From: Chenbo Feng <chenbofeng.kernel@gmail•com>
To: netdev@vger•kernel.org, ast@kernel•org
Cc: Jeffrey Vander Stoep <jeffv@google•com>,
lorenzo@google•com, Daniel Borkmann <daniel@iogearbox•net>,
Chenbo Feng <fengc@google•com>
Subject: [PATCH bpf-next] bpf: skip unnecessary capability check
Date: Mon, 19 Mar 2018 17:57:27 -0700 [thread overview]
Message-ID: <20180320005727.197544-1-chenbofeng.kernel@gmail.com> (raw)
From: Chenbo Feng <fengc@google•com>
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>
---
kernel/bpf/syscall.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e24aa3241387..43f95d190eea 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -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);
--
2.16.2.804.g6dcf76e118-goog
next reply other threads:[~2018-03-20 0:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 0:57 Chenbo Feng [this message]
2018-03-20 11:37 ` [PATCH bpf-next] bpf: skip unnecessary capability check Lorenzo Colitti
2018-03-20 22:55 ` Daniel Borkmann
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