efirtc: push down the BKL

[linux-2.6/sactl.git] / security / smack / smackfs.c

/*
 * 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 <linux/audit.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);
static DEFINE_MUTEX(smack_ambient_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

/*
 * Values for parsing cipso rules
 * SMK_DIGITLEN: Length of a digit field in a rule.
 * SMK_CIPSOMIN: Minimum possible cipso rule length.
 * SMK_CIPSOMAX: Maximum possible cipso rule length.
 */
#define SMK_DIGITLEN 4
#define SMK_CIPSOMIN (SMK_LABELLEN + 2 * SMK_DIGITLEN)
#define SMK_CIPSOMAX (SMK_CIPSOMIN + SMACK_CIPSO_MAXCATNUM * SMK_DIGITLEN)

/*
 * Values for parsing MAC rules
 * SMK_ACCESS: Maximum possible combination of access permissions
 * SMK_ACCESSLEN: Maximum length for a rule access field
 * SMK_LOADLEN: Smack rule length
 */
#define SMK_ACCESS    "rwxa"
#define SMK_ACCESSLEN (sizeof(SMK_ACCESS) - 1)
#define SMK_LOADLEN   (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSLEN)


/*
 * 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)
{
        return seq_open(file, &load_seq_ops);
}

/**
 * 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_ACCESSLEN]
 *
 * writes must be SMK_LABELLEN+SMK_LABELLEN+SMK_ACCESSLEN bytes.
 */
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 != SMK_LOADLEN)
                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        = seq_release,
};

/**
 * smk_cipso_doi - initialize the CIPSO domain
 */
static void smk_cipso_doi(void)
{
        int rc;
        struct cipso_v4_doi *doip;
        struct netlbl_audit audit_info;

        audit_info.loginuid = audit_get_loginuid(current);
        audit_info.sessionid = audit_get_sessionid(current);
        audit_info.secid = smack_to_secid(current->security);

        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);
}

/**
 * smk_unlbl_ambient - initialize the unlabeled domain
 */
static void smk_unlbl_ambient(char *oldambient)
{
        int rc;
        struct netlbl_audit audit_info;

        audit_info.loginuid = audit_get_loginuid(current);
        audit_info.sessionid = audit_get_sessionid(current);
        audit_info.secid = smack_to_secid(current->security);

        if (oldambient != NULL) {
                rc = netlbl_cfg_map_del(oldambient, &audit_info);
                if (rc != 0)
                        printk(KERN_WARNING "%s:%d remove rc = %d\n",
                               __func__, __LINE__, rc);
        }

        rc = netlbl_cfg_unlbl_add_map(smack_net_ambient, &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 || count > SMK_CIPSOMAX)
                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;
        int asize;

        if (*ppos != 0)
                return 0;
        /*
         * Being careful to avoid a problem in the case where
         * smack_net_ambient gets changed in midstream.
         */
        mutex_lock(&smack_ambient_lock);

        asize = strlen(smack_net_ambient) + 1;

        if (cn >= asize)
                rc = simple_read_from_buffer(buf, cn, ppos,
                                             smack_net_ambient, asize);
        else
                rc = -EINVAL;

        mutex_unlock(&smack_ambient_lock);

        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 *oldambient;
        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;

        mutex_lock(&smack_ambient_lock);

        oldambient = smack_net_ambient;
        smack_net_ambient = smack;
        smk_unlbl_ambient(oldambient);

        mutex_unlock(&smack_ambient_lock);

        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
 *
 * Do not register smackfs if Smack wasn't enabled
 * on boot. We can not put this method normally under the
 * smack_init() code path since the security subsystem get
 * initialized before the vfs caches.
 *
 * Returns true if we were not chosen on boot or if
 * we were chosen and filesystem registration succeeded.
 */
static int __init init_smk_fs(void)
{
        int err;

        if (!security_module_enable(&smack_ops))
                return 0;

        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;
                }
        }

        smk_cipso_doi();
        smk_unlbl_ambient(NULL);

        return err;
}

__initcall(init_smk_fs);