From bdf533de6968e9686df777dc178486f600c6e617 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 22 Mar 2016 18:02:49 +0100
Subject: [PATCH] netfilter: x_tables: validate e->target_offset early
We should check that e->target_offset is sane before
mark_source_chains gets called since it will fetch the target entry
for loop detection.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/ipv4/netfilter/arp_tables.c | 17 ++++++++---------
net/ipv4/netfilter/ip_tables.c | 17 ++++++++---------
net/ipv6/netfilter/ip6_tables.c | 17 ++++++++---------
3 files changed, 24 insertions(+), 27 deletions(-)
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index bf08192..830bbe8 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -474,14 +474,12 @@ next:
return 1;
}
-static inline int check_entry(const struct arpt_entry *e, const char *name)
+static inline int check_entry(const struct arpt_entry *e)
{
const struct xt_entry_target *t;
- if (!arp_checkentry(&e->arp)) {
- duprintf("arp_tables: arp check failed %p %s.\n", e, name);
+ if (!arp_checkentry(&e->arp))
return -EINVAL;
- }
if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset)
return -EINVAL;
@@ -522,10 +520,6 @@ find_check_entry(struct arpt_entry *e, const char *name, unsigned int size)
struct xt_target *target;
int ret;
- ret = check_entry(e, name);
- if (ret)
- return ret;
-
e->counters.pcnt = xt_percpu_counter_alloc();
if (IS_ERR_VALUE(e->counters.pcnt))
return -ENOMEM;
@@ -576,6 +570,7 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
unsigned int valid_hooks)
{
unsigned int h;
+ int err;
if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
(unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
@@ -590,6 +585,10 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
return -EINVAL;
}
+ err = check_entry(e);
+ if (err)
+ return err;
+
/* Check hooks & underflows */
for (h = 0; h < NF_ARP_NUMHOOKS; h++) {
if (!(valid_hooks & (1 << h)))
@@ -1246,7 +1245,7 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
}
/* For purposes of check_entry casting the compat entry is fine */
- ret = check_entry((struct arpt_entry *)e, name);
+ ret = check_entry((struct arpt_entry *)e);
if (ret)
return ret;
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index e53f8d6..1d72a3c 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -569,14 +569,12 @@ static void cleanup_match(struct xt_entry_match *m, struct net *net)
}
static int
-check_entry(const struct ipt_entry *e, const char *name)
+check_entry(const struct ipt_entry *e)
{
const struct xt_entry_target *t;
- if (!ip_checkentry(&e->ip)) {
- duprintf("ip check failed %p %s.\n", e, name);
+ if (!ip_checkentry(&e->ip))
return -EINVAL;
- }
if (e->target_offset + sizeof(struct xt_entry_target) >
e->next_offset)
@@ -666,10 +664,6 @@ find_check_entry(struct ipt_entry *e, struct net *net, const char *name,
struct xt_mtchk_param mtpar;
struct xt_entry_match *ematch;
- ret = check_entry(e, name);
- if (ret)
- return ret;
-
e->counters.pcnt = xt_percpu_counter_alloc();
if (IS_ERR_VALUE(e->counters.pcnt))
return -ENOMEM;
@@ -741,6 +735,7 @@ check_entry_size_and_hooks(struct ipt_entry *e,
unsigned int valid_hooks)
{
unsigned int h;
+ int err;
if ((unsigned long)e % __alignof__(struct ipt_entry) != 0 ||
(unsigned char *)e + sizeof(struct ipt_entry) >= limit) {
@@ -755,6 +750,10 @@ check_entry_size_and_hooks(struct ipt_entry *e,
return -EINVAL;
}
+ err = check_entry(e);
+ if (err)
+ return err;
+
/* Check hooks & underflows */
for (h = 0; h < NF_INET_NUMHOOKS; h++) {
if (!(valid_hooks & (1 << h)))
@@ -1506,7 +1505,7 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
}
/* For purposes of check_entry casting the compat entry is fine */
- ret = check_entry((struct ipt_entry *)e, name);
+ ret = check_entry((struct ipt_entry *)e);
if (ret)
return ret;
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 84f9baf..26a5ad1 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -581,14 +581,12 @@ static void cleanup_match(struct xt_entry_match *m, struct net *net)
}
static int
-check_entry(const struct ip6t_entry *e, const char *name)
+check_entry(const struct ip6t_entry *e)
{
const struct xt_entry_target *t;
- if (!ip6_checkentry(&e->ipv6)) {
- duprintf("ip_tables: ip check failed %p %s.\n", e, name);
+ if (!ip6_checkentry(&e->ipv6))
return -EINVAL;
- }
if (e->target_offset + sizeof(struct xt_entry_target) >
e->next_offset)
@@ -679,10 +677,6 @@ find_check_entry(struct ip6t_entry *e, struct net *net, const char *name,
struct xt_mtchk_param mtpar;
struct xt_entry_match *ematch;
- ret = check_entry(e, name);
- if (ret)
- return ret;
-
e->counters.pcnt = xt_percpu_counter_alloc();
if (IS_ERR_VALUE(e->counters.pcnt))
return -ENOMEM;
@@ -753,6 +747,7 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
unsigned int valid_hooks)
{
unsigned int h;
+ int err;
if ((unsigned long)e % __alignof__(struct ip6t_entry) != 0 ||
(unsigned char *)e + sizeof(struct ip6t_entry) >= limit) {
@@ -767,6 +762,10 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
return -EINVAL;
}
+ err = check_entry(e);
+ if (err)
+ return err;
+
/* Check hooks & underflows */
for (h = 0; h < NF_INET_NUMHOOKS; h++) {
if (!(valid_hooks & (1 << h)))
@@ -1518,7 +1517,7 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
}
/* For purposes of check_entry casting the compat entry is fine */
- ret = check_entry((struct ip6t_entry *)e, name);
+ ret = check_entry((struct ip6t_entry *)e);
if (ret)
return ret;
--
2.7.4
From 6e94e0cfb0887e4013b3b930fa6ab1fe6bb6ba91 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 22 Mar 2016 18:02:50 +0100
Subject: [PATCH] netfilter: x_tables: make sure e->next_offset covers
remaining blob size
Otherwise this function may read data beyond the ruleset blob.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/ipv4/netfilter/arp_tables.c | 6 ++++--
net/ipv4/netfilter/ip_tables.c | 6 ++++--
net/ipv6/netfilter/ip6_tables.c | 6 ++++--
3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 830bbe8..51d4fe5 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -573,7 +573,8 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
int err;
if ((unsigned long)e % __alignof__(struct arpt_entry) != 0 ||
- (unsigned char *)e + sizeof(struct arpt_entry) >= limit) {
+ (unsigned char *)e + sizeof(struct arpt_entry) >= limit ||
+ (unsigned char *)e + e->next_offset > limit) {
duprintf("Bad offset %p\n", e);
return -EINVAL;
}
@@ -1232,7 +1233,8 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
duprintf("check_compat_entry_size_and_hooks %p\n", e);
if ((unsigned long)e % __alignof__(struct compat_arpt_entry) != 0 ||
- (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit) {
+ (unsigned char *)e + sizeof(struct compat_arpt_entry) >= limit ||
+ (unsigned char *)e + e->next_offset > limit) {
duprintf("Bad offset %p, limit = %p\n", e, limit);
return -EINVAL;
}
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 1d72a3c..fb7694e 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -738,7 +738,8 @@ check_entry_size_and_hooks(struct ipt_entry *e,
int err;
if ((unsigned long)e % __alignof__(struct ipt_entry) != 0 ||
- (unsigned char *)e + sizeof(struct ipt_entry) >= limit) {
+ (unsigned char *)e + sizeof(struct ipt_entry) >= limit ||
+ (unsigned char *)e + e->next_offset > limit) {
duprintf("Bad offset %p\n", e);
return -EINVAL;
}
@@ -1492,7 +1493,8 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
duprintf("check_compat_entry_size_and_hooks %p\n", e);
if ((unsigned long)e % __alignof__(struct compat_ipt_entry) != 0 ||
- (unsigned char *)e + sizeof(struct compat_ipt_entry) >= limit) {
+ (unsigned char *)e + sizeof(struct compat_ipt_entry) >= limit ||
+ (unsigned char *)e + e->next_offset > limit) {
duprintf("Bad offset %p, limit = %p\n", e, limit);
return -EINVAL;
}
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 26a5ad1..b248528f 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -750,7 +750,8 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
int err;
if ((unsigned long)e % __alignof__(struct ip6t_entry) != 0 ||
- (unsigned char *)e + sizeof(struct ip6t_entry) >= limit) {
+ (unsigned char *)e + sizeof(struct ip6t_entry) >= limit ||
+ (unsigned char *)e + e->next_offset > limit) {
duprintf("Bad offset %p\n", e);
return -EINVAL;
}
@@ -1504,7 +1505,8 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
duprintf("check_compat_entry_size_and_hooks %p\n", e);
if ((unsigned long)e % __alignof__(struct compat_ip6t_entry) != 0 ||
- (unsigned char *)e + sizeof(struct compat_ip6t_entry) >= limit) {
+ (unsigned char *)e + sizeof(struct compat_ip6t_entry) >= limit ||
+ (unsigned char *)e + e->next_offset > limit) {
duprintf("Bad offset %p, limit = %p\n", e, limit);
return -EINVAL;
}
--
2.7.4
From 54d83fc74aa9ec72794373cb47432c5f7fb1a309 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Tue, 22 Mar 2016 18:02:52 +0100
Subject: [PATCH] netfilter: x_tables: fix unconditional helper
Ben Hawkes says:
In the mark_source_chains function (net/ipv4/netfilter/ip_tables.c) it
is possible for a user-supplied ipt_entry structure to have a large
next_offset field. This field is not bounds checked prior to writing a
counter value at the supplied offset.
Problem is that mark_source_chains should not have been called --
the rule doesn't have a next entry, so its supposed to return
an absolute verdict of either ACCEPT or DROP.
However, the function conditional() doesn't work as the name implies.
It only checks that the rule is using wildcard address matching.
However, an unconditional rule must also not be using any matches
(no -m args).
The underflow validator only checked the addresses, therefore
passing the 'unconditional absolute verdict' test, while
mark_source_chains also tested for presence of matches, and thus
proceeeded to the next (not-existent) rule.
Unify this so that all the callers have same idea of 'unconditional rule'.
Reported-by: Ben Hawkes <hawkes@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
net/ipv4/netfilter/arp_tables.c | 18 +++++++++---------
net/ipv4/netfilter/ip_tables.c | 23 +++++++++++------------
net/ipv6/netfilter/ip6_tables.c | 23 +++++++++++------------
3 files changed, 31 insertions(+), 33 deletions(-)
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 51d4fe5..a1bb5e7 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -359,11 +359,12 @@ unsigned int arpt_do_table(struct sk_buff *skb,
}
/* All zeroes == unconditional rule. */
-static inline bool unconditional(const struct arpt_arp *arp)
+static inline bool unconditional(const struct arpt_entry *e)
{
static const struct arpt_arp uncond;
- return memcmp(arp, &uncond, sizeof(uncond)) == 0;
+ return e->target_offset == sizeof(struct arpt_entry) &&
+ memcmp(&e->arp, &uncond, sizeof(uncond)) == 0;
}
/* Figures out from what hook each rule can be called: returns 0 if
@@ -402,11 +403,10 @@ static int mark_source_chains(const struct xt_table_info *newinfo,
|= ((1 << hook) | (1 << NF_ARP_NUMHOOKS));
/* Unconditional return/END. */
- if ((e->target_offset == sizeof(struct arpt_entry) &&
+ if ((unconditional(e) &&
(strcmp(t->target.u.user.name,
XT_STANDARD_TARGET) == 0) &&
- t->verdict < 0 && unconditional(&e->arp)) ||
- visited) {
+ t->verdict < 0) || visited) {
unsigned int oldpos, size;
if ((strcmp(t->target.u.user.name,
@@ -551,7 +551,7 @@ static bool check_underflow(const struct arpt_entry *e)
const struct xt_entry_target *t;
unsigned int verdict;
- if (!unconditional(&e->arp))
+ if (!unconditional(e))
return false;
t = arpt_get_target_c(e);
if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
@@ -598,9 +598,9 @@ static inline int check_entry_size_and_hooks(struct arpt_entry *e,
newinfo->hook_entry[h] = hook_entries[h];
if ((unsigned char *)e - base == underflows[h]) {
if (!check_underflow(e)) {
- pr_err("Underflows must be unconditional and "
- "use the STANDARD target with "
- "ACCEPT/DROP\n");
+ pr_debug("Underflows must be unconditional and "
+ "use the STANDARD target with "
+ "ACCEPT/DROP\n");
return -EINVAL;
}
newinfo->underflow[h] = underflows[h];
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index fb7694e..89b5d95 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -168,11 +168,12 @@ get_entry(const void *base, unsigned int offset)
/* All zeroes == unconditional rule. */
/* Mildly perf critical (only if packet tracing is on) */
-static inline bool unconditional(const struct ipt_ip *ip)
+static inline bool unconditional(const struct ipt_entry *e)
{
static const struct ipt_ip uncond;
- return memcmp(ip, &uncond, sizeof(uncond)) == 0;
+ return e->target_offset == sizeof(struct ipt_entry) &&
+ memcmp(&e->ip, &uncond, sizeof(uncond)) == 0;
#undef FWINV
}
@@ -229,11 +230,10 @@ get_chainname_rulenum(const struct ipt_entry *s, const struct ipt_entry *e,
} else if (s == e) {
(*rulenum)++;
- if (s->target_offset == sizeof(struct ipt_entry) &&
+ if (unconditional(s) &&
strcmp(t->target.u.kernel.target->name,
XT_STANDARD_TARGET) == 0 &&
- t->verdict < 0 &&
- unconditional(&s->ip)) {
+ t->verdict < 0) {
/* Tail of chains: STANDARD target (return/policy) */
*comment = *chainname == hookname
? comments[NF_IP_TRACE_COMMENT_POLICY]
@@ -476,11 +476,10 @@ mark_source_chains(const struct xt_table_info *newinfo,
e->comefrom |= ((1 << hook) | (1 << NF_INET_NUMHOOKS));
/* Unconditional return/END. */
- if ((e->target_offset == sizeof(struct ipt_entry) &&
+ if ((unconditional(e) &&
(strcmp(t->target.u.user.name,
XT_STANDARD_TARGET) == 0) &&
- t->verdict < 0 && unconditional(&e->ip)) ||
- visited) {
+ t->verdict < 0) || visited) {
unsigned int oldpos, size;
if ((strcmp(t->target.u.user.name,
@@ -715,7 +714,7 @@ static bool check_underflow(const struct ipt_entry *e)
const struct xt_entry_target *t;
unsigned int verdict;
- if (!unconditional(&e->ip))
+ if (!unconditional(e))
return false;
t = ipt_get_target_c(e);
if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
@@ -763,9 +762,9 @@ check_entry_size_and_hooks(struct ipt_entry *e,
newinfo->hook_entry[h] = hook_entries[h];
if ((unsigned char *)e - base == underflows[h]) {
if (!check_underflow(e)) {
- pr_err("Underflows must be unconditional and "
- "use the STANDARD target with "
- "ACCEPT/DROP\n");
+ pr_debug("Underflows must be unconditional and "
+ "use the STANDARD target with "
+ "ACCEPT/DROP\n");
return -EINVAL;
}
newinfo->underflow[h] = underflows[h];
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index b248528f..541b59f 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -198,11 +198,12 @@ get_entry(const void *base, unsigned int offset)
/* All zeroes == unconditional rule. */
/* Mildly perf critical (only if packet tracing is on) */
-static inline bool unconditional(const struct ip6t_ip6 *ipv6)
+static inline bool unconditional(const struct ip6t_entry *e)
{
static const struct ip6t_ip6 uncond;
- return memcmp(ipv6, &uncond, sizeof(uncond)) == 0;
+ return e->target_offset == sizeof(struct ip6t_entry) &&
+ memcmp(&e->ipv6, &uncond, sizeof(uncond)) == 0;
}
static inline const struct xt_entry_target *
@@ -258,11 +259,10 @@ get_chainname_rulenum(const struct ip6t_entry *s, const struct ip6t_entry *e,
} else if (s == e) {
(*rulenum)++;
- if (s->target_offset == sizeof(struct ip6t_entry) &&
+ if (unconditional(s) &&
strcmp(t->target.u.kernel.target->name,
XT_STANDARD_TARGET) == 0 &&
- t->verdict < 0 &&
- unconditional(&s->ipv6)) {
+ t->verdict < 0) {
/* Tail of chains: STANDARD target (return/policy) */
*comment = *chainname == hookname
? comments[NF_IP6_TRACE_COMMENT_POLICY]
@@ -488,11 +488,10 @@ mark_source_chains(const struct xt_table_info *newinfo,
e->comefrom |= ((1 << hook) | (1 << NF_INET_NUMHOOKS));
/* Unconditional return/END. */
- if ((e->target_offset == sizeof(struct ip6t_entry) &&
+ if ((unconditional(e) &&
(strcmp(t->target.u.user.name,
XT_STANDARD_TARGET) == 0) &&
- t->verdict < 0 &&
- unconditional(&e->ipv6)) || visited) {
+ t->verdict < 0) || visited) {
unsigned int oldpos, size;
if ((strcmp(t->target.u.user.name,
@@ -727,7 +726,7 @@ static bool check_underflow(const struct ip6t_entry *e)
const struct xt_entry_target *t;
unsigned int verdict;
- if (!unconditional(&e->ipv6))
+ if (!unconditional(e))
return false;
t = ip6t_get_target_c(e);
if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
@@ -775,9 +774,9 @@ check_entry_size_and_hooks(struct ip6t_entry *e,
newinfo->hook_entry[h] = hook_entries[h];
if ((unsigned char *)e - base == underflows[h]) {
if (!check_underflow(e)) {
- pr_err("Underflows must be unconditional and "
- "use the STANDARD target with "
- "ACCEPT/DROP\n");
+ pr_debug("Underflows must be unconditional and "
+ "use the STANDARD target with "
+ "ACCEPT/DROP\n");
return -EINVAL;
}
newinfo->underflow[h] = underflows[h];
--
2.7.4