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Subject[PATCH 4.15 096/105] trace/bpf: remove helper bpf_perf_prog_read_value from tracepoint type programs
Date
4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Yonghong Song <yhs@fb.com>

commit f005afede992e265bb98534b86912bb669ccd0d2 upstream.

Commit 4bebdc7a85aa ("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: 4bebdc7a85aa ("bpf: add helper bpf_perf_prog_read_value")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/trace/bpf_trace.c | 68 +++++++++++++++++++++++++++--------------------
1 file changed, 40 insertions(+), 28 deletions(-)

--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -636,7 +636,41 @@ static const struct bpf_func_proto bpf_g
.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;
@@ -653,8 +687,8 @@ 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,
@@ -662,7 +696,7 @@ static const struct bpf_func_proto bpf_p
.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:
@@ -670,34 +704,12 @@ static const struct bpf_func_proto *tp_p
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)
{
@@ -754,7 +766,7 @@ static u32 pe_prog_convert_ctx_access(en
}

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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