Re: [RFC][PATCH 7/7] ima: added new LSM conditions in the policy

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On Thursday, April 28, 2011 03:32:38 PM Mimi Zohar wrote:
> On Wed, 2011-04-27 at 14:34 +0200, Roberto Sassu wrote:
> > The new parameters 'fowner_user', 'fowner_role' and 'fowner_type' are new
> > LSM conditions that allow to measure inodes whose opened file descriptor
> > has the label given as a value.
> > 
> > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxx>
> 
> Nice. I really like the 'fowner_' prefix. If you don't object, I'll
> change the ima-appraisal keyword from 'owner' to 'fowner' as well.
> 

Hi Mimi

i agree about this change.

Thanks

Roberto Sassu


> Acked-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
> 
> thanks,
> 
> Mimi
> 
> > ---
> >  Documentation/ABI/testing/ima_policy |    7 ++++-
> >  security/integrity/ima/ima.h         |    4 +-
> >  security/integrity/ima/ima_api.c     |    4 +-
> >  security/integrity/ima/ima_main.c    |    4 +-
> >  security/integrity/ima/ima_policy.c  |   45 +++++++++++++++++++++++++++++----
> >  5 files changed, 51 insertions(+), 13 deletions(-)
> > 
> > diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
> > index 6cd6dae..ee49345 100644
> > --- a/Documentation/ABI/testing/ima_policy
> > +++ b/Documentation/ABI/testing/ima_policy
> > @@ -18,7 +18,8 @@ Description:
> >  		condition:= base | lsm
> >  			base:	[[func=] [mask=] [fsmagic=] [uid=]]
> >  			lsm:	[[subj_user=] [subj_role=] [subj_type=]
> > -				 [obj_user=] [obj_role=] [obj_type=]]
> > +				 [obj_user=] [obj_role=] [obj_type=]
> > +				 [fowner_user=] [fowner_role=] [fowner_type=]]
> > 
> >  		base: 	func:= [BPRM_CHECK][FILE_MMAP][FILE_CHECK]
> >  			mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC]
> > @@ -46,6 +47,10 @@ Description:
> >  		all files mmapped executable in file_mmap, and all files
> >  		open for read by root in do_filp_open.
> > 
> > +		LSM conditions starting with obj_ refer to security attributes
> > +		of inodes while those starting with fowner_ involve file
> > +		descriptors.
> > +
> >  		Examples of LSM specific definitions:
> > 
> >  		SELinux:
> > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> > index 08408bd..3a05625 100644
> > --- a/security/integrity/ima/ima.h
> > +++ b/security/integrity/ima/ima.h
> > @@ -110,7 +110,7 @@ struct ima_iint_cache {
> >  };
> > 
> >  /* LIM API function definitions */
> > -int ima_must_measure(struct inode *inode, int mask, int function);
> > +int ima_must_measure(struct file *file, int mask, int function);
> >  int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file);
> >  void ima_store_measurement(struct ima_iint_cache *iint, struct file *file,
> >  			   const unsigned char *filename);
> > @@ -128,7 +128,7 @@ struct ima_iint_cache *ima_iint_find(struct inode *inode);
> >  /* IMA policy related functions */
> >  enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK };
> > 
> > -int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask);
> > +int ima_match_policy(struct file *file, enum ima_hooks func, int mask);
> >  void ima_init_policy(void);
> >  void ima_update_policy(void);
> >  ssize_t ima_parse_add_rule(char *);
> > diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> > index da36d2c..d815392 100644
> > --- a/security/integrity/ima/ima_api.c
> > +++ b/security/integrity/ima/ima_api.c
> > @@ -108,11 +108,11 @@ err_out:
> >   * Return 0 to measure. For matching a DONT_MEASURE policy, no policy,
> >   * or other error, return an error code.
> >  */
> > -int ima_must_measure(struct inode *inode, int mask, int function)
> > +int ima_must_measure(struct file *file, int mask, int function)
> >  {
> >  	int must_measure;
> > 
> > -	must_measure = ima_match_policy(inode, function, mask);
> > +	must_measure = ima_match_policy(file, function, mask);
> >  	return must_measure ? 0 : -EACCES;
> >  }
> > 
> > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> > index 39d66dc..9eaca61 100644
> > --- a/security/integrity/ima/ima_main.c
> > +++ b/security/integrity/ima/ima_main.c
> > @@ -65,7 +65,7 @@ static void ima_rdwr_violation_check(struct file *file)
> >  		goto out;
> >  	}
> > 
> > -	rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
> > +	rc = ima_must_measure(file, MAY_READ, FILE_CHECK);
> >  	if (rc < 0)
> >  		goto out;
> > 
> > @@ -127,7 +127,7 @@ static int process_measurement(struct file *file, const unsigned char *filename,
> >  	if (!ima_initialized || !S_ISREG(inode->i_mode))
> >  		return 0;
> > 
> > -	rc = ima_must_measure(inode, mask, function);
> > +	rc = ima_must_measure(file, mask, function);
> >  	if (rc != 0)
> >  		return rc;
> >  retry:
> > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> > index d661afb..115c2e7 100644
> > --- a/security/integrity/ima/ima_policy.c
> > +++ b/security/integrity/ima/ima_policy.c
> > @@ -27,9 +27,10 @@
> > 
> >  enum ima_action { UNKNOWN = -1, DONT_MEASURE = 0, MEASURE };
> > 
> > -#define MAX_LSM_RULES 6
> > +#define MAX_LSM_RULES 9
> >  enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
> > -	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
> > +	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE,
> > +	LSM_FOWNER_USER, LSM_FOWNER_ROLE, LSM_FOWNER_TYPE
> >  };
> > 
> >  struct ima_measure_rule_entry {
> > @@ -96,9 +97,10 @@ __setup("ima_tcb", default_policy_setup);
> >   * Returns true on rule match, false on failure.
> >   */
> >  static bool ima_match_rules(struct ima_measure_rule_entry *rule,
> > -			    struct inode *inode, enum ima_hooks func, int mask)
> > +			    struct file *file, enum ima_hooks func, int mask)
> >  {
> >  	struct task_struct *tsk = current;
> > +	struct inode *inode = file->f_dentry->d_inode;
> >  	int i;
> > 
> >  	if ((rule->flags & IMA_FUNC) && rule->func != func)
> > @@ -112,7 +114,7 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
> >  		return false;
> >  	for (i = 0; i < MAX_LSM_RULES; i++) {
> >  		int rc = 0;
> > -		u32 osid, sid;
> > +		u32 osid, sid, fsid;
> > 
> >  		if (!rule->lsm[i].rule)
> >  			continue;
> > @@ -137,6 +139,15 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
> >  							Audit_equal,
> >  							rule->lsm[i].rule,
> >  							NULL);
> > +		case LSM_FOWNER_USER:
> > +		case LSM_FOWNER_ROLE:
> > +		case LSM_FOWNER_TYPE:
> > +			security_file_getsecid(file, &fsid);
> > +			rc = security_filter_rule_match(fsid,
> > +							rule->lsm[i].type,
> > +							Audit_equal,
> > +							rule->lsm[i].rule,
> > +							NULL);
> >  		default:
> >  			break;
> >  		}
> > @@ -159,14 +170,14 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
> >   * as elements in the list are never deleted, nor does the list
> >   * change.)
> >   */
> > -int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
> > +int ima_match_policy(struct file *file, enum ima_hooks func, int mask)
> >  {
> >  	struct ima_measure_rule_entry *entry;
> > 
> >  	list_for_each_entry(entry, ima_measure, list) {
> >  		bool rc;
> > 
> > -		rc = ima_match_rules(entry, inode, func, mask);
> > +		rc = ima_match_rules(entry, file, func, mask);
> >  		if (rc)
> >  			return entry->action;
> >  	}
> > @@ -222,6 +233,7 @@ enum {
> >  	Opt_measure = 1, Opt_dont_measure,
> >  	Opt_obj_user, Opt_obj_role, Opt_obj_type,
> >  	Opt_subj_user, Opt_subj_role, Opt_subj_type,
> > +	Opt_fowner_user, Opt_fowner_role, Opt_fowner_type,
> >  	Opt_func, Opt_mask, Opt_fsmagic, Opt_uid
> >  };
> > 
> > @@ -234,6 +246,9 @@ static match_table_t policy_tokens = {
> >  	{Opt_subj_user, "subj_user=%s"},
> >  	{Opt_subj_role, "subj_role=%s"},
> >  	{Opt_subj_type, "subj_type=%s"},
> > +	{Opt_fowner_user, "fowner_user=%s"},
> > +	{Opt_fowner_role, "fowner_role=%s"},
> > +	{Opt_fowner_type, "fowner_type=%s"},
> >  	{Opt_func, "func=%s"},
> >  	{Opt_mask, "mask=%s"},
> >  	{Opt_fsmagic, "fsmagic=%s"},
> > @@ -407,6 +422,24 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
> >  						   LSM_SUBJ_TYPE,
> >  						   AUDIT_SUBJ_TYPE);
> >  			break;
> > +		case Opt_fowner_user:
> > +			ima_log_string(ab, "fowner_user", args[0].from);
> > +			result = ima_lsm_rule_init(entry, args[0].from,
> > +						   LSM_FOWNER_USER,
> > +						   AUDIT_SUBJ_USER);
> > +			break;
> > +		case Opt_fowner_role:
> > +			ima_log_string(ab, "fowner_role", args[0].from);
> > +			result = ima_lsm_rule_init(entry, args[0].from,
> > +						   LSM_FOWNER_ROLE,
> > +						   AUDIT_SUBJ_ROLE);
> > +			break;
> > +		case Opt_fowner_type:
> > +			ima_log_string(ab, "fowner_type", args[0].from);
> > +			result = ima_lsm_rule_init(entry, args[0].from,
> > +						   LSM_FOWNER_TYPE,
> > +						   AUDIT_SUBJ_TYPE);
> > +			break;
> >  		case Opt_err:
> >  			ima_log_string(ab, "UNKNOWN", p);
> >  			result = -EINVAL;
> 
> 
> 
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