2 files changed, 70 insertions, 5 deletions

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index c736945be7c5..548dcbdb7111 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -224,6 +224,7 @@ struct bpf_verifier_env {
         bool allow_ptr_leaks;
         bool seen_direct_write;
         struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */
+        const struct bpf_line_info *prev_linfo;
         struct bpf_verifier_log log;
         struct bpf_subprog_info subprog_info[BPF_MAX_SUBPROGS + 1];
         u32 subprog_cnt;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 89ce2613fdb0..ba8e3134bbc2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -26,6 +26,7 @@
 #include <linux/bsearch.h>
 #include <linux/sort.h>
 #include <linux/perf_event.h>
+#include <linux/ctype.h>
 
 #include "disasm.h"
 
@@ -216,6 +217,27 @@ struct bpf_call_arg_meta {
 
 static DEFINE_MUTEX(bpf_verifier_lock);
 
+static const struct bpf_line_info *
+find_linfo(const struct bpf_verifier_env *env, u32 insn_off)
+{
+        const struct bpf_line_info *linfo;
+        const struct bpf_prog *prog;
+        u32 i, nr_linfo;
+
+        prog = env->prog;
+        nr_linfo = prog->aux->nr_linfo;
+
+        if (!nr_linfo || insn_off >= prog->len)
+                return NULL;
+
+        linfo = prog->aux->linfo;
+        for (i = 1; i < nr_linfo; i++)
+                if (insn_off < linfo[i].insn_off)
+                        break;
+
+        return &linfo[i - 1];
+}
+
 void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
                        va_list args)
 {
@@ -266,6 +288,42 @@ __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
         va_end(args);
 }
 
+static const char *ltrim(const char *s)
+{
+        while (isspace(*s))
+                s++;
+
+        return s;
+}
+
+__printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env,
+                                         u32 insn_off,
+                                         const char *prefix_fmt, ...)
+{
+        const struct bpf_line_info *linfo;
+
+        if (!bpf_verifier_log_needed(&env->log))
+                return;
+
+        linfo = find_linfo(env, insn_off);
+        if (!linfo || linfo == env->prev_linfo)
+                return;
+
+        if (prefix_fmt) {
+                va_list args;
+
+                va_start(args, prefix_fmt);
+                bpf_verifier_vlog(&env->log, prefix_fmt, args);
+                va_end(args);
+        }
+
+        verbose(env, "%s\n",
+                ltrim(btf_name_by_offset(env->prog->aux->btf,
+                                         linfo->line_off)));
+
+        env->prev_linfo = linfo;
+}
+
 static bool type_is_pkt_pointer(enum bpf_reg_type type)
 {
         return type == PTR_TO_PACKET ||
@@ -4561,6 +4619,7 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
                 return 0;
 
         if (w < 0 || w >= env->prog->len) {
+                verbose_linfo(env, t, "%d: ", t);
                 verbose(env, "jump out of range from insn %d to %d\n", t, w);
                 return -EINVAL;
         }
@@ -4578,6 +4637,8 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env)
                 insn_stack[cur_stack++] = w;
                 return 1;
         } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
+                verbose_linfo(env, t, "%d: ", t);
+                verbose_linfo(env, w, "%d: ", w);
                 verbose(env, "back-edge from insn %d to %d\n", t, w);
                 return -EINVAL;
         } else if (insn_state[w] == EXPLORED) {
@@ -4600,10 +4661,6 @@ static int check_cfg(struct bpf_verifier_env *env)
         int ret = 0;
         int i, t;
 
-        ret = check_subprogs(env);
-        if (ret < 0)
-                return ret;
-
         insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
         if (!insn_state)
                 return -ENOMEM;
@@ -5448,6 +5505,8 @@ static int do_check(struct bpf_verifier_env *env)
         int insn_processed = 0;
         bool do_print_state = false;
 
+        env->prev_linfo = NULL;
+
         state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
         if (!state)
                 return -ENOMEM;
@@ -5521,6 +5580,7 @@ static int do_check(struct bpf_verifier_env *env)
                                 .private_data   = env,
                         };
 
+                        verbose_linfo(env, insn_idx, "; ");
                         verbose(env, "%d: ", insn_idx);
                         print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
                 }
@@ -6755,7 +6815,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 
         env->allow_ptr_leaks = capable(CAP_SYS_ADMIN);
 
-        ret = check_cfg(env);
+        ret = check_subprogs(env);
         if (ret < 0)
                 goto skip_full_check;
 
@@ -6763,6 +6823,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
         if (ret < 0)
                 goto skip_full_check;
 
+        ret = check_cfg(env);
+        if (ret < 0)
+                goto skip_full_check;
+
         ret = do_check(env);
         if (env->cur_state) {
                 free_verifier_state(env->cur_state, true);