From: Amery Hung <ameryhung@gmail.com>
To: bpf@vger.kernel.org
Cc: alexei.starovoitov@gmail.com, andrii@kernel.org,
daniel@iogearbox.net, eddyz87@gmail.com, memxor@gmail.com,
ameryhung@gmail.com, kernel-team@meta.com
Subject: [PATCH bpf-next v2 02/23] bpf: Address check_func_arg() arguments by argno
Date: Fri, 11 Sep 2026 15:03:54 -0700 [thread overview]
Message-ID: <20260911220415.1396439-3-ameryhung@gmail.com> (raw)
In-Reply-To: <20260911220415.1396439-1-ameryhung@gmail.com>
check_func_arg() derives every argument from BPF_REG_1 + arg. That works
for helpers, which have at most five arguments, but kfunc arguments
beyond the fifth are passed on the stack.
Switch to the argno_t addressing used by check_kfunc_args(): obtain
argument state with get_func_arg_reg(), use argno for diagnostics, and
call check_reg_arg() only when the argument is held in a register. This
prepares check_func_arg() to be shared with kfunc verification.
There is no functional change for helpers. reg_arg_name() renders their
register arguments as R%d, so the updated diagnostics remain unchanged.
Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
kernel/bpf/verifier.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a45e0478f23c..d5e885435bb6 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8815,10 +8815,12 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
int insn_idx)
{
const struct bpf_func_proto *fn = meta->fn;
- u32 regno = BPF_REG_1 + arg;
- struct bpf_reg_state *reg = reg_state(env, regno);
+ struct bpf_func_state *caller = cur_func(env);
+ struct bpf_reg_state *regs = cur_regs(env);
+ argno_t argno = argno_from_arg(arg + 1);
+ struct bpf_reg_state *reg = get_func_arg_reg(caller, regs, arg);
enum bpf_arg_type arg_type = fn->arg_type[arg];
- argno_t argno = argno_from_reg(regno);
+ int regno = reg_from_argno(argno);
enum bpf_reg_type type = reg->type;
u32 *arg_btf_id = NULL;
u32 key_size;
@@ -8827,14 +8829,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
if (arg_type == ARG_DONTCARE)
return 0;
- err = check_reg_arg(env, regno, SRC_OP);
- if (err)
- return err;
+ if (regno >= 0) {
+ err = check_reg_arg(env, regno, SRC_OP);
+ if (err)
+ return err;
+ }
if (arg_type == ARG_ANYTHING) {
- if (is_pointer_value(env, regno)) {
- verbose(env, "R%d leaks addr into helper function\n",
- regno);
+ if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
+ verbose(env, "%s leaks addr into helper function\n",
+ reg_arg_name(env, argno));
return -EACCES;
}
return 0;
@@ -8954,7 +8958,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
break;
case ARG_PTR_TO_PERCPU_BTF_ID:
if (!reg->btf_id) {
- verbose(env, "Helper has invalid btf_id in R%d\n", regno);
+ verbose(env, "Helper has invalid btf_id in %s\n", reg_arg_name(env, argno));
return -EACCES;
}
meta->ret_btf = reg->btf;
@@ -8991,7 +8995,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
* next is_mem_size argument below.
*/
if (arg_type & MEM_FIXED_SIZE) {
- err = check_mem_reg(env, reg, argno_from_reg(regno), fn->arg_size[arg],
+ err = check_mem_reg(env, reg, argno, fn->arg_size[arg],
arg_type & MEM_WRITE ? BPF_WRITE : BPF_READ, meta, NULL);
if (err)
return err;
@@ -9000,14 +9004,14 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
}
break;
case ARG_MEM_SIZE:
- err = check_mem_size_reg(env, reg_state(env, regno - 1), reg,
- argno_from_reg(regno - 1), argno,
+ err = check_mem_size_reg(env, get_func_arg_reg(caller, regs, arg - 1), reg,
+ argno_from_arg(arg), argno,
fn->arg_type[arg - 1] & MEM_WRITE ? BPF_WRITE : BPF_READ,
false, meta, NULL);
break;
case ARG_MEM_SIZE_OR_ZERO:
- err = check_mem_size_reg(env, reg_state(env, regno - 1), reg,
- argno_from_reg(regno - 1), argno,
+ err = check_mem_size_reg(env, get_func_arg_reg(caller, regs, arg - 1), reg,
+ argno_from_arg(arg), argno,
fn->arg_type[arg - 1] & MEM_WRITE ? BPF_WRITE : BPF_READ,
true, meta, NULL);
break;
--
2.52.0
next prev parent reply other threads:[~2026-09-11 22:04 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 22:03 [PATCH bpf-next v2 00/23] Unify helper and kfunc argument checks Amery Hung
2026-09-11 22:03 ` [PATCH bpf-next v2 01/23] bpf: Pass call metadata through shared " Amery Hung
2026-09-11 22:03 ` Amery Hung [this message]
2026-09-11 22:03 ` [PATCH bpf-next v2 03/23] bpf: Only compare func_id against BPF_FUNC_* for helper calls Amery Hung
2026-09-11 22:03 ` [PATCH bpf-next v2 04/23] bpf: Only compare func_id against kfunc BTF IDs for kfunc calls Amery Hung
2026-09-11 22:03 ` [PATCH bpf-next v2 05/23] bpf: Clarify unused and scalar function argument types Amery Hung
2026-09-11 22:19 ` sashiko-bot
2026-09-11 22:03 ` [PATCH bpf-next v2 06/23] bpf: Unify kfunc argument kinds with enum bpf_arg_type Amery Hung
2026-09-11 22:26 ` sashiko-bot
2026-09-11 22:03 ` [PATCH bpf-next v2 07/23] bpf: Classify kfunc arguments the verifier ignores Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 08/23] bpf: Align helper and kfunc ARG_PTR_TO_PROG_AUX handling Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 09/23] bpf: Set OBJ_RELEASE when generating kfunc argument types Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 10/23] bpf: Set MEM_UNINIT and dynptr subtypes when generating kfunc arg types Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 11/23] bpf: Set MEM_RCU when generating kfunc argument types Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 12/23] bpf: Resolve BTF ID of ARG_PTR_TO_BTF_ID in kfunc bpf_func_proto Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 13/23] bpf: Resolve ARG_PTR_TO_MEM | MEM_FIXED_SIZE size " Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 14/23] bpf: Consolidate runtime argument type resolution Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 15/23] bpf: Consolidate nullable argument validation Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 16/23] bpf: Drop redundant BTF pointer helper write rejection Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 17/23] bpf: Consolidate helper and kfunc PTR_TO_BTF_ID argument matching Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 18/23] bpf: Admit kfunc argument registers through check_reg_type() Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 19/23] bpf: Consolidate function call pkt_access validation Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 20/23] selftests/bpf: Test kfunc packet memory direct writes Amery Hung
2026-09-11 22:36 ` sashiko-bot
2026-09-11 22:04 ` [PATCH bpf-next v2 21/23] bpf: Consolidate release argument validation Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 22/23] selftests/bpf: Test nullable per-CPU kptr identity after exchange Amery Hung
2026-09-11 22:04 ` [PATCH bpf-next v2 23/23] bpf: Check helper and kfunc arguments in one path Amery Hung
2026-09-12 3:20 ` [PATCH bpf-next v2 00/23] Unify helper and kfunc argument checks patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260911220415.1396439-3-ameryhung@gmail.com \
--to=ameryhung@gmail.com \
--cc=alexei.starovoitov@gmail.com \
--cc=andrii@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=kernel-team@meta.com \
--cc=memxor@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.