[PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Michal Kubecek]

In ipcomp_compress(), sortirq is enabled too early, allowing the
per-cpu scratch buffer to be rewritten by ipcomp_decompress()
(called on the same CPU in softirq context) between populating
the buffer and copying the compressed data to the skb.

Add similar protection into ipcomp_decompress() as it can be
called from process context as well (even if such scenario seems
a bit artificial).

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 net/xfrm/xfrm_ipcomp.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 2906d52..96946fb 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -48,9 +48,11 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 	const int cpu = get_cpu();
 	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
 	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
-	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
+	int err;
 	int len;
 
+	local_bh_disable();
+	err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
 	if (err)
 		goto out;
 
@@ -103,6 +105,7 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 	err = 0;
 
 out:
+	local_bh_enable();
 	put_cpu();
 	return err;
 }
@@ -148,7 +151,6 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 
 	local_bh_disable();
 	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
-	local_bh_enable();
 	if (err)
 		goto out;
 
@@ -158,12 +160,14 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 	}
 
 	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
+	local_bh_enable();
 	put_cpu();
 
 	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 	return 0;
 
 out:
+	local_bh_enable();
 	put_cpu();
 	return err;
 }
-- 
1.8.1.4

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Steffen Klassert]

On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
> In ipcomp_compress(), sortirq is enabled too early, allowing the
> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> (called on the same CPU in softirq context) between populating
> the buffer and copying the compressed data to the skb.
> 
> Add similar protection into ipcomp_decompress() as it can be
> called from process context as well (even if such scenario seems
> a bit artificial).
> 
> Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
> ---
>  net/xfrm/xfrm_ipcomp.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
> index 2906d52..96946fb 100644
> --- a/net/xfrm/xfrm_ipcomp.c
> +++ b/net/xfrm/xfrm_ipcomp.c
> @@ -48,9 +48,11 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
>  	const int cpu = get_cpu();
>  	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
>  	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
> -	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
> +	int err;
>  	int len;
>  
> +	local_bh_disable();

Maybe we could disable the BHs before we fetch the percpu pointers.
Then we can use smp_processor_id() to get the cpu. With that we
could get rid of a (now useless) preempt_disable()/preempt_enable()
pair. Same could be done in ipcomp_compress().

Looks ok otherwise. Thanks!

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Fan Du]

On 2013年10月15日 16:33, Steffen Klassert wrote:
> On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
>> In ipcomp_compress(), sortirq is enabled too early, allowing the
>> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
>> (called on the same CPU in softirq context) between populating
>> the buffer and copying the compressed data to the skb.
>>
>> Add similar protection into ipcomp_decompress() as it can be
>> called from process context as well (even if such scenario seems
>> a bit artificial).
>>
>> Signed-off-by: Michal Kubecek<mkubecek@suse.cz>
>> ---
>>   net/xfrm/xfrm_ipcomp.c | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
>> index 2906d52..96946fb 100644
>> --- a/net/xfrm/xfrm_ipcomp.c
>> +++ b/net/xfrm/xfrm_ipcomp.c
>> @@ -48,9 +48,11 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
>>   	const int cpu = get_cpu();
>>   	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
>>   	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
>> -	int err = crypto_comp_decompress(tfm, start, plen, scratch,&dlen);
>> +	int err;
>>   	int len;
>>
>> +	local_bh_disable();
>
> Maybe we could disable the BHs before we fetch the percpu pointers.
> Then we can use smp_processor_id() to get the cpu. With that we
> could get rid of a (now useless) preempt_disable()/preempt_enable()
> pair. Same could be done in ipcomp_compress().

Is it possible that two tasks race scratch buffer when both of them trying to compress data
without preempt disabled? for example, when task A working on compression, then task B
with higher priority preempts task A, and try to touch scratch buffer, which leaves stale
data for task A after then.

I think we needs preempt disabled for such case, otherwise I overlook codes in somewhere else.

> Looks ok otherwise. Thanks!
>
> --
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>

-- 
浮沉随浪只记今朝笑

--fan

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Steffen Klassert]

On Tue, Oct 15, 2013 at 04:59:04PM +0800, Fan Du wrote:
> 
> 
> On 2013年10月15日 16:33, Steffen Klassert wrote:
> >
> >Maybe we could disable the BHs before we fetch the percpu pointers.
> >Then we can use smp_processor_id() to get the cpu. With that we
> >could get rid of a (now useless) preempt_disable()/preempt_enable()
> >pair. Same could be done in ipcomp_compress().
> 
> Is it possible that two tasks race scratch buffer when both of them trying to compress data
> without preempt disabled? for example, when task A working on compression, then task B
> with higher priority preempts task A, and try to touch scratch buffer, which leaves stale
> data for task A after then.
> 
> I think we needs preempt disabled for such case, otherwise I overlook codes in somewhere else.
> 

You overlook that preemption is disabled if the BHs are disabled.

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Michal Kubecek]

On Tue, Oct 15, 2013 at 10:33:48AM +0200, Steffen Klassert wrote:
> > diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
> > index 2906d52..96946fb 100644
> > --- a/net/xfrm/xfrm_ipcomp.c
> > +++ b/net/xfrm/xfrm_ipcomp.c
> > @@ -48,9 +48,11 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
> >  	const int cpu = get_cpu();
> >  	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
> >  	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
> > -	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
> > +	int err;
> >  	int len;
> >  
> > +	local_bh_disable();
> 
> Maybe we could disable the BHs before we fetch the percpu pointers.
> Then we can use smp_processor_id() to get the cpu. With that we
> could get rid of a (now useless) preempt_disable()/preempt_enable()
> pair. Same could be done in ipcomp_compress().

Sounds like a good idea. I'll send v2 after some basic testing.

                                                 Michal Kubecek

[PATCH ipsec v2] xfrm: prevent ipcomp scratch buffer race condition

[Michal Kubecek]

In ipcomp_compress(), sortirq is enabled too early, allowing the
per-cpu scratch buffer to be rewritten by ipcomp_decompress()
(called on the same CPU in softirq context) between populating
the buffer and copying the compressed data to the skb.

Add similar protection into ipcomp_decompress() as it can be
called from process context as well (even if such scenario seems
a bit artificial).

v2: as pointed out by Steffen Klassert, if we also move the
local_bh_disable() before reading the per-cpu pointers, we can
get rid of get_cpu()/put_cpu().

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 net/xfrm/xfrm_ipcomp.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 2906d52..9fe4f42 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -45,12 +45,17 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 	const int plen = skb->len;
 	int dlen = IPCOMP_SCRATCH_SIZE;
 	const u8 *start = skb->data;
-	const int cpu = get_cpu();
-	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
-	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
-	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
+	struct crypto_comp *tfm;
+	u8 *scratch;
+	int cpu;
+	int err;
 	int len;
 
+	local_bh_disable();
+	cpu = smp_processor_id();
+	scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
+	tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+	err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
 	if (err)
 		goto out;
 
@@ -103,7 +108,7 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 	err = 0;
 
 out:
-	put_cpu();
+	local_bh_enable();
 	return err;
 }
 
@@ -141,14 +146,16 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 	const int plen = skb->len;
 	int dlen = IPCOMP_SCRATCH_SIZE;
 	u8 *start = skb->data;
-	const int cpu = get_cpu();
-	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
-	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+	struct crypto_comp *tfm;
+	u8 *scratch;
+	int cpu;
 	int err;
 
 	local_bh_disable();
+	cpu = smp_processor_id();
+	scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
+	tfm = *per_cpu_ptr(ipcd->tfms, cpu);
 	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
-	local_bh_enable();
 	if (err)
 		goto out;
 
@@ -158,13 +165,13 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 	}
 
 	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
-	put_cpu();
+	local_bh_enable();
 
 	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 	return 0;
 
 out:
-	put_cpu();
+	local_bh_enable();
 	return err;
 }
 
-- 
1.8.1.4

Re: [PATCH ipsec v2] xfrm: prevent ipcomp scratch buffer race condition

[Eric Dumazet]

On Tue, 2013-10-15 at 23:40 +0200, Michal Kubecek wrote:
> In ipcomp_compress(), sortirq is enabled too early, allowing the
> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> (called on the same CPU in softirq context) between populating
> the buffer and copying the compressed data to the skb.
> 
> Add similar protection into ipcomp_decompress() as it can be
> called from process context as well (even if such scenario seems
> a bit artificial).
> 
> v2: as pointed out by Steffen Klassert, if we also move the
> local_bh_disable() before reading the per-cpu pointers, we can
> get rid of get_cpu()/put_cpu().
> 
> Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
> ---
>  net/xfrm/xfrm_ipcomp.c | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
> index 2906d52..9fe4f42 100644
> --- a/net/xfrm/xfrm_ipcomp.c
> +++ b/net/xfrm/xfrm_ipcomp.c
> @@ -45,12 +45,17 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
>  	const int plen = skb->len;
>  	int dlen = IPCOMP_SCRATCH_SIZE;
>  	const u8 *start = skb->data;
> -	const int cpu = get_cpu();
> -	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
> -	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
> -	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
> +	struct crypto_comp *tfm;
> +	u8 *scratch;
> +	int cpu;
> +	int err;
>  	int len;
>  
> +	local_bh_disable();
> +	cpu = smp_processor_id();
> +	scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
> +	tfm = *per_cpu_ptr(ipcd->tfms, cpu);

Have you tried this_cpu_ptr() instead ?

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Herbert Xu]

On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
> In ipcomp_compress(), sortirq is enabled too early, allowing the
> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> (called on the same CPU in softirq context) between populating
> the buffer and copying the compressed data to the skb.

Good catch.

> Add similar protection into ipcomp_decompress() as it can be
> called from process context as well (even if such scenario seems
> a bit artificial).

I don't think this is possible or otherwise xfrm_input will
dead-lock.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Steffen Klassert]

On Wed, Oct 16, 2013 at 08:32:05PM +0800, Herbert Xu wrote:
> On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
> > In ipcomp_compress(), sortirq is enabled too early, allowing the
> > per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> > (called on the same CPU in softirq context) between populating
> > the buffer and copying the compressed data to the skb.
> 
> Good catch.
> 
> > Add similar protection into ipcomp_decompress() as it can be
> > called from process context as well (even if such scenario seems
> > a bit artificial).
> 
> I don't think this is possible or otherwise xfrm_input will
> dead-lock.
> 

Michal, please incorporate the feedback from Herbert and Eric,
I'll take it into the ipsec tree then. Thanks!

[PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race condition

[Michal Kubecek]

In ipcomp_compress(), sortirq is enabled too early, allowing the
per-cpu scratch buffer to be rewritten by ipcomp_decompress()
(called on the same CPU in softirq context) between populating
the buffer and copying the compressed data to the skb.

v2: as pointed out by Steffen Klassert, if we also move the
local_bh_disable() before reading the per-cpu pointers, we can
get rid of get_cpu()/put_cpu().

v3: removed ipcomp_decompress part (as explained by Herbert Xu,
it cannot be called from process context), get rid of cpu
variable (thanks to Eric Dumazet)

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 net/xfrm/xfrm_ipcomp.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 2906d52..3be02b6 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -141,14 +141,14 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 	const int plen = skb->len;
 	int dlen = IPCOMP_SCRATCH_SIZE;
 	u8 *start = skb->data;
-	const int cpu = get_cpu();
-	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
-	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
+	struct crypto_comp *tfm;
+	u8 *scratch;
 	int err;
 
 	local_bh_disable();
+	scratch = *this_cpu_ptr(ipcomp_scratches);
+	tfm = *this_cpu_ptr(ipcd->tfms);
 	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
-	local_bh_enable();
 	if (err)
 		goto out;
 
@@ -158,13 +158,13 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 	}
 
 	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
-	put_cpu();
+	local_bh_enable();
 
 	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
 	return 0;
 
 out:
-	put_cpu();
+	local_bh_enable();
 	return err;
 }
 
-- 
1.8.1.4

Re: [PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race condition

[Eric Dumazet]

On Thu, 2013-10-17 at 15:07 +0200, Michal Kubecek wrote:
> In ipcomp_compress(), sortirq is enabled too early, allowing the
> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> (called on the same CPU in softirq context) between populating
> the buffer and copying the compressed data to the skb.
> 
> v2: as pointed out by Steffen Klassert, if we also move the
> local_bh_disable() before reading the per-cpu pointers, we can
> get rid of get_cpu()/put_cpu().
> 
> v3: removed ipcomp_decompress part (as explained by Herbert Xu,
> it cannot be called from process context), get rid of cpu
> variable (thanks to Eric Dumazet)
> 
> Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
> ---

Reviewed-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race condition

[Herbert Xu]

On Thu, Oct 17, 2013 at 06:38:37AM -0700, Eric Dumazet wrote:
> On Thu, 2013-10-17 at 15:07 +0200, Michal Kubecek wrote:
> > In ipcomp_compress(), sortirq is enabled too early, allowing the
> > per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> > (called on the same CPU in softirq context) between populating
> > the buffer and copying the compressed data to the skb.
> > 
> > v2: as pointed out by Steffen Klassert, if we also move the
> > local_bh_disable() before reading the per-cpu pointers, we can
> > get rid of get_cpu()/put_cpu().
> > 
> > v3: removed ipcomp_decompress part (as explained by Herbert Xu,
> > it cannot be called from process context), get rid of cpu
> > variable (thanks to Eric Dumazet)
> > 
> > Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
> > ---
> 
> Reviewed-by: Eric Dumazet <edumazet@google.com>

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH ipsec v3] xfrm: prevent ipcomp scratch buffer race condition

[Steffen Klassert]

On Thu, Oct 17, 2013 at 03:07:40PM +0200, Michal Kubecek wrote:
> In ipcomp_compress(), sortirq is enabled too early, allowing the
> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> (called on the same CPU in softirq context) between populating
> the buffer and copying the compressed data to the skb.
> 
> v2: as pointed out by Steffen Klassert, if we also move the
> local_bh_disable() before reading the per-cpu pointers, we can
> get rid of get_cpu()/put_cpu().
> 
> v3: removed ipcomp_decompress part (as explained by Herbert Xu,
> it cannot be called from process context), get rid of cpu
> variable (thanks to Eric Dumazet)
> 
> Signed-off-by: Michal Kubecek <mkubecek@suse.cz>

Applied to the ipsec tree, thanks everyone!

[PATCH ipsec-next] xfrm: use vmalloc_node() for percpu scratches

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

scratches are per cpu, we can use vmalloc_node() for proper
NUMA affinity.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/xfrm/xfrm_ipcomp.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 2906d52..b943c7f 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -220,8 +220,8 @@ static void ipcomp_free_scratches(void)
 
 static void * __percpu *ipcomp_alloc_scratches(void)
 {
-	int i;
 	void * __percpu *scratches;
+	int i;
 
 	if (ipcomp_scratch_users++)
 		return ipcomp_scratches;
@@ -233,7 +233,9 @@ static void * __percpu *ipcomp_alloc_scratches(void)
 	ipcomp_scratches = scratches;
 
 	for_each_possible_cpu(i) {
-		void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
+		void *scratch;
+
+		scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
 		if (!scratch)
 			return NULL;
 		*per_cpu_ptr(scratches, i) = scratch;

Re: [PATCH ipsec-next] xfrm: use vmalloc_node() for percpu scratches

[Herbert Xu]

On Fri, Oct 18, 2013 at 03:54:16AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> scratches are per cpu, we can use vmalloc_node() for proper
> NUMA affinity.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

I agree completely.

Thanks!
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH ipsec-next] xfrm: use vmalloc_node() for percpu scratches

[Steffen Klassert]

On Fri, Oct 18, 2013 at 03:54:16AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> scratches are per cpu, we can use vmalloc_node() for proper
> NUMA affinity.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied to ipsec-next, thanks a lot Eric!

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Michal Kubecek]

On Wed, Oct 16, 2013 at 08:32:05PM +0800, Herbert Xu wrote:
> On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
> 
> > Add similar protection into ipcomp_decompress() as it can be
> > called from process context as well (even if such scenario seems
> > a bit artificial).
> 
> I don't think this is possible or otherwise xfrm_input will
> dead-lock.

When I was thinking about this, I came with two situations when this
might IMHO happen:

1. We are sending a packet to ourselves; this could mean not only a
local loop but also e.g. a packets between an LXC container and the host
or between two LXC containers. While it doesn't make much sense to use
compression in such case, it might happen while testing a solution which
is going to be used in a normal setup later.

2. The packet was passed to tun/tap device by a userspace application.

Am I wrong?

                                                        Michal Kubecek

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Herbert Xu]

On Thu, Oct 17, 2013 at 01:01:49PM +0200, Michal Kubecek wrote:
>
> When I was thinking about this, I came with two situations when this
> might IMHO happen:
> 
> 1. We are sending a packet to ourselves; this could mean not only a
> local loop but also e.g. a packets between an LXC container and the host
> or between two LXC containers. While it doesn't make much sense to use
> compression in such case, it might happen while testing a solution which
> is going to be used in a normal setup later.
> 
> 2. The packet was passed to tun/tap device by a userspace application.
> 
> Am I wrong?

I hope so :) Because otherwise xfrm_input will surely dead-lock since
it uses spin_lock.

The cases you mentioned should all go through netif_rx which will
then do the processing in BH context.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

[Michal Kubecek]

On Thu, Oct 17, 2013 at 07:04:20PM +0800, Herbert Xu wrote:
V> On Thu, Oct 17, 2013 at 01:01:49PM +0200, Michal Kubecek wrote:
> > 
> > Am I wrong?
> 
> I hope so :) Because otherwise xfrm_input will surely dead-lock since
> it uses spin_lock.
> 
> The cases you mentioned should all go through netif_rx which will
> then do the processing in BH context.

You are right. Thank you for the correction.

Michal Kubecek