Staging
v0.8.1
v0.8.1
https://github.com/torvalds/linux
Revision de11defebf00007677fb7ee91d9b089b78786fbb authored by Ulrich Drepper on 19 November 2008, 23:36:14 UTC, committed by Linus Torvalds on 20 November 2008, 02:49:57 UTC
Introduce a new accept4() system call. The addition of this system call matches analogous changes in 2.6.27 (dup3(), evenfd2(), signalfd4(), inotify_init1(), epoll_create1(), pipe2()) which added new system calls that differed from analogous traditional system calls in adding a flags argument that can be used to access additional functionality. The accept4() system call is exactly the same as accept(), except that it adds a flags bit-mask argument. Two flags are initially implemented. (Most of the new system calls in 2.6.27 also had both of these flags.) SOCK_CLOEXEC causes the close-on-exec (FD_CLOEXEC) flag to be enabled for the new file descriptor returned by accept4(). This is a useful security feature to avoid leaking information in a multithreaded program where one thread is doing an accept() at the same time as another thread is doing a fork() plus exec(). More details here: http://udrepper.livejournal.com/20407.html "Secure File Descriptor Handling", Ulrich Drepper). The other flag is SOCK_NONBLOCK, which causes the O_NONBLOCK flag to be enabled on the new open file description created by accept4(). (This flag is merely a convenience, saving the use of additional calls fcntl(F_GETFL) and fcntl (F_SETFL) to achieve the same result. Here's a test program. Works on x86-32. Should work on x86-64, but I (mtk) don't have a system to hand to test with. It tests accept4() with each of the four possible combinations of SOCK_CLOEXEC and SOCK_NONBLOCK set/clear in 'flags', and verifies that the appropriate flags are set on the file descriptor/open file description returned by accept4(). I tested Ulrich's patch in this thread by applying against 2.6.28-rc2, and it passes according to my test program. /* test_accept4.c Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk <mtk.manpages@gmail.com> Licensed under the GNU GPLv2 or later. */ #define _GNU_SOURCE #include <unistd.h> #include <sys/syscall.h> #include <sys/socket.h> #include <netinet/in.h> #include <stdlib.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #define PORT_NUM 33333 #define die(msg) do { perror(msg); exit(EXIT_FAILURE); } while (0) /**********************************************************************/ /* The following is what we need until glibc gets a wrapper for accept4() */ /* Flags for socket(), socketpair(), accept4() */ #ifndef SOCK_CLOEXEC #define SOCK_CLOEXEC O_CLOEXEC #endif #ifndef SOCK_NONBLOCK #define SOCK_NONBLOCK O_NONBLOCK #endif #ifdef __x86_64__ #define SYS_accept4 288 #elif __i386__ #define USE_SOCKETCALL 1 #define SYS_ACCEPT4 18 #else #error "Sorry -- don't know the syscall # on this architecture" #endif static int accept4(int fd, struct sockaddr *sockaddr, socklen_t *addrlen, int flags) { printf("Calling accept4(): flags = %x", flags); if (flags != 0) { printf(" ("); if (flags & SOCK_CLOEXEC) printf("SOCK_CLOEXEC"); if ((flags & SOCK_CLOEXEC) && (flags & SOCK_NONBLOCK)) printf(" "); if (flags & SOCK_NONBLOCK) printf("SOCK_NONBLOCK"); printf(")"); } printf("\n"); #if USE_SOCKETCALL long args[6]; args[0] = fd; args[1] = (long) sockaddr; args[2] = (long) addrlen; args[3] = flags; return syscall(SYS_socketcall, SYS_ACCEPT4, args); #else return syscall(SYS_accept4, fd, sockaddr, addrlen, flags); #endif } /**********************************************************************/ static int do_test(int lfd, struct sockaddr_in *conn_addr, int closeonexec_flag, int nonblock_flag) { int connfd, acceptfd; int fdf, flf, fdf_pass, flf_pass; struct sockaddr_in claddr; socklen_t addrlen; printf("=======================================\n"); connfd = socket(AF_INET, SOCK_STREAM, 0); if (connfd == -1) die("socket"); if (connect(connfd, (struct sockaddr *) conn_addr, sizeof(struct sockaddr_in)) == -1) die("connect"); addrlen = sizeof(struct sockaddr_in); acceptfd = accept4(lfd, (struct sockaddr *) &claddr, &addrlen, closeonexec_flag | nonblock_flag); if (acceptfd == -1) { perror("accept4()"); close(connfd); return 0; } fdf = fcntl(acceptfd, F_GETFD); if (fdf == -1) die("fcntl:F_GETFD"); fdf_pass = ((fdf & FD_CLOEXEC) != 0) == ((closeonexec_flag & SOCK_CLOEXEC) != 0); printf("Close-on-exec flag is %sset (%s); ", (fdf & FD_CLOEXEC) ? "" : "not ", fdf_pass ? "OK" : "failed"); flf = fcntl(acceptfd, F_GETFL); if (flf == -1) die("fcntl:F_GETFD"); flf_pass = ((flf & O_NONBLOCK) != 0) == ((nonblock_flag & SOCK_NONBLOCK) !=0); printf("nonblock flag is %sset (%s)\n", (flf & O_NONBLOCK) ? "" : "not ", flf_pass ? "OK" : "failed"); close(acceptfd); close(connfd); printf("Test result: %s\n", (fdf_pass && flf_pass) ? "PASS" : "FAIL"); return fdf_pass && flf_pass; } static int create_listening_socket(int port_num) { struct sockaddr_in svaddr; int lfd; int optval; memset(&svaddr, 0, sizeof(struct sockaddr_in)); svaddr.sin_family = AF_INET; svaddr.sin_addr.s_addr = htonl(INADDR_ANY); svaddr.sin_port = htons(port_num); lfd = socket(AF_INET, SOCK_STREAM, 0); if (lfd == -1) die("socket"); optval = 1; if (setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval)) == -1) die("setsockopt"); if (bind(lfd, (struct sockaddr *) &svaddr, sizeof(struct sockaddr_in)) == -1) die("bind"); if (listen(lfd, 5) == -1) die("listen"); return lfd; } int main(int argc, char *argv[]) { struct sockaddr_in conn_addr; int lfd; int port_num; int passed; passed = 1; port_num = (argc > 1) ? atoi(argv[1]) : PORT_NUM; memset(&conn_addr, 0, sizeof(struct sockaddr_in)); conn_addr.sin_family = AF_INET; conn_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); conn_addr.sin_port = htons(port_num); lfd = create_listening_socket(port_num); if (!do_test(lfd, &conn_addr, 0, 0)) passed = 0; if (!do_test(lfd, &conn_addr, SOCK_CLOEXEC, 0)) passed = 0; if (!do_test(lfd, &conn_addr, 0, SOCK_NONBLOCK)) passed = 0; if (!do_test(lfd, &conn_addr, SOCK_CLOEXEC, SOCK_NONBLOCK)) passed = 0; close(lfd); exit(passed ? EXIT_SUCCESS : EXIT_FAILURE); } [mtk.manpages@gmail.com: rewrote changelog, updated test program] Signed-off-by: Ulrich Drepper <drepper@redhat.com> Tested-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent cf7ee55
Tip revision: de11defebf00007677fb7ee91d9b089b78786fbb authored by Ulrich Drepper on 19 November 2008, 23:36:14 UTC
reintroduce accept4
reintroduce accept4
Tip revision: de11def
File | Mode | Size |
---|---|---|
9p | ||
adfs | ||
affs | ||
afs | ||
autofs | ||
autofs4 | ||
befs | ||
bfs | ||
cifs | ||
coda | ||
configfs | ||
cramfs | ||
debugfs | ||
devpts | ||
dlm | ||
ecryptfs | ||
efs | ||
exportfs | ||
ext2 | ||
ext3 | ||
ext4 | ||
fat | ||
freevxfs | ||
fuse | ||
gfs2 | ||
hfs | ||
hfsplus | ||
hostfs | ||
hpfs | ||
hppfs | ||
hugetlbfs | ||
isofs | ||
jbd | ||
jbd2 | ||
jffs2 | ||
jfs | ||
lockd | ||
minix | ||
ncpfs | ||
nfs | ||
nfs_common | ||
nfsd | ||
nls | ||
ntfs | ||
ocfs2 | ||
omfs | ||
openpromfs | ||
partitions | ||
proc | ||
qnx4 | ||
ramfs | ||
reiserfs | ||
romfs | ||
smbfs | ||
sysfs | ||
sysv | ||
ubifs | ||
udf | ||
ufs | ||
xfs | ||
Kconfig | -rw-r--r-- | 54.5 KB |
Kconfig.binfmt | -rw-r--r-- | 6.4 KB |
Makefile | -rw-r--r-- | 3.9 KB |
aio.c | -rw-r--r-- | 45.9 KB |
anon_inodes.c | -rw-r--r-- | 4.9 KB |
attr.c | -rw-r--r-- | 4.8 KB |
bad_inode.c | -rw-r--r-- | 8.0 KB |
binfmt_aout.c | -rw-r--r-- | 14.7 KB |
binfmt_elf.c | -rw-r--r-- | 53.6 KB |
binfmt_elf_fdpic.c | -rw-r--r-- | 48.0 KB |
binfmt_em86.c | -rw-r--r-- | 2.8 KB |
binfmt_flat.c | -rw-r--r-- | 26.6 KB |
binfmt_misc.c | -rw-r--r-- | 15.1 KB |
binfmt_script.c | -rw-r--r-- | 2.8 KB |
binfmt_som.c | -rw-r--r-- | 7.5 KB |
bio-integrity.c | -rw-r--r-- | 19.9 KB |
bio.c | -rw-r--r-- | 34.1 KB |
block_dev.c | -rw-r--r-- | 32.0 KB |
buffer.c | -rw-r--r-- | 87.8 KB |
char_dev.c | -rw-r--r-- | 13.2 KB |
compat.c | -rw-r--r-- | 53.1 KB |
compat_binfmt_elf.c | -rw-r--r-- | 3.4 KB |
compat_ioctl.c | -rw-r--r-- | 81.0 KB |
dcache.c | -rw-r--r-- | 60.0 KB |
dcookies.c | -rw-r--r-- | 6.3 KB |
direct-io.c | -rw-r--r-- | 34.0 KB |
dnotify.c | -rw-r--r-- | 4.6 KB |
dquot.c | -rw-r--r-- | 62.0 KB |
drop_caches.c | -rw-r--r-- | 1.6 KB |
eventfd.c | -rw-r--r-- | 5.3 KB |
eventpoll.c | -rw-r--r-- | 36.0 KB |
exec.c | -rw-r--r-- | 41.9 KB |
fcntl.c | -rw-r--r-- | 13.4 KB |
fifo.c | -rw-r--r-- | 3.2 KB |
file.c | -rw-r--r-- | 12.1 KB |
file_table.c | -rw-r--r-- | 10.0 KB |
filesystems.c | -rw-r--r-- | 6.3 KB |
fs-writeback.c | -rw-r--r-- | 22.4 KB |
generic_acl.c | -rw-r--r-- | 4.2 KB |
inode.c | -rw-r--r-- | 37.7 KB |
inotify.c | -rw-r--r-- | 25.1 KB |
inotify_user.c | -rw-r--r-- | 18.8 KB |
internal.h | -rw-r--r-- | 1.4 KB |
ioctl.c | -rw-r--r-- | 12.1 KB |
ioprio.c | -rw-r--r-- | 5.0 KB |
libfs.c | -rw-r--r-- | 20.6 KB |
locks.c | -rw-r--r-- | 57.6 KB |
mbcache.c | -rw-r--r-- | 18.3 KB |
mpage.c | -rw-r--r-- | 19.8 KB |
namei.c | -rw-r--r-- | 69.2 KB |
namespace.c | -rw-r--r-- | 58.0 KB |
nfsctl.c | -rw-r--r-- | 2.4 KB |
no-block.c | -rw-r--r-- | 663 bytes |
open.c | -rw-r--r-- | 26.3 KB |
pipe.c | -rw-r--r-- | 24.1 KB |
pnode.c | -rw-r--r-- | 8.9 KB |
pnode.h | -rw-r--r-- | 1.1 KB |
posix_acl.c | -rw-r--r-- | 8.5 KB |
quota.c | -rw-r--r-- | 12.2 KB |
quota_v1.c | -rw-r--r-- | 5.9 KB |
quota_v2.c | -rw-r--r-- | 20.2 KB |
read_write.c | -rw-r--r-- | 18.0 KB |
read_write.h | -rw-r--r-- | 542 bytes |
readdir.c | -rw-r--r-- | 6.9 KB |
select.c | -rw-r--r-- | 21.4 KB |
seq_file.c | -rw-r--r-- | 13.0 KB |
signalfd.c | -rw-r--r-- | 7.1 KB |
splice.c | -rw-r--r-- | 38.9 KB |
stack.c | -rw-r--r-- | 1.1 KB |
stat.c | -rw-r--r-- | 10.6 KB |
super.c | -rw-r--r-- | 22.9 KB |
sync.c | -rw-r--r-- | 7.1 KB |
timerfd.c | -rw-r--r-- | 6.8 KB |
utimes.c | -rw-r--r-- | 5.6 KB |
xattr.c | -rw-r--r-- | 15.0 KB |
xattr_acl.c | -rw-r--r-- | 2.3 KB |
Computing file changes ...