rcu: Make rcu_assign_pointer() unconditionally insert a memory barrier

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.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 <linux/slab.h>
#include <net/net_namespace.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_NETLBLADDR  = 8,    /* single label hosts */
        SMK_ONLYCAP     = 9,    /* the only "capable" label */
        SMK_LOGGING     = 10,   /* logging */
        SMK_LOAD_SELF   = 11,   /* task specific rules */
};

/*
 * List locks
 */
static DEFINE_MUTEX(smack_list_lock);
static DEFINE_MUTEX(smack_cipso_lock);
static DEFINE_MUTEX(smack_ambient_lock);
static DEFINE_MUTEX(smk_netlbladdr_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 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;

/*
 * 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.
 */
char *smack_onlycap;

/*
 * Certain IP addresses may be designated as single label hosts.
 * Packets are sent there unlabeled, but only from tasks that
 * can write to the specified label.
 */

LIST_HEAD(smk_netlbladdr_list);
LIST_HEAD(smack_rule_list);

static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT;

const char *smack_cipso_option = SMACK_CIPSO_OPTION;


#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_OACCESS     "rwxa"
#define SMK_ACCESS      "rwxat"
#define SMK_OACCESSLEN  (sizeof(SMK_OACCESS) - 1)
#define SMK_ACCESSLEN   (sizeof(SMK_ACCESS) - 1)
#define SMK_OLOADLEN    (SMK_LABELLEN + SMK_LABELLEN + SMK_OACCESSLEN)
#define SMK_LOADLEN     (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSLEN)

/**
 * smk_netlabel_audit_set - fill a netlbl_audit struct
 * @nap: structure to fill
 */
static void smk_netlabel_audit_set(struct netlbl_audit *nap)
{
        nap->loginuid = audit_get_loginuid(current);
        nap->sessionid = audit_get_sessionid(current);
        nap->secid = smack_to_secid(smk_of_current());
}

/*
 * Values for parsing single label host rules
 * "1.2.3.4 X"
 * "192.168.138.129/32 abcdefghijklmnopqrstuvw"
 */
#define SMK_NETLBLADDRMIN       9
#define SMK_NETLBLADDRMAX       42

/**
 * smk_set_access - add a rule to the rule list
 * @srp: the new rule to add
 * @rule_list: the list of rules
 * @rule_lock: the rule list lock
 *
 * 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.
 *
 * Returns 1 if a rule was found to exist already, 0 if it is new
 * Returns 0 if nothing goes wrong or -ENOMEM if it fails
 * during the allocation of the new pair to add.
 */
static int smk_set_access(struct smack_rule *srp, struct list_head *rule_list,
                                struct mutex *rule_lock)
{
        struct smack_rule *sp;
        int found = 0;

        mutex_lock(rule_lock);

        list_for_each_entry_rcu(sp, rule_list, list) {
                if (sp->smk_subject == srp->smk_subject &&
                    sp->smk_object == srp->smk_object) {
                        found = 1;
                        sp->smk_access = srp->smk_access;
                        break;
                }
        }
        if (found == 0)
                list_add_rcu(&srp->list, rule_list);

        mutex_unlock(rule_lock);

        return found;
}

/**
 * smk_write_load_list - write() for any /smack/load
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 * @rule_list: the list of rules to write to
 * @rule_lock: lock for the rule list
 *
 * 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_list(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos,
                                struct list_head *rule_list,
                                struct mutex *rule_lock)
{
        struct smack_rule *rule;
        char *data;
        int rc = -EINVAL;

        /*
         * No partial writes.
         * Enough data must be present.
         */
        if (*ppos != 0)
                return -EINVAL;
        /*
         * Minor hack for backward compatibility
         */
        if (count < (SMK_OLOADLEN) || count > SMK_LOADLEN)
                return -EINVAL;

        data = kzalloc(SMK_LOADLEN, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto out;
        }

        /*
         * More on the minor hack for backward compatibility
         */
        if (count == (SMK_OLOADLEN))
                data[SMK_OLOADLEN] = '-';

        rule = kzalloc(sizeof(*rule), GFP_KERNEL);
        if (rule == NULL) {
                rc = -ENOMEM;
                goto out;
        }

        rule->smk_subject = smk_import(data, 0);
        if (rule->smk_subject == NULL)
                goto out_free_rule;

        rule->smk_object = smk_import(data + SMK_LABELLEN, 0);
        if (rule->smk_object == NULL)
                goto out_free_rule;

        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_free_rule;
        }

        switch (data[SMK_LABELLEN + SMK_LABELLEN + 1]) {
        case '-':
                break;
        case 'w':
        case 'W':
                rule->smk_access |= MAY_WRITE;
                break;
        default:
                goto out_free_rule;
        }

        switch (data[SMK_LABELLEN + SMK_LABELLEN + 2]) {
        case '-':
                break;
        case 'x':
        case 'X':
                rule->smk_access |= MAY_EXEC;
                break;
        default:
                goto out_free_rule;
        }

        switch (data[SMK_LABELLEN + SMK_LABELLEN + 3]) {
        case '-':
                break;
        case 'a':
        case 'A':
                rule->smk_access |= MAY_APPEND;
                break;
        default:
                goto out_free_rule;
        }

        switch (data[SMK_LABELLEN + SMK_LABELLEN + 4]) {
        case '-':
                break;
        case 't':
        case 'T':
                rule->smk_access |= MAY_TRANSMUTE;
                break;
        default:
                goto out_free_rule;
        }

        rc = count;
        /*
         * smk_set_access returns true if there was already a rule
         * for the subject/object pair, and false if it was new.
         */
        if (!smk_set_access(rule, rule_list, rule_lock))
                goto out;

out_free_rule:
        kfree(rule);
out:
        kfree(data);
        return rc;
}


/*
 * 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;
        if (list_empty(&smack_rule_list))
                return NULL;
        return smack_rule_list.next;
}

static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct list_head *list = v;

        if (list_is_last(list, &smack_rule_list)) {
                *pos = SEQ_READ_FINISHED;
                return NULL;
        }
        return list->next;
}

static int load_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smack_rule *srp =
                 list_entry(list, struct smack_rule, list);

        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 & MAY_TRANSMUTE)
                seq_putc(s, 't');
        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 const 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_write_load - write() for /smack/load
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 *
 */
static ssize_t smk_write_load(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{

        /*
         * Must have privilege.
         * No partial writes.
         * Enough data must be present.
         */
        if (!capable(CAP_MAC_ADMIN))
                return -EPERM;

        return smk_write_load_list(file, buf, count, ppos, &smack_rule_list,
                                        &smack_list_lock);
}

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 nai;

        smk_netlabel_audit_set(&nai);

        rc = netlbl_cfg_map_del(NULL, PF_INET, NULL, NULL, &nai);
        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(doip, &nai);
        if (rc != 0) {
                printk(KERN_WARNING "%s:%d cipso add rc = %d\n",
                       __func__, __LINE__, rc);
                kfree(doip);
                return;
        }
        rc = netlbl_cfg_cipsov4_map_add(doip->doi, NULL, NULL, NULL, &nai);
        if (rc != 0) {
                printk(KERN_WARNING "%s:%d map add rc = %d\n",
                       __func__, __LINE__, rc);
                kfree(doip);
                return;
        }
}

/**
 * smk_unlbl_ambient - initialize the unlabeled domain
 * @oldambient: previous domain string
 */
static void smk_unlbl_ambient(char *oldambient)
{
        int rc;
        struct netlbl_audit nai;

        smk_netlabel_audit_set(&nai);

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

        rc = netlbl_cfg_unlbl_map_add(smack_net_ambient, PF_INET,
                                      NULL, NULL, &nai);
        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;
        if (list_empty(&smack_known_list))
                return NULL;

        return smack_known_list.next;
}

static void *cipso_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct list_head  *list = v;

        /*
         * labels with no associated cipso value wont be printed
         * in cipso_seq_show
         */
        if (list_is_last(list, &smack_known_list)) {
                *pos = SEQ_READ_FINISHED;
                return NULL;
        }

        return list->next;
}

/*
 * Print cipso labels in format:
 * label level[/cat[,cat]]
 */
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);
        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 const 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
 * @file: 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;
        }

        /* labels cannot begin with a '-' */
        if (data[0] == '-') {
                rc = -EINVAL;
                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,
};

/*
 * Seq_file read operations for /smack/netlabel
 */

static void *netlbladdr_seq_start(struct seq_file *s, loff_t *pos)
{
        if (*pos == SEQ_READ_FINISHED)
                return NULL;
        if (list_empty(&smk_netlbladdr_list))
                return NULL;
        return smk_netlbladdr_list.next;
}

static void *netlbladdr_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct list_head *list = v;

        if (list_is_last(list, &smk_netlbladdr_list)) {
                *pos = SEQ_READ_FINISHED;
                return NULL;
        }

        return list->next;
}
#define BEBITS  (sizeof(__be32) * 8)

/*
 * Print host/label pairs
 */
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);
        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++);

        seq_printf(s, "%u.%u.%u.%u/%d %s\n",
                hp[0], hp[1], hp[2], hp[3], maskn, skp->smk_label);

        return 0;
}

static void netlbladdr_seq_stop(struct seq_file *s, void *v)
{
        /* No-op */
}

static const struct seq_operations netlbladdr_seq_ops = {
        .start = netlbladdr_seq_start,
        .stop  = netlbladdr_seq_stop,
        .next  = netlbladdr_seq_next,
        .show  = netlbladdr_seq_show,
};

/**
 * smk_open_netlbladdr - open() for /smack/netlabel
 * @inode: inode structure representing file
 * @file: "netlabel" file pointer
 *
 * Connect our netlbladdr_seq_* operations with /smack/netlabel
 * file_operations
 */
static int smk_open_netlbladdr(struct inode *inode, struct file *file)
{
        return seq_open(file, &netlbladdr_seq_ops);
}

/**
 * smk_netlbladdr_insert
 * @new : netlabel to insert
 *
 * This helper insert netlabel in the smack_netlbladdrs list
 * sorted by netmask length (longest to smallest)
 * locked by &smk_netlbladdr_lock in smk_write_netlbladdr
 *
 */
static void smk_netlbladdr_insert(struct smk_netlbladdr *new)
{
        struct smk_netlbladdr *m, *m_next;

        if (list_empty(&smk_netlbladdr_list)) {
                list_add_rcu(&new->list, &smk_netlbladdr_list);
                return;
        }

        m = list_entry_rcu(smk_netlbladdr_list.next,
                           struct smk_netlbladdr, 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);
                return;
        }

        list_for_each_entry_rcu(m, &smk_netlbladdr_list, list) {
                if (list_is_last(&m->list, &smk_netlbladdr_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) {
                        list_add_rcu(&new->list, &m->list);
                        return;
                }
        }
}


/**
 * smk_write_netlbladdr - 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.
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct smk_netlbladdr *skp;
        struct sockaddr_in newname;
        char smack[SMK_LABELLEN];
        char *sp;
        char data[SMK_NETLBLADDRMAX + 1];
        char *host = (char *)&newname.sin_addr.s_addr;
        int rc;
        struct netlbl_audit audit_info;
        struct in_addr mask;
        unsigned int m;
        int found;
        u32 mask_bits = (1<<31);
        __be32 nsa;
        u32 temp_mask;

        /*
         * Must have privilege.
         * No partial writes.
         * Enough data must be present.
         * "<addr/mask, as a.b.c.d/e><space><label>"
         * "<addr, as a.b.c.d><space><label>"
         */
        if (!capable(CAP_MAC_ADMIN))
                return -EPERM;
        if (*ppos != 0)
                return -EINVAL;
        if (count < SMK_NETLBLADDRMIN || count > SMK_NETLBLADDRMAX)
                return -EINVAL;
        if (copy_from_user(data, buf, count) != 0)
                return -EFAULT;

        data[count] = '\0';

        rc = sscanf(data, "%hhd.%hhd.%hhd.%hhd/%d %s",
                &host[0], &host[1], &host[2], &host[3], &m, smack);
        if (rc != 6) {
                rc = sscanf(data, "%hhd.%hhd.%hhd.%hhd %s",
                        &host[0], &host[1], &host[2], &host[3], smack);
                if (rc != 5)
                        return -EINVAL;
                m = BEBITS;
        }
        if (m > BEBITS)
                return -EINVAL;

        /* if smack begins with '-', its an option, don't import it */
        if (smack[0] != '-') {
                sp = smk_import(smack, 0);
                if (sp == NULL)
                        return -EINVAL;
        } else {
                /* check known options */
                if (strcmp(smack, smack_cipso_option) == 0)
                        sp = (char *)smack_cipso_option;
                else
                        return -EINVAL;
        }

        for (temp_mask = 0; m > 0; m--) {
                temp_mask |= mask_bits;
                mask_bits >>= 1;
        }
        mask.s_addr = cpu_to_be32(temp_mask);

        newname.sin_addr.s_addr &= mask.s_addr;
        /*
         * Only allow one writer at a time. Writes should be
         * quite rare and small in any case.
         */
        mutex_lock(&smk_netlbladdr_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(skp, &smk_netlbladdr_list, list) {
                if (skp->smk_host.sin_addr.s_addr == nsa &&
                    skp->smk_mask.s_addr == mask.s_addr) {
                        found = 1;
                        break;
                }
        }
        smk_netlabel_audit_set(&audit_info);

        if (found == 0) {
                skp = kzalloc(sizeof(*skp), GFP_KERNEL);
                if (skp == NULL)
                        rc = -ENOMEM;
                else {
                        rc = 0;
                        skp->smk_host.sin_addr.s_addr = newname.sin_addr.s_addr;
                        skp->smk_mask.s_addr = mask.s_addr;
                        skp->smk_label = sp;
                        smk_netlbladdr_insert(skp);
                }
        } else {
                /* we delete the unlabeled entry, only if the previous label
                 * wasn't the special CIPSO option */
                if (skp->smk_label != smack_cipso_option)
                        rc = netlbl_cfg_unlbl_static_del(&init_net, NULL,
                                        &skp->smk_host.sin_addr, &skp->smk_mask,
                                        PF_INET, &audit_info);
                else
                        rc = 0;
                skp->smk_label = sp;
        }

        /*
         * Now tell netlabel about the single label nature of
         * this host so that incoming packets get labeled.
         * but only if we didn't get the special CIPSO option
         */
        if (rc == 0 && sp != smack_cipso_option)
                rc = netlbl_cfg_unlbl_static_add(&init_net, NULL,
                        &skp->smk_host.sin_addr, &skp->smk_mask, PF_INET,
                        smack_to_secid(skp->smk_label), &audit_info);

        if (rc == 0)
                rc = count;

        mutex_unlock(&smk_netlbladdr_lock);

        return rc;
}

static const struct file_operations smk_netlbladdr_ops = {
        .open           = smk_open_netlbladdr,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_netlbladdr,
        .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
 * @file: 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,
        .llseek         = default_llseek,
};

/**
 * 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
 * @file: 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,
        .llseek         = default_llseek,
};

/**
 * 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
 * @file: 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,
        .llseek         = default_llseek,
};

/**
 * smk_read_onlycap - read() for /smack/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
 */
static ssize_t smk_read_onlycap(struct file *filp, char __user *buf,
                                size_t cn, loff_t *ppos)
{
        char *smack = "";
        ssize_t rc = -EINVAL;
        int asize;

        if (*ppos != 0)
                return 0;

        if (smack_onlycap != NULL)
                smack = smack_onlycap;

        asize = strlen(smack) + 1;

        if (cn >= asize)
                rc = simple_read_from_buffer(buf, cn, ppos, smack, asize);

        return rc;
}

/**
 * smk_write_onlycap - write() for /smack/onlycap
 * @file: 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_onlycap(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        char in[SMK_LABELLEN];
        char *sp = smk_of_task(current->cred->security);

        if (!capable(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 != sp)
                return -EPERM;

        if (count >= SMK_LABELLEN)
                return -EINVAL;

        if (copy_from_user(in, buf, count) != 0)
                return -EFAULT;

        /*
         * 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.
         */
        smack_onlycap = smk_import(in, count);

        return count;
}

static const struct file_operations smk_onlycap_ops = {
        .read           = smk_read_onlycap,
        .write          = smk_write_onlycap,
        .llseek         = default_llseek,
};

/**
 * smk_read_logging - read() for /smack/logging
 * @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_logging(struct file *filp, char __user *buf,
                                size_t count, loff_t *ppos)
{
        char temp[32];
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        sprintf(temp, "%d\n", log_policy);
        rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
        return rc;
}

/**
 * smk_write_logging - write() for /smack/logging
 * @file: 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_logging(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        char temp[32];
        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;
        if (i < 0 || i > 3)
                return -EINVAL;
        log_policy = i;
        return count;
}



static const struct file_operations smk_logging_ops = {
        .read           = smk_read_logging,
        .write          = smk_write_logging,
        .llseek         = default_llseek,
};

/*
 * Seq_file read operations for /smack/load-self
 */

static void *load_self_seq_start(struct seq_file *s, loff_t *pos)
{
        struct task_smack *tsp = current_security();

        if (*pos == SEQ_READ_FINISHED)
                return NULL;
        if (list_empty(&tsp->smk_rules))
                return NULL;
        return tsp->smk_rules.next;
}

static void *load_self_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct task_smack *tsp = current_security();
        struct list_head *list = v;

        if (list_is_last(list, &tsp->smk_rules)) {
                *pos = SEQ_READ_FINISHED;
                return NULL;
        }
        return list->next;
}

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);

        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 & MAY_TRANSMUTE)
                seq_putc(s, 't');
        if (srp->smk_access == 0)
                seq_putc(s, '-');

        seq_putc(s, '\n');

        return 0;
}

static void load_self_seq_stop(struct seq_file *s, void *v)
{
        /* No-op */
}

static const struct seq_operations load_self_seq_ops = {
        .start = load_self_seq_start,
        .next  = load_self_seq_next,
        .show  = load_self_seq_show,
        .stop  = load_self_seq_stop,
};


/**
 * smk_open_load_self - open() for /smack/load-self
 * @inode: inode structure representing file
 * @file: "load" file pointer
 *
 * For reading, use load_seq_* seq_file reading operations.
 */
static int smk_open_load_self(struct inode *inode, struct file *file)
{
        return seq_open(file, &load_self_seq_ops);
}

/**
 * smk_write_load_self - write() for /smack/load-self
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 *
 */
static ssize_t smk_write_load_self(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        struct task_smack *tsp = current_security();

        return smk_write_load_list(file, buf, count, ppos, &tsp->smk_rules,
                                        &tsp->smk_rules_lock);
}

static const struct file_operations smk_load_self_ops = {
        .open           = smk_open_load_self,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_load_self,
        .release        = seq_release,
};
/**
 * 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_NETLBLADDR] = {
                        "netlabel", &smk_netlbladdr_ops, S_IRUGO|S_IWUSR},
                [SMK_ONLYCAP] = {
                        "onlycap", &smk_onlycap_ops, S_IRUGO|S_IWUSR},
                [SMK_LOGGING] = {
                        "logging", &smk_logging_ops, S_IRUGO|S_IWUSR},
                [SMK_LOAD_SELF] = {
                        "load-self", &smk_load_self_ops, S_IRUGO|S_IWUGO},
                /* 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_mount - 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
 *
 * Just passes everything along.
 *
 * Returns what the lower level code does.
 */
static struct dentry *smk_mount(struct file_system_type *fs_type,
                      int flags, const char *dev_name, void *data)
{
        return mount_single(fs_type, flags, data, smk_fill_super);
}

static struct file_system_type smk_fs_type = {
        .name           = "smackfs",
        .mount          = smk_mount,
        .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);