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authorJakub Kicinski <jakub.kicinski@netronome.com>2016-09-21 11:43:58 +0100
committerDavid S. Miller <davem@davemloft.net>2016-09-21 19:50:02 -0400
commit13a27dfc669724564aafa2699976ee756029fed2 (patch)
tree716dc81499b54b9bad19483ddc9a39c09210bbc9 /kernel/bpf
parent58e2af8b3a6b587e4ac8414343581da4349d3c0f (diff)
downloadlinux-13a27dfc669724564aafa2699976ee756029fed2.tar.bz2
bpf: enable non-core use of the verfier
Advanced JIT compilers and translators may want to use eBPF verifier as a base for parsers or to perform custom checks and validations. Add ability for external users to invoke the verifier and provide callbacks to be invoked for every intruction checked. For now only add most basic callback for per-instruction pre-interpretation checks is added. More advanced users may also like to have per-instruction post callback and state comparison callback. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index dca2b9b1d02e..ee86a77dc40b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -632,6 +632,10 @@ static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
static int check_ctx_access(struct bpf_verifier_env *env, int off, int size,
enum bpf_access_type t, enum bpf_reg_type *reg_type)
{
+ /* for analyzer ctx accesses are already validated and converted */
+ if (env->analyzer_ops)
+ return 0;
+
if (env->prog->aux->ops->is_valid_access &&
env->prog->aux->ops->is_valid_access(off, size, t, reg_type)) {
/* remember the offset of last byte accessed in ctx */
@@ -2225,6 +2229,15 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
return 0;
}
+static int ext_analyzer_insn_hook(struct bpf_verifier_env *env,
+ int insn_idx, int prev_insn_idx)
+{
+ if (!env->analyzer_ops || !env->analyzer_ops->insn_hook)
+ return 0;
+
+ return env->analyzer_ops->insn_hook(env, insn_idx, prev_insn_idx);
+}
+
static int do_check(struct bpf_verifier_env *env)
{
struct bpf_verifier_state *state = &env->cur_state;
@@ -2283,6 +2296,10 @@ static int do_check(struct bpf_verifier_env *env)
print_bpf_insn(insn);
}
+ err = ext_analyzer_insn_hook(env, insn_idx, prev_insn_idx);
+ if (err)
+ return err;
+
if (class == BPF_ALU || class == BPF_ALU64) {
err = check_alu_op(env, insn);
if (err)
@@ -2845,3 +2862,54 @@ err_free_env:
kfree(env);
return ret;
}
+
+int bpf_analyzer(struct bpf_prog *prog, const struct bpf_ext_analyzer_ops *ops,
+ void *priv)
+{
+ struct bpf_verifier_env *env;
+ int ret;
+
+ env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
+ if (!env)
+ return -ENOMEM;
+
+ env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) *
+ prog->len);
+ ret = -ENOMEM;
+ if (!env->insn_aux_data)
+ goto err_free_env;
+ env->prog = prog;
+ env->analyzer_ops = ops;
+ env->analyzer_priv = priv;
+
+ /* grab the mutex to protect few globals used by verifier */
+ mutex_lock(&bpf_verifier_lock);
+
+ log_level = 0;
+
+ env->explored_states = kcalloc(env->prog->len,
+ sizeof(struct bpf_verifier_state_list *),
+ GFP_KERNEL);
+ ret = -ENOMEM;
+ if (!env->explored_states)
+ goto skip_full_check;
+
+ ret = check_cfg(env);
+ if (ret < 0)
+ goto skip_full_check;
+
+ env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
+
+ ret = do_check(env);
+
+skip_full_check:
+ while (pop_stack(env, NULL) >= 0);
+ free_states(env);
+
+ mutex_unlock(&bpf_verifier_lock);
+ vfree(env->insn_aux_data);
+err_free_env:
+ kfree(env);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(bpf_analyzer);