From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
To: Roberto Sassu <roberto.sassu@huaweicloud.com>
Cc: 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, 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, Roberto Sassu <roberto.sassu@huawei.com>,
Joanne Koong <joannelkoong@gmail.com>
Subject: Re: [PATCH v16 03/12] btf: Allow dynamic pointer parameters in kfuncs
Date: Tue, 6 Sep 2022 04:33:20 +0200 [thread overview]
Message-ID: <CAP01T76PqKVf1f-jo=U6V1tj4DdT1STa1dkfe2gSOuiCVuZjOw@mail.gmail.com> (raw)
In-Reply-To: <20220905143318.1592015-4-roberto.sassu@huaweicloud.com>
On Mon, 5 Sept 2022 at 16:34, Roberto Sassu
<roberto.sassu@huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Allow dynamic pointers (struct bpf_dynptr_kern *) to be specified as
> parameters in kfuncs. Also, ensure that dynamic pointers passed as argument
> are valid and initialized, are a pointer to the stack, and of the type
> local. More dynamic pointer types can be supported in the future.
>
> To properly detect whether a parameter is of the desired type, introduce
> the stringify_struct() macro to compare the returned structure name with
> the desired name. In addition, protect against structure renames, by
> halting the build with BUILD_BUG_ON(), so that developers have to revisit
> the code.
>
> To check if a dynamic pointer passed to the kfunc is valid and initialized,
> and if its type is local, export the existing functions
> is_dynptr_reg_valid_init() and is_dynptr_type_expected().
>
> Cc: Joanne Koong <joannelkoong@gmail.com>
> Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> include/linux/bpf_verifier.h | 5 +++++
> include/linux/btf.h | 9 +++++++++
> kernel/bpf/btf.c | 33 +++++++++++++++++++++++++++++++++
> kernel/bpf/verifier.c | 10 +++++-----
> 4 files changed, 52 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
> index 1fdddbf3546b..dd58dfccd025 100644
> --- a/include/linux/bpf_verifier.h
> +++ b/include/linux/bpf_verifier.h
> @@ -571,6 +571,11 @@ int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state
> u32 regno);
> int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
> u32 regno, u32 mem_size);
> +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
> + struct bpf_reg_state *reg);
> +bool is_dynptr_type_expected(struct bpf_verifier_env *env,
> + struct bpf_reg_state *reg,
> + enum bpf_arg_type arg_type);
>
> /* this lives here instead of in bpf.h because it needs to dereference tgt_prog */
> static inline u64 bpf_trampoline_compute_key(const struct bpf_prog *tgt_prog,
> diff --git a/include/linux/btf.h b/include/linux/btf.h
> index ad93c2d9cc1c..f546d368ac5d 100644
> --- a/include/linux/btf.h
> +++ b/include/linux/btf.h
> @@ -52,6 +52,15 @@
> #define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */
> #define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */
>
> +/*
> + * Return the name of the passed struct, if exists, or halt the build if for
> + * example the structure gets renamed. In this way, developers have to revisit
> + * the code using that structure name, and update it accordingly.
> + */
> +#define stringify_struct(x) \
> + ({ BUILD_BUG_ON(sizeof(struct x) < 0); \
> + __stringify(x); })
> +
> struct btf;
> struct btf_member;
> struct btf_type;
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index e49b3b6d48ad..4266bff5fada 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -6362,15 +6362,20 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env,
>
> if (is_kfunc) {
> bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], ®s[regno + 1]);
> + bool arg_dynptr = btf_type_is_struct(ref_t) &&
> + !strcmp(ref_tname,
> + stringify_struct(bpf_dynptr_kern));
>
> /* Permit pointer to mem, but only when argument
> * type is pointer to scalar, or struct composed
> * (recursively) of scalars.
> * When arg_mem_size is true, the pointer can be
> * void *.
> + * Also permit initialized local dynamic pointers.
> */
> if (!btf_type_is_scalar(ref_t) &&
> !__btf_type_is_scalar_struct(log, btf, ref_t, 0) &&
> + !arg_dynptr &&
> (arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
> bpf_log(log,
> "arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
> @@ -6378,6 +6383,34 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env,
> return -EINVAL;
> }
>
> + if (arg_dynptr) {
> + if (reg->type != PTR_TO_STACK) {
> + bpf_log(log, "arg#%d pointer type %s %s not to stack\n",
> + i, btf_type_str(ref_t),
> + ref_tname);
> + return -EINVAL;
> + }
> +
> + if (!is_dynptr_reg_valid_init(env, reg)) {
> + bpf_log(log,
> + "arg#%d pointer type %s %s must be valid and initialized\n",
> + i, btf_type_str(ref_t),
> + ref_tname);
> + return -EINVAL;
> + }
> +
> + if (!is_dynptr_type_expected(env, reg,
> + ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_LOCAL)) {
> + bpf_log(log,
> + "arg#%d pointer type %s %s points to unsupported dynamic pointer type\n",
> + i, btf_type_str(ref_t),
> + ref_tname);
> + return -EINVAL;
> + }
> +
> + continue;
> + }
> +
> /* Check for mem, len pair */
> if (arg_mem_size) {
> if (check_kfunc_mem_size_reg(env, ®s[regno + 1], regno + 1)) {
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 10b3c0a81d09..8f02729074c6 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -779,8 +779,8 @@ static bool is_dynptr_reg_valid_uninit(struct bpf_verifier_env *env, struct bpf_
> return true;
> }
>
> -static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
> - struct bpf_reg_state *reg)
> +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
> + struct bpf_reg_state *reg)
> {
> struct bpf_func_state *state = func(env, reg);
> int spi = get_spi(reg->off);
> @@ -799,9 +799,9 @@ static bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
> return true;
> }
>
> -static bool is_dynptr_type_expected(struct bpf_verifier_env *env,
> - struct bpf_reg_state *reg,
> - enum bpf_arg_type arg_type)
> +bool is_dynptr_type_expected(struct bpf_verifier_env *env,
> + struct bpf_reg_state *reg,
> + enum bpf_arg_type arg_type)
> {
> struct bpf_func_state *state = func(env, reg);
> enum bpf_dynptr_type dynptr_type;
> --
> 2.25.1
>
next prev parent reply other threads:[~2022-09-06 2:34 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-05 14:33 [PATCH v16 00/12] bpf: Add kfuncs for PKCS#7 signature verification Roberto Sassu
2022-09-05 14:33 ` [PATCH v16 01/12] bpf: Allow kfuncs to be used in LSM programs Roberto Sassu
2022-09-06 2:28 ` Kumar Kartikeya Dwivedi
2022-09-05 14:33 ` [PATCH v16 02/12] bpf: Move dynptr type check to is_dynptr_type_expected() Roberto Sassu
2022-09-06 2:32 ` Kumar Kartikeya Dwivedi
2022-09-05 14:33 ` [PATCH v16 03/12] btf: Allow dynamic pointer parameters in kfuncs Roberto Sassu
2022-09-06 2:33 ` Kumar Kartikeya Dwivedi [this message]
2022-09-05 14:33 ` [PATCH v16 04/12] bpf: Export bpf_dynptr_get_size() Roberto Sassu
2022-09-06 2:33 ` Kumar Kartikeya Dwivedi
2022-09-06 3:06 ` Hou Tao
2022-09-05 14:33 ` [PATCH v16 05/12] KEYS: Move KEY_LOOKUP_ to include/linux/key.h and define KEY_LOOKUP_ALL Roberto Sassu
2022-09-05 21:38 ` Jarkko Sakkinen
2022-09-06 7:08 ` Roberto Sassu
2022-09-06 10:37 ` Jarkko Sakkinen
2022-09-06 11:04 ` Roberto Sassu
2022-09-06 11:43 ` Jarkko Sakkinen
2022-09-06 12:15 ` [PATCH v17 " Roberto Sassu
2022-09-06 12:26 ` Jarkko Sakkinen
2022-09-06 12:28 ` Roberto Sassu
2022-09-05 14:33 ` [PATCH v16 06/12] bpf: Add bpf_lookup_*_key() and bpf_key_put() kfuncs Roberto Sassu
2022-09-06 2:43 ` Kumar Kartikeya Dwivedi
2022-09-06 8:00 ` Roberto Sassu
2022-09-06 18:45 ` Alexei Starovoitov
2022-09-07 6:59 ` Roberto Sassu
2022-09-05 14:33 ` [PATCH v16 07/12] bpf: Add bpf_verify_pkcs7_signature() kfunc Roberto Sassu
2022-09-06 2:57 ` Kumar Kartikeya Dwivedi
2022-09-06 8:07 ` Roberto Sassu
2022-09-07 2:28 ` Kumar Kartikeya Dwivedi
2022-09-07 12:19 ` Roberto Sassu
2022-09-07 13:55 ` Kumar Kartikeya Dwivedi
2022-09-05 14:33 ` [PATCH v16 08/12] selftests/bpf: Compile kernel with everything as built-in Roberto Sassu
2022-09-06 3:01 ` Kumar Kartikeya Dwivedi
2022-09-05 14:33 ` [PATCH v16 09/12] selftests/bpf: Add verifier tests for bpf_lookup_*_key() and bpf_key_put() Roberto Sassu
2022-09-06 3:03 ` Kumar Kartikeya Dwivedi
2022-09-05 14:33 ` [PATCH v16 10/12] selftests/bpf: Add additional tests for bpf_lookup_*_key() Roberto Sassu
2022-09-05 14:33 ` [PATCH v16 11/12] selftests/bpf: Add test for bpf_verify_pkcs7_signature() kfunc Roberto Sassu
2022-09-05 14:33 ` [PATCH v16 12/12] selftests/bpf: Add tests for dynamic pointers parameters in kfuncs Roberto Sassu
2022-09-06 3:15 ` Kumar Kartikeya Dwivedi
2022-09-06 8:30 ` Roberto Sassu
2022-09-07 2:34 ` Kumar Kartikeya Dwivedi
2022-09-07 14:59 ` [PATCH v17 " Roberto Sassu
2022-09-07 16:02 ` Kumar Kartikeya Dwivedi
2022-09-05 19:26 ` [PATCH v16 00/12] bpf: Add kfuncs for PKCS#7 signature verification Kumar Kartikeya Dwivedi
2022-09-06 7:35 ` Roberto Sassu
2022-09-07 14:49 ` Roberto Sassu
2022-09-07 14:57 ` Kumar Kartikeya Dwivedi
2022-09-07 15:09 ` Roberto Sassu
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