Merge branch 'smack-for-4.2-stacked' of https://github.com/cschaufler/smack-next into next

Documentation/security/Smack.txt

@@ -206,11 +206,11 @@ netlabel
 	label. The format accepted on write is:
 		"%d.%d.%d.%d label" or "%d.%d.%d.%d/%d label".
 onlycap
-	This contains the label processes must have for CAP_MAC_ADMIN
+	This contains labels processes must have for CAP_MAC_ADMIN
 	and CAP_MAC_OVERRIDE to be effective. If this file is empty
 	these capabilities are effective at for processes with any
-	label. The value is set by writing the desired label to the
-	file or cleared by writing "-" to the file.
+	label. The values are set by writing the desired labels, separated
+	by spaces, to the file or cleared by writing "-" to the file.
 ptrace
 	This is used to define the current ptrace policy
 	0 - default: this is the policy that relies on Smack access rules.

security/smack/smack.h

@@ -138,6 +138,11 @@ struct smk_port_label {
 	struct smack_known	*smk_out;	/* outgoing label */
 };
 
+struct smack_onlycap {
+	struct list_head	list;
+	struct smack_known	*smk_label;
+};
+
 /*
  * Mount options
  */
@@ -249,6 +254,7 @@ int smk_netlbl_mls(int, char *, struct netlbl_lsm_secattr *, int);
 struct smack_known *smk_import_entry(const char *, int);
 void smk_insert_entry(struct smack_known *skp);
 struct smack_known *smk_find_entry(const char *);
+int smack_privileged(int cap);
 
 /*
  * Shared data.
@@ -257,7 +263,6 @@ extern int smack_enabled;
 extern int smack_cipso_direct;
 extern int smack_cipso_mapped;
 extern struct smack_known *smack_net_ambient;
-extern struct smack_known *smack_onlycap;
 extern struct smack_known *smack_syslog_label;
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 extern struct smack_known *smack_unconfined;
@@ -276,6 +281,9 @@ extern struct mutex	smack_known_lock;
 extern struct list_head smack_known_list;
 extern struct list_head smk_netlbladdr_list;
 
+extern struct mutex     smack_onlycap_lock;
+extern struct list_head smack_onlycap_list;
+
 #define SMACK_HASH_SLOTS 16
 extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
 
@@ -331,21 +339,6 @@ static inline struct smack_known *smk_of_current(void)
 	return smk_of_task(current_security());
 }
 
-/*
- * Is the task privileged and allowed to be privileged
- * by the onlycap rule.
- */
-static inline int smack_privileged(int cap)
-{
-	struct smack_known *skp = smk_of_current();
-
-	if (!capable(cap))
-		return 0;
-	if (smack_onlycap == NULL || smack_onlycap == skp)
-		return 1;
-	return 0;
-}
-
 /*
  * logging functions
  */

security/smack/smack_access.c

@@ -425,7 +425,7 @@ void smk_insert_entry(struct smack_known *skp)
  * @string: a text string that might be a Smack label
  *
  * Returns a pointer to the entry in the label list that
- * matches the passed string.
+ * matches the passed string or NULL if not found.
  */
 struct smack_known *smk_find_entry(const char *string)
 {
@@ -448,7 +448,7 @@ struct smack_known *smk_find_entry(const char *string)
  * @string: a text string that might contain a Smack label
  * @len: the maximum size, or zero if it is NULL terminated.
  *
- * Returns a pointer to the clean label, or NULL
+ * Returns a pointer to the clean label or an error code.
  */
 char *smk_parse_smack(const char *string, int len)
 {
@@ -464,7 +464,7 @@ char *smk_parse_smack(const char *string, int len)
 	 * including /smack/cipso and /smack/cipso2
 	 */
 	if (string[0] == '-')
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	for (i = 0; i < len; i++)
 		if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
@@ -472,11 +472,13 @@ char *smk_parse_smack(const char *string, int len)
 			break;
 
 	if (i == 0 || i >= SMK_LONGLABEL)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	smack = kzalloc(i + 1, GFP_KERNEL);
-	if (smack != NULL)
-		strncpy(smack, string, i);
+	if (smack == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	strncpy(smack, string, i);
 
 	return smack;
 }
@@ -523,7 +525,8 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
  * @len: the maximum size, or zero if it is NULL terminated.
  *
  * Returns a pointer to the entry in the label list that
- * matches the passed string, adding it if necessary.
+ * matches the passed string, adding it if necessary,
+ * or an error code.
  */
 struct smack_known *smk_import_entry(const char *string, int len)
 {
@@ -533,8 +536,8 @@ struct smack_known *smk_import_entry(const char *string, int len)
 	int rc;
 
 	smack = smk_parse_smack(string, len);
-	if (smack == NULL)
-		return NULL;
+	if (IS_ERR(smack))
+		return ERR_CAST(smack);
 
 	mutex_lock(&smack_known_lock);
 
@@ -543,8 +546,10 @@ struct smack_known *smk_import_entry(const char *string, int len)
 		goto freeout;
 
 	skp = kzalloc(sizeof(*skp), GFP_KERNEL);
-	if (skp == NULL)
+	if (skp == NULL) {
+		skp = ERR_PTR(-ENOMEM);
 		goto freeout;
+	}
 
 	skp->smk_known = smack;
 	skp->smk_secid = smack_next_secid++;
@@ -577,7 +582,7 @@ struct smack_known *smk_import_entry(const char *string, int len)
 	 * smk_netlbl_mls failed.
 	 */
 	kfree(skp);
-	skp = NULL;
+	skp = ERR_PTR(rc);
 freeout:
 	kfree(smack);
 unlockout:
@@ -612,3 +617,44 @@ struct smack_known *smack_from_secid(const u32 secid)
 	rcu_read_unlock();
 	return &smack_known_invalid;
 }
+
+/*
+ * Unless a process is running with one of these labels
+ * even having CAP_MAC_OVERRIDE isn't enough to grant
+ * privilege to violate MAC policy. If no labels are
+ * designated (the empty list case) capabilities apply to
+ * everyone.
+ */
+LIST_HEAD(smack_onlycap_list);
+DEFINE_MUTEX(smack_onlycap_lock);
+
+/*
+ * Is the task privileged and allowed to be privileged
+ * by the onlycap rule.
+ *
+ * Returns 1 if the task is allowed to be privileged, 0 if it's not.
+ */
+int smack_privileged(int cap)
+{
+	struct smack_known *skp = smk_of_current();
+	struct smack_onlycap *sop;
+
+	if (!capable(cap))
+		return 0;
+
+	rcu_read_lock();
+	if (list_empty(&smack_onlycap_list)) {
+		rcu_read_unlock();
+		return 1;
+	}
+
+	list_for_each_entry_rcu(sop, &smack_onlycap_list, list) {
+		if (sop->smk_label == skp) {
+			rcu_read_unlock();
+			return 1;
+		}
+	}
+	rcu_read_unlock();
+
+	return 0;
+}

security/smack/smack_lsm.c

@@ -245,8 +245,8 @@ static int smk_bu_credfile(const struct cred *cred, struct file *file,
  * @ip: a pointer to the inode
  * @dp: a pointer to the dentry
  *
- * Returns a pointer to the master list entry for the Smack label
- * or NULL if there was no label to fetch.
+ * Returns a pointer to the master list entry for the Smack label,
+ * NULL if there was no label to fetch, or an error code.
  */
 static struct smack_known *smk_fetch(const char *name, struct inode *ip,
 					struct dentry *dp)
@@ -256,14 +256,18 @@ static struct smack_known *smk_fetch(const char *name, struct inode *ip,
 	struct smack_known *skp = NULL;
 
 	if (ip->i_op->getxattr == NULL)
-		return NULL;
+		return ERR_PTR(-EOPNOTSUPP);
 
 	buffer = kzalloc(SMK_LONGLABEL, GFP_KERNEL);
 	if (buffer == NULL)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	rc = ip->i_op->getxattr(dp, name, buffer, SMK_LONGLABEL);
-	if (rc > 0)
+	if (rc < 0)
+		skp = ERR_PTR(rc);
+	else if (rc == 0)
+		skp = NULL;
+	else
 		skp = smk_import_entry(buffer, rc);
 
 	kfree(buffer);
@@ -605,40 +609,44 @@ static int smack_sb_kern_mount(struct super_block *sb, int flags, void *data)
 		if (strncmp(op, SMK_FSHAT, strlen(SMK_FSHAT)) == 0) {
 			op += strlen(SMK_FSHAT);
 			skp = smk_import_entry(op, 0);
-			if (skp != NULL) {
-				sp->smk_hat = skp;
-				specified = 1;
-			}
+			if (IS_ERR(skp))
+				return PTR_ERR(skp);
+			sp->smk_hat = skp;
+			specified = 1;
+
 		} else if (strncmp(op, SMK_FSFLOOR, strlen(SMK_FSFLOOR)) == 0) {
 			op += strlen(SMK_FSFLOOR);
 			skp = smk_import_entry(op, 0);
-			if (skp != NULL) {
-				sp->smk_floor = skp;
-				specified = 1;
-			}
+			if (IS_ERR(skp))
+				return PTR_ERR(skp);
+			sp->smk_floor = skp;
+			specified = 1;
+
 		} else if (strncmp(op, SMK_FSDEFAULT,
 				   strlen(SMK_FSDEFAULT)) == 0) {
 			op += strlen(SMK_FSDEFAULT);
 			skp = smk_import_entry(op, 0);
-			if (skp != NULL) {
-				sp->smk_default = skp;
-				specified = 1;
-			}
+			if (IS_ERR(skp))
+				return PTR_ERR(skp);
+			sp->smk_default = skp;
+			specified = 1;
+
 		} else if (strncmp(op, SMK_FSROOT, strlen(SMK_FSROOT)) == 0) {
 			op += strlen(SMK_FSROOT);
 			skp = smk_import_entry(op, 0);
-			if (skp != NULL) {
-				sp->smk_root = skp;
-				specified = 1;
-			}
+			if (IS_ERR(skp))
+				return PTR_ERR(skp);
+			sp->smk_root = skp;
+			specified = 1;
+
 		} else if (strncmp(op, SMK_FSTRANS, strlen(SMK_FSTRANS)) == 0) {
 			op += strlen(SMK_FSTRANS);
 			skp = smk_import_entry(op, 0);
-			if (skp != NULL) {
-				sp->smk_root = skp;
-				transmute = 1;
-				specified = 1;
-			}
+			if (IS_ERR(skp))
+				return PTR_ERR(skp);
+			sp->smk_root = skp;
+			transmute = 1;
+			specified = 1;
 		}
 	}
 
@@ -1118,7 +1126,9 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
 
 	if (rc == 0 && check_import) {
 		skp = size ? smk_import_entry(value, size) : NULL;
-		if (skp == NULL || (check_star &&
+		if (IS_ERR(skp))
+			rc = PTR_ERR(skp);
+		else if (skp == NULL || (check_star &&
 		    (skp == &smack_known_star || skp == &smack_known_web)))
 			rc = -EINVAL;
 	}
@@ -1158,19 +1168,19 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
 
 	if (strcmp(name, XATTR_NAME_SMACK) == 0) {
 		skp = smk_import_entry(value, size);
-		if (skp != NULL)
+		if (!IS_ERR(skp))
 			isp->smk_inode = skp;
 		else
 			isp->smk_inode = &smack_known_invalid;
 	} else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
 		skp = smk_import_entry(value, size);
-		if (skp != NULL)
+		if (!IS_ERR(skp))
 			isp->smk_task = skp;
 		else
 			isp->smk_task = &smack_known_invalid;
 	} else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {
 		skp = smk_import_entry(value, size);
-		if (skp != NULL)
+		if (!IS_ERR(skp))
 			isp->smk_mmap = skp;
 		else
 			isp->smk_mmap = &smack_known_invalid;
@@ -1658,6 +1668,9 @@ static int smack_file_receive(struct file *file)
 	struct smk_audit_info ad;
 	struct inode *inode = file_inode(file);
 
+	if (unlikely(IS_PRIVATE(inode)))
+		return 0;
+
 	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
 	smk_ad_setfield_u_fs_path(&ad, file->f_path);
 	/*
@@ -2400,8 +2413,8 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
 		return -EINVAL;
 
 	skp = smk_import_entry(value, size);
-	if (skp == NULL)
-		return -EINVAL;
+	if (IS_ERR(skp))
+		return PTR_ERR(skp);
 
 	if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
 		nsp->smk_inode = skp;
@@ -3174,7 +3187,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 		 */
 		dp = dget(opt_dentry);
 		skp = smk_fetch(XATTR_NAME_SMACK, inode, dp);
-		if (skp != NULL)
+		if (!IS_ERR_OR_NULL(skp))
 			final = skp;
 
 		/*
@@ -3211,11 +3224,14 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 		 * Don't let the exec or mmap label be "*" or "@".
 		 */
 		skp = smk_fetch(XATTR_NAME_SMACKEXEC, inode, dp);
-		if (skp == &smack_known_star || skp == &smack_known_web)
+		if (IS_ERR(skp) || skp == &smack_known_star ||
+		    skp == &smack_known_web)
 			skp = NULL;
 		isp->smk_task = skp;
+
 		skp = smk_fetch(XATTR_NAME_SMACKMMAP, inode, dp);
-		if (skp == &smack_known_star || skp == &smack_known_web)
+		if (IS_ERR(skp) || skp == &smack_known_star ||
+		    skp == &smack_known_web)
 			skp = NULL;
 		isp->smk_mmap = skp;
 
@@ -3299,8 +3315,8 @@ static int smack_setprocattr(struct task_struct *p, char *name,
 		return -EINVAL;
 
 	skp = smk_import_entry(value, size);
-	if (skp == NULL)
-		return -EINVAL;
+	if (IS_ERR(skp))
+		return PTR_ERR(skp);
 
 	/*
 	 * No process is ever allowed the web ("@") label.
@@ -4075,8 +4091,10 @@ static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
 		return -EINVAL;
 
 	skp = smk_import_entry(rulestr, 0);
-	if (skp)
-		*rule = skp->smk_known;
+	if (IS_ERR(skp))
+		return PTR_ERR(skp);
+
+	*rule = skp->smk_known;
 
 	return 0;
 }

security/smack/smackfs.c

@@ -87,16 +87,6 @@ int smack_cipso_direct = SMACK_CIPSO_DIRECT_DEFAULT;
  */
 int smack_cipso_mapped = SMACK_CIPSO_MAPPED_DEFAULT;
 
-/*
- * Unless a process is running with this label even
- * having CAP_MAC_OVERRIDE isn't enough to grant
- * privilege to violate MAC policy. If no label is
- * designated (the NULL case) capabilities apply to
- * everyone. It is expected that the hat (^) label
- * will be used if any label is used.
- */
-struct smack_known *smack_onlycap;
-
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 /*
  * Allow one label to be unconfined. This is for
@@ -338,8 +328,7 @@ static int smk_perm_from_str(const char *string)
  * @import: if non-zero, import labels
  * @len: label length limit
  *
- * Returns 0 on success, -EINVAL on failure and -ENOENT when either subject
- * or object is missing.
+ * Returns 0 on success, appropriate error code on failure.
  */
 static int smk_fill_rule(const char *subject, const char *object,
 				const char *access1, const char *access2,
@@ -351,16 +340,16 @@ static int smk_fill_rule(const char *subject, const char *object,
 
 	if (import) {
 		rule->smk_subject = smk_import_entry(subject, len);
-		if (rule->smk_subject == NULL)
-			return -EINVAL;
+		if (IS_ERR(rule->smk_subject))
+			return PTR_ERR(rule->smk_subject);
 
 		rule->smk_object = smk_import_entry(object, len);
-		if (rule->smk_object == NULL)
-			return -EINVAL;
+		if (IS_ERR(rule->smk_object))
+			return PTR_ERR(rule->smk_object);
 	} else {
 		cp = smk_parse_smack(subject, len);
-		if (cp == NULL)
-			return -EINVAL;
+		if (IS_ERR(cp))
+			return PTR_ERR(cp);
 		skp = smk_find_entry(cp);
 		kfree(cp);
 		if (skp == NULL)
@@ -368,8 +357,8 @@ static int smk_fill_rule(const char *subject, const char *object,
 		rule->smk_subject = skp;
 
 		cp = smk_parse_smack(object, len);
-		if (cp == NULL)
-			return -EINVAL;
+		if (IS_ERR(cp))
+			return PTR_ERR(cp);
 		skp = smk_find_entry(cp);
 		kfree(cp);
 		if (skp == NULL)
@@ -412,7 +401,7 @@ static int smk_parse_rule(const char *data, struct smack_parsed_rule *rule,
  * @import: if non-zero, import labels
  * @tokens: numer of substrings expected in data
  *
- * Returns number of processed bytes on success, -1 on failure.
+ * Returns number of processed bytes on success, -ERRNO on failure.
  */
 static ssize_t smk_parse_long_rule(char *data, struct smack_parsed_rule *rule,
 				int import, int tokens)
@@ -431,7 +420,7 @@ static ssize_t smk_parse_long_rule(char *data, struct smack_parsed_rule *rule,
 
 		if (data[cnt] == '\0')
 			/* Unexpected end of data */
-			return -1;
+			return -EINVAL;
 
 		tok[i] = data + cnt;
 
@@ -529,14 +518,14 @@ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf,
 	while (cnt < count) {
 		if (format == SMK_FIXED24_FMT) {
 			rc = smk_parse_rule(data, &rule, 1);
-			if (rc != 0) {
-				rc = -EINVAL;
+			if (rc < 0)
 				goto out;
-			}
 			cnt = count;
 		} else {
 			rc = smk_parse_long_rule(data + cnt, &rule, 1, tokens);
-			if (rc <= 0) {
+			if (rc < 0)
+				goto out;
+			if (rc == 0) {
 				rc = -EINVAL;
 				goto out;
 			}
@@ -567,23 +556,17 @@ static void *smk_seq_start(struct seq_file *s, loff_t *pos,
 				struct list_head *head)
 {
 	struct list_head *list;
+	int i = *pos;
+
+	rcu_read_lock();
+	for (list = rcu_dereference(list_next_rcu(head));
+		list != head;
+		list = rcu_dereference(list_next_rcu(list))) {
+		if (i-- == 0)
+			return list;
+	}
 
-	/*
-	 * This is 0 the first time through.
-	 */
-	if (s->index == 0)
-		s->private = head;
-
-	if (s->private == NULL)
-		return NULL;
-
-	list = s->private;
-	if (list_empty(list))
-		return NULL;
-
-	if (s->index == 0)
-		return list->next;
-	return list;
+	return NULL;
 }
 
 static void *smk_seq_next(struct seq_file *s, void *v, loff_t *pos,
@@ -591,17 +574,15 @@ static void *smk_seq_next(struct seq_file *s, void *v, loff_t *pos,
 {
 	struct list_head *list = v;
 
-	if (list_is_last(list, head)) {
-		s->private = NULL;
-		return NULL;
-	}
-	s->private = list->next;
-	return list->next;
+	++*pos;
+	list = rcu_dereference(list_next_rcu(list));
+
+	return (list == head) ? NULL : list;
 }
 
 static void smk_seq_stop(struct seq_file *s, void *v)
 {
-	/* No-op */
+	rcu_read_unlock();
 }
 
 static void smk_rule_show(struct seq_file *s, struct smack_rule *srp, int max)
@@ -661,7 +642,7 @@ static int load_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
 	struct smack_master_list *smlp =
-		 list_entry(list, struct smack_master_list, list);
+		list_entry_rcu(list, struct smack_master_list, list);
 
 	smk_rule_show(s, smlp->smk_rule, SMK_LABELLEN);
 
@@ -809,7 +790,7 @@ static int cipso_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head  *list = v;
 	struct smack_known *skp =
-		 list_entry(list, struct smack_known, list);
+		list_entry_rcu(list, struct smack_known, list);
 	struct netlbl_lsm_catmap *cmp = skp->smk_netlabel.attr.mls.cat;
 	char sep = '/';
 	int i;
@@ -915,8 +896,10 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
 	mutex_lock(&smack_cipso_lock);
 
 	skp = smk_import_entry(rule, 0);
-	if (skp == NULL)
+	if (IS_ERR(skp)) {
+		rc = PTR_ERR(skp);
 		goto out;
+	}
 
 	if (format == SMK_FIXED24_FMT)
 		rule += SMK_LABELLEN;
@@ -998,7 +981,7 @@ static int cipso2_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head  *list = v;
 	struct smack_known *skp =
-		 list_entry(list, struct smack_known, list);
+		list_entry_rcu(list, struct smack_known, list);
 	struct netlbl_lsm_catmap *cmp = skp->smk_netlabel.attr.mls.cat;
 	char sep = '/';
 	int i;
@@ -1082,7 +1065,7 @@ static int netlbladdr_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
 	struct smk_netlbladdr *skp =
-			 list_entry(list, struct smk_netlbladdr, list);
+			list_entry_rcu(list, struct smk_netlbladdr, list);
 	unsigned char *hp = (char *) &skp->smk_host.sin_addr.s_addr;
 	int maskn;
 	u32 temp_mask = be32_to_cpu(skp->smk_mask.s_addr);
@@ -1237,8 +1220,8 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 	 */
 	if (smack[0] != '-') {
 		skp = smk_import_entry(smack, 0);
-		if (skp == NULL) {
-			rc = -EINVAL;
+		if (IS_ERR(skp)) {
+			rc = PTR_ERR(skp);
 			goto free_out;
 		}
 	} else {
@@ -1619,8 +1602,8 @@ static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
 	}
 
 	skp = smk_import_entry(data, count);
-	if (skp == NULL) {
-		rc = -EINVAL;
+	if (IS_ERR(skp)) {
+		rc = PTR_ERR(skp);
 		goto out;
 	}
 
@@ -1643,34 +1626,79 @@ static const struct file_operations smk_ambient_ops = {
 	.llseek		= default_llseek,
 };
 
-/**
- * smk_read_onlycap - read() for smackfs/onlycap
- * @filp: file pointer, not actually used
- * @buf: where to put the result
- * @cn: maximum to send along
- * @ppos: where to start
- *
- * Returns number of bytes read or error code, as appropriate
+/*
+ * Seq_file operations for /smack/onlycap
  */
-static ssize_t smk_read_onlycap(struct file *filp, char __user *buf,
-				size_t cn, loff_t *ppos)
+static void *onlycap_seq_start(struct seq_file *s, loff_t *pos)
 {
-	char *smack = "";
-	ssize_t rc = -EINVAL;
-	int asize;
+	return smk_seq_start(s, pos, &smack_onlycap_list);
+}
 
-	if (*ppos != 0)
-		return 0;
+static void *onlycap_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	return smk_seq_next(s, v, pos, &smack_onlycap_list);
+}
 
-	if (smack_onlycap != NULL)
-		smack = smack_onlycap->smk_known;
+static int onlycap_seq_show(struct seq_file *s, void *v)
+{
+	struct list_head *list = v;
+	struct smack_onlycap *sop =
+		list_entry_rcu(list, struct smack_onlycap, list);
 
-	asize = strlen(smack) + 1;
+	seq_puts(s, sop->smk_label->smk_known);
+	seq_putc(s, ' ');
 
-	if (cn >= asize)
-		rc = simple_read_from_buffer(buf, cn, ppos, smack, asize);
+	return 0;
+}
 
-	return rc;
+static const struct seq_operations onlycap_seq_ops = {
+	.start = onlycap_seq_start,
+	.next  = onlycap_seq_next,
+	.show  = onlycap_seq_show,
+	.stop  = smk_seq_stop,
+};
+
+static int smk_open_onlycap(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &onlycap_seq_ops);
+}
+
+/**
+ * smk_list_swap_rcu - swap public list with a private one in RCU-safe way
+ * The caller must hold appropriate mutex to prevent concurrent modifications
+ * to the public list.
+ * Private list is assumed to be not accessible to other threads yet.
+ *
+ * @public: public list
+ * @private: private list
+ */
+static void smk_list_swap_rcu(struct list_head *public,
+			      struct list_head *private)
+{
+	struct list_head *first, *last;
+
+	if (list_empty(public)) {
+		list_splice_init_rcu(private, public, synchronize_rcu);
+	} else {
+		/* Remember public list before replacing it */
+		first = public->next;
+		last = public->prev;
+
+		/* Publish private list in place of public in RCU-safe way */
+		private->prev->next = public;
+		private->next->prev = public;
+		rcu_assign_pointer(public->next, private->next);
+		public->prev = private->prev;
+
+		synchronize_rcu();
+
+		/* When all readers are done with the old public list,
+		 * attach it in place of private */
+		private->next = first;
+		private->prev = last;
+		first->prev = private;
+		last->next = private;
+	}
 }
 
 /**
@@ -1686,47 +1714,79 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
 				 size_t count, loff_t *ppos)
 {
 	char *data;
-	struct smack_known *skp = smk_of_task(current->cred->security);
+	char *data_parse;
+	char *tok;
+	struct smack_known *skp;
+	struct smack_onlycap *sop;
+	struct smack_onlycap *sop2;
+	LIST_HEAD(list_tmp);
 	int rc = count;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
 		return -EPERM;
 
-	/*
-	 * This can be done using smk_access() but is done
-	 * explicitly for clarity. The smk_access() implementation
-	 * would use smk_access(smack_onlycap, MAY_WRITE)
-	 */
-	if (smack_onlycap != NULL && smack_onlycap != skp)
-		return -EPERM;
-
 	data = kzalloc(count + 1, GFP_KERNEL);
 	if (data == NULL)
 		return -ENOMEM;
 
+	if (copy_from_user(data, buf, count) != 0) {
+		kfree(data);
+		return -EFAULT;
+	}
+
+	data_parse = data;
+	while ((tok = strsep(&data_parse, " ")) != NULL) {
+		if (!*tok)
+			continue;
+
+		skp = smk_import_entry(tok, 0);
+		if (IS_ERR(skp)) {
+			rc = PTR_ERR(skp);
+			break;
+		}
+
+		sop = kzalloc(sizeof(*sop), GFP_KERNEL);
+		if (sop == NULL) {
+			rc = -ENOMEM;
+			break;
+		}
+
+		sop->smk_label = skp;
+		list_add_rcu(&sop->list, &list_tmp);
+	}
+	kfree(data);
+
 	/*
-	 * Should the null string be passed in unset the onlycap value.
-	 * This seems like something to be careful with as usually
-	 * smk_import only expects to return NULL for errors. It
-	 * is usually the case that a nullstring or "\n" would be
-	 * bad to pass to smk_import but in fact this is useful here.
+	 * Clear the smack_onlycap on invalid label errors. This means
+	 * that we can pass a null string to unset the onlycap value.
 	 *
-	 * smk_import will also reject a label beginning with '-',
+	 * Importing will also reject a label beginning with '-',
 	 * so "-usecapabilities" will also work.
+	 *
+	 * But do so only on invalid label, not on system errors.
+	 * The invalid label must be first to count as clearing attempt.
 	 */
-	if (copy_from_user(data, buf, count) != 0)
-		rc = -EFAULT;
-	else
-		smack_onlycap = smk_import_entry(data, count);
+	if (rc == -EINVAL && list_empty(&list_tmp))
+		rc = count;
+
+	if (rc >= 0) {
+		mutex_lock(&smack_onlycap_lock);
+		smk_list_swap_rcu(&smack_onlycap_list, &list_tmp);
+		mutex_unlock(&smack_onlycap_lock);
+	}
+
+	list_for_each_entry_safe(sop, sop2, &list_tmp, list)
+		kfree(sop);
 
-	kfree(data);
 	return rc;
 }
 
 static const struct file_operations smk_onlycap_ops = {
-	.read		= smk_read_onlycap,
+	.open		= smk_open_onlycap,
+	.read		= seq_read,
 	.write		= smk_write_onlycap,
-	.llseek		= default_llseek,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
 };
 
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
@@ -1773,6 +1833,7 @@ static ssize_t smk_write_unconfined(struct file *file, const char __user *buf,
 					size_t count, loff_t *ppos)
 {
 	char *data;
+	struct smack_known *skp;
 	int rc = count;
 
 	if (!smack_privileged(CAP_MAC_ADMIN))
@@ -1782,21 +1843,31 @@ static ssize_t smk_write_unconfined(struct file *file, const char __user *buf,
 	if (data == NULL)
 		return -ENOMEM;
 
+	if (copy_from_user(data, buf, count) != 0) {
+		rc = -EFAULT;
+		goto freeout;
+	}
+
 	/*
-	 * Should the null string be passed in unset the unconfined value.
-	 * This seems like something to be careful with as usually
-	 * smk_import only expects to return NULL for errors. It
-	 * is usually the case that a nullstring or "\n" would be
-	 * bad to pass to smk_import but in fact this is useful here.
+	 * Clear the smack_unconfined on invalid label errors. This means
+	 * that we can pass a null string to unset the unconfined value.
 	 *
-	 * smk_import will also reject a label beginning with '-',
+	 * Importing will also reject a label beginning with '-',
 	 * so "-confine" will also work.
+	 *
+	 * But do so only on invalid label, not on system errors.
 	 */
-	if (copy_from_user(data, buf, count) != 0)
-		rc = -EFAULT;
-	else
-		smack_unconfined = smk_import_entry(data, count);
+	skp = smk_import_entry(data, count);
+	if (PTR_ERR(skp) == -EINVAL)
+		skp = NULL;
+	else if (IS_ERR(skp)) {
+		rc = PTR_ERR(skp);
+		goto freeout;
+	}
+
+	smack_unconfined = skp;
 
+freeout:
 	kfree(data);
 	return rc;
 }
@@ -1895,7 +1966,7 @@ static int load_self_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
 	struct smack_rule *srp =
-		 list_entry(list, struct smack_rule, list);
+		list_entry_rcu(list, struct smack_rule, list);
 
 	smk_rule_show(s, srp, SMK_LABELLEN);
 
@@ -1980,7 +2051,7 @@ static ssize_t smk_user_access(struct file *file, const char __user *buf,
 		res = smk_access(rule.smk_subject, rule.smk_object,
 				 rule.smk_access1, NULL);
 	else if (res != -ENOENT)
-		return -EINVAL;
+		return res;
 
 	/*
 	 * smk_access() can return a value > 0 in the "bringup" case.
@@ -2024,7 +2095,7 @@ static int load2_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
 	struct smack_master_list *smlp =
-		 list_entry(list, struct smack_master_list, list);
+		list_entry_rcu(list, struct smack_master_list, list);
 
 	smk_rule_show(s, smlp->smk_rule, SMK_LONGLABEL);
 
@@ -2101,7 +2172,7 @@ static int load_self2_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
 	struct smack_rule *srp =
-		 list_entry(list, struct smack_rule, list);
+		list_entry_rcu(list, struct smack_rule, list);
 
 	smk_rule_show(s, srp, SMK_LONGLABEL);
 
@@ -2209,8 +2280,8 @@ static ssize_t smk_write_revoke_subj(struct file *file, const char __user *buf,
 	}
 
 	cp = smk_parse_smack(data, count);
-	if (cp == NULL) {
-		rc = -EINVAL;
+	if (IS_ERR(cp)) {
+		rc = PTR_ERR(cp);
 		goto free_out;
 	}
 
@@ -2341,10 +2412,10 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
 		rc = -EFAULT;
 	else {
 		skp = smk_import_entry(data, count);
-		if (skp == NULL)
-			rc = -EINVAL;
+		if (IS_ERR(skp))
+			rc = PTR_ERR(skp);
 		else
-			smack_syslog_label = smk_import_entry(data, count);
+			smack_syslog_label = skp;
 	}
 
 	kfree(data);