Revert "netfilter: x_tables: ensure last rule in base chain matches underflow/policy"

This reverts commit 0d7df906a0e78079a02108b06d32c3ef2238ad25.

Valdis Kletnieks reported that xtables is broken in linux-next since
0d7df906a0e78  ("netfilter: x_tables: ensure last rule in base chain
matches underflow/policy"), as kernel rejects the (well-formed) ruleset:

[   64.402790] ip6_tables: last base chain position 1136 doesn't match underflow 1344 (hook 1)

mark_source_chains is not the correct place for such a check, as it
terminates evaluation of a chain once it sees an unconditional verdict
(following rules are known to be unreachable). It seems preferrable to
fix libiptc instead, so remove this check again.

Fixes: 0d7df906a0e78 ("netfilter: x_tables: ensure last rule in base chain matches underflow/policy")
Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index f366ff1..aaafdbd 100644 (file)
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -309,13 +309,10 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
        for (hook = 0; hook < NF_ARP_NUMHOOKS; hook++) {
                unsigned int pos = newinfo->hook_entry[hook];
                struct arpt_entry *e = entry0 + pos;
-               unsigned int last_pos, depth;
 
                if (!(valid_hooks & (1 << hook)))
                        continue;
 
-               depth = 0;
-               last_pos = pos;
                /* Set initial back pointer. */
                e->counters.pcnt = pos;
 
@@ -346,8 +343,6 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
                                        pos = e->counters.pcnt;
                                        e->counters.pcnt = 0;
 
-                                       if (depth)
-                                               --depth;
                                        /* We're at the start. */
                                        if (pos == oldpos)
                                                goto next;
@@ -372,9 +367,6 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
                                        if (!xt_find_jump_offset(offsets, newpos,
                                                                 newinfo->number))
                                                return 0;
-
-                                       if (entry0 + newpos != arpt_next_entry(e))
-                                               ++depth;
                                } else {
                                        /* ... this is a fallthru */
                                        newpos = pos + e->next_offset;
@@ -385,15 +377,8 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
                                e->counters.pcnt = pos;
                                pos = newpos;
                        }
-                       if (depth == 0)
-                               last_pos = pos;
-               }
-next:
-               if (last_pos != newinfo->underflow[hook]) {
-                       pr_err_ratelimited("last base chain position %u doesn't match underflow %u (hook %u)\n",
-                                          last_pos, newinfo->underflow[hook], hook);
-                       return 0;
                }
+next:          ;
        }
        return 1;
 }

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 2362ca2..f906351 100644 (file)
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -378,13 +378,10 @@ mark_source_chains(const struct xt_table_info *newinfo,
        for (hook = 0; hook < NF_INET_NUMHOOKS; hook++) {
                unsigned int pos = newinfo->hook_entry[hook];
                struct ipt_entry *e = entry0 + pos;
-               unsigned int last_pos, depth;
 
                if (!(valid_hooks & (1 << hook)))
                        continue;
 
-               depth = 0;
-               last_pos = pos;
                /* Set initial back pointer. */
                e->counters.pcnt = pos;
 
@@ -413,8 +410,6 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                        pos = e->counters.pcnt;
                                        e->counters.pcnt = 0;
 
-                                       if (depth)
-                                               --depth;
                                        /* We're at the start. */
                                        if (pos == oldpos)
                                                goto next;
@@ -439,9 +434,6 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                        if (!xt_find_jump_offset(offsets, newpos,
                                                                 newinfo->number))
                                                return 0;
-
-                                       if (entry0 + newpos != ipt_next_entry(e))
-                                               ++depth;
                                } else {
                                        /* ... this is a fallthru */
                                        newpos = pos + e->next_offset;
@@ -452,15 +444,8 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                e->counters.pcnt = pos;
                                pos = newpos;
                        }
-                       if (depth == 0)
-                               last_pos = pos;
-               }
-next:
-               if (last_pos != newinfo->underflow[hook]) {
-                       pr_err_ratelimited("last base chain position %u doesn't match underflow %u (hook %u)\n",
-                                          last_pos, newinfo->underflow[hook], hook);
-                       return 0;
                }
+next:          ;
        }
        return 1;
 }

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 0045087..3c36a4c 100644 (file)
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -396,13 +396,10 @@ mark_source_chains(const struct xt_table_info *newinfo,
        for (hook = 0; hook < NF_INET_NUMHOOKS; hook++) {
                unsigned int pos = newinfo->hook_entry[hook];
                struct ip6t_entry *e = entry0 + pos;
-               unsigned int last_pos, depth;
 
                if (!(valid_hooks & (1 << hook)))
                        continue;
 
-               depth = 0;
-               last_pos = pos;
                /* Set initial back pointer. */
                e->counters.pcnt = pos;
 
@@ -431,8 +428,6 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                        pos = e->counters.pcnt;
                                        e->counters.pcnt = 0;
 
-                                       if (depth)
-                                               --depth;
                                        /* We're at the start. */
                                        if (pos == oldpos)
                                                goto next;
@@ -457,9 +452,6 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                        if (!xt_find_jump_offset(offsets, newpos,
                                                                 newinfo->number))
                                                return 0;
-
-                                       if (entry0 + newpos != ip6t_next_entry(e))
-                                               ++depth;
                                } else {
                                        /* ... this is a fallthru */
                                        newpos = pos + e->next_offset;
@@ -470,15 +462,8 @@ mark_source_chains(const struct xt_table_info *newinfo,
                                e->counters.pcnt = pos;
                                pos = newpos;
                        }
-                       if (depth == 0)
-                               last_pos = pos;
-               }
-next:
-               if (last_pos != newinfo->underflow[hook]) {
-                       pr_err_ratelimited("last base chain position %u doesn't match underflow %u (hook %u)\n",
-                                          last_pos, newinfo->underflow[hook], hook);
-                       return 0;
                }
+next:          ;
        }
        return 1;
 }