linux-kernel - [PATCH] seccomp: allow BPF

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Message-Id: <20200316163646.2465-1-a.s.protopopov@gmail.com>
Date:   Mon, 16 Mar 2020 16:36:46 +0000
From:   Anton Protopopov <a.s.protopopov@...il.com>
To:     Kees Cook <keescook@...omium.org>,
        Andy Lutomirski <luto@...capital.net>,
        Will Drewry <wad@...omium.org>, linux-kernel@...r.kernel.org
Cc:     Anton Protopopov <a.s.protopopov@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>, bpf@...r.kernel.org
Subject: [PATCH] seccomp: allow BPF_MOD ALU instructions

The BPF_MOD ALU instructions could be utilized by seccomp classic BPF filters,
but were missing from the explicit list of allowed calls since its introduction
in the original e2cfabdfd075 ("seccomp: add system call filtering using BPF")
commit.  Add support for these instructions by adding them to the allowed list
in the seccomp_check_filter function.

Signed-off-by: Anton Protopopov <a.s.protopopov@...il.com>
---
 kernel/seccomp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index b6ea3dcb57bf..cae7561b44d4 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -206,6 +206,8 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
 		case BPF_ALU | BPF_MUL | BPF_X:
 		case BPF_ALU | BPF_DIV | BPF_K:
 		case BPF_ALU | BPF_DIV | BPF_X:
+		case BPF_ALU | BPF_MOD | BPF_K:
+		case BPF_ALU | BPF_MOD | BPF_X:
 		case BPF_ALU | BPF_AND | BPF_K:
 		case BPF_ALU | BPF_AND | BPF_X:
 		case BPF_ALU | BPF_OR | BPF_K:
-- 
2.19.1