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filter: add MOD operation
Add a new ALU opcode, to compute a modulus.
Commit ffe06c17af
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 <edumazet@google.com>
Suggested-by: George 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: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
c6bb8136c9
commit
b6069a9570
2 changed files with 19 additions and 0 deletions
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@ -74,6 +74,8 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */
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#define BPF_LSH 0x60
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#define BPF_RSH 0x70
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#define BPF_NEG 0x80
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#define BPF_MOD 0x90
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#define BPF_JA 0x00
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#define BPF_JEQ 0x10
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#define BPF_JGT 0x20
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@ -196,6 +198,8 @@ enum {
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BPF_S_ALU_MUL_K,
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BPF_S_ALU_MUL_X,
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BPF_S_ALU_DIV_X,
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BPF_S_ALU_MOD_K,
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BPF_S_ALU_MOD_X,
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BPF_S_ALU_AND_K,
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BPF_S_ALU_AND_X,
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BPF_S_ALU_OR_K,
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@ -167,6 +167,14 @@ unsigned int sk_run_filter(const struct sk_buff *skb,
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case BPF_S_ALU_DIV_K:
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A = reciprocal_divide(A, K);
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continue;
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case BPF_S_ALU_MOD_X:
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if (X == 0)
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return 0;
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A %= X;
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continue;
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case BPF_S_ALU_MOD_K:
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A %= K;
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continue;
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case BPF_S_ALU_AND_X:
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A &= X;
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continue;
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@ -469,6 +477,8 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
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[BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
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[BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
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[BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
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[BPF_ALU|BPF_MOD|BPF_K] = BPF_S_ALU_MOD_K,
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[BPF_ALU|BPF_MOD|BPF_X] = BPF_S_ALU_MOD_X,
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[BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
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[BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
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[BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
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@ -531,6 +541,11 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
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return -EINVAL;
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ftest->k = reciprocal_value(ftest->k);
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break;
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case BPF_S_ALU_MOD_K:
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/* check for division by zero */
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if (ftest->k == 0)
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return -EINVAL;
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break;
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case BPF_S_LD_MEM:
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case BPF_S_LDX_MEM:
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case BPF_S_ST:
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