6.10-stable review patch. If anyone has any objections, please let me know.
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From: Andrii Nakryiko andrii@kernel.org
[ Upstream commit 531876c80004ecff7bfdbd8ba6c6b48835ef5e22 ]
Make sure to preserve and/or enforce FD_CLOEXEC flag on duped FDs. Use dup3() with O_CLOEXEC flag for that.
Without this fix libbpf effectively clears FD_CLOEXEC flag on each of BPF map/prog FD, which is definitely not the right or expected behavior.
Reported-by: Lennart Poettering lennart@poettering.net Fixes: bc308d011ab8 ("libbpf: call dup2() syscall directly") Signed-off-by: Andrii Nakryiko andrii@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org Link: https://lore.kernel.org/r/20240529223239.504241-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/lib/bpf/libbpf_internal.h | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index a0dcfb82e455d..7e7e686008c62 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -597,13 +597,9 @@ static inline int ensure_good_fd(int fd) return fd; }
-static inline int sys_dup2(int oldfd, int newfd) +static inline int sys_dup3(int oldfd, int newfd, int flags) { -#ifdef __NR_dup2 - return syscall(__NR_dup2, oldfd, newfd); -#else - return syscall(__NR_dup3, oldfd, newfd, 0); -#endif + return syscall(__NR_dup3, oldfd, newfd, flags); }
/* Point *fixed_fd* to the same file that *tmp_fd* points to. @@ -614,7 +610,7 @@ static inline int reuse_fd(int fixed_fd, int tmp_fd) { int err;
- err = sys_dup2(tmp_fd, fixed_fd); + err = sys_dup3(tmp_fd, fixed_fd, O_CLOEXEC); err = err < 0 ? -errno : 0; close(tmp_fd); /* clean up temporary FD */ return err;