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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>,
	<delyank@fb.com>, <asavkov@redhat.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 RESEND 2/4] bpf: Remove size check for sk in bpf_skb_is_valid_access for 32-bit architecture
Date: Thu, 3 Nov 2022 17:21:16 +0800	[thread overview]
Message-ID: <20221103092118.248600-3-yangjihong1@huawei.com> (raw)
In-Reply-To: <20221103092118.248600-1-yangjihong1@huawei.com>

The error code -EACCES is returned when bpf prog is tested in 32-bit environment,
This is because bpf_object__relocate modifies the 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 architecture,
unnecessary checks need to be deleted.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
---
 net/core/filter.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index bb0136e7a8e4..eab7ce89740c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8269,8 +8269,6 @@ 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))
-			return false;
 		info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
 		break;
 	case offsetof(struct __sk_buff, tstamp_type):
-- 
2.30.GIT


WARNING: multiple messages have this Message-ID (diff)
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>,
	<delyank@fb.com>, <asavkov@redhat.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 RESEND 2/4] bpf: Remove size check for sk in bpf_skb_is_valid_access for 32-bit architecture
Date: Thu, 3 Nov 2022 17:21:16 +0800	[thread overview]
Message-ID: <20221103092118.248600-3-yangjihong1@huawei.com> (raw)
In-Reply-To: <20221103092118.248600-1-yangjihong1@huawei.com>

The error code -EACCES is returned when bpf prog is tested in 32-bit environment,
This is because bpf_object__relocate modifies the 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 architecture,
unnecessary checks need to be deleted.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
---
 net/core/filter.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index bb0136e7a8e4..eab7ce89740c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8269,8 +8269,6 @@ 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))
-			return false;
 		info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
 		break;
 	case offsetof(struct __sk_buff, tstamp_type):
-- 
2.30.GIT


_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-11-03  9:26 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-03  9:21 [PATCH bpf RESEND 0/4] bpf: Support kernel function call in 32-bit ARM Yang Jihong
2022-11-03  9:21 ` Yang Jihong
2022-11-03  9:21 ` [PATCH bpf RESEND 1/4] bpf: Adapt 32-bit return value kfunc for 32-bit ARM when zext extension Yang Jihong
2022-11-03  9:21   ` Yang Jihong
2022-11-03  9:21 ` Yang Jihong [this message]
2022-11-03  9:21   ` [PATCH bpf RESEND 2/4] bpf: Remove size check for sk in bpf_skb_is_valid_access for 32-bit architecture Yang Jihong
2022-11-03 11:23   ` Russell King (Oracle)
2022-11-03 11:23     ` Russell King (Oracle)
2022-11-03 18:15     ` Alexei Starovoitov
2022-11-03 18:15       ` Alexei Starovoitov
2022-11-04 22:43       ` Andrii Nakryiko
2022-11-04 22:43         ` Andrii Nakryiko
2022-11-04 23:37         ` Alexei Starovoitov
2022-11-04 23:37           ` Alexei Starovoitov
2022-11-07  9:22           ` Yang Jihong
2022-11-07  9:22             ` Yang Jihong
2022-11-07  9:12     ` Yang Jihong
2022-11-07  9:12       ` Yang Jihong
2022-11-03  9:21 ` [PATCH bpf RESEND 3/4] bpf: Add kernel function call support in 32-bit ARM Yang Jihong
2022-11-03  9:21   ` Yang Jihong
2022-11-03 11:35   ` Russell King (Oracle)
2022-11-03 11:35     ` Russell King (Oracle)
2022-11-07  9:10     ` Yang Jihong
2022-11-07  9:10       ` Yang Jihong
2022-11-03  9:21 ` [PATCH bpf RESEND 4/4] bpf:selftests: Add kfunc_call test for mixing 32-bit and 64-bit parameters Yang Jihong
2022-11-03  9:21   ` Yang Jihong

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