[bpf-next,v3,5/5] selftests: bpf: test writable buffers in raw tps
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Message ID 20190419210409.5021-6-mmullins@fb.com
State New
Headers show
Series
  • Untitled series #108149
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Commit Message

Matt Mullins April 19, 2019, 9:04 p.m. UTC
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>
---
 include/trace/events/bpf_test_run.h           | 50 ++++++++++++
 net/bpf/test_run.c                            |  4 +
 .../raw_tp_writable_reject_nbd_invalid.c      | 40 ++++++++++
 .../bpf/prog_tests/raw_tp_writable_test_run.c | 80 +++++++++++++++++++
 .../selftests/bpf/verifier/raw_tp_writable.c  | 34 ++++++++
 5 files changed, 208 insertions(+)
 create mode 100644 include/trace/events/bpf_test_run.h
 create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
 create mode 100644 tools/testing/selftests/bpf/verifier/raw_tp_writable.c

Comments

Yonghong Song April 22, 2019, 6:32 p.m. UTC | #1
On 4/19/19 2:04 PM, Matt Mullins wrote:
> 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>
> ---
>   include/trace/events/bpf_test_run.h           | 50 ++++++++++++
>   net/bpf/test_run.c                            |  4 +
>   .../raw_tp_writable_reject_nbd_invalid.c      | 40 ++++++++++
>   .../bpf/prog_tests/raw_tp_writable_test_run.c | 80 +++++++++++++++++++
>   .../selftests/bpf/verifier/raw_tp_writable.c  | 34 ++++++++
>   5 files changed, 208 insertions(+)
>   create mode 100644 include/trace/events/bpf_test_run.h
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
>   create mode 100644 tools/testing/selftests/bpf/verifier/raw_tp_writable.c
> 
> diff --git a/include/trace/events/bpf_test_run.h b/include/trace/events/bpf_test_run.h
> new file mode 100644
> index 000000000000..abf466839ea4
> --- /dev/null
> +++ b/include/trace/events/bpf_test_run.h
> @@ -0,0 +1,50 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM bpf_test_run
> +
> +#if !defined(_TRACE_NBD_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>
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index fab142b796ef..25e757102595 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -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;
>   }
>   
> diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
> new file mode 100644
> index 000000000000..328d5c4b084b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
> @@ -0,0 +1,40 @@
> +// 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),
> +		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_6, 128),

The number "128" is a little cryptic. Maybe you can use something like
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 loaded",
> +		  "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 opened",
> +		  "erroneously succeeded\n"))
> +		goto out_bpffd;
> +
> +	close(tp_fd);
> +out_bpffd:
> +	close(bpf_fd);
> +}
> diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
> new file mode 100644
> index 000000000000..4145925f9cab
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
> @@ -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_LD_IMM64(BPF_REG_0, 42),
You can use BPF_MOV64_IMM(BPF_REG_0, 42) instead of BPF_LD_IMM64.
BPF_LD_IMM64 is fine, but probably BPF_MOV64_IMM is better.
The same for a few below instances.

> +		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_LD_IMM64(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);
> +}
> diff --git a/tools/testing/selftests/bpf/verifier/raw_tp_writable.c b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
> new file mode 100644
> index 000000000000..95b5d70a1dc1
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
> @@ -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)",
> +},
>
Matt Mullins April 22, 2019, 7:27 p.m. UTC | #2
On Mon, 2019-04-22 at 18:32 +0000, Yonghong Song wrote:
> 
> On 4/19/19 2:04 PM, Matt Mullins wrote:
> > 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>
> > ---
> >   include/trace/events/bpf_test_run.h           | 50 ++++++++++++
> >   net/bpf/test_run.c                            |  4 +
> >   .../raw_tp_writable_reject_nbd_invalid.c      | 40 ++++++++++
> >   .../bpf/prog_tests/raw_tp_writable_test_run.c | 80 +++++++++++++++++++
> >   .../selftests/bpf/verifier/raw_tp_writable.c  | 34 ++++++++
> >   5 files changed, 208 insertions(+)
> >   create mode 100644 include/trace/events/bpf_test_run.h
> >   create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
> >   create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
> >   create mode 100644 tools/testing/selftests/bpf/verifier/raw_tp_writable.c
> > 
> > diff --git a/include/trace/events/bpf_test_run.h b/include/trace/events/bpf_test_run.h
> > new file mode 100644
> > index 000000000000..abf466839ea4
> > --- /dev/null
> > +++ b/include/trace/events/bpf_test_run.h
> > @@ -0,0 +1,50 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#undef TRACE_SYSTEM
> > +#define TRACE_SYSTEM bpf_test_run
> > +
> > +#if !defined(_TRACE_NBD_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>
> > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> > index fab142b796ef..25e757102595 100644
> > --- a/net/bpf/test_run.c
> > +++ b/net/bpf/test_run.c
> > @@ -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;
> >   }
> >   
> > diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
> > new file mode 100644
> > index 000000000000..328d5c4b084b
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
> > @@ -0,0 +1,40 @@
> > +// 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),
> > +		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_6, 128),
> 
> The number "128" is a little cryptic. Maybe you can use something like
> sizeof(struct nbd_request)?

That was explicitly chosen to be (far) larger than an nbd_request, as
this program should be rejected by the verifier.  If you really want, I
can do `sizeof(struct nbd_request) + some constant` and add a comment. 
But the size of an nbd request should never change, as that's a network
protocol.

> 
> > +		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 loaded",
> > +		  "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 opened",
> > +		  "erroneously succeeded\n"))
> > +		goto out_bpffd;
> > +
> > +	close(tp_fd);
> > +out_bpffd:
> > +	close(bpf_fd);
> > +}
> > diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
> > new file mode 100644
> > index 000000000000..4145925f9cab
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
> > @@ -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_LD_IMM64(BPF_REG_0, 42),
> 
> You can use BPF_MOV64_IMM(BPF_REG_0, 42) instead of BPF_LD_IMM64.
> BPF_LD_IMM64 is fine, but probably BPF_MOV64_IMM is better.
> The same for a few below instances.

Ah, right.  I don't need the second opcode if the value can be zero-
extended.

> 
> > +		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_LD_IMM64(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);
> > +}
> > diff --git a/tools/testing/selftests/bpf/verifier/raw_tp_writable.c b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
> > new file mode 100644
> > index 000000000000..95b5d70a1dc1
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
> > @@ -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)",
> > +},
> >
Yonghong Song April 22, 2019, 9:13 p.m. UTC | #3
On 4/22/19 12:27 PM, Matt Mullins wrote:
> On Mon, 2019-04-22 at 18:32 +0000, Yonghong Song wrote:
>>
>> On 4/19/19 2:04 PM, Matt Mullins wrote:
>>> 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>
>>> ---
>>>    include/trace/events/bpf_test_run.h           | 50 ++++++++++++
>>>    net/bpf/test_run.c                            |  4 +
>>>    .../raw_tp_writable_reject_nbd_invalid.c      | 40 ++++++++++
>>>    .../bpf/prog_tests/raw_tp_writable_test_run.c | 80 +++++++++++++++++++
>>>    .../selftests/bpf/verifier/raw_tp_writable.c  | 34 ++++++++
>>>    5 files changed, 208 insertions(+)
>>>    create mode 100644 include/trace/events/bpf_test_run.h
>>>    create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
>>>    create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
>>>    create mode 100644 tools/testing/selftests/bpf/verifier/raw_tp_writable.c
>>>
>>> diff --git a/include/trace/events/bpf_test_run.h b/include/trace/events/bpf_test_run.h
>>> new file mode 100644
>>> index 000000000000..abf466839ea4
>>> --- /dev/null
>>> +++ b/include/trace/events/bpf_test_run.h
>>> @@ -0,0 +1,50 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>> +#undef TRACE_SYSTEM
>>> +#define TRACE_SYSTEM bpf_test_run
>>> +
>>> +#if !defined(_TRACE_NBD_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>
>>> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
>>> index fab142b796ef..25e757102595 100644
>>> --- a/net/bpf/test_run.c
>>> +++ b/net/bpf/test_run.c
>>> @@ -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;
>>>    }
>>>    
>>> diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
>>> new file mode 100644
>>> index 000000000000..328d5c4b084b
>>> --- /dev/null
>>> +++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
>>> @@ -0,0 +1,40 @@
>>> +// 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),
>>> +		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_6, 128),
>>
>> The number "128" is a little cryptic. Maybe you can use something like
>> sizeof(struct nbd_request)?
> 
> That was explicitly chosen to be (far) larger than an nbd_request, as
> this program should be rejected by the verifier.  If you really want, I
> can do `sizeof(struct nbd_request) + some constant` and add a comment.
> But the size of an nbd request should never change, as that's a network
> protocol.

I think `sizeof(struct nbd_request) + some constant` is better than 
number `128`.

Patch
diff mbox series

diff --git a/include/trace/events/bpf_test_run.h b/include/trace/events/bpf_test_run.h
new file mode 100644
index 000000000000..abf466839ea4
--- /dev/null
+++ b/include/trace/events/bpf_test_run.h
@@ -0,0 +1,50 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM bpf_test_run
+
+#if !defined(_TRACE_NBD_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>
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index fab142b796ef..25e757102595 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -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;
 }
 
diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
new file mode 100644
index 000000000000..328d5c4b084b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_reject_nbd_invalid.c
@@ -0,0 +1,40 @@ 
+// 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),
+		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_6, 128),
+		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 loaded",
+		  "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 opened",
+		  "erroneously succeeded\n"))
+		goto out_bpffd;
+
+	close(tp_fd);
+out_bpffd:
+	close(bpf_fd);
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
new file mode 100644
index 000000000000..4145925f9cab
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_writable_test_run.c
@@ -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_LD_IMM64(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_LD_IMM64(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);
+}
diff --git a/tools/testing/selftests/bpf/verifier/raw_tp_writable.c b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
new file mode 100644
index 000000000000..95b5d70a1dc1
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/raw_tp_writable.c
@@ -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)",
+},