summaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
authorJiong Wang <jiong.wang@netronome.com>2018-05-02 16:17:19 -0400
committerDaniel Borkmann <daniel@iogearbox.net>2018-05-04 11:58:36 +0200
commit4cb3d99c84ccbf728ff0e381c7c9815c3fa2bd5e (patch)
treed6a6c3f464d0a9588f678b61dca9b9d81e670263 /kernel
parent9c8105bd4402236b1bb0f8f10709c5cec1440a0c (diff)
downloadlinux-4cb3d99c84ccbf728ff0e381c7c9815c3fa2bd5e.tar.gz
linux-4cb3d99c84ccbf728ff0e381c7c9815c3fa2bd5e.tar.bz2
linux-4cb3d99c84ccbf728ff0e381c7c9815c3fa2bd5e.zip
bpf: add faked "ending" subprog
There are quite a few code snippet like the following in verifier: subprog_start = 0; if (env->subprog_cnt == cur_subprog + 1) subprog_end = insn_cnt; else subprog_end = env->subprog_info[cur_subprog + 1].start; The reason is there is no marker in subprog_info array to tell the end of it. We could resolve this issue by introducing a faked "ending" subprog. The special "ending" subprog is with "insn_cnt" as start offset, so it is serving as the end mark whenever we iterate over all subprogs. Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c34
1 files changed, 14 insertions, 20 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5b293b4abb70..37e0affa515e 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -769,7 +769,7 @@ static int add_subprog(struct bpf_verifier_env *env, int off)
ret = find_subprog(env, off);
if (ret >= 0)
return 0;
- if (env->subprog_cnt > BPF_MAX_SUBPROGS) {
+ if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
verbose(env, "too many subprograms\n");
return -E2BIG;
}
@@ -810,16 +810,18 @@ static int check_subprogs(struct bpf_verifier_env *env)
return ret;
}
+ /* Add a fake 'exit' subprog which could simplify subprog iteration
+ * logic. 'subprog_cnt' should not be increased.
+ */
+ subprog[env->subprog_cnt].start = insn_cnt;
+
if (env->log.level > 1)
for (i = 0; i < env->subprog_cnt; i++)
verbose(env, "func#%d @%d\n", i, subprog[i].start);
/* now check that all jumps are within the same subprog */
- subprog_start = 0;
- if (env->subprog_cnt == cur_subprog + 1)
- subprog_end = insn_cnt;
- else
- subprog_end = subprog[cur_subprog + 1].start;
+ subprog_start = subprog[cur_subprog].start;
+ subprog_end = subprog[cur_subprog + 1].start;
for (i = 0; i < insn_cnt; i++) {
u8 code = insn[i].code;
@@ -843,11 +845,9 @@ next:
verbose(env, "last insn is not an exit or jmp\n");
return -EINVAL;
}
- cur_subprog++;
subprog_start = subprog_end;
- if (env->subprog_cnt == cur_subprog + 1)
- subprog_end = insn_cnt;
- else
+ cur_subprog++;
+ if (cur_subprog < env->subprog_cnt)
subprog_end = subprog[cur_subprog + 1].start;
}
}
@@ -1502,7 +1502,6 @@ static int check_max_stack_depth(struct bpf_verifier_env *env)
int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
struct bpf_subprog_info *subprog = env->subprog_info;
struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
int ret_insn[MAX_CALL_FRAMES];
int ret_prog[MAX_CALL_FRAMES];
@@ -1517,10 +1516,7 @@ process_func:
return -EACCES;
}
continue_func:
- if (env->subprog_cnt == idx + 1)
- subprog_end = insn_cnt;
- else
- subprog_end = subprog[idx + 1].start;
+ subprog_end = subprog[idx + 1].start;
for (; i < subprog_end; i++) {
if (insn[i].code != (BPF_JMP | BPF_CALL))
continue;
@@ -5141,7 +5137,8 @@ static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len
if (len == 1)
return;
- for (i = 0; i < env->subprog_cnt; i++) {
+ /* NOTE: fake 'exit' subprog should be updated as well. */
+ for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start < off)
continue;
env->subprog_info[i].start += len - 1;
@@ -5339,10 +5336,7 @@ static int jit_subprogs(struct bpf_verifier_env *env)
for (i = 0; i < env->subprog_cnt; i++) {
subprog_start = subprog_end;
- if (env->subprog_cnt == i + 1)
- subprog_end = prog->len;
- else
- subprog_end = env->subprog_info[i + 1].start;
+ subprog_end = env->subprog_info[i + 1].start;
len = subprog_end - subprog_start;
func[i] = bpf_prog_alloc(bpf_prog_size(len), GFP_USER);