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Subject[PATCH bpf v2] restore behaviour of CAP_SYS_ADMIN allowing the loading of networking bpf programs
Date
From: Maciej Żenczykowski <maze@google.com>

This is a fix for a regression introduced in 5.8-rc1 by:
commit 2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366
'bpf: Implement CAP_BPF'

Before the above commit it was possible to load network bpf programs
with just the CAP_SYS_ADMIN privilege.

The Android bpfloader happens to run in such a configuration (it has
SYS_ADMIN but not NET_ADMIN) and creates maps and loads bpf programs
for later use by Android's netd (which has NET_ADMIN but not SYS_ADMIN).

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Reported-by: John Stultz <john.stultz@linaro.org>
Fixes: 2c78ee898d8f ("bpf: Implement CAP_BPF")
Signed-off-by: Maciej Żenczykowski <maze@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 8da159936bab..7d946435587d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2121,7 +2121,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
!bpf_capable())
return -EPERM;

- if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN))
+ if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN) && !capable(CAP_SYS_ADMIN))
return -EPERM;
if (is_perfmon_prog_type(type) && !perfmon_capable())
return -EPERM;
--
2.27.0.111.gc72c7da667-goog
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