From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BFC2C16F907; Mon, 25 Mar 2024 09:53:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711360387; cv=none; b=ksAKqHhlTHEjPcbZ3x9+STBtaKRII2wDqEOeW6ge9aa6I49FKVmI5xxwYGXLvUEY+T9S5N+uXm70FVAXHl3QoyhxRvTJ5YT34RuIJnHcjD04eFgNl2SnpUIz1bHPFZVkDruFfqB6Zp0OHHnLslF+IemLTTkN/JbYDg+W5VOuaIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711360387; c=relaxed/simple; bh=BRHU7i6ymh6GyHXPngMUaIvqxRCDm24qj8ooIdk4dsI=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=SPwggIbNRoFb2j5bwDMo72izOSd/yEXcbaSCJ1BZ1PzJUW0lVM1AGQv1XhJF+LNZwmwRujIvWrEI9SCVsHSskWVnQLHZI7lVsTeIZcPt2fYeHvmTzcbjKOU1xmXpO8jxk17WP6u2M1sRilgMUoOX9nD96TQUhuMZI2IUedIJnUE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4V37XL001Pz4f3jdW; Mon, 25 Mar 2024 17:52:49 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.252]) by mail.maildlp.com (Postfix) with ESMTP id 279121A017A; Mon, 25 Mar 2024 17:52:56 +0800 (CST) Received: from k01.huawei.com (unknown [10.67.174.197]) by APP3 (Coremail) with SMTP id _Ch0CgDn9Jx1SQFmHl6fHw--.8953S2; Mon, 25 Mar 2024 17:52:54 +0800 (CST) From: Xu Kuohai To: bpf@vger.kernel.org, linux-security-module@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Florent Revest , Brendan Jackman , Paul Moore , James Morris , "Serge E . Hallyn" , Khadija Kamran , Casey Schaufler , Ondrej Mosnacek , Kees Cook , John Johansen , Lukas Bulwahn , Roberto Sassu , Shung-Hsi Yu Subject: [PATCH bpf-next v2 0/7] Add check for bpf lsm return value Date: Mon, 25 Mar 2024 17:56:46 +0800 Message-Id: <20240325095653.1720123-1-xukuohai@huaweicloud.com> X-Mailer: git-send-email 2.30.2 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_Ch0CgDn9Jx1SQFmHl6fHw--.8953S2 X-Coremail-Antispam: 1UD129KBjvJXoWxCr4kKF48tFWxCF1rAry3CFg_yoW7JFW7pr 4YqF18Gr4Iqr4UJF18CF4UJr1fJFW7A3WUXryxJr95AF15Gr1DJr18GrWjqrnxJr4Uur17 tF9Fqa1rtry8XaDanT9S1TB71UUUUUDqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkIb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28I cxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2 IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI 42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42 IY6xAIw20EY4v20xvaj40_Wr1j6rW3Jr1lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2 z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU1c4S7UUUUU== X-CM-SenderInfo: 50xn30hkdlqx5xdzvxpfor3voofrz/ From: Xu Kuohai A bpf prog returning positive number attached to file_alloc_security hook will make kernel panic. Here is a panic log: [ 441.235774] BUG: kernel NULL pointer dereference, address: 00000000000009 [ 441.236748] #PF: supervisor write access in kernel mode [ 441.237429] #PF: error_code(0x0002) - not-present page [ 441.238119] PGD 800000000b02f067 P4D 800000000b02f067 PUD b031067 PMD 0 [ 441.238990] Oops: 0002 [#1] PREEMPT SMP PTI [ 441.239546] CPU: 0 PID: 347 Comm: loader Not tainted 6.8.0-rc6-gafe0cbf23373 #22 [ 441.240496] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b4 [ 441.241933] RIP: 0010:alloc_file+0x4b/0x190 [ 441.242485] Code: 8b 04 25 c0 3c 1f 00 48 8b b0 30 0c 00 00 e8 9c fe ff ff 48 3d 00 f0 ff fb [ 441.244820] RSP: 0018:ffffc90000c67c40 EFLAGS: 00010203 [ 441.245484] RAX: ffff888006a891a0 RBX: ffffffff8223bd00 RCX: 0000000035b08000 [ 441.246391] RDX: ffff88800b95f7b0 RSI: 00000000001fc110 RDI: f089cd0b8088ffff [ 441.247294] RBP: ffffc90000c67c58 R08: 0000000000000001 R09: 0000000000000001 [ 441.248209] R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001 [ 441.249108] R13: ffffc90000c67c78 R14: ffffffff8223bd00 R15: fffffffffffffff4 [ 441.250007] FS: 00000000005f3300(0000) GS:ffff88803ec00000(0000) knlGS:0000000000000000 [ 441.251053] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 441.251788] CR2: 00000000000001a9 CR3: 000000000bdc4003 CR4: 0000000000170ef0 [ 441.252688] Call Trace: [ 441.253011] [ 441.253296] ? __die+0x24/0x70 [ 441.253702] ? page_fault_oops+0x15b/0x480 [ 441.254236] ? fixup_exception+0x26/0x330 [ 441.254750] ? exc_page_fault+0x6d/0x1c0 [ 441.255257] ? asm_exc_page_fault+0x26/0x30 [ 441.255792] ? alloc_file+0x4b/0x190 [ 441.256257] alloc_file_pseudo+0x9f/0xf0 [ 441.256760] __anon_inode_getfile+0x87/0x190 [ 441.257311] ? lock_release+0x14e/0x3f0 [ 441.257808] bpf_link_prime+0xe8/0x1d0 [ 441.258315] bpf_tracing_prog_attach+0x311/0x570 [ 441.258916] ? __pfx_bpf_lsm_file_alloc_security+0x10/0x10 [ 441.259605] __sys_bpf+0x1bb7/0x2dc0 [ 441.260070] __x64_sys_bpf+0x20/0x30 [ 441.260533] do_syscall_64+0x72/0x140 [ 441.261004] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 441.261643] RIP: 0033:0x4b0349 [ 441.262045] Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 88 [ 441.264355] RSP: 002b:00007fff74daee38 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 [ 441.265293] RAX: ffffffffffffffda RBX: 00007fff74daef30 RCX: 00000000004b0349 [ 441.266187] RDX: 0000000000000040 RSI: 00007fff74daee50 RDI: 000000000000001c [ 441.267114] RBP: 000000000000001b R08: 00000000005ef820 R09: 0000000000000000 [ 441.268018] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004 [ 441.268907] R13: 0000000000000004 R14: 00000000005ef018 R15: 00000000004004e8 The reason is that the positive number returned by bpf prog is not a valid errno, and could not be filtered out with IS_ERR which is used by the file system to check errors. As a result, the filesystem mistakenly uses this random positive number as file pointer, causing panic. To fix this issue, there are two schemes: 1. Modify the calling sites of file_alloc_security to take positive return values as zero. 2. Make the bpf verifier to ensure no unpredicted value returned by lsm bpf prog. Considering that hook file_alloc_security never returned positive number before bpf lsm was introduced, and other lsm hooks may have the same problem, scheme 2 is more reasonable. So this patch set adds lsm return value check in verifier to fix it. v2: fix bpf ci failure v1: https://lore.kernel.org/bpf/20240316122359.1073787-1-xukuohai@huaweicloud.com/ Xu Kuohai (7): bpf, lsm: Annotate lsm hook return integer with new macro LSM_RET_INT bpf, lsm: Add return value range description for lsm hook bpf, lsm: Add function to read lsm hook return value range bpf, lsm: Check bpf lsm hook return values in verifier bpf: Fix compare error in function retval_range_within selftests/bpf: Avoid load failure for token_lsm.c selftests/bpf: Add return value checks and corrections for failed progs include/linux/bpf.h | 1 + include/linux/bpf_lsm.h | 8 + include/linux/lsm_hook_defs.h | 433 +++++++++--------- include/linux/lsm_hooks.h | 6 - kernel/bpf/bpf_lsm.c | 66 ++- kernel/bpf/btf.c | 5 +- kernel/bpf/verifier.c | 59 ++- security/security.c | 1 + tools/testing/selftests/bpf/progs/err.h | 10 + .../selftests/bpf/progs/test_sig_in_xattr.c | 4 + .../bpf/progs/test_verify_pkcs7_sig.c | 8 +- tools/testing/selftests/bpf/progs/token_lsm.c | 4 +- .../bpf/progs/verifier_global_subprogs.c | 7 +- 13 files changed, 376 insertions(+), 236 deletions(-) -- 2.30.2