[PATCH v2] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl

[PATCH v2] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl

[luca.boccassi]

From: Luca Boccassi <luca.boccassi@gmail.com>

Userspace when requesting a session via the ioctl specifies a name and
gets a FD, but then there is no ioctl to go back the other way and get
the name given a LUO session FD. This is problematic especially when
there is a userspace orchestrator that wants to check what FDs it is
handling for clients without having to do manual string scraping of
procfs, or without procfs at all.

Add a ioctl to simply get the name from an FD.

Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
---
v2: adjusted the commit message a bit and rebased on liveupdate/next

 include/uapi/linux/liveupdate.h               | 19 +++++
 kernel/liveupdate/luo_session.c               | 13 ++++
 .../testing/selftests/liveupdate/liveupdate.c | 71 +++++++++++++++++++
 3 files changed, 103 insertions(+)

diff --git a/include/uapi/linux/liveupdate.h b/include/uapi/linux/liveupdate.h
index 30bc66ee9436a..41dc44d239dde 100644
--- a/include/uapi/linux/liveupdate.h
+++ b/include/uapi/linux/liveupdate.h
@@ -59,6 +59,7 @@ enum {
 	LIVEUPDATE_CMD_SESSION_PRESERVE_FD = LIVEUPDATE_CMD_SESSION_BASE,
 	LIVEUPDATE_CMD_SESSION_RETRIEVE_FD = 0x41,
 	LIVEUPDATE_CMD_SESSION_FINISH = 0x42,
+	LIVEUPDATE_CMD_SESSION_GET_NAME = 0x43,
 };
 
 /**
@@ -213,4 +214,22 @@ struct liveupdate_session_finish {
 #define LIVEUPDATE_SESSION_FINISH					\
 	_IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_FINISH)
 
+/**
+ * struct liveupdate_session_get_name - ioctl(LIVEUPDATE_SESSION_GET_NAME)
+ * @size:  Input; sizeof(struct liveupdate_session_get_name)
+ * @name:  Output; A null-terminated string with the full session name.
+ *
+ * Retrieves the full name of the session associated with this file descriptor.
+ * This is useful because the kernel may truncate the name shown in /proc.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+struct liveupdate_session_get_name {
+	__u32		size;
+	__u8		name[LIVEUPDATE_SESSION_NAME_LENGTH];
+};
+
+#define LIVEUPDATE_SESSION_GET_NAME					\
+	_IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_GET_NAME)
+
 #endif /* _UAPI_LIVEUPDATE_H */
diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c
index 25ae704d77873..af9e498206d24 100644
--- a/kernel/liveupdate/luo_session.c
+++ b/kernel/liveupdate/luo_session.c
@@ -289,10 +289,21 @@ static int luo_session_finish(struct luo_session *session,
 	return luo_ucmd_respond(ucmd, sizeof(*argp));
 }
 
+static int luo_session_get_name(struct luo_session *session,
+				struct luo_ucmd *ucmd)
+{
+	struct liveupdate_session_get_name *argp = ucmd->cmd;
+
+	strscpy((char *)argp->name, session->name, sizeof(argp->name));
+
+	return luo_ucmd_respond(ucmd, sizeof(*argp));
+}
+
 union ucmd_buffer {
 	struct liveupdate_session_finish finish;
 	struct liveupdate_session_preserve_fd preserve;
 	struct liveupdate_session_retrieve_fd retrieve;
+	struct liveupdate_session_get_name get_name;
 };
 
 struct luo_ioctl_op {
@@ -319,6 +330,8 @@ static const struct luo_ioctl_op luo_session_ioctl_ops[] = {
 		 struct liveupdate_session_preserve_fd, token),
 	IOCTL_OP(LIVEUPDATE_SESSION_RETRIEVE_FD, luo_session_retrieve_fd,
 		 struct liveupdate_session_retrieve_fd, token),
+	IOCTL_OP(LIVEUPDATE_SESSION_GET_NAME, luo_session_get_name,
+		 struct liveupdate_session_get_name, name),
 };
 
 static long luo_session_ioctl(struct file *filep, unsigned int cmd,
diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
index c2878e3d5ef90..bdc1cedc4f944 100644
--- a/tools/testing/selftests/liveupdate/liveupdate.c
+++ b/tools/testing/selftests/liveupdate/liveupdate.c
@@ -102,6 +102,22 @@ static int create_session(int lu_fd, const char *name)
 	return args.fd;
 }
 
+/* Helper function to get a session name via ioctl. */
+static int get_session_name(int session_fd, char *name, size_t name_len)
+{
+	struct liveupdate_session_get_name args = {};
+
+	args.size = sizeof(args);
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_GET_NAME, &args))
+		return -errno;
+
+	strncpy(name, (char *)args.name, name_len - 1);
+	name[name_len - 1] = '\0';
+
+	return 0;
+}
+
 /*
  * Test Case: Create Duplicate Session
  *
@@ -345,4 +361,59 @@ TEST_F(liveupdate_device, preserve_unsupported_fd)
 	ASSERT_EQ(close(session_fd), 0);
 }
 
+/*
+ * Test Case: Get Session Name
+ *
+ * Verifies that the full session name can be retrieved from a session file
+ * descriptor via ioctl.
+ */
+TEST_F(liveupdate_device, get_session_name)
+{
+	char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
+	const char *session_name = "get-name-test-session";
+	int session_fd;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, session_name);
+	ASSERT_GE(session_fd, 0);
+
+	ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
+	ASSERT_STREQ(name_buf, session_name);
+
+	ASSERT_EQ(close(session_fd), 0);
+}
+
+/*
+ * Test Case: Get Session Name at Maximum Length
+ *
+ * Verifies that a session name using the full LIVEUPDATE_SESSION_NAME_LENGTH
+ * (minus the null terminator) can be correctly retrieved.
+ */
+TEST_F(liveupdate_device, get_session_name_max_length)
+{
+	char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
+	char long_name[LIVEUPDATE_SESSION_NAME_LENGTH];
+	int session_fd;
+
+	memset(long_name, 'A', sizeof(long_name) - 1);
+	long_name[sizeof(long_name) - 1] = '\0';
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, long_name);
+	ASSERT_GE(session_fd, 0);
+
+	ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
+	ASSERT_STREQ(name_buf, long_name);
+
+	ASSERT_EQ(close(session_fd), 0);
+}
+
 TEST_HARNESS_MAIN
-- 
2.47.3

[PATCH v2] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl

[luca.boccassi]

From: Luca Boccassi <luca.boccassi@gmail.com>

Userspace when requesting a session via the ioctl specifies a name and
gets a FD, but then there is no ioctl to go back the other way and get
the name given a LUO session FD. This is problematic especially when
there is a userspace orchestrator that wants to check what FDs it is
handling for clients without having to do manual string scraping of
procfs, or without procfs at all.

Add a ioctl to simply get the name from an FD.

Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
---
This was requested by Lennart and Christian when discussing integration
with systemd for LUO management.

v2: apply one fix from bot review about cleanup on error path:
    https://sashiko.dev/#/patchset/20260415184536.1155220-1-luca.boccassi%40gmail.com
    the other comments are invalid: luo is not a kmod, and the write hooks are not set up

 include/uapi/linux/liveupdate.h               | 19 +++++
 kernel/liveupdate/luo_session.c               | 13 ++++
 .../testing/selftests/liveupdate/liveupdate.c | 71 +++++++++++++++++++
 3 files changed, 103 insertions(+)

diff --git a/include/uapi/linux/liveupdate.h b/include/uapi/linux/liveupdate.h
index 30bc66ee9436a..41dc44d239dde 100644
--- a/include/uapi/linux/liveupdate.h
+++ b/include/uapi/linux/liveupdate.h
@@ -59,6 +59,7 @@ enum {
 	LIVEUPDATE_CMD_SESSION_PRESERVE_FD = LIVEUPDATE_CMD_SESSION_BASE,
 	LIVEUPDATE_CMD_SESSION_RETRIEVE_FD = 0x41,
 	LIVEUPDATE_CMD_SESSION_FINISH = 0x42,
+	LIVEUPDATE_CMD_SESSION_GET_NAME = 0x43,
 };
 
 /**
@@ -213,4 +214,22 @@ struct liveupdate_session_finish {
 #define LIVEUPDATE_SESSION_FINISH					\
 	_IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_FINISH)
 
+/**
+ * struct liveupdate_session_get_name - ioctl(LIVEUPDATE_SESSION_GET_NAME)
+ * @size:  Input; sizeof(struct liveupdate_session_get_name)
+ * @name:  Output; A null-terminated string with the full session name.
+ *
+ * Retrieves the full name of the session associated with this file descriptor.
+ * This is useful because the kernel may truncate the name shown in /proc.
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+struct liveupdate_session_get_name {
+	__u32		size;
+	__u8		name[LIVEUPDATE_SESSION_NAME_LENGTH];
+};
+
+#define LIVEUPDATE_SESSION_GET_NAME					\
+	_IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_GET_NAME)
+
 #endif /* _UAPI_LIVEUPDATE_H */
diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c
index 25ae704d77873..af9e498206d24 100644
--- a/kernel/liveupdate/luo_session.c
+++ b/kernel/liveupdate/luo_session.c
@@ -289,10 +289,21 @@ static int luo_session_finish(struct luo_session *session,
 	return luo_ucmd_respond(ucmd, sizeof(*argp));
 }
 
+static int luo_session_get_name(struct luo_session *session,
+				struct luo_ucmd *ucmd)
+{
+	struct liveupdate_session_get_name *argp = ucmd->cmd;
+
+	strscpy((char *)argp->name, session->name, sizeof(argp->name));
+
+	return luo_ucmd_respond(ucmd, sizeof(*argp));
+}
+
 union ucmd_buffer {
 	struct liveupdate_session_finish finish;
 	struct liveupdate_session_preserve_fd preserve;
 	struct liveupdate_session_retrieve_fd retrieve;
+	struct liveupdate_session_get_name get_name;
 };
 
 struct luo_ioctl_op {
@@ -319,6 +330,8 @@ static const struct luo_ioctl_op luo_session_ioctl_ops[] = {
 		 struct liveupdate_session_preserve_fd, token),
 	IOCTL_OP(LIVEUPDATE_SESSION_RETRIEVE_FD, luo_session_retrieve_fd,
 		 struct liveupdate_session_retrieve_fd, token),
+	IOCTL_OP(LIVEUPDATE_SESSION_GET_NAME, luo_session_get_name,
+		 struct liveupdate_session_get_name, name),
 };
 
 static long luo_session_ioctl(struct file *filep, unsigned int cmd,
diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
index c2878e3d5ef90..bdc1cedc4f944 100644
--- a/tools/testing/selftests/liveupdate/liveupdate.c
+++ b/tools/testing/selftests/liveupdate/liveupdate.c
@@ -102,6 +102,22 @@ static int create_session(int lu_fd, const char *name)
 	return args.fd;
 }
 
+/* Helper function to get a session name via ioctl. */
+static int get_session_name(int session_fd, char *name, size_t name_len)
+{
+	struct liveupdate_session_get_name args = {};
+
+	args.size = sizeof(args);
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_GET_NAME, &args))
+		return -errno;
+
+	strncpy(name, (char *)args.name, name_len - 1);
+	name[name_len - 1] = '\0';
+
+	return 0;
+}
+
 /*
  * Test Case: Create Duplicate Session
  *
@@ -345,4 +361,59 @@ TEST_F(liveupdate_device, preserve_unsupported_fd)
 	ASSERT_EQ(close(session_fd), 0);
 }
 
+/*
+ * Test Case: Get Session Name
+ *
+ * Verifies that the full session name can be retrieved from a session file
+ * descriptor via ioctl.
+ */
+TEST_F(liveupdate_device, get_session_name)
+{
+	char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
+	const char *session_name = "get-name-test-session";
+	int session_fd;
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, session_name);
+	ASSERT_GE(session_fd, 0);
+
+	ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
+	ASSERT_STREQ(name_buf, session_name);
+
+	ASSERT_EQ(close(session_fd), 0);
+}
+
+/*
+ * Test Case: Get Session Name at Maximum Length
+ *
+ * Verifies that a session name using the full LIVEUPDATE_SESSION_NAME_LENGTH
+ * (minus the null terminator) can be correctly retrieved.
+ */
+TEST_F(liveupdate_device, get_session_name_max_length)
+{
+	char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
+	char long_name[LIVEUPDATE_SESSION_NAME_LENGTH];
+	int session_fd;
+
+	memset(long_name, 'A', sizeof(long_name) - 1);
+	long_name[sizeof(long_name) - 1] = '\0';
+
+	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
+	if (self->fd1 < 0 && errno == ENOENT)
+		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
+	ASSERT_GE(self->fd1, 0);
+
+	session_fd = create_session(self->fd1, long_name);
+	ASSERT_GE(session_fd, 0);
+
+	ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
+	ASSERT_STREQ(name_buf, long_name);
+
+	ASSERT_EQ(close(session_fd), 0);
+}
+
 TEST_HARNESS_MAIN
-- 
2.47.3

Re: [PATCH v2] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl

[Pasha Tatashin]

On 04-17 01:36, luca.boccassi@gmail.com wrote:
> From: Luca Boccassi <luca.boccassi@gmail.com>
> 
> Userspace when requesting a session via the ioctl specifies a name and
> gets a FD, but then there is no ioctl to go back the other way and get
> the name given a LUO session FD. This is problematic especially when
> there is a userspace orchestrator that wants to check what FDs it is
> handling for clients without having to do manual string scraping of
> procfs, or without procfs at all.
> 
> Add a ioctl to simply get the name from an FD.
> 
> Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
> ---
> This was requested by Lennart and Christian when discussing integration
> with systemd for LUO management.
> 
> v2: apply one fix from bot review about cleanup on error path:
>     https://sashiko.dev/#/patchset/20260415184536.1155220-1-luca.boccassi%40gmail.com
>     the other comments are invalid: luo is not a kmod, and the write hooks are not set up

Please split into two patches, and also CC to kernel-linux.
> 
>  include/uapi/linux/liveupdate.h               | 19 +++++
>  kernel/liveupdate/luo_session.c               | 13 ++++
>  .../testing/selftests/liveupdate/liveupdate.c | 71 +++++++++++++++++++
>  3 files changed, 103 insertions(+)
> 
> diff --git a/include/uapi/linux/liveupdate.h b/include/uapi/linux/liveupdate.h
> index 30bc66ee9436a..41dc44d239dde 100644
> --- a/include/uapi/linux/liveupdate.h
> +++ b/include/uapi/linux/liveupdate.h
> @@ -59,6 +59,7 @@ enum {
>  	LIVEUPDATE_CMD_SESSION_PRESERVE_FD = LIVEUPDATE_CMD_SESSION_BASE,
>  	LIVEUPDATE_CMD_SESSION_RETRIEVE_FD = 0x41,
>  	LIVEUPDATE_CMD_SESSION_FINISH = 0x42,
> +	LIVEUPDATE_CMD_SESSION_GET_NAME = 0x43,
>  };
>  
>  /**
> @@ -213,4 +214,22 @@ struct liveupdate_session_finish {
>  #define LIVEUPDATE_SESSION_FINISH					\
>  	_IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_FINISH)
>  
> +/**
> + * struct liveupdate_session_get_name - ioctl(LIVEUPDATE_SESSION_GET_NAME)
> + * @size:  Input; sizeof(struct liveupdate_session_get_name)
> + * @name:  Output; A null-terminated string with the full session name.
> + *
> + * Retrieves the full name of the session associated with this file descriptor.
> + * This is useful because the kernel may truncate the name shown in /proc.
> + *
> + * Return: 0 on success, negative error code on failure.
> + */
> +struct liveupdate_session_get_name {
> +	__u32		size;
> +	__u8		name[LIVEUPDATE_SESSION_NAME_LENGTH];

Add __u32  reserved;

Thanks,
Pasha


> +};
> +
> +#define LIVEUPDATE_SESSION_GET_NAME					\
> +	_IO(LIVEUPDATE_IOCTL_TYPE, LIVEUPDATE_CMD_SESSION_GET_NAME)
> +
>  #endif /* _UAPI_LIVEUPDATE_H */
> diff --git a/kernel/liveupdate/luo_session.c b/kernel/liveupdate/luo_session.c
> index 25ae704d77873..af9e498206d24 100644
> --- a/kernel/liveupdate/luo_session.c
> +++ b/kernel/liveupdate/luo_session.c
> @@ -289,10 +289,21 @@ static int luo_session_finish(struct luo_session *session,
>  	return luo_ucmd_respond(ucmd, sizeof(*argp));
>  }
>  
> +static int luo_session_get_name(struct luo_session *session,
> +				struct luo_ucmd *ucmd)
> +{
> +	struct liveupdate_session_get_name *argp = ucmd->cmd;
> +
> +	strscpy((char *)argp->name, session->name, sizeof(argp->name));
> +
> +	return luo_ucmd_respond(ucmd, sizeof(*argp));
> +}
> +
>  union ucmd_buffer {
>  	struct liveupdate_session_finish finish;
>  	struct liveupdate_session_preserve_fd preserve;
>  	struct liveupdate_session_retrieve_fd retrieve;
> +	struct liveupdate_session_get_name get_name;
>  };
>  
>  struct luo_ioctl_op {
> @@ -319,6 +330,8 @@ static const struct luo_ioctl_op luo_session_ioctl_ops[] = {
>  		 struct liveupdate_session_preserve_fd, token),
>  	IOCTL_OP(LIVEUPDATE_SESSION_RETRIEVE_FD, luo_session_retrieve_fd,
>  		 struct liveupdate_session_retrieve_fd, token),
> +	IOCTL_OP(LIVEUPDATE_SESSION_GET_NAME, luo_session_get_name,
> +		 struct liveupdate_session_get_name, name),
>  };
>  
>  static long luo_session_ioctl(struct file *filep, unsigned int cmd,
> diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
> index c2878e3d5ef90..bdc1cedc4f944 100644
> --- a/tools/testing/selftests/liveupdate/liveupdate.c
> +++ b/tools/testing/selftests/liveupdate/liveupdate.c
> @@ -102,6 +102,22 @@ static int create_session(int lu_fd, const char *name)
>  	return args.fd;
>  }
>  
> +/* Helper function to get a session name via ioctl. */
> +static int get_session_name(int session_fd, char *name, size_t name_len)
> +{
> +	struct liveupdate_session_get_name args = {};
> +
> +	args.size = sizeof(args);
> +
> +	if (ioctl(session_fd, LIVEUPDATE_SESSION_GET_NAME, &args))
> +		return -errno;
> +
> +	strncpy(name, (char *)args.name, name_len - 1);
> +	name[name_len - 1] = '\0';
> +
> +	return 0;
> +}
> +
>  /*
>   * Test Case: Create Duplicate Session
>   *
> @@ -345,4 +361,59 @@ TEST_F(liveupdate_device, preserve_unsupported_fd)
>  	ASSERT_EQ(close(session_fd), 0);
>  }
>  
> +/*
> + * Test Case: Get Session Name
> + *
> + * Verifies that the full session name can be retrieved from a session file
> + * descriptor via ioctl.
> + */
> +TEST_F(liveupdate_device, get_session_name)
> +{
> +	char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
> +	const char *session_name = "get-name-test-session";
> +	int session_fd;
> +
> +	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> +	if (self->fd1 < 0 && errno == ENOENT)
> +		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> +	ASSERT_GE(self->fd1, 0);
> +
> +	session_fd = create_session(self->fd1, session_name);
> +	ASSERT_GE(session_fd, 0);
> +
> +	ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
> +	ASSERT_STREQ(name_buf, session_name);
> +
> +	ASSERT_EQ(close(session_fd), 0);
> +}
> +
> +/*
> + * Test Case: Get Session Name at Maximum Length
> + *
> + * Verifies that a session name using the full LIVEUPDATE_SESSION_NAME_LENGTH
> + * (minus the null terminator) can be correctly retrieved.
> + */
> +TEST_F(liveupdate_device, get_session_name_max_length)
> +{
> +	char name_buf[LIVEUPDATE_SESSION_NAME_LENGTH] = {};
> +	char long_name[LIVEUPDATE_SESSION_NAME_LENGTH];
> +	int session_fd;
> +
> +	memset(long_name, 'A', sizeof(long_name) - 1);
> +	long_name[sizeof(long_name) - 1] = '\0';
> +
> +	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> +	if (self->fd1 < 0 && errno == ENOENT)
> +		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> +	ASSERT_GE(self->fd1, 0);
> +
> +	session_fd = create_session(self->fd1, long_name);
> +	ASSERT_GE(session_fd, 0);
> +
> +	ASSERT_EQ(get_session_name(session_fd, name_buf, sizeof(name_buf)), 0);
> +	ASSERT_STREQ(name_buf, long_name);
> +
> +	ASSERT_EQ(close(session_fd), 0);
> +}
> +
>  TEST_HARNESS_MAIN
> -- 
> 2.47.3
> 

Re: [PATCH v2] liveupdate: add LIVEUPDATE_SESSION_GET_NAME ioctl

[Luca Boccassi]

On Fri, 17 Apr 2026 at 22:48, Pasha Tatashin <pasha.tatashin@soleen.com> wrote:
>
> On 04-17 01:36, luca.boccassi@gmail.com wrote:
> > From: Luca Boccassi <luca.boccassi@gmail.com>
> >
> > Userspace when requesting a session via the ioctl specifies a name and
> > gets a FD, but then there is no ioctl to go back the other way and get
> > the name given a LUO session FD. This is problematic especially when
> > there is a userspace orchestrator that wants to check what FDs it is
> > handling for clients without having to do manual string scraping of
> > procfs, or without procfs at all.
> >
> > Add a ioctl to simply get the name from an FD.
> >
> > Signed-off-by: Luca Boccassi <luca.boccassi@gmail.com>
> > ---
> > This was requested by Lennart and Christian when discussing integration
> > with systemd for LUO management.
> >
> > v2: apply one fix from bot review about cleanup on error path:
> >     https://sashiko.dev/#/patchset/20260415184536.1155220-1-luca.boccassi%40gmail.com
> >     the other comments are invalid: luo is not a kmod, and the write hooks are not set up
>
> Please split into two patches, and also CC to kernel-linux.

Done in v5. I've also merged this series and the LUO_SESSION_MAGIC
series into a single series, as they modify the same unit test source
file, to avoid merge conflicts.