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From: Roberto Sassu <roberto.sassu@huaweicloud.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, mykolal@fb.com,
	dhowells@redhat.com, jarkko@kernel.org, rostedt@goodmis.org,
	mingo@redhat.com, paul@paul-moore.com, jmorris@namei.org,
	serge@hallyn.com, shuah@kernel.org
Cc: bpf@vger.kernel.org, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	deso@posteo.net, memxor@gmail.com,
	Roberto Sassu <roberto.sassu@huawei.com>,
	stable@vger.kernel.org, Joanne Koong <joannelkoong@gmail.com>
Subject: [PATCH v18 02/13] btf: Export bpf_dynptr definition
Date: Tue, 20 Sep 2022 09:59:40 +0200	[thread overview]
Message-ID: <20220920075951.929132-3-roberto.sassu@huaweicloud.com> (raw)
In-Reply-To: <20220920075951.929132-1-roberto.sassu@huaweicloud.com>

From: Roberto Sassu <roberto.sassu@huawei.com>

eBPF dynamic pointers is a new feature recently added to upstream. It binds
together a pointer to a memory area and its size. The internal kernel
structure bpf_dynptr_kern is not accessible by eBPF programs in user space.
They instead see bpf_dynptr, which is then translated to the internal
kernel structure by the eBPF verifier.

The problem is that it is not possible to include at the same time the uapi
include linux/bpf.h and the vmlinux BTF vmlinux.h, as they both contain the
definition of some structures/enums. The compiler complains saying that the
structures/enums are redefined.

As bpf_dynptr is defined in the uapi include linux/bpf.h, this makes it
impossible to include vmlinux.h. However, in some cases, e.g. when using
kfuncs, vmlinux.h has to be included. The only option until now was to
include vmlinux.h and add the definition of bpf_dynptr directly in the eBPF
program source code from linux/bpf.h.

Solve the problem by using the same approach as for bpf_timer (which also
follows the same scheme with the _kern suffix for the internal kernel
structure).

Add the following line in one of the dynamic pointer helpers,
bpf_dynptr_from_mem():

BTF_TYPE_EMIT(struct bpf_dynptr);

Cc: stable@vger.kernel.org
Cc: Joanne Koong <joannelkoong@gmail.com>
Fixes: 97e03f521050c ("bpf: Add verifier support for dynptrs")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
---
 kernel/bpf/helpers.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 41aeaf3862ec..7ce1f583b929 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1446,6 +1446,8 @@ BPF_CALL_4(bpf_dynptr_from_mem, void *, data, u32, size, u64, flags, struct bpf_
 {
 	int err;
 
+	BTF_TYPE_EMIT(struct bpf_dynptr);
+
 	err = bpf_dynptr_check_size(size);
 	if (err)
 		goto error;
-- 
2.25.1


  parent reply	other threads:[~2022-09-20  8:01 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20  7:59 [PATCH v18 00/13] bpf: Add kfuncs for PKCS#7 signature verification Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 01/13] bpf: Allow kfuncs to be used in LSM programs Roberto Sassu
2022-09-20  7:59 ` Roberto Sassu [this message]
2022-09-21 13:43   ` [PATCH v18 02/13] btf: Export bpf_dynptr definition KP Singh
2022-09-20  7:59 ` [PATCH v18 03/13] bpf: Move dynptr type check to is_dynptr_type_expected() Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 04/13] btf: Allow dynamic pointer parameters in kfuncs Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 05/13] bpf: Export bpf_dynptr_get_size() Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 06/13] KEYS: Move KEY_LOOKUP_ to include/linux/key.h and define KEY_LOOKUP_ALL Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 07/13] bpf: Add bpf_lookup_*_key() and bpf_key_put() kfuncs Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 08/13] bpf: Add bpf_verify_pkcs7_signature() kfunc Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 09/13] selftests/bpf: Compile kernel with everything as built-in Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 10/13] selftests/bpf: Add verifier tests for bpf_lookup_*_key() and bpf_key_put() Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 11/13] selftests/bpf: Add additional tests for bpf_lookup_*_key() Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 12/13] selftests/bpf: Add test for bpf_verify_pkcs7_signature() kfunc Roberto Sassu
2022-09-20  7:59 ` [PATCH v18 13/13] selftests/bpf: Add tests for dynamic pointers parameters in kfuncs Roberto Sassu
2022-09-22  1:10 ` [PATCH v18 00/13] bpf: Add kfuncs for PKCS#7 signature verification patchwork-bot+netdevbpf
  -- strict thread matches above, loose matches on Subject: below --
2022-09-19 13:09 [PATCH v17 11/12] selftests/bpf: Add test for bpf_verify_pkcs7_signature() kfunc Roberto Sassu
2022-09-19 14:27 ` [PATCH v18 02/13] btf: Export bpf_dynptr definition Roberto Sassu
2022-09-20  5:30   ` Yonghong Song
2022-09-22  1:10   ` patchwork-bot+netdevbpf

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