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>
---
Changes:
v2: Added check for circular backend
Improved error message if content was found
.../devicetree/bindings/barebox/barebox,state.rst | 3 +++
common/state/backend_bucket_circular.c | 8 +++++---
common/state/backend_bucket_direct.c | 2 ++
common/state/state.c | 19 ++++++++++++++++++-
common/state/state.h | 2 ++
5 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/barebox/barebox,state.rst b/Documentation/devicetree/bindings/barebox/barebox,state.rst
index 872bac0..2893937 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_circular.c b/common/state/backend_bucket_circular.c
index 2324903..933493e 100644
--- a/common/state/backend_bucket_circular.c
+++ b/common/state/backend_bucket_circular.c
@@ -396,11 +396,13 @@ static int state_backend_bucket_circular_init(
meta = (struct state_backend_storage_bucket_circular_meta *)
(buf + sub_offset + circ->writesize - sizeof(*meta));
- if (meta->magic != circular_magic)
+ if (meta->magic != circular_magic) {
written_length = 0;
- else
+ if (meta->magic != ~0 && !!meta->magic)
+ bucket->wrong_magic = 1;
+ } else {
written_length = meta->written_length;
-
+ }
break;
}
}
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/state.c b/common/state/state.c
index 73dfb58..25d9502 100644
--- a/common/state/state.c
+++ b/common/state/state.c
@@ -44,6 +44,8 @@ int state_save(struct state *state)
void *buf;
ssize_t len;
int ret;
+ struct state_backend_storage_bucket *bucket;
+ struct state_backend_storage *storage;
if (!state->dirty)
return 0;
@@ -55,7 +57,19 @@ int state_save(struct state *state)
return ret;
}
- ret = state_storage_write(&state->storage, buf, len);
+ storage = &state->storage;
+ if (state->keep_prev_content) {
+ bool has_content = 0;
+ list_for_each_entry(bucket, &storage->buckets, bucket_list)
+ has_content |= bucket->wrong_magic;
+ if (has_content) {
+ dev_err(&state->dev, "Found foreign content on backend, won't overwrite.\n");
+ ret = -EPERM;
+ 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;
@@ -623,6 +637,9 @@ struct state *state_new_from_node(struct device_node *node, bool readonly)
of_property_read_string(node, "backend-storage-type", &storage_type);
+ state->keep_prev_content = of_property_read_bool(node,
+ "keep-previous-content");
+
ret = state_format_init(state, backend_type, node, alias);
if (ret)
goto out_release_state;
diff --git a/common/state/state.h b/common/state/state.h
index 6670523..3a0662f 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 */
--
2.7.4
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