Ack: Re: [maverick/ti-omap4 CVE 1/1] ima: fix add LSM rule bug

[Herton Ronaldo Krzesinski]

On Wed, Feb 01, 2012 at 09:35:57AM +0000, Andy Whitcroft wrote:
> From: Mimi Zohar <zohar at linux.vnet.ibm.com>
> 
> If security_filter_rule_init() doesn't return a rule, then not everything
> is as fine as the return code implies.
> 
> This bug only occurs when the LSM (eg. SELinux) is disabled at runtime.
> 
> Adding an empty LSM rule causes ima_match_rules() to always succeed,
> ignoring any remaining rules.
> 
>  default IMA TCB policy:
>   # PROC_SUPER_MAGIC
>   dont_measure fsmagic=0x9fa0
>   # SYSFS_MAGIC
>   dont_measure fsmagic=0x62656572
>   # DEBUGFS_MAGIC
>   dont_measure fsmagic=0x64626720
>   # TMPFS_MAGIC
>   dont_measure fsmagic=0x01021994
>   # SECURITYFS_MAGIC
>   dont_measure fsmagic=0x73636673
> 
>   < LSM specific rule >
>   dont_measure obj_type=var_log_t
> 
>   measure func=BPRM_CHECK
>   measure func=FILE_MMAP mask=MAY_EXEC
>   measure func=FILE_CHECK mask=MAY_READ uid=0
> 
> Thus without the patch, with the boot parameters 'tcb selinux=0', adding
> the above 'dont_measure obj_type=var_log_t' rule to the default IMA TCB
> measurement policy, would result in nothing being measured.  The patch
> prevents the default TCB policy from being replaced.
> 
> Signed-off-by: Mimi Zohar <zohar at us.ibm.com>
> Cc: James Morris <jmorris at namei.org>
> Acked-by: Serge Hallyn <serge.hallyn at canonical.com>
> Cc: David Safford <safford at watson.ibm.com>
> Cc: <stable at kernel.org>
> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> 
> (cherry picked from commit 867c20265459d30a01b021a9c1e81fb4c5832aa9)
> CVE-2011-0006
> BugLink: http://bugs.launchpad.net/bugs/917808
> Signed-off-by: Andy Whitcroft <apw at canonical.com>
> ---
>  security/integrity/ima/ima_policy.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index aef8c0a..d661afb 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -253,6 +253,8 @@ static int ima_lsm_rule_init(struct ima_measure_rule_entry *entry,
>  	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
>  					   Audit_equal, args,
>  					   &entry->lsm[lsm_rule].rule);
> +	if (!entry->lsm[lsm_rule].rule)
> +		return -EINVAL;
>  	return result;
>  }
>  
> -- 
> 1.7.5.4
> 
> 
> -- 
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>