From 13b89768275d6ca9764bf91449e4cafe46ba706b Mon Sep 17 00:00:00 2001 From: Manivannan Sadhasivam Date: Fri, 2 Apr 2021 20:31:27 +0530 Subject: mtd: rawnand: Add support for secure regions in NAND memory On a typical end product, a vendor may choose to secure some regions in the NAND memory which are supposed to stay intact between FW upgrades. The access to those regions will be blocked by a secure element like Trustzone. So the normal world software like Linux kernel should not touch these regions (including reading). The regions are declared using a NAND chip DT property, "secure-regions". So let's make use of this property in the raw NAND core and skip access to the secure regions present in a system. Signed-off-by: Manivannan Sadhasivam Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/linux-mtd/20210402150128.29128-4-manivannan.sadhasivam@linaro.org --- drivers/mtd/nand/raw/nand_base.c | 100 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 99 insertions(+), 1 deletion(-) (limited to 'drivers/mtd') diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index a984cda86e2d..fb072c444495 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -278,11 +278,48 @@ static int nand_block_bad(struct nand_chip *chip, loff_t ofs) return 0; } +/** + * nand_region_is_secured() - Check if the region is secured + * @chip: NAND chip object + * @offset: Offset of the region to check + * @size: Size of the region to check + * + * Checks if the region is secured by comparing the offset and size with the + * list of secure regions obtained from DT. Returns true if the region is + * secured else false. + */ +static bool nand_region_is_secured(struct nand_chip *chip, loff_t offset, u64 size) +{ + int i; + + /* Skip touching the secure regions if present */ + for (i = 0; i < chip->nr_secure_regions; i++) { + const struct nand_secure_region *region = &chip->secure_regions[i]; + + if (offset + size <= region->offset || + offset >= region->offset + region->size) + continue; + + pr_debug("%s: Region 0x%llx - 0x%llx is secured!", + __func__, offset, offset + size); + + return true; + } + + return false; +} + static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) { + struct mtd_info *mtd = nand_to_mtd(chip); + if (chip->options & NAND_NO_BBM_QUIRK) return 0; + /* Check if the region is secured */ + if (nand_region_is_secured(chip, ofs, mtd->erasesize)) + return -EIO; + if (chip->legacy.block_bad) return chip->legacy.block_bad(chip, ofs); @@ -397,6 +434,10 @@ static int nand_do_write_oob(struct nand_chip *chip, loff_t to, return -EINVAL; } + /* Check if the region is secured */ + if (nand_region_is_secured(chip, to, ops->ooblen)) + return -EIO; + chipnr = (int)(to >> chip->chip_shift); /* @@ -3128,6 +3169,10 @@ static int nand_do_read_ops(struct nand_chip *chip, loff_t from, int retry_mode = 0; bool ecc_fail = false; + /* Check if the region is secured */ + if (nand_region_is_secured(chip, from, readlen)) + return -EIO; + chipnr = (int)(from >> chip->chip_shift); nand_select_target(chip, chipnr); @@ -3459,6 +3504,10 @@ static int nand_do_read_oob(struct nand_chip *chip, loff_t from, pr_debug("%s: from = 0x%08Lx, len = %i\n", __func__, (unsigned long long)from, readlen); + /* Check if the region is secured */ + if (nand_region_is_secured(chip, from, readlen)) + return -EIO; + stats = mtd->ecc_stats; len = mtd_oobavail(mtd, ops); @@ -3980,6 +4029,10 @@ static int nand_do_write_ops(struct nand_chip *chip, loff_t to, return -EINVAL; } + /* Check if the region is secured */ + if (nand_region_is_secured(chip, to, writelen)) + return -EIO; + column = to & (mtd->writesize - 1); chipnr = (int)(to >> chip->chip_shift); @@ -4181,6 +4234,10 @@ int nand_erase_nand(struct nand_chip *chip, struct erase_info *instr, if (check_offs_len(chip, instr->addr, instr->len)) return -EINVAL; + /* Check if the region is secured */ + if (nand_region_is_secured(chip, instr->addr, instr->len)) + return -EIO; + /* Grab the lock and see if the device is available */ ret = nand_get_device(chip); if (ret) @@ -4996,6 +5053,31 @@ static bool of_get_nand_on_flash_bbt(struct device_node *np) return of_property_read_bool(np, "nand-on-flash-bbt"); } +static int of_get_nand_secure_regions(struct nand_chip *chip) +{ + struct device_node *dn = nand_get_flash_node(chip); + int nr_elem, i, j; + + nr_elem = of_property_count_elems_of_size(dn, "secure-regions", sizeof(u64)); + if (!nr_elem) + return 0; + + chip->nr_secure_regions = nr_elem / 2; + chip->secure_regions = kcalloc(chip->nr_secure_regions, sizeof(*chip->secure_regions), + GFP_KERNEL); + if (!chip->secure_regions) + return -ENOMEM; + + for (i = 0, j = 0; i < chip->nr_secure_regions; i++, j += 2) { + of_property_read_u64_index(dn, "secure-regions", j, + &chip->secure_regions[i].offset); + of_property_read_u64_index(dn, "secure-regions", j + 1, + &chip->secure_regions[i].size); + } + + return 0; +} + static int rawnand_dt_init(struct nand_chip *chip) { struct nand_device *nand = mtd_to_nanddev(nand_to_mtd(chip)); @@ -5952,6 +6034,16 @@ static int nand_scan_tail(struct nand_chip *chip) goto err_free_interface_config; } + /* + * Look for secure regions in the NAND chip. These regions are supposed + * to be protected by a secure element like Trustzone. So the read/write + * accesses to these regions will be blocked in the runtime by this + * driver. + */ + ret = of_get_nand_secure_regions(chip); + if (ret) + goto err_free_interface_config; + /* Check, if we should skip the bad block table scan */ if (chip->options & NAND_SKIP_BBTSCAN) return 0; @@ -5959,10 +6051,13 @@ static int nand_scan_tail(struct nand_chip *chip) /* Build bad block table */ ret = nand_create_bbt(chip); if (ret) - goto err_free_interface_config; + goto err_free_secure_regions; return 0; +err_free_secure_regions: + kfree(chip->secure_regions); + err_free_interface_config: kfree(chip->best_interface_config); @@ -6050,6 +6145,9 @@ void nand_cleanup(struct nand_chip *chip) nanddev_cleanup(&chip->base); + /* Free secure regions data */ + kfree(chip->secure_regions); + /* Free bad block table memory */ kfree(chip->bbt); kfree(chip->data_buf); -- cgit v1.2.3