From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Westphal Subject: [PATCH -stable 3.12.y] netfilter: x_tables: speed up jump target validation Date: Mon, 1 Aug 2016 20:38:20 +0200 Message-ID: <1470076704-13325-2-git-send-email-fw@strlen.de> References: <1470076704-13325-1-git-send-email-fw@strlen.de> Cc: netfilter-devel@vger.kernel.org, stable@kernel.org, alexander.levin@verizon.com, Florian Westphal To: pablo@netfilter.org Return-path: Received: from Chamillionaire.breakpoint.cc ([146.0.238.67]:46540 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754741AbcHATTM (ORCPT ); Mon, 1 Aug 2016 15:19:12 -0400 In-Reply-To: <1470076704-13325-1-git-send-email-fw@strlen.de> Sender: netfilter-devel-owner@vger.kernel.org List-ID: [ Upstream commit f4dc77713f8016d2e8a3295e1c9c53a21f296def ] The dummy ruleset I used to test the original validation change was broken, most rules were unreachable and were not tested by mark_source_chains(). In some cases rulesets that used to load in a few seconds now require several minutes. sample ruleset that shows the behaviour: echo "*filter" for i in $(seq 0 100000);do printf ":chain_%06x - [0:0]\n" $i done for i in $(seq 0 100000);do printf -- "-A INPUT -j chain_%06x\n" $i printf -- "-A INPUT -j chain_%06x\n" $i printf -- "-A INPUT -j chain_%06x\n" $i done echo COMMIT [ pipe result into iptables-restore ] This ruleset will be about 74mbyte in size, with ~500k searches though all 500k[1] rule entries. iptables-restore will take forever (gave up after 10 minutes) Instead of always searching the entire blob for a match, fill an array with the start offsets of every single ipt_entry struct, then do a binary search to check if the jump target is present or not. After this change ruleset restore times get again close to what one gets when reverting 36472341017529e (~3 seconds on my workstation). [1] every user-defined rule gets an implicit RETURN, so we get 300k jumps + 100k userchains + 100k returns -> 500k rule entries Fixes: 36472341017529e ("netfilter: x_tables: validate targets of jumps") Reported-by: Jeff Wu Tested-by: Jeff Wu Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/x_tables.h | 4 +++ net/ipv4/netfilter/arp_tables.c | 39 ++++++++++++++++++++++------- net/ipv4/netfilter/ip_tables.c | 34 ++++++++++++++++++++------ net/ipv6/netfilter/ip6_tables.c | 33 +++++++++++++++++++------ net/netfilter/x_tables.c | 50 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 137 insertions(+), 23 deletions(-) diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 1d24aa7..07d6b44 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -243,6 +243,10 @@ int xt_check_entry_offsets(const void *base, const char *elems, unsigned int target_offset, unsigned int next_offset); +unsigned int *xt_alloc_entry_offsets(unsigned int size); +bool xt_find_jump_offset(const unsigned int *offsets, + unsigned int target, unsigned int size); + extern int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto, bool inv_proto); extern int xt_check_target(struct xt_tgchk_param *, diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 95a5f26..83e276a 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -362,7 +362,8 @@ static inline bool unconditional(const struct arpt_entry *e) * there are loops. Puts hook bitmask in comefrom. */ static int mark_source_chains(const struct xt_table_info *newinfo, - unsigned int valid_hooks, void *entry0) + unsigned int valid_hooks, void *entry0, + unsigned int *offsets) { unsigned int hook; @@ -451,6 +452,11 @@ static int mark_source_chains(const struct xt_table_info *newinfo, /* This a jump; chase it. */ duprintf("Jump rule %u -> %u\n", pos, newpos); + if (!xt_find_jump_offset(offsets, newpos, + newinfo->number)) + return 0; + e = (struct arpt_entry *) + (entry0 + newpos); } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; @@ -610,6 +616,7 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, const struct arpt_replace *repl) { struct arpt_entry *iter; + unsigned int *offsets; unsigned int i; int ret = 0; @@ -623,8 +630,12 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, } duprintf("translate_table: size %u\n", newinfo->size); - i = 0; + offsets = xt_alloc_entry_offsets(newinfo->number); + if (!offsets) + return -ENOMEM; + + i = 0; /* Walk through entries, checking offsets. */ xt_entry_foreach(iter, entry0, newinfo->size) { ret = check_entry_size_and_hooks(iter, newinfo, entry0, @@ -633,7 +644,9 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, repl->underflow, repl->valid_hooks); if (ret != 0) - break; + goto out_free; + if (i < repl->num_entries) + offsets[i] = (void *)iter - entry0; ++i; if (strcmp(arpt_get_target(iter)->u.user.name, XT_ERROR_TARGET) == 0) @@ -641,12 +654,13 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, } duprintf("translate_table: ARPT_ENTRY_ITERATE gives %d\n", ret); if (ret != 0) - return ret; + goto out_free; + ret = -EINVAL; if (i != repl->num_entries) { duprintf("translate_table: %u not %u entries\n", i, repl->num_entries); - return -EINVAL; + goto out_free; } /* Check hooks all assigned */ @@ -654,20 +668,24 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, /* Only hooks which are valid */ if (!(repl->valid_hooks & (1 << i))) continue; + if (newinfo->hook_entry[i] == 0xFFFFFFFF) { duprintf("Invalid hook entry %u %u\n", i, repl->hook_entry[i]); - return -EINVAL; + goto out_free; } if (newinfo->underflow[i] == 0xFFFFFFFF) { duprintf("Invalid underflow %u %u\n", i, repl->underflow[i]); - return -EINVAL; + goto out_free; } } - if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) - return -ELOOP; + if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) { + ret = -ELOOP; + goto out_free; + } + kvfree(offsets); /* Finally, each sanity check must pass */ i = 0; @@ -694,6 +712,9 @@ static int translate_table(struct xt_table_info *newinfo, void *entry0, } return ret; + out_free: + kvfree(offsets); + return ret; } static void get_counters(const struct xt_table_info *t, diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index 92c8f27..1657cc1 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -438,7 +438,8 @@ ipt_do_table(struct sk_buff *skb, there are loops. Puts hook bitmask in comefrom. */ static int mark_source_chains(const struct xt_table_info *newinfo, - unsigned int valid_hooks, void *entry0) + unsigned int valid_hooks, void *entry0, + unsigned int *offsets) { unsigned int hook; @@ -531,6 +532,11 @@ mark_source_chains(const struct xt_table_info *newinfo, /* This a jump; chase it. */ duprintf("Jump rule %u -> %u\n", pos, newpos); + if (!xt_find_jump_offset(offsets, newpos, + newinfo->number)) + return 0; + e = (struct ipt_entry *) + (entry0 + newpos); } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; @@ -777,6 +783,7 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, const struct ipt_replace *repl) { struct ipt_entry *iter; + unsigned int *offsets; unsigned int i; int ret = 0; @@ -790,6 +797,10 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, } duprintf("translate_table: size %u\n", newinfo->size); + + offsets = xt_alloc_entry_offsets(newinfo->number); + if (!offsets) + return -ENOMEM; i = 0; /* Walk through entries, checking offsets. */ xt_entry_foreach(iter, entry0, newinfo->size) { @@ -799,17 +810,20 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, repl->underflow, repl->valid_hooks); if (ret != 0) - return ret; + goto out_free; + if (i < repl->num_entries) + offsets[i] = (void *)iter - entry0; ++i; if (strcmp(ipt_get_target(iter)->u.user.name, XT_ERROR_TARGET) == 0) ++newinfo->stacksize; } + ret = -EINVAL; if (i != repl->num_entries) { duprintf("translate_table: %u not %u entries\n", i, repl->num_entries); - return -EINVAL; + goto out_free; } /* Check hooks all assigned */ @@ -820,17 +834,20 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, if (newinfo->hook_entry[i] == 0xFFFFFFFF) { duprintf("Invalid hook entry %u %u\n", i, repl->hook_entry[i]); - return -EINVAL; + goto out_free; } if (newinfo->underflow[i] == 0xFFFFFFFF) { duprintf("Invalid underflow %u %u\n", i, repl->underflow[i]); - return -EINVAL; + goto out_free; } } - if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) - return -ELOOP; + if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) { + ret = -ELOOP; + goto out_free; + } + kvfree(offsets); /* Finally, each sanity check must pass */ i = 0; @@ -857,6 +874,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, } return ret; + out_free: + kvfree(offsets); + return ret; } static void diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index e214222..d24ff5d 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -448,7 +448,8 @@ ip6t_do_table(struct sk_buff *skb, there are loops. Puts hook bitmask in comefrom. */ static int mark_source_chains(const struct xt_table_info *newinfo, - unsigned int valid_hooks, void *entry0) + unsigned int valid_hooks, void *entry0, + unsigned int *offsets) { unsigned int hook; @@ -541,6 +542,11 @@ mark_source_chains(const struct xt_table_info *newinfo, /* This a jump; chase it. */ duprintf("Jump rule %u -> %u\n", pos, newpos); + if (!xt_find_jump_offset(offsets, newpos, + newinfo->number)) + return 0; + e = (struct ip6t_entry *) + (entry0 + newpos); } else { /* ... this is a fallthru */ newpos = pos + e->next_offset; @@ -787,6 +793,7 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, const struct ip6t_replace *repl) { struct ip6t_entry *iter; + unsigned int *offsets; unsigned int i; int ret = 0; @@ -800,6 +807,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, } duprintf("translate_table: size %u\n", newinfo->size); + offsets = xt_alloc_entry_offsets(newinfo->number); + if (!offsets) + return -ENOMEM; i = 0; /* Walk through entries, checking offsets. */ xt_entry_foreach(iter, entry0, newinfo->size) { @@ -809,17 +819,20 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, repl->underflow, repl->valid_hooks); if (ret != 0) - return ret; + goto out_free; + if (i < repl->num_entries) + offsets[i] = (void *)iter - entry0; ++i; if (strcmp(ip6t_get_target(iter)->u.user.name, XT_ERROR_TARGET) == 0) ++newinfo->stacksize; } + ret = -EINVAL; if (i != repl->num_entries) { duprintf("translate_table: %u not %u entries\n", i, repl->num_entries); - return -EINVAL; + goto out_free; } /* Check hooks all assigned */ @@ -830,17 +843,20 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, if (newinfo->hook_entry[i] == 0xFFFFFFFF) { duprintf("Invalid hook entry %u %u\n", i, repl->hook_entry[i]); - return -EINVAL; + goto out_free; } if (newinfo->underflow[i] == 0xFFFFFFFF) { duprintf("Invalid underflow %u %u\n", i, repl->underflow[i]); - return -EINVAL; + goto out_free; } } - if (!mark_source_chains(newinfo, repl->valid_hooks, entry0)) - return -ELOOP; + if (!mark_source_chains(newinfo, repl->valid_hooks, entry0, offsets)) { + ret = -ELOOP; + goto out_free; + } + kvfree(offsets); /* Finally, each sanity check must pass */ i = 0; @@ -867,6 +883,9 @@ translate_table(struct net *net, struct xt_table_info *newinfo, void *entry0, } return ret; + out_free: + kvfree(offsets); + return ret; } static void diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 51c141b..94ce5ff 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -721,6 +721,56 @@ int xt_check_entry_offsets(const void *base, } EXPORT_SYMBOL(xt_check_entry_offsets); +/** + * xt_alloc_entry_offsets - allocate array to store rule head offsets + * + * @size: number of entries + * + * Return: NULL or kmalloc'd or vmalloc'd array + */ +unsigned int *xt_alloc_entry_offsets(unsigned int size) +{ + unsigned int *off; + + off = kcalloc(size, sizeof(unsigned int), GFP_KERNEL | __GFP_NOWARN); + + if (off) + return off; + + if (size < (SIZE_MAX / sizeof(unsigned int))) + off = vmalloc(size * sizeof(unsigned int)); + + return off; +} +EXPORT_SYMBOL(xt_alloc_entry_offsets); + +/** + * xt_find_jump_offset - check if target is a valid jump offset + * + * @offsets: array containing all valid rule start offsets of a rule blob + * @target: the jump target to search for + * @size: entries in @offset + */ +bool xt_find_jump_offset(const unsigned int *offsets, + unsigned int target, unsigned int size) +{ + int m, low = 0, hi = size; + + while (hi > low) { + m = (low + hi) / 2u; + + if (offsets[m] > target) + hi = m; + else if (offsets[m] < target) + low = m + 1; + else + return true; + } + + return false; +} +EXPORT_SYMBOL(xt_find_jump_offset); + int xt_check_target(struct xt_tgchk_param *par, unsigned int size, u_int8_t proto, bool inv_proto) { -- 2.7.3