From: Yang Jihong <yangjihong1@huawei.com>
To: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<martin.lau@linux.dev>, <song@kernel.org>, <yhs@fb.com>,
<john.fastabend@gmail.com>, <kpsingh@kernel.org>,
<sdf@google.com>, <haoluo@google.com>, <jolsa@kernel.org>,
<illusionist.neo@gmail.com>, <linux@armlinux.org.uk>,
<davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
<pabeni@redhat.com>, <mykolal@fb.com>, <shuah@kernel.org>,
<benjamin.tissoires@redhat.com>, <memxor@gmail.com>,
<asavkov@redhat.com>, <delyank@fb.com>, <bpf@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kselftest@vger.kernel.org>
Cc: <yangjihong1@huawei.com>
Subject: [PATCH bpf v2 2/5] bpf: Adjust sk size check for sk in bpf_skb_is_valid_access for CO_RE in 32-bit arch
Date: Mon, 7 Nov 2022 17:20:29 +0800 [thread overview]
Message-ID: <20221107092032.178235-3-yangjihong1@huawei.com> (raw)
In-Reply-To: <20221107092032.178235-1-yangjihong1@huawei.com>
The error code -EACCES is returned when bpf prog is tested in 32-bit arch.
This is because bpf_object__relocate modifies instruction to change memory
size to 4 bytes, as shown in the following messages:
libbpf: prog 'kfunc_call_test1': relo #2: matching candidate #0 <byte_off> [18342] struct __sk_buff.sk (0:30:0 @ offset 168)
libbpf: prog 'kfunc_call_test1': relo #2: patched insn #1 (LDX/ST/STX) off 168 -> 168
libbpf: prog 'kfunc_call_test1': relo #2: patched insn #1 (LDX/ST/STX) mem_sz 8 -> 4
As a result, the bpf_skb_is_valid_access check fails, for 32-bit arch,
adjust check sk size.
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
---
net/core/filter.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index bb0136e7a8e4..47cbad2e609f 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8269,7 +8269,13 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type
return false;
break;
case offsetof(struct __sk_buff, sk):
- if (type == BPF_WRITE || size != sizeof(__u64))
+ /* CO_RE adjusts pointer accesses from 8-byte read to
+ * 4-byte reads in 32-bit host arch, so 32-bit can only
+ * read the 32-bit pointer or the full 64-bit value,
+ * and 64-bit can read write the 64-bit pointer.
+ */
+ if (type == BPF_WRITE ||
+ (size != sizeof(struct bpf_sock *) && size != sizeof(__u64)))
return false;
info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
break;
--
2.30.GIT
next prev parent reply other threads:[~2022-11-07 9:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-07 9:20 [PATCH bpf v2 0/5] bpf: Support kernel function call in 32-bit ARM Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 1/5] bpf: Adapt 32-bit return value kfunc for 32-bit ARM when zext extension Yang Jihong
2022-11-08 23:12 ` Martin KaFai Lau
2022-11-26 9:45 ` Yang Jihong
2022-11-07 9:20 ` Yang Jihong [this message]
2022-11-07 9:20 ` [PATCH bpf v2 3/5] libbpf: Skip adjust mem size for load pointer in 32-bit arch in CO_RE Yang Jihong
2022-11-08 1:22 ` Andrii Nakryiko
2022-11-08 2:44 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 4/5] bpf: Add kernel function call support in 32-bit ARM for EABI Yang Jihong
2022-11-07 12:33 ` Russell King (Oracle)
2022-11-08 0:52 ` Yang Jihong
2022-11-07 9:20 ` [PATCH bpf v2 5/5] bpf:selftests: Add kfunc_call test for mixing 32-bit and 64-bit parameters Yang Jihong
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