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 nand core and skip access to the secure regions present in a system. Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> --- drivers/mtd/nand/raw/nand_base.c | 105 +++++++++++++++++++++++++++++++ include/linux/mtd/rawnand.h | 4 ++ 2 files changed, 109 insertions(+) diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index c33fa1b1847f..c85cbd491f05 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -278,11 +278,41 @@ static int nand_block_bad(struct nand_chip *chip, loff_t ofs) return 0; } +/** + * nand_check_sec_region() - Check if the region is secured + * @chip: NAND chip object + * @offset: Offset of the region to check + * + * Checks if the region is secured by comparing the offset with the list of + * secure regions obtained from DT. Returns -EIO if the region is secured + * else 0. + */ +static int nand_check_sec_region(struct nand_chip *chip, loff_t offset) +{ + int i, j; + + /* Skip touching the secure regions if present */ + for (i = 0, j = 0; i < chip->nr_sec_regions; i++, j += 2) { + if (offset >= chip->sec_regions[j] && + (offset <= chip->sec_regions[j] + chip->sec_regions[j + 1])) + return -EIO; + } + + return 0; +} + static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) { + int ret; + if (chip->options & NAND_NO_BBM_QUIRK) return 0; + /* Check if the region is secured */ + ret = nand_check_sec_region(chip, ofs); + if (ret) + return ret; + if (chip->legacy.block_bad) return chip->legacy.block_bad(chip, ofs); @@ -397,6 +427,11 @@ static int nand_do_write_oob(struct nand_chip *chip, loff_t to, return -EINVAL; } + /* Check if the region is secured */ + ret = nand_check_sec_region(chip, to); + if (ret) + return ret; + chipnr = (int)(to >> chip->chip_shift); /* @@ -565,6 +600,11 @@ static int nand_block_isreserved(struct mtd_info *mtd, loff_t ofs) if (!chip->bbt) return 0; + + /* Check if the region is secured */ + if (nand_check_sec_region(chip, ofs)) + return -EIO; + /* Return info from the table */ return nand_isreserved_bbt(chip, ofs); } @@ -2737,6 +2777,11 @@ static int nand_read_page_swecc(struct nand_chip *chip, uint8_t *buf, uint8_t *ecc_code = chip->ecc.code_buf; unsigned int max_bitflips = 0; + /* Check if the region is secured */ + ret = nand_check_sec_region(chip, ((loff_t)page << chip->page_shift)); + if (ret) + return ret; + chip->ecc.read_page_raw(chip, buf, 1, page); for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) @@ -3127,6 +3172,11 @@ 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 */ + ret = nand_check_sec_region(chip, from); + if (ret) + return ret; + chipnr = (int)(from >> chip->chip_shift); nand_select_target(chip, chipnr); @@ -3458,6 +3508,11 @@ 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 */ + ret = nand_check_sec_region(chip, from); + if (ret) + return ret; + stats = mtd->ecc_stats; len = mtd_oobavail(mtd, ops); @@ -3709,6 +3764,11 @@ static int nand_write_page_swecc(struct nand_chip *chip, const uint8_t *buf, uint8_t *ecc_calc = chip->ecc.calc_buf; const uint8_t *p = buf; + /* Check if the region is secured */ + ret = nand_check_sec_region(chip, ((loff_t)page << chip->page_shift)); + if (ret) + return ret; + /* Software ECC calculation */ for (i = 0; eccsteps; eccsteps--, i += eccbytes, p += eccsize) chip->ecc.calculate(chip, p, &ecc_calc[i]); @@ -3979,6 +4039,11 @@ static int nand_do_write_ops(struct nand_chip *chip, loff_t to, return -EINVAL; } + /* Check if the region is secured */ + ret = nand_check_sec_region(chip, to); + if (ret) + return ret; + column = to & (mtd->writesize - 1); chipnr = (int)(to >> chip->chip_shift); @@ -4180,6 +4245,11 @@ 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 */ + ret = nand_check_sec_region(chip, instr->addr); + if (ret) + return ret; + /* Grab the lock and see if the device is available */ ret = nand_get_device(chip); if (ret) @@ -4995,10 +5065,32 @@ 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); + struct property *prop; + int length, nr_elem; + + prop = of_find_property(dn, "secure-regions", &length); + if (prop) { + nr_elem = length / sizeof(u64); + chip->nr_sec_regions = nr_elem / 2; + + chip->sec_regions = kcalloc(nr_elem, sizeof(u32), GFP_KERNEL); + if (!chip->sec_regions) + return -ENOMEM; + + of_property_read_u64_array(dn, "secure-regions", chip->sec_regions, nr_elem); + } + + return 0; +} + static int rawnand_dt_init(struct nand_chip *chip) { struct nand_device *nand = mtd_to_nanddev(nand_to_mtd(chip)); struct device_node *dn = nand_get_flash_node(chip); + int ret; if (!dn) return 0; @@ -5015,6 +5107,16 @@ static int rawnand_dt_init(struct nand_chip *chip) of_get_nand_ecc_user_config(nand); of_get_nand_ecc_legacy_user_config(chip); + /* + * 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) + return ret; + /* * If neither the user nor the NAND controller have requested a specific * ECC engine type, we will default to NAND_ECC_ENGINE_TYPE_ON_HOST. @@ -6068,6 +6170,9 @@ void nand_cleanup(struct nand_chip *chip) /* Free manufacturer priv data. */ nand_manufacturer_cleanup(chip); + /* Free secure regions data */ + kfree(chip->sec_regions); + /* Free controller specific allocations after chip identification */ nand_detach(chip); diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h index 6b3240e44310..5ae77ecf41f3 100644 --- a/include/linux/mtd/rawnand.h +++ b/include/linux/mtd/rawnand.h @@ -1086,6 +1086,8 @@ struct nand_manufacturer { * NAND Controller drivers should not modify this value, but they're * allowed to read it. * @read_retries: The number of read retry modes supported + * @sec_regions: Array representing the secure regions + * @nr_sec_regions: Number of secure regions * @controller: The hardware controller structure which is shared among multiple * independent devices * @ecc: The ECC controller structure @@ -1135,6 +1137,8 @@ struct nand_chip { unsigned int suspended : 1; int cur_cs; int read_retries; + u64 *sec_regions; + u8 nr_sec_regions; /* Externals */ struct nand_controller *controller; -- 2.25.1