[PATCH bpf-next v2] libbpf: use SOCK_CLOEXEC when opening the netlink socket

Otherwise, there exists a small window between the opening and closing
of the socket fd where it may leak into processes launched by some other
thread.

Fixes: 949abbe88436 ("libbpf: add function to setup XDP")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
Changelog:

v1 -> v2
Tag the bpf-next tree (Toke)
Add a Fixes: tag (Toke)
---
 tools/lib/bpf/netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index 4dd73de00..d2cb28e9e 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c

@@ -40,7 +40,7 @@ static int libbpf_netlink_open(__u32 *nl_pid)
 	memset(&sa, 0, sizeof(sa));
 	sa.nl_family = AF_NETLINK;
 
-	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	sock = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
 	if (sock < 0)
 		return -errno;
 

-- 
2.30.2

Kumar Kartikeya Dwivedi [off-list ref] writes:

Otherwise, there exists a small window between the opening and closing
of the socket fd where it may leak into processes launched by some other
thread.

Fixes: 949abbe88436 ("libbpf: add function to setup XDP")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

Acked-by: Toke Høiland-Jørgensen <redacted>

Hello:

This patch was applied to bpf/bpf.git (refs/heads/master):

On Wed, 17 Mar 2021 17:28:58 +0530 you wrote:

Otherwise, there exists a small window between the opening and closing
of the socket fd where it may leak into processes launched by some other
thread.

Fixes: 949abbe88436 ("libbpf: add function to setup XDP")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

[...]

Here is the summary with links:
  - [bpf-next,v2] libbpf: use SOCK_CLOEXEC when opening the netlink socket
    https://git.kernel.org/bpf/bpf/c/58bfd95b554f

You are awesome, thank you!
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