boot: fit: support generating DM verity cmdline parameters

Add fit_verity_build_cmdline(): when a FILESYSTEM loadable carries a
dm-verity subnode, construct the dm-mod.create= kernel cmdline parameter
from the verity metadata (block-size, data-blocks, algo, root-hash,
salt) and append it to bootargs.

Also add dm-mod.waitfor=/dev/fit0[,/dev/fitN] for each dm-verity device
so the kernel waits for the underlying FIT block device to appear before
setting up device-mapper targets. This is needed when the block driver
probes late, e.g. because it depends on NVMEM calibration data.

The dm-verity target references /dev/fitN where N is the loadable's
index in the configuration -- matching the order Linux's FIT block
driver assigns block devices.  hash-start-block is read directly from
the FIT dm-verity node; mkimage ensures its value equals num-data-blocks
by invoking veritysetup with --no-superblock.

Signed-off-by: Daniel Golle <[email protected]>
Reviewed-by: Simon Glass <[email protected]>

1 files changed, 79 insertions, 1 deletions

diff --git a/include/image.h b/include/image.h
index 482446a8115..fe2361a667e 100644
--- a/include/image.h
+++ b/include/image.h
@@ -396,7 +396,19 @@ struct bootm_headers {
 	ulong		cmdline_start;
 	ulong		cmdline_end;
 	struct bd_info		*kbd;
-#endif
+
+#if CONFIG_IS_ENABLED(FIT_VERITY)
+	/*
+	 * dm-verity kernel command-line fragments, populated during FIT
+	 * parsing by fit_verity_build_cmdline().  Bootmeths can check
+	 * fit_verity_active() between bootm states, and
+	 * fit_verity_apply_bootargs() appends these to the "bootargs"
+	 * env var during BOOTM_STATE_OS_PREP.
+	 */
+	char *dm_mod_create;
+	char *dm_mod_waitfor;
+#endif /* FIT_VERITY */
+#endif /* !USE_HOSTCC */
 
 	int		verify;		/* env_get("verify")[0] != 'n' */
 
@@ -756,6 +768,72 @@ int fit_image_load(struct bootm_headers *images, ulong addr,
 		   int arch, int image_ph_type, int bootstage_id,
 		   enum fit_load_op load_op, ulong *datap, ulong *lenp);
 
+#if !defined(USE_HOSTCC) && CONFIG_IS_ENABLED(FIT_VERITY)
+/**
+ * fit_verity_build_cmdline() - build dm-verity cmdline from FIT metadata
+ * @fit:		pointer to the FIT blob
+ * @conf_noffset:	configuration node offset in @fit
+ * @images:		bootm headers; dm_mod_create / dm_mod_waitfor are
+ *			populated on success
+ *
+ * Called automatically from boot_get_loadable() during FIT parsing.
+ * For each IH_TYPE_FILESYSTEM loadable with a dm-verity subnode,
+ * builds the corresponding dm target specification.
+ *
+ * Return: 0 on success, -ve errno on error
+ */
+int fit_verity_build_cmdline(const void *fit, int conf_noffset,
+			     struct bootm_headers *images);
+
+/**
+ * fit_verity_apply_bootargs() - append dm-verity params to bootargs env
+ * @images:	bootm headers with dm-verity cmdline fragments
+ *
+ * Called from BOOTM_STATE_OS_PREP before bootm_process_cmdline_env().
+ *
+ * Return: 0 on success, -ve errno on error
+ */
+int fit_verity_apply_bootargs(const struct bootm_headers *images);
+
+/**
+ * fit_verity_active() - check whether dm-verity targets were found
+ * @images:	bootm headers
+ *
+ * Return: true if at least one dm-verity target was built
+ */
+static inline bool fit_verity_active(const struct bootm_headers *images)
+{
+	return !!images->dm_mod_create;
+}
+
+/**
+ * fit_verity_free() - free dm-verity cmdline allocations
+ * @images:	bootm headers
+ */
+void fit_verity_free(struct bootm_headers *images);
+
+#else /* !FIT_VERITY */
+
+static inline int fit_verity_build_cmdline(const void *fit, int conf_noffset,
+					   struct bootm_headers *images)
+{
+	return 0;
+}
+
+static inline int fit_verity_apply_bootargs(const struct bootm_headers *images)
+{
+	return 0;
+}
+
+static inline bool fit_verity_active(const struct bootm_headers *images)
+{
+	return false;
+}
+
+static inline void fit_verity_free(struct bootm_headers *images) {}
+
+#endif /* FIT_VERITY */
+
 /**
  * image_locate_script() - Locate the raw script in an image
  *