netdev - [PATCH bpf] bpf: exempt CAP_BPF from checks against bpf_jit

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Message-Id: <20210922111153.19843-1-lmb@cloudflare.com>
Date:   Wed, 22 Sep 2021 12:11:52 +0100
From:   Lorenz Bauer <lmb@...udflare.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     kernel-team@...udflare.com, Lorenz Bauer <lmb@...udflare.com>,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH bpf] bpf: exempt CAP_BPF from checks against bpf_jit_limit

When introducing CAP_BPF, bpf_jit_charge_modmem was not changed to
treat programs with CAP_BPF as privileged for the purpose of JIT
memory allocation. This means that a program without CAP_BPF can
block a program with CAP_BPF from loading a program.

Fix this by checking bpf_capable in bpf_jit_charge_modmem.

Fixes: 2c78ee898d8f ("bpf: Implement CAP_BPF")
Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
---
 kernel/bpf/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 6fddc13fe67f..ea8a468dbded 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -827,7 +827,7 @@ int bpf_jit_charge_modmem(u32 pages)
 {
 	if (atomic_long_add_return(pages, &bpf_jit_current) >
 	    (bpf_jit_limit >> PAGE_SHIFT)) {
-		if (!capable(CAP_SYS_ADMIN)) {
+		if (!bpf_capable()) {
 			atomic_long_sub(pages, &bpf_jit_current);
 			return -EPERM;
 		}
-- 
2.30.2