selinuxfs.c

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/* Updated: Karl MacMillan <[email protected]>
 *
 *  Added conditional policy language extensions
 *
 *  Updated: Hewlett-Packard <[email protected]>
 *
 *  Added support for the policy capability bitmap
 *
 * Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
 * Copyright (C) 2003 - 2004 Tresys Technology, LLC
 * Copyright (C) 2004 Red Hat, Inc., James Morris <[email protected]>
 *  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.
 */

#include <linux/kernel.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/security.h>
#include <linux/major.h>
#include <linux/seq_file.h>
#include <linux/percpu.h>
#include <linux/audit.h>
#include <linux/uaccess.h>
#include <linux/kobject.h>
#include <linux/ctype.h>

/* selinuxfs pseudo filesystem for exporting the security policy API.
   Based on the proc code and the fs/nfsd/nfsctl.c code. */

#include "flask.h"
#include "avc.h"
#include "avc_ss.h"
#include "security.h"
#include "objsec.h"
#include "conditional.h"

/* Policy capability filenames */
static char *policycap_names[] = {
    "network_peer_controls",
    "open_perms"
};

unsigned int selinux_checkreqprot = CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE;

static int __init checkreqprot_setup(char *str)
{
    unsigned long checkreqprot;
    if (!strict_strtoul(str, 0, &checkreqprot))
        selinux_checkreqprot = checkreqprot ? 1 : 0;
    return 1;
}
__setup("checkreqprot=", checkreqprot_setup);

static DEFINE_MUTEX(sel_mutex);

/* global data for booleans */
static struct dentry *bool_dir;
static int bool_num;
static char **bool_pending_names;
static int *bool_pending_values;

/* global data for classes */
static struct dentry *class_dir;
static unsigned long last_class_ino;

static char policy_opened;

/* global data for policy capabilities */
static struct dentry *policycap_dir;

/* Check whether a task is allowed to use a security operation. */
static int task_has_security(struct task_struct *tsk,
                 u32 perms)
{
    const struct task_security_struct *tsec;
    u32 sid = 0;

    rcu_read_lock();
    tsec = __task_cred(tsk)->security;
    if (tsec)
        sid = tsec->sid;
    rcu_read_unlock();
    if (!tsec)
        return -EACCES;

    return avc_has_perm(sid, SECINITSID_SECURITY,
                SECCLASS_SECURITY, perms, NULL);
}

enum sel_inos {
    SEL_ROOT_INO = 2,
    SEL_LOAD,   /* load policy */
    SEL_ENFORCE,    /* get or set enforcing status */
    SEL_CONTEXT,    /* validate context */
    SEL_ACCESS, /* compute access decision */
    SEL_CREATE, /* compute create labeling decision */
    SEL_RELABEL,    /* compute relabeling decision */
    SEL_USER,   /* compute reachable user contexts */
    SEL_POLICYVERS, /* return policy version for this kernel */
    SEL_COMMIT_BOOLS, /* commit new boolean values */
    SEL_MLS,    /* return if MLS policy is enabled */
    SEL_DISABLE,    /* disable SELinux until next reboot */
    SEL_MEMBER, /* compute polyinstantiation membership decision */
    SEL_CHECKREQPROT, /* check requested protection, not kernel-applied one */
    SEL_COMPAT_NET, /* whether to use old compat network packet controls */
    SEL_REJECT_UNKNOWN, /* export unknown reject handling to userspace */
    SEL_DENY_UNKNOWN, /* export unknown deny handling to userspace */
    SEL_STATUS, /* export current status using mmap() */
    SEL_POLICY, /* allow userspace to read the in kernel policy */
    SEL_INO_NEXT,   /* The next inode number to use */
};

static unsigned long sel_last_ino = SEL_INO_NEXT - 1;

#define SEL_INITCON_INO_OFFSET      0x01000000
#define SEL_BOOL_INO_OFFSET     0x02000000
#define SEL_CLASS_INO_OFFSET        0x04000000
#define SEL_POLICYCAP_INO_OFFSET    0x08000000
#define SEL_INO_MASK            0x00ffffff

#define TMPBUFLEN   12
static ssize_t sel_read_enforce(struct file *filp, char __user *buf,
                size_t count, loff_t *ppos)
{
    char tmpbuf[TMPBUFLEN];
    ssize_t length;

    length = scnprintf(tmpbuf, TMPBUFLEN, "%d", selinux_enforcing);
    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

#ifdef CONFIG_SECURITY_SELINUX_DEVELOP
static ssize_t sel_write_enforce(struct file *file, const char __user *buf,
                 size_t count, loff_t *ppos)

{
    char *page = NULL;
    ssize_t length;
    int new_value;

    length = -ENOMEM;
    if (count >= PAGE_SIZE)
        goto out;

    /* No partial writes. */
    length = EINVAL;
    if (*ppos != 0)
        goto out;

    length = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    length = -EFAULT;
    if (copy_from_user(page, buf, count))
        goto out;

    length = -EINVAL;
    if (sscanf(page, "%d", &new_value) != 1)
        goto out;

    if (new_value != selinux_enforcing) {
        length = task_has_security(current, SECURITY__SETENFORCE);
        if (length)
            goto out;
        audit_log(current->audit_context, GFP_KERNEL, AUDIT_MAC_STATUS,
            "enforcing=%d old_enforcing=%d auid=%u ses=%u",
            new_value, selinux_enforcing,
            from_kuid(&init_user_ns, audit_get_loginuid(current)),
            audit_get_sessionid(current));
        selinux_enforcing = new_value;
        if (selinux_enforcing)
            avc_ss_reset(0);
        selnl_notify_setenforce(selinux_enforcing);
        selinux_status_update_setenforce(selinux_enforcing);
    }
    length = count;
out:
    free_page((unsigned long) page);
    return length;
}
#else
#define sel_write_enforce NULL
#endif

static const struct file_operations sel_enforce_ops = {
    .read       = sel_read_enforce,
    .write      = sel_write_enforce,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_read_handle_unknown(struct file *filp, char __user *buf,
                    size_t count, loff_t *ppos)
{
    char tmpbuf[TMPBUFLEN];
    ssize_t length;
    ino_t ino = filp->f_path.dentry->d_inode->i_ino;
    int handle_unknown = (ino == SEL_REJECT_UNKNOWN) ?
        security_get_reject_unknown() : !security_get_allow_unknown();

    length = scnprintf(tmpbuf, TMPBUFLEN, "%d", handle_unknown);
    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static const struct file_operations sel_handle_unknown_ops = {
    .read       = sel_read_handle_unknown,
    .llseek     = generic_file_llseek,
};

static int sel_open_handle_status(struct inode *inode, struct file *filp)
{
    struct page    *status = selinux_kernel_status_page();

    if (!status)
        return -ENOMEM;

    filp->private_data = status;

    return 0;
}

static ssize_t sel_read_handle_status(struct file *filp, char __user *buf,
                      size_t count, loff_t *ppos)
{
    struct page    *status = filp->private_data;

    BUG_ON(!status);

    return simple_read_from_buffer(buf, count, ppos,
                       page_address(status),
                       sizeof(struct selinux_kernel_status));
}

static int sel_mmap_handle_status(struct file *filp,
                  struct vm_area_struct *vma)
{
    struct page    *status = filp->private_data;
    unsigned long   size = vma->vm_end - vma->vm_start;

    BUG_ON(!status);

    /* only allows one page from the head */
    if (vma->vm_pgoff > 0 || size != PAGE_SIZE)
        return -EIO;
    /* disallow writable mapping */
    if (vma->vm_flags & VM_WRITE)
        return -EPERM;
    /* disallow mprotect() turns it into writable */
    vma->vm_flags &= ~VM_MAYWRITE;

    return remap_pfn_range(vma, vma->vm_start,
                   page_to_pfn(status),
                   size, vma->vm_page_prot);
}

static const struct file_operations sel_handle_status_ops = {
    .open       = sel_open_handle_status,
    .read       = sel_read_handle_status,
    .mmap       = sel_mmap_handle_status,
    .llseek     = generic_file_llseek,
};

#ifdef CONFIG_SECURITY_SELINUX_DISABLE
static ssize_t sel_write_disable(struct file *file, const char __user *buf,
                 size_t count, loff_t *ppos)

{
    char *page = NULL;
    ssize_t length;
    int new_value;

    length = -ENOMEM;
    if (count >= PAGE_SIZE)
        goto out;

    /* No partial writes. */
    length = -EINVAL;
    if (*ppos != 0)
        goto out;

    length = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    length = -EFAULT;
    if (copy_from_user(page, buf, count))
        goto out;

    length = -EINVAL;
    if (sscanf(page, "%d", &new_value) != 1)
        goto out;

    if (new_value) {
        length = selinux_disable();
        if (length)
            goto out;
        audit_log(current->audit_context, GFP_KERNEL, AUDIT_MAC_STATUS,
            "selinux=0 auid=%u ses=%u",
            from_kuid(&init_user_ns, audit_get_loginuid(current)),
            audit_get_sessionid(current));
    }

    length = count;
out:
    free_page((unsigned long) page);
    return length;
}
#else
#define sel_write_disable NULL
#endif

static const struct file_operations sel_disable_ops = {
    .write      = sel_write_disable,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_read_policyvers(struct file *filp, char __user *buf,
                   size_t count, loff_t *ppos)
{
    char tmpbuf[TMPBUFLEN];
    ssize_t length;

    length = scnprintf(tmpbuf, TMPBUFLEN, "%u", POLICYDB_VERSION_MAX);
    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static const struct file_operations sel_policyvers_ops = {
    .read       = sel_read_policyvers,
    .llseek     = generic_file_llseek,
};

/* declaration for sel_write_load */
static int sel_make_bools(void);
static int sel_make_classes(void);
static int sel_make_policycap(void);

/* declaration for sel_make_class_dirs */
static struct dentry *sel_make_dir(struct dentry *dir, const char *name,
            unsigned long *ino);

static ssize_t sel_read_mls(struct file *filp, char __user *buf,
                size_t count, loff_t *ppos)
{
    char tmpbuf[TMPBUFLEN];
    ssize_t length;

    length = scnprintf(tmpbuf, TMPBUFLEN, "%d",
               security_mls_enabled());
    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static const struct file_operations sel_mls_ops = {
    .read       = sel_read_mls,
    .llseek     = generic_file_llseek,
};

struct policy_load_memory {
    size_t len;
    void *data;
};

static int sel_open_policy(struct inode *inode, struct file *filp)
{
    struct policy_load_memory *plm = NULL;
    int rc;

    BUG_ON(filp->private_data);

    mutex_lock(&sel_mutex);

    rc = task_has_security(current, SECURITY__READ_POLICY);
    if (rc)
        goto err;

    rc = -EBUSY;
    if (policy_opened)
        goto err;

    rc = -ENOMEM;
    plm = kzalloc(sizeof(*plm), GFP_KERNEL);
    if (!plm)
        goto err;

    if (i_size_read(inode) != security_policydb_len()) {
        mutex_lock(&inode->i_mutex);
        i_size_write(inode, security_policydb_len());
        mutex_unlock(&inode->i_mutex);
    }

    rc = security_read_policy(&plm->data, &plm->len);
    if (rc)
        goto err;

    policy_opened = 1;

    filp->private_data = plm;

    mutex_unlock(&sel_mutex);

    return 0;
err:
    mutex_unlock(&sel_mutex);

    if (plm)
        vfree(plm->data);
    kfree(plm);
    return rc;
}

static int sel_release_policy(struct inode *inode, struct file *filp)
{
    struct policy_load_memory *plm = filp->private_data;

    BUG_ON(!plm);

    policy_opened = 0;

    vfree(plm->data);
    kfree(plm);

    return 0;
}

static ssize_t sel_read_policy(struct file *filp, char __user *buf,
                   size_t count, loff_t *ppos)
{
    struct policy_load_memory *plm = filp->private_data;
    int ret;

    mutex_lock(&sel_mutex);

    ret = task_has_security(current, SECURITY__READ_POLICY);
    if (ret)
        goto out;

    ret = simple_read_from_buffer(buf, count, ppos, plm->data, plm->len);
out:
    mutex_unlock(&sel_mutex);
    return ret;
}

static int sel_mmap_policy_fault(struct vm_area_struct *vma,
                 struct vm_fault *vmf)
{
    struct policy_load_memory *plm = vma->vm_file->private_data;
    unsigned long offset;
    struct page *page;

    if (vmf->flags & (FAULT_FLAG_MKWRITE | FAULT_FLAG_WRITE))
        return VM_FAULT_SIGBUS;

    offset = vmf->pgoff << PAGE_SHIFT;
    if (offset >= roundup(plm->len, PAGE_SIZE))
        return VM_FAULT_SIGBUS;

    page = vmalloc_to_page(plm->data + offset);
    get_page(page);

    vmf->page = page;

    return 0;
}

static struct vm_operations_struct sel_mmap_policy_ops = {
    .fault = sel_mmap_policy_fault,
    .page_mkwrite = sel_mmap_policy_fault,
};

static int sel_mmap_policy(struct file *filp, struct vm_area_struct *vma)
{
    if (vma->vm_flags & VM_SHARED) {
        /* do not allow mprotect to make mapping writable */
        vma->vm_flags &= ~VM_MAYWRITE;

        if (vma->vm_flags & VM_WRITE)
            return -EACCES;
    }

    vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
    vma->vm_ops = &sel_mmap_policy_ops;

    return 0;
}

static const struct file_operations sel_policy_ops = {
    .open       = sel_open_policy,
    .read       = sel_read_policy,
    .mmap       = sel_mmap_policy,
    .release    = sel_release_policy,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_write_load(struct file *file, const char __user *buf,
                  size_t count, loff_t *ppos)

{
    ssize_t length;
    void *data = NULL;

    mutex_lock(&sel_mutex);

    length = task_has_security(current, SECURITY__LOAD_POLICY);
    if (length)
        goto out;

    /* No partial writes. */
    length = -EINVAL;
    if (*ppos != 0)
        goto out;

    length = -EFBIG;
    if (count > 64 * 1024 * 1024)
        goto out;

    length = -ENOMEM;
    data = vmalloc(count);
    if (!data)
        goto out;

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

    length = security_load_policy(data, count);
    if (length)
        goto out;

    length = sel_make_bools();
    if (length)
        goto out1;

    length = sel_make_classes();
    if (length)
        goto out1;

    length = sel_make_policycap();
    if (length)
        goto out1;

    length = count;

out1:
    audit_log(current->audit_context, GFP_KERNEL, AUDIT_MAC_POLICY_LOAD,
        "policy loaded auid=%u ses=%u",
        from_kuid(&init_user_ns, audit_get_loginuid(current)),
        audit_get_sessionid(current));
out:
    mutex_unlock(&sel_mutex);
    vfree(data);
    return length;
}

static const struct file_operations sel_load_ops = {
    .write      = sel_write_load,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_write_context(struct file *file, char *buf, size_t size)
{
    char *canon = NULL;
    u32 sid, len;
    ssize_t length;

    length = task_has_security(current, SECURITY__CHECK_CONTEXT);
    if (length)
        goto out;

    length = security_context_to_sid(buf, size, &sid);
    if (length)
        goto out;

    length = security_sid_to_context(sid, &canon, &len);
    if (length)
        goto out;

    length = -ERANGE;
    if (len > SIMPLE_TRANSACTION_LIMIT) {
        printk(KERN_ERR "SELinux: %s:  context size (%u) exceeds "
            "payload max\n", __func__, len);
        goto out;
    }

    memcpy(buf, canon, len);
    length = len;
out:
    kfree(canon);
    return length;
}

static ssize_t sel_read_checkreqprot(struct file *filp, char __user *buf,
                     size_t count, loff_t *ppos)
{
    char tmpbuf[TMPBUFLEN];
    ssize_t length;

    length = scnprintf(tmpbuf, TMPBUFLEN, "%u", selinux_checkreqprot);
    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static ssize_t sel_write_checkreqprot(struct file *file, const char __user *buf,
                      size_t count, loff_t *ppos)
{
    char *page = NULL;
    ssize_t length;
    unsigned int new_value;

    length = task_has_security(current, SECURITY__SETCHECKREQPROT);
    if (length)
        goto out;

    length = -ENOMEM;
    if (count >= PAGE_SIZE)
        goto out;

    /* No partial writes. */
    length = -EINVAL;
    if (*ppos != 0)
        goto out;

    length = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    length = -EFAULT;
    if (copy_from_user(page, buf, count))
        goto out;

    length = -EINVAL;
    if (sscanf(page, "%u", &new_value) != 1)
        goto out;

    selinux_checkreqprot = new_value ? 1 : 0;
    length = count;
out:
    free_page((unsigned long) page);
    return length;
}
static const struct file_operations sel_checkreqprot_ops = {
    .read       = sel_read_checkreqprot,
    .write      = sel_write_checkreqprot,
    .llseek     = generic_file_llseek,
};

/*
 * Remaining nodes use transaction based IO methods like nfsd/nfsctl.c
 */
static ssize_t sel_write_access(struct file *file, char *buf, size_t size);
static ssize_t sel_write_create(struct file *file, char *buf, size_t size);
static ssize_t sel_write_relabel(struct file *file, char *buf, size_t size);
static ssize_t sel_write_user(struct file *file, char *buf, size_t size);
static ssize_t sel_write_member(struct file *file, char *buf, size_t size);

static ssize_t (*write_op[])(struct file *, char *, size_t) = {
    [SEL_ACCESS] = sel_write_access,
    [SEL_CREATE] = sel_write_create,
    [SEL_RELABEL] = sel_write_relabel,
    [SEL_USER] = sel_write_user,
    [SEL_MEMBER] = sel_write_member,
    [SEL_CONTEXT] = sel_write_context,
};

static ssize_t selinux_transaction_write(struct file *file, const char __user *buf, size_t size, loff_t *pos)
{
    ino_t ino = file->f_path.dentry->d_inode->i_ino;
    char *data;
    ssize_t rv;

    if (ino >= ARRAY_SIZE(write_op) || !write_op[ino])
        return -EINVAL;

    data = simple_transaction_get(file, buf, size);
    if (IS_ERR(data))
        return PTR_ERR(data);

    rv = write_op[ino](file, data, size);
    if (rv > 0) {
        simple_transaction_set(file, rv);
        rv = size;
    }
    return rv;
}

static const struct file_operations transaction_ops = {
    .write      = selinux_transaction_write,
    .read       = simple_transaction_read,
    .release    = simple_transaction_release,
    .llseek     = generic_file_llseek,
};

/*
 * payload - write methods
 * If the method has a response, the response should be put in buf,
 * and the length returned.  Otherwise return 0 or and -error.
 */

static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
{
    char *scon = NULL, *tcon = NULL;
    u32 ssid, tsid;
    u16 tclass;
    struct av_decision avd;
    ssize_t length;

    length = task_has_security(current, SECURITY__COMPUTE_AV);
    if (length)
        goto out;

    length = -ENOMEM;
    scon = kzalloc(size + 1, GFP_KERNEL);
    if (!scon)
        goto out;

    length = -ENOMEM;
    tcon = kzalloc(size + 1, GFP_KERNEL);
    if (!tcon)
        goto out;

    length = -EINVAL;
    if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
        goto out;

    length = security_context_to_sid(scon, strlen(scon) + 1, &ssid);
    if (length)
        goto out;

    length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid);
    if (length)
        goto out;

    security_compute_av_user(ssid, tsid, tclass, &avd);

    length = scnprintf(buf, SIMPLE_TRANSACTION_LIMIT,
              "%x %x %x %x %u %x",
              avd.allowed, 0xffffffff,
              avd.auditallow, avd.auditdeny,
              avd.seqno, avd.flags);
out:
    kfree(tcon);
    kfree(scon);
    return length;
}

static ssize_t sel_write_create(struct file *file, char *buf, size_t size)
{
    char *scon = NULL, *tcon = NULL;
    char *namebuf = NULL, *objname = NULL;
    u32 ssid, tsid, newsid;
    u16 tclass;
    ssize_t length;
    char *newcon = NULL;
    u32 len;
    int nargs;

    length = task_has_security(current, SECURITY__COMPUTE_CREATE);
    if (length)
        goto out;

    length = -ENOMEM;
    scon = kzalloc(size + 1, GFP_KERNEL);
    if (!scon)
        goto out;

    length = -ENOMEM;
    tcon = kzalloc(size + 1, GFP_KERNEL);
    if (!tcon)
        goto out;

    length = -ENOMEM;
    namebuf = kzalloc(size + 1, GFP_KERNEL);
    if (!namebuf)
        goto out;

    length = -EINVAL;
    nargs = sscanf(buf, "%s %s %hu %s", scon, tcon, &tclass, namebuf);
    if (nargs < 3 || nargs > 4)
        goto out;
    if (nargs == 4) {
        /*
         * If and when the name of new object to be queried contains
         * either whitespace or multibyte characters, they shall be
         * encoded based on the percentage-encoding rule.
         * If not encoded, the sscanf logic picks up only left-half
         * of the supplied name; splitted by a whitespace unexpectedly.
         */
        char   *r, *w;
        int     c1, c2;

        r = w = namebuf;
        do {
            c1 = *r++;
            if (c1 == '+')
                c1 = ' ';
            else if (c1 == '%') {
                c1 = hex_to_bin(*r++);
                if (c1 < 0)
                    goto out;
                c2 = hex_to_bin(*r++);
                if (c2 < 0)
                    goto out;
                c1 = (c1 << 4) | c2;
            }
            *w++ = c1;
        } while (c1 != '\0');

        objname = namebuf;
    }

    length = security_context_to_sid(scon, strlen(scon) + 1, &ssid);
    if (length)
        goto out;

    length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid);
    if (length)
        goto out;

    length = security_transition_sid_user(ssid, tsid, tclass,
                          objname, &newsid);
    if (length)
        goto out;

    length = security_sid_to_context(newsid, &newcon, &len);
    if (length)
        goto out;

    length = -ERANGE;
    if (len > SIMPLE_TRANSACTION_LIMIT) {
        printk(KERN_ERR "SELinux: %s:  context size (%u) exceeds "
            "payload max\n", __func__, len);
        goto out;
    }

    memcpy(buf, newcon, len);
    length = len;
out:
    kfree(newcon);
    kfree(namebuf);
    kfree(tcon);
    kfree(scon);
    return length;
}

static ssize_t sel_write_relabel(struct file *file, char *buf, size_t size)
{
    char *scon = NULL, *tcon = NULL;
    u32 ssid, tsid, newsid;
    u16 tclass;
    ssize_t length;
    char *newcon = NULL;
    u32 len;

    length = task_has_security(current, SECURITY__COMPUTE_RELABEL);
    if (length)
        goto out;

    length = -ENOMEM;
    scon = kzalloc(size + 1, GFP_KERNEL);
    if (!scon)
        goto out;

    length = -ENOMEM;
    tcon = kzalloc(size + 1, GFP_KERNEL);
    if (!tcon)
        goto out;

    length = -EINVAL;
    if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
        goto out;

    length = security_context_to_sid(scon, strlen(scon) + 1, &ssid);
    if (length)
        goto out;

    length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid);
    if (length)
        goto out;

    length = security_change_sid(ssid, tsid, tclass, &newsid);
    if (length)
        goto out;

    length = security_sid_to_context(newsid, &newcon, &len);
    if (length)
        goto out;

    length = -ERANGE;
    if (len > SIMPLE_TRANSACTION_LIMIT)
        goto out;

    memcpy(buf, newcon, len);
    length = len;
out:
    kfree(newcon);
    kfree(tcon);
    kfree(scon);
    return length;
}

static ssize_t sel_write_user(struct file *file, char *buf, size_t size)
{
    char *con = NULL, *user = NULL, *ptr;
    u32 sid, *sids = NULL;
    ssize_t length;
    char *newcon;
    int i, rc;
    u32 len, nsids;

    length = task_has_security(current, SECURITY__COMPUTE_USER);
    if (length)
        goto out;

    length = -ENOMEM;
    con = kzalloc(size + 1, GFP_KERNEL);
    if (!con)
        goto out;

    length = -ENOMEM;
    user = kzalloc(size + 1, GFP_KERNEL);
    if (!user)
        goto out;

    length = -EINVAL;
    if (sscanf(buf, "%s %s", con, user) != 2)
        goto out;

    length = security_context_to_sid(con, strlen(con) + 1, &sid);
    if (length)
        goto out;

    length = security_get_user_sids(sid, user, &sids, &nsids);
    if (length)
        goto out;

    length = sprintf(buf, "%u", nsids) + 1;
    ptr = buf + length;
    for (i = 0; i < nsids; i++) {
        rc = security_sid_to_context(sids[i], &newcon, &len);
        if (rc) {
            length = rc;
            goto out;
        }
        if ((length + len) >= SIMPLE_TRANSACTION_LIMIT) {
            kfree(newcon);
            length = -ERANGE;
            goto out;
        }
        memcpy(ptr, newcon, len);
        kfree(newcon);
        ptr += len;
        length += len;
    }
out:
    kfree(sids);
    kfree(user);
    kfree(con);
    return length;
}

static ssize_t sel_write_member(struct file *file, char *buf, size_t size)
{
    char *scon = NULL, *tcon = NULL;
    u32 ssid, tsid, newsid;
    u16 tclass;
    ssize_t length;
    char *newcon = NULL;
    u32 len;

    length = task_has_security(current, SECURITY__COMPUTE_MEMBER);
    if (length)
        goto out;

    length = -ENOMEM;
    scon = kzalloc(size + 1, GFP_KERNEL);
    if (!scon)
        goto out;

    length = -ENOMEM;
    tcon = kzalloc(size + 1, GFP_KERNEL);
    if (!tcon)
        goto out;

    length = -EINVAL;
    if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
        goto out;

    length = security_context_to_sid(scon, strlen(scon) + 1, &ssid);
    if (length)
        goto out;

    length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid);
    if (length)
        goto out;

    length = security_member_sid(ssid, tsid, tclass, &newsid);
    if (length)
        goto out;

    length = security_sid_to_context(newsid, &newcon, &len);
    if (length)
        goto out;

    length = -ERANGE;
    if (len > SIMPLE_TRANSACTION_LIMIT) {
        printk(KERN_ERR "SELinux: %s:  context size (%u) exceeds "
            "payload max\n", __func__, len);
        goto out;
    }

    memcpy(buf, newcon, len);
    length = len;
out:
    kfree(newcon);
    kfree(tcon);
    kfree(scon);
    return length;
}

static struct inode *sel_make_inode(struct super_block *sb, int mode)
{
    struct inode *ret = new_inode(sb);

    if (ret) {
        ret->i_mode = mode;
        ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
    }
    return ret;
}

static ssize_t sel_read_bool(struct file *filep, char __user *buf,
                 size_t count, loff_t *ppos)
{
    char *page = NULL;
    ssize_t length;
    ssize_t ret;
    int cur_enforcing;
    struct inode *inode = filep->f_path.dentry->d_inode;
    unsigned index = inode->i_ino & SEL_INO_MASK;
    const char *name = filep->f_path.dentry->d_name.name;

    mutex_lock(&sel_mutex);

    ret = -EINVAL;
    if (index >= bool_num || strcmp(name, bool_pending_names[index]))
        goto out;

    ret = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    cur_enforcing = security_get_bool_value(index);
    if (cur_enforcing < 0) {
        ret = cur_enforcing;
        goto out;
    }
    length = scnprintf(page, PAGE_SIZE, "%d %d", cur_enforcing,
              bool_pending_values[index]);
    ret = simple_read_from_buffer(buf, count, ppos, page, length);
out:
    mutex_unlock(&sel_mutex);
    free_page((unsigned long)page);
    return ret;
}

static ssize_t sel_write_bool(struct file *filep, const char __user *buf,
                  size_t count, loff_t *ppos)
{
    char *page = NULL;
    ssize_t length;
    int new_value;
    struct inode *inode = filep->f_path.dentry->d_inode;
    unsigned index = inode->i_ino & SEL_INO_MASK;
    const char *name = filep->f_path.dentry->d_name.name;

    mutex_lock(&sel_mutex);

    length = task_has_security(current, SECURITY__SETBOOL);
    if (length)
        goto out;

    length = -EINVAL;
    if (index >= bool_num || strcmp(name, bool_pending_names[index]))
        goto out;

    length = -ENOMEM;
    if (count >= PAGE_SIZE)
        goto out;

    /* No partial writes. */
    length = -EINVAL;
    if (*ppos != 0)
        goto out;

    length = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    length = -EFAULT;
    if (copy_from_user(page, buf, count))
        goto out;

    length = -EINVAL;
    if (sscanf(page, "%d", &new_value) != 1)
        goto out;

    if (new_value)
        new_value = 1;

    bool_pending_values[index] = new_value;
    length = count;

out:
    mutex_unlock(&sel_mutex);
    free_page((unsigned long) page);
    return length;
}

static const struct file_operations sel_bool_ops = {
    .read       = sel_read_bool,
    .write      = sel_write_bool,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_commit_bools_write(struct file *filep,
                      const char __user *buf,
                      size_t count, loff_t *ppos)
{
    char *page = NULL;
    ssize_t length;
    int new_value;

    mutex_lock(&sel_mutex);

    length = task_has_security(current, SECURITY__SETBOOL);
    if (length)
        goto out;

    length = -ENOMEM;
    if (count >= PAGE_SIZE)
        goto out;

    /* No partial writes. */
    length = -EINVAL;
    if (*ppos != 0)
        goto out;

    length = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    length = -EFAULT;
    if (copy_from_user(page, buf, count))
        goto out;

    length = -EINVAL;
    if (sscanf(page, "%d", &new_value) != 1)
        goto out;

    length = 0;
    if (new_value && bool_pending_values)
        length = security_set_bools(bool_num, bool_pending_values);

    if (!length)
        length = count;

out:
    mutex_unlock(&sel_mutex);
    free_page((unsigned long) page);
    return length;
}

static const struct file_operations sel_commit_bools_ops = {
    .write      = sel_commit_bools_write,
    .llseek     = generic_file_llseek,
};

static void sel_remove_entries(struct dentry *de)
{
    struct list_head *node;

    spin_lock(&de->d_lock);
    node = de->d_subdirs.next;
    while (node != &de->d_subdirs) {
        struct dentry *d = list_entry(node, struct dentry, d_u.d_child);

        spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
        list_del_init(node);

        if (d->d_inode) {
            dget_dlock(d);
            spin_unlock(&de->d_lock);
            spin_unlock(&d->d_lock);
            d_delete(d);
            simple_unlink(de->d_inode, d);
            dput(d);
            spin_lock(&de->d_lock);
        } else
            spin_unlock(&d->d_lock);
        node = de->d_subdirs.next;
    }

    spin_unlock(&de->d_lock);
}

#define BOOL_DIR_NAME "booleans"

static int sel_make_bools(void)
{
    int i, ret;
    ssize_t len;
    struct dentry *dentry = NULL;
    struct dentry *dir = bool_dir;
    struct inode *inode = NULL;
    struct inode_security_struct *isec;
    char **names = NULL, *page;
    int num;
    int *values = NULL;
    u32 sid;

    /* remove any existing files */
    for (i = 0; i < bool_num; i++)
        kfree(bool_pending_names[i]);
    kfree(bool_pending_names);
    kfree(bool_pending_values);
    bool_num = 0;
    bool_pending_names = NULL;
    bool_pending_values = NULL;

    sel_remove_entries(dir);

    ret = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    ret = security_get_bools(&num, &names, &values);
    if (ret)
        goto out;

    for (i = 0; i < num; i++) {
        ret = -ENOMEM;
        dentry = d_alloc_name(dir, names[i]);
        if (!dentry)
            goto out;

        ret = -ENOMEM;
        inode = sel_make_inode(dir->d_sb, S_IFREG | S_IRUGO | S_IWUSR);
        if (!inode)
            goto out;

        ret = -ENAMETOOLONG;
        len = snprintf(page, PAGE_SIZE, "/%s/%s", BOOL_DIR_NAME, names[i]);
        if (len >= PAGE_SIZE)
            goto out;

        isec = (struct inode_security_struct *)inode->i_security;
        ret = security_genfs_sid("selinuxfs", page, SECCLASS_FILE, &sid);
        if (ret)
            goto out;

        isec->sid = sid;
        isec->initialized = 1;
        inode->i_fop = &sel_bool_ops;
        inode->i_ino = i|SEL_BOOL_INO_OFFSET;
        d_add(dentry, inode);
    }
    bool_num = num;
    bool_pending_names = names;
    bool_pending_values = values;

    free_page((unsigned long)page);
    return 0;
out:
    free_page((unsigned long)page);

    if (names) {
        for (i = 0; i < num; i++)
            kfree(names[i]);
        kfree(names);
    }
    kfree(values);
    sel_remove_entries(dir);

    return ret;
}

#define NULL_FILE_NAME "null"

struct path selinux_null;

static ssize_t sel_read_avc_cache_threshold(struct file *filp, char __user *buf,
                        size_t count, loff_t *ppos)
{
    char tmpbuf[TMPBUFLEN];
    ssize_t length;

    length = scnprintf(tmpbuf, TMPBUFLEN, "%u", avc_cache_threshold);
    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static ssize_t sel_write_avc_cache_threshold(struct file *file,
                         const char __user *buf,
                         size_t count, loff_t *ppos)

{
    char *page = NULL;
    ssize_t ret;
    int new_value;

    ret = task_has_security(current, SECURITY__SETSECPARAM);
    if (ret)
        goto out;

    ret = -ENOMEM;
    if (count >= PAGE_SIZE)
        goto out;

    /* No partial writes. */
    ret = -EINVAL;
    if (*ppos != 0)
        goto out;

    ret = -ENOMEM;
    page = (char *)get_zeroed_page(GFP_KERNEL);
    if (!page)
        goto out;

    ret = -EFAULT;
    if (copy_from_user(page, buf, count))
        goto out;

    ret = -EINVAL;
    if (sscanf(page, "%u", &new_value) != 1)
        goto out;

    avc_cache_threshold = new_value;

    ret = count;
out:
    free_page((unsigned long)page);
    return ret;
}

static ssize_t sel_read_avc_hash_stats(struct file *filp, char __user *buf,
                       size_t count, loff_t *ppos)
{
    char *page;
    ssize_t length;

    page = (char *)__get_free_page(GFP_KERNEL);
    if (!page)
        return -ENOMEM;

    length = avc_get_hash_stats(page);
    if (length >= 0)
        length = simple_read_from_buffer(buf, count, ppos, page, length);
    free_page((unsigned long)page);

    return length;
}

static const struct file_operations sel_avc_cache_threshold_ops = {
    .read       = sel_read_avc_cache_threshold,
    .write      = sel_write_avc_cache_threshold,
    .llseek     = generic_file_llseek,
};

static const struct file_operations sel_avc_hash_stats_ops = {
    .read       = sel_read_avc_hash_stats,
    .llseek     = generic_file_llseek,
};

#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
static struct avc_cache_stats *sel_avc_get_stat_idx(loff_t *idx)
{
    int cpu;

    for (cpu = *idx; cpu < nr_cpu_ids; ++cpu) {
        if (!cpu_possible(cpu))
            continue;
        *idx = cpu + 1;
        return &per_cpu(avc_cache_stats, cpu);
    }
    return NULL;
}

static void *sel_avc_stats_seq_start(struct seq_file *seq, loff_t *pos)
{
    loff_t n = *pos - 1;

    if (*pos == 0)
        return SEQ_START_TOKEN;

    return sel_avc_get_stat_idx(&n);
}

static void *sel_avc_stats_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    return sel_avc_get_stat_idx(pos);
}

static int sel_avc_stats_seq_show(struct seq_file *seq, void *v)
{
    struct avc_cache_stats *st = v;

    if (v == SEQ_START_TOKEN)
        seq_printf(seq, "lookups hits misses allocations reclaims "
               "frees\n");
    else {
        unsigned int lookups = st->lookups;
        unsigned int misses = st->misses;
        unsigned int hits = lookups - misses;
        seq_printf(seq, "%u %u %u %u %u %u\n", lookups,
               hits, misses, st->allocations,
               st->reclaims, st->frees);
    }
    return 0;
}

static void sel_avc_stats_seq_stop(struct seq_file *seq, void *v)
{ }

static const struct seq_operations sel_avc_cache_stats_seq_ops = {
    .start      = sel_avc_stats_seq_start,
    .next       = sel_avc_stats_seq_next,
    .show       = sel_avc_stats_seq_show,
    .stop       = sel_avc_stats_seq_stop,
};

static int sel_open_avc_cache_stats(struct inode *inode, struct file *file)
{
    return seq_open(file, &sel_avc_cache_stats_seq_ops);
}

static const struct file_operations sel_avc_cache_stats_ops = {
    .open       = sel_open_avc_cache_stats,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
};
#endif

static int sel_make_avc_files(struct dentry *dir)
{
    int i;
    static struct tree_descr files[] = {
        { "cache_threshold",
          &sel_avc_cache_threshold_ops, S_IRUGO|S_IWUSR },
        { "hash_stats", &sel_avc_hash_stats_ops, S_IRUGO },
#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
        { "cache_stats", &sel_avc_cache_stats_ops, S_IRUGO },
#endif
    };

    for (i = 0; i < ARRAY_SIZE(files); i++) {
        struct inode *inode;
        struct dentry *dentry;

        dentry = d_alloc_name(dir, files[i].name);
        if (!dentry)
            return -ENOMEM;

        inode = sel_make_inode(dir->d_sb, S_IFREG|files[i].mode);
        if (!inode)
            return -ENOMEM;

        inode->i_fop = files[i].ops;
        inode->i_ino = ++sel_last_ino;
        d_add(dentry, inode);
    }

    return 0;
}

static ssize_t sel_read_initcon(struct file *file, char __user *buf,
                size_t count, loff_t *ppos)
{
    struct inode *inode;
    char *con;
    u32 sid, len;
    ssize_t ret;

    inode = file->f_path.dentry->d_inode;
    sid = inode->i_ino&SEL_INO_MASK;
    ret = security_sid_to_context(sid, &con, &len);
    if (ret)
        return ret;

    ret = simple_read_from_buffer(buf, count, ppos, con, len);
    kfree(con);
    return ret;
}

static const struct file_operations sel_initcon_ops = {
    .read       = sel_read_initcon,
    .llseek     = generic_file_llseek,
};

static int sel_make_initcon_files(struct dentry *dir)
{
    int i;

    for (i = 1; i <= SECINITSID_NUM; i++) {
        struct inode *inode;
        struct dentry *dentry;
        dentry = d_alloc_name(dir, security_get_initial_sid_context(i));
        if (!dentry)
            return -ENOMEM;

        inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
        if (!inode)
            return -ENOMEM;

        inode->i_fop = &sel_initcon_ops;
        inode->i_ino = i|SEL_INITCON_INO_OFFSET;
        d_add(dentry, inode);
    }

    return 0;
}

static inline unsigned long sel_class_to_ino(u16 class)
{
    return (class * (SEL_VEC_MAX + 1)) | SEL_CLASS_INO_OFFSET;
}

static inline u16 sel_ino_to_class(unsigned long ino)
{
    return (ino & SEL_INO_MASK) / (SEL_VEC_MAX + 1);
}

static inline unsigned long sel_perm_to_ino(u16 class, u32 perm)
{
    return (class * (SEL_VEC_MAX + 1) + perm) | SEL_CLASS_INO_OFFSET;
}

static inline u32 sel_ino_to_perm(unsigned long ino)
{
    return (ino & SEL_INO_MASK) % (SEL_VEC_MAX + 1);
}

static ssize_t sel_read_class(struct file *file, char __user *buf,
                size_t count, loff_t *ppos)
{
    unsigned long ino = file->f_path.dentry->d_inode->i_ino;
    char res[TMPBUFLEN];
    ssize_t len = snprintf(res, sizeof(res), "%d", sel_ino_to_class(ino));
    return simple_read_from_buffer(buf, count, ppos, res, len);
}

static const struct file_operations sel_class_ops = {
    .read       = sel_read_class,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_read_perm(struct file *file, char __user *buf,
                size_t count, loff_t *ppos)
{
    unsigned long ino = file->f_path.dentry->d_inode->i_ino;
    char res[TMPBUFLEN];
    ssize_t len = snprintf(res, sizeof(res), "%d", sel_ino_to_perm(ino));
    return simple_read_from_buffer(buf, count, ppos, res, len);
}

static const struct file_operations sel_perm_ops = {
    .read       = sel_read_perm,
    .llseek     = generic_file_llseek,
};

static ssize_t sel_read_policycap(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos)
{
    int value;
    char tmpbuf[TMPBUFLEN];
    ssize_t length;
    unsigned long i_ino = file->f_path.dentry->d_inode->i_ino;

    value = security_policycap_supported(i_ino & SEL_INO_MASK);
    length = scnprintf(tmpbuf, TMPBUFLEN, "%d", value);

    return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static const struct file_operations sel_policycap_ops = {
    .read       = sel_read_policycap,
    .llseek     = generic_file_llseek,
};

static int sel_make_perm_files(char *objclass, int classvalue,
                struct dentry *dir)
{
    int i, rc, nperms;
    char **perms;

    rc = security_get_permissions(objclass, &perms, &nperms);
    if (rc)
        return rc;

    for (i = 0; i < nperms; i++) {
        struct inode *inode;
        struct dentry *dentry;

        rc = -ENOMEM;
        dentry = d_alloc_name(dir, perms[i]);
        if (!dentry)
            goto out;

        rc = -ENOMEM;
        inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
        if (!inode)
            goto out;

        inode->i_fop = &sel_perm_ops;
        /* i+1 since perm values are 1-indexed */
        inode->i_ino = sel_perm_to_ino(classvalue, i + 1);
        d_add(dentry, inode);
    }
    rc = 0;
out:
    for (i = 0; i < nperms; i++)
        kfree(perms[i]);
    kfree(perms);
    return rc;
}

static int sel_make_class_dir_entries(char *classname, int index,
                    struct dentry *dir)
{
    struct dentry *dentry = NULL;
    struct inode *inode = NULL;
    int rc;

    dentry = d_alloc_name(dir, "index");
    if (!dentry)
        return -ENOMEM;

    inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
    if (!inode)
        return -ENOMEM;

    inode->i_fop = &sel_class_ops;
    inode->i_ino = sel_class_to_ino(index);
    d_add(dentry, inode);

    dentry = sel_make_dir(dir, "perms", &last_class_ino);
    if (IS_ERR(dentry))
        return PTR_ERR(dentry);

    rc = sel_make_perm_files(classname, index, dentry);

    return rc;
}

static void sel_remove_classes(void)
{
    struct list_head *class_node;

    list_for_each(class_node, &class_dir->d_subdirs) {
        struct dentry *class_subdir = list_entry(class_node,
                    struct dentry, d_u.d_child);
        struct list_head *class_subdir_node;

        list_for_each(class_subdir_node, &class_subdir->d_subdirs) {
            struct dentry *d = list_entry(class_subdir_node,
                        struct dentry, d_u.d_child);

            if (d->d_inode)
                if (d->d_inode->i_mode & S_IFDIR)
                    sel_remove_entries(d);
        }

        sel_remove_entries(class_subdir);
    }

    sel_remove_entries(class_dir);
}

static int sel_make_classes(void)
{
    int rc, nclasses, i;
    char **classes;

    /* delete any existing entries */
    sel_remove_classes();

    rc = security_get_classes(&classes, &nclasses);
    if (rc)
        return rc;

    /* +2 since classes are 1-indexed */
    last_class_ino = sel_class_to_ino(nclasses + 2);

    for (i = 0; i < nclasses; i++) {
        struct dentry *class_name_dir;

        class_name_dir = sel_make_dir(class_dir, classes[i],
                &last_class_ino);
        if (IS_ERR(class_name_dir)) {
            rc = PTR_ERR(class_name_dir);
            goto out;
        }

        /* i+1 since class values are 1-indexed */
        rc = sel_make_class_dir_entries(classes[i], i + 1,
                class_name_dir);
        if (rc)
            goto out;
    }
    rc = 0;
out:
    for (i = 0; i < nclasses; i++)
        kfree(classes[i]);
    kfree(classes);
    return rc;
}

static int sel_make_policycap(void)
{
    unsigned int iter;
    struct dentry *dentry = NULL;
    struct inode *inode = NULL;

    sel_remove_entries(policycap_dir);

    for (iter = 0; iter <= POLICYDB_CAPABILITY_MAX; iter++) {
        if (iter < ARRAY_SIZE(policycap_names))
            dentry = d_alloc_name(policycap_dir,
                          policycap_names[iter]);
        else
            dentry = d_alloc_name(policycap_dir, "unknown");

        if (dentry == NULL)
            return -ENOMEM;

        inode = sel_make_inode(policycap_dir->d_sb, S_IFREG | S_IRUGO);
        if (inode == NULL)
            return -ENOMEM;

        inode->i_fop = &sel_policycap_ops;
        inode->i_ino = iter | SEL_POLICYCAP_INO_OFFSET;
        d_add(dentry, inode);
    }

    return 0;
}

static struct dentry *sel_make_dir(struct dentry *dir, const char *name,
            unsigned long *ino)
{
    struct dentry *dentry = d_alloc_name(dir, name);
    struct inode *inode;

    if (!dentry)
        return ERR_PTR(-ENOMEM);

    inode = sel_make_inode(dir->d_sb, S_IFDIR | S_IRUGO | S_IXUGO);
    if (!inode) {
        dput(dentry);
        return ERR_PTR(-ENOMEM);
    }

    inode->i_op = &simple_dir_inode_operations;
    inode->i_fop = &simple_dir_operations;
    inode->i_ino = ++(*ino);
    /* directory inodes start off with i_nlink == 2 (for "." entry) */
    inc_nlink(inode);
    d_add(dentry, inode);
    /* bump link count on parent directory, too */
    inc_nlink(dir->d_inode);

    return dentry;
}

static int sel_fill_super(struct super_block *sb, void *data, int silent)
{
    int ret;
    struct dentry *dentry;
    struct inode *inode;
    struct inode_security_struct *isec;

    static struct tree_descr selinux_files[] = {
        [SEL_LOAD] = {"load", &sel_load_ops, S_IRUSR|S_IWUSR},
        [SEL_ENFORCE] = {"enforce", &sel_enforce_ops, S_IRUGO|S_IWUSR},
        [SEL_CONTEXT] = {"context", &transaction_ops, S_IRUGO|S_IWUGO},
        [SEL_ACCESS] = {"access", &transaction_ops, S_IRUGO|S_IWUGO},
        [SEL_CREATE] = {"create", &transaction_ops, S_IRUGO|S_IWUGO},
        [SEL_RELABEL] = {"relabel", &transaction_ops, S_IRUGO|S_IWUGO},
        [SEL_USER] = {"user", &transaction_ops, S_IRUGO|S_IWUGO},
        [SEL_POLICYVERS] = {"policyvers", &sel_policyvers_ops, S_IRUGO},
        [SEL_COMMIT_BOOLS] = {"commit_pending_bools", &sel_commit_bools_ops, S_IWUSR},
        [SEL_MLS] = {"mls", &sel_mls_ops, S_IRUGO},
        [SEL_DISABLE] = {"disable", &sel_disable_ops, S_IWUSR},
        [SEL_MEMBER] = {"member", &transaction_ops, S_IRUGO|S_IWUGO},
        [SEL_CHECKREQPROT] = {"checkreqprot", &sel_checkreqprot_ops, S_IRUGO|S_IWUSR},
        [SEL_REJECT_UNKNOWN] = {"reject_unknown", &sel_handle_unknown_ops, S_IRUGO},
        [SEL_DENY_UNKNOWN] = {"deny_unknown", &sel_handle_unknown_ops, S_IRUGO},
        [SEL_STATUS] = {"status", &sel_handle_status_ops, S_IRUGO},
        [SEL_POLICY] = {"policy", &sel_policy_ops, S_IRUGO},
        /* last one */ {""}
    };
    ret = simple_fill_super(sb, SELINUX_MAGIC, selinux_files);
    if (ret)
        goto err;

    bool_dir = sel_make_dir(sb->s_root, BOOL_DIR_NAME, &sel_last_ino);
    if (IS_ERR(bool_dir)) {
        ret = PTR_ERR(bool_dir);
        bool_dir = NULL;
        goto err;
    }

    ret = -ENOMEM;
    dentry = d_alloc_name(sb->s_root, NULL_FILE_NAME);
    if (!dentry)
        goto err;

    ret = -ENOMEM;
    inode = sel_make_inode(sb, S_IFCHR | S_IRUGO | S_IWUGO);
    if (!inode)
        goto err;

    inode->i_ino = ++sel_last_ino;
    isec = (struct inode_security_struct *)inode->i_security;
    isec->sid = SECINITSID_DEVNULL;
    isec->sclass = SECCLASS_CHR_FILE;
    isec->initialized = 1;

    init_special_inode(inode, S_IFCHR | S_IRUGO | S_IWUGO, MKDEV(MEM_MAJOR, 3));
    d_add(dentry, inode);
    selinux_null.dentry = dentry;

    dentry = sel_make_dir(sb->s_root, "avc", &sel_last_ino);
    if (IS_ERR(dentry)) {
        ret = PTR_ERR(dentry);
        goto err;
    }

    ret = sel_make_avc_files(dentry);
    if (ret)
        goto err;

    dentry = sel_make_dir(sb->s_root, "initial_contexts", &sel_last_ino);
    if (IS_ERR(dentry)) {
        ret = PTR_ERR(dentry);
        goto err;
    }

    ret = sel_make_initcon_files(dentry);
    if (ret)
        goto err;

    class_dir = sel_make_dir(sb->s_root, "class", &sel_last_ino);
    if (IS_ERR(class_dir)) {
        ret = PTR_ERR(class_dir);
        class_dir = NULL;
        goto err;
    }

    policycap_dir = sel_make_dir(sb->s_root, "policy_capabilities", &sel_last_ino);
    if (IS_ERR(policycap_dir)) {
        ret = PTR_ERR(policycap_dir);
        policycap_dir = NULL;
        goto err;
    }
    return 0;
err:
    printk(KERN_ERR "SELinux: %s:  failed while creating inodes\n",
        __func__);
    return ret;
}

static struct dentry *sel_mount(struct file_system_type *fs_type,
              int flags, const char *dev_name, void *data)
{
    return mount_single(fs_type, flags, data, sel_fill_super);
}

static struct file_system_type sel_fs_type = {
    .name       = "selinuxfs",
    .mount      = sel_mount,
    .kill_sb    = kill_litter_super,
};

struct vfsmount *selinuxfs_mount;
static struct kobject *selinuxfs_kobj;

static int __init init_sel_fs(void)
{
    int err;

    if (!selinux_enabled)
        return 0;

    selinuxfs_kobj = kobject_create_and_add("selinux", fs_kobj);
    if (!selinuxfs_kobj)
        return -ENOMEM;

    err = register_filesystem(&sel_fs_type);
    if (err) {
        kobject_put(selinuxfs_kobj);
        return err;
    }

    selinux_null.mnt = selinuxfs_mount = kern_mount(&sel_fs_type);
    if (IS_ERR(selinuxfs_mount)) {
        printk(KERN_ERR "selinuxfs:  could not mount!\n");
        err = PTR_ERR(selinuxfs_mount);
        selinuxfs_mount = NULL;
    }

    return err;
}

__initcall(init_sel_fs);

#ifdef CONFIG_SECURITY_SELINUX_DISABLE
void exit_sel_fs(void)
{
    kobject_put(selinuxfs_kobj);
    kern_unmount(selinuxfs_mount);
    unregister_filesystem(&sel_fs_type);
}
#endif