 10) + fail("closefrom", "highest fd %d", fd); + ok("closefrom"); + + /* Explicitly close descriptors 6 and 8 to create holes. */ + if (close(6) < 0 || close(8) < 0) + fail_err("close2 "); + ok("close 2"); + + /* Verify that close on 6 and 8 fails with EBADF. */ + if (close(6) == 0) + fail("close(6)", "did not fail"); + if (errno != EBADF) + fail_err("close(6)"); + ok("close(6)"); + if (close(8) == 0) + fail("close(8)", "did not fail"); + if (errno != EBADF) + fail_err("close(8)"); + ok("close(8)"); + + /* Close from 4 on. */ + closefrom(4); + fd = highest_fd(); + if (fd != 3) + fail("closefrom", "highest fd %d", fd); + ok("closefrom"); + + /* Allocate a small SHM region for IPC with our child. */ + info = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE, MAP_ANON | + MAP_SHARED, -1, 0); + if (info == MAP_FAILED) + fail_err("mmap"); + ok("mmap"); + + /* Fork a child process to test closefrom(0). */ + pid = fork(); + if (pid < 0) + fail_err("fork"); + if (pid == 0) { + /* Child. */ + closefrom(0); + fd = highest_fd(); + if (fd >= 0) + cfail(info, "closefrom(0)", "highest fd %d", fd); + cok(info, "closefrom(0)"); + } + if (wait(NULL) < 0) + fail_err("wait"); + if (info->failed) + fail(info->tag, "%s", info->message); + ok(info->tag); + + /* Fork a child process to test closefrom(-1). */ + pid = fork(); + if (pid < 0) + fail_err("fork"); + if (pid == 0) { + /* Child. */ + closefrom(-1); + fd = highest_fd(); + if (fd >= 0) + cfail(info, "closefrom(-1)", "highest fd %d", fd); + cok(info, "closefrom(-1)"); + } + if (wait(NULL) < 0) + fail_err("wait"); + if (info->failed) + fail(info->tag, "%s", info->message); + ok(info->tag); + + /* Dup stdout to 6. */ + if (dup2(1, 6) < 0) + fail_err("dup2"); + fd = highest_fd(); + if (fd != 6) + fail("dup2", "highest fd %d", fd); + ok("dup2"); + + /* Do a closefrom() starting in a hole. */ + closefrom(4); + fd = highest_fd(); + if (fd != 3) + fail("closefrom", "highest fd %d", fd); + ok("closefrom"); + + /* Do a closefrom() beyond our highest open fd. */ + closefrom(32); + fd = highest_fd(); + if (fd != 3) + fail("closefrom", "highest fd %d", fd); + ok("closefrom"); + + return (0); +} diff --git a/tools/regression/file/closefrom/closefrom.t b/tools/regression/file/closefrom/closefrom.t new file mode 100644 index 000000000000..8bdfd03be81b --- /dev/null +++ b/tools/regression/file/closefrom/closefrom.t @@ -0,0 +1,10 @@ +#!/bin/sh +# $FreeBSD$ + +cd `dirname $0` + +executable=`basename $0 .t` + +make $executable 2>&1 > /dev/null + +exec ./$executable