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e155858dd9
Allows author of IPE policy to indicate trust for a singular dm-verity volume, identified by roothash, through "dmverity_roothash" and all signed and validated dm-verity volumes, through "dmverity_signature". Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> [PM: fixed some line length issues in the comments] Signed-off-by: Paul Moore <paul@paul-moore.com>
118 lines
2.7 KiB
C
118 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
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*/
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#include "digest.h"
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/**
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* ipe_digest_parse() - parse a digest in IPE's policy.
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* @valstr: Supplies the string parsed from the policy.
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*
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* Digests in IPE are defined in a standard way:
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* <alg_name>:<hex>
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*
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* Use this function to create a property to parse the digest
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* consistently. The parsed digest will be saved in @value in IPE's
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* policy.
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*
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* Return: The parsed digest_info structure on success. If an error occurs,
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* the function will return the error value (via ERR_PTR).
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*/
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struct digest_info *ipe_digest_parse(const char *valstr)
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{
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struct digest_info *info = NULL;
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char *sep, *raw_digest;
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size_t raw_digest_len;
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u8 *digest = NULL;
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char *alg = NULL;
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int rc = 0;
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info = kzalloc(sizeof(*info), GFP_KERNEL);
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if (!info)
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return ERR_PTR(-ENOMEM);
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sep = strchr(valstr, ':');
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if (!sep) {
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rc = -EBADMSG;
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goto err;
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}
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alg = kstrndup(valstr, sep - valstr, GFP_KERNEL);
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if (!alg) {
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rc = -ENOMEM;
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goto err;
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}
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raw_digest = sep + 1;
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raw_digest_len = strlen(raw_digest);
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info->digest_len = (raw_digest_len + 1) / 2;
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digest = kzalloc(info->digest_len, GFP_KERNEL);
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if (!digest) {
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rc = -ENOMEM;
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goto err;
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}
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rc = hex2bin(digest, raw_digest, info->digest_len);
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if (rc < 0) {
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rc = -EINVAL;
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goto err;
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}
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info->alg = alg;
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info->digest = digest;
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return info;
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err:
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kfree(alg);
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kfree(digest);
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kfree(info);
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return ERR_PTR(rc);
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}
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/**
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* ipe_digest_eval() - evaluate an IPE digest against another digest.
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* @expected: Supplies the policy-provided digest value.
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* @digest: Supplies the digest to compare against the policy digest value.
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*
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* Return:
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* * %true - digests match
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* * %false - digests do not match
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*/
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bool ipe_digest_eval(const struct digest_info *expected,
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const struct digest_info *digest)
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{
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return (expected->digest_len == digest->digest_len) &&
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(!strcmp(expected->alg, digest->alg)) &&
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(!memcmp(expected->digest, digest->digest, expected->digest_len));
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}
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/**
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* ipe_digest_free() - free an IPE digest.
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* @info: Supplies a pointer the policy-provided digest to free.
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*/
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void ipe_digest_free(struct digest_info *info)
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{
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if (IS_ERR_OR_NULL(info))
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return;
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kfree(info->alg);
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kfree(info->digest);
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kfree(info);
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}
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/**
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* ipe_digest_audit() - audit a digest that was sourced from IPE's policy.
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* @ab: Supplies the audit_buffer to append the formatted result.
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* @info: Supplies a pointer to source the audit record from.
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*
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* Digests in IPE are audited in this format:
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* <alg_name>:<hex>
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*/
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void ipe_digest_audit(struct audit_buffer *ab, const struct digest_info *info)
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{
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audit_log_untrustedstring(ab, info->alg);
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audit_log_format(ab, ":");
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audit_log_n_hex(ab, info->digest, info->digest_len);
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}
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