[Aoetools-discuss] [PATCH] Incorrect shelf/slot handling in BPF

[Catalin S. <cs...@us...>]

The BPF filter program currently included in vblade requires that the 
major and minor fields in a packet header either
- match server's major and minor addresses or
- be both all ones (0xffff and 0xff respectively)
This is against the AoE specification that requires that the two fields 
be tested separately. (as seen in aoe.c:368)
Proposed patch corrects this.

diff --git a/vblade/bpf.c b/vblade/bpf.c
--- a/vblade/bpf.c
+++ b/vblade/bpf.c
@@ -82,32 +82,27 @@
  {
      struct bpf_program *bpf_program;
      struct bpf_insn insns[] = {
-        /* Load the type into register */
+        /* CHECKTYPE: Load the type into register */
          BPF_STMT(BPF_LD+BPF_H+BPF_ABS, 12),
          /* Does it match AoE Type (0x88a2)? No, goto INVALID */
-        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0x88a2, 0, 12),
+        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0x88a2, 0, 10),
          /* Load the flags into register */
          BPF_STMT(BPF_LD+BPF_B+BPF_ABS, 14),
          /* Check to see if the Resp flag is set */
          BPF_STMT(BPF_ALU+BPF_AND+BPF_K, Resp),
          /* Yes, goto INVALID */
-        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 9),
-        /* Load the shelf number into register */
+        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0, 0, 7),
+        /* CHECKSHELF: Load the shelf number into register */
          BPF_STMT(BPF_LD+BPF_H+BPF_ABS, 16),
-        /* Does it match shelf number? No, goto CHECKBROADCAST */
-        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, shelf, 0, 2),
-        /* Load the slot number into register */
+        /* Does it match shelf number? Yes, goto CHECKSLOT */
+        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, shelf, 1, 0),
+        /* Does it match broadcast? No, goto INVALID */
+        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0xffff, 0, 4),
+        /* CHECKSLOT: Load the slot number into register */
          BPF_STMT(BPF_LD+BPF_B+BPF_ABS, 18),
          /* Does it match shelf number? Yes, goto VALID */
-        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, slot, 4, 0),
-        /* CHECKBROADCAST: is (shelf, slot) == (0xffff, 0xff)? */
-        /* Load the shelf number into register */
-        BPF_STMT(BPF_LD+BPF_H+BPF_ABS, 16),
-        /* Is it 0xffff? No, goto INVALID */
-        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0xffff, 0, 3),
-        /* Load the slot number into register */
-        BPF_STMT(BPF_LD+BPF_B+BPF_ABS, 18),
-        /* Is it 0xff? No, goto INVALID */
+        BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, slot, 1, 0),
+        /* Does it match broadcast? No, goto INVALID */
          BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0xff, 0, 1),
          /* VALID: return -1 (allow the packet to be read) */
          BPF_STMT(BPF_RET+BPF_K, -1),