selftests: bpf: test writable buffers in raw tps

This tests that:
  * a BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE cannot be attached if it
    uses either:
    * a variable offset to the tracepoint buffer, or
    * an offset beyond the size of the tracepoint buffer
  * a tracer can modify the buffer provided when attached to a writable
    tracepoint in bpf_prog_test_run

Signed-off-by: Matt Mullins <mmullins@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Matt Mullins 2019-04-26 11:49:51 -07:00 committed by Alexei Starovoitov
parent 4635b0ae4d
commit e950e84336
5 changed files with 210 additions and 0 deletions

View File

@ -0,0 +1,50 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM bpf_test_run
#if !defined(_TRACE_BPF_TEST_RUN_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_BPF_TEST_RUN_H
#include <linux/tracepoint.h>
DECLARE_EVENT_CLASS(bpf_test_finish,
TP_PROTO(int *err),
TP_ARGS(err),
TP_STRUCT__entry(
__field(int, err)
),
TP_fast_assign(
__entry->err = *err;
),
TP_printk("bpf_test_finish with err=%d", __entry->err)
);
#ifdef DEFINE_EVENT_WRITABLE
#undef BPF_TEST_RUN_DEFINE_EVENT
#define BPF_TEST_RUN_DEFINE_EVENT(template, call, proto, args, size) \
DEFINE_EVENT_WRITABLE(template, call, PARAMS(proto), \
PARAMS(args), size)
#else
#undef BPF_TEST_RUN_DEFINE_EVENT
#define BPF_TEST_RUN_DEFINE_EVENT(template, call, proto, args, size) \
DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args))
#endif
BPF_TEST_RUN_DEFINE_EVENT(bpf_test_finish, bpf_test_finish,
TP_PROTO(int *err),
TP_ARGS(err),
sizeof(int)
);
#endif
/* This part must be outside protection */
#include <trace/define_trace.h>

View File

@ -13,6 +13,9 @@
#include <net/sock.h>
#include <net/tcp.h>
#define CREATE_TRACE_POINTS
#include <trace/events/bpf_test_run.h>
static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
u32 *retval, u32 *time)
{
@ -100,6 +103,7 @@ static int bpf_test_finish(const union bpf_attr *kattr,
if (err != -ENOSPC)
err = 0;
out:
trace_bpf_test_finish(&err);
return err;
}

View File

@ -0,0 +1,42 @@
// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include <linux/nbd.h>
void test_raw_tp_writable_reject_nbd_invalid(void)
{
__u32 duration = 0;
char error[4096];
int bpf_fd = -1, tp_fd = -1;
const struct bpf_insn program[] = {
/* r6 is our tp buffer */
BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
/* one byte beyond the end of the nbd_request struct */
BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_6,
sizeof(struct nbd_request)),
BPF_EXIT_INSN(),
};
struct bpf_load_program_attr load_attr = {
.prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
.license = "GPL v2",
.insns = program,
.insns_cnt = sizeof(program) / sizeof(struct bpf_insn),
.log_level = 2,
};
bpf_fd = bpf_load_program_xattr(&load_attr, error, sizeof(error));
if (CHECK(bpf_fd < 0, "bpf_raw_tracepoint_writable load",
"failed: %d errno %d\n", bpf_fd, errno))
return;
tp_fd = bpf_raw_tracepoint_open("nbd_send_request", bpf_fd);
if (CHECK(tp_fd >= 0, "bpf_raw_tracepoint_writable open",
"erroneously succeeded\n"))
goto out_bpffd;
close(tp_fd);
out_bpffd:
close(bpf_fd);
}

View File

@ -0,0 +1,80 @@
// SPDX-License-Identifier: GPL-2.0
#include <test_progs.h>
#include <linux/nbd.h>
void test_raw_tp_writable_test_run(void)
{
__u32 duration = 0;
char error[4096];
const struct bpf_insn trace_program[] = {
BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6, 0),
BPF_MOV64_IMM(BPF_REG_0, 42),
BPF_STX_MEM(BPF_W, BPF_REG_6, BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
struct bpf_load_program_attr load_attr = {
.prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
.license = "GPL v2",
.insns = trace_program,
.insns_cnt = sizeof(trace_program) / sizeof(struct bpf_insn),
.log_level = 2,
};
int bpf_fd = bpf_load_program_xattr(&load_attr, error, sizeof(error));
if (CHECK(bpf_fd < 0, "bpf_raw_tracepoint_writable loaded",
"failed: %d errno %d\n", bpf_fd, errno))
return;
const struct bpf_insn skb_program[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
struct bpf_load_program_attr skb_load_attr = {
.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
.license = "GPL v2",
.insns = skb_program,
.insns_cnt = sizeof(skb_program) / sizeof(struct bpf_insn),
};
int filter_fd =
bpf_load_program_xattr(&skb_load_attr, error, sizeof(error));
if (CHECK(filter_fd < 0, "test_program_loaded", "failed: %d errno %d\n",
filter_fd, errno))
goto out_bpffd;
int tp_fd = bpf_raw_tracepoint_open("bpf_test_finish", bpf_fd);
if (CHECK(tp_fd < 0, "bpf_raw_tracepoint_writable opened",
"failed: %d errno %d\n", tp_fd, errno))
goto out_filterfd;
char test_skb[128] = {
0,
};
__u32 prog_ret;
int err = bpf_prog_test_run(filter_fd, 1, test_skb, sizeof(test_skb), 0,
0, &prog_ret, 0);
CHECK(err != 42, "test_run",
"tracepoint did not modify return value\n");
CHECK(prog_ret != 0, "test_run_ret",
"socket_filter did not return 0\n");
close(tp_fd);
err = bpf_prog_test_run(filter_fd, 1, test_skb, sizeof(test_skb), 0, 0,
&prog_ret, 0);
CHECK(err != 0, "test_run_notrace",
"test_run failed with %d errno %d\n", err, errno);
CHECK(prog_ret != 0, "test_run_ret_notrace",
"socket_filter did not return 0\n");
out_filterfd:
close(filter_fd);
out_bpffd:
close(bpf_fd);
}

View File

@ -0,0 +1,34 @@
{
"raw_tracepoint_writable: reject variable offset",
.insns = {
/* r6 is our tp buffer */
BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
BPF_LD_MAP_FD(BPF_REG_1, 0),
/* move the key (== 0) to r10-8 */
BPF_MOV32_IMM(BPF_REG_0, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_0, 0),
/* lookup in the map */
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_map_lookup_elem),
/* exit clean if null */
BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
BPF_EXIT_INSN(),
/* shift the buffer pointer to a variable location */
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0),
BPF_ALU64_REG(BPF_ADD, BPF_REG_6, BPF_REG_0),
/* clobber whatever's there */
BPF_MOV64_IMM(BPF_REG_7, 4242),
BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_7, 0),
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
},
.fixup_map_hash_8b = { 1, },
.prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
.errstr = "R6 invalid variable buffer offset: off=0, var_off=(0x0; 0xffffffff)",
},