Commit 2e962e2f authored Nov 23, 2016 by Vishal Goel Committed by Casey Schaufler Jan 10, 2017

SMACK: Add new lock for adding entry in smack master list



"smk_set_access()" function adds a new rule entry in subject label specific
list(rule_list) and in global rule list(smack_rule_list) both. Mutex lock
(rule_lock) is used to avoid simultaneous updates. But this lock is subject
label specific lock. If 2 processes tries to add different rules(i.e with
different subject labels) simultaneously, then both the processes can take
the "rule_lock" respectively. So it will cause a problem while adding
entries in master rule list.
Now a new mutex lock(smack_master_list_lock) has been taken to add entry in
smack_rule_list to avoid simultaneous updates of different rules.

Signed-off-by: Vishal Goel <vishal.goel@samsung.com>
Signed-off-by: Himanshu Shukla <himanshu.sh@samsung.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

parent 0c96d1f5

security/smack/smackfs.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -67,6 +67,7 @@ enum smk_inos {
		/*
		* List locks
		*/
		static DEFINE_MUTEX(smack_master_list_lock);
		static DEFINE_MUTEX(smack_cipso_lock);
		static DEFINE_MUTEX(smack_ambient_lock);
		static DEFINE_MUTEX(smk_net4addr_lock);
		@@ -262,12 +263,16 @@ static int smk_set_access(struct smack_parsed_rule *srp,
		* it needs to get added for reporting.
		*/
		if (global) {
		mutex_unlock(rule_lock);
		smlp = kzalloc(sizeof(*smlp), GFP_KERNEL);
		if (smlp != NULL) {
		smlp->smk_rule = sp;
		mutex_lock(&smack_master_list_lock);
		list_add_rcu(&smlp->list, &smack_rule_list);
		mutex_unlock(&smack_master_list_lock);
		} else
		rc = -ENOMEM;
		return rc;
		}
		}

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