From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Cong Wang <xiyou.wangcong@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com>,
Andrii Nakryiko <andrii@kernel.org>
Subject: [PATCH bpf-next v5 03/12] bpf: refactor check_func_call() to allow callback function
Date: Fri, 26 Feb 2021 12:49:23 -0800 [thread overview]
Message-ID: <20210226204923.3884627-1-yhs@fb.com> (raw)
In-Reply-To: <20210226204920.3884074-1-yhs@fb.com>
Later proposed bpf_for_each_map_elem() helper has callback
function as one of its arguments. This patch refactored
check_func_call() to permit callback function which sets
callee state. Different callback functions may have
different callee states.
There is no functionality change for this patch.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
---
kernel/bpf/verifier.c | 60 +++++++++++++++++++++++++++++++------------
1 file changed, 43 insertions(+), 17 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7194980c3ca4..97e772f44cd7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5249,13 +5249,19 @@ static void clear_caller_saved_regs(struct bpf_verifier_env *env,
}
}
-static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
- int *insn_idx)
+typedef int (*set_callee_state_fn)(struct bpf_verifier_env *env,
+ struct bpf_func_state *caller,
+ struct bpf_func_state *callee,
+ int insn_idx);
+
+static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
+ int *insn_idx, int subprog,
+ set_callee_state_fn set_callee_state_cb)
{
struct bpf_verifier_state *state = env->cur_state;
struct bpf_func_info_aux *func_info_aux;
struct bpf_func_state *caller, *callee;
- int i, err, subprog, target_insn;
+ int err;
bool is_global = false;
if (state->curframe + 1 >= MAX_CALL_FRAMES) {
@@ -5264,14 +5270,6 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
return -E2BIG;
}
- target_insn = *insn_idx + insn->imm;
- subprog = find_subprog(env, target_insn + 1);
- if (subprog < 0) {
- verbose(env, "verifier bug. No program starts at insn %d\n",
- target_insn + 1);
- return -EFAULT;
- }
-
caller = state->frame[state->curframe];
if (state->frame[state->curframe + 1]) {
verbose(env, "verifier bug. Frame %d already allocated\n",
@@ -5326,11 +5324,9 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
if (err)
return err;
- /* copy r1 - r5 args that callee can access. The copy includes parent
- * pointers, which connects us up to the liveness chain
- */
- for (i = BPF_REG_1; i <= BPF_REG_5; i++)
- callee->regs[i] = caller->regs[i];
+ err = set_callee_state_cb(env, caller, callee, *insn_idx);
+ if (err)
+ return err;
clear_caller_saved_regs(env, caller->regs);
@@ -5338,7 +5334,7 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
state->curframe++;
/* and go analyze first insn of the callee */
- *insn_idx = target_insn;
+ *insn_idx = env->subprog_info[subprog].start - 1;
if (env->log.level & BPF_LOG_LEVEL) {
verbose(env, "caller:\n");
@@ -5349,6 +5345,36 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
return 0;
}
+static int set_callee_state(struct bpf_verifier_env *env,
+ struct bpf_func_state *caller,
+ struct bpf_func_state *callee, int insn_idx)
+{
+ int i;
+
+ /* copy r1 - r5 args that callee can access. The copy includes parent
+ * pointers, which connects us up to the liveness chain
+ */
+ for (i = BPF_REG_1; i <= BPF_REG_5; i++)
+ callee->regs[i] = caller->regs[i];
+ return 0;
+}
+
+static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
+ int *insn_idx)
+{
+ int subprog, target_insn;
+
+ target_insn = *insn_idx + insn->imm + 1;
+ subprog = find_subprog(env, target_insn);
+ if (subprog < 0) {
+ verbose(env, "verifier bug. No program starts at insn %d\n",
+ target_insn);
+ return -EFAULT;
+ }
+
+ return __check_func_call(env, insn, insn_idx, subprog, set_callee_state);
+}
+
static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
{
struct bpf_verifier_state *state = env->cur_state;
--
2.24.1
next prev parent reply other threads:[~2021-02-26 20:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 20:49 [PATCH bpf-next v5 00/12] bpf: add bpf_for_each_map_elem() helper Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 01/12] bpf: factor out visit_func_call_insn() in check_cfg() Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 02/12] bpf: factor out verbose_invalid_scalar() Yonghong Song
2021-02-26 20:49 ` Yonghong Song [this message]
2021-02-26 20:49 ` [PATCH bpf-next v5 04/12] bpf: change return value of verifier function add_subprog() Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 05/12] bpf: add bpf_for_each_map_elem() helper Yonghong Song
2021-02-26 21:29 ` Alexei Starovoitov
2021-02-26 20:49 ` [PATCH bpf-next v5 06/12] bpf: add hashtab support for " Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 07/12] bpf: add arraymap " Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 08/12] libbpf: move function is_ldimm64() earlier in libbpf.c Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 09/12] libbpf: support subprog address relocation Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 10/12] bpftool: print subprog address properly Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 11/12] selftests/bpf: add hashmap test for bpf_for_each_map_elem() helper Yonghong Song
2021-02-26 20:49 ` [PATCH bpf-next v5 12/12] selftests/bpf: add arraymap " Yonghong Song
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