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Commit 62544ce8 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

bpf: fix bpf_perf_event_read() helper 



Fix safety checks for bpf_perf_event_read():
- only non-inherited events can be added to perf_event_array map
  (do this check statically at map insertion time)
- dynamically check that event is local and !pmu->count
Otherwise buggy bpf program can cause kernel splat.

Also fix error path after perf_event_attrs()
and remove redundant 'extern'.

Fixes: 35578d79 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter")
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Tested-by: default avatarWang Nan <wangnan0@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8b7c94e3

include/linux/bpf.h

+0 −1
Original line number Original line Diff line number Diff line
@@ -194,7 +194,6 @@ extern const struct bpf_func_proto bpf_map_lookup_elem_proto; 
extern const struct bpf_func_proto bpf_map_update_elem_proto;

extern const struct bpf_func_proto bpf_map_update_elem_proto;

extern const struct bpf_func_proto bpf_map_delete_elem_proto;

extern const struct bpf_func_proto bpf_map_delete_elem_proto;





extern const struct bpf_func_proto bpf_perf_event_read_proto;

extern const struct bpf_func_proto bpf_get_prandom_u32_proto;

extern const struct bpf_func_proto bpf_get_prandom_u32_proto;

extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;

extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;

extern const struct bpf_func_proto bpf_tail_call_proto;

extern const struct bpf_func_proto bpf_tail_call_proto;

kernel/bpf/arraymap.c

+16 −9
Original line number Original line Diff line number Diff line
@@ -292,17 +292,24 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd) 




	attr = perf_event_attrs(event);

	attr = perf_event_attrs(event);

	if (IS_ERR(attr))

	if (IS_ERR(attr))

		return (void *)attr;

		goto err;





	if (attr->type != PERF_TYPE_RAW &&

	if (attr->inherit)

	    !(attr->type == PERF_TYPE_SOFTWARE &&

		goto err;

	      attr->config == PERF_COUNT_SW_BPF_OUTPUT) &&



	    attr->type != PERF_TYPE_HARDWARE) {

	if (attr->type == PERF_TYPE_RAW)

		return event;



	if (attr->type == PERF_TYPE_HARDWARE)

		return event;



	if (attr->type == PERF_TYPE_SOFTWARE &&

	    attr->config == PERF_COUNT_SW_BPF_OUTPUT)

		return event;

err:

	perf_event_release_kernel(event);

	perf_event_release_kernel(event);

	return ERR_PTR(-EINVAL);

	return ERR_PTR(-EINVAL);

}

}

	return event;

}





static void perf_event_fd_array_put_ptr(void *ptr)

static void perf_event_fd_array_put_ptr(void *ptr)

{

{

kernel/trace/bpf_trace.c

+6 −1
Original line number Original line Diff line number Diff line
@@ -199,6 +199,11 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5) 
	if (!event)

	if (!event)

		return -ENOENT;

		return -ENOENT;





	/* make sure event is local and doesn't have pmu::count */

	if (event->oncpu != smp_processor_id() ||

	    event->pmu->count)

		return -EINVAL;



	/*

	/*

	 * we don't know if the function is run successfully by the

	 * we don't know if the function is run successfully by the

	 * return value. It can be judged in other places, such as

	 * return value. It can be judged in other places, such as
@@ -207,7 +212,7 @@ static u64 bpf_perf_event_read(u64 r1, u64 index, u64 r3, u64 r4, u64 r5) 
	return perf_event_read_local(event);

	return perf_event_read_local(event);

}

}





const struct bpf_func_proto bpf_perf_event_read_proto = {

static const struct bpf_func_proto bpf_perf_event_read_proto = {

	.func		= bpf_perf_event_read,

	.func		= bpf_perf_event_read,

	.gpl_only	= false,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.ret_type	= RET_INTEGER,