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bpf: Determine buf_info inside check_buffer_access() 

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
This commit is contained in:
Shung-Hsi Yu 2022-03-07 13:29:18 +08:00 committed by Daniel Borkmann
parent e878ae2d1d
commit 44e9a741ca
1 changed files with 3 additions and 9 deletions
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12
kernel/bpf/verifier.c
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@ -4062,9 +4062,9 @@ static int check_buffer_access(struct bpf_verifier_env *env,
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_verifier_env *env, int insn_idx, u32 regn
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_verifier_env *env, int insn_idx, u32 regn
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(struct bpf_verifier_env *env, int regno,
struct bpf_call_arg_meta *meta)
{
struct bpf_reg_state *regs = cur_regs(env), *reg = &regs[regno];
const char *buf_info;
u32 *max_access;
switch (base_type(reg->type)) {
@ -4883,15 +4879,13 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
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,