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[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>
This commit is contained in:
Dmitry Mishin 2007-06-05 12:56:09 -07:00 committed by David S. Miller
parent 3c158f7f57
commit 4c1b52bc7a
2 changed files with 83 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
include/linux/netfilter_ipv4/ip_tables.h
View File

@ -264,6 +264,26 @@ ipt_get_target(struct ipt_entry *e)
__ret; \
})
/* fn returns 0 to continue iteration */
#define IPT_ENTRY_ITERATE_CONTINUE(entries, size, n, fn, args...) \
({ \
unsigned int __i, __n; \
int __ret = 0; \
struct ipt_entry *__entry; \
\
for (__i = 0, __n = 0; __i < (size); \
__i += __entry->next_offset, __n++) { \
__entry = (void *)(entries) + __i; \
if (__n < n) \
continue; \
\
__ret = fn(__entry , ## args); \
if (__ret != 0) \
break; \
} \
__ret; \
})
/*
* Main firewall chains definitions and global var's definitions.
*/

81
net/ipv4/netfilter/ip_tables.c
View File

@ -499,7 +499,8 @@ check_entry(struct ipt_entry *e, const char *name)
}
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 @@ static inline int check_match(struct ipt_entry_match *m, const char *name,
m->u.kernel.match->name);
ret = -EINVAL;
}
if (!ret)
(*i)++;
return ret;
}
@ -537,11 +540,10 @@ find_check_match(struct ipt_entry_match *m,
}
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 @@ out:
}
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,
@ -1448,6 +1450,31 @@ compat_check_calc_match(struct ipt_entry_match *m,
return 0;
}
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,
@ -1485,10 +1512,10 @@ check_compat_entry_size_and_hooks(struct ipt_entry *e,
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 @@ check_compat_entry_size_and_hooks(struct ipt_entry *e,
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 @@ check_compat_entry_size_and_hooks(struct ipt_entry *e,
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 @@ static int compat_copy_entry_from_user(struct ipt_entry *e, void **dstptr,
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 @@ translate_compat_table(const char *name,
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 @@ translate_compat_table(const char *name,
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();