iptables: ensure number of counters is >0 in do_replace()

After improving setsockopt() coverage in trinity, I started triggering
vmalloc failures pretty reliably from this code path:

warn_alloc_failed+0xe9/0x140
__vmalloc_node_range+0x1be/0x270
vzalloc+0x4b/0x50
__do_replace+0x52/0x260 [ip_tables]
do_ipt_set_ctl+0x15d/0x1d0 [ip_tables]
nf_setsockopt+0x65/0x90
ip_setsockopt+0x61/0xa0
raw_setsockopt+0x16/0x60
sock_common_setsockopt+0x14/0x20
SyS_setsockopt+0x71/0xd0

It turns out we don't validate that the num_counters field in the
struct we pass in from userspace is initialized.

Signed-off-by: Dave Jones <redacted>

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index c69db7fa25ee..12a33d178614 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c

@@ -1262,6 +1262,9 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
 	/* overflow check */
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

Dave Jones [off-list ref] wrote:

Good catch.  Due to iptables wonderful copy-paste programming model,
this also needs fixing in compat_do_replace, ip6tables, arbtables and
ebtables (8 different places, ick).

On Wed, May 20, 2015 at 01:19:50AM +0200, Florian Westphal wrote:
 > Dave Jones [off-list ref] wrote:
 > > After improving setsockopt() coverage in trinity, I started triggering
 > > vmalloc failures pretty reliably from this code path:
 > > 
 > > warn_alloc_failed+0xe9/0x140
 > > __vmalloc_node_range+0x1be/0x270
 > > vzalloc+0x4b/0x50
 > > __do_replace+0x52/0x260 [ip_tables]
 > > do_ipt_set_ctl+0x15d/0x1d0 [ip_tables]
 > > nf_setsockopt+0x65/0x90
 > > ip_setsockopt+0x61/0xa0
 > > raw_setsockopt+0x16/0x60
 > > sock_common_setsockopt+0x14/0x20
 > > SyS_setsockopt+0x71/0xd0
 > > 
 > > It turns out we don't validate that the num_counters field in the
 > > struct we pass in from userspace is initialized.
 > > 
 > > Signed-off-by: Dave Jones [off-list ref]
 > > 
 > > diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
 > > index c69db7fa25ee..12a33d178614 100644
 > > --- a/net/ipv4/netfilter/ip_tables.c
 > > +++ b/net/ipv4/netfilter/ip_tables.c
 > > @@ -1262,6 +1262,9 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
 > >  	/* overflow check */
 > >  	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 > >  		return -ENOMEM;
 > > +	if (tmp.num_counters == 0)
 > > +		return -EINVAL;
 > > +
 > 
 > Good catch.  Due to iptables wonderful copy-paste programming model,
 > this also needs fixing in compat_do_replace, ip6tables, arbtables and
 > ebtables (8 different places, ick).

ugh. ok, I'll fix them all up.
What's the preferred format, 8 separate patches, or 1 all-in-one diff
for all instances of this bug ?

thanks,

	Dave

From: Dave Jones <redacted>
Date: Tue, 19 May 2015 19:42:52 -0400

What's the preferred format, 8 separate patches, or 1 all-in-one
diff for all instances of this bug ?

Personally, I think you could do this in one patch.

After improving setsockopt() coverage in trinity, I started triggering
vmalloc failures pretty reliably from this code path:

warn_alloc_failed+0xe9/0x140
__vmalloc_node_range+0x1be/0x270
vzalloc+0x4b/0x50
__do_replace+0x52/0x260 [ip_tables]
do_ipt_set_ctl+0x15d/0x1d0 [ip_tables]
nf_setsockopt+0x65/0x90
ip_setsockopt+0x61/0xa0
raw_setsockopt+0x16/0x60
sock_common_setsockopt+0x14/0x20
SyS_setsockopt+0x71/0xd0

It turns out we don't validate that the num_counters field in the
struct we pass in from userspace is initialized.

The same problem also exists in ebtables, arptables, ipv6, and the
compat variants.

Signed-off-by: Dave Jones <redacted>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 91180a7fc943..24c7c96bf5f8 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c

@@ -1117,6 +1117,8 @@ static int do_replace(struct net *net, const void __user *user,
 		return -ENOMEM;
 	if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
 
 	tmp.name[sizeof(tmp.name) - 1] = 0;
 

@@ -2159,6 +2161,8 @@ static int compat_copy_ebt_replace_from_user(struct ebt_replace *repl,
 		return -ENOMEM;
 	if (tmp.num_counters >= INT_MAX / sizeof(struct ebt_counter))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
 
 	memcpy(repl, &tmp, offsetof(struct ebt_replace, hook_entry));
 

diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 13bfe84bf3ca..a61200754f4b 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c

@@ -1075,6 +1075,9 @@ static int do_replace(struct net *net, const void __user *user,
 	/* overflow check */
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

@@ -1499,6 +1502,9 @@ static int compat_do_replace(struct net *net, void __user *user,
 		return -ENOMEM;
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index c69db7fa25ee..2d0e265fef6e 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c

@@ -1262,6 +1262,9 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
 	/* overflow check */
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

@@ -1809,6 +1812,9 @@ compat_do_replace(struct net *net, void __user *user, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 1a732a1d3c8e..62f5b0d0bc9b 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c

@@ -1275,6 +1275,9 @@ do_replace(struct net *net, const void __user *user, unsigned int len)
 	/* overflow check */
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

@@ -1822,6 +1825,9 @@ compat_do_replace(struct net *net, void __user *user, unsigned int len)
 		return -ENOMEM;
 	if (tmp.num_counters >= INT_MAX / sizeof(struct xt_counters))
 		return -ENOMEM;
+	if (tmp.num_counters == 0)
+		return -EINVAL;
+
 	tmp.name[sizeof(tmp.name)-1] = 0;
 
 	newinfo = xt_alloc_table_info(tmp.size);

On Tue, May 19, 2015 at 08:55:17PM -0400, Dave Jones wrote:

After improving setsockopt() coverage in trinity, I started triggering
vmalloc failures pretty reliably from this code path:

warn_alloc_failed+0xe9/0x140
__vmalloc_node_range+0x1be/0x270
vzalloc+0x4b/0x50
__do_replace+0x52/0x260 [ip_tables]
do_ipt_set_ctl+0x15d/0x1d0 [ip_tables]
nf_setsockopt+0x65/0x90
ip_setsockopt+0x61/0xa0
raw_setsockopt+0x16/0x60
sock_common_setsockopt+0x14/0x20
SyS_setsockopt+0x71/0xd0

It turns out we don't validate that the num_counters field in the
struct we pass in from userspace is initialized.

The same problem also exists in ebtables, arptables, ipv6, and the
compat variants.

Applied.

This also applies to -stable kernels:

3.2.x
3.4.x
3.10.x
3.12.x
3.14.x
3.18.x
4.0.x

so after some testing and a little while, I'll pass this on.

Thanks.