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bpf: add various tests around spill/fill of regs
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Add several spill/fill tests. Besides others, one that performs xadd
on the spilled register, one ldx/stx test where different types are
spilled from two branches and read out from common path. Verfier does
handle all correctly.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Daniel Borkmann authored and David S. Miller committed Oct 18, 2016
1 parent 1441dc9 commit 1a776b9
Showing 1 changed file with 116 additions and 0 deletions.
116 changes: 116 additions & 0 deletions samples/bpf/test_verifier.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
#include <linux/unistd.h>
#include <string.h>
#include <linux/filter.h>
#include <linux/bpf_perf_event.h>
#include <stddef.h>
#include <stdbool.h>
#include <sys/resource.h>
Expand Down Expand Up @@ -1127,6 +1128,108 @@ static struct bpf_test tests[] = {
.errstr = "invalid bpf_context access",
.result = REJECT,
},
{
"unpriv: spill/fill of ctx",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
},
{
"unpriv: spill/fill of ctx 2",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_hash_recalc),
BPF_EXIT_INSN(),
},
.result = ACCEPT,
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"unpriv: spill/fill of ctx 3",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_hash_recalc),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "R1 type=fp expected=ctx",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"unpriv: spill/fill of ctx 4",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_MOV64_IMM(BPF_REG_0, 1),
BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_10, BPF_REG_0, -8, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_get_hash_recalc),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "R1 type=inv expected=ctx",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"unpriv: spill/fill of different pointers stx",
.insns = {
BPF_MOV64_IMM(BPF_REG_3, 42),
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -16),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_2, 0),
BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_3,
offsetof(struct __sk_buff, mark)),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "same insn cannot be used with different pointers",
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
},
{
"unpriv: spill/fill of different pointers ldx",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2,
-(__s32)offsetof(struct bpf_perf_event_data,
sample_period) - 8),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_2, 0),
BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1,
offsetof(struct bpf_perf_event_data,
sample_period)),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.result = REJECT,
.errstr = "same insn cannot be used with different pointers",
.prog_type = BPF_PROG_TYPE_PERF_EVENT,
},
{
"unpriv: write pointer into map elem value",
.insns = {
Expand Down Expand Up @@ -1193,6 +1296,19 @@ static struct bpf_test tests[] = {
.errstr = "frame pointer is read only",
.result = REJECT,
},
{
"unpriv: spill/fill frame pointer",
.insns = {
BPF_ALU64_REG(BPF_MOV, BPF_REG_6, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, -8),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_10, 0),
BPF_LDX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.errstr = "frame pointer is read only",
.result = REJECT,
},
{
"unpriv: cmp of frame pointer",
.insns = {
Expand Down

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