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SubjectRe: [PATCH v2 09/11] ima: Move validation of the keyrings conditional into ima_validate_rule()
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On 6/26/20 3:38 PM, Tyler Hicks wrote:

> Use ima_validate_rule() to ensure that the combination of a hook
> function and the keyrings conditional is valid and that the keyrings
> conditional is not specified without an explicit KEY_CHECK func
> conditional. This is a code cleanup and has no user-facing change.

In addition to checking for func=KEY_CHECK and the keyrings conditional,
the patch also validates the flags for other IMA hooks (such as
KEXEC_KERNEL_CHECK, POLICY_CHECK, etc.) Would be good to mention that in
the patch description.

-lakshmi

>
> Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
> ---
>
> * v2
> - Allowed IMA_DIGSIG_REQUIRED, IMA_PERMIT_DIRECTIO,
> IMA_MODSIG_ALLOWED, and IMA_CHECK_BLACKLIST conditionals to be
> present in the rule entry flags for non-buffer hook functions.
>
> security/integrity/ima/ima_policy.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 8cdca2399d59..43d49ad958fb 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -1000,6 +1000,15 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
> case KEXEC_KERNEL_CHECK:
> case KEXEC_INITRAMFS_CHECK:
> case POLICY_CHECK:
> + if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
> + IMA_UID | IMA_FOWNER | IMA_FSUUID |
> + IMA_INMASK | IMA_EUID | IMA_PCR |
> + IMA_FSNAME | IMA_DIGSIG_REQUIRED |
> + IMA_PERMIT_DIRECTIO |
> + IMA_MODSIG_ALLOWED |
> + IMA_CHECK_BLACKLIST))
> + return false;
> +
> break;
> case KEXEC_CMDLINE:
> if (entry->action & ~(MEASURE | DONT_MEASURE))
> @@ -1027,7 +1036,8 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
> default:
> return false;
> }
> - }
> + } else if (entry->flags & IMA_KEYRINGS)
> + return false;
>
> return true;
> }
> @@ -1209,7 +1219,6 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
> keyrings_len = strlen(args[0].from) + 1;
>
> if ((entry->keyrings) ||
> - (entry->func != KEY_CHECK) ||
> (keyrings_len < 2)) {
> result = -EINVAL;
> break;
>

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