提交 6832a333 编写于 作者: D David S. Miller

bpf: Handle multiple variable additions into packet pointers in verifier.

We must accumulate into reg->aux_off rather than use a plain assignment.

Add a test for this situation to test_align.
Reported-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
上级 844cf763
......@@ -1531,7 +1531,7 @@ static int check_packet_ptr_add(struct bpf_verifier_env *env,
dst_reg->id = ++env->id_gen;
/* something was added to pkt_ptr, set range to zero */
dst_reg->aux_off = dst_reg->off;
dst_reg->aux_off += dst_reg->off;
dst_reg->off = 0;
dst_reg->range = 0;
if (had_id)
......
......@@ -273,6 +273,20 @@ static struct bpf_align_test tests[] = {
BPF_EXIT_INSN(),
BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_5, 0),
/* Test multiple accumulations of unknown values
* into a packet pointer.
*/
BPF_MOV64_REG(BPF_REG_5, BPF_REG_2),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, 14),
BPF_ALU64_REG(BPF_ADD, BPF_REG_5, BPF_REG_6),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, 4),
BPF_ALU64_REG(BPF_ADD, BPF_REG_5, BPF_REG_6),
BPF_MOV64_REG(BPF_REG_4, BPF_REG_5),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4),
BPF_JMP_REG(BPF_JGE, BPF_REG_3, BPF_REG_4, 1),
BPF_EXIT_INSN(),
BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_5, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
......@@ -314,6 +328,29 @@ static struct bpf_align_test tests[] = {
* requirements.
*/
"23: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R4=pkt(id=2,off=18,r=18),aux_off_align=4 R5=pkt(id=2,off=14,r=18),aux_off_align=4 R6=inv54,min_align=4 R10=fp",
/* Constant offset is added to R5 packet pointer,
* resulting in reg->off value of 14.
*/
"26: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R4=inv,aux_off_align=4 R5=pkt(id=0,off=14,r=8) R6=inv54,min_align=4 R10=fp",
/* Variable offset is added to R5, resulting in an
* auxiliary offset of 14, and an auxiliary alignment of 4.
*/
"27: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R4=inv,aux_off_align=4 R5=pkt(id=3,off=0,r=0),aux_off=14,aux_off_align=4 R6=inv54,min_align=4 R10=fp",
/* Constant is added to R5 again, setting reg->off to 4. */
"28: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R4=inv,aux_off_align=4 R5=pkt(id=3,off=4,r=0),aux_off=14,aux_off_align=4 R6=inv54,min_align=4 R10=fp",
/* And once more we add a variable, which causes an accumulation
* of reg->off into reg->aux_off_align, with resulting value of
* 18. The auxiliary alignment stays at 4.
*/
"29: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R4=inv,aux_off_align=4 R5=pkt(id=4,off=0,r=0),aux_off=18,aux_off_align=4 R6=inv54,min_align=4 R10=fp",
/* At the time the word size load is performed from R5,
* it's total offset is NET_IP_ALIGN + reg->off (0) +
* reg->aux_off (18) which is 20. Then the variable offset
* is considered using reg->aux_off_align which is 4 and meets
* the load's requirements.
*/
"33: R0=pkt(id=0,off=8,r=8) R1=ctx R2=pkt(id=0,off=0,r=8) R3=pkt_end R4=pkt(id=4,off=4,r=4),aux_off=18,aux_off_align=4 R5=pkt(id=4,off=0,r=4),aux_off=18,aux_off_align=4 R6=inv54,min_align=4 R10=fp",
},
},
};
......
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