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  3. [PATCH net-next v3 0/3] vsock/test: Improve transport_uaf test
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[PATCH net-next v3 2/3] vsock/test: Introduce get_transports()

Michal Luczaj posted 3 patches 4 months ago
[PATCH net-next v3 2/3] vsock/test: Introduce get_transports()
Posted by Michal Luczaj 4 months ago 
Return a bitmap of registered vsock transports. As guesstimated by grepping
/proc/kallsyms (CONFIG_KALLSYMS=y) for known symbols of type `struct
vsock_transport`, or `struct virtio_transport` in case the vsock_transport
is embedded within.

Note that the way `enum transport` and `transport_ksyms[]` are defined
triggers checkpatch.pl:

util.h:11: ERROR: Macros with complex values should be enclosed in parentheses
util.h:20: ERROR: Macros with complex values should be enclosed in parentheses
util.h:20: WARNING: Argument 'symbol' is not used in function-like macro
util.h:28: WARNING: Argument 'name' is not used in function-like macro

While commit 15d4734c7a58 ("checkpatch: qualify do-while-0 advice")
suggests it is known that the ERRORs heuristics are insufficient, I can not
find many other places where preprocessor is used in this
checkpatch-unhappy fashion. Notable exception being bcachefs, e.g.
fs/bcachefs/alloc_background_format.h. WARNINGs regarding unused macro
arguments seem more common, e.g. __ASM_SEL in arch/x86/include/asm/asm.h.

In other words, this might be unnecessarily complex. The same can be
achieved by just telling human to keep the order:

enum transport {
	TRANSPORT_LOOPBACK = BIT(0),
	TRANSPORT_VIRTIO = BIT(1),
	TRANSPORT_VHOST = BIT(2),
	TRANSPORT_VMCI = BIT(3),
	TRANSPORT_HYPERV = BIT(4),
	TRANSPORT_NUM = 5,
};

 #define KSYM_ENTRY(sym) "d " sym "_transport"

/* Keep `enum transport` order */
static const char * const transport_ksyms[] = {
	KSYM_ENTRY("loopback"),
	KSYM_ENTRY("virtio"),
	KSYM_ENTRY("vhost"),
	KSYM_ENTRY("vmci"),
	KSYM_ENTRY("vhs"),
};

Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 tools/testing/vsock/util.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
 tools/testing/vsock/util.h | 29 ++++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
index b7b3fb2221c1682ecde58cf12e2f0b0ded1cff39..803f1e075b62228c25f9dffa1eff131b8072a06a 100644
--- a/tools/testing/vsock/util.c
+++ b/tools/testing/vsock/util.c
@@ -7,6 +7,7 @@
  * Author: Stefan Hajnoczi <stefanha@redhat.com>
  */
 
+#include <ctype.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdint.h>
@@ -23,6 +24,9 @@
 #include "control.h"
 #include "util.h"
 
+#define KALLSYMS_PATH		"/proc/kallsyms"
+#define KALLSYMS_LINE_LEN	512
+
 /* Install signal handlers */
 void init_signals(void)
 {
@@ -854,3 +858,55 @@ void enable_so_linger(int fd, int timeout)
 		exit(EXIT_FAILURE);
 	}
 }
+
+static int __get_transports(void)
+{
+	char buf[KALLSYMS_LINE_LEN];
+	const char *ksym;
+	int ret = 0;
+	FILE *f;
+
+	f = fopen(KALLSYMS_PATH, "r");
+	if (!f) {
+		perror("Can't open " KALLSYMS_PATH);
+		exit(EXIT_FAILURE);
+	}
+
+	while (fgets(buf, sizeof(buf), f)) {
+		char *match;
+		int i;
+
+		assert(buf[strlen(buf) - 1] == '\n');
+
+		for (i = 0; i < TRANSPORT_NUM; ++i) {
+			if (ret & BIT(i))
+				continue;
+
+			/* Match should be followed by '\t' or '\n'.
+			 * See kallsyms.c:s_show().
+			 */
+			ksym = transport_ksyms[i];
+			match = strstr(buf, ksym);
+			if (match && isspace(match[strlen(ksym)])) {
+				ret |= BIT(i);
+				break;
+			}
+		}
+	}
+
+	fclose(f);
+	return ret;
+}
+
+/* Return integer with TRANSPORT_* bit set for every (known) registered vsock
+ * transport.
+ */
+int get_transports(void)
+{
+	static int tr = -1;
+
+	if (tr == -1)
+		tr = __get_transports();
+
+	return tr;
+}
diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
index 0afe7cbae12e5194172c639ccfbeb8b81f7c25ac..71895192cc02313bf52784e2f77aa3b0c28a0c94 100644
--- a/tools/testing/vsock/util.h
+++ b/tools/testing/vsock/util.h
@@ -3,8 +3,36 @@
 #define UTIL_H
 
 #include <sys/socket.h>
+#include <linux/bitops.h>
+#include <linux/kernel.h>
 #include <linux/vm_sockets.h>
 
+/* All known vsock transports, see callers of vsock_core_register() */
+#define KNOWN_TRANSPORTS(x)		\
+	x(LOOPBACK, "loopback")		\
+	x(VIRTIO, "virtio")		\
+	x(VHOST, "vhost")		\
+	x(VMCI, "vmci")			\
+	x(HYPERV, "hvs")
+
+enum transport {
+	TRANSPORT_COUNTER_BASE = __COUNTER__ + 1,
+	#define x(name, symbol)		\
+		TRANSPORT_##name = BIT(__COUNTER__ - TRANSPORT_COUNTER_BASE),
+	KNOWN_TRANSPORTS(x)
+	TRANSPORT_NUM = __COUNTER__ - TRANSPORT_COUNTER_BASE,
+	#undef x
+};
+
+static const char * const transport_ksyms[] = {
+	#define x(name, symbol) "d " symbol "_transport",
+	KNOWN_TRANSPORTS(x)
+	#undef x
+};
+
+static_assert(ARRAY_SIZE(transport_ksyms) == TRANSPORT_NUM);
+static_assert(BITS_PER_TYPE(int) >= TRANSPORT_NUM);
+
 /* Tests can either run as the client or the server */
 enum test_mode {
 	TEST_MODE_UNSET,
@@ -82,4 +110,5 @@ void setsockopt_timeval_check(int fd, int level, int optname,
 			      struct timeval val, char const *errmsg);
 void enable_so_zerocopy_check(int fd);
 void enable_so_linger(int fd, int timeout);
+int get_transports(void);
 #endif /* UTIL_H */

-- 
2.49.0
Re: [PATCH net-next v3 2/3] vsock/test: Introduce get_transports()
Posted by Stefano Garzarella 3 months, 3 weeks ago 
On Wed, Jun 11, 2025 at 09:56:51PM +0200, Michal Luczaj wrote:
>Return a bitmap of registered vsock transports. As guesstimated by grepping
>/proc/kallsyms (CONFIG_KALLSYMS=y) for known symbols of type `struct
>vsock_transport`, or `struct virtio_transport` in case the vsock_transport
>is embedded within.
>
>Note that the way `enum transport` and `transport_ksyms[]` are defined
>triggers checkpatch.pl:
>
>util.h:11: ERROR: Macros with complex values should be enclosed in parentheses
>util.h:20: ERROR: Macros with complex values should be enclosed in parentheses
>util.h:20: WARNING: Argument 'symbol' is not used in function-like macro
>util.h:28: WARNING: Argument 'name' is not used in function-like macro
>
>While commit 15d4734c7a58 ("checkpatch: qualify do-while-0 advice")
>suggests it is known that the ERRORs heuristics are insufficient, I can not
>find many other places where preprocessor is used in this
>checkpatch-unhappy fashion. Notable exception being bcachefs, e.g.
>fs/bcachefs/alloc_background_format.h. WARNINGs regarding unused macro
>arguments seem more common, e.g. __ASM_SEL in arch/x86/include/asm/asm.h.
>
>In other words, this might be unnecessarily complex. The same can be
>achieved by just telling human to keep the order:
>
>enum transport {
>	TRANSPORT_LOOPBACK = BIT(0),
>	TRANSPORT_VIRTIO = BIT(1),
>	TRANSPORT_VHOST = BIT(2),
>	TRANSPORT_VMCI = BIT(3),
>	TRANSPORT_HYPERV = BIT(4),
>	TRANSPORT_NUM = 5,
>};
>
> #define KSYM_ENTRY(sym) "d " sym "_transport"
>
>/* Keep `enum transport` order */
>static const char * const transport_ksyms[] = {
>	KSYM_ENTRY("loopback"),
>	KSYM_ENTRY("virtio"),
>	KSYM_ENTRY("vhost"),
>	KSYM_ENTRY("vmci"),
>	KSYM_ENTRY("vhs"),
>};
>
>Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
>Signed-off-by: Michal Luczaj <mhal@rbox.co>
>---
> tools/testing/vsock/util.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
> tools/testing/vsock/util.h | 29 ++++++++++++++++++++++++
> 2 files changed, 85 insertions(+)

LGTM!

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
>index b7b3fb2221c1682ecde58cf12e2f0b0ded1cff39..803f1e075b62228c25f9dffa1eff131b8072a06a 100644
>--- a/tools/testing/vsock/util.c
>+++ b/tools/testing/vsock/util.c
>@@ -7,6 +7,7 @@
>  * Author: Stefan Hajnoczi <stefanha@redhat.com>
>  */
>
>+#include <ctype.h>
> #include <errno.h>
> #include <stdio.h>
> #include <stdint.h>
>@@ -23,6 +24,9 @@
> #include "control.h"
> #include "util.h"
>
>+#define KALLSYMS_PATH		"/proc/kallsyms"
>+#define KALLSYMS_LINE_LEN	512
>+
> /* Install signal handlers */
> void init_signals(void)
> {
>@@ -854,3 +858,55 @@ void enable_so_linger(int fd, int timeout)
> 		exit(EXIT_FAILURE);
> 	}
> }
>+
>+static int __get_transports(void)
>+{
>+	char buf[KALLSYMS_LINE_LEN];
>+	const char *ksym;
>+	int ret = 0;
>+	FILE *f;
>+
>+	f = fopen(KALLSYMS_PATH, "r");
>+	if (!f) {
>+		perror("Can't open " KALLSYMS_PATH);
>+		exit(EXIT_FAILURE);
>+	}
>+
>+	while (fgets(buf, sizeof(buf), f)) {
>+		char *match;
>+		int i;
>+
>+		assert(buf[strlen(buf) - 1] == '\n');
>+
>+		for (i = 0; i < TRANSPORT_NUM; ++i) {
>+			if (ret & BIT(i))
>+				continue;
>+
>+			/* Match should be followed by '\t' or '\n'.
>+			 * See kallsyms.c:s_show().
>+			 */
>+			ksym = transport_ksyms[i];
>+			match = strstr(buf, ksym);
>+			if (match && isspace(match[strlen(ksym)])) {
>+				ret |= BIT(i);
>+				break;
>+			}
>+		}
>+	}
>+
>+	fclose(f);
>+	return ret;
>+}
>+
>+/* Return integer with TRANSPORT_* bit set for every (known) registered vsock
>+ * transport.
>+ */
>+int get_transports(void)
>+{
>+	static int tr = -1;
>+
>+	if (tr == -1)
>+		tr = __get_transports();
>+
>+	return tr;
>+}
>diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
>index 0afe7cbae12e5194172c639ccfbeb8b81f7c25ac..71895192cc02313bf52784e2f77aa3b0c28a0c94 100644
>--- a/tools/testing/vsock/util.h
>+++ b/tools/testing/vsock/util.h
>@@ -3,8 +3,36 @@
> #define UTIL_H
>
> #include <sys/socket.h>
>+#include <linux/bitops.h>
>+#include <linux/kernel.h>
> #include <linux/vm_sockets.h>
>
>+/* All known vsock transports, see callers of vsock_core_register() */
>+#define KNOWN_TRANSPORTS(x)		\
>+	x(LOOPBACK, "loopback")		\
>+	x(VIRTIO, "virtio")		\
>+	x(VHOST, "vhost")		\
>+	x(VMCI, "vmci")			\
>+	x(HYPERV, "hvs")
>+
>+enum transport {
>+	TRANSPORT_COUNTER_BASE = __COUNTER__ + 1,
>+	#define x(name, symbol)		\
>+		TRANSPORT_##name = BIT(__COUNTER__ - TRANSPORT_COUNTER_BASE),
>+	KNOWN_TRANSPORTS(x)
>+	TRANSPORT_NUM = __COUNTER__ - TRANSPORT_COUNTER_BASE,
>+	#undef x
>+};
>+
>+static const char * const transport_ksyms[] = {
>+	#define x(name, symbol) "d " symbol "_transport",
>+	KNOWN_TRANSPORTS(x)
>+	#undef x
>+};
>+
>+static_assert(ARRAY_SIZE(transport_ksyms) == TRANSPORT_NUM);
>+static_assert(BITS_PER_TYPE(int) >= TRANSPORT_NUM);
>+
> /* Tests can either run as the client or the server */
> enum test_mode {
> 	TEST_MODE_UNSET,
>@@ -82,4 +110,5 @@ void setsockopt_timeval_check(int fd, int level, int optname,
> 			      struct timeval val, char const *errmsg);
> void enable_so_zerocopy_check(int fd);
> void enable_so_linger(int fd, int timeout);
>+int get_transports(void);
> #endif /* UTIL_H */
>
>-- 
>2.49.0
>
Re: [PATCH net-next v3 2/3] vsock/test: Introduce get_transports()
Posted by Luigi Leonardi 3 months, 4 weeks ago 
Hi Michal,

On Wed, Jun 11, 2025 at 09:56:51PM +0200, Michal Luczaj wrote:
>Return a bitmap of registered vsock transports. As guesstimated by 
>grepping
>/proc/kallsyms (CONFIG_KALLSYMS=y) for known symbols of type `struct
>vsock_transport`, or `struct virtio_transport` in case the 
>vsock_transport
>is embedded within.
>
>Note that the way `enum transport` and `transport_ksyms[]` are defined
>triggers checkpatch.pl:
>
>util.h:11: ERROR: Macros with complex values should be enclosed in 
>parentheses
>util.h:20: ERROR: Macros with complex values should be enclosed in 
>parentheses
>util.h:20: WARNING: Argument 'symbol' is not used in function-like 
>macro
>util.h:28: WARNING: Argument 'name' is not used in function-like macro
>
>While commit 15d4734c7a58 ("checkpatch: qualify do-while-0 advice")
>suggests it is known that the ERRORs heuristics are insufficient, I can 
>not
>find many other places where preprocessor is used in this
>checkpatch-unhappy fashion. Notable exception being bcachefs, e.g.
>fs/bcachefs/alloc_background_format.h. WARNINGs regarding unused macro
>arguments seem more common, e.g. __ASM_SEL in 
>arch/x86/include/asm/asm.h.
>
>In other words, this might be unnecessarily complex. The same can be
>achieved by just telling human to keep the order:
>
>enum transport {
>	TRANSPORT_LOOPBACK = BIT(0),
>	TRANSPORT_VIRTIO = BIT(1),
>	TRANSPORT_VHOST = BIT(2),
>	TRANSPORT_VMCI = BIT(3),
>	TRANSPORT_HYPERV = BIT(4),
>	TRANSPORT_NUM = 5,
>};
>
> #define KSYM_ENTRY(sym) "d " sym "_transport"
>
>/* Keep `enum transport` order */
>static const char * const transport_ksyms[] = {
>	KSYM_ENTRY("loopback"),
>	KSYM_ENTRY("virtio"),
>	KSYM_ENTRY("vhost"),
>	KSYM_ENTRY("vmci"),
>	KSYM_ENTRY("vhs"),
>};
>
>Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
>Signed-off-by: Michal Luczaj <mhal@rbox.co>
>---
> tools/testing/vsock/util.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
> tools/testing/vsock/util.h | 29 ++++++++++++++++++++++++
> 2 files changed, 85 insertions(+)
>
>diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
>index b7b3fb2221c1682ecde58cf12e2f0b0ded1cff39..803f1e075b62228c25f9dffa1eff131b8072a06a 100644
>--- a/tools/testing/vsock/util.c
>+++ b/tools/testing/vsock/util.c
>@@ -7,6 +7,7 @@
>  * Author: Stefan Hajnoczi <stefanha@redhat.com>
>  */
>
>+#include <ctype.h>
> #include <errno.h>
> #include <stdio.h>
> #include <stdint.h>
>@@ -23,6 +24,9 @@
> #include "control.h"
> #include "util.h"
>
>+#define KALLSYMS_PATH		"/proc/kallsyms"
>+#define KALLSYMS_LINE_LEN	512
>+
> /* Install signal handlers */
> void init_signals(void)
> {
>@@ -854,3 +858,55 @@ void enable_so_linger(int fd, int timeout)
> 		exit(EXIT_FAILURE);
> 	}
> }
>+
>+static int __get_transports(void)
>+{
>+	char buf[KALLSYMS_LINE_LEN];
>+	const char *ksym;
>+	int ret = 0;
>+	FILE *f;
>+
>+	f = fopen(KALLSYMS_PATH, "r");
>+	if (!f) {
>+		perror("Can't open " KALLSYMS_PATH);
>+		exit(EXIT_FAILURE);
>+	}
>+
>+	while (fgets(buf, sizeof(buf), f)) {
>+		char *match;
>+		int i;
>+
>+		assert(buf[strlen(buf) - 1] == '\n');
>+
>+		for (i = 0; i < TRANSPORT_NUM; ++i) {
>+			if (ret & BIT(i))
>+				continue;
>+
>+			/* Match should be followed by '\t' or '\n'.
>+			 * See kallsyms.c:s_show().
>+			 */
>+			ksym = transport_ksyms[i];
>+			match = strstr(buf, ksym);
>+			if (match && isspace(match[strlen(ksym)])) {
>+				ret |= BIT(i);
>+				break;
>+			}
>+		}
>+	}
>+
>+	fclose(f);
>+	return ret;
>+}
>+
>+/* Return integer with TRANSPORT_* bit set for every (known) registered vsock
>+ * transport.
>+ */
>+int get_transports(void)
>+{
>+	static int tr = -1;
>+
>+	if (tr == -1)
>+		tr = __get_transports();
>+
>+	return tr;
>+}
>diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
>index 0afe7cbae12e5194172c639ccfbeb8b81f7c25ac..71895192cc02313bf52784e2f77aa3b0c28a0c94 100644
>--- a/tools/testing/vsock/util.h
>+++ b/tools/testing/vsock/util.h
>@@ -3,8 +3,36 @@
> #define UTIL_H
>
> #include <sys/socket.h>
>+#include <linux/bitops.h>
>+#include <linux/kernel.h>
> #include <linux/vm_sockets.h>
>
>+/* All known vsock transports, see callers of vsock_core_register() */
>+#define KNOWN_TRANSPORTS(x)		\
>+	x(LOOPBACK, "loopback")		\
>+	x(VIRTIO, "virtio")		\
>+	x(VHOST, "vhost")		\
>+	x(VMCI, "vmci")			\
>+	x(HYPERV, "hvs")
>+
>+enum transport {
>+	TRANSPORT_COUNTER_BASE = __COUNTER__ + 1,
>+	#define x(name, symbol)		\
>+		TRANSPORT_##name = BIT(__COUNTER__ - TRANSPORT_COUNTER_BASE),
>+	KNOWN_TRANSPORTS(x)
>+	TRANSPORT_NUM = __COUNTER__ - TRANSPORT_COUNTER_BASE,
>+	#undef x
>+};
>+
>+static const char * const transport_ksyms[] = {
>+	#define x(name, symbol) "d " symbol "_transport",
>+	KNOWN_TRANSPORTS(x)
>+	#undef x
>+};
>+
>+static_assert(ARRAY_SIZE(transport_ksyms) == TRANSPORT_NUM);
>+static_assert(BITS_PER_TYPE(int) >= TRANSPORT_NUM);
>+
> /* Tests can either run as the client or the server */
> enum test_mode {
> 	TEST_MODE_UNSET,
>@@ -82,4 +110,5 @@ void setsockopt_timeval_check(int fd, int level, int optname,
> 			      struct timeval val, char const *errmsg);
> void enable_so_zerocopy_check(int fd);
> void enable_so_linger(int fd, int timeout);
>+int get_transports(void);
> #endif /* UTIL_H */
>
>-- 
>2.49.0
>

Checked the code and tested `get_transports()`. It works as expected!
I'm not sure about the `checkpatch.pl` errors, but code LGTM to me.

Tested-by: Luigi Leonardi <leonardi@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>

Thanks!
Luigi

Patchew 2.1-devel-b67e4c2

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