Commit ef66c547 authored by David Vernet's avatar David Vernet Committed by Alexei Starovoitov
Browse files

bpf: Allow multiple modifiers in reg_type_str() prefix 



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: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221120051004.3605026-2-void@manifault.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent ee748cd9

include/linux/bpf_verifier.h

+1 −1
Original line number Diff line number Diff line
@@ -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

kernel/bpf/verifier.c

+8 −11
Original line number Diff line number Diff line
@@ -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);