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-rw-r--r--include/linux/livepatch.h2
-rw-r--r--kernel/livepatch/core.c8
-rw-r--r--kernel/livepatch/state.c36
-rw-r--r--kernel/livepatch/state.h9
4 files changed, 55 insertions, 0 deletions
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 726947338fd5..e894e74905f3 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -133,10 +133,12 @@ struct klp_object {
/**
* struct klp_state - state of the system modified by the livepatch
* @id: system state identifier (non-zero)
+ * @version: version of the change
* @data: custom data
*/
struct klp_state {
unsigned long id;
+ unsigned int version;
void *data;
};
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 1e1d87ead55c..c3512e7e0801 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -22,6 +22,7 @@
#include <asm/cacheflush.h>
#include "core.h"
#include "patch.h"
+#include "state.h"
#include "transition.h"
/*
@@ -1009,6 +1010,13 @@ int klp_enable_patch(struct klp_patch *patch)
mutex_lock(&klp_mutex);
+ if (!klp_is_patch_compatible(patch)) {
+ pr_err("Livepatch patch (%s) is not compatible with the already installed livepatches.\n",
+ patch->mod->name);
+ mutex_unlock(&klp_mutex);
+ return -EINVAL;
+ }
+
ret = klp_init_patch_early(patch);
if (ret) {
mutex_unlock(&klp_mutex);
diff --git a/kernel/livepatch/state.c b/kernel/livepatch/state.c
index 6ab15b642c0a..7ee19476de9d 100644
--- a/kernel/livepatch/state.c
+++ b/kernel/livepatch/state.c
@@ -9,6 +9,7 @@
#include <linux/livepatch.h>
#include "core.h"
+#include "state.h"
#include "transition.h"
#define klp_for_each_state(patch, state) \
@@ -81,3 +82,38 @@ out:
return last_state;
}
EXPORT_SYMBOL_GPL(klp_get_prev_state);
+
+/* Check if the patch is able to deal with the existing system state. */
+static bool klp_is_state_compatible(struct klp_patch *patch,
+ struct klp_state *old_state)
+{
+ struct klp_state *state;
+
+ state = klp_get_state(patch, old_state->id);
+
+ /* A cumulative livepatch must handle all already modified states. */
+ if (!state)
+ return !patch->replace;
+
+ return state->version >= old_state->version;
+}
+
+/*
+ * Check that the new livepatch will not break the existing system states.
+ * Cumulative patches must handle all already modified states.
+ * Non-cumulative patches can touch already modified states.
+ */
+bool klp_is_patch_compatible(struct klp_patch *patch)
+{
+ struct klp_patch *old_patch;
+ struct klp_state *old_state;
+
+ klp_for_each_patch(old_patch) {
+ klp_for_each_state(old_patch, old_state) {
+ if (!klp_is_state_compatible(patch, old_state))
+ return false;
+ }
+ }
+
+ return true;
+}
diff --git a/kernel/livepatch/state.h b/kernel/livepatch/state.h
new file mode 100644
index 000000000000..49d9c16e8762
--- /dev/null
+++ b/kernel/livepatch/state.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LIVEPATCH_STATE_H
+#define _LIVEPATCH_STATE_H
+
+#include <linux/livepatch.h>
+
+bool klp_is_patch_compatible(struct klp_patch *patch);
+
+#endif /* _LIVEPATCH_STATE_H */