After an update to a newer barebox version with an enabled state
framework, existing data in storage memories could be overwritten.
Add a new property to check in front of every write task, if the meta
magic field only contains the magic number, zeros or ones.
Signed-off-by: Daniel Schultz <d.schultz@xxxxxxxxx>
---
.../devicetree/bindings/barebox/barebox,state.rst | 3 +++
common/state/backend_bucket_direct.c | 2 ++
common/state/backend_storage.c | 1 +
common/state/state.c | 19 ++++++++++++++++++-
common/state/state.h | 2 ++
5 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/barebox/barebox,state.rst b/Documentation/devicetree/bindings/barebox/barebox,state.rst
index cebb5f8..db5b041 100644
--- a/Documentation/devicetree/bindings/barebox/barebox,state.rst
+++ b/Documentation/devicetree/bindings/barebox/barebox,state.rst
@@ -55,6 +55,9 @@ Optional Properties
* ``algo``: A HMAC algorithm used to detect manipulation of the data
or header, sensible values follow this pattern ``hmac(<HASH>)``,
e.g. ``hmac(sha256)``. Only available for the ``backend-type`` ``raw``.
+* ``keep-previous-content``: Check if a the bucket meta magic field contains
+ other data than the magic value. If so, the backend will not write the state
+ to prevent unconditionally overwrites of existing data.
.. note:: For the ``backend-storage-type`` the keyword ``noncircular`` is still
supported as a fall back to an old storage format. Recommendation is to not
diff --git a/common/state/backend_bucket_direct.c b/common/state/backend_bucket_direct.c
index 958696e..9d6a337 100644
--- a/common/state/backend_bucket_direct.c
+++ b/common/state/backend_bucket_direct.c
@@ -69,6 +69,8 @@ static int state_backend_bucket_direct_read(struct state_backend_storage_bucket
if (meta.magic == direct_magic) {
read_len = meta.written_length;
} else {
+ if (meta.magic != ~0 && !!meta.magic)
+ bucket->wrong_magic = 1;
if (!IS_ENABLED(CONFIG_STATE_BACKWARD_COMPATIBLE)) {
dev_err(direct->dev, "No meta data header found\n");
dev_dbg(direct->dev, "Enable backward compatibility or increase stride size\n");
diff --git a/common/state/backend_storage.c b/common/state/backend_storage.c
index c6ebe86..f0a169d 100644
--- a/common/state/backend_storage.c
+++ b/common/state/backend_storage.c
@@ -152,6 +152,7 @@ int state_storage_read(struct state_backend_storage *storage,
* one we want to use.
*/
list_for_each_entry(bucket, &storage->buckets, bucket_list) {
+ bucket->wrong_magic = 0;
ret = bucket->read(bucket, &bucket->buf, &bucket->len);
if (ret == -EUCLEAN)
bucket->needs_refresh = 1;
diff --git a/common/state/state.c b/common/state/state.c
index 6399bd3..e110542 100644
--- a/common/state/state.c
+++ b/common/state/state.c
@@ -44,6 +44,9 @@ int state_save(struct state *state)
void *buf;
ssize_t len;
int ret;
+ struct state_backend_storage_bucket *bucket;
+ struct state_backend_storage *storage;
+ bool has_content;
if (!state->dirty)
return 0;
@@ -55,7 +58,18 @@ int state_save(struct state *state)
return ret;
}
- ret = state_storage_write(&state->storage, buf, len);
+ storage = &state->storage;
+ if (state->keep_prev_content) {
+ has_content = 0;
+ list_for_each_entry(bucket, &storage->buckets, bucket_list)
+ has_content |= bucket->wrong_magic;
+ if (has_content) {
+ dev_dbg(&state->dev, "Found content on a backend.\n");
+ goto out;
+ }
+ }
+
+ ret = state_storage_write(storage, buf, len);
if (ret) {
dev_err(&state->dev, "Failed to write packed state, %d\n", ret);
goto out;
@@ -605,6 +619,9 @@ struct state *state_new_from_node(struct device_node *node, char *path,
}
}
+ state->keep_prev_content = of_property_read_bool(node,
+ "keep-previous-content");
+
state->backend_path = xstrdup(path);
ret = of_property_read_string(node, "backend-type", &backend_type);
diff --git a/common/state/state.h b/common/state/state.h
index fcc6b9f..a411b96 100644
--- a/common/state/state.h
+++ b/common/state/state.h
@@ -46,6 +46,7 @@ struct state_backend_storage_bucket {
void *buf;
ssize_t len;
bool needs_refresh;
+ bool wrong_magic;
};
/**
@@ -105,6 +106,7 @@ struct state {
char *of_path;
const char *name;
uint32_t magic;
+ bool keep_prev_content;
struct list_head variables; /* Sorted list of variables */
unsigned int dirty;
--
2.7.4
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