[PATCHv4 bpf-next 08/25] bpf: Move sleepable verification code to btf_id_allow_sleepable

[Jiri Olsa <jolsa@kernel.org>]

Move sleepable verification code to btf_id_allow_sleepable function.
It will be used in following changes.

Adding code to retrieve type's name instead of passing it from
bpf_check_attach_target function, because this function will be
called from another place in following changes and it's easier
to retrieve the name directly in here.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/bpf_verifier.h |  3 ++
 kernel/bpf/verifier.c        | 79 +++++++++++++++++++++---------------
 2 files changed, 50 insertions(+), 32 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 090aa26d1c98..186726fcf52a 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -932,6 +932,9 @@ static inline void bpf_trampoline_unpack_key(u64 key, u32 *obj_id, u32 *btf_id)
 		*btf_id = key & 0x7FFFFFFF;
 }
 
+int btf_id_allow_sleepable(u32 btf_id, unsigned long addr, const struct bpf_prog *prog,
+			   const struct btf *btf);
+
 int bpf_check_attach_target(struct bpf_verifier_log *log,
 			    const struct bpf_prog *prog,
 			    const struct bpf_prog *tgt_prog,
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 498132da12e7..0be54f500c66 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -25087,6 +25087,52 @@ static bool is_tracing_multi_id(const struct bpf_prog *prog, u32 btf_id)
 	return is_tracing_multi(prog->expected_attach_type) && bpf_multi_func_btf_id[0] == btf_id;
 }
 
+int btf_id_allow_sleepable(u32 btf_id, unsigned long addr, const struct bpf_prog *prog,
+			   const struct btf *btf)
+{
+	const struct btf_type *t;
+	const char *tname;
+
+	switch (prog->type) {
+	case BPF_PROG_TYPE_TRACING:
+		t = btf_type_by_id(btf, btf_id);
+		if (!t)
+			return -EINVAL;
+		tname = btf_name_by_offset(btf, t->name_off);
+		if (!tname)
+			return -EINVAL;
+
+		/* *.multi sleepable programs will pass initial sleepable check,
+		 * the actual attached btf ids are checked later during the link
+		 * attachment.
+		 */
+		if (is_tracing_multi_id(prog, btf_id))
+			return 0;
+		if (!check_attach_sleepable(btf_id, addr, tname))
+			return 0;
+		/* fentry/fexit/fmod_ret progs can also be sleepable if they are
+		 * in the fmodret id set with the KF_SLEEPABLE flag.
+		 */
+		else {
+			u32 *flags = btf_kfunc_is_modify_return(btf, btf_id, prog);
+
+			if (flags && (*flags & KF_SLEEPABLE))
+				return 0;
+		}
+		break;
+	case BPF_PROG_TYPE_LSM:
+		/* LSM progs check that they are attached to bpf_lsm_*() funcs.
+		 * Only some of them are sleepable.
+		 */
+		if (bpf_lsm_is_sleepable_hook(btf_id))
+			return 0;
+		break;
+	default:
+		break;
+	}
+	return -EINVAL;
+}
+
 int bpf_check_attach_target(struct bpf_verifier_log *log,
 			    const struct bpf_prog *prog,
 			    const struct bpf_prog *tgt_prog,
@@ -25377,38 +25423,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 		}
 
 		if (prog->sleepable) {
-			ret = -EINVAL;
-			switch (prog->type) {
-			case BPF_PROG_TYPE_TRACING:
-				/* *.multi sleepable programs will pass initial sleepable check,
-				 * the actual attached btf ids are checked later during the link
-				 * attachment.
-				 */
-				if (is_tracing_multi_id(prog, btf_id))
-					ret = 0;
-				if (!check_attach_sleepable(btf_id, addr, tname))
-					ret = 0;
-				/* fentry/fexit/fmod_ret progs can also be sleepable if they are
-				 * in the fmodret id set with the KF_SLEEPABLE flag.
-				 */
-				else {
-					u32 *flags = btf_kfunc_is_modify_return(btf, btf_id,
-										prog);
-
-					if (flags && (*flags & KF_SLEEPABLE))
-						ret = 0;
-				}
-				break;
-			case BPF_PROG_TYPE_LSM:
-				/* LSM progs check that they are attached to bpf_lsm_*() funcs.
-				 * Only some of them are sleepable.
-				 */
-				if (bpf_lsm_is_sleepable_hook(btf_id))
-					ret = 0;
-				break;
-			default:
-				break;
-			}
+			ret = btf_id_allow_sleepable(btf_id, addr, prog, btf);
 			if (ret) {
 				module_put(mod);
 				bpf_log(log, "%s is not sleepable\n", tname);
-- 
2.53.0