Commit b6069a95 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

filter: add MOD operation 



Add a new ALU opcode, to compute a modulus.

Commit ffe06c17 used an ancillary to implement XOR_X,
but here we reserve one of the available ALU opcode to implement both
MOD_X and MOD_K

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Suggested-by: default avatarGeorge Bakos <gbakos@alpinista.org>
Cc: Jay Schulist <jschlst@samba.org>
Cc: Jiri Pirko <jpirko@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c6bb8136

include/linux/filter.h

+4 −0
Original line number Diff line number Diff line
@@ -74,6 +74,8 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */ 
#define         BPF_LSH         0x60

#define         BPF_RSH         0x70

#define         BPF_NEG         0x80

#define		BPF_MOD		0x90



#define         BPF_JA          0x00

#define         BPF_JEQ         0x10

#define         BPF_JGT         0x20
@@ -196,6 +198,8 @@ enum { 
	BPF_S_ALU_MUL_K,

	BPF_S_ALU_MUL_X,

	BPF_S_ALU_DIV_X,

	BPF_S_ALU_MOD_K,

	BPF_S_ALU_MOD_X,

	BPF_S_ALU_AND_K,

	BPF_S_ALU_AND_X,

	BPF_S_ALU_OR_K,

net/core/filter.c

+15 −0
Original line number Diff line number Diff line
@@ -167,6 +167,14 @@ unsigned int sk_run_filter(const struct sk_buff *skb, 
		case BPF_S_ALU_DIV_K:

			A = reciprocal_divide(A, K);

			continue;

		case BPF_S_ALU_MOD_X:

			if (X == 0)

				return 0;

			A %= X;

			continue;

		case BPF_S_ALU_MOD_K:

			A %= K;

			continue;

		case BPF_S_ALU_AND_X:

			A &= X;

			continue;
@@ -469,6 +477,8 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen) 
		[BPF_ALU|BPF_MUL|BPF_K]  = BPF_S_ALU_MUL_K,

		[BPF_ALU|BPF_MUL|BPF_X]  = BPF_S_ALU_MUL_X,

		[BPF_ALU|BPF_DIV|BPF_X]  = BPF_S_ALU_DIV_X,

		[BPF_ALU|BPF_MOD|BPF_K]  = BPF_S_ALU_MOD_K,

		[BPF_ALU|BPF_MOD|BPF_X]  = BPF_S_ALU_MOD_X,

		[BPF_ALU|BPF_AND|BPF_K]  = BPF_S_ALU_AND_K,

		[BPF_ALU|BPF_AND|BPF_X]  = BPF_S_ALU_AND_X,

		[BPF_ALU|BPF_OR|BPF_K]   = BPF_S_ALU_OR_K,
@@ -531,6 +541,11 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen) 
				return -EINVAL;

			ftest->k = reciprocal_value(ftest->k);

			break;

		case BPF_S_ALU_MOD_K:

			/* check for division by zero */

			if (ftest->k == 0)

				return -EINVAL;

			break;

		case BPF_S_LD_MEM:

		case BPF_S_LDX_MEM:

		case BPF_S_ST:

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