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filter: add XOR instruction for use with X/K

PATCH Applied Daniel Borkmann 3 participants 5 messages Sep 24, 2012

Subsystems (5)
Networking Network drivers BPF BPF core +1 more subsystems
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Daniel Borkmann

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#0 lore raw

PATCH 1/1 filter: add XOR instruction for use with X/K

BPF_S_ANC_ALU_XOR_X has been added a while ago, but as an 'ancillary' operation that is invoked through a negative offset in K within BPF load operations. Since BPF_MOD has recently been added, BPF_XOR should also be part of the common ALU operations. Removing BPF_S_ANC_ALU_XOR_X might not be an option since this is exposed to user space.

Signed-off-by Daniel Borkmann <[email protected]>
---
 include/linux/filter.h |    3 +++
 net/core/filter.c      |   12 +++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)
include/linux/filter.h +3 -0
index 3cf5fd5..2ded090 100644
@@ -75,6 +75,7 @@ struct sock_fprog {	/* Required for SO_ATTACH_FILTER. */
 #define         BPF_RSH         0x70
 #define         BPF_NEG         0x80
 #define		BPF_MOD		0x90
+#define		BPF_XOR		0xa0
 
 #define         BPF_JA          0x00
 #define         BPF_JEQ         0x10

@@ -204,6 +205,8 @@ enum {
 	BPF_S_ALU_AND_X,
 	BPF_S_ALU_OR_K,
 	BPF_S_ALU_OR_X,
+	BPF_S_ALU_XOR_K,
+	BPF_S_ALU_XOR_X,
 	BPF_S_ALU_LSH_K,
 	BPF_S_ALU_LSH_X,
 	BPF_S_ALU_RSH_K,
net/core/filter.c +9 -3
index fbe3a8d..3d92ebb 100644
@@ -187,6 +187,13 @@ unsigned int sk_run_filter(const struct sk_buff *skb,
 		case BPF_S_ALU_OR_K:
 			A |= K;
 			continue;
+		case BPF_S_ANC_ALU_XOR_X:
+		case BPF_S_ALU_XOR_X:
+			A ^= X;
+			continue;
+		case BPF_S_ALU_XOR_K:
+			A ^= K;
+			continue;
 		case BPF_S_ALU_LSH_X:
 			A <<= X;
 			continue;

@@ -334,9 +341,6 @@ load_b:
 		case BPF_S_ANC_CPU:
 			A = raw_smp_processor_id();
 			continue;
-		case BPF_S_ANC_ALU_XOR_X:
-			A ^= X;
-			continue;
 		case BPF_S_ANC_NLATTR: {
 			struct nlattr *nla;
 

@@ -483,6 +487,8 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
 		[BPF_ALU|BPF_AND|BPF_X]  = BPF_S_ALU_AND_X,
 		[BPF_ALU|BPF_OR|BPF_K]   = BPF_S_ALU_OR_K,
 		[BPF_ALU|BPF_OR|BPF_X]   = BPF_S_ALU_OR_X,
+		[BPF_ALU|BPF_XOR|BPF_K]  = BPF_S_ALU_XOR_K,
+		[BPF_ALU|BPF_XOR|BPF_X]  = BPF_S_ALU_XOR_X,
 		[BPF_ALU|BPF_LSH|BPF_K]  = BPF_S_ALU_LSH_K,
 		[BPF_ALU|BPF_LSH|BPF_X]  = BPF_S_ALU_LSH_X,
 		[BPF_ALU|BPF_RSH|BPF_K]  = BPF_S_ALU_RSH_K,
Acked-by on v1 1/1
#1 lore raw
Quoted 5 lines · Daniel Borkmann

BPF_S_ANC_ALU_XOR_X has been added a while ago, but as an 'ancillary' operation that is invoked through a negative offset in K within BPF load operations. Since BPF_MOD has recently been added, BPF_XOR should also be part of the common ALU operations. Removing BPF_S_ANC_ALU_XOR_X might not be an option since this is exposed to user space.

Please note we dont expose BPF_S_ANC_ALU_XOR_X to user space.

We expose SKF_AD_ALU_XOR_X instead.

But it seems easier to leave it to keep this patch small (not touching various JIT implementations, even if followup are welcomed)

Acked-by Eric Dumazet <[email protected]>
author
#2 lore raw
Quoted 10 lines · Eric Dumazet <[email protected]> [2012-09-24 15:43:48 +0200] wrote:
Quoted 5 lines · Daniel Borkmann

BPF_S_ANC_ALU_XOR_X has been added a while ago, but as an 'ancillary' operation that is invoked through a negative offset in K within BPF load operations. Since BPF_MOD has recently been added, BPF_XOR should also be part of the common ALU operations. Removing BPF_S_ANC_ALU_XOR_X might not be an option since this is exposed to user space.

Please note we dont expose BPF_S_ANC_ALU_XOR_X to user space.

We expose SKF_AD_ALU_XOR_X instead.

Indeed. Sorry for that typo.

Quoted 6 lines

But it seems easier to leave it to keep this patch small (not touching various JIT implementations, even if followup are welcomed)

Acked-by Eric Dumazet <[email protected]>
maintainer Applied
#3 lore raw
In reply to Eric Dumazet

From: Eric Dumazet <[email protected]>
Date: Mon, 24 Sep 2012 15:43:48 +0200

Quoted 7 lines · Daniel Borkmann
Quoted 5 lines

BPF_S_ANC_ALU_XOR_X has been added a while ago, but as an 'ancillary' operation that is invoked through a negative offset in K within BPF load operations. Since BPF_MOD has recently been added, BPF_XOR should also be part of the common ALU operations. Removing BPF_S_ANC_ALU_XOR_X might not be an option since this is exposed to user space.

Quoted 8 lines

Please note we dont expose BPF_S_ANC_ALU_XOR_X to user space.

We expose SKF_AD_ALU_XOR_X instead.

But it seems easier to leave it to keep this patch small (not touching various JIT implementations, even if followup are welcomed)

Acked-by Eric Dumazet <[email protected]>

I applied this, fixing the commit message to refer to SKF_AD_ALU_XOR_X instead of BPF_S_ANC_ALU_XOR_X.

author
#4 lore raw
Quoted 13 lines · David Miller <[email protected]> [2012-09-24 16:50:05 -0400] wrote:

From: Eric Dumazet <[email protected]>
Date: Mon, 24 Sep 2012 15:43:48 +0200

Quoted 11 lines · Daniel Borkmann
Quoted 5 lines

BPF_S_ANC_ALU_XOR_X has been added a while ago, but as an 'ancillary' operation that is invoked through a negative offset in K within BPF load operations. Since BPF_MOD has recently been added, BPF_XOR should also be part of the common ALU operations. Removing BPF_S_ANC_ALU_XOR_X might not be an option since this is exposed to user space.

Please note we dont expose BPF_S_ANC_ALU_XOR_X to user space.

We expose SKF_AD_ALU_XOR_X instead.

Quoted 7 lines
Quoted 4 lines

But it seems easier to leave it to keep this patch small (not touching various JIT implementations, even if followup are welcomed)

Acked-by Eric Dumazet <[email protected]>

I applied this, fixing the commit message to refer to SKF_AD_ALU_XOR_X instead of BPF_S_ANC_ALU_XOR_X.

Thanks David!