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authorCasey Schaufler <casey@schaufler-ca.com>2011-02-08 16:36:24 -0800
committerJames Morris <jmorris@namei.org>2011-02-09 18:50:23 +1100
commit0e0a070d3a47d279de66e08244769556deae2eee (patch)
tree8d9c07464833076a40c1d95dd2f8f33716509290 /security
parent821404434f3324bf23f545050ff64055a149766e (diff)
Smack: correct behavior in the mmap hook
The mmap policy enforcement was not properly handling the interaction between the global and local rule lists. Instead of going through one and then the other, which missed the important case where a rule specified that there should be no access, combine the access limitations where there is a rule in each list. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security')
-rw-r--r--security/smack/smack_lsm.c85
1 files changed, 49 insertions, 36 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 123a499ded37..92cb71507f5b 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1110,38 +1110,6 @@ static int smack_file_fcntl(struct file *file, unsigned int cmd,
}
/**
- * smk_mmap_list_check - the mmap check
- * @sub: subject label
- * @obj: object label
- * @access: access mode
- * @local: the task specific rule list
- *
- * Returns 0 if acces is permitted, -EACCES otherwise
- */
-static int smk_mmap_list_check(char *sub, char *obj, int access,
- struct list_head *local)
-{
- int may;
-
- /*
- * If there is not a global rule that
- * allows access say no.
- */
- may = smk_access_entry(sub, obj, &smack_rule_list);
- if (may == -ENOENT || (may & access) != access)
- return -EACCES;
- /*
- * If there is a task local rule that
- * denies access say no.
- */
- may = smk_access_entry(sub, obj, local);
- if (may != -ENOENT && (may & access) != access)
- return -EACCES;
-
- return 0;
-}
-
-/**
* smack_file_mmap :
* Check permissions for a mmap operation. The @file may be NULL, e.g.
* if mapping anonymous memory.
@@ -1160,8 +1128,12 @@ static int smack_file_mmap(struct file *file,
struct task_smack *tsp;
char *sp;
char *msmack;
+ char *osmack;
struct inode_smack *isp;
struct dentry *dp;
+ int may;
+ int mmay;
+ int tmay;
int rc;
/* do DAC check on address space usage */
@@ -1199,16 +1171,57 @@ static int smack_file_mmap(struct file *file,
list_for_each_entry_rcu(srp, &smack_rule_list, list) {
if (srp->smk_subject != sp)
continue;
+
+ osmack = srp->smk_object;
/*
* Matching labels always allows access.
*/
- if (msmack == srp->smk_object)
+ if (msmack == osmack)
+ continue;
+ /*
+ * If there is a matching local rule take
+ * that into account as well.
+ */
+ may = smk_access_entry(srp->smk_subject, osmack,
+ &tsp->smk_rules);
+ if (may == -ENOENT)
+ may = srp->smk_access;
+ else
+ may &= srp->smk_access;
+ /*
+ * If may is zero the SMACK64MMAP subject can't
+ * possibly have less access.
+ */
+ if (may == 0)
continue;
- rc = smk_mmap_list_check(msmack, srp->smk_object,
- srp->smk_access, &tsp->smk_rules);
- if (rc != 0)
+ /*
+ * Fetch the global list entry.
+ * If there isn't one a SMACK64MMAP subject
+ * can't have as much access as current.
+ */
+ mmay = smk_access_entry(msmack, osmack, &smack_rule_list);
+ if (mmay == -ENOENT) {
+ rc = -EACCES;
break;
+ }
+ /*
+ * If there is a local entry it modifies the
+ * potential access, too.
+ */
+ tmay = smk_access_entry(msmack, osmack, &tsp->smk_rules);
+ if (tmay != -ENOENT)
+ mmay &= tmay;
+
+ /*
+ * If there is any access available to current that is
+ * not available to a SMACK64MMAP subject
+ * deny access.
+ */
+ if ((may | mmay) != may) {
+ rc = -EACCES;
+ break;
+ }
}
rcu_read_unlock();

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