[RFC,1/2] trace: Introduce helpers to safely handle dynamic-sized sockaddrs

Commit Message

Chuck Lever Jan. 11, 2022, 6:59 p.m. UTC

Enable a struct sockaddr to be stored in a trace record as a
dynamically-sized field. The common cases are AF_INET and AF_INET6
which are different sizes, and are vastly smaller than a struct
sockaddr_storage.

These are safer because, when used properly, the size of the
sockaddr destination field in each trace record is now guaranteed
to be the same as the source address that is being copied into it.

Link: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Chuck Lever <[e-mail]>
---
 include/trace/bpf_probe.h    |    3 +++
 include/trace/perf.h         |    3 +++
 include/trace/trace_events.h |   18 ++++++++++++++++++
 3 files changed, 24 insertions(+)

Comments

Steven Rostedt Jan. 13, 2022, 5:24 p.m. UTC | #1

On Tue, 11 Jan 2022 13:59:27 -0500
Chuck Lever <[e-mail]> wrote:

> Enable a struct sockaddr to be stored in a trace record as a
> dynamically-sized field. The common cases are AF_INET and AF_INET6
> which are different sizes, and are vastly smaller than a struct
> sockaddr_storage.
> 
> These are safer because, when used properly, the size of the
> sockaddr destination field in each trace record is now guaranteed
> to be the same as the source address that is being copied into it.
> 
> Link: https://lore.kernel.org/all/[e-mail]/
> Signed-off-by: Chuck Lever <[e-mail]>
> ---

This looks fine to me. The only comment I have is that the subject should
be "tracing: ..." not "trace: ..." as "tracing" is what we use for the
tracing subsystem.

I'll test this out if I get time.

-- Steve

Chuck Lever Jan. 13, 2022, 6:13 p.m. UTC | #2

> On Jan 13, 2022, at 12:24 PM, Steven Rostedt <[e-mail]> wrote:
> 
> On Tue, 11 Jan 2022 13:59:27 -0500
> Chuck Lever <[e-mail]> wrote:
> 
>> Enable a struct sockaddr to be stored in a trace record as a
>> dynamically-sized field. The common cases are AF_INET and AF_INET6
>> which are different sizes, and are vastly smaller than a struct
>> sockaddr_storage.
>> 
>> These are safer because, when used properly, the size of the
>> sockaddr destination field in each trace record is now guaranteed
>> to be the same as the source address that is being copied into it.
>> 
>> Link: https://lore.kernel.org/all/[e-mail]/
>> Signed-off-by: Chuck Lever <[e-mail]>
>> ---
> 
> This looks fine to me. The only comment I have is that the subject should
> be "tracing: ..." not "trace: ..." as "tracing" is what we use for the
> tracing subsystem.

Will fix.


> I'll test this out if I get time.

No hurry on my part.


--
Chuck Lever

Patch

diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h
index a8e97f84b652..74068d7b3103 100644
--- a/include/trace/bpf_probe.h
+++ b/include/trace/bpf_probe.h
@@ -21,6 +21,9 @@ 
 #undef __get_bitmask
 #define __get_bitmask(field) (char *)__get_dynamic_array(field)
 
+#undef __get_sockaddr
+#define __get_sockaddr(field) ((struct sockaddr *)__get_dynamic_array(field))
+
 #undef __perf_count
 #define __perf_count(c)	(c)
 
diff --git a/include/trace/perf.h b/include/trace/perf.h
index dbc6c74defc3..953ff4a25691 100644
--- a/include/trace/perf.h
+++ b/include/trace/perf.h
@@ -21,6 +21,9 @@ 
 #undef __get_bitmask
 #define __get_bitmask(field) (char *)__get_dynamic_array(field)
 
+#undef __get_sockaddr
+#define __get_sockaddr(field) ((struct sockaddr *)__get_dynamic_array(field))
+
 #undef __perf_count
 #define __perf_count(c)	(__count = (c))
 
diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index 08810a463880..003104159087 100644
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -108,6 +108,9 @@  TRACE_MAKE_SYSTEM_STR();
 #undef __bitmask
 #define __bitmask(item, nr_bits) __dynamic_array(char, item, -1)
 
+#undef __sockaddr
+#define __sockaddr(field, len) __dynamic_array(u8, field, len)
+
 #undef TP_STRUCT__entry
 #define TP_STRUCT__entry(args...) args
 
@@ -206,6 +209,9 @@  TRACE_MAKE_SYSTEM_STR();
 #undef __bitmask
 #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1)
 
+#undef __sockaddr
+#define __sockaddr(field, len) __dynamic_array(u8, field, len)
+
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)	\
 	struct trace_event_data_offsets_##call {			\
@@ -302,6 +308,9 @@  TRACE_MAKE_SYSTEM_STR();
 		trace_print_bitmask_seq(p, __bitmask, __bitmask_size);	\
 	})
 
+#undef __get_sockaddr
+#define __get_sockaddr(field)	((struct sockaddr *)__get_dynamic_array(field))
+
 #undef __print_flags
 #define __print_flags(flag, delim, flag_array...)			\
 	({								\
@@ -471,6 +480,9 @@  static struct trace_event_functions trace_event_type_funcs_##call = {	\
 #undef __bitmask
 #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1)
 
+#undef __sockaddr
+#define __sockaddr(field, len) __dynamic_array(u8, field, len)
+
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, func, print)	\
 static struct trace_event_fields trace_event_fields_##call[] = {	\
@@ -542,6 +554,9 @@  static struct trace_event_fields trace_event_fields_##call[] = {	\
 #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item,	\
 					 __bitmask_size_in_longs(nr_bits))
 
+#undef __sockaddr
+#define __sockaddr(field, len) __dynamic_array(u8, field, len)
+
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)	\
 static inline notrace int trace_event_get_offsets_##call(		\
@@ -706,6 +721,9 @@  static inline notrace int trace_event_get_offsets_##call(		\
 #define __assign_bitmask(dst, src, nr_bits)					\
 	memcpy(__get_bitmask(dst), (src), __bitmask_size_in_bytes(nr_bits))
 
+#define __assign_sockaddr(dest, src, len)					\
+	memcpy(__get_dynamic_array(dest), src, len)
+
 #undef TP_fast_assign
 #define TP_fast_assign(args...) args