This is a note to let you know that I've just added the patch titled
bpf: skip unnecessary capability check
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: bpf-skip-unnecessary-capability-check.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 0fa4fe85f4724fff89b09741c437cbee9cf8b008 Mon Sep 17 00:00:00 2001
From: Chenbo Feng fengc@google.com Date: Mon, 19 Mar 2018 17:57:27 -0700 Subject: bpf: skip unnecessary capability check
From: Chenbo Feng fengc@google.com
commit 0fa4fe85f4724fff89b09741c437cbee9cf8b008 upstream.
The current check statement in BPF syscall will do a capability check for CAP_SYS_ADMIN before checking sysctl_unprivileged_bpf_disabled. This code path will trigger unnecessary security hooks on capability checking and cause false alarms on unprivileged process trying to get CAP_SYS_ADMIN access. This can be resolved by simply switch the order of the statement and CAP_SYS_ADMIN is not required anyway if unprivileged bpf syscall is allowed.
Signed-off-by: Chenbo Feng fengc@google.com Acked-by: Lorenzo Colitti lorenzo@google.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/bpf/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -801,7 +801,7 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf union bpf_attr attr = {}; int err;
- if (!capable(CAP_SYS_ADMIN) && sysctl_unprivileged_bpf_disabled) + if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) return -EPERM;
if (!access_ok(VERIFY_READ, uattr, 1))
Patches currently in stable-queue which might be from fengc@google.com are
queue-4.9/kbuild-disable-clang-s-default-use-of-fmerge-all-constants.patch queue-4.9/bpf-skip-unnecessary-capability-check.patch