From: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Date: Mon, 7 Mar 2022 13:29:18 +0800
Subject: bpf: Determine buf_info inside check_buffer_access()
Patch-mainline: v5.18-rc1
Git-commit: 44e9a741cad824f45112b79c21d88c201d5aec13
References: jsc#PED-1377
Instead of determining buf_info string in the caller of check_buffer_access(),
we can determine whether the register type is read-only through
type_is_rdonly_mem() helper inside check_buffer_access() and construct
buf_info, making the code slightly cleaner.
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/YiWYLnAkEZXBP/gH@syu-laptop
---
kernel/bpf/verifier.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4062,9 +4062,9 @@ static int check_buffer_access(struct bp
const struct bpf_reg_state *reg,
int regno, int off, int size,
bool zero_size_allowed,
- const char *buf_info,
u32 *max_access)
{
+ const char *buf_info = type_is_rdonly_mem(reg->type) ? "rdonly" : "rdwr";
int err;
err = __check_buffer_access(env, buf_info, reg, regno, off, size);
@@ -4576,7 +4576,6 @@ static int check_mem_access(struct bpf_v
value_regno);
} else if (base_type(reg->type) == PTR_TO_BUF) {
bool rdonly_mem = type_is_rdonly_mem(reg->type);
- const char *buf_info;
u32 *max_access;
if (rdonly_mem) {
@@ -4585,15 +4584,13 @@ static int check_mem_access(struct bpf_v
regno, reg_type_str(env, reg->type));
return -EACCES;
}
- buf_info = "rdonly";
max_access = &env->prog->aux->max_rdonly_access;
} else {
- buf_info = "rdwr";
max_access = &env->prog->aux->max_rdwr_access;
}
err = check_buffer_access(env, reg, regno, off, size, false,
- buf_info, max_access);
+ max_access);
if (!err && value_regno >= 0 && (rdonly_mem || t == BPF_READ))
mark_reg_unknown(env, regs, value_regno);
@@ -4856,7 +4853,6 @@ static int check_helper_mem_access(struc
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
- const char *buf_info;
u32 *max_access;
switch (base_type(reg->type)) {
@@ -4883,15 +4879,13 @@ static int check_helper_mem_access(struc
if (meta && meta->raw_mode)
return -EACCES;
- buf_info = "rdonly";
max_access = &env->prog->aux->max_rdonly_access;
} else {
- buf_info = "rdwr";
max_access = &env->prog->aux->max_rdwr_access;
}
return check_buffer_access(env, reg, regno, reg->off,
access_size, zero_size_allowed,
- buf_info, max_access);
+ max_access);
case PTR_TO_STACK:
return check_stack_range_initialized(
env,