Smack: IPv6 host labeling

IPv6 appears to be (finally) coming of age with the
influx of autonomous devices. In support of this, add
the ability to associate a Smack label with IPv6 addresses.

This patch also cleans up some of the conditional
compilation associated with the introduction of
secmark processing. It's now more obvious which bit
of code goes with which feature.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

1 files changed, 352 insertions, 76 deletions

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 81a2888a9908..11b752b366ea 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -29,6 +29,7 @@
 #include <linux/magic.h>
 #include "smack.h"
 
+#define BEBITS	(sizeof(__be32) * 8)
 /*
  * smackfs pseudo filesystem.
  */
@@ -40,7 +41,7 @@ enum smk_inos {
 	SMK_DOI		= 5,	/* CIPSO DOI */
 	SMK_DIRECT	= 6,	/* CIPSO level indicating direct label */
 	SMK_AMBIENT	= 7,	/* internet ambient label */
-	SMK_NETLBLADDR	= 8,	/* single label hosts */
+	SMK_NET4ADDR	= 8,	/* single label hosts */
 	SMK_ONLYCAP	= 9,	/* the only "capable" label */
 	SMK_LOGGING	= 10,	/* logging */
 	SMK_LOAD_SELF	= 11,	/* task specific rules */
@@ -57,6 +58,9 @@ enum smk_inos {
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 	SMK_UNCONFINED	= 22,	/* define an unconfined label */
 #endif
+#if IS_ENABLED(CONFIG_IPV6)
+	SMK_NET6ADDR	= 23,	/* single label IPv6 hosts */
+#endif /* CONFIG_IPV6 */
 };
 
 /*
@@ -64,7 +68,10 @@ enum smk_inos {
  */
 static DEFINE_MUTEX(smack_cipso_lock);
 static DEFINE_MUTEX(smack_ambient_lock);
-static DEFINE_MUTEX(smk_netlbladdr_lock);
+static DEFINE_MUTEX(smk_net4addr_lock);
+#if IS_ENABLED(CONFIG_IPV6)
+static DEFINE_MUTEX(smk_net6addr_lock);
+#endif /* CONFIG_IPV6 */
 
 /*
  * This is the "ambient" label for network traffic.
@@ -118,7 +125,10 @@ int smack_ptrace_rule = SMACK_PTRACE_DEFAULT;
  * can write to the specified label.
  */
 
-LIST_HEAD(smk_netlbladdr_list);
+LIST_HEAD(smk_net4addr_list);
+#if IS_ENABLED(CONFIG_IPV6)
+LIST_HEAD(smk_net6addr_list);
+#endif /* CONFIG_IPV6 */
 
 /*
  * Rule lists are maintained for each label.
@@ -140,11 +150,6 @@ struct smack_parsed_rule {
 
 static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT;
 
-struct smack_known smack_cipso_option = {
-	.smk_known	= SMACK_CIPSO_OPTION,
-	.smk_secid	= 0,
-};
-
 /*
  * Values for parsing cipso rules
  * SMK_DIGITLEN: Length of a digit field in a rule.
@@ -1047,92 +1052,90 @@ static const struct file_operations smk_cipso2_ops = {
  * Seq_file read operations for /smack/netlabel
  */
 
-static void *netlbladdr_seq_start(struct seq_file *s, loff_t *pos)
+static void *net4addr_seq_start(struct seq_file *s, loff_t *pos)
 {
-	return smk_seq_start(s, pos, &smk_netlbladdr_list);
+	return smk_seq_start(s, pos, &smk_net4addr_list);
 }
 
-static void *netlbladdr_seq_next(struct seq_file *s, void *v, loff_t *pos)
+static void *net4addr_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
-	return smk_seq_next(s, v, pos, &smk_netlbladdr_list);
+	return smk_seq_next(s, v, pos, &smk_net4addr_list);
 }
-#define BEBITS	(sizeof(__be32) * 8)
 
 /*
  * Print host/label pairs
  */
-static int netlbladdr_seq_show(struct seq_file *s, void *v)
+static int net4addr_seq_show(struct seq_file *s, void *v)
 {
 	struct list_head *list = v;
-	struct smk_netlbladdr *skp =
-			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);
-
-	for (maskn = 0; temp_mask; temp_mask <<= 1, maskn++);
+	struct smk_net4addr *skp =
+			list_entry_rcu(list, struct smk_net4addr, list);
+	char *kp = SMACK_CIPSO_OPTION;
 
-	seq_printf(s, "%u.%u.%u.%u/%d %s\n",
-		hp[0], hp[1], hp[2], hp[3], maskn, skp->smk_label->smk_known);
+	if (skp->smk_label != NULL)
+		kp = skp->smk_label->smk_known;
+	seq_printf(s, "%pI4/%d %s\n", &skp->smk_host.s_addr,
+			skp->smk_masks, kp);
 
 	return 0;
 }
 
-static const struct seq_operations netlbladdr_seq_ops = {
-	.start = netlbladdr_seq_start,
-	.next  = netlbladdr_seq_next,
-	.show  = netlbladdr_seq_show,
+static const struct seq_operations net4addr_seq_ops = {
+	.start = net4addr_seq_start,
+	.next  = net4addr_seq_next,
+	.show  = net4addr_seq_show,
 	.stop  = smk_seq_stop,
 };
 
 /**
- * smk_open_netlbladdr - open() for /smack/netlabel
+ * smk_open_net4addr - open() for /smack/netlabel
  * @inode: inode structure representing file
  * @file: "netlabel" file pointer
  *
- * Connect our netlbladdr_seq_* operations with /smack/netlabel
+ * Connect our net4addr_seq_* operations with /smack/netlabel
  * file_operations
  */
-static int smk_open_netlbladdr(struct inode *inode, struct file *file)
+static int smk_open_net4addr(struct inode *inode, struct file *file)
 {
-	return seq_open(file, &netlbladdr_seq_ops);
+	return seq_open(file, &net4addr_seq_ops);
 }
 
 /**
- * smk_netlbladdr_insert
+ * smk_net4addr_insert
  * @new : netlabel to insert
  *
- * This helper insert netlabel in the smack_netlbladdrs list
+ * This helper insert netlabel in the smack_net4addrs list
  * sorted by netmask length (longest to smallest)
- * locked by &smk_netlbladdr_lock in smk_write_netlbladdr
+ * locked by &smk_net4addr_lock in smk_write_net4addr
  *
  */
-static void smk_netlbladdr_insert(struct smk_netlbladdr *new)
+static void smk_net4addr_insert(struct smk_net4addr *new)
 {
-	struct smk_netlbladdr *m, *m_next;
+	struct smk_net4addr *m;
+	struct smk_net4addr *m_next;
 
-	if (list_empty(&smk_netlbladdr_list)) {
-		list_add_rcu(&new->list, &smk_netlbladdr_list);
+	if (list_empty(&smk_net4addr_list)) {
+		list_add_rcu(&new->list, &smk_net4addr_list);
 		return;
 	}
 
-	m = list_entry_rcu(smk_netlbladdr_list.next,
-			   struct smk_netlbladdr, list);
+	m = list_entry_rcu(smk_net4addr_list.next,
+			   struct smk_net4addr, list);
 
 	/* the comparison '>' is a bit hacky, but works */
-	if (new->smk_mask.s_addr > m->smk_mask.s_addr) {
-		list_add_rcu(&new->list, &smk_netlbladdr_list);
+	if (new->smk_masks > m->smk_masks) {
+		list_add_rcu(&new->list, &smk_net4addr_list);
 		return;
 	}
 
-	list_for_each_entry_rcu(m, &smk_netlbladdr_list, list) {
-		if (list_is_last(&m->list, &smk_netlbladdr_list)) {
+	list_for_each_entry_rcu(m, &smk_net4addr_list, list) {
+		if (list_is_last(&m->list, &smk_net4addr_list)) {
 			list_add_rcu(&new->list, &m->list);
 			return;
 		}
 		m_next = list_entry_rcu(m->list.next,
-					struct smk_netlbladdr, list);
-		if (new->smk_mask.s_addr > m_next->smk_mask.s_addr) {
+					struct smk_net4addr, list);
+		if (new->smk_masks > m_next->smk_masks) {
 			list_add_rcu(&new->list, &m->list);
 			return;
 		}
@@ -1141,28 +1144,29 @@ static void smk_netlbladdr_insert(struct smk_netlbladdr *new)
 
 
 /**
- * smk_write_netlbladdr - write() for /smack/netlabel
+ * smk_write_net4addr - write() for /smack/netlabel
  * @file: file pointer, not actually used
  * @buf: where to get the data from
  * @count: bytes sent
  * @ppos: where to start
  *
- * Accepts only one netlbladdr per write call.
+ * Accepts only one net4addr per write call.
  * Returns number of bytes written or error code, as appropriate
  */
-static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
+static ssize_t smk_write_net4addr(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
-	struct smk_netlbladdr *snp;
+	struct smk_net4addr *snp;
 	struct sockaddr_in newname;
 	char *smack;
-	struct smack_known *skp;
+	struct smack_known *skp = NULL;
 	char *data;
 	char *host = (char *)&newname.sin_addr.s_addr;
 	int rc;
 	struct netlbl_audit audit_info;
 	struct in_addr mask;
 	unsigned int m;
+	unsigned int masks;
 	int found;
 	u32 mask_bits = (1<<31);
 	__be32 nsa;
@@ -1200,7 +1204,7 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 	data[count] = '\0';
 
 	rc = sscanf(data, "%hhd.%hhd.%hhd.%hhd/%u %s",
-		&host[0], &host[1], &host[2], &host[3], &m, smack);
+		&host[0], &host[1], &host[2], &host[3], &masks, smack);
 	if (rc != 6) {
 		rc = sscanf(data, "%hhd.%hhd.%hhd.%hhd %s",
 			&host[0], &host[1], &host[2], &host[3], smack);
@@ -1209,8 +1213,9 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 			goto free_out;
 		}
 		m = BEBITS;
+		masks = 32;
 	}
-	if (m > BEBITS) {
+	if (masks > BEBITS) {
 		rc = -EINVAL;
 		goto free_out;
 	}
@@ -1225,16 +1230,16 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 			goto free_out;
 		}
 	} else {
-		/* check known options */
-		if (strcmp(smack, smack_cipso_option.smk_known) == 0)
-			skp = &smack_cipso_option;
-		else {
+		/*
+		 * Only the -CIPSO option is supported for IPv4
+		 */
+		if (strcmp(smack, SMACK_CIPSO_OPTION) != 0) {
 			rc = -EINVAL;
 			goto free_out;
 		}
 	}
 
-	for (temp_mask = 0; m > 0; m--) {
+	for (m = masks, temp_mask = 0; m > 0; m--) {
 		temp_mask |= mask_bits;
 		mask_bits >>= 1;
 	}
@@ -1245,14 +1250,13 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 	 * Only allow one writer at a time. Writes should be
 	 * quite rare and small in any case.
 	 */
-	mutex_lock(&smk_netlbladdr_lock);
+	mutex_lock(&smk_net4addr_lock);
 
 	nsa = newname.sin_addr.s_addr;
 	/* try to find if the prefix is already in the list */
 	found = 0;
-	list_for_each_entry_rcu(snp, &smk_netlbladdr_list, list) {
-		if (snp->smk_host.sin_addr.s_addr == nsa &&
-		    snp->smk_mask.s_addr == mask.s_addr) {
+	list_for_each_entry_rcu(snp, &smk_net4addr_list, list) {
+		if (snp->smk_host.s_addr == nsa && snp->smk_masks == masks) {
 			found = 1;
 			break;
 		}
@@ -1265,17 +1269,20 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 			rc = -ENOMEM;
 		else {
 			rc = 0;
-			snp->smk_host.sin_addr.s_addr = newname.sin_addr.s_addr;
+			snp->smk_host.s_addr = newname.sin_addr.s_addr;
 			snp->smk_mask.s_addr = mask.s_addr;
 			snp->smk_label = skp;
-			smk_netlbladdr_insert(snp);
+			snp->smk_masks = masks;
+			smk_net4addr_insert(snp);
 		}
 	} else {
-		/* we delete the unlabeled entry, only if the previous label
-		 * wasn't the special CIPSO option */
-		if (snp->smk_label != &smack_cipso_option)
+		/*
+		 * Delete the unlabeled entry, only if the previous label
+		 * wasn't the special CIPSO option
+		 */
+		if (snp->smk_label != NULL)
 			rc = netlbl_cfg_unlbl_static_del(&init_net, NULL,
-					&snp->smk_host.sin_addr, &snp->smk_mask,
+					&snp->smk_host, &snp->smk_mask,
 					PF_INET, &audit_info);
 		else
 			rc = 0;
@@ -1287,15 +1294,279 @@ static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
 	 * this host so that incoming packets get labeled.
 	 * but only if we didn't get the special CIPSO option
 	 */
-	if (rc == 0 && skp != &smack_cipso_option)
+	if (rc == 0 && skp != NULL)
 		rc = netlbl_cfg_unlbl_static_add(&init_net, NULL,
-			&snp->smk_host.sin_addr, &snp->smk_mask, PF_INET,
+			&snp->smk_host, &snp->smk_mask, PF_INET,
 			snp->smk_label->smk_secid, &audit_info);
 
 	if (rc == 0)
 		rc = count;
 
-	mutex_unlock(&smk_netlbladdr_lock);
+	mutex_unlock(&smk_net4addr_lock);
+
+free_out:
+	kfree(smack);
+free_data_out:
+	kfree(data);
+
+	return rc;
+}
+
+static const struct file_operations smk_net4addr_ops = {
+	.open           = smk_open_net4addr,
+	.read		= seq_read,
+	.llseek         = seq_lseek,
+	.write		= smk_write_net4addr,
+	.release        = seq_release,
+};
+
+#if IS_ENABLED(CONFIG_IPV6)
+/*
+ * Seq_file read operations for /smack/netlabel6
+ */
+
+static void *net6addr_seq_start(struct seq_file *s, loff_t *pos)
+{
+	return smk_seq_start(s, pos, &smk_net6addr_list);
+}
+
+static void *net6addr_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	return smk_seq_next(s, v, pos, &smk_net6addr_list);
+}
+
+/*
+ * Print host/label pairs
+ */
+static int net6addr_seq_show(struct seq_file *s, void *v)
+{
+	struct list_head *list = v;
+	struct smk_net6addr *skp =
+			 list_entry(list, struct smk_net6addr, list);
+
+	if (skp->smk_label != NULL)
+		seq_printf(s, "%pI6/%d %s\n", &skp->smk_host, skp->smk_masks,
+				skp->smk_label->smk_known);
+
+	return 0;
+}
+
+static const struct seq_operations net6addr_seq_ops = {
+	.start = net6addr_seq_start,
+	.next  = net6addr_seq_next,
+	.show  = net6addr_seq_show,
+	.stop  = smk_seq_stop,
+};
+
+/**
+ * smk_open_net6addr - open() for /smack/netlabel
+ * @inode: inode structure representing file
+ * @file: "netlabel" file pointer
+ *
+ * Connect our net6addr_seq_* operations with /smack/netlabel
+ * file_operations
+ */
+static int smk_open_net6addr(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &net6addr_seq_ops);
+}
+
+/**
+ * smk_net6addr_insert
+ * @new : entry to insert
+ *
+ * This inserts an entry in the smack_net6addrs list
+ * sorted by netmask length (longest to smallest)
+ * locked by &smk_net6addr_lock in smk_write_net6addr
+ *
+ */
+static void smk_net6addr_insert(struct smk_net6addr *new)
+{
+	struct smk_net6addr *m_next;
+	struct smk_net6addr *m;
+
+	if (list_empty(&smk_net6addr_list)) {
+		list_add_rcu(&new->list, &smk_net6addr_list);
+		return;
+	}
+
+	m = list_entry_rcu(smk_net6addr_list.next,
+			   struct smk_net6addr, list);
+
+	if (new->smk_masks > m->smk_masks) {
+		list_add_rcu(&new->list, &smk_net6addr_list);
+		return;
+	}
+
+	list_for_each_entry_rcu(m, &smk_net6addr_list, list) {
+		if (list_is_last(&m->list, &smk_net6addr_list)) {
+			list_add_rcu(&new->list, &m->list);
+			return;
+		}
+		m_next = list_entry_rcu(m->list.next,
+					struct smk_net6addr, list);
+		if (new->smk_masks > m_next->smk_masks) {
+			list_add_rcu(&new->list, &m->list);
+			return;
+		}
+	}
+}
+
+
+/**
+ * smk_write_net6addr - write() for /smack/netlabel
+ * @file: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Accepts only one net6addr per write call.
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_net6addr(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	struct smk_net6addr *snp;
+	struct in6_addr newname;
+	struct in6_addr fullmask;
+	struct smack_known *skp = NULL;
+	char *smack;
+	char *data;
+	int rc = 0;
+	int found = 0;
+	int i;
+	unsigned int scanned[8];
+	unsigned int m;
+	unsigned int mask = 128;
+
+	/*
+	 * Must have privilege.
+	 * No partial writes.
+	 * Enough data must be present.
+	 * "<addr/mask, as a:b:c:d:e:f:g:h/e><space><label>"
+	 * "<addr, as a:b:c:d:e:f:g:h><space><label>"
+	 */
+	if (!smack_privileged(CAP_MAC_ADMIN))
+		return -EPERM;
+	if (*ppos != 0)
+		return -EINVAL;
+	if (count < SMK_NETLBLADDRMIN)
+		return -EINVAL;
+
+	data = kzalloc(count + 1, GFP_KERNEL);
+	if (data == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(data, buf, count) != 0) {
+		rc = -EFAULT;
+		goto free_data_out;
+	}
+
+	smack = kzalloc(count + 1, GFP_KERNEL);
+	if (smack == NULL) {
+		rc = -ENOMEM;
+		goto free_data_out;
+	}
+
+	data[count] = '\0';
+
+	i = sscanf(data, "%x:%x:%x:%x:%x:%x:%x:%x/%u %s",
+			&scanned[0], &scanned[1], &scanned[2], &scanned[3],
+			&scanned[4], &scanned[5], &scanned[6], &scanned[7],
+			&mask, smack);
+	if (i != 10) {
+		i = sscanf(data, "%x:%x:%x:%x:%x:%x:%x:%x %s",
+				&scanned[0], &scanned[1], &scanned[2],
+				&scanned[3], &scanned[4], &scanned[5],
+				&scanned[6], &scanned[7], smack);
+		if (i != 9) {
+			rc = -EINVAL;
+			goto free_out;
+		}
+	}
+	if (mask > 128) {
+		rc = -EINVAL;
+		goto free_out;
+	}
+	for (i = 0; i < 8; i++) {
+		if (scanned[i] > 0xffff) {
+			rc = -EINVAL;
+			goto free_out;
+		}
+		newname.s6_addr16[i] = htons(scanned[i]);
+	}
+
+	/*
+	 * If smack begins with '-', it is an option, don't import it
+	 */
+	if (smack[0] != '-') {
+		skp = smk_import_entry(smack, 0);
+		if (skp == NULL) {
+			rc = -EINVAL;
+			goto free_out;
+		}
+	} else {
+		/*
+		 * Only -DELETE is supported for IPv6
+		 */
+		if (strcmp(smack, SMACK_DELETE_OPTION) != 0) {
+			rc = -EINVAL;
+			goto free_out;
+		}
+	}
+
+	for (i = 0, m = mask; i < 8; i++) {
+		if (m >= 16) {
+			fullmask.s6_addr16[i] = 0xffff;
+			m -= 16;
+		} else if (m > 0) {
+			fullmask.s6_addr16[i] = (1 << m) - 1;
+			m = 0;
+		} else
+			fullmask.s6_addr16[i] = 0;
+		newname.s6_addr16[i] &= fullmask.s6_addr16[i];
+	}
+
+	/*
+	 * Only allow one writer at a time. Writes should be
+	 * quite rare and small in any case.
+	 */
+	mutex_lock(&smk_net6addr_lock);
+	/*
+	 * Try to find the prefix in the list
+	 */
+	list_for_each_entry_rcu(snp, &smk_net6addr_list, list) {
+		if (mask != snp->smk_masks)
+			continue;
+		for (found = 1, i = 0; i < 8; i++) {
+			if (newname.s6_addr16[i] !=
+			    snp->smk_host.s6_addr16[i]) {
+				found = 0;
+				break;
+			}
+		}
+		if (found == 1)
+			break;
+	}
+	if (found == 0) {
+		snp = kzalloc(sizeof(*snp), GFP_KERNEL);
+		if (snp == NULL)
+			rc = -ENOMEM;
+		else {
+			snp->smk_host = newname;
+			snp->smk_mask = fullmask;
+			snp->smk_masks = mask;
+			snp->smk_label = skp;
+			smk_net6addr_insert(snp);
+		}
+	} else {
+		snp->smk_label = skp;
+	}
+
+	if (rc == 0)
+		rc = count;
+
+	mutex_unlock(&smk_net6addr_lock);
 
 free_out:
 	kfree(smack);
@@ -1305,13 +1576,14 @@ free_data_out:
 	return rc;
 }
 
-static const struct file_operations smk_netlbladdr_ops = {
-	.open           = smk_open_netlbladdr,
+static const struct file_operations smk_net6addr_ops = {
+	.open           = smk_open_net6addr,
 	.read		= seq_read,
 	.llseek         = seq_lseek,
-	.write		= smk_write_netlbladdr,
+	.write		= smk_write_net6addr,
 	.release        = seq_release,
 };
+#endif /* CONFIG_IPV6 */
 
 /**
  * smk_read_doi - read() for /smack/doi
@@ -2515,8 +2787,8 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent)
 			"direct", &smk_direct_ops, S_IRUGO|S_IWUSR},
 		[SMK_AMBIENT] = {
 			"ambient", &smk_ambient_ops, S_IRUGO|S_IWUSR},
-		[SMK_NETLBLADDR] = {
-			"netlabel", &smk_netlbladdr_ops, S_IRUGO|S_IWUSR},
+		[SMK_NET4ADDR] = {
+			"netlabel", &smk_net4addr_ops, S_IRUGO|S_IWUSR},
 		[SMK_ONLYCAP] = {
 			"onlycap", &smk_onlycap_ops, S_IRUGO|S_IWUSR},
 		[SMK_LOGGING] = {
@@ -2548,6 +2820,10 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent)
 		[SMK_UNCONFINED] = {
 			"unconfined", &smk_unconfined_ops, S_IRUGO|S_IWUSR},
 #endif
+#if IS_ENABLED(CONFIG_IPV6)
+		[SMK_NET6ADDR] = {
+			"ipv6host", &smk_net6addr_ops, S_IRUGO|S_IWUSR},
+#endif /* CONFIG_IPV6 */
 		/* last one */
 			{""}
 	};