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SubjectRe: [PATCH v10 5/6] IMA: Add support to limit measuring keys
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On Wed, 2019-12-04 at 14:41 -0800, Lakshmi Ramasubramanian wrote:
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 1525a28fd705..5db990c8b02d 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -356,6 +357,51 @@ int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
> return NOTIFY_OK;
> }
>
> +/**
> + * ima_match_keyring - determine whether the keyring matches the measure rule
> + * @rule: a pointer to a rule
> + * @keyring: name of the keyring to match against the measure rule
> + * @cred: a pointer to a credentials structure for user validation
> + *
> + * Returns true if keyring matches one in the rule, false otherwise.
> + */
> +static bool ima_match_keyring(struct ima_rule_entry *rule,
> + const char *keyring, const struct cred *cred)
> +{
> + char *keyrings, *next_keyring, *keyrings_ptr;
> + bool matched = false;
> +
> + /* If "keyrings=" is not specified all keys are measured. */

With the addiitonal "uid" support this isn't necessarily true any
more.

Mimi

> + if (!rule->keyrings)
> + return true;
> +
> + if (!keyring)
> + return false;
> +
> + if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
> + return false;
> +
> + keyrings = kstrdup(rule->keyrings, GFP_KERNEL);
> + if (!keyrings)
> + return false;
> +
> + /*
> + * "keyrings=" is specified in the policy in the format below:
> + * keyrings=.builtin_trusted_keys|.ima|.evm
> + */
> + keyrings_ptr = keyrings;
> + while ((next_keyring = strsep(&keyrings_ptr, "|")) != NULL) {
> + if (!strcmp(next_keyring, keyring)) {
> + matched = true;
> + break;
> + }
> + }
> +
> + kfree(keyrings);
> +
> + return matched;
> +}
> +

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