Currently, a file descriptor registered for preservation via the remains
globally registered with LUO until it is explicitly unregistered. This
creates a potential for resource leaks into the next kernel if the
userspace agent crashes or exits without proper cleanup before a live
update is fully initiated.
This patch ties the lifetime of FD preservation requests to the lifetime
of the open file descriptor for /dev/liveupdate, creating an implicit
"session".
When the /dev/liveupdate file descriptor is closed (either explicitly
via close() or implicitly on process exit/crash), the .release
handler, luo_release(), is now called. This handler invokes the new
function luo_unregister_all_files(), which iterates through all FDs
that were preserved through that session and unregisters them.
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
---
kernel/liveupdate/luo_files.c | 19 +++++++++++++++++++
kernel/liveupdate/luo_internal.h | 1 +
kernel/liveupdate/luo_ioctl.c | 1 +
3 files changed, 21 insertions(+)
diff --git a/kernel/liveupdate/luo_files.c b/kernel/liveupdate/luo_files.c
index 33577c9e9a64..63f8b086b785 100644
--- a/kernel/liveupdate/luo_files.c
+++ b/kernel/liveupdate/luo_files.c
@@ -721,6 +721,25 @@ int luo_unregister_file(u64 token)
return ret;
}
+/**
+ * luo_unregister_all_files - Unpreserve all currently registered files.
+ *
+ * Iterates through all file descriptors currently registered for preservation
+ * and unregisters them, freeing all associated resources. This is typically
+ * called when LUO agent exits.
+ */
+void luo_unregister_all_files(void)
+{
+ struct luo_file *luo_file;
+ unsigned long token;
+
+ luo_state_read_enter();
+ xa_for_each(&luo_files_xa_out, token, luo_file)
+ __luo_unregister_file(token);
+ luo_state_read_exit();
+ WARN_ON_ONCE(atomic64_read(&luo_files_count) != 0);
+}
+
/**
* luo_retrieve_file - Find a registered file instance by its token.
* @token: The unique token of the file instance to retrieve.
diff --git a/kernel/liveupdate/luo_internal.h b/kernel/liveupdate/luo_internal.h
index 5692196fd425..189e032d7738 100644
--- a/kernel/liveupdate/luo_internal.h
+++ b/kernel/liveupdate/luo_internal.h
@@ -37,5 +37,6 @@ void luo_do_subsystems_cancel_calls(void);
int luo_retrieve_file(u64 token, struct file **filep);
int luo_register_file(u64 token, int fd);
int luo_unregister_file(u64 token);
+void luo_unregister_all_files(void);
#endif /* _LINUX_LUO_INTERNAL_H */
diff --git a/kernel/liveupdate/luo_ioctl.c b/kernel/liveupdate/luo_ioctl.c
index 6f61569c94e8..7ca33d1c868f 100644
--- a/kernel/liveupdate/luo_ioctl.c
+++ b/kernel/liveupdate/luo_ioctl.c
@@ -137,6 +137,7 @@ static int luo_open(struct inode *inodep, struct file *filep)
static int luo_release(struct inode *inodep, struct file *filep)
{
+ luo_unregister_all_files();
atomic_set(&luo_device_in_use, 0);
return 0;
--
2.50.1.565.gc32cd1483b-goog
