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path: root/include/asm-generic/fcntl.h
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2007-07-16Introduce O_CLOEXECUlrich Drepper
The problem is as follows: in multi-threaded code (or more correctly: all code using clone() with CLONE_FILES) we have a race when exec'ing. thread #1 thread #2 fd=open() fork + exec fcntl(fd,F_SETFD,FD_CLOEXEC) In some applications this can happen frequently. Take a web browser. One thread opens a file and another thread starts, say, an external PDF viewer. The result can even be a security issue if that open file descriptor refers to a sensitive file and the external program can somehow be tricked into using that descriptor. Just adding O_CLOEXEC support to open() doesn't solve the whole set of problems. There are other ways to create file descriptors (socket, epoll_create, Unix domain socket transfer, etc). These can and should be addressed separately though. open() is such an easy case that it makes not much sense putting the fix off. The test program: #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <unistd.h> #ifndef O_CLOEXEC # define O_CLOEXEC 02000000 #endif int main (int argc, char *argv[]) { int fd; if (argc > 1) { fd = atol (argv[1]); printf ("child: fd = %d\n", fd); if (fcntl (fd, F_GETFD) == 0 || errno != EBADF) { puts ("file descriptor valid in child"); return 1; } return 0; } fd = open ("/proc/self/exe", O_RDONLY | O_CLOEXEC); printf ("in parent: new fd = %d\n", fd); char buf[20]; snprintf (buf, sizeof (buf), "%d", fd); execl ("/proc/self/exe", argv[0], buf, NULL); puts ("execl failed"); return 1; } [kyle@parisc-linux.org: parisc fix] Signed-off-by: Ulrich Drepper <drepper@redhat.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Chris Zankel <chris@zankel.net> Signed-off-by: Kyle McMartin <kyle@parisc-linux.org> Acked-by: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-04-26Don't include linux/config.h from anywhere else in include/David Woodhouse
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2005-09-07[PATCH] Clean up struct flock64 definitionsStephen Rothwell
This patch gathers all the struct flock64 definitions (and the operations), puts them under !CONFIG_64BIT and cleans up the arch files. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] Clean up struct flock definitionsStephen Rothwell
This patch just gathers together all the struct flock definitions except xtensa into asm-generic/fcntl.h. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] Clean up the fcntl operationsStephen Rothwell
This patch puts the most popular of each fcntl operation/flag into asm-generic/fcntl.h and cleans up the arch files. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] Clean up the open flagsStephen Rothwell
This patch puts the most popular of each open flag into asm-generic/fcntl.h and cleans up the arch files. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] Create asm-generic/fcntl.hStephen Rothwell
This set of patches creates asm-generic/fcntl.h and consolidates as much as possible from the asm-*/fcntl.h files into it. This patch just gathers all the identical bits of the asm-*/fcntl.h files into asm-generic/fcntl.h. Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>