* Bad behaviour when unintentionally mixing ipv4 and ipv6 addresses
@ 2011-05-25 15:59 Marcus Meissner
2011-06-02 4:03 ` David Miller
0 siblings, 1 reply; 6+ messages in thread
From: Marcus Meissner @ 2011-05-25 15:59 UTC (permalink / raw)
To: netdev; +Cc: max
[-- Attachment #1: Type: text/plain, Size: 1660 bytes --]
Hi,
By chance Reinhard Max spotted an interesting flaw in Linux bind(2)...
If you create a IPv4 socket and then incorrectly bind(2) to a IPv6 address
(which you got from getaddrinfo(3) or similar), the socket will be bound
to INADDR_ANY.
The reason is that the kernel just takes the sockaddr_in6 struct and
evaluates it as a sockaddr_in struct, with the port being OK, but the IPv4
sin_addr overlaying the IPv6 sin6_flowinfo field.
As the sin6_flowinfo field is usually 0, your service can end up listening
to the world.
A testprogram that you can strace is attached, run netstat -apn |grep 12345
afterwards to see it binds 0.0.0.0:12345.
Perhaps add a check like the one below? (untested)
Or use if (addr->sin_family == AF_INET6) to just catch the IPv6 case?
Ciao, Marcus
Subject: [PATCH] net/ipv4: Check for mistakenly passed in non-IPv4 address
Hi,
Check against mistakenly passing in IPv6 addresses (which would result
in an INADDR_ANY bind) or similar incompatible sockaddrs.
Ciao, Marcus
Signed-off-by: Marcus Meissner <meissner@suse.de>
Cc: Reinhard Max <max@suse.de>
---
net/ipv4/af_inet.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index cc14631..9c19260 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -465,6 +465,9 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
if (addr_len < sizeof(struct sockaddr_in))
goto out;
+ if (addr->sin_family != AF_INET)
+ goto out;
+
chk_addr_ret = inet_addr_type(sock_net(sk), addr->sin_addr.s_addr);
/* Not specified by any standard per-se, however it breaks too
--
1.7.4.1
[-- Attachment #2: xx.c --]
[-- Type: text/x-c++src, Size: 845 bytes --]
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char **argv) {
int fd,fd2;
struct sockaddr_in6 saddrin,saddrin2;
size_t len;
fd = socket(AF_INET,SOCK_STREAM,0);
if (fd == -1) {
perror("socket");
exit(1);
}
memset(&saddrin,0,sizeof(saddrin));
/*memcpy(&saddrin.sin6_addr, &in6addr_loopback, sizeof(saddrin.sin6_addr));*/
memset(&saddrin.sin6_addr, 0x42, sizeof(saddrin.sin6_addr));
saddrin.sin6_family = AF_INET6;
saddrin.sin6_port = htons(12345);
if (-1 == bind(fd, (struct sockaddr*)&saddrin, sizeof(saddrin))) {
perror("bind");
exit(1);
}
if (-1 == listen(fd, 5)) {
perror("listen");
exit(1);
}
len = sizeof(saddrin2);
fd2 = accept (fd, (struct sockaddr*)&saddrin2, &len);
if (fd2 == -1) perror("accept");
close(fd);
return 0;
}
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: Bad behaviour when unintentionally mixing ipv4 and ipv6 addresses
2011-05-25 15:59 Bad behaviour when unintentionally mixing ipv4 and ipv6 addresses Marcus Meissner
@ 2011-06-02 4:03 ` David Miller
2011-06-06 13:47 ` Reinhard Max
0 siblings, 1 reply; 6+ messages in thread
From: David Miller @ 2011-06-02 4:03 UTC (permalink / raw)
To: meissner; +Cc: netdev, max
From: Marcus Meissner <meissner@suse.de>
Date: Wed, 25 May 2011 17:59:18 +0200
> @@ -465,6 +465,9 @@ int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
> if (addr_len < sizeof(struct sockaddr_in))
> goto out;
>
> + if (addr->sin_family != AF_INET)
> + goto out;
> +
> chk_addr_ret = inet_addr_type(sock_net(sk), addr->sin_addr.s_addr);
Since we haven't been validating the sin_family field for 18+ years, the
chance to break some applications is very real.
But I think it's more important to fix this (and force any broken apps
to set sin_family correctly). So I will apply this, thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Bad behaviour when unintentionally mixing ipv4 and ipv6 addresses
2011-06-02 4:03 ` David Miller
@ 2011-06-06 13:47 ` Reinhard Max
2011-06-06 16:00 ` [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs Marcus Meissner
0 siblings, 1 reply; 6+ messages in thread
From: Reinhard Max @ 2011-06-06 13:47 UTC (permalink / raw)
To: David Miller; +Cc: meissner, netdev
On Wed, 1 Jun 2011 at 21:03, David Miller wrote:
> Since we haven't been validating the sin_family field for 18+ years,
> the chance to break some applications is very real.
>
> But I think it's more important to fix this (and force any broken
> apps to set sin_family correctly). So I will apply this, thanks.
I think a corresponding check should also go into inet6_bind() in
net/ipv6/af_inet6.c .
cu
Reinhard
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs
2011-06-06 13:47 ` Reinhard Max
@ 2011-06-06 16:00 ` Marcus Meissner
2011-06-06 21:48 ` David Miller
2011-06-07 7:25 ` Reinhard Max
0 siblings, 2 replies; 6+ messages in thread
From: Marcus Meissner @ 2011-06-06 16:00 UTC (permalink / raw)
To: Reinhard Max, David Miller, netdev
On Mon, Jun 06, 2011 at 03:47:30PM +0200, Reinhard Max wrote:
>
> On Wed, 1 Jun 2011 at 21:03, David Miller wrote:
>
> >Since we haven't been validating the sin_family field for 18+ years,
> >the chance to break some applications is very real.
> >
> >But I think it's more important to fix this (and force any broken
> >apps to set sin_family correctly). So I will apply this, thanks.
>
> I think a corresponding check should also go into inet6_bind() in
> net/ipv6/af_inet6.c .
Good idea,
Same check as for IPv4, also do for IPv6.
(If you passed in a IPv4 sockaddr_in here, the sizeof check
in the line before would have triggered already though.)
Signed-off-by: Marcus Meissner <meissner@suse.de>
Cc: Reinhard Max <max@suse.de>
Ciao, Marcus
---
net/ipv6/af_inet6.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index b7919f9..d450a2f 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -272,6 +272,10 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
if (addr_len < SIN6_LEN_RFC2133)
return -EINVAL;
+
+ if (addr->sin6_family != AF_INET6)
+ return -EINVAL;
+
addr_type = ipv6_addr_type(&addr->sin6_addr);
if ((addr_type & IPV6_ADDR_MULTICAST) && sock->type == SOCK_STREAM)
return -EINVAL;
--
1.7.4.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs
2011-06-06 16:00 ` [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs Marcus Meissner
@ 2011-06-06 21:48 ` David Miller
2011-06-07 7:25 ` Reinhard Max
1 sibling, 0 replies; 6+ messages in thread
From: David Miller @ 2011-06-06 21:48 UTC (permalink / raw)
To: meissner; +Cc: max, netdev
From: Marcus Meissner <meissner@suse.de>
Date: Mon, 6 Jun 2011 18:00:07 +0200
> On Mon, Jun 06, 2011 at 03:47:30PM +0200, Reinhard Max wrote:
>>
>> On Wed, 1 Jun 2011 at 21:03, David Miller wrote:
>>
>> >Since we haven't been validating the sin_family field for 18+ years,
>> >the chance to break some applications is very real.
>> >
>> >But I think it's more important to fix this (and force any broken
>> >apps to set sin_family correctly). So I will apply this, thanks.
>>
>> I think a corresponding check should also go into inet6_bind() in
>> net/ipv6/af_inet6.c .
>
> Good idea,
>
> Same check as for IPv4, also do for IPv6.
>
> (If you passed in a IPv4 sockaddr_in here, the sizeof check
> in the line before would have triggered already though.)
>
> Signed-off-by: Marcus Meissner <meissner@suse.de>
> Cc: Reinhard Max <max@suse.de>
Applied, thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs
2011-06-06 16:00 ` [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs Marcus Meissner
2011-06-06 21:48 ` David Miller
@ 2011-06-07 7:25 ` Reinhard Max
1 sibling, 0 replies; 6+ messages in thread
From: Reinhard Max @ 2011-06-07 7:25 UTC (permalink / raw)
To: Marcus Meissner; +Cc: David Miller, netdev
On Mon, 6 Jun 2011 at 18:00, Marcus Meissner wrote:
> Same check as for IPv4, also do for IPv6.
> [...]
> +
> + if (addr->sin6_family != AF_INET6)
> + return -EINVAL;
> +
According to the POSIX manpage for bind(), the error code should be
EAFNOSUPPORT ("The specified address is not a valid address for the
address family of the specified socket"). This would also match the
error code of connect() in the same situation.
And I think the family should be checked before the length for both,
bind() and connect(), to get more descriptive error messages when
passing an address of the wrong family.
cu
Reinhard
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-06-07 7:25 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-05-25 15:59 Bad behaviour when unintentionally mixing ipv4 and ipv6 addresses Marcus Meissner
2011-06-02 4:03 ` David Miller
2011-06-06 13:47 ` Reinhard Max
2011-06-06 16:00 ` [PATCH] net/ipv6: check for mistakenly passed in non-AF_INET6 sockaddrs Marcus Meissner
2011-06-06 21:48 ` David Miller
2011-06-07 7:25 ` Reinhard Max
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).