Messages in this thread | | | From | Xiongwei Song <> | Date | Mon, 3 Sep 2018 16:31:56 +0800 | Subject | Question about pe file verification |
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Hi,
Some code logic I don't understand about the function pefile_digest_pe_contents in the file crypto/asymmetric_keys/verify_pefile.c. At the end of pefile_digest_pe_contents, please see the comment [sxw] below:
static int pefile_digest_pe_contents(const void *pebuf, unsigned int pelen, struct pefile_context *ctx, struct shash_desc *desc) { unsigned *canon, tmp, loop, i, hashed_bytes; int ret;
...... [sxw] I assume the image has signed by sbsign tool, there is a certificate at the end of image file. if (pelen > hashed_bytes) { tmp = hashed_bytes + ctx->certs_size; [sxw] The tmp value is the end of certificate.
ret = crypto_shash_update(desc, pebuf + hashed_bytes, [sxw] The data address is the beginning of the certificate. Why do we need to hash the certification data block?
pelen - tmp); [sxw] However, the data length doesn't include the certificate, sometimes it's zero.
if (ret < 0) return ret; }
return 0; }
Is that for a special consider or something else?
Regards, Xiongwei
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