From a21b0b354d4ac39be691f51c53562e2c24443d9e Mon Sep 17 00:00:00 2001 From: Yann Droneaud Date: Sun, 5 Jan 2014 21:36:33 +0100 Subject: perf: Introduce a flag to enable close-on-exec in perf_event_open() Unlike recent modern userspace API such as: epoll_create1 (EPOLL_CLOEXEC), eventfd (EFD_CLOEXEC), fanotify_init (FAN_CLOEXEC), inotify_init1 (IN_CLOEXEC), signalfd (SFD_CLOEXEC), timerfd_create (TFD_CLOEXEC), or the venerable general purpose open (O_CLOEXEC), perf_event_open() syscall lack a flag to atomically set FD_CLOEXEC (eg. close-on-exec) flag on file descriptor it returns to userspace. The present patch adds a PERF_FLAG_FD_CLOEXEC flag to allow perf_event_open() syscall to atomically set close-on-exec. Having this flag will enable userspace to remove the file descriptor from the list of file descriptors being inherited across exec, without the need to call fcntl(fd, F_SETFD, FD_CLOEXEC) and the associated race condition between the current thread and another thread calling fork(2) then execve(2). Links: - Secure File Descriptor Handling (Ulrich Drepper, 2008) http://udrepper.livejournal.com/20407.html - Excuse me son, but your code is leaking !!! (Dan Walsh, March 2012) http://danwalsh.livejournal.com/53603.html - Notes in DMA buffer sharing: leak and security hole http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/dma-buf-sharing.txt?id=v3.13-rc3#n428 Signed-off-by: Yann Droneaud Cc: Arnaldo Carvalho de Melo Cc: Al Viro Cc: Andrew Morton Cc: Paul Mackerras Cc: Linus Torvalds Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/8c03f54e1598b1727c19706f3af03f98685d9fe6.1388952061.git.ydroneaud@opteya.com Signed-off-by: Ingo Molnar --- include/uapi/linux/perf_event.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index e1802d6153ae..ca018b4085c6 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -724,6 +724,7 @@ enum perf_callchain_context { #define PERF_FLAG_FD_NO_GROUP (1U << 0) #define PERF_FLAG_FD_OUTPUT (1U << 1) #define PERF_FLAG_PID_CGROUP (1U << 2) /* pid=cgroup id, per-cpu mode only */ +#define PERF_FLAG_FD_CLOEXEC (1U << 3) /* O_CLOEXEC */ union perf_mem_data_src { __u64 val; -- cgit v1.2.3