From 4c1b52bc7a2f5ee01ea3fc248a8748a1c6843f7c Mon Sep 17 00:00:00 2001 From: Dmitry Mishin Date: Tue, 5 Jun 2007 12:56:09 -0700 Subject: [PATCH] [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 Signed-off-by: Dmitry Mishin Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- include/linux/netfilter_ipv4/ip_tables.h | 20 ++++++ net/ipv4/netfilter/ip_tables.c | 81 ++++++++++++++++++------ 2 files changed, 83 insertions(+), 18 deletions(-) diff --git a/include/linux/netfilter_ipv4/ip_tables.h b/include/linux/netfilter_ipv4/ip_tables.h index 2f46dd728ee1..e992cd6b28f5 100644 --- a/include/linux/netfilter_ipv4/ip_tables.h +++ b/include/linux/netfilter_ipv4/ip_tables.h @@ -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. */ diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index e3f83bf160d9..9bacf1a03630 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -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; + + ret = check_target(e, name); + if (ret) + goto cleanup_matches; - return check_target(e, name); + (*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(); -- 2.20.1