Commit f005afed authored by Yonghong Song's avatar Yonghong Song Committed by Daniel Borkmann
Browse files

trace/bpf: remove helper bpf_perf_prog_read_value from tracepoint type programs 



Commit 4bebdc7a ("bpf: add helper bpf_perf_prog_read_value")
added helper bpf_perf_prog_read_value so that perf_event type program
can read event counter and enabled/running time.
This commit, however, introduced a bug which allows this helper
for tracepoint type programs. This is incorrect as bpf_perf_prog_read_value
needs to access perf_event through its bpf_perf_event_data_kern type context,
which is not available for tracepoint type program.

This patch fixed the issue by separating bpf_func_proto between tracepoint
and perf_event type programs and removed bpf_perf_prog_read_value
from tracepoint func prototype.

Fixes: 4bebdc7a ("bpf: add helper bpf_perf_prog_read_value")
Reported-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 52fda36d

kernel/trace/bpf_trace.c

+40 −28
Original line number Diff line number Diff line
@@ -661,7 +661,41 @@ static const struct bpf_func_proto bpf_get_stackid_proto_tp = { 
	.arg3_type	= ARG_ANYTHING,

};



BPF_CALL_3(bpf_perf_prog_read_value_tp, struct bpf_perf_event_data_kern *, ctx,

static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)

{

	switch (func_id) {

	case BPF_FUNC_perf_event_output:

		return &bpf_perf_event_output_proto_tp;

	case BPF_FUNC_get_stackid:

		return &bpf_get_stackid_proto_tp;

	default:

		return tracing_func_proto(func_id);

	}

}



static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,

				    struct bpf_insn_access_aux *info)

{

	if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)

		return false;

	if (type != BPF_READ)

		return false;

	if (off % size != 0)

		return false;



	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));

	return true;

}



const struct bpf_verifier_ops tracepoint_verifier_ops = {

	.get_func_proto  = tp_prog_func_proto,

	.is_valid_access = tp_prog_is_valid_access,

};



const struct bpf_prog_ops tracepoint_prog_ops = {

};



BPF_CALL_3(bpf_perf_prog_read_value, struct bpf_perf_event_data_kern *, ctx,

	   struct bpf_perf_event_value *, buf, u32, size)

{

	int err = -EINVAL;
@@ -678,8 +712,8 @@ clear: 
	return err;

}



static const struct bpf_func_proto bpf_perf_prog_read_value_proto_tp = {

         .func           = bpf_perf_prog_read_value_tp,

static const struct bpf_func_proto bpf_perf_prog_read_value_proto = {

         .func           = bpf_perf_prog_read_value,

         .gpl_only       = true,

         .ret_type       = RET_INTEGER,

         .arg1_type      = ARG_PTR_TO_CTX,
@@ -687,7 +721,7 @@ static const struct bpf_func_proto bpf_perf_prog_read_value_proto_tp = { 
         .arg3_type      = ARG_CONST_SIZE,

};



static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id)

static const struct bpf_func_proto *pe_prog_func_proto(enum bpf_func_id func_id)

{

	switch (func_id) {

	case BPF_FUNC_perf_event_output:
@@ -695,34 +729,12 @@ static const struct bpf_func_proto *tp_prog_func_proto(enum bpf_func_id func_id) 
	case BPF_FUNC_get_stackid:

		return &bpf_get_stackid_proto_tp;

	case BPF_FUNC_perf_prog_read_value:

		return &bpf_perf_prog_read_value_proto_tp;

		return &bpf_perf_prog_read_value_proto;

	default:

		return tracing_func_proto(func_id);

	}

}



static bool tp_prog_is_valid_access(int off, int size, enum bpf_access_type type,

				    struct bpf_insn_access_aux *info)

{

	if (off < sizeof(void *) || off >= PERF_MAX_TRACE_SIZE)

		return false;

	if (type != BPF_READ)

		return false;

	if (off % size != 0)

		return false;



	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(__u64));

	return true;

}



const struct bpf_verifier_ops tracepoint_verifier_ops = {

	.get_func_proto  = tp_prog_func_proto,

	.is_valid_access = tp_prog_is_valid_access,

};



const struct bpf_prog_ops tracepoint_prog_ops = {

};



static bool pe_prog_is_valid_access(int off, int size, enum bpf_access_type type,

				    struct bpf_insn_access_aux *info)

{
@@ -779,7 +791,7 @@ static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, 
}



const struct bpf_verifier_ops perf_event_verifier_ops = {

	.get_func_proto		= tp_prog_func_proto,

	.get_func_proto		= pe_prog_func_proto,

	.is_valid_access	= pe_prog_is_valid_access,

	.convert_ctx_access	= pe_prog_convert_ctx_access,

};

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