4.4-stable review patch. If anyone has any objections, please let me know.
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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 @@ -673,7 +673,7 @@ 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))