Add a helper encoding a positive integer from a byte array in big-endian format.
Signed-off-by: Jarkko Sakkinen <[email protected]> --- include/linux/asn1_encoder.h | 3 ++ lib/asn1_encoder.c | 62 ++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) diff --git a/include/linux/asn1_encoder.h b/include/linux/asn1_encoder.h index d17484dffb74..e206bd425854 100644 --- a/include/linux/asn1_encoder.h +++ b/include/linux/asn1_encoder.h @@ -12,6 +12,9 @@ unsigned char * asn1_encode_integer(unsigned char *data, const unsigned char *end_data, s64 integer); unsigned char * +asn1_encode_integer_bytes(unsigned char *data, const unsigned char *end_data, + const unsigned char *integer, u32 integer_len); +unsigned char * asn1_encode_oid(unsigned char *data, const unsigned char *end_data, u32 oid[], int oid_len); unsigned char * diff --git a/lib/asn1_encoder.c b/lib/asn1_encoder.c index 92f35aae13b1..22e0acd6fe08 100644 --- a/lib/asn1_encoder.c +++ b/lib/asn1_encoder.c @@ -10,6 +10,8 @@ #include <linux/string.h> #include <linux/module.h> +static int asn1_encode_length(unsigned char **data, int *data_len, int len); + /** * asn1_encode_integer() - encode positive integer to ASN.1 * @data: pointer to the pointer to the data @@ -85,6 +87,66 @@ asn1_encode_integer(unsigned char *data, const unsigned char *end_data, } EXPORT_SYMBOL_GPL(asn1_encode_integer); +/** + * asn1_encode_integer_bytes() - encode positive integer bytes to ASN.1 + * @data: pointer to the pointer to the data + * @end_data: end of data pointer, points one beyond last usable byte in @data + * @bytes: integer bytes + * @bytes_len: amount of bytes + * + * Encode a positive integer from a byte array in big-endian format. Strip + * leading zeros. + */ +unsigned char * +asn1_encode_integer_bytes(unsigned char *data, const unsigned char *end_data, + const unsigned char *bytes, u32 bytes_len) +{ + static const unsigned char zero; + int data_len = end_data - data; + bool add_pad = false; + int ret; + + if (IS_ERR(data)) + return data; + + if (!bytes || !bytes_len) + return ERR_PTR(-EINVAL); + + /* Strip leading zeros: */ + while (bytes_len > 1 && bytes[0] == 0) { + bytes++; + bytes_len--; + } + + if (!bytes_len) { + bytes = &zero; + bytes_len = 1; + } else { + add_pad = bytes[0] & 0x80; + } + + if (data_len < 2) + return ERR_PTR(-EINVAL); + + *(data++) = _tag(UNIV, PRIM, INT); + data_len--; + + ret = asn1_encode_length(&data, &data_len, bytes_len + add_pad); + if (ret) + return ERR_PTR(ret); + + if (data_len < bytes_len + add_pad) + return ERR_PTR(-EINVAL); + + if (add_pad) + *(data++) = 0; + + memcpy(data, bytes, bytes_len); + data += bytes_len; + return data; +} +EXPORT_SYMBOL_GPL(asn1_encode_integer_bytes); + /* calculate the base 128 digit values setting the top bit of the first octet */ static int asn1_encode_oid_digit(unsigned char **_data, int *data_len, u32 oid) { -- 2.47.3
