[PATCH bpf-next 1/4] bpf: introduce verifier internal test flag

[Alexei Starovoitov]

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

Signed-off-by: Alexei Starovoitov <a...@kernel.org>
---
 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(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 5fe99f322b1c..26a6d58ca78c 100644
--- 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;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b5889257cc33..5d2fb183ee2d 100644
--- 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:
  *
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c0f62fd67c6b..ca60eafa6922 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1629,6 +1629,7 @@ static int bpf_prog_load(union bpf_attr *attr, union 
bpf_attr __user *uattr)
 
        if (attr->prog_flags & ~(BPF_F_STRICT_ALIGNMENT |
                                 BPF_F_ANY_ALIGNMENT |
+                                BPF_F_TEST_STATE_FREQ |
                                 BPF_F_TEST_RND_HI32))
                return -EINVAL;
 
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 16d66bd7af09..3fb50757e812 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7223,7 +7223,7 @@ static int is_state_visited(struct bpf_verifier_env *env, 
int insn_idx)
        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)
@@ -9263,6 +9263,9 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr 
*attr,
 
        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;
-- 
2.20.0