Smack: Simplified Mandatory Access Control Kernel

Smack is the Simplified Mandatory Access Control Kernel.

Smack implements mandatory access control (MAC) using labels
attached to tasks and data containers, including files, SVIPC,
and other tasks. Smack is a kernel based scheme that requires
an absolute minimum of application support and a very small
amount of configuration data.

Smack uses extended attributes and
provides a set of general mount options, borrowing technics used
elsewhere. Smack uses netlabel for CIPSO labeling. Smack provides
a pseudo-filesystem smackfs that is used for manipulation of
system Smack attributes.

The patch, patches for ls and sshd, a README, a startup script,
and x86 binaries for ls and sshd are also available on

    http://www.schaufler-ca.com

Development has been done using Fedora Core 7 in a virtual machine
environment and on an old Sony laptop.

Smack provides mandatory access controls based on the label attached
to a task and the label attached to the object it is attempting to
access. Smack labels are deliberately short (1-23 characters) text
strings. Single character labels using special characters are reserved
for system use. The only operation applied to Smack labels is equality
comparison. No wildcards or expressions, regular or otherwise, are
used. Smack labels are composed of printable characters and may not
include "/".

A file always gets the Smack label of the task that created it.

Smack defines and uses these labels:

    "*" - pronounced "star"
    "_" - pronounced "floor"
    "^" - pronounced "hat"
    "?" - pronounced "huh"

The access rules enforced by Smack are, in order:

1. Any access requested by a task labeled "*" is denied.
2. A read or execute access requested by a task labeled "^"
   is permitted.
3. A read or execute access requested on an object labeled "_"
   is permitted.
4. Any access requested on an object labeled "*" is permitted.
5. Any access requested by a task on an object with the same
   label is permitted.
6. Any access requested that is explicitly defined in the loaded
   rule set is permitted.
7. Any other access is denied.

Rules may be explicitly defined by writing subject,object,access
triples to /smack/load.

Smack rule sets can be easily defined that describe Bell&LaPadula
sensitivity, Biba integrity, and a variety of interesting
configurations. Smack rule sets can be modified on the fly to
accommodate changes in the operating environment or even the time
of day.

Some practical use cases:

Hierarchical levels. The less common of the two usual uses
for MLS systems is to define hierarchical levels, often
unclassified, confidential, secret, and so on. To set up smack
to support this, these rules could be defined:

   C        Unclass rx
   S        C       rx
   S        Unclass rx
   TS       S       rx
   TS       C       rx
   TS       Unclass rx

A TS process can read S, C, and Unclass data, but cannot write it.
An S process can read C and Unclass. Note that specifying that
TS can read S and S can read C does not imply TS can read C, it
has to be explicitly stated.

Non-hierarchical categories. This is the more common of the
usual uses for an MLS system. Since the default rule is that a
subject cannot access an object with a different label no
access rules are required to implement compartmentalization.

A case that the Bell & LaPadula policy does not allow is demonstrated
with this Smack access rule:

A case that Bell&LaPadula does not allow that Smack does:

    ESPN    ABC   r
    ABC     ESPN  r

On my portable video device I have two applications, one that
shows ABC programming and the other ESPN programming. ESPN wants
to show me sport stories that show up as news, and ABC will
only provide minimal information about a sports story if ESPN
is covering it. Each side can look at the other's info, neither
can change the other. Neither can see what FOX is up to, which
is just as well all things considered.

Another case that I especially like:

    SatData Guard   w
    Guard   Publish w

A program running with the Guard label opens a UDP socket and
accepts messages sent by a program running with a SatData label.
The Guard program inspects the message to ensure it is wholesome
and if it is sends it to a program running with the Publish label.
This program then puts the information passed in an appropriate
place. Note that the Guard program cannot write to a Publish
file system object because file system semanitic require read as
well as write.

The four cases (categories, levels, mutual read, guardbox) here
are all quite real, and problems I've been asked to solve over
the years. The first two are easy to do with traditonal MLS systems
while the last two you can't without invoking privilege, at least
for a while.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: Joshua Brindle <method@manicmethod.com>
Cc: Paul Moore <paul.moore@hp.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Cc: "Ahmed S. Darwish" <darwish.07@gmail.com>
Cc: Andrew G. Morgan <morgan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 981 insertions, 0 deletions

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
new file mode 100644
index 00000000000..15aa37f65b3
--- /dev/null
+++ b/security/smack/smackfs.c
@@ -0,0 +1,981 @@
+/*
+ * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *  	it under the terms of the GNU General Public License as published by
+ *	the Free Software Foundation, version 2.
+ *
+ * Authors:
+ * 	Casey Schaufler <casey@schaufler-ca.com>
+ * 	Ahmed S. Darwish <darwish.07@gmail.com>
+ *
+ * Special thanks to the authors of selinuxfs.
+ *
+ *	Karl MacMillan <kmacmillan@tresys.com>
+ *	James Morris <jmorris@redhat.com>
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/vmalloc.h>
+#include <linux/security.h>
+#include <linux/mutex.h>
+#include <net/netlabel.h>
+#include <net/cipso_ipv4.h>
+#include <linux/seq_file.h>
+#include <linux/ctype.h>
+#include "smack.h"
+
+/*
+ * smackfs pseudo filesystem.
+ */
+
+enum smk_inos {
+	SMK_ROOT_INO	= 2,
+	SMK_LOAD	= 3,	/* load policy */
+	SMK_CIPSO	= 4,	/* load label -> CIPSO mapping */
+	SMK_DOI		= 5,	/* CIPSO DOI */
+	SMK_DIRECT	= 6,	/* CIPSO level indicating direct label */
+	SMK_AMBIENT	= 7,	/* internet ambient label */
+	SMK_NLTYPE	= 8,	/* label scheme to use by default */
+};
+
+/*
+ * List locks
+ */
+static DEFINE_MUTEX(smack_list_lock);
+static DEFINE_MUTEX(smack_cipso_lock);
+
+/*
+ * This is the "ambient" label for network traffic.
+ * If it isn't somehow marked, use this.
+ * It can be reset via smackfs/ambient
+ */
+char *smack_net_ambient = smack_known_floor.smk_known;
+
+/*
+ * This is the default packet marking scheme for network traffic.
+ * It can be reset via smackfs/nltype
+ */
+int smack_net_nltype = NETLBL_NLTYPE_CIPSOV4;
+
+/*
+ * This is the level in a CIPSO header that indicates a
+ * smack label is contained directly in the category set.
+ * It can be reset via smackfs/direct
+ */
+int smack_cipso_direct = SMACK_CIPSO_DIRECT_DEFAULT;
+
+static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT;
+struct smk_list_entry *smack_list;
+
+#define	SEQ_READ_FINISHED	1
+
+/*
+ * Disable concurrent writing open() operations
+ */
+static struct semaphore smack_write_sem;
+
+/*
+ * Values for parsing cipso rules
+ * SMK_DIGITLEN: Length of a digit field in a rule.
+ * SMK_CIPSOMEN: Minimum possible cipso rule length.
+ */
+#define SMK_DIGITLEN 4
+#define SMK_CIPSOMIN (SMK_MAXLEN + 2 * SMK_DIGITLEN)
+
+/*
+ * Seq_file read operations for /smack/load
+ */
+
+static void *load_seq_start(struct seq_file *s, loff_t *pos)
+{
+	if (*pos == SEQ_READ_FINISHED)
+		return NULL;
+
+	return smack_list;
+}
+
+static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct smk_list_entry *skp = ((struct smk_list_entry *) v)->smk_next;
+
+	if (skp == NULL)
+		*pos = SEQ_READ_FINISHED;
+
+	return skp;
+}
+
+static int load_seq_show(struct seq_file *s, void *v)
+{
+	struct smk_list_entry *slp = (struct smk_list_entry *) v;
+	struct smack_rule *srp = &slp->smk_rule;
+
+	seq_printf(s, "%s %s", (char *)srp->smk_subject,
+		   (char *)srp->smk_object);
+
+	seq_putc(s, ' ');
+
+	if (srp->smk_access & MAY_READ)
+		seq_putc(s, 'r');
+	if (srp->smk_access & MAY_WRITE)
+		seq_putc(s, 'w');
+	if (srp->smk_access & MAY_EXEC)
+		seq_putc(s, 'x');
+	if (srp->smk_access & MAY_APPEND)
+		seq_putc(s, 'a');
+	if (srp->smk_access == 0)
+		seq_putc(s, '-');
+
+	seq_putc(s, '\n');
+
+	return 0;
+}
+
+static void load_seq_stop(struct seq_file *s, void *v)
+{
+	/* No-op */
+}
+
+static struct seq_operations load_seq_ops = {
+	.start = load_seq_start,
+	.next  = load_seq_next,
+	.show  = load_seq_show,
+	.stop  = load_seq_stop,
+};
+
+/**
+ * smk_open_load - open() for /smack/load
+ * @inode: inode structure representing file
+ * @file: "load" file pointer
+ *
+ * For reading, use load_seq_* seq_file reading operations.
+ */
+static int smk_open_load(struct inode *inode, struct file *file)
+{
+	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
+		return seq_open(file, &load_seq_ops);
+
+	if (down_interruptible(&smack_write_sem))
+		return -ERESTARTSYS;
+
+	return 0;
+}
+
+/**
+ * smk_release_load - release() for /smack/load
+ * @inode: inode structure representing file
+ * @file: "load" file pointer
+ *
+ * For a reading session, use the seq_file release
+ * implementation.
+ * Otherwise, we are at the end of a writing session so
+ * clean everything up.
+ */
+static int smk_release_load(struct inode *inode, struct file *file)
+{
+	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
+		return seq_release(inode, file);
+
+	up(&smack_write_sem);
+	return 0;
+}
+
+/**
+ * smk_set_access - add a rule to the rule list
+ * @srp: the new rule to add
+ *
+ * Looks through the current subject/object/access list for
+ * the subject/object pair and replaces the access that was
+ * there. If the pair isn't found add it with the specified
+ * access.
+ */
+static void smk_set_access(struct smack_rule *srp)
+{
+	struct smk_list_entry *sp;
+	struct smk_list_entry *newp;
+
+	mutex_lock(&smack_list_lock);
+
+	for (sp = smack_list; sp != NULL; sp = sp->smk_next)
+		if (sp->smk_rule.smk_subject == srp->smk_subject &&
+		    sp->smk_rule.smk_object == srp->smk_object) {
+			sp->smk_rule.smk_access = srp->smk_access;
+			break;
+		}
+
+	if (sp == NULL) {
+		newp = kzalloc(sizeof(struct smk_list_entry), GFP_KERNEL);
+		newp->smk_rule = *srp;
+		newp->smk_next = smack_list;
+		smack_list = newp;
+	}
+
+	mutex_unlock(&smack_list_lock);
+
+	return;
+}
+
+/**
+ * smk_write_load - write() for /smack/load
+ * @filp: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start - must be 0
+ *
+ * Get one smack access rule from above.
+ * The format is exactly:
+ *     char subject[SMK_LABELLEN]
+ *     char object[SMK_LABELLEN]
+ *     char access[SMK_ACCESSKINDS]
+ *
+ *     Anything following is commentary and ignored.
+ *
+ * writes must be SMK_LABELLEN+SMK_LABELLEN+4 bytes.
+ */
+#define MINIMUM_LOAD (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSKINDS)
+
+static ssize_t smk_write_load(struct file *file, const char __user *buf,
+			      size_t count, loff_t *ppos)
+{
+	struct smack_rule rule;
+	char *data;
+	int rc = -EINVAL;
+
+	/*
+	 * Must have privilege.
+	 * No partial writes.
+	 * Enough data must be present.
+	 */
+	if (!capable(CAP_MAC_ADMIN))
+		return -EPERM;
+	if (*ppos != 0)
+		return -EINVAL;
+	if (count < MINIMUM_LOAD)
+		return -EINVAL;
+
+	data = kzalloc(count, GFP_KERNEL);
+	if (data == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(data, buf, count) != 0) {
+		rc = -EFAULT;
+		goto out;
+	}
+
+	rule.smk_subject = smk_import(data, 0);
+	if (rule.smk_subject == NULL)
+		goto out;
+
+	rule.smk_object = smk_import(data + SMK_LABELLEN, 0);
+	if (rule.smk_object == NULL)
+		goto out;
+
+	rule.smk_access = 0;
+
+	switch (data[SMK_LABELLEN + SMK_LABELLEN]) {
+	case '-':
+		break;
+	case 'r':
+	case 'R':
+		rule.smk_access |= MAY_READ;
+		break;
+	default:
+		goto out;
+	}
+
+	switch (data[SMK_LABELLEN + SMK_LABELLEN + 1]) {
+	case '-':
+		break;
+	case 'w':
+	case 'W':
+		rule.smk_access |= MAY_WRITE;
+		break;
+	default:
+		goto out;
+	}
+
+	switch (data[SMK_LABELLEN + SMK_LABELLEN + 2]) {
+	case '-':
+		break;
+	case 'x':
+	case 'X':
+		rule.smk_access |= MAY_EXEC;
+		break;
+	default:
+		goto out;
+	}
+
+	switch (data[SMK_LABELLEN + SMK_LABELLEN + 3]) {
+	case '-':
+		break;
+	case 'a':
+	case 'A':
+		rule.smk_access |= MAY_READ;
+		break;
+	default:
+		goto out;
+	}
+
+	smk_set_access(&rule);
+	rc = count;
+
+out:
+	kfree(data);
+	return rc;
+}
+
+static const struct file_operations smk_load_ops = {
+	.open           = smk_open_load,
+	.read		= seq_read,
+	.llseek         = seq_lseek,
+	.write		= smk_write_load,
+	.release        = smk_release_load,
+};
+
+/**
+ * smk_cipso_doi - initialize the CIPSO domain
+ */
+void smk_cipso_doi(void)
+{
+	int rc;
+	struct cipso_v4_doi *doip;
+	struct netlbl_audit audit_info;
+
+	rc = netlbl_cfg_map_del(NULL, &audit_info);
+	if (rc != 0)
+		printk(KERN_WARNING "%s:%d remove rc = %d\n",
+		       __func__, __LINE__, rc);
+
+	doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL);
+	if (doip == NULL)
+		panic("smack:  Failed to initialize cipso DOI.\n");
+	doip->map.std = NULL;
+	doip->doi = smk_cipso_doi_value;
+	doip->type = CIPSO_V4_MAP_PASS;
+	doip->tags[0] = CIPSO_V4_TAG_RBITMAP;
+	for (rc = 1; rc < CIPSO_V4_TAG_MAXCNT; rc++)
+		doip->tags[rc] = CIPSO_V4_TAG_INVALID;
+
+	rc = netlbl_cfg_cipsov4_add_map(doip, NULL, &audit_info);
+	if (rc != 0)
+		printk(KERN_WARNING "%s:%d add rc = %d\n",
+		       __func__, __LINE__, rc);
+}
+
+/*
+ * Seq_file read operations for /smack/cipso
+ */
+
+static void *cipso_seq_start(struct seq_file *s, loff_t *pos)
+{
+	if (*pos == SEQ_READ_FINISHED)
+		return NULL;
+
+	return smack_known;
+}
+
+static void *cipso_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct smack_known *skp = ((struct smack_known *) v)->smk_next;
+
+	/*
+	 * Omit labels with no associated cipso value
+	 */
+	while (skp != NULL && !skp->smk_cipso)
+		skp = skp->smk_next;
+
+	if (skp == NULL)
+		*pos = SEQ_READ_FINISHED;
+
+	return skp;
+}
+
+/*
+ * Print cipso labels in format:
+ * label level[/cat[,cat]]
+ */
+static int cipso_seq_show(struct seq_file *s, void *v)
+{
+	struct smack_known *skp = (struct smack_known *) v;
+	struct smack_cipso *scp = skp->smk_cipso;
+	char *cbp;
+	char sep = '/';
+	int cat = 1;
+	int i;
+	unsigned char m;
+
+	if (scp == NULL)
+		return 0;
+
+	seq_printf(s, "%s %3d", (char *)&skp->smk_known, scp->smk_level);
+
+	cbp = scp->smk_catset;
+	for (i = 0; i < SMK_LABELLEN; i++)
+		for (m = 0x80; m != 0; m >>= 1) {
+			if (m & cbp[i]) {
+				seq_printf(s, "%c%d", sep, cat);
+				sep = ',';
+			}
+			cat++;
+		}
+
+	seq_putc(s, '\n');
+
+	return 0;
+}
+
+static void cipso_seq_stop(struct seq_file *s, void *v)
+{
+	/* No-op */
+}
+
+static struct seq_operations cipso_seq_ops = {
+	.start = cipso_seq_start,
+	.stop  = cipso_seq_stop,
+	.next  = cipso_seq_next,
+	.show  = cipso_seq_show,
+};
+
+/**
+ * smk_open_cipso - open() for /smack/cipso
+ * @inode: inode structure representing file
+ * @file: "cipso" file pointer
+ *
+ * Connect our cipso_seq_* operations with /smack/cipso
+ * file_operations
+ */
+static int smk_open_cipso(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &cipso_seq_ops);
+}
+
+/**
+ * smk_write_cipso - write() for /smack/cipso
+ * @filp: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Accepts only one cipso rule per write call.
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_cipso(struct file *file, const char __user *buf,
+			       size_t count, loff_t *ppos)
+{
+	struct smack_known *skp;
+	struct smack_cipso *scp = NULL;
+	char mapcatset[SMK_LABELLEN];
+	int maplevel;
+	int cat;
+	int catlen;
+	ssize_t rc = -EINVAL;
+	char *data = NULL;
+	char *rule;
+	int ret;
+	int i;
+
+	/*
+	 * Must have privilege.
+	 * No partial writes.
+	 * Enough data must be present.
+	 */
+	if (!capable(CAP_MAC_ADMIN))
+		return -EPERM;
+	if (*ppos != 0)
+		return -EINVAL;
+	if (count <= SMK_CIPSOMIN)
+		return -EINVAL;
+
+	data = kzalloc(count + 1, GFP_KERNEL);
+	if (data == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(data, buf, count) != 0) {
+		rc = -EFAULT;
+		goto unlockedout;
+	}
+
+	data[count] = '\0';
+	rule = data;
+	/*
+	 * Only allow one writer at a time. Writes should be
+	 * quite rare and small in any case.
+	 */
+	mutex_lock(&smack_cipso_lock);
+
+	skp = smk_import_entry(rule, 0);
+	if (skp == NULL)
+		goto out;
+
+	rule += SMK_LABELLEN;;
+	ret = sscanf(rule, "%d", &maplevel);
+	if (ret != 1 || maplevel > SMACK_CIPSO_MAXLEVEL)
+		goto out;
+
+	rule += SMK_DIGITLEN;
+	ret = sscanf(rule, "%d", &catlen);
+	if (ret != 1 || catlen > SMACK_CIPSO_MAXCATNUM)
+		goto out;
+
+	if (count <= (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
+		goto out;
+
+	memset(mapcatset, 0, sizeof(mapcatset));
+
+	for (i = 0; i < catlen; i++) {
+		rule += SMK_DIGITLEN;
+		ret = sscanf(rule, "%d", &cat);
+		if (ret != 1 || cat > SMACK_CIPSO_MAXCATVAL)
+			goto out;
+
+		smack_catset_bit(cat, mapcatset);
+	}
+
+	if (skp->smk_cipso == NULL) {
+		scp = kzalloc(sizeof(struct smack_cipso), GFP_KERNEL);
+		if (scp == NULL) {
+			rc = -ENOMEM;
+			goto out;
+		}
+	}
+
+	spin_lock_bh(&skp->smk_cipsolock);
+
+	if (scp == NULL)
+		scp = skp->smk_cipso;
+	else
+		skp->smk_cipso = scp;
+
+	scp->smk_level = maplevel;
+	memcpy(scp->smk_catset, mapcatset, sizeof(mapcatset));
+
+	spin_unlock_bh(&skp->smk_cipsolock);
+
+	rc = count;
+out:
+	mutex_unlock(&smack_cipso_lock);
+unlockedout:
+	kfree(data);
+	return rc;
+}
+
+static const struct file_operations smk_cipso_ops = {
+	.open           = smk_open_cipso,
+	.read		= seq_read,
+	.llseek         = seq_lseek,
+	.write		= smk_write_cipso,
+	.release        = seq_release,
+};
+
+/**
+ * smk_read_doi - read() for /smack/doi
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @count: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t smk_read_doi(struct file *filp, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	char temp[80];
+	ssize_t rc;
+
+	if (*ppos != 0)
+		return 0;
+
+	sprintf(temp, "%d", smk_cipso_doi_value);
+	rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+
+	return rc;
+}
+
+/**
+ * smk_write_doi - write() for /smack/doi
+ * @filp: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_doi(struct file *file, const char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	char temp[80];
+	int i;
+
+	if (!capable(CAP_MAC_ADMIN))
+		return -EPERM;
+
+	if (count >= sizeof(temp) || count == 0)
+		return -EINVAL;
+
+	if (copy_from_user(temp, buf, count) != 0)
+		return -EFAULT;
+
+	temp[count] = '\0';
+
+	if (sscanf(temp, "%d", &i) != 1)
+		return -EINVAL;
+
+	smk_cipso_doi_value = i;
+
+	smk_cipso_doi();
+
+	return count;
+}
+
+static const struct file_operations smk_doi_ops = {
+	.read		= smk_read_doi,
+	.write		= smk_write_doi,
+};
+
+/**
+ * smk_read_direct - read() for /smack/direct
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @count: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t smk_read_direct(struct file *filp, char __user *buf,
+			       size_t count, loff_t *ppos)
+{
+	char temp[80];
+	ssize_t rc;
+
+	if (*ppos != 0)
+		return 0;
+
+	sprintf(temp, "%d", smack_cipso_direct);
+	rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+
+	return rc;
+}
+
+/**
+ * smk_write_direct - write() for /smack/direct
+ * @filp: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_direct(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	char temp[80];
+	int i;
+
+	if (!capable(CAP_MAC_ADMIN))
+		return -EPERM;
+
+	if (count >= sizeof(temp) || count == 0)
+		return -EINVAL;
+
+	if (copy_from_user(temp, buf, count) != 0)
+		return -EFAULT;
+
+	temp[count] = '\0';
+
+	if (sscanf(temp, "%d", &i) != 1)
+		return -EINVAL;
+
+	smack_cipso_direct = i;
+
+	return count;
+}
+
+static const struct file_operations smk_direct_ops = {
+	.read		= smk_read_direct,
+	.write		= smk_write_direct,
+};
+
+/**
+ * smk_read_ambient - read() for /smack/ambient
+ * @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
+ */
+static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
+				size_t cn, loff_t *ppos)
+{
+	ssize_t rc;
+	char out[SMK_LABELLEN];
+	int asize;
+
+	if (*ppos != 0)
+		return 0;
+	/*
+	 * Being careful to avoid a problem in the case where
+	 * smack_net_ambient gets changed in midstream.
+	 * Since smack_net_ambient is always set with a value
+	 * from the label list, including initially, and those
+	 * never get freed, the worst case is that the pointer
+	 * gets changed just after this strncpy, in which case
+	 * the value passed up is incorrect. Locking around
+	 * smack_net_ambient wouldn't be any better than this
+	 * copy scheme as by the time the caller got to look
+	 * at the ambient value it would have cleared the lock
+	 * and been changed.
+	 */
+	strncpy(out, smack_net_ambient, SMK_LABELLEN);
+	asize = strlen(out) + 1;
+
+	if (cn < asize)
+		return -EINVAL;
+
+	rc = simple_read_from_buffer(buf, cn, ppos, out, asize);
+
+	return rc;
+}
+
+/**
+ * smk_write_ambient - write() for /smack/ambient
+ * @filp: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	char in[SMK_LABELLEN];
+	char *smack;
+
+	if (!capable(CAP_MAC_ADMIN))
+		return -EPERM;
+
+	if (count >= SMK_LABELLEN)
+		return -EINVAL;
+
+	if (copy_from_user(in, buf, count) != 0)
+		return -EFAULT;
+
+	smack = smk_import(in, count);
+	if (smack == NULL)
+		return -EINVAL;
+
+	smack_net_ambient = smack;
+
+	return count;
+}
+
+static const struct file_operations smk_ambient_ops = {
+	.read		= smk_read_ambient,
+	.write		= smk_write_ambient,
+};
+
+struct option_names {
+	int	o_number;
+	char	*o_name;
+	char	*o_alias;
+};
+
+static struct option_names netlbl_choices[] = {
+	{ NETLBL_NLTYPE_RIPSO,
+		NETLBL_NLTYPE_RIPSO_NAME,	"ripso" },
+	{ NETLBL_NLTYPE_CIPSOV4,
+		NETLBL_NLTYPE_CIPSOV4_NAME,	"cipsov4" },
+	{ NETLBL_NLTYPE_CIPSOV4,
+		NETLBL_NLTYPE_CIPSOV4_NAME,	"cipso" },
+	{ NETLBL_NLTYPE_CIPSOV6,
+		NETLBL_NLTYPE_CIPSOV6_NAME,	"cipsov6" },
+	{ NETLBL_NLTYPE_UNLABELED,
+		NETLBL_NLTYPE_UNLABELED_NAME,	"unlabeled" },
+};
+
+/**
+ * smk_read_nltype - read() for /smack/nltype
+ * @filp: file pointer, not actually used
+ * @buf: where to put the result
+ * @count: maximum to send along
+ * @ppos: where to start
+ *
+ * Returns number of bytes read or error code, as appropriate
+ */
+static ssize_t smk_read_nltype(struct file *filp, char __user *buf,
+			       size_t count, loff_t *ppos)
+{
+	char bound[40];
+	ssize_t rc;
+	int i;
+
+	if (count < SMK_LABELLEN)
+		return -EINVAL;
+
+	if (*ppos != 0)
+		return 0;
+
+	sprintf(bound, "unknown");
+
+	for (i = 0; i < ARRAY_SIZE(netlbl_choices); i++)
+		if (smack_net_nltype == netlbl_choices[i].o_number) {
+			sprintf(bound, "%s", netlbl_choices[i].o_name);
+			break;
+		}
+
+	rc = simple_read_from_buffer(buf, count, ppos, bound, strlen(bound));
+
+	return rc;
+}
+
+/**
+ * smk_write_nltype - write() for /smack/nltype
+ * @filp: file pointer, not actually used
+ * @buf: where to get the data from
+ * @count: bytes sent
+ * @ppos: where to start
+ *
+ * Returns number of bytes written or error code, as appropriate
+ */
+static ssize_t smk_write_nltype(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	char bound[40];
+	char *cp;
+	int i;
+
+	if (!capable(CAP_MAC_ADMIN))
+		return -EPERM;
+
+	if (count >= 40)
+		return -EINVAL;
+
+	if (copy_from_user(bound, buf, count) != 0)
+		return -EFAULT;
+
+	bound[count] = '\0';
+	cp = strchr(bound, ' ');
+	if (cp != NULL)
+		*cp = '\0';
+	cp = strchr(bound, '\n');
+	if (cp != NULL)
+		*cp = '\0';
+
+	for (i = 0; i < ARRAY_SIZE(netlbl_choices); i++)
+		if (strcmp(bound, netlbl_choices[i].o_name) == 0 ||
+		    strcmp(bound, netlbl_choices[i].o_alias) == 0) {
+			smack_net_nltype = netlbl_choices[i].o_number;
+			return count;
+		}
+	/*
+	 * Not a valid choice.
+	 */
+	return -EINVAL;
+}
+
+static const struct file_operations smk_nltype_ops = {
+	.read		= smk_read_nltype,
+	.write		= smk_write_nltype,
+};
+
+/**
+ * smk_fill_super - fill the /smackfs superblock
+ * @sb: the empty superblock
+ * @data: unused
+ * @silent: unused
+ *
+ * Fill in the well known entries for /smack
+ *
+ * Returns 0 on success, an error code on failure
+ */
+static int smk_fill_super(struct super_block *sb, void *data, int silent)
+{
+	int rc;
+	struct inode *root_inode;
+
+	static struct tree_descr smack_files[] = {
+		[SMK_LOAD]	=
+			{"load", &smk_load_ops, S_IRUGO|S_IWUSR},
+		[SMK_CIPSO]	=
+			{"cipso", &smk_cipso_ops, S_IRUGO|S_IWUSR},
+		[SMK_DOI]	=
+			{"doi", &smk_doi_ops, S_IRUGO|S_IWUSR},
+		[SMK_DIRECT]	=
+			{"direct", &smk_direct_ops, S_IRUGO|S_IWUSR},
+		[SMK_AMBIENT]	=
+			{"ambient", &smk_ambient_ops, S_IRUGO|S_IWUSR},
+		[SMK_NLTYPE]	=
+			{"nltype", &smk_nltype_ops, S_IRUGO|S_IWUSR},
+		/* last one */ {""}
+	};
+
+	rc = simple_fill_super(sb, SMACK_MAGIC, smack_files);
+	if (rc != 0) {
+		printk(KERN_ERR "%s failed %d while creating inodes\n",
+			__func__, rc);
+		return rc;
+	}
+
+	root_inode = sb->s_root->d_inode;
+	root_inode->i_security = new_inode_smack(smack_known_floor.smk_known);
+
+	return 0;
+}
+
+/**
+ * smk_get_sb - get the smackfs superblock
+ * @fs_type: passed along without comment
+ * @flags: passed along without comment
+ * @dev_name: passed along without comment
+ * @data: passed along without comment
+ * @mnt: passed along without comment
+ *
+ * Just passes everything along.
+ *
+ * Returns what the lower level code does.
+ */
+static int smk_get_sb(struct file_system_type *fs_type,
+		      int flags, const char *dev_name, void *data,
+		      struct vfsmount *mnt)
+{
+	return get_sb_single(fs_type, flags, data, smk_fill_super, mnt);
+}
+
+static struct file_system_type smk_fs_type = {
+	.name		= "smackfs",
+	.get_sb		= smk_get_sb,
+	.kill_sb	= kill_litter_super,
+};
+
+static struct vfsmount *smackfs_mount;
+
+/**
+ * init_smk_fs - get the smackfs superblock
+ *
+ * register the smackfs
+ *
+ * Returns 0 unless the registration fails.
+ */
+static int __init init_smk_fs(void)
+{
+	int err;
+
+	err = register_filesystem(&smk_fs_type);
+	if (!err) {
+		smackfs_mount = kern_mount(&smk_fs_type);
+		if (IS_ERR(smackfs_mount)) {
+			printk(KERN_ERR "smackfs:  could not mount!\n");
+			err = PTR_ERR(smackfs_mount);
+			smackfs_mount = NULL;
+		}
+	}
+
+	sema_init(&smack_write_sem, 1);
+	smk_cipso_doi();
+
+	return err;
+}
+
+__initcall(init_smk_fs);