On 2020-12-11 15:58:03, Tushar Sugandhi wrote:
> A new IMA policy rule is needed for the IMA hook
> ima_measure_critical_data() and the corresponding func CRITICAL_DATA for
> measuring the input buffer. The policy rule should ensure the buffer
> would get measured only when the policy rule allows the action. The
> policy rule should also support the necessary constraints (flags etc.)
> for integrity critical buffer data measurements.
>
> Add a policy rule to define the constraints for restricting integrity
> critical data measurements.
>
> Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
> ---
> Documentation/ABI/testing/ima_policy | 2 +-
> security/integrity/ima/ima_policy.c | 34 ++++++++++++++++++++++++----
> 2 files changed, 31 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
> index e35263f97fc1..6ec7daa87cba 100644
> --- a/Documentation/ABI/testing/ima_policy
> +++ b/Documentation/ABI/testing/ima_policy
> @@ -32,7 +32,7 @@ Description:
> func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK]MODULE_CHECK]
> [FIRMWARE_CHECK]
> [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
> - [KEXEC_CMDLINE] [KEY_CHECK]
> + [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA]
> mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
> [[^]MAY_EXEC]
> fsmagic:= hex value
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index a09d1a41a290..07116ff35c25 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -85,6 +85,7 @@ struct ima_rule_entry {
> } lsm[MAX_LSM_RULES];
> char *fsname;
> struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */
> + struct ima_rule_opt_list *data_source; /* Measure data from this source */
Argh, there are still some more instances of data_source sneaking into
this patch too early instead of waiting until the next patch.
> struct ima_template_desc *template;
> };
>
> @@ -479,6 +480,12 @@ static bool ima_match_rule_data(struct ima_rule_entry *rule,
>
> opt_list = rule->keyrings;
> break;
> + case CRITICAL_DATA:
> + if (!rule->data_source)
> + return true;
> +
> + opt_list = rule->data_source;
> + break;
I guess this case should unconditionally return true in this patch and
then the include this additional logic in the next patch.
Sorry, I missed these on my last review.
Tyler
> default:
> return false;
> }
> @@ -515,13 +522,19 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
> {
> int i;
>
> - if (func == KEY_CHECK) {
> - return (rule->flags & IMA_FUNC) && (rule->func == func) &&
> - ima_match_rule_data(rule, func_data, cred);
> - }
> if ((rule->flags & IMA_FUNC) &&
> (rule->func != func && func != POST_SETATTR))
> return false;
> +
> + switch (func) {
> + case KEY_CHECK:
> + case CRITICAL_DATA:
> + return ((rule->func == func) &&
> + ima_match_rule_data(rule, func_data, cred));
> + default:
> + break;
> + }
> +
> if ((rule->flags & IMA_MASK) &&
> (rule->mask != mask && func != POST_SETATTR))
> return false;
> @@ -1116,6 +1129,17 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
> if (ima_rule_contains_lsm_cond(entry))
> return false;
>
> + break;
> + case CRITICAL_DATA:
> + if (entry->action & ~(MEASURE | DONT_MEASURE))
> + return false;
> +
> + if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR))
> + return false;
> +
> + if (ima_rule_contains_lsm_cond(entry))
> + return false;
> +
> break;
> default:
> return false;
> @@ -1248,6 +1272,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
> else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) &&
> strcmp(args[0].from, "KEY_CHECK") == 0)
> entry->func = KEY_CHECK;
> + else if (strcmp(args[0].from, "CRITICAL_DATA") == 0)
> + entry->func = CRITICAL_DATA;
> else
> result = -EINVAL;
> if (!result)
> --
> 2.17.1
>
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