Patchwork ipvs: Add boundary check on ioctl arguments

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Submitter Arjan van de Ven
Date Sept. 30, 2009, 11:11 a.m.
Message ID <20090930131109.2b3f71b8@infradead.org>
Download mbox | patch
Permalink /patch/34541/
State Not Applicable
Delegated to: David Miller
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Comments

Arjan van de Ven - Sept. 30, 2009, 11:11 a.m.
From 761a182f96b3707e1fee44e1079ba227e48745d1 Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@linux.intel.com>
Date: Wed, 30 Sep 2009 13:05:51 +0200
Subject: [PATCH] ipvs: Add boundary check on ioctl arguments

The ipvs code has a nifty system for doing the size of ioctl command copies;
it defines an array with values into which it indexes the cmd to find the
right length.

Unfortunately, the ipvs code forgot to check if the cmd was in the range
that the array provides, allowing for an index outside of the array,
which then gives a "garbage" result into the length, which then gets
used for copying into a stack buffer.

Fix this by adding sanity checks on these as well as the copy size.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
 net/netfilter/ipvs/ip_vs_ctl.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
Hannes Eder - Sept. 30, 2009, 1:38 p.m.
[cc: +Simon Horman]

Arjan van de Ven wrote:
 > From 761a182f96b3707e1fee44e1079ba227e48745d1 Mon Sep 17 00:00:00 2001
 > From: Arjan van de Ven <arjan@linux.intel.com>
 > Date: Wed, 30 Sep 2009 13:05:51 +0200
 > Subject: [PATCH] ipvs: Add boundary check on ioctl arguments
 >
 > The ipvs code has a nifty system for doing the size of ioctl command copies;
 > it defines an array with values into which it indexes the cmd to find the
 > right length.
 >
 > Unfortunately, the ipvs code forgot to check if the cmd was in the range
 > that the array provides, allowing for an index outside of the array,
 > which then gives a "garbage" result into the length, which then gets
 > used for copying into a stack buffer.
 >
 > Fix this by adding sanity checks on these as well as the copy size.
 >
 > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
 > ---
 >  net/netfilter/ipvs/ip_vs_ctl.c |   14 +++++++++++++-
 >  1 files changed, 13 insertions(+), 1 deletions(-)
 >
 > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
 > index ac624e5..3c52796 100644
 > --- a/net/netfilter/ipvs/ip_vs_ctl.c
 > +++ b/net/netfilter/ipvs/ip_vs_ctl.c
 > @@ -2077,6 +2077,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user 
*user, unsigned int len)
 >  	if (!capable(CAP_NET_ADMIN))
 >  		return -EPERM;
 >
 > +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX + 1)
 > +		return -EINVAL;
 > +	if (len < 0 || len >  MAX_ARG_LEN)
 > +		return -EINVAL;
 >  	if (len != set_arglen[SET_CMDID(cmd)]) {
 >  		pr_err("set_ctl: len %u != %u\n",
 >  		       len, set_arglen[SET_CMDID(cmd)]);
 > @@ -2353,17 +2357,25 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user 
*user, int *len)
 >  {
 >  	unsigned char arg[128];

can MAX_ARG_LEN be used here?

 >  	int ret = 0;
 > +	unsigned int copylen;
 >
 >  	if (!capable(CAP_NET_ADMIN))
 >  		return -EPERM;
 >
 > +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX + 1)
 > +		return -EINVAL;
 > +
 >  	if (*len < get_arglen[GET_CMDID(cmd)]) {
 >  		pr_err("get_ctl: len %u < %u\n",
 >  		       *len, get_arglen[GET_CMDID(cmd)]);
 >  		return -EINVAL;
 >  	}
 >
 > -	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) != 0)
 > +	copylen = get_arglen[GET_CMDID(cmd)];
 > +	if (copylen > 128)

I think it's better to use 'copylen > sizeof(arg)' here.

 > +		return -EINVAL;
 > +
 > +	if (copy_from_user(arg, user, copylen) != 0)
 >  		return -EFAULT;
 >
 >  	if (mutex_lock_interruptible(&__ip_vs_mutex))

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Arjan van de Ven - Dec. 15, 2009, 6:17 a.m.
On Wed, 30 Sep 2009 13:11:09 +0200
Arjan van de Ven <arjan@infradead.org> wrote:

ping on the patch below.... the warning is now triggered in mainline


> 
> >From 761a182f96b3707e1fee44e1079ba227e48745d1 Mon Sep 17 00:00:00
> >2001
> From: Arjan van de Ven <arjan@linux.intel.com>
> Date: Wed, 30 Sep 2009 13:05:51 +0200
> Subject: [PATCH] ipvs: Add boundary check on ioctl arguments
> 
> The ipvs code has a nifty system for doing the size of ioctl command
> copies; it defines an array with values into which it indexes the cmd
> to find the right length.
> 
> Unfortunately, the ipvs code forgot to check if the cmd was in the
> range that the array provides, allowing for an index outside of the
> array, which then gives a "garbage" result into the length, which
> then gets used for copying into a stack buffer.
> 
> Fix this by adding sanity checks on these as well as the copy size.
> 
> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
> ---
>  net/netfilter/ipvs/ip_vs_ctl.c |   14 +++++++++++++-
>  1 files changed, 13 insertions(+), 1 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c
> b/net/netfilter/ipvs/ip_vs_ctl.c index ac624e5..3c52796 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -2077,6 +2077,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd,
> void __user *user, unsigned int len) if (!capable(CAP_NET_ADMIN))
>  		return -EPERM;
>  
> +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX + 1)
> +		return -EINVAL;
> +	if (len < 0 || len >  MAX_ARG_LEN)
> +		return -EINVAL;
>  	if (len != set_arglen[SET_CMDID(cmd)]) {
>  		pr_err("set_ctl: len %u != %u\n",
>  		       len, set_arglen[SET_CMDID(cmd)]);
> @@ -2353,17 +2357,25 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd,
> void __user *user, int *len) {
>  	unsigned char arg[128];
>  	int ret = 0;
> +	unsigned int copylen;
>  
>  	if (!capable(CAP_NET_ADMIN))
>  		return -EPERM;
>  
> +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX + 1)
> +		return -EINVAL;
> +
>  	if (*len < get_arglen[GET_CMDID(cmd)]) {
>  		pr_err("get_ctl: len %u < %u\n",
>  		       *len, get_arglen[GET_CMDID(cmd)]);
>  		return -EINVAL;
>  	}
>  
> -	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) !=
> 0)
> +	copylen = get_arglen[GET_CMDID(cmd)];
> +	if (copylen > 128)
> +		return -EINVAL;
> +
> +	if (copy_from_user(arg, user, copylen) != 0)
>  		return -EFAULT;
>  
>  	if (mutex_lock_interruptible(&__ip_vs_mutex))
Simon Horman - Dec. 15, 2009, 6:32 a.m.
On Mon, Dec 14, 2009 at 10:17:04PM -0800, Arjan van de Ven wrote:
> On Wed, 30 Sep 2009 13:11:09 +0200
> Arjan van de Ven <arjan@infradead.org> wrote:
> 
> ping on the patch below.... the warning is now triggered in mainline

Hi Arjan,

could you address the comments Julian made about this?
http://lkml.indiana.edu/hypermail/linux/kernel/0910.0/00852.html

	OK, you can add my signed-off line after changing
	'cmd > ...MAX + 1' to 'cmd > ...MAX' at both
	places, nf_sockopt_ops ranges are [optmin ... optmax)

	May be comments should be changed because:

	- i'm not the author but after ispection we do not see any holes,
	we do not want users to upgrade just for this change
	- the cmd checks are just to help code checking tools
	- the len checks should help programmers (may be BUG_ON is
	better, user does not deserve EINVAL for wrong set_arglen/get_arglen).
	Checks for *len and len are not needed.

	For example, for len checks this should be enough, before
	copy_from_user():

	in do_ip_vs_get_ctl check can be
	BUG_ON(get_arglen[GET_CMDID(cmd)] > sizeof(arg));

	in do_ip_vs_set_ctl check can be
	BUG_ON(set_arglen[SET_CMDID(cmd)] > sizeof(arg));

	Acked-by: Julian Anastasov <ja@ssi.bg>

> > >From 761a182f96b3707e1fee44e1079ba227e48745d1 Mon Sep 17 00:00:00
> > >2001
> > From: Arjan van de Ven <arjan@linux.intel.com>
> > Date: Wed, 30 Sep 2009 13:05:51 +0200
> > Subject: [PATCH] ipvs: Add boundary check on ioctl arguments
> > 
> > The ipvs code has a nifty system for doing the size of ioctl command
> > copies; it defines an array with values into which it indexes the cmd
> > to find the right length.
> > 
> > Unfortunately, the ipvs code forgot to check if the cmd was in the
> > range that the array provides, allowing for an index outside of the
> > array, which then gives a "garbage" result into the length, which
> > then gets used for copying into a stack buffer.
> > 
> > Fix this by adding sanity checks on these as well as the copy size.
> > 
> > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
> > ---
> >  net/netfilter/ipvs/ip_vs_ctl.c |   14 +++++++++++++-
> >  1 files changed, 13 insertions(+), 1 deletions(-)
> > 
> > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c
> > b/net/netfilter/ipvs/ip_vs_ctl.c index ac624e5..3c52796 100644
> > --- a/net/netfilter/ipvs/ip_vs_ctl.c
> > +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> > @@ -2077,6 +2077,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd,
> > void __user *user, unsigned int len) if (!capable(CAP_NET_ADMIN))
> >  		return -EPERM;
> >  
> > +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX + 1)
> > +		return -EINVAL;
> > +	if (len < 0 || len >  MAX_ARG_LEN)
> > +		return -EINVAL;
> >  	if (len != set_arglen[SET_CMDID(cmd)]) {
> >  		pr_err("set_ctl: len %u != %u\n",
> >  		       len, set_arglen[SET_CMDID(cmd)]);
> > @@ -2353,17 +2357,25 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd,
> > void __user *user, int *len) {
> >  	unsigned char arg[128];
> >  	int ret = 0;
> > +	unsigned int copylen;
> >  
> >  	if (!capable(CAP_NET_ADMIN))
> >  		return -EPERM;
> >  
> > +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX + 1)
> > +		return -EINVAL;
> > +
> >  	if (*len < get_arglen[GET_CMDID(cmd)]) {
> >  		pr_err("get_ctl: len %u < %u\n",
> >  		       *len, get_arglen[GET_CMDID(cmd)]);
> >  		return -EINVAL;
> >  	}
> >  
> > -	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) !=
> > 0)
> > +	copylen = get_arglen[GET_CMDID(cmd)];
> > +	if (copylen > 128)
> > +		return -EINVAL;
> > +
> > +	if (copy_from_user(arg, user, copylen) != 0)
> >  		return -EFAULT;
> >  
> >  	if (mutex_lock_interruptible(&__ip_vs_mutex))
> 
> 
> -- 
> Arjan van de Ven 	Intel Open Source Technology Centre
> For development, discussion and tips for power savings, 
> visit http://www.lesswatts.org
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
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Simon Horman - Dec. 24, 2009, 4:16 a.m.
On Tue, Dec 15, 2009 at 05:32:01PM +1100, Simon Horman wrote:
> On Mon, Dec 14, 2009 at 10:17:04PM -0800, Arjan van de Ven wrote:
> > On Wed, 30 Sep 2009 13:11:09 +0200
> > Arjan van de Ven <arjan@infradead.org> wrote:
> > 
> > ping on the patch below.... the warning is now triggered in mainline
> 
> Hi Arjan,
> 
> could you address the comments Julian made about this?
> http://lkml.indiana.edu/hypermail/linux/kernel/0910.0/00852.html
> 
> 	OK, you can add my signed-off line after changing
> 	'cmd > ...MAX + 1' to 'cmd > ...MAX' at both
> 	places, nf_sockopt_ops ranges are [optmin ... optmax)
> 
> 	May be comments should be changed because:
> 
> 	- i'm not the author but after ispection we do not see any holes,
> 	we do not want users to upgrade just for this change
> 	- the cmd checks are just to help code checking tools
> 	- the len checks should help programmers (may be BUG_ON is
> 	better, user does not deserve EINVAL for wrong set_arglen/get_arglen).
> 	Checks for *len and len are not needed.
> 
> 	For example, for len checks this should be enough, before
> 	copy_from_user():
> 
> 	in do_ip_vs_get_ctl check can be
> 	BUG_ON(get_arglen[GET_CMDID(cmd)] > sizeof(arg));
> 
> 	in do_ip_vs_set_ctl check can be
> 	BUG_ON(set_arglen[SET_CMDID(cmd)] > sizeof(arg));
> 
> 	Acked-by: Julian Anastasov <ja@ssi.bg>

Ping.

While I agree with Julian that the patch you suggest below
ought not to be necessary, I'm also happy with it if
cmd > IP_VS_SO_SET_MAX + 1 is changed to cmd > IP_VS_SO_SET_MAX.

> > > >From 761a182f96b3707e1fee44e1079ba227e48745d1 Mon Sep 17 00:00:00
> > > >2001
> > > From: Arjan van de Ven <arjan@linux.intel.com>
> > > Date: Wed, 30 Sep 2009 13:05:51 +0200
> > > Subject: [PATCH] ipvs: Add boundary check on ioctl arguments
> > > 
> > > The ipvs code has a nifty system for doing the size of ioctl command
> > > copies; it defines an array with values into which it indexes the cmd
> > > to find the right length.
> > > 
> > > Unfortunately, the ipvs code forgot to check if the cmd was in the
> > > range that the array provides, allowing for an index outside of the
> > > array, which then gives a "garbage" result into the length, which
> > > then gets used for copying into a stack buffer.
> > > 
> > > Fix this by adding sanity checks on these as well as the copy size.
> > > 
> > > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
> > > ---
> > >  net/netfilter/ipvs/ip_vs_ctl.c |   14 +++++++++++++-
> > >  1 files changed, 13 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/net/netfilter/ipvs/ip_vs_ctl.c
> > > b/net/netfilter/ipvs/ip_vs_ctl.c index ac624e5..3c52796 100644
> > > --- a/net/netfilter/ipvs/ip_vs_ctl.c
> > > +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> > > @@ -2077,6 +2077,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd,
> > > void __user *user, unsigned int len) if (!capable(CAP_NET_ADMIN))
> > >  		return -EPERM;
> > >  
> > > +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX + 1)
> > > +		return -EINVAL;
> > > +	if (len < 0 || len >  MAX_ARG_LEN)
> > > +		return -EINVAL;
> > >  	if (len != set_arglen[SET_CMDID(cmd)]) {
> > >  		pr_err("set_ctl: len %u != %u\n",
> > >  		       len, set_arglen[SET_CMDID(cmd)]);
> > > @@ -2353,17 +2357,25 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd,
> > > void __user *user, int *len) {
> > >  	unsigned char arg[128];
> > >  	int ret = 0;
> > > +	unsigned int copylen;
> > >  
> > >  	if (!capable(CAP_NET_ADMIN))
> > >  		return -EPERM;
> > >  
> > > +	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX + 1)
> > > +		return -EINVAL;
> > > +
> > >  	if (*len < get_arglen[GET_CMDID(cmd)]) {
> > >  		pr_err("get_ctl: len %u < %u\n",
> > >  		       *len, get_arglen[GET_CMDID(cmd)]);
> > >  		return -EINVAL;
> > >  	}
> > >  
> > > -	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) !=
> > > 0)
> > > +	copylen = get_arglen[GET_CMDID(cmd)];
> > > +	if (copylen > 128)
> > > +		return -EINVAL;
> > > +
> > > +	if (copy_from_user(arg, user, copylen) != 0)
> > >  		return -EFAULT;
> > >  
> > >  	if (mutex_lock_interruptible(&__ip_vs_mutex))
> > 
> > 
> > -- 
> > Arjan van de Ven 	Intel Open Source Technology Centre
> > For development, discussion and tips for power savings, 
> > visit http://www.lesswatts.org
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> --
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Patch

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index ac624e5..3c52796 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2077,6 +2077,10 @@  do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len)
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
+	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_SET_MAX + 1)
+		return -EINVAL;
+	if (len < 0 || len >  MAX_ARG_LEN)
+		return -EINVAL;
 	if (len != set_arglen[SET_CMDID(cmd)]) {
 		pr_err("set_ctl: len %u != %u\n",
 		       len, set_arglen[SET_CMDID(cmd)]);
@@ -2353,17 +2357,25 @@  do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 {
 	unsigned char arg[128];
 	int ret = 0;
+	unsigned int copylen;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
+	if (cmd < IP_VS_BASE_CTL || cmd > IP_VS_SO_GET_MAX + 1)
+		return -EINVAL;
+
 	if (*len < get_arglen[GET_CMDID(cmd)]) {
 		pr_err("get_ctl: len %u < %u\n",
 		       *len, get_arglen[GET_CMDID(cmd)]);
 		return -EINVAL;
 	}
 
-	if (copy_from_user(arg, user, get_arglen[GET_CMDID(cmd)]) != 0)
+	copylen = get_arglen[GET_CMDID(cmd)];
+	if (copylen > 128)
+		return -EINVAL;
+
+	if (copy_from_user(arg, user, copylen) != 0)
 		return -EFAULT;
 
 	if (mutex_lock_interruptible(&__ip_vs_mutex))