[NETFILTER]: ip_tables: fix compat related crash
check_compat_entry_size_and_hooks iterates over the matches and calls
compat_check_calc_match, which loads the match and calculates the
compat offsets, but unlike the non-compat version, doesn't call
->checkentry yet. On error however it calls cleanup_matches, which in
turn calls ->destroy, which can result in crashes if the destroy
function (validly) expects to only get called after the checkentry
function.
Add a compat_release_match function that only drops the module reference
on error and rename compat_check_calc_match to compat_find_calc_match to
reflect the fact that it doesn't call the checkentry function.
Reported by Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: Dmitry Mishin <dim@openvz.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index e3f83bf..9bacf1a0 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -499,7 +499,8 @@
}
static inline int check_match(struct ipt_entry_match *m, const char *name,
- const struct ipt_ip *ip, unsigned int hookmask)
+ const struct ipt_ip *ip, unsigned int hookmask,
+ unsigned int *i)
{
struct xt_match *match;
int ret;
@@ -515,6 +516,8 @@
m->u.kernel.match->name);
ret = -EINVAL;
}
+ if (!ret)
+ (*i)++;
return ret;
}
@@ -537,11 +540,10 @@
}
m->u.kernel.match = match;
- ret = check_match(m, name, ip, hookmask);
+ ret = check_match(m, name, ip, hookmask, i);
if (ret)
goto err;
- (*i)++;
return 0;
err:
module_put(m->u.kernel.match->me);
@@ -1425,7 +1427,7 @@
}
static inline int
-compat_check_calc_match(struct ipt_entry_match *m,
+compat_find_calc_match(struct ipt_entry_match *m,
const char *name,
const struct ipt_ip *ip,
unsigned int hookmask,
@@ -1449,6 +1451,31 @@
}
static inline int
+compat_release_match(struct ipt_entry_match *m, unsigned int *i)
+{
+ if (i && (*i)-- == 0)
+ return 1;
+
+ module_put(m->u.kernel.match->me);
+ return 0;
+}
+
+static inline int
+compat_release_entry(struct ipt_entry *e, unsigned int *i)
+{
+ struct ipt_entry_target *t;
+
+ if (i && (*i)-- == 0)
+ return 1;
+
+ /* Cleanup all matches */
+ IPT_MATCH_ITERATE(e, compat_release_match, NULL);
+ t = ipt_get_target(e);
+ module_put(t->u.kernel.target->me);
+ return 0;
+}
+
+static inline int
check_compat_entry_size_and_hooks(struct ipt_entry *e,
struct xt_table_info *newinfo,
unsigned int *size,
@@ -1485,10 +1512,10 @@
off = 0;
entry_offset = (void *)e - (void *)base;
j = 0;
- ret = IPT_MATCH_ITERATE(e, compat_check_calc_match, name, &e->ip,
+ ret = IPT_MATCH_ITERATE(e, compat_find_calc_match, name, &e->ip,
e->comefrom, &off, &j);
if (ret != 0)
- goto cleanup_matches;
+ goto release_matches;
t = ipt_get_target(e);
target = try_then_request_module(xt_find_target(AF_INET,
@@ -1499,7 +1526,7 @@
duprintf("check_compat_entry_size_and_hooks: `%s' not found\n",
t->u.user.name);
ret = target ? PTR_ERR(target) : -ENOENT;
- goto cleanup_matches;
+ goto release_matches;
}
t->u.kernel.target = target;
@@ -1526,8 +1553,8 @@
out:
module_put(t->u.kernel.target->me);
-cleanup_matches:
- IPT_MATCH_ITERATE(e, cleanup_match, &j);
+release_matches:
+ IPT_MATCH_ITERATE(e, compat_release_match, &j);
return ret;
}
@@ -1574,15 +1601,26 @@
return ret;
}
-static inline int compat_check_entry(struct ipt_entry *e, const char *name)
+static inline int compat_check_entry(struct ipt_entry *e, const char *name,
+ unsigned int *i)
{
- int ret;
+ int j, ret;
- ret = IPT_MATCH_ITERATE(e, check_match, name, &e->ip, e->comefrom);
+ j = 0;
+ ret = IPT_MATCH_ITERATE(e, check_match, name, &e->ip, e->comefrom, &j);
if (ret)
- return ret;
+ goto cleanup_matches;
- return check_target(e, name);
+ ret = check_target(e, name);
+ if (ret)
+ goto cleanup_matches;
+
+ (*i)++;
+ return 0;
+
+ cleanup_matches:
+ IPT_MATCH_ITERATE(e, cleanup_match, &j);
+ return ret;
}
static int
@@ -1673,10 +1711,17 @@
if (!mark_source_chains(newinfo, valid_hooks, entry1))
goto free_newinfo;
+ i = 0;
ret = IPT_ENTRY_ITERATE(entry1, newinfo->size, compat_check_entry,
- name);
- if (ret)
- goto free_newinfo;
+ name, &i);
+ if (ret) {
+ j -= i;
+ IPT_ENTRY_ITERATE_CONTINUE(entry1, newinfo->size, i,
+ compat_release_entry, &j);
+ IPT_ENTRY_ITERATE(entry1, newinfo->size, cleanup_entry, &i);
+ xt_free_table_info(newinfo);
+ return ret;
+ }
/* And one copy for every other CPU */
for_each_possible_cpu(i)
@@ -1691,7 +1736,7 @@
free_newinfo:
xt_free_table_info(newinfo);
out:
- IPT_ENTRY_ITERATE(entry0, total_size, cleanup_entry, &j);
+ IPT_ENTRY_ITERATE(entry0, total_size, compat_release_entry, &j);
return ret;
out_unlock:
compat_flush_offsets();