Linux-Integrity Archive on lore.kernel.org
 help / color / Atom feed
From: Tyler Hicks <tyhicks@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	James Morris <jmorris@namei.org>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	Lakshmi Ramasubramanian <nramas@linux.microsoft.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: Thu, 2 Jul 2020 17:16:56 -0500
Message-ID: <20200702221656.GH4694@sequoia> (raw)
In-Reply-To: <1593558449.5057.12.camel@linux.ibm.com>

On 2020-06-30 19:07:29, Mimi Zohar wrote:
> On Fri, 2020-06-26 at 17:38 -0500, 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.
> > 
> > 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))
> 
> Other than KEYRINGS, this patch should continue to behave the same.
>  However, this list gives the impressions that all of these flags are
> permitted on all of the above flags, which isn't true.
> 
> For example, both IMA_MODSIG_ALLOWED & IMA_CHECK_BLACKLIST are limited
> to appended signatures, meaning KERNEL_CHECK and KEXEC_KERNEL_CHECK.

Just to clarify, are both IMA_MODSIG_ALLOWED and IMA_CHECK_BLACKLIST
limited to KEXEC_KERNEL_CHECK, KEXEC_INITRAMFS_CHECK, and MODULE_CHECK?
That's what ima_hook_supports_modsig() suggests.

>  Both should only be allowed on APPRAISE action rules.

For completeness, it looks like DONT_APPRAISE should not be allowed.

> IMA_PCR should be limited to MEASURE action rules.

It looks like DONT_MEASURE should not be allowed.

> IMA_DIGSIG_REQUIRED should be limited to APPRAISE action rules.

It looks like DONT_APPRAISE should not be allowed.

> 
> > +				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;
> 
> IMA_MODSIG_ALLOWED and IMA_CHECK_BLACKLIST need to be added here as
> well.

That makes sense.

Tyler

> 
> Mimi
> 
> >  
> >  	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
2020-06-30 23:07   ` Mimi Zohar
2020-07-02 22:16     ` Tyler Hicks [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200702221656.GH4694@sequoia \
    --to=tyhicks@linux.microsoft.com \
    --cc=dmitry.kasatkin@gmail.com \
    --cc=jmorris@namei.org \
    --cc=linux-integrity@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=nramas@linux.microsoft.com \
    --cc=prsriva02@gmail.com \
    --cc=serge@hallyn.com \
    --cc=zohar@linux.ibm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Integrity Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-integrity/0 linux-integrity/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-integrity linux-integrity/ https://lore.kernel.org/linux-integrity \
		linux-integrity@vger.kernel.org
	public-inbox-index linux-integrity

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-integrity


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git