Parsing ASCII values is hard as hex values can be declared in many ways
and OEM never follow a genera rules. This is especially problematic for
parsing MAC address writte in ASCII format where an hex values can be
written in 2 different format:
- a Full format with leading 0, 01 02 06 0A
- a Reduced format with trimmed leading 0, 1 2 6 A
The current U-Boot-env driver assume that the Full format is always used
by parsting the NVMEM cell size and expect always the form of
XX:XX:XX:XX:XX:XX to pass it directly to mac_pton that expects this
format.
Reality is that it's common for OEM to use the reduced format resulting
in MAC address in the format of XX:a:XX:XX:XX:XX:XX or a:XX:XX:XX:XX:XX
or XX:XX:XX:XX:XX:a.
To handle these special format additional care is needed.
Some additional logic are added to "normalize" the MAC address in ASCII
to a format that is accepted by mac_pton.
As using the NVMEM cell size is not enough anymore, some additional
validation are done by checking if we have at least a format of
X:X:X:X:X:X by checking if we have at least 5 ':' char while checking
the NVMEM cell. The size validation is changed to check a range of
ETH_ALEN + 5 (assuming a min valid MAC address of X:X:X:X:X:X) and
the full form by checking 3 * ETH_ALEN -1 (for the full format
XX:XX:XX:XX:XX:XX)
The parsing function try to be as redable as possible while saving some
code duplication and skip the use of memcpy function as the post_process
is called very little time just on driver probe.
Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
---
drivers/nvmem/u-boot-env.c | 50 ++++++++++++++++++++++++++++++++++++--
1 file changed, 48 insertions(+), 2 deletions(-)
diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
index b64c37308789..e33565e872f8 100644
--- a/drivers/nvmem/u-boot-env.c
+++ b/drivers/nvmem/u-boot-env.c
@@ -76,12 +76,58 @@ static int u_boot_env_read(void *context, unsigned int offset, void *val,
static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
unsigned int offset, void *buf, size_t bytes)
{
+ u8 *src_mac = buf;
u8 mac[ETH_ALEN];
- if (bytes != 3 * ETH_ALEN - 1)
+ if (bytes < ETH_ALEN + 5 || bytes > 3 * ETH_ALEN - 1)
return -EINVAL;
- if (!mac_pton(buf, mac))
+ /* ASCII address might need to be normalized, try to parse it */
+ if (bytes != 3 * ETH_ALEN - 1) {
+ u8 tmp_mac[3 * ETH_ALEN - 1];
+ int i = 0, j = 0;
+
+ while (i < bytes) {
+ /* First check if we need to handle a reduced section
+ * or we are handling the last byte.
+ * Example of reduced section:
+ * - a:XX:XX:XX:XX:XX
+ * - XX:a:XX:XX:XX:XX
+ * - XX:XX:XX:XX:XX:a
+ */
+ if (src_mac[i + 1] == ':' || i + 1 == bytes) {
+ tmp_mac[j] = '0';
+ tmp_mac[j + 1] = src_mac[i];
+ if (src_mac[i + 1] == ':')
+ tmp_mac[j + 2] = src_mac[i + 1];
+ i += 2;
+ /* Handle a full section or we are handling the last 2 byte.
+ * Example of full section:
+ * - aa:XX:XX:XX:XX:XX
+ * - XX:aa:XX:XX:XX:XX
+ * - XX:XX:XX:XX:XX:aa
+ */
+ } else if (src_mac[i + 2] == ':' || i + 2 == bytes) {
+ tmp_mac[j] = src_mac[i];
+ tmp_mac[j + 1] = src_mac[i + 1];
+ if (src_mac[i + 2] == ':')
+ tmp_mac[j + 2] = src_mac[i + 2];
+ i += 3;
+ /* Return -EINVAL if we have a not valid ascii address.
+ * We can use the logic of missing ':' to validate a
+ * correct ASCII address.
+ */
+ } else {
+ return -EINVAL;
+ }
+ j += 3;
+ }
+
+ /* Parse the normalized mac instead of the nvmem cell */
+ src_mac = tmp_mac;
+ }
+
+ if (!mac_pton(src_mac, mac))
return -EINVAL;
if (index)
--
2.40.1
