From b6069a95706ca5738be3f5d90fd286cbd13ac695 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 7 Sep 2012 22:03:35 +0000 Subject: filter: add MOD operation Add a new ALU opcode, to compute a modulus. Commit ffe06c17afbbb 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: Eric Dumazet Suggested-by: George Bakos Cc: Jay Schulist Cc: Jiri Pirko Cc: Andi Kleen Signed-off-by: David S. Miller --- net/core/filter.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'net/core') diff --git a/net/core/filter.c b/net/core/filter.c index 907efd27ec7..fbe3a8d1257 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -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: -- cgit v1.2.3-70-g09d2