diff mbox series

[bpf-next,2/2] libbpf: ensure FD >= 3 during bpf_map__reuse_fd()

Message ID 20230525221311.2136408-2-andrii@kernel.org (mailing list archive)
State Accepted
Commit 4aadd2920b81b3d7e5c8ac63c7d5d673f3c8aaeb
Delegated to: BPF
Headers show
Series [bpf-next,1/2] libbpf: ensure libbpf always opens files with O_CLOEXEC | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 8 this patch: 8
netdev/cc_maintainers warning 8 maintainers not CCed: yhs@fb.com kpsingh@kernel.org martin.lau@linux.dev john.fastabend@gmail.com song@kernel.org sdf@google.com jolsa@kernel.org haoluo@google.com
netdev/build_clang success Errors and warnings before: 8 this patch: 8
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 8 this patch: 8
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 24 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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Commit Message

Andrii Nakryiko May 25, 2023, 10:13 p.m. UTC 
Improve bpf_map__reuse_fd() logic and ensure that dup'ed map FD is
"good" (>= 3) and has O_CLOEXEC flags. Use fcntl(F_DUPFD_CLOEXEC) for
that, similarly to ensure_good_fd() helper we already use in low-level
APIs that work with bpf() syscall.

Suggested-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 60ef4c5e3bee..47632606b06d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4414,18 +4414,17 @@  int bpf_map__reuse_fd(struct bpf_map *map, int fd)
 	if (!new_name)
 		return libbpf_err(-errno);
 
-	new_fd = open("/", O_RDONLY | O_CLOEXEC);
+	/*
+	 * Like dup(), but make sure new FD is >= 3 and has O_CLOEXEC set.
+	 * This is similar to what we do in ensure_good_fd(), but without
+	 * closing original FD.
+	 */
+	new_fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
 	if (new_fd < 0) {
 		err = -errno;
 		goto err_free_new_name;
 	}
 
-	new_fd = dup3(fd, new_fd, O_CLOEXEC);
-	if (new_fd < 0) {
-		err = -errno;
-		goto err_close_new_fd;
-	}
-
 	err = zclose(map->fd);
 	if (err) {
 		err = -errno;