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bpf: Allow multiple modifiers in reg_type_str() prefix

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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>
Link: https://lore.kernel.org/r/20221120051004.3605026-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
David Vernet 2022-11-19 23:10:01 -06:00 committed by Alexei Starovoitov
parent ee748cd95e
commit ef66c5475d
2 changed files with 9 additions and 12 deletions
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2
include/linux/bpf_verifier.h
View File

@ -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

19
kernel/bpf/verifier.c
View File

@ -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);