From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.phytec.eu ([217.6.246.34] helo=root.phytec.de) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1f6YIA-0004rh-Mm for barebox@lists.infradead.org; Thu, 12 Apr 2018 09:13:20 +0000 Received: from idefix.phytec.de (idefix.phytec.de [172.16.0.10]) by root.phytec.de (Postfix) with ESMTP id A98FBA0023F for ; Thu, 12 Apr 2018 11:13:20 +0200 (CEST) From: Daniel Schultz Date: Thu, 12 Apr 2018 11:13:01 +0200 Message-Id: <1523524382-19217-1-git-send-email-d.schultz@phytec.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: [PATCH v2 1/2] common: state: Add property to protect existing data To: barebox@lists.infradead.org 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 --- 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()``, 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 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox