From: Alexei Starovoitov <ast@kernel.org>
Date: Thu, 22 Aug 2019 22:52:12 -0700
Subject: bpf: introduce verifier internal test flag
Patch-mainline: v5.4-rc1
Git-commit: 10d274e880eb208ec6a76261a9f8f8155020f771
References: bsc#1154353

Introduce BPF_F_TEST_STATE_FREQ flag to stress test parentage chain
and state pruning.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/bpf_verifier.h |    1 +
 include/uapi/linux/bpf.h     |    3 +++
 kernel/bpf/syscall.c         |    1 +
 kernel/bpf/verifier.c        |    5 ++++-
 4 files changed, 9 insertions(+), 1 deletion(-)

--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -355,6 +355,7 @@ struct bpf_verifier_env {
 	struct bpf_verifier_stack_elem *head; /* stack of verifier states to be processed */
 	int stack_size;			/* number of states to be processed */
 	bool strict_alignment;		/* perform strict pointer alignment checks */
+	bool test_state_freq;		/* test verifier with different pruning frequency */
 	struct bpf_verifier_state *cur_state; /* current verifier state */
 	struct bpf_verifier_state_list **explored_states; /* search pruning optimization */
 	struct bpf_verifier_state_list *free_list;
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -285,6 +285,9 @@ enum bpf_attach_type {
  */
 #define BPF_F_TEST_RND_HI32	(1U << 2)
 
+/* The verifier internal test flag. Behavior is undefined */
+#define BPF_F_TEST_STATE_FREQ	(1U << 3)
+
 /* When BPF ldimm64's insn[0].src_reg != 0 then this can have
  * two extensions:
  *
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1629,6 +1629,7 @@ static int bpf_prog_load(union bpf_attr
 
 	if (attr->prog_flags & ~(BPF_F_STRICT_ALIGNMENT |
 				 BPF_F_ANY_ALIGNMENT |
+				 BPF_F_TEST_STATE_FREQ |
 				 BPF_F_TEST_RND_HI32))
 		return -EINVAL;
 
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7228,7 +7228,7 @@ static int is_state_visited(struct bpf_v
 	struct bpf_verifier_state_list *sl, **pprev;
 	struct bpf_verifier_state *cur = env->cur_state, *new;
 	int i, j, err, states_cnt = 0;
-	bool add_new_state = false;
+	bool add_new_state = env->test_state_freq ? true : false;
 
 	cur->last_insn_idx = env->prev_insn_idx;
 	if (!env->insn_aux_data[insn_idx].prune_point)
@@ -9268,6 +9268,9 @@ int bpf_check(struct bpf_prog **prog, un
 
 	env->allow_ptr_leaks = is_priv;
 
+	if (is_priv)
+		env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
+
 	ret = replace_map_fd_with_map_ptr(env);
 	if (ret < 0)
 		goto skip_full_check;