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
---
drivers/mtd/nand/raw/nand_base.c | 107 ++-
include/linux/mtd/rawnand.h | 14
2 files changed, 120 insertions(+), 1 deletion(-)
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index c33fa1b1847f..c216d3eca915 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -278,11 +278,50 @@ 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 =
>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);
+ int last_page = ((mtd->erasesize - mtd->writesize) >>
+chip->page_shift) & chip->pagemask;
+
if (chip->options & NAND_NO_BBM_QUIRK)
return 0;
+ /* Check if the region is secured */
+ if (nand_region_is_secured(chip, ofs, last_page))
+ return -EIO;
+
if (chip->legacy.block_bad)
return chip->legacy.block_bad(chip, ofs);
@@ -397,6 +436,10 @@ 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);
/*
@@ -565,6 +608,11 @@ 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_region_is_secured(chip, ofs, 0))
+ return -EIO;
+
/* Return info from the table */
return nand_isreserved_bbt(chip, ofs);
}
@@ -3127,6 +3175,10 @@ 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);
@@ -3458,6 +3510,10 @@ 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);
@@ -3979,6 +4035,10 @@ 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);
@@ -4180,6 +4240,10 @@ 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)
@@ -4995,6 +5059,31 @@ static bool of_get_nand_on_flash_bbt(struct device_node
*np)
return
