[PATCH v3 2/2] ufs: rpmb: use a fixed-length RPMB dev_id
Jorge Ramirez-Ortiz via OP-TEE <[email protected]>
| Newsgroups | org.trustedfirmware.lists.op-tee,org.kernel.vger.linux-kernel,org.kernel.vger.linux-scsi |
|---|---|
| Message-ID | <[email protected]> |
The RPMB authentication key is derived from the dev_id handed to the RPMB subsystem. OP-TEE implements the eMMC RPMB flow, where the dev_id is the eMMC CID, a fixed 16-byte value, and it derives the key on that assumption. The UFS RPMB id built here is "<device_id>-R<region>", which is variable length and longer than 16 bytes. Passing it verbatim would tie the derived key to a length OP-TEE does not expect and diverge from the fixed-CID eMMC ABI, requiring OP-TEE to be taught about variable-length UFS ids. Hash the UFS id into a fixed 16-byte dev_id with blake2b instead. This keeps the derived key stable and unique per region while matching the eMMC CID layout OP-TEE relies on, so the key-derivation ABI stays identical and no OP-TEE change is needed. blake2b is used because it is already available in bootloaders such as U-Boot that must derive the same dev_id, avoiding the need to add a blake2s implementation there. Signed-off-by: Jorge Ramirez-Ortiz <[email protected]> --- drivers/ufs/Kconfig | 1 + drivers/ufs/core/ufs-rpmb.c | 9 +++++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/ufs/Kconfig b/drivers/ufs/Kconfig index f662e7ce71f1..b62c00e7ff06 100644 --- a/drivers/ufs/Kconfig +++ b/drivers/ufs/Kconfig @@ -7,6 +7,7 @@ menuconfig SCSI_UFSHCD tristate "Universal Flash Storage Controller" depends on SCSI && SCSI_DMA depends on RPMB || !RPMB + select CRYPTO_LIB_BLAKE2B if RPMB select PM_DEVFREQ select DEVFREQ_GOV_SIMPLE_ONDEMAND select NLS diff --git a/drivers/ufs/core/ufs-rpmb.c b/drivers/ufs/core/ufs-rpmb.c index d0c7ea7a36f4..a1e169ad3096 100644 --- a/drivers/ufs/core/ufs-rpmb.c +++ b/drivers/ufs/core/ufs-rpmb.c @@ -10,6 +10,7 @@ * Can Guo <[email protected]> */ +#include <crypto/blake2b.h> #include <linux/module.h> #include <linux/device.h> #include <linux/kernel.h> @@ -21,6 +22,7 @@ #include <linux/unaligned.h> #include "ufshcd-priv.h" +#define UFS_RPMB_ID_LEN 16 /* Match eMMC CID Length */ #define UFS_RPMB_SEC_PROTOCOL 0xEC /* JEDEC UFS application */ #define UFS_RPMB_SEC_PROTOCOL_ID 0x01 /* JEDEC UFS RPMB protocol ID, CDB byte3 */ @@ -153,6 +155,7 @@ static void ufs_rpmb_device_release(struct device *dev) int ufs_rpmb_probe(struct ufs_hba *hba) { struct ufs_rpmb_dev *ufs_rpmb, *it, *tmp; + u8 dev_id[UFS_RPMB_ID_LEN]; struct rpmb_dev *rdev; char *cid = NULL; int region; @@ -213,8 +216,10 @@ int ufs_rpmb_probe(struct ufs_hba *hba) goto err_out; } - descr.dev_id = cid; - descr.dev_id_len = strlen(cid); + blake2b(NULL, 0, cid, strlen(cid), dev_id, UFS_RPMB_ID_LEN); + + descr.dev_id = dev_id; + descr.dev_id_len = UFS_RPMB_ID_LEN; descr.capacity = cap; /* Register RPMB device */ -- 2.54.0