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bpf: skip unnecessary capability check 

commit 0fa4fe85f4 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>
pull/10/head
Chenbo Feng 2018-03-19 17:57:27 -07:00 committed by Greg Kroah-Hartman
parent 3e1130970e
commit b4e02202a0
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/syscall.c
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@ -1455,7 +1455,7 @@ 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);