Commit 0fa4fe85 authored Mar 19, 2018 by Chenbo Feng Committed by Daniel Borkmann Mar 20, 2018

bpf: skip unnecessary capability check



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>

parent f005afed

kernel/bpf/syscall.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1845,7 +1845,7 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
		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;

		err = check_uarg_tail_zero(uattr, sizeof(attr), size);

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