Commit 9df1c28b authored by Matt Mullins's avatar Matt Mullins Committed by Alexei Starovoitov
Browse files

bpf: add writable context for raw tracepoints 



This is an opt-in interface that allows a tracepoint to provide a safe
buffer that can be written from a BPF_PROG_TYPE_RAW_TRACEPOINT program.
The size of the buffer must be a compile-time constant, and is checked
before allowing a BPF program to attach to a tracepoint that uses this
feature.

The pointer to this buffer will be the first argument of tracepoints
that opt in; the pointer is valid and can be bpf_probe_read() by both
BPF_PROG_TYPE_RAW_TRACEPOINT and BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE
programs that attach to such a tracepoint, but the buffer to which it
points may only be written by the latter.

Signed-off-by: default avatarMatt Mullins <mmullins@fb.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 34b8ab09

include/linux/bpf.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -272,6 +272,7 @@ enum bpf_reg_type { 
	PTR_TO_SOCK_COMMON_OR_NULL, /* reg points to sock_common or NULL */

	PTR_TO_SOCK_COMMON_OR_NULL, /* reg points to sock_common or NULL */

	PTR_TO_TCP_SOCK,	 /* reg points to struct tcp_sock */

	PTR_TO_TCP_SOCK,	 /* reg points to struct tcp_sock */

	PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */

	PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */

	PTR_TO_TP_BUFFER,	 /* reg points to a writable raw tp's buffer */

};

};





/* The information passed from prog-specific *_is_valid_access

/* The information passed from prog-specific *_is_valid_access
@@ -361,6 +362,7 @@ struct bpf_prog_aux { 
	u32 used_map_cnt;

	u32 used_map_cnt;

	u32 max_ctx_offset;

	u32 max_ctx_offset;

	u32 max_pkt_offset;

	u32 max_pkt_offset;

	u32 max_tp_access;

	u32 stack_depth;

	u32 stack_depth;

	u32 id;

	u32 id;

	u32 func_cnt; /* used by non-func prog as the number of func progs */

	u32 func_cnt; /* used by non-func prog as the number of func progs */

include/linux/bpf_types.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -25,6 +25,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_KPROBE, kprobe) 
BPF_PROG_TYPE(BPF_PROG_TYPE_TRACEPOINT, tracepoint)

BPF_PROG_TYPE(BPF_PROG_TYPE_TRACEPOINT, tracepoint)

BPF_PROG_TYPE(BPF_PROG_TYPE_PERF_EVENT, perf_event)

BPF_PROG_TYPE(BPF_PROG_TYPE_PERF_EVENT, perf_event)

BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)

BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)

BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, raw_tracepoint_writable)

#endif

#endif

#ifdef CONFIG_CGROUP_BPF

#ifdef CONFIG_CGROUP_BPF

BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)

BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)

include/linux/tracepoint-defs.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -45,6 +45,7 @@ struct bpf_raw_event_map { 
	struct tracepoint	*tp;

	struct tracepoint	*tp;

	void			*bpf_func;

	void			*bpf_func;

	u32			num_args;

	u32			num_args;

	u32			writable_size;

} __aligned(32);

} __aligned(32);





#endif
 
#endif

include/trace/bpf_probe.h

+25 −2
Original line number Original line Diff line number Diff line
@@ -69,8 +69,7 @@ __bpf_trace_##call(void *__data, proto) \ 
 * to make sure that if the tracepoint handling changes, the

 * to make sure that if the tracepoint handling changes, the

 * bpf probe will fail to compile unless it too is updated.

 * bpf probe will fail to compile unless it too is updated.

 */

 */

#undef DEFINE_EVENT

#define __DEFINE_EVENT(template, call, proto, args, size)		\

#define DEFINE_EVENT(template, call, proto, args)			\

static inline void bpf_test_probe_##call(void)				\

static inline void bpf_test_probe_##call(void)				\

{									\

{									\

	check_trace_callback_type_##call(__bpf_trace_##template);	\

	check_trace_callback_type_##call(__bpf_trace_##template);	\
@@ -81,12 +80,36 @@ __bpf_trace_tp_map_##call = { \ 
	.tp		= &__tracepoint_##call,				\

	.tp		= &__tracepoint_##call,				\

	.bpf_func	= (void *)__bpf_trace_##template,		\

	.bpf_func	= (void *)__bpf_trace_##template,		\

	.num_args	= COUNT_ARGS(args),				\

	.num_args	= COUNT_ARGS(args),				\

	.writable_size	= size,						\

};

};





#define FIRST(x, ...) x



#undef DEFINE_EVENT_WRITABLE

#define DEFINE_EVENT_WRITABLE(template, call, proto, args, size)	\

static inline void bpf_test_buffer_##call(void)				\

{									\

	/* BUILD_BUG_ON() is ignored if the code is completely eliminated, but \

	 * BUILD_BUG_ON_ZERO() uses a different mechanism that is not	\

	 * dead-code-eliminated.					\

	 */								\

	FIRST(proto);							\

	(void)BUILD_BUG_ON_ZERO(size != sizeof(*FIRST(args)));		\

}									\

__DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), size)



#undef DEFINE_EVENT

#define DEFINE_EVENT(template, call, proto, args)			\

	__DEFINE_EVENT(template, call, PARAMS(proto), PARAMS(args), 0)





#undef DEFINE_EVENT_PRINT

#undef DEFINE_EVENT_PRINT

#define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\

#define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\

	DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))

	DEFINE_EVENT(template, name, PARAMS(proto), PARAMS(args))





#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)

#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)



#undef DEFINE_EVENT_WRITABLE

#undef __DEFINE_EVENT

#undef FIRST



#endif /* CONFIG_BPF_EVENTS */
 
#endif /* CONFIG_BPF_EVENTS */

include/uapi/linux/bpf.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -168,6 +168,7 @@ enum bpf_prog_type { 
	BPF_PROG_TYPE_SK_REUSEPORT,

	BPF_PROG_TYPE_SK_REUSEPORT,

	BPF_PROG_TYPE_FLOW_DISSECTOR,

	BPF_PROG_TYPE_FLOW_DISSECTOR,

	BPF_PROG_TYPE_CGROUP_SYSCTL,

	BPF_PROG_TYPE_CGROUP_SYSCTL,

	BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,

};

};





enum bpf_attach_type {

enum bpf_attach_type {

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