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authorManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>2021-04-02 20:31:27 +0530
committerMiquel Raynal <miquel.raynal@bootlin.com>2021-04-07 10:06:24 +0200
commit13b89768275d6ca9764bf91449e4cafe46ba706b (patch)
treea2acd9ff585acbd4c6b10064f140284e23bcf03a /drivers/mtd/nand
parentee590106c331ad54df9da3052b5c52014b2edb0b (diff)
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 <manivannan.sadhasivam@linaro.org> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://lore.kernel.org/linux-mtd/20210402150128.29128-4-manivannan.sadhasivam@linaro.org
Diffstat (limited to 'drivers/mtd/nand')
-rw-r--r--drivers/mtd/nand/raw/nand_base.c100
1 files changed, 99 insertions, 1 deletions
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);