From: Jonathan Cameron Jonathan.Cameron@huawei.com
An example is the encoding of ECC signatures used by the ECDSA signature verification code. A user is the new SPDM support where raw signatures are returned by the responder. These can then be encoded so that we can pass them to signature_verify()
Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com --- include/linux/asn1_encoder.h | 3 ++ lib/asn1_encoder.c | 54 ++++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+)
diff --git a/include/linux/asn1_encoder.h b/include/linux/asn1_encoder.h index 08cd0c2ad34f..30c3ebacd46c 100644 --- a/include/linux/asn1_encoder.h +++ b/include/linux/asn1_encoder.h @@ -19,6 +19,9 @@ unsigned char * asn1_encode_tag(unsigned char *data, const unsigned char *end_data, u32 tag, const unsigned char *string, int len); unsigned char * +asn1_encode_integer_large_positive(unsigned char *data, const unsigned char *end_data, + u32 tag, const unsigned char *integer, int len); +unsigned char * asn1_encode_octet_string(unsigned char *data, const unsigned char *end_data, const unsigned char *string, u32 len); diff --git a/lib/asn1_encoder.c b/lib/asn1_encoder.c index 27bbe891714f..47ff50f478cd 100644 --- a/lib/asn1_encoder.c +++ b/lib/asn1_encoder.c @@ -317,6 +317,60 @@ asn1_encode_tag(unsigned char *data, const unsigned char *end_data, } EXPORT_SYMBOL_GPL(asn1_encode_tag);
+unsigned char * +asn1_encode_integer_large_positive(unsigned char *data, const unsigned char *end_data, + u32 tag, const unsigned char *integer, int len) +{ + int data_len = end_data - data; + unsigned char *d = &data[2]; + bool found = false; + int i; + + if (WARN(tag > 30, "ASN.1 tag can't be > 30")) + return ERR_PTR(-EINVAL); + + if (!integer && WARN(len > 127, + "BUG: recode tag is too big (>127)")) + return ERR_PTR(-EINVAL); + + if (IS_ERR(data)) + return data; + + if (data_len < 3) + return ERR_PTR(-EINVAL); + + + data[0] = _tagn(UNIV, PRIM, tag); + /* Leave space for length */ + data_len -= 2; + + for (i = 0; i < len; i++) { + int byte = integer[i]; + + if (!found && byte == 0) + continue; + + /* + * as per encode_integer + */ + if (!found && (byte & 0x80)) { + *d++ = 0; + data_len--; + } + found = true; + if (data_len == 0) + return ERR_PTR(-EINVAL); + + *d++ = byte; + data_len--; + } + + data[1] = d - data - 2; + + return d; +} +EXPORT_SYMBOL_GPL(asn1_encode_integer_large_positive); + /** * asn1_encode_octet_string() - encode an ASN.1 OCTET STRING * @data: pointer to encode at