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bpf: teach verifier to track stack depth 

teach verifier to track bpf program stack depth

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2017-05-30 13:31:29 -07:00 committed by David S. Miller
parent f696b8f471
commit 8726679a0f
2 changed files with 10 additions and 1 deletions
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1
include/linux/bpf.h
View File

@ -171,6 +171,7 @@ struct bpf_prog_aux {
atomic_t refcnt;
u32 used_map_cnt;
u32 max_ctx_offset;
u32 stack_depth;
struct latch_tree_node ksym_tnode;
struct list_head ksym_lnode;
const struct bpf_verifier_ops *ops;

10
kernel/bpf/verifier.c
View File

@ -926,6 +926,10 @@ static int check_mem_access(struct bpf_verifier_env *env, u32 regno, int off,
verbose("invalid stack off=%d size=%d\n", off, size);
return -EACCES;
}
if (env->prog->aux->stack_depth < -off)
env->prog->aux->stack_depth = -off;
if (t == BPF_WRITE) {
if (!env->allow_ptr_leaks &&
state->stack_slot_type[MAX_BPF_STACK + off] == STACK_SPILL &&
@ -1032,6 +1036,9 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
return -EACCES;
}
if (env->prog->aux->stack_depth < -off)
env->prog->aux->stack_depth = -off;
if (meta && meta->raw_mode) {
meta->access_size = access_size;
meta->regno = regno;
@ -3167,7 +3174,8 @@ process_bpf_exit:
insn_idx++;
}
verbose("processed %d insns\n", insn_processed);
verbose("processed %d insns, stack depth %d\n",
insn_processed, env->prog->aux->stack_depth);
return 0;
}