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From: David Vernet <void@manifault.com>
To: ast@kernel.org
Cc: andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev,
	yhs@fb.com, song@kernel.org, sdf@google.com,
	john.fastabend@gmail.com, haoluo@google.com, jolsa@kernel.org,
	kpsingh@kernel.org, memxor@gmail.com, tj@kernel.org,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com
Subject: [PATCH bpf-next v9 1/4] bpf: Allow multiple modifiers in reg_type_str() prefix
Date: Sat, 19 Nov 2022 23:10:01 -0600	[thread overview]
Message-ID: <20221120051004.3605026-2-void@manifault.com> (raw)
In-Reply-To: <20221120051004.3605026-1-void@manifault.com>

reg_type_str() in the verifier currently only allows a single register
type modifier to be present in the 'prefix' string which is eventually
stored in the env type_str_buf. This currently works fine because there
are no overlapping type modifiers, but once PTR_TRUSTED is added, that
will no longer be the case. This patch updates reg_type_str() to support
having multiple modifiers in the prefix string, and updates the size of
type_str_buf to be 128 bytes.

Signed-off-by: David Vernet <void@manifault.com>
---
 include/linux/bpf_verifier.h |  2 +-
 kernel/bpf/verifier.c        | 19 ++++++++-----------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 23f30c685f28..608dde740fef 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -19,7 +19,7 @@
  */
 #define BPF_MAX_VAR_SIZ	(1 << 29)
 /* size of type_str_buf in bpf_verifier. */
-#define TYPE_STR_BUF_LEN 64
+#define TYPE_STR_BUF_LEN 128
 
 /* Liveness marks, used for registers and spilled-regs (in stack slots).
  * Read marks propagate upwards until they find a write mark; they record that
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 195d24316750..67a6f11d953c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -557,7 +557,7 @@ static bool is_cmpxchg_insn(const struct bpf_insn *insn)
 static const char *reg_type_str(struct bpf_verifier_env *env,
 				enum bpf_reg_type type)
 {
-	char postfix[16] = {0}, prefix[32] = {0};
+	char postfix[16] = {0}, prefix[64] = {0};
 	static const char * const str[] = {
 		[NOT_INIT]		= "?",
 		[SCALAR_VALUE]		= "scalar",
@@ -589,16 +589,13 @@ static const char *reg_type_str(struct bpf_verifier_env *env,
 			strncpy(postfix, "_or_null", 16);
 	}
 
-	if (type & MEM_RDONLY)
-		strncpy(prefix, "rdonly_", 32);
-	if (type & MEM_RINGBUF)
-		strncpy(prefix, "ringbuf_", 32);
-	if (type & MEM_USER)
-		strncpy(prefix, "user_", 32);
-	if (type & MEM_PERCPU)
-		strncpy(prefix, "percpu_", 32);
-	if (type & PTR_UNTRUSTED)
-		strncpy(prefix, "untrusted_", 32);
+	snprintf(prefix, sizeof(prefix), "%s%s%s%s%s",
+		 type & MEM_RDONLY ? "rdonly_" : "",
+		 type & MEM_RINGBUF ? "ringbuf_" : "",
+		 type & MEM_USER ? "user_" : "",
+		 type & MEM_PERCPU ? "percpu_" : "",
+		 type & PTR_UNTRUSTED ? "untrusted_" : ""
+	);
 
 	snprintf(env->type_str_buf, TYPE_STR_BUF_LEN, "%s%s%s",
 		 prefix, str[base_type(type)], postfix);
-- 
2.38.1


  reply	other threads:[~2022-11-20  5:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-20  5:10 [PATCH bpf-next v9 0/4] Support storing struct task_struct objects as kptrs David Vernet
2022-11-20  5:10 ` David Vernet [this message]
2022-11-20  5:10 ` [PATCH bpf-next v9 2/4] bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs David Vernet
2022-11-20 17:28   ` Alexei Starovoitov
2022-11-20 17:39     ` David Vernet
2022-11-20 19:45   ` Kumar Kartikeya Dwivedi
2022-11-21 15:31     ` David Vernet
2022-11-21 16:06       ` Kumar Kartikeya Dwivedi
2022-11-20  5:10 ` [PATCH bpf-next v9 3/4] bpf: Add kfuncs for storing struct task_struct * as a kptr David Vernet
2022-12-05 10:11   ` Matus Jokay
2022-12-05 15:02     ` David Vernet
2022-11-20  5:10 ` [PATCH bpf-next v9 4/4] bpf/selftests: Add selftests for new task kfuncs David Vernet
2022-11-20 17:30 ` [PATCH bpf-next v9 0/4] Support storing struct task_struct objects as kptrs patchwork-bot+netdevbpf

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