mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-16 11:21:26 -04:00
Code Issues Packages Projects Releases Wiki Activity

bpf: Extract program_returns_void() for clarity

Browse Source 
From: Eduard Zingerman <eddyz87@gmail.com>

The check_return_code function has explicit checks on whether
a program type can return void. Factor this logic out to reuse
it later for both main progs and subprogs.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260228184759.108145-3-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman
2026-02-28 13:47:56 -05:00
committed by Alexei Starovoitov
parent 83419c8fdb
commit 63ec296239
1 changed files with 36 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
kernel/bpf/verifier.c
View File

@@ -17953,6 +17953,28 @@ static bool return_retval_range(struct bpf_verifier_env *env, struct bpf_retval_
return true;
}
static bool program_returns_void(struct bpf_verifier_env *env)
{
const struct bpf_prog *prog = env->prog;
enum bpf_prog_type prog_type = resolve_prog_type(prog);
switch (prog_type) {
case BPF_PROG_TYPE_LSM:
/* See return_retval_range, for BPF_LSM_CGROUP can be 0 or 0-1 depending on hook. */
if (prog->expected_attach_type != BPF_LSM_CGROUP &&
!prog->aux->attach_func_proto->type)
return true;
break;
case BPF_PROG_TYPE_STRUCT_OPS:
if (!prog->aux->attach_func_proto->type)
return true;
break;
default:
break;
}
return false;
}
static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name)
{
const char *exit_ctx = "At program exit";
@@ -17968,35 +17990,21 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char
/* LSM and struct_ops func-ptr's return type could be "void" */
if (!is_subprog || frame->in_exception_callback_fn) {
switch (prog_type) {
case BPF_PROG_TYPE_LSM:
if (prog->expected_attach_type == BPF_LSM_CGROUP)
/* See return_retval_range, can be 0 or 0-1 depending on hook. */
break;
if (!prog->aux->attach_func_proto->type)
return 0;
break;
case BPF_PROG_TYPE_STRUCT_OPS:
if (!prog->aux->attach_func_proto->type)
return 0;
if (program_returns_void(env))
return 0;
}
if (frame->in_exception_callback_fn)
break;
/* Allow a struct_ops program to return a referenced kptr if it
* matches the operator's return type and is in its unmodified
* form. A scalar zero (i.e., a null pointer) is also allowed.
*/
reg_type = reg->btf ? btf_type_by_id(reg->btf, reg->btf_id) : NULL;
ret_type = btf_type_resolve_ptr(prog->aux->attach_btf,
prog->aux->attach_func_proto->type,
NULL);
if (ret_type && ret_type == reg_type && reg->ref_obj_id)
return __check_ptr_off_reg(env, reg, regno, false);
break;
default:
break;
}
if (!is_subprog && prog_type == BPF_PROG_TYPE_STRUCT_OPS) {
/* Allow a struct_ops program to return a referenced kptr if it
* matches the operator's return type and is in its unmodified
* form. A scalar zero (i.e., a null pointer) is also allowed.
*/
reg_type = reg->btf ? btf_type_by_id(reg->btf, reg->btf_id) : NULL;
ret_type = btf_type_resolve_ptr(prog->aux->attach_btf,
prog->aux->attach_func_proto->type,
NULL);
if (ret_type && ret_type == reg_type && reg->ref_obj_id)
return __check_ptr_off_reg(env, reg, regno, false);
}
/* eBPF calling convention is such that R0 is used