netfilter: xtables: compute exact size needed for jumpstack

[firefly-linux-kernel-4.4.55.git] / net / ipv4 / netfilter / ip_tables.c

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 6c72fbb7b49eb97d3574fd8c10174f9580752911..5e44b35a8de82857d74c9e396c9a616ddedfbef3 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -439,11 +439,15 @@ ipt_do_table(struct sk_buff *skb,
 }
 
 /* Figures out from what hook each rule can be called: returns 0 if
-   there are loops.  Puts hook bitmask in comefrom. */
+ * there are loops.  Puts hook bitmask in comefrom.
+ *
+ * Keeps track of largest call depth seen and stores it in newinfo->stacksize.
+ */
 static int
-mark_source_chains(const struct xt_table_info *newinfo,
+mark_source_chains(struct xt_table_info *newinfo,
                   unsigned int valid_hooks, void *entry0)
 {
+       unsigned int calldepth, max_calldepth = 0;
        unsigned int hook;
 
        /* No recursion; use packet counter to save back ptrs (reset
@@ -457,6 +461,7 @@ mark_source_chains(const struct xt_table_info *newinfo,
 
                /* Set initial back pointer. */
                e->counters.pcnt = pos;
+               calldepth = 0;
 
                for (;;) {
                        const struct xt_standard_target *t
@@ -518,6 +523,9 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                        (entry0 + pos + size);
                                e->counters.pcnt = pos;
                                pos += size;
+                               WARN_ON_ONCE(calldepth == 0);
+                               if (calldepth > 0)
+                                       --calldepth;
                        } else {
                                int newpos = t->verdict;
 
@@ -531,9 +539,14 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                                                newpos);
                                                return 0;
                                        }
+                                       if (entry0 + newpos != ipt_next_entry(e) &&
+                                           !(e->ip.flags & IPT_F_GOTO) &&
+                                           ++calldepth > max_calldepth)
+                                               max_calldepth = calldepth;
+
                                        /* This a jump; chase it. */
-                                       duprintf("Jump rule %u -> %u\n",
-                                                pos, newpos);
+                                       duprintf("Jump rule %u -> %u, calldepth %d\n",
+                                                pos, newpos, calldepth);
                                } else {
                                        /* ... this is a fallthru */
                                        newpos = pos + e->next_offset;
@@ -547,6 +560,7 @@ mark_source_chains(const struct xt_table_info *newinfo,
                next:
                duprintf("Finished chain %u\n", hook);
        }
+       newinfo->stacksize = max_calldepth;
        return 1;
 }
 
@@ -826,9 +840,6 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0,
                if (ret != 0)
                        return ret;
                ++i;
-               if (strcmp(ipt_get_target(iter)->u.user.name,
-                   XT_ERROR_TARGET) == 0)
-                       ++newinfo->stacksize;
        }
 
        if (i != repl->num_entries) {
@@ -1744,9 +1755,6 @@ translate_compat_table(struct net *net,
                if (ret != 0)
                        break;
                ++i;
-               if (strcmp(ipt_get_target(iter1)->u.user.name,
-                   XT_ERROR_TARGET) == 0)
-                       ++newinfo->stacksize;
        }
        if (ret) {
                /*