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linux/tools/testing/selftests/bpf/verifier/spill_fill.c
Martin KaFai Lau c08455dec5 selftests/bpf: Verifier test on refill from a smaller spill 
This patch adds a verifier test to ensure the verifier can read 8 bytes
from the stack after two 32bit write at fp-4 and fp-8. The test is similar
to the reported case from bcc [0].

  [0] https://github.com/iovisor/bcc/pull/3683

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211102064541.316414-1-kafai@fb.com
2021-11-03 15:55:43 +01:00

285 lines
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{
"check valid spill/fill",
.insns = {
/* spill R1(ctx) into stack */
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
/* fill it back into R2 */
BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_10, -8),
/* should be able to access R0 = *(R2 + 8) */
/* BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_2, 8), */
BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
BPF_EXIT_INSN(),
},
.errstr_unpriv = "R0 leaks addr",
.result = ACCEPT,
.result_unpriv = REJECT,
.retval = POINTER_VALUE,
},
{
"check valid spill/fill, skb mark",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_1),
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0,
offsetof(struct __sk_buff, mark)),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
.result_unpriv = ACCEPT,
},
{
"check valid spill/fill, ptr to mem",
.insns = {
/* reserve 8 byte ringbuf memory */
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
BPF_LD_MAP_FD(BPF_REG_1, 0),
BPF_MOV64_IMM(BPF_REG_2, 8),
BPF_MOV64_IMM(BPF_REG_3, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
/* store a pointer to the reserved memory in R6 */
BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
/* check whether the reservation was successful */
BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6),
/* spill R6(mem) into the stack */
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
/* fill it back in R7 */
BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, -8),
/* should be able to access *(R7) = 0 */
BPF_ST_MEM(BPF_DW, BPF_REG_7, 0, 0),
/* submit the reserved ringbuf memory */
BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
BPF_MOV64_IMM(BPF_REG_2, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_submit),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.fixup_map_ringbuf = { 1 },
.result = ACCEPT,
.result_unpriv = ACCEPT,
},
{
"check corrupted spill/fill",
.insns = {
/* spill R1(ctx) into stack */
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
/* mess up with R1 pointer on stack */
BPF_ST_MEM(BPF_B, BPF_REG_10, -7, 0x23),
/* fill back into R0 is fine for priv.
* R0 now becomes SCALAR_VALUE.
*/
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
/* Load from R0 should fail. */
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 8),
BPF_EXIT_INSN(),
},
.errstr_unpriv = "attempt to corrupt spilled",
.errstr = "R0 invalid mem access 'inv",
.result = REJECT,
.flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
},
{
"check corrupted spill/fill, LSB",
.insns = {
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
BPF_ST_MEM(BPF_H, BPF_REG_10, -8, 0xcafe),
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
BPF_EXIT_INSN(),
},
.errstr_unpriv = "attempt to corrupt spilled",
.result_unpriv = REJECT,
.result = ACCEPT,
.retval = POINTER_VALUE,
},
{
"check corrupted spill/fill, MSB",
.insns = {
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0x12345678),
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
BPF_EXIT_INSN(),
},
.errstr_unpriv = "attempt to corrupt spilled",
.result_unpriv = REJECT,
.result = ACCEPT,
.retval = POINTER_VALUE,
},
{
"Spill and refill a u32 const scalar. Offset to skb->data",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
offsetof(struct __sk_buff, data)),
BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
offsetof(struct __sk_buff, data_end)),
/* r4 = 20 */
BPF_MOV32_IMM(BPF_REG_4, 20),
/* *(u32 *)(r10 -8) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* r4 = *(u32 *)(r10 -8) */
BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -8),
/* r0 = r2 */
BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv20 */
BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
/* if (r0 > r3) R0=pkt,off=20 R2=pkt R3=pkt_end R4=inv20 */
BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
/* r0 = *(u32 *)r2 R0=pkt,off=20,r=20 R2=pkt,r=20 R3=pkt_end R4=inv20 */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"Spill a u32 const, refill from another half of the uninit u32 from the stack",
.insns = {
/* r4 = 20 */
BPF_MOV32_IMM(BPF_REG_4, 20),
/* *(u32 *)(r10 -8) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* r4 = *(u32 *)(r10 -4) fp-8=????rrrr*/
BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -4),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "invalid read from stack off -4+0 size 4",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"Spill a u32 const scalar. Refill as u16. Offset to skb->data",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
offsetof(struct __sk_buff, data)),
BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
offsetof(struct __sk_buff, data_end)),
/* r4 = 20 */
BPF_MOV32_IMM(BPF_REG_4, 20),
/* *(u32 *)(r10 -8) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* r4 = *(u16 *)(r10 -8) */
BPF_LDX_MEM(BPF_H, BPF_REG_4, BPF_REG_10, -8),
/* r0 = r2 */
BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv,umax=65535 */
BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
/* if (r0 > r3) R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv,umax=65535 */
BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
/* r0 = *(u32 *)r2 R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv20 */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "invalid access to packet",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"Spill a u32 const scalar. Refill as u16 from fp-6. Offset to skb->data",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
offsetof(struct __sk_buff, data)),
BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
offsetof(struct __sk_buff, data_end)),
/* r4 = 20 */
BPF_MOV32_IMM(BPF_REG_4, 20),
/* *(u32 *)(r10 -8) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* r4 = *(u16 *)(r10 -6) */
BPF_LDX_MEM(BPF_H, BPF_REG_4, BPF_REG_10, -6),
/* r0 = r2 */
BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv,umax=65535 */
BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
/* if (r0 > r3) R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv,umax=65535 */
BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
/* r0 = *(u32 *)r2 R0=pkt,umax=65535 R2=pkt R3=pkt_end R4=inv20 */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "invalid access to packet",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"Spill and refill a u32 const scalar at non 8byte aligned stack addr. Offset to skb->data",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
offsetof(struct __sk_buff, data)),
BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
offsetof(struct __sk_buff, data_end)),
/* r4 = 20 */
BPF_MOV32_IMM(BPF_REG_4, 20),
/* *(u32 *)(r10 -8) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* *(u32 *)(r10 -4) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -4),
/* r4 = *(u32 *)(r10 -4), */
BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -4),
/* r0 = r2 */
BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
/* r0 += r4 R0=pkt R2=pkt R3=pkt_end R4=inv,umax=U32_MAX */
BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_4),
/* if (r0 > r3) R0=pkt,umax=U32_MAX R2=pkt R3=pkt_end R4=inv */
BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
/* r0 = *(u32 *)r2 R0=pkt,umax=U32_MAX R2=pkt R3=pkt_end R4=inv */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "invalid access to packet",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"Spill and refill a umax=40 bounded scalar. Offset to skb->data",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
offsetof(struct __sk_buff, data)),
BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
offsetof(struct __sk_buff, data_end)),
BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_1,
offsetof(struct __sk_buff, tstamp)),
BPF_JMP_IMM(BPF_JLE, BPF_REG_4, 40, 2),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
/* *(u32 *)(r10 -8) = r4 R4=inv,umax=40 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* r4 = (*u32 *)(r10 - 8) */
BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_10, -8),
/* r2 += r4 R2=pkt R4=inv,umax=40 */
BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_4),
/* r0 = r2 R2=pkt,umax=40 R4=inv,umax=40 */
BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
/* r2 += 20 R0=pkt,umax=40 R2=pkt,umax=40 */
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, 20),
/* if (r2 > r3) R0=pkt,umax=40 R2=pkt,off=20,umax=40 */
BPF_JMP_REG(BPF_JGT, BPF_REG_2, BPF_REG_3, 1),
/* r0 = *(u32 *)r0 R0=pkt,r=20,umax=40 R2=pkt,off=20,r=20,umax=40 */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"Spill a u32 scalar at fp-4 and then at fp-8",
.insns = {
/* r4 = 4321 */
BPF_MOV32_IMM(BPF_REG_4, 4321),
/* *(u32 *)(r10 -4) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -4),
/* *(u32 *)(r10 -8) = r4 */
BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_4, -8),
/* r4 = *(u64 *)(r10 -8) */
BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_10, -8),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
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