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From: Tyler Hicks <tyhicks@linux.microsoft.com>
To: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	James Morris <jmorris@namei.org>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	Prakhar Srivastava <prsriva02@gmail.com>,
	linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org
Subject: Re: [PATCH v2 09/11] ima: Move validation of the keyrings conditional into ima_validate_rule()
Date: Mon, 29 Jun 2020 09:16:14 -0500
Message-ID: <20200629141614.GD4694@sequoia> (raw)
In-Reply-To: <0e7012e7-e1df-466d-9d51-a691f779570a@linux.microsoft.com>

On 2020-06-27 16:49:46, Lakshmi Ramasubramanian wrote:
> 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.

It actually doesn't do any additional validation of other IMA hooks at
this time. That check on entry->flags is an allowlist of every possible
conditional flag except IMA_KEYRINGS. The ima_parse_rule() function is
already validating all of these conditional flags.

Tyler

> 
>  -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;
> > 

  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-26 22:38 [PATCH v2 00/11] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 01/11] ima: Have the LSM free its audit rule Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 02/11] ima: Free the entire rule when deleting a list of rules Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 03/11] ima: Free the entire rule if it fails to parse Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 04/11] ima: Fail rule parsing when buffer hook functions have an invalid action Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 05/11] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond Tyler Hicks
2020-06-27 23:40   ` Lakshmi Ramasubramanian
2020-06-26 22:38 ` [PATCH v2 06/11] ima: Fail rule parsing when the KEY_CHECK " Tyler Hicks
2020-06-27 23:39   ` Lakshmi Ramasubramanian
2020-06-26 22:38 ` [PATCH v2 07/11] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 08/11] ima: Use correct type for " Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 09/11] ima: Move validation of the keyrings conditional into ima_validate_rule() Tyler Hicks
2020-06-27 23:49   ` Lakshmi Ramasubramanian
2020-06-29 14:16     ` Tyler Hicks [this message]
2020-06-30 23:07   ` Mimi Zohar
2020-07-02 22:16     ` Tyler Hicks
2020-07-03 14:15       ` Mimi Zohar
2020-07-06 13:18         ` Tyler Hicks
2020-07-07  3:18           ` Mimi Zohar
2020-06-26 22:38 ` [PATCH v2 10/11] ima: Use the common function to detect LSM conditionals in a rule Tyler Hicks
2020-06-26 22:39 ` [PATCH v2 11/11] ima: Support additional conditionals in the KEXEC_CMDLINE hook function Tyler Hicks
2020-06-28  0:03   ` Lakshmi Ramasubramanian
2020-07-01  8:04   ` Dave Young
2020-07-01 14:38     ` Tyler Hicks
2020-07-01  0:29 ` [PATCH v2 00/11] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Mimi Zohar

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