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Patch "bpf: try harder on clones when writing into skb" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Jul 6, 2016

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This is a note to let you know that I've just added the patch titled

bpf: try harder on clones when writing into skb

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
bpf-try-harder-on-clones-when-writing-into-skb.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Wed Jul 6 16:50:47 PDT 2016

From: Daniel Borkmann <[email protected]>
Date: Fri, 19 Feb 2016 23:05:25 +0100
Subject: bpf: try harder on clones when writing into skb

From: Daniel Borkmann <[email protected]>

[ Upstream commit 3697649ff29e0f647565eed04b27a7779c646a22 ]

When we're dealing with clones and the area is not writeable, try harder and get a copy via pskb_expand_head(). Replace also other occurences in tc actions with the new skb_try_make_writable().

Reported-by Ashhad Sheikh <[email protected]>
Signed-off-by Daniel Borkmann <[email protected]>
Acked-by Alexei Starovoitov <[email protected]>
Signed-off-by David S. Miller <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 include/linux/skbuff.h |    7 +++++++
 net/core/filter.c      |   18 ++++++++++--------
 net/sched/act_csum.c   |    8 ++------
 net/sched/act_nat.c    |   18 +++++-------------
 4 files changed, 24 insertions(+), 27 deletions(-)
include/linux/skbuff.h +7 -0
@@ -2564,6 +2564,13 @@ static inline int skb_clone_writable(con
 	       skb_headroom(skb) + len <= skb->hdr_len;
 }
 
+static inline int skb_try_make_writable(struct sk_buff *skb,
+					unsigned int write_len)
+{
+	return skb_cloned(skb) && !skb_clone_writable(skb, write_len) &&
+	       pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
+}
+
 static inline int __skb_cow(struct sk_buff *skb, unsigned int headroom,
 			    int cloned)
 {
net/core/filter.c +10 -8
@@ -1275,9 +1275,7 @@ static u64 bpf_skb_store_bytes(u64 r1, u
 	 */
 	if (unlikely((u32) offset > 0xffff || len > sizeof(buf)))
 		return -EFAULT;
-
-	if (unlikely(skb_cloned(skb) &&
-		     !skb_clone_writable(skb, offset + len)))
+	if (unlikely(skb_try_make_writable(skb, offset + len)))
 		return -EFAULT;
 
 	ptr = skb_header_pointer(skb, offset, len, buf);

@@ -1321,8 +1319,7 @@ static u64 bpf_l3_csum_replace(u64 r1, u
 	if (unlikely((u32) offset > 0xffff))
 		return -EFAULT;
 
-	if (unlikely(skb_cloned(skb) &&
-		     !skb_clone_writable(skb, offset + sizeof(sum))))
+	if (unlikely(skb_try_make_writable(skb, offset + sizeof(sum))))
 		return -EFAULT;
 
 	ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum);

@@ -1367,9 +1364,7 @@ static u64 bpf_l4_csum_replace(u64 r1, u
 
 	if (unlikely((u32) offset > 0xffff))
 		return -EFAULT;
-
-	if (unlikely(skb_cloned(skb) &&
-		     !skb_clone_writable(skb, offset + sizeof(sum))))
+	if (unlikely(skb_try_make_writable(skb, offset + sizeof(sum))))
 		return -EFAULT;
 
 	ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum);

@@ -1554,6 +1549,13 @@ bool bpf_helper_changes_skb_data(void *f
 		return true;
 	if (func == bpf_skb_vlan_pop)
 		return true;
+	if (func == bpf_skb_store_bytes)
+		return true;
+	if (func == bpf_l3_csum_replace)
+		return true;
+	if (func == bpf_l4_csum_replace)
+		return true;
+
 	return false;
 }
net/sched/act_csum.c +2 -6
@@ -105,9 +105,7 @@ static void *tcf_csum_skb_nextlayer(stru
 	int hl = ihl + jhl;
 
 	if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
-	    (skb_cloned(skb) &&
-	     !skb_clone_writable(skb, hl + ntkoff) &&
-	     pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+	    skb_try_make_writable(skb, hl + ntkoff))
 		return NULL;
 	else
 		return (void *)(skb_network_header(skb) + ihl);

@@ -365,9 +363,7 @@ static int tcf_csum_ipv4(struct sk_buff
 	}
 
 	if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
-		if (skb_cloned(skb) &&
-		    !skb_clone_writable(skb, sizeof(*iph) + ntkoff) &&
-		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+		if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff))
 			goto fail;
 
 		ip_send_check(ip_hdr(skb));
net/sched/act_nat.c +5 -13
@@ -126,9 +126,7 @@ static int tcf_nat(struct sk_buff *skb,
 		addr = iph->daddr;
 
 	if (!((old_addr ^ addr) & mask)) {
-		if (skb_cloned(skb) &&
-		    !skb_clone_writable(skb, sizeof(*iph) + noff) &&
-		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+		if (skb_try_make_writable(skb, sizeof(*iph) + noff))
 			goto drop;
 
 		new_addr &= mask;

@@ -156,9 +154,7 @@ static int tcf_nat(struct sk_buff *skb,
 		struct tcphdr *tcph;
 
 		if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
-		    (skb_cloned(skb) &&
-		     !skb_clone_writable(skb, ihl + sizeof(*tcph) + noff) &&
-		     pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+		    skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
 			goto drop;
 
 		tcph = (void *)(skb_network_header(skb) + ihl);

@@ -171,9 +167,7 @@ static int tcf_nat(struct sk_buff *skb,
 		struct udphdr *udph;
 
 		if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
-		    (skb_cloned(skb) &&
-		     !skb_clone_writable(skb, ihl + sizeof(*udph) + noff) &&
-		     pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+		    skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
 			goto drop;
 
 		udph = (void *)(skb_network_header(skb) + ihl);

@@ -213,10 +207,8 @@ static int tcf_nat(struct sk_buff *skb,
 		if ((old_addr ^ addr) & mask)
 			break;
 
-		if (skb_cloned(skb) &&
-		    !skb_clone_writable(skb, ihl + sizeof(*icmph) +
-					     sizeof(*iph) + noff) &&
-		    pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+		if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
+					  sizeof(*iph) + noff))
 			goto drop;
 
 		icmph = (void *)(skb_network_header(skb) + ihl);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/bpf-perf-delay-release-of-bpf-prog-after-grace-period.patch queue-4.4/bpf-try-harder-on-clones-when-writing-into-skb.patch