CRED: Use RCU to access another task's creds and to release a task's own creds

[linux-2.6-block.git] / security / smack / smack_lsm.c

/*
 *  Simplified MAC Kernel (smack) security module
 *
 *  This file contains the smack hook function implementations.
 *
 *  Author:
 *      Casey Schaufler <casey@schaufler-ca.com>
 *
 *  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 version 2,
 *      as published by the Free Software Foundation.
 */

#include <linux/xattr.h>
#include <linux/pagemap.h>
#include <linux/mount.h>
#include <linux/stat.h>
#include <linux/ext2_fs.h>
#include <linux/kd.h>
#include <asm/ioctls.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/mutex.h>
#include <linux/pipe_fs_i.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <linux/audit.h>

#include "smack.h"

#define task_security(task)     (task_cred_xxx((task), security))

/*
 * I hope these are the hokeyist lines of code in the module. Casey.
 */
#define DEVPTS_SUPER_MAGIC      0x1cd1
#define SOCKFS_MAGIC            0x534F434B
#define TMPFS_MAGIC             0x01021994

/**
 * smk_fetch - Fetch the smack label from a file.
 * @ip: a pointer to the inode
 * @dp: a pointer to the dentry
 *
 * Returns a pointer to the master list entry for the Smack label
 * or NULL if there was no label to fetch.
 */
static char *smk_fetch(struct inode *ip, struct dentry *dp)
{
        int rc;
        char in[SMK_LABELLEN];

        if (ip->i_op->getxattr == NULL)
                return NULL;

        rc = ip->i_op->getxattr(dp, XATTR_NAME_SMACK, in, SMK_LABELLEN);
        if (rc < 0)
                return NULL;

        return smk_import(in, rc);
}

/**
 * new_inode_smack - allocate an inode security blob
 * @smack: a pointer to the Smack label to use in the blob
 *
 * Returns the new blob or NULL if there's no memory available
 */
struct inode_smack *new_inode_smack(char *smack)
{
        struct inode_smack *isp;

        isp = kzalloc(sizeof(struct inode_smack), GFP_KERNEL);
        if (isp == NULL)
                return NULL;

        isp->smk_inode = smack;
        isp->smk_flags = 0;
        mutex_init(&isp->smk_lock);

        return isp;
}

/*
 * LSM hooks.
 * We he, that is fun!
 */

/**
 * smack_ptrace_may_access - Smack approval on PTRACE_ATTACH
 * @ctp: child task pointer
 *
 * Returns 0 if access is OK, an error code otherwise
 *
 * Do the capability checks, and require read and write.
 */
static int smack_ptrace_may_access(struct task_struct *ctp, unsigned int mode)
{
        int rc;

        rc = cap_ptrace_may_access(ctp, mode);
        if (rc != 0)
                return rc;

        rc = smk_access(current->cred->security, ctp->cred->security,
                        MAY_READWRITE);
        if (rc != 0 && capable(CAP_MAC_OVERRIDE))
                return 0;
        return rc;
}

/**
 * smack_ptrace_traceme - Smack approval on PTRACE_TRACEME
 * @ptp: parent task pointer
 *
 * Returns 0 if access is OK, an error code otherwise
 *
 * Do the capability checks, and require read and write.
 */
static int smack_ptrace_traceme(struct task_struct *ptp)
{
        int rc;

        rc = cap_ptrace_traceme(ptp);
        if (rc != 0)
                return rc;

        rc = smk_access(ptp->cred->security, current->cred->security,
                        MAY_READWRITE);
        if (rc != 0 && has_capability(ptp, CAP_MAC_OVERRIDE))
                return 0;
        return rc;
}

/**
 * smack_syslog - Smack approval on syslog
 * @type: message type
 *
 * Require that the task has the floor label
 *
 * Returns 0 on success, error code otherwise.
 */
static int smack_syslog(int type)
{
        int rc;
        char *sp = current_security();

        rc = cap_syslog(type);
        if (rc != 0)
                return rc;

        if (capable(CAP_MAC_OVERRIDE))
                return 0;

         if (sp != smack_known_floor.smk_known)
                rc = -EACCES;

        return rc;
}


/*
 * Superblock Hooks.
 */

/**
 * smack_sb_alloc_security - allocate a superblock blob
 * @sb: the superblock getting the blob
 *
 * Returns 0 on success or -ENOMEM on error.
 */
static int smack_sb_alloc_security(struct super_block *sb)
{
        struct superblock_smack *sbsp;

        sbsp = kzalloc(sizeof(struct superblock_smack), GFP_KERNEL);

        if (sbsp == NULL)
                return -ENOMEM;

        sbsp->smk_root = smack_known_floor.smk_known;
        sbsp->smk_default = smack_known_floor.smk_known;
        sbsp->smk_floor = smack_known_floor.smk_known;
        sbsp->smk_hat = smack_known_hat.smk_known;
        sbsp->smk_initialized = 0;
        spin_lock_init(&sbsp->smk_sblock);

        sb->s_security = sbsp;

        return 0;
}

/**
 * smack_sb_free_security - free a superblock blob
 * @sb: the superblock getting the blob
 *
 */
static void smack_sb_free_security(struct super_block *sb)
{
        kfree(sb->s_security);
        sb->s_security = NULL;
}

/**
 * smack_sb_copy_data - copy mount options data for processing
 * @type: file system type
 * @orig: where to start
 * @smackopts
 *
 * Returns 0 on success or -ENOMEM on error.
 *
 * Copy the Smack specific mount options out of the mount
 * options list.
 */
static int smack_sb_copy_data(char *orig, char *smackopts)
{
        char *cp, *commap, *otheropts, *dp;

        otheropts = (char *)get_zeroed_page(GFP_KERNEL);
        if (otheropts == NULL)
                return -ENOMEM;

        for (cp = orig, commap = orig; commap != NULL; cp = commap + 1) {
                if (strstr(cp, SMK_FSDEFAULT) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSFLOOR) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSHAT) == cp)
                        dp = smackopts;
                else if (strstr(cp, SMK_FSROOT) == cp)
                        dp = smackopts;
                else
                        dp = otheropts;

                commap = strchr(cp, ',');
                if (commap != NULL)
                        *commap = '\0';

                if (*dp != '\0')
                        strcat(dp, ",");
                strcat(dp, cp);
        }

        strcpy(orig, otheropts);
        free_page((unsigned long)otheropts);

        return 0;
}

/**
 * smack_sb_kern_mount - Smack specific mount processing
 * @sb: the file system superblock
 * @data: the smack mount options
 *
 * Returns 0 on success, an error code on failure
 */
static int smack_sb_kern_mount(struct super_block *sb, void *data)
{
        struct dentry *root = sb->s_root;
        struct inode *inode = root->d_inode;
        struct superblock_smack *sp = sb->s_security;
        struct inode_smack *isp;
        char *op;
        char *commap;
        char *nsp;

        spin_lock(&sp->smk_sblock);
        if (sp->smk_initialized != 0) {
                spin_unlock(&sp->smk_sblock);
                return 0;
        }
        sp->smk_initialized = 1;
        spin_unlock(&sp->smk_sblock);

        for (op = data; op != NULL; op = commap) {
                commap = strchr(op, ',');
                if (commap != NULL)
                        *commap++ = '\0';

                if (strncmp(op, SMK_FSHAT, strlen(SMK_FSHAT)) == 0) {
                        op += strlen(SMK_FSHAT);
                        nsp = smk_import(op, 0);
                        if (nsp != NULL)
                                sp->smk_hat = nsp;
                } else if (strncmp(op, SMK_FSFLOOR, strlen(SMK_FSFLOOR)) == 0) {
                        op += strlen(SMK_FSFLOOR);
                        nsp = smk_import(op, 0);
                        if (nsp != NULL)
                                sp->smk_floor = nsp;
                } else if (strncmp(op, SMK_FSDEFAULT,
                                   strlen(SMK_FSDEFAULT)) == 0) {
                        op += strlen(SMK_FSDEFAULT);
                        nsp = smk_import(op, 0);
                        if (nsp != NULL)
                                sp->smk_default = nsp;
                } else if (strncmp(op, SMK_FSROOT, strlen(SMK_FSROOT)) == 0) {
                        op += strlen(SMK_FSROOT);
                        nsp = smk_import(op, 0);
                        if (nsp != NULL)
                                sp->smk_root = nsp;
                }
        }

        /*
         * Initialize the root inode.
         */
        isp = inode->i_security;
        if (isp == NULL)
                inode->i_security = new_inode_smack(sp->smk_root);
        else
                isp->smk_inode = sp->smk_root;

        return 0;
}

/**
 * smack_sb_statfs - Smack check on statfs
 * @dentry: identifies the file system in question
 *
 * Returns 0 if current can read the floor of the filesystem,
 * and error code otherwise
 */
static int smack_sb_statfs(struct dentry *dentry)
{
        struct superblock_smack *sbp = dentry->d_sb->s_security;

        return smk_curacc(sbp->smk_floor, MAY_READ);
}

/**
 * smack_sb_mount - Smack check for mounting
 * @dev_name: unused
 * @nd: mount point
 * @type: unused
 * @flags: unused
 * @data: unused
 *
 * Returns 0 if current can write the floor of the filesystem
 * being mounted on, an error code otherwise.
 */
static int smack_sb_mount(char *dev_name, struct path *path,
                          char *type, unsigned long flags, void *data)
{
        struct superblock_smack *sbp = path->mnt->mnt_sb->s_security;

        return smk_curacc(sbp->smk_floor, MAY_WRITE);
}

/**
 * smack_sb_umount - Smack check for unmounting
 * @mnt: file system to unmount
 * @flags: unused
 *
 * Returns 0 if current can write the floor of the filesystem
 * being unmounted, an error code otherwise.
 */
static int smack_sb_umount(struct vfsmount *mnt, int flags)
{
        struct superblock_smack *sbp;

        sbp = mnt->mnt_sb->s_security;

        return smk_curacc(sbp->smk_floor, MAY_WRITE);
}

/*
 * Inode hooks
 */

/**
 * smack_inode_alloc_security - allocate an inode blob
 * @inode - the inode in need of a blob
 *
 * Returns 0 if it gets a blob, -ENOMEM otherwise
 */
static int smack_inode_alloc_security(struct inode *inode)
{
        inode->i_security = new_inode_smack(current_security());
        if (inode->i_security == NULL)
                return -ENOMEM;
        return 0;
}

/**
 * smack_inode_free_security - free an inode blob
 * @inode - the inode with a blob
 *
 * Clears the blob pointer in inode
 */
static void smack_inode_free_security(struct inode *inode)
{
        kfree(inode->i_security);
        inode->i_security = NULL;
}

/**
 * smack_inode_init_security - copy out the smack from an inode
 * @inode: the inode
 * @dir: unused
 * @name: where to put the attribute name
 * @value: where to put the attribute value
 * @len: where to put the length of the attribute
 *
 * Returns 0 if it all works out, -ENOMEM if there's no memory
 */
static int smack_inode_init_security(struct inode *inode, struct inode *dir,
                                     char **name, void **value, size_t *len)
{
        char *isp = smk_of_inode(inode);

        if (name) {
                *name = kstrdup(XATTR_SMACK_SUFFIX, GFP_KERNEL);
                if (*name == NULL)
                        return -ENOMEM;
        }

        if (value) {
                *value = kstrdup(isp, GFP_KERNEL);
                if (*value == NULL)
                        return -ENOMEM;
        }

        if (len)
                *len = strlen(isp) + 1;

        return 0;
}

/**
 * smack_inode_link - Smack check on link
 * @old_dentry: the existing object
 * @dir: unused
 * @new_dentry: the new object
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_link(struct dentry *old_dentry, struct inode *dir,
                            struct dentry *new_dentry)
{
        int rc;
        char *isp;

        isp = smk_of_inode(old_dentry->d_inode);
        rc = smk_curacc(isp, MAY_WRITE);

        if (rc == 0 && new_dentry->d_inode != NULL) {
                isp = smk_of_inode(new_dentry->d_inode);
                rc = smk_curacc(isp, MAY_WRITE);
        }

        return rc;
}

/**
 * smack_inode_unlink - Smack check on inode deletion
 * @dir: containing directory object
 * @dentry: file to unlink
 *
 * Returns 0 if current can write the containing directory
 * and the object, error code otherwise
 */
static int smack_inode_unlink(struct inode *dir, struct dentry *dentry)
{
        struct inode *ip = dentry->d_inode;
        int rc;

        /*
         * You need write access to the thing you're unlinking
         */
        rc = smk_curacc(smk_of_inode(ip), MAY_WRITE);
        if (rc == 0)
                /*
                 * You also need write access to the containing directory
                 */
                rc = smk_curacc(smk_of_inode(dir), MAY_WRITE);

        return rc;
}

/**
 * smack_inode_rmdir - Smack check on directory deletion
 * @dir: containing directory object
 * @dentry: directory to unlink
 *
 * Returns 0 if current can write the containing directory
 * and the directory, error code otherwise
 */
static int smack_inode_rmdir(struct inode *dir, struct dentry *dentry)
{
        int rc;

        /*
         * You need write access to the thing you're removing
         */
        rc = smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE);
        if (rc == 0)
                /*
                 * You also need write access to the containing directory
                 */
                rc = smk_curacc(smk_of_inode(dir), MAY_WRITE);

        return rc;
}

/**
 * smack_inode_rename - Smack check on rename
 * @old_inode: the old directory
 * @old_dentry: unused
 * @new_inode: the new directory
 * @new_dentry: unused
 *
 * Read and write access is required on both the old and
 * new directories.
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_rename(struct inode *old_inode,
                              struct dentry *old_dentry,
                              struct inode *new_inode,
                              struct dentry *new_dentry)
{
        int rc;
        char *isp;

        isp = smk_of_inode(old_dentry->d_inode);
        rc = smk_curacc(isp, MAY_READWRITE);

        if (rc == 0 && new_dentry->d_inode != NULL) {
                isp = smk_of_inode(new_dentry->d_inode);
                rc = smk_curacc(isp, MAY_READWRITE);
        }

        return rc;
}

/**
 * smack_inode_permission - Smack version of permission()
 * @inode: the inode in question
 * @mask: the access requested
 * @nd: unused
 *
 * This is the important Smack hook.
 *
 * Returns 0 if access is permitted, -EACCES otherwise
 */
static int smack_inode_permission(struct inode *inode, int mask)
{
        /*
         * No permission to check. Existence test. Yup, it's there.
         */
        if (mask == 0)
                return 0;

        return smk_curacc(smk_of_inode(inode), mask);
}

/**
 * smack_inode_setattr - Smack check for setting attributes
 * @dentry: the object
 * @iattr: for the force flag
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_setattr(struct dentry *dentry, struct iattr *iattr)
{
        /*
         * Need to allow for clearing the setuid bit.
         */
        if (iattr->ia_valid & ATTR_FORCE)
                return 0;

        return smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE);
}

/**
 * smack_inode_getattr - Smack check for getting attributes
 * @mnt: unused
 * @dentry: the object
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
{
        return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
}

/**
 * smack_inode_setxattr - Smack check for setting xattrs
 * @dentry: the object
 * @name: name of the attribute
 * @value: unused
 * @size: unused
 * @flags: unused
 *
 * This protects the Smack attribute explicitly.
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_setxattr(struct dentry *dentry, const char *name,
                                const void *value, size_t size, int flags)
{
        int rc = 0;

        if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
                if (!capable(CAP_MAC_ADMIN))
                        rc = -EPERM;
        } else
                rc = cap_inode_setxattr(dentry, name, value, size, flags);

        if (rc == 0)
                rc = smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE);

        return rc;
}

/**
 * smack_inode_post_setxattr - Apply the Smack update approved above
 * @dentry: object
 * @name: attribute name
 * @value: attribute value
 * @size: attribute size
 * @flags: unused
 *
 * Set the pointer in the inode blob to the entry found
 * in the master label list.
 */
static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
                                      const void *value, size_t size, int flags)
{
        struct inode_smack *isp;
        char *nsp;

        /*
         * Not SMACK
         */
        if (strcmp(name, XATTR_NAME_SMACK))
                return;

        if (size >= SMK_LABELLEN)
                return;

        isp = dentry->d_inode->i_security;

        /*
         * No locking is done here. This is a pointer
         * assignment.
         */
        nsp = smk_import(value, size);
        if (nsp != NULL)
                isp->smk_inode = nsp;
        else
                isp->smk_inode = smack_known_invalid.smk_known;

        return;
}

/*
 * smack_inode_getxattr - Smack check on getxattr
 * @dentry: the object
 * @name: unused
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_getxattr(struct dentry *dentry, const char *name)
{
        return smk_curacc(smk_of_inode(dentry->d_inode), MAY_READ);
}

/*
 * smack_inode_removexattr - Smack check on removexattr
 * @dentry: the object
 * @name: name of the attribute
 *
 * Removing the Smack attribute requires CAP_MAC_ADMIN
 *
 * Returns 0 if access is permitted, an error code otherwise
 */
static int smack_inode_removexattr(struct dentry *dentry, const char *name)
{
        int rc = 0;

        if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
            strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
                if (!capable(CAP_MAC_ADMIN))
                        rc = -EPERM;
        } else
                rc = cap_inode_removexattr(dentry, name);

        if (rc == 0)
                rc = smk_curacc(smk_of_inode(dentry->d_inode), MAY_WRITE);

        return rc;
}

/**
 * smack_inode_getsecurity - get smack xattrs
 * @inode: the object
 * @name: attribute name
 * @buffer: where to put the result
 * @size: size of the buffer
 * @err: unused
 *
 * Returns the size of the attribute or an error code
 */
static int smack_inode_getsecurity(const struct inode *inode,
                                   const char *name, void **buffer,
                                   bool alloc)
{
        struct socket_smack *ssp;
        struct socket *sock;
        struct super_block *sbp;
        struct inode *ip = (struct inode *)inode;
        char *isp;
        int ilen;
        int rc = 0;

        if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
                isp = smk_of_inode(inode);
                ilen = strlen(isp) + 1;
                *buffer = isp;
                return ilen;
        }

        /*
         * The rest of the Smack xattrs are only on sockets.
         */
        sbp = ip->i_sb;
        if (sbp->s_magic != SOCKFS_MAGIC)
                return -EOPNOTSUPP;

        sock = SOCKET_I(ip);
        if (sock == NULL || sock->sk == NULL)
                return -EOPNOTSUPP;

        ssp = sock->sk->sk_security;

        if (strcmp(name, XATTR_SMACK_IPIN) == 0)
                isp = ssp->smk_in;
        else if (strcmp(name, XATTR_SMACK_IPOUT) == 0)
                isp = ssp->smk_out;
        else
                return -EOPNOTSUPP;

        ilen = strlen(isp) + 1;
        if (rc == 0) {
                *buffer = isp;
                rc = ilen;
        }

        return rc;
}


/**
 * smack_inode_listsecurity - list the Smack attributes
 * @inode: the object
 * @buffer: where they go
 * @buffer_size: size of buffer
 *
 * Returns 0 on success, -EINVAL otherwise
 */
static int smack_inode_listsecurity(struct inode *inode, char *buffer,
                                    size_t buffer_size)
{
        int len = strlen(XATTR_NAME_SMACK);

        if (buffer != NULL && len <= buffer_size) {
                memcpy(buffer, XATTR_NAME_SMACK, len);
                return len;
        }
        return -EINVAL;
}

/**
 * smack_inode_getsecid - Extract inode's security id
 * @inode: inode to extract the info from
 * @secid: where result will be saved
 */
static void smack_inode_getsecid(const struct inode *inode, u32 *secid)
{
        struct inode_smack *isp = inode->i_security;

        *secid = smack_to_secid(isp->smk_inode);
}

/*
 * File Hooks
 */

/**
 * smack_file_permission - Smack check on file operations
 * @file: unused
 * @mask: unused
 *
 * Returns 0
 *
 * Should access checks be done on each read or write?
 * UNICOS and SELinux say yes.
 * Trusted Solaris, Trusted Irix, and just about everyone else says no.
 *
 * I'll say no for now. Smack does not do the frequent
 * label changing that SELinux does.
 */
static int smack_file_permission(struct file *file, int mask)
{
        return 0;
}

/**
 * smack_file_alloc_security - assign a file security blob
 * @file: the object
 *
 * The security blob for a file is a pointer to the master
 * label list, so no allocation is done.
 *
 * Returns 0
 */
static int smack_file_alloc_security(struct file *file)
{
        file->f_security = current_security();
        return 0;
}

/**
 * smack_file_free_security - clear a file security blob
 * @file: the object
 *
 * The security blob for a file is a pointer to the master
 * label list, so no memory is freed.
 */
static void smack_file_free_security(struct file *file)
{
        file->f_security = NULL;
}

/**
 * smack_file_ioctl - Smack check on ioctls
 * @file: the object
 * @cmd: what to do
 * @arg: unused
 *
 * Relies heavily on the correct use of the ioctl command conventions.
 *
 * Returns 0 if allowed, error code otherwise
 */
static int smack_file_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
        int rc = 0;

        if (_IOC_DIR(cmd) & _IOC_WRITE)
                rc = smk_curacc(file->f_security, MAY_WRITE);

        if (rc == 0 && (_IOC_DIR(cmd) & _IOC_READ))
                rc = smk_curacc(file->f_security, MAY_READ);

        return rc;
}

/**
 * smack_file_lock - Smack check on file locking
 * @file: the object
 * @cmd unused
 *
 * Returns 0 if current has write access, error code otherwise
 */
static int smack_file_lock(struct file *file, unsigned int cmd)
{
        return smk_curacc(file->f_security, MAY_WRITE);
}

/**
 * smack_file_fcntl - Smack check on fcntl
 * @file: the object
 * @cmd: what action to check
 * @arg: unused
 *
 * Returns 0 if current has access, error code otherwise
 */
static int smack_file_fcntl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
        int rc;

        switch (cmd) {
        case F_DUPFD:
        case F_GETFD:
        case F_GETFL:
        case F_GETLK:
        case F_GETOWN:
        case F_GETSIG:
                rc = smk_curacc(file->f_security, MAY_READ);
                break;
        case F_SETFD:
        case F_SETFL:
        case F_SETLK:
        case F_SETLKW:
        case F_SETOWN:
        case F_SETSIG:
                rc = smk_curacc(file->f_security, MAY_WRITE);
                break;
        default:
                rc = smk_curacc(file->f_security, MAY_READWRITE);
        }

        return rc;
}

/**
 * smack_file_set_fowner - set the file security blob value
 * @file: object in question
 *
 * Returns 0
 * Further research may be required on this one.
 */
static int smack_file_set_fowner(struct file *file)
{
        file->f_security = current_security();
        return 0;
}

/**
 * smack_file_send_sigiotask - Smack on sigio
 * @tsk: The target task
 * @fown: the object the signal come from
 * @signum: unused
 *
 * Allow a privileged task to get signals even if it shouldn't
 *
 * Returns 0 if a subject with the object's smack could
 * write to the task, an error code otherwise.
 */
static int smack_file_send_sigiotask(struct task_struct *tsk,
                                     struct fown_struct *fown, int signum)
{
        struct file *file;
        int rc;

        /*
         * struct fown_struct is never outside the context of a struct file
         */
        file = container_of(fown, struct file, f_owner);
        rc = smk_access(file->f_security, tsk->cred->security, MAY_WRITE);
        if (rc != 0 && has_capability(tsk, CAP_MAC_OVERRIDE))
                return 0;
        return rc;
}

/**
 * smack_file_receive - Smack file receive check
 * @file: the object
 *
 * Returns 0 if current has access, error code otherwise
 */
static int smack_file_receive(struct file *file)
{
        int may = 0;

        /*
         * This code relies on bitmasks.
         */
        if (file->f_mode & FMODE_READ)
                may = MAY_READ;
        if (file->f_mode & FMODE_WRITE)
                may |= MAY_WRITE;

        return smk_curacc(file->f_security, may);
}

/*
 * Task hooks
 */

/**
 * smack_cred_alloc_security - "allocate" a task cred blob
 * @cred: the task creds in need of a blob
 *
 * Smack isn't using copies of blobs. Everyone
 * points to an immutable list. No alloc required.
 * No data copy required.
 *
 * Always returns 0
 */
static int smack_cred_alloc_security(struct cred *cred)
{
        cred->security = current_security();
        return 0;
}

/**
 * smack_cred_free - "free" task-level security credentials
 * @cred: the credentials in question
 *
 * Smack isn't using copies of blobs. Everyone
 * points to an immutable list. The blobs never go away.
 * There is no leak here.
 */
static void smack_cred_free(struct cred *cred)
{
        cred->security = NULL;
}

/**
 * smack_task_setpgid - Smack check on setting pgid
 * @p: the task object
 * @pgid: unused
 *
 * Return 0 if write access is permitted
 */
static int smack_task_setpgid(struct task_struct *p, pid_t pgid)
{
        return smk_curacc(task_security(p), MAY_WRITE);
}

/**
 * smack_task_getpgid - Smack access check for getpgid
 * @p: the object task
 *
 * Returns 0 if current can read the object task, error code otherwise
 */
static int smack_task_getpgid(struct task_struct *p)
{
        return smk_curacc(task_security(p), MAY_READ);
}

/**
 * smack_task_getsid - Smack access check for getsid
 * @p: the object task
 *
 * Returns 0 if current can read the object task, error code otherwise
 */
static int smack_task_getsid(struct task_struct *p)
{
        return smk_curacc(task_security(p), MAY_READ);
}

/**
 * smack_task_getsecid - get the secid of the task
 * @p: the object task
 * @secid: where to put the result
 *
 * Sets the secid to contain a u32 version of the smack label.
 */
static void smack_task_getsecid(struct task_struct *p, u32 *secid)
{
        *secid = smack_to_secid(task_security(p));
}

/**
 * smack_task_setnice - Smack check on setting nice
 * @p: the task object
 * @nice: unused
 *
 * Return 0 if write access is permitted
 */
static int smack_task_setnice(struct task_struct *p, int nice)
{
        int rc;

        rc = cap_task_setnice(p, nice);
        if (rc == 0)
                rc = smk_curacc(task_security(p), MAY_WRITE);
        return rc;
}

/**
 * smack_task_setioprio - Smack check on setting ioprio
 * @p: the task object
 * @ioprio: unused
 *
 * Return 0 if write access is permitted
 */
static int smack_task_setioprio(struct task_struct *p, int ioprio)
{
        int rc;

        rc = cap_task_setioprio(p, ioprio);
        if (rc == 0)
                rc = smk_curacc(task_security(p), MAY_WRITE);
        return rc;
}

/**
 * smack_task_getioprio - Smack check on reading ioprio
 * @p: the task object
 *
 * Return 0 if read access is permitted
 */
static int smack_task_getioprio(struct task_struct *p)
{
        return smk_curacc(task_security(p), MAY_READ);
}

/**
 * smack_task_setscheduler - Smack check on setting scheduler
 * @p: the task object
 * @policy: unused
 * @lp: unused
 *
 * Return 0 if read access is permitted
 */
static int smack_task_setscheduler(struct task_struct *p, int policy,
                                   struct sched_param *lp)
{
        int rc;

        rc = cap_task_setscheduler(p, policy, lp);
        if (rc == 0)
                rc = smk_curacc(task_security(p), MAY_WRITE);
        return rc;
}

/**
 * smack_task_getscheduler - Smack check on reading scheduler
 * @p: the task object
 *
 * Return 0 if read access is permitted
 */
static int smack_task_getscheduler(struct task_struct *p)
{
        return smk_curacc(task_security(p), MAY_READ);
}

/**
 * smack_task_movememory - Smack check on moving memory
 * @p: the task object
 *
 * Return 0 if write access is permitted
 */
static int smack_task_movememory(struct task_struct *p)
{
        return smk_curacc(task_security(p), MAY_WRITE);
}

/**
 * smack_task_kill - Smack check on signal delivery
 * @p: the task object
 * @info: unused
 * @sig: unused
 * @secid: identifies the smack to use in lieu of current's
 *
 * Return 0 if write access is permitted
 *
 * The secid behavior is an artifact of an SELinux hack
 * in the USB code. Someday it may go away.
 */
static int smack_task_kill(struct task_struct *p, struct siginfo *info,
                           int sig, u32 secid)
{
        /*
         * Sending a signal requires that the sender
         * can write the receiver.
         */
        if (secid == 0)
                return smk_curacc(task_security(p), MAY_WRITE);
        /*
         * If the secid isn't 0 we're dealing with some USB IO
         * specific behavior. This is not clean. For one thing
         * we can't take privilege into account.
         */
        return smk_access(smack_from_secid(secid), task_security(p), MAY_WRITE);
}

/**
 * smack_task_wait - Smack access check for waiting
 * @p: task to wait for
 *
 * Returns 0 if current can wait for p, error code otherwise
 */
static int smack_task_wait(struct task_struct *p)
{
        int rc;

        rc = smk_access(current_security(), task_security(p), MAY_WRITE);
        if (rc == 0)
                return 0;

        /*
         * Allow the operation to succeed if either task
         * has privilege to perform operations that might
         * account for the smack labels having gotten to
         * be different in the first place.
         *
         * This breaks the strict subject/object access
         * control ideal, taking the object's privilege
         * state into account in the decision as well as
         * the smack value.
         */
        if (capable(CAP_MAC_OVERRIDE) || has_capability(p, CAP_MAC_OVERRIDE))
                return 0;

        return rc;
}

/**
 * smack_task_to_inode - copy task smack into the inode blob
 * @p: task to copy from
 * inode: inode to copy to
 *
 * Sets the smack pointer in the inode security blob
 */
static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
{
        struct inode_smack *isp = inode->i_security;
        isp->smk_inode = task_security(p);
}

/*
 * Socket hooks.
 */

/**
 * smack_sk_alloc_security - Allocate a socket blob
 * @sk: the socket
 * @family: unused
 * @priority: memory allocation priority
 *
 * Assign Smack pointers to current
 *
 * Returns 0 on success, -ENOMEM is there's no memory
 */
static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags)
{
        char *csp = current_security();
        struct socket_smack *ssp;

        ssp = kzalloc(sizeof(struct socket_smack), gfp_flags);
        if (ssp == NULL)
                return -ENOMEM;

        ssp->smk_in = csp;
        ssp->smk_out = csp;
        ssp->smk_packet[0] = '\0';

        sk->sk_security = ssp;

        return 0;
}

/**
 * smack_sk_free_security - Free a socket blob
 * @sk: the socket
 *
 * Clears the blob pointer
 */
static void smack_sk_free_security(struct sock *sk)
{
        kfree(sk->sk_security);
}

/**
 * smack_set_catset - convert a capset to netlabel mls categories
 * @catset: the Smack categories
 * @sap: where to put the netlabel categories
 *
 * Allocates and fills attr.mls.cat
 */
static void smack_set_catset(char *catset, struct netlbl_lsm_secattr *sap)
{
        unsigned char *cp;
        unsigned char m;
        int cat;
        int rc;
        int byte;

        if (!catset)
                return;

        sap->flags |= NETLBL_SECATTR_MLS_CAT;
        sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
        sap->attr.mls.cat->startbit = 0;

        for (cat = 1, cp = catset, byte = 0; byte < SMK_LABELLEN; cp++, byte++)
                for (m = 0x80; m != 0; m >>= 1, cat++) {
                        if ((m & *cp) == 0)
                                continue;
                        rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat,
                                                          cat, GFP_ATOMIC);
                }
}

/**
 * smack_to_secattr - fill a secattr from a smack value
 * @smack: the smack value
 * @nlsp: where the result goes
 *
 * Casey says that CIPSO is good enough for now.
 * It can be used to effect.
 * It can also be abused to effect when necessary.
 * Appologies to the TSIG group in general and GW in particular.
 */
static void smack_to_secattr(char *smack, struct netlbl_lsm_secattr *nlsp)
{
        struct smack_cipso cipso;
        int rc;

        switch (smack_net_nltype) {
        case NETLBL_NLTYPE_CIPSOV4:
                nlsp->domain = smack;
                nlsp->flags = NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;

                rc = smack_to_cipso(smack, &cipso);
                if (rc == 0) {
                        nlsp->attr.mls.lvl = cipso.smk_level;
                        smack_set_catset(cipso.smk_catset, nlsp);
                } else {
                        nlsp->attr.mls.lvl = smack_cipso_direct;
                        smack_set_catset(smack, nlsp);
                }
                break;
        default:
                break;
        }
}

/**
 * smack_netlabel - Set the secattr on a socket
 * @sk: the socket
 *
 * Convert the outbound smack value (smk_out) to a
 * secattr and attach it to the socket.
 *
 * Returns 0 on success or an error code
 */
static int smack_netlabel(struct sock *sk)
{
        struct socket_smack *ssp;
        struct netlbl_lsm_secattr secattr;
        int rc;

        ssp = sk->sk_security;
        netlbl_secattr_init(&secattr);
        smack_to_secattr(ssp->smk_out, &secattr);
        rc = netlbl_sock_setattr(sk, &secattr);
        netlbl_secattr_destroy(&secattr);

        return rc;
}

/**
 * smack_inode_setsecurity - set smack xattrs
 * @inode: the object
 * @name: attribute name
 * @value: attribute value
 * @size: size of the attribute
 * @flags: unused
 *
 * Sets the named attribute in the appropriate blob
 *
 * Returns 0 on success, or an error code
 */
static int smack_inode_setsecurity(struct inode *inode, const char *name,
                                   const void *value, size_t size, int flags)
{
        char *sp;
        struct inode_smack *nsp = inode->i_security;
        struct socket_smack *ssp;
        struct socket *sock;
        int rc = 0;

        if (value == NULL || size > SMK_LABELLEN)
                return -EACCES;

        sp = smk_import(value, size);
        if (sp == NULL)
                return -EINVAL;

        if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
                nsp->smk_inode = sp;
                return 0;
        }
        /*
         * The rest of the Smack xattrs are only on sockets.
         */
        if (inode->i_sb->s_magic != SOCKFS_MAGIC)
                return -EOPNOTSUPP;

        sock = SOCKET_I(inode);
        if (sock == NULL || sock->sk == NULL)
                return -EOPNOTSUPP;

        ssp = sock->sk->sk_security;

        if (strcmp(name, XATTR_SMACK_IPIN) == 0)
                ssp->smk_in = sp;
        else if (strcmp(name, XATTR_SMACK_IPOUT) == 0) {
                ssp->smk_out = sp;
                rc = smack_netlabel(sock->sk);
                if (rc != 0)
                        printk(KERN_WARNING "Smack: \"%s\" netlbl error %d.\n",
                               __func__, -rc);
        } else
                return -EOPNOTSUPP;

        return 0;
}

/**
 * smack_socket_post_create - finish socket setup
 * @sock: the socket
 * @family: protocol family
 * @type: unused
 * @protocol: unused
 * @kern: unused
 *
 * Sets the netlabel information on the socket
 *
 * Returns 0 on success, and error code otherwise
 */
static int smack_socket_post_create(struct socket *sock, int family,
                                    int type, int protocol, int kern)
{
        if (family != PF_INET || sock->sk == NULL)
                return 0;
        /*
         * Set the outbound netlbl.
         */
        return smack_netlabel(sock->sk);
}

/**
 * smack_flags_to_may - convert S_ to MAY_ values
 * @flags: the S_ value
 *
 * Returns the equivalent MAY_ value
 */
static int smack_flags_to_may(int flags)
{
        int may = 0;

        if (flags & S_IRUGO)
                may |= MAY_READ;
        if (flags & S_IWUGO)
                may |= MAY_WRITE;
        if (flags & S_IXUGO)
                may |= MAY_EXEC;

        return may;
}

/**
 * smack_msg_msg_alloc_security - Set the security blob for msg_msg
 * @msg: the object
 *
 * Returns 0
 */
static int smack_msg_msg_alloc_security(struct msg_msg *msg)
{
        msg->security = current_security();
        return 0;
}

/**
 * smack_msg_msg_free_security - Clear the security blob for msg_msg
 * @msg: the object
 *
 * Clears the blob pointer
 */
static void smack_msg_msg_free_security(struct msg_msg *msg)
{
        msg->security = NULL;
}

/**
 * smack_of_shm - the smack pointer for the shm
 * @shp: the object
 *
 * Returns a pointer to the smack value
 */
static char *smack_of_shm(struct shmid_kernel *shp)
{
        return (char *)shp->shm_perm.security;
}

/**
 * smack_shm_alloc_security - Set the security blob for shm
 * @shp: the object
 *
 * Returns 0
 */
static int smack_shm_alloc_security(struct shmid_kernel *shp)
{
        struct kern_ipc_perm *isp = &shp->shm_perm;

        isp->security = current_security();
        return 0;
}

/**
 * smack_shm_free_security - Clear the security blob for shm
 * @shp: the object
 *
 * Clears the blob pointer
 */
static void smack_shm_free_security(struct shmid_kernel *shp)
{
        struct kern_ipc_perm *isp = &shp->shm_perm;

        isp->security = NULL;
}

/**
 * smack_shm_associate - Smack access check for shm
 * @shp: the object
 * @shmflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_shm_associate(struct shmid_kernel *shp, int shmflg)
{
        char *ssp = smack_of_shm(shp);
        int may;

        may = smack_flags_to_may(shmflg);
        return smk_curacc(ssp, may);
}

/**
 * smack_shm_shmctl - Smack access check for shm
 * @shp: the object
 * @cmd: what it wants to do
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_shm_shmctl(struct shmid_kernel *shp, int cmd)
{
        char *ssp;
        int may;

        switch (cmd) {
        case IPC_STAT:
        case SHM_STAT:
                may = MAY_READ;
                break;
        case IPC_SET:
        case SHM_LOCK:
        case SHM_UNLOCK:
        case IPC_RMID:
                may = MAY_READWRITE;
                break;
        case IPC_INFO:
        case SHM_INFO:
                /*
                 * System level information.
                 */
                return 0;
        default:
                return -EINVAL;
        }

        ssp = smack_of_shm(shp);
        return smk_curacc(ssp, may);
}

/**
 * smack_shm_shmat - Smack access for shmat
 * @shp: the object
 * @shmaddr: unused
 * @shmflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_shm_shmat(struct shmid_kernel *shp, char __user *shmaddr,
                           int shmflg)
{
        char *ssp = smack_of_shm(shp);
        int may;

        may = smack_flags_to_may(shmflg);
        return smk_curacc(ssp, may);
}

/**
 * smack_of_sem - the smack pointer for the sem
 * @sma: the object
 *
 * Returns a pointer to the smack value
 */
static char *smack_of_sem(struct sem_array *sma)
{
        return (char *)sma->sem_perm.security;
}

/**
 * smack_sem_alloc_security - Set the security blob for sem
 * @sma: the object
 *
 * Returns 0
 */
static int smack_sem_alloc_security(struct sem_array *sma)
{
        struct kern_ipc_perm *isp = &sma->sem_perm;

        isp->security = current_security();
        return 0;
}

/**
 * smack_sem_free_security - Clear the security blob for sem
 * @sma: the object
 *
 * Clears the blob pointer
 */
static void smack_sem_free_security(struct sem_array *sma)
{
        struct kern_ipc_perm *isp = &sma->sem_perm;

        isp->security = NULL;
}

/**
 * smack_sem_associate - Smack access check for sem
 * @sma: the object
 * @semflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_sem_associate(struct sem_array *sma, int semflg)
{
        char *ssp = smack_of_sem(sma);
        int may;

        may = smack_flags_to_may(semflg);
        return smk_curacc(ssp, may);
}

/**
 * smack_sem_shmctl - Smack access check for sem
 * @sma: the object
 * @cmd: what it wants to do
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_sem_semctl(struct sem_array *sma, int cmd)
{
        char *ssp;
        int may;

        switch (cmd) {
        case GETPID:
        case GETNCNT:
        case GETZCNT:
        case GETVAL:
        case GETALL:
        case IPC_STAT:
        case SEM_STAT:
                may = MAY_READ;
                break;
        case SETVAL:
        case SETALL:
        case IPC_RMID:
        case IPC_SET:
                may = MAY_READWRITE;
                break;
        case IPC_INFO:
        case SEM_INFO:
                /*
                 * System level information
                 */
                return 0;
        default:
                return -EINVAL;
        }

        ssp = smack_of_sem(sma);
        return smk_curacc(ssp, may);
}

/**
 * smack_sem_semop - Smack checks of semaphore operations
 * @sma: the object
 * @sops: unused
 * @nsops: unused
 * @alter: unused
 *
 * Treated as read and write in all cases.
 *
 * Returns 0 if access is allowed, error code otherwise
 */
static int smack_sem_semop(struct sem_array *sma, struct sembuf *sops,
                           unsigned nsops, int alter)
{
        char *ssp = smack_of_sem(sma);

        return smk_curacc(ssp, MAY_READWRITE);
}

/**
 * smack_msg_alloc_security - Set the security blob for msg
 * @msq: the object
 *
 * Returns 0
 */
static int smack_msg_queue_alloc_security(struct msg_queue *msq)
{
        struct kern_ipc_perm *kisp = &msq->q_perm;

        kisp->security = current_security();
        return 0;
}

/**
 * smack_msg_free_security - Clear the security blob for msg
 * @msq: the object
 *
 * Clears the blob pointer
 */
static void smack_msg_queue_free_security(struct msg_queue *msq)
{
        struct kern_ipc_perm *kisp = &msq->q_perm;

        kisp->security = NULL;
}

/**
 * smack_of_msq - the smack pointer for the msq
 * @msq: the object
 *
 * Returns a pointer to the smack value
 */
static char *smack_of_msq(struct msg_queue *msq)
{
        return (char *)msq->q_perm.security;
}

/**
 * smack_msg_queue_associate - Smack access check for msg_queue
 * @msq: the object
 * @msqflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_msg_queue_associate(struct msg_queue *msq, int msqflg)
{
        char *msp = smack_of_msq(msq);
        int may;

        may = smack_flags_to_may(msqflg);
        return smk_curacc(msp, may);
}

/**
 * smack_msg_queue_msgctl - Smack access check for msg_queue
 * @msq: the object
 * @cmd: what it wants to do
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_msg_queue_msgctl(struct msg_queue *msq, int cmd)
{
        char *msp;
        int may;

        switch (cmd) {
        case IPC_STAT:
        case MSG_STAT:
                may = MAY_READ;
                break;
        case IPC_SET:
        case IPC_RMID:
                may = MAY_READWRITE;
                break;
        case IPC_INFO:
        case MSG_INFO:
                /*
                 * System level information
                 */
                return 0;
        default:
                return -EINVAL;
        }

        msp = smack_of_msq(msq);
        return smk_curacc(msp, may);
}

/**
 * smack_msg_queue_msgsnd - Smack access check for msg_queue
 * @msq: the object
 * @msg: unused
 * @msqflg: access requested
 *
 * Returns 0 if current has the requested access, error code otherwise
 */
static int smack_msg_queue_msgsnd(struct msg_queue *msq, struct msg_msg *msg,
                                  int msqflg)
{
        char *msp = smack_of_msq(msq);
        int rc;

        rc = smack_flags_to_may(msqflg);
        return smk_curacc(msp, rc);
}

/**
 * smack_msg_queue_msgsnd - Smack access check for msg_queue
 * @msq: the object
 * @msg: unused
 * @target: unused
 * @type: unused
 * @mode: unused
 *
 * Returns 0 if current has read and write access, error code otherwise
 */
static int smack_msg_queue_msgrcv(struct msg_queue *msq, struct msg_msg *msg,
                        struct task_struct *target, long type, int mode)
{
        char *msp = smack_of_msq(msq);

        return smk_curacc(msp, MAY_READWRITE);
}

/**
 * smack_ipc_permission - Smack access for ipc_permission()
 * @ipp: the object permissions
 * @flag: access requested
 *
 * Returns 0 if current has read and write access, error code otherwise
 */
static int smack_ipc_permission(struct kern_ipc_perm *ipp, short flag)
{
        char *isp = ipp->security;
        int may;

        may = smack_flags_to_may(flag);
        return smk_curacc(isp, may);
}

/**
 * smack_ipc_getsecid - Extract smack security id
 * @ipcp: the object permissions
 * @secid: where result will be saved
 */
static void smack_ipc_getsecid(struct kern_ipc_perm *ipp, u32 *secid)
{
        char *smack = ipp->security;

        *secid = smack_to_secid(smack);
}

/**
 * smack_d_instantiate - Make sure the blob is correct on an inode
 * @opt_dentry: unused
 * @inode: the object
 *
 * Set the inode's security blob if it hasn't been done already.
 */
static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
{
        struct super_block *sbp;
        struct superblock_smack *sbsp;
        struct inode_smack *isp;
        char *csp = current_security();
        char *fetched;
        char *final;
        struct dentry *dp;

        if (inode == NULL)
                return;

        isp = inode->i_security;

        mutex_lock(&isp->smk_lock);
        /*
         * If the inode is already instantiated
         * take the quick way out
         */
        if (isp->smk_flags & SMK_INODE_INSTANT)
                goto unlockandout;

        sbp = inode->i_sb;
        sbsp = sbp->s_security;
        /*
         * We're going to use the superblock default label
         * if there's no label on the file.
         */
        final = sbsp->smk_default;

        /*
         * If this is the root inode the superblock
         * may be in the process of initialization.
         * If that is the case use the root value out
         * of the superblock.
         */
        if (opt_dentry->d_parent == opt_dentry) {
                isp->smk_inode = sbsp->smk_root;
                isp->smk_flags |= SMK_INODE_INSTANT;
                goto unlockandout;
        }

        /*
         * This is pretty hackish.
         * Casey says that we shouldn't have to do
         * file system specific code, but it does help
         * with keeping it simple.
         */
        switch (sbp->s_magic) {
        case SMACK_MAGIC:
                /*
                 * Casey says that it's a little embarassing
                 * that the smack file system doesn't do
                 * extended attributes.
                 */
                final = smack_known_star.smk_known;
                break;
        case PIPEFS_MAGIC:
                /*
                 * Casey says pipes are easy (?)
                 */
                final = smack_known_star.smk_known;
                break;
        case DEVPTS_SUPER_MAGIC:
                /*
                 * devpts seems content with the label of the task.
                 * Programs that change smack have to treat the
                 * pty with respect.
                 */
                final = csp;
                break;
        case SOCKFS_MAGIC:
                /*
                 * Casey says sockets get the smack of the task.
                 */
                final = csp;
                break;
        case PROC_SUPER_MAGIC:
                /*
                 * Casey says procfs appears not to care.
                 * The superblock default suffices.
                 */
                break;
        case TMPFS_MAGIC:
                /*
                 * Device labels should come from the filesystem,
                 * but watch out, because they're volitile,
                 * getting recreated on every reboot.
                 */
                final = smack_known_star.smk_known;
                /*
                 * No break.
                 *
                 * If a smack value has been set we want to use it,
                 * but since tmpfs isn't giving us the opportunity
                 * to set mount options simulate setting the
                 * superblock default.
                 */
        default:
                /*
                 * This isn't an understood special case.
                 * Get the value from the xattr.
                 *
                 * No xattr support means, alas, no SMACK label.
                 * Use the aforeapplied default.
                 * It would be curious if the label of the task
                 * does not match that assigned.
                 */
                if (inode->i_op->getxattr == NULL)
                        break;
                /*
                 * Get the dentry for xattr.
                 */
                if (opt_dentry == NULL) {
                        dp = d_find_alias(inode);
                        if (dp == NULL)
                                break;
                } else {
                        dp = dget(opt_dentry);
                        if (dp == NULL)
                                break;
                }

                fetched = smk_fetch(inode, dp);
                if (fetched != NULL)
                        final = fetched;

                dput(dp);
                break;
        }

        if (final == NULL)
                isp->smk_inode = csp;
        else
                isp->smk_inode = final;

        isp->smk_flags |= SMK_INODE_INSTANT;

unlockandout:
        mutex_unlock(&isp->smk_lock);
        return;
}

/**
 * smack_getprocattr - Smack process attribute access
 * @p: the object task
 * @name: the name of the attribute in /proc/.../attr
 * @value: where to put the result
 *
 * Places a copy of the task Smack into value
 *
 * Returns the length of the smack label or an error code
 */
static int smack_getprocattr(struct task_struct *p, char *name, char **value)
{
        char *cp;
        int slen;

        if (strcmp(name, "current") != 0)
                return -EINVAL;

        cp = kstrdup(task_security(p), GFP_KERNEL);
        if (cp == NULL)
                return -ENOMEM;

        slen = strlen(cp);
        *value = cp;
        return slen;
}

/**
 * smack_setprocattr - Smack process attribute setting
 * @p: the object task
 * @name: the name of the attribute in /proc/.../attr
 * @value: the value to set
 * @size: the size of the value
 *
 * Sets the Smack value of the task. Only setting self
 * is permitted and only with privilege
 *
 * Returns the length of the smack label or an error code
 */
static int smack_setprocattr(struct task_struct *p, char *name,
                             void *value, size_t size)
{
        char *newsmack;

        /*
         * Changing another process' Smack value is too dangerous
         * and supports no sane use case.
         */
        if (p != current)
                return -EPERM;

        if (!capable(CAP_MAC_ADMIN))
                return -EPERM;

        if (value == NULL || size == 0 || size >= SMK_LABELLEN)
                return -EINVAL;

        if (strcmp(name, "current") != 0)
                return -EINVAL;

        newsmack = smk_import(value, size);
        if (newsmack == NULL)
                return -EINVAL;

        p->cred->security = newsmack;
        return size;
}

/**
 * smack_unix_stream_connect - Smack access on UDS
 * @sock: one socket
 * @other: the other socket
 * @newsk: unused
 *
 * Return 0 if a subject with the smack of sock could access
 * an object with the smack of other, otherwise an error code
 */
static int smack_unix_stream_connect(struct socket *sock,
                                     struct socket *other, struct sock *newsk)
{
        struct inode *sp = SOCK_INODE(sock);
        struct inode *op = SOCK_INODE(other);

        return smk_access(smk_of_inode(sp), smk_of_inode(op), MAY_READWRITE);
}

/**
 * smack_unix_may_send - Smack access on UDS
 * @sock: one socket
 * @other: the other socket
 *
 * Return 0 if a subject with the smack of sock could access
 * an object with the smack of other, otherwise an error code
 */
static int smack_unix_may_send(struct socket *sock, struct socket *other)
{
        struct inode *sp = SOCK_INODE(sock);
        struct inode *op = SOCK_INODE(other);

        return smk_access(smk_of_inode(sp), smk_of_inode(op), MAY_WRITE);
}

/**
 * smack_from_secattr - Convert a netlabel attr.mls.lvl/attr.mls.cat
 *      pair to smack
 * @sap: netlabel secattr
 * @sip: where to put the result
 *
 * Copies a smack label into sip
 */
static void smack_from_secattr(struct netlbl_lsm_secattr *sap, char *sip)
{
        char smack[SMK_LABELLEN];
        int pcat;

        if ((sap->flags & NETLBL_SECATTR_MLS_LVL) == 0) {
                /*
                 * If there are flags but no level netlabel isn't
                 * behaving the way we expect it to.
                 *
                 * Without guidance regarding the smack value
                 * for the packet fall back on the network
                 * ambient value.
                 */
                strncpy(sip, smack_net_ambient, SMK_MAXLEN);
                return;
        }
        /*
         * Get the categories, if any
         */
        memset(smack, '\0', SMK_LABELLEN);
        if ((sap->flags & NETLBL_SECATTR_MLS_CAT) != 0)
                for (pcat = -1;;) {
                        pcat = netlbl_secattr_catmap_walk(sap->attr.mls.cat,
                                                          pcat + 1);
                        if (pcat < 0)
                                break;
                        smack_catset_bit(pcat, smack);
                }
        /*
         * If it is CIPSO using smack direct mapping
         * we are already done. WeeHee.
         */
        if (sap->attr.mls.lvl == smack_cipso_direct) {
                memcpy(sip, smack, SMK_MAXLEN);
                return;
        }
        /*
         * Look it up in the supplied table if it is not a direct mapping.
         */
        smack_from_cipso(sap->attr.mls.lvl, smack, sip);
        return;
}

/**
 * smack_socket_sock_rcv_skb - Smack packet delivery access check
 * @sk: socket
 * @skb: packet
 *
 * Returns 0 if the packet should be delivered, an error code otherwise
 */
static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
{
        struct netlbl_lsm_secattr secattr;
        struct socket_smack *ssp = sk->sk_security;
        char smack[SMK_LABELLEN];
        int rc;

        if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
                return 0;

        /*
         * Translate what netlabel gave us.
         */
        memset(smack, '\0', SMK_LABELLEN);
        netlbl_secattr_init(&secattr);
        rc = netlbl_skbuff_getattr(skb, sk->sk_family, &secattr);
        if (rc == 0)
                smack_from_secattr(&secattr, smack);
        else
                strncpy(smack, smack_net_ambient, SMK_MAXLEN);
        netlbl_secattr_destroy(&secattr);
        /*
         * Receiving a packet requires that the other end
         * be able to write here. Read access is not required.
         * This is the simplist possible security model
         * for networking.
         */
        rc = smk_access(smack, ssp->smk_in, MAY_WRITE);
        if (rc != 0)
                netlbl_skbuff_err(skb, rc, 0);
        return rc;
}

/**
 * smack_socket_getpeersec_stream - pull in packet label
 * @sock: the socket
 * @optval: user's destination
 * @optlen: size thereof
 * @len: max thereoe
 *
 * returns zero on success, an error code otherwise
 */
static int smack_socket_getpeersec_stream(struct socket *sock,
                                          char __user *optval,
                                          int __user *optlen, unsigned len)
{
        struct socket_smack *ssp;
        int slen;
        int rc = 0;

        ssp = sock->sk->sk_security;
        slen = strlen(ssp->smk_packet) + 1;

        if (slen > len)
                rc = -ERANGE;
        else if (copy_to_user(optval, ssp->smk_packet, slen) != 0)
                rc = -EFAULT;

        if (put_user(slen, optlen) != 0)
                rc = -EFAULT;

        return rc;
}


/**
 * smack_socket_getpeersec_dgram - pull in packet label
 * @sock: the socket
 * @skb: packet data
 * @secid: pointer to where to put the secid of the packet
 *
 * Sets the netlabel socket state on sk from parent
 */
static int smack_socket_getpeersec_dgram(struct socket *sock,
                                         struct sk_buff *skb, u32 *secid)

{
        struct netlbl_lsm_secattr secattr;
        struct sock *sk;
        char smack[SMK_LABELLEN];
        int family = PF_INET;
        u32 s;
        int rc;

        /*
         * Only works for families with packets.
         */
        if (sock != NULL) {
                sk = sock->sk;
                if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
                        return 0;
                family = sk->sk_family;
        }
        /*
         * Translate what netlabel gave us.
         */
        memset(smack, '\0', SMK_LABELLEN);
        netlbl_secattr_init(&secattr);
        rc = netlbl_skbuff_getattr(skb, family, &secattr);
        if (rc == 0)
                smack_from_secattr(&secattr, smack);
        netlbl_secattr_destroy(&secattr);

        /*
         * Give up if we couldn't get anything
         */
        if (rc != 0)
                return rc;

        s = smack_to_secid(smack);
        if (s == 0)
                return -EINVAL;

        *secid = s;
        return 0;
}

/**
 * smack_sock_graft - graft access state between two sockets
 * @sk: fresh sock
 * @parent: donor socket
 *
 * Sets the netlabel socket state on sk from parent
 */
static void smack_sock_graft(struct sock *sk, struct socket *parent)
{
        struct socket_smack *ssp;
        int rc;

        if (sk == NULL)
                return;

        if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
                return;

        ssp = sk->sk_security;
        ssp->smk_in = ssp->smk_out = current_security();
        ssp->smk_packet[0] = '\0';

        rc = smack_netlabel(sk);
        if (rc != 0)
                printk(KERN_WARNING "Smack: \"%s\" netlbl error %d.\n",
                       __func__, -rc);
}

/**
 * smack_inet_conn_request - Smack access check on connect
 * @sk: socket involved
 * @skb: packet
 * @req: unused
 *
 * Returns 0 if a task with the packet label could write to
 * the socket, otherwise an error code
 */
static int smack_inet_conn_request(struct sock *sk, struct sk_buff *skb,
                                   struct request_sock *req)
{
        struct netlbl_lsm_secattr skb_secattr;
        struct socket_smack *ssp = sk->sk_security;
        char smack[SMK_LABELLEN];
        int rc;

        if (skb == NULL)
                return -EACCES;

        memset(smack, '\0', SMK_LABELLEN);
        netlbl_secattr_init(&skb_secattr);
        rc = netlbl_skbuff_getattr(skb, sk->sk_family, &skb_secattr);
        if (rc == 0)
                smack_from_secattr(&skb_secattr, smack);
        else
                strncpy(smack, smack_known_huh.smk_known, SMK_MAXLEN);
        netlbl_secattr_destroy(&skb_secattr);
        /*
         * Receiving a packet requires that the other end
         * be able to write here. Read access is not required.
         *
         * If the request is successful save the peer's label
         * so that SO_PEERCRED can report it.
         */
        rc = smk_access(smack, ssp->smk_in, MAY_WRITE);
        if (rc == 0)
                strncpy(ssp->smk_packet, smack, SMK_MAXLEN);

        return rc;
}

/*
 * Key management security hooks
 *
 * Casey has not tested key support very heavily.
 * The permission check is most likely too restrictive.
 * If you care about keys please have a look.
 */
#ifdef CONFIG_KEYS

/**
 * smack_key_alloc - Set the key security blob
 * @key: object
 * @tsk: the task associated with the key
 * @flags: unused
 *
 * No allocation required
 *
 * Returns 0
 */
static int smack_key_alloc(struct key *key, struct task_struct *tsk,
                           unsigned long flags)
{
        key->security = tsk->cred->security;
        return 0;
}

/**
 * smack_key_free - Clear the key security blob
 * @key: the object
 *
 * Clear the blob pointer
 */
static void smack_key_free(struct key *key)
{
        key->security = NULL;
}

/*
 * smack_key_permission - Smack access on a key
 * @key_ref: gets to the object
 * @context: task involved
 * @perm: unused
 *
 * Return 0 if the task has read and write to the object,
 * an error code otherwise
 */
static int smack_key_permission(key_ref_t key_ref,
                                struct task_struct *context, key_perm_t perm)
{
        struct key *keyp;

        keyp = key_ref_to_ptr(key_ref);
        if (keyp == NULL)
                return -EINVAL;
        /*
         * If the key hasn't been initialized give it access so that
         * it may do so.
         */
        if (keyp->security == NULL)
                return 0;
        /*
         * This should not occur
         */
        if (context->cred->security == NULL)
                return -EACCES;

        return smk_access(context->cred->security, keyp->security,
                          MAY_READWRITE);
}
#endif /* CONFIG_KEYS */

/*
 * Smack Audit hooks
 *
 * Audit requires a unique representation of each Smack specific
 * rule. This unique representation is used to distinguish the
 * object to be audited from remaining kernel objects and also
 * works as a glue between the audit hooks.
 *
 * Since repository entries are added but never deleted, we'll use
 * the smack_known label address related to the given audit rule as
 * the needed unique representation. This also better fits the smack
 * model where nearly everything is a label.
 */
#ifdef CONFIG_AUDIT

/**
 * smack_audit_rule_init - Initialize a smack audit rule
 * @field: audit rule fields given from user-space (audit.h)
 * @op: required testing operator (=, !=, >, <, ...)
 * @rulestr: smack label to be audited
 * @vrule: pointer to save our own audit rule representation
 *
 * Prepare to audit cases where (@field @op @rulestr) is true.
 * The label to be audited is created if necessay.
 */
static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule)
{
        char **rule = (char **)vrule;
        *rule = NULL;

        if (field != AUDIT_SUBJ_USER && field != AUDIT_OBJ_USER)
                return -EINVAL;

        if (op != AUDIT_EQUAL && op != AUDIT_NOT_EQUAL)
                return -EINVAL;

        *rule = smk_import(rulestr, 0);

        return 0;
}

/**
 * smack_audit_rule_known - Distinguish Smack audit rules
 * @krule: rule of interest, in Audit kernel representation format
 *
 * This is used to filter Smack rules from remaining Audit ones.
 * If it's proved that this rule belongs to us, the
 * audit_rule_match hook will be called to do the final judgement.
 */
static int smack_audit_rule_known(struct audit_krule *krule)
{
        struct audit_field *f;
        int i;

        for (i = 0; i < krule->field_count; i++) {
                f = &krule->fields[i];

                if (f->type == AUDIT_SUBJ_USER || f->type == AUDIT_OBJ_USER)
                        return 1;
        }

        return 0;
}

/**
 * smack_audit_rule_match - Audit given object ?
 * @secid: security id for identifying the object to test
 * @field: audit rule flags given from user-space
 * @op: required testing operator
 * @vrule: smack internal rule presentation
 * @actx: audit context associated with the check
 *
 * The core Audit hook. It's used to take the decision of
 * whether to audit or not to audit a given object.
 */
static int smack_audit_rule_match(u32 secid, u32 field, u32 op, void *vrule,
                                  struct audit_context *actx)
{
        char *smack;
        char *rule = vrule;

        if (!rule) {
                audit_log(actx, GFP_KERNEL, AUDIT_SELINUX_ERR,
                          "Smack: missing rule\n");
                return -ENOENT;
        }

        if (field != AUDIT_SUBJ_USER && field != AUDIT_OBJ_USER)
                return 0;

        smack = smack_from_secid(secid);

        /*
         * No need to do string comparisons. If a match occurs,
         * both pointers will point to the same smack_known
         * label.
         */
        if (op == AUDIT_EQUAL)
                return (rule == smack);
        if (op == AUDIT_NOT_EQUAL)
                return (rule != smack);

        return 0;
}

/**
 * smack_audit_rule_free - free smack rule representation
 * @vrule: rule to be freed.
 *
 * No memory was allocated.
 */
static void smack_audit_rule_free(void *vrule)
{
        /* No-op */
}

#endif /* CONFIG_AUDIT */

/*
 * smack_secid_to_secctx - return the smack label for a secid
 * @secid: incoming integer
 * @secdata: destination
 * @seclen: how long it is
 *
 * Exists for networking code.
 */
static int smack_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
{
        char *sp = smack_from_secid(secid);

        *secdata = sp;
        *seclen = strlen(sp);
        return 0;
}

/*
 * smack_secctx_to_secid - return the secid for a smack label
 * @secdata: smack label
 * @seclen: how long result is
 * @secid: outgoing integer
 *
 * Exists for audit and networking code.
 */
static int smack_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
{
        *secid = smack_to_secid(secdata);
        return 0;
}

/*
 * smack_release_secctx - don't do anything.
 * @key_ref: unused
 * @context: unused
 * @perm: unused
 *
 * Exists to make sure nothing gets done, and properly
 */
static void smack_release_secctx(char *secdata, u32 seclen)
{
}

struct security_operations smack_ops = {
        .name =                         "smack",

        .ptrace_may_access =            smack_ptrace_may_access,
        .ptrace_traceme =               smack_ptrace_traceme,
        .capget =                       cap_capget,
        .capset_check =                 cap_capset_check,
        .capset_set =                   cap_capset_set,
        .capable =                      cap_capable,
        .syslog =                       smack_syslog,
        .settime =                      cap_settime,
        .vm_enough_memory =             cap_vm_enough_memory,

        .bprm_apply_creds =             cap_bprm_apply_creds,
        .bprm_set_security =            cap_bprm_set_security,
        .bprm_secureexec =              cap_bprm_secureexec,

        .sb_alloc_security =            smack_sb_alloc_security,
        .sb_free_security =             smack_sb_free_security,
        .sb_copy_data =                 smack_sb_copy_data,
        .sb_kern_mount =                smack_sb_kern_mount,
        .sb_statfs =                    smack_sb_statfs,
        .sb_mount =                     smack_sb_mount,
        .sb_umount =                    smack_sb_umount,

        .inode_alloc_security =         smack_inode_alloc_security,
        .inode_free_security =          smack_inode_free_security,
        .inode_init_security =          smack_inode_init_security,
        .inode_link =                   smack_inode_link,
        .inode_unlink =                 smack_inode_unlink,
        .inode_rmdir =                  smack_inode_rmdir,
        .inode_rename =                 smack_inode_rename,
        .inode_permission =             smack_inode_permission,
        .inode_setattr =                smack_inode_setattr,
        .inode_getattr =                smack_inode_getattr,
        .inode_setxattr =               smack_inode_setxattr,
        .inode_post_setxattr =          smack_inode_post_setxattr,
        .inode_getxattr =               smack_inode_getxattr,
        .inode_removexattr =            smack_inode_removexattr,
        .inode_need_killpriv =          cap_inode_need_killpriv,
        .inode_killpriv =               cap_inode_killpriv,
        .inode_getsecurity =            smack_inode_getsecurity,
        .inode_setsecurity =            smack_inode_setsecurity,
        .inode_listsecurity =           smack_inode_listsecurity,
        .inode_getsecid =               smack_inode_getsecid,

        .file_permission =              smack_file_permission,
        .file_alloc_security =          smack_file_alloc_security,
        .file_free_security =           smack_file_free_security,
        .file_ioctl =                   smack_file_ioctl,
        .file_lock =                    smack_file_lock,
        .file_fcntl =                   smack_file_fcntl,
        .file_set_fowner =              smack_file_set_fowner,
        .file_send_sigiotask =          smack_file_send_sigiotask,
        .file_receive =                 smack_file_receive,

        .cred_alloc_security =          smack_cred_alloc_security,
        .cred_free =                    smack_cred_free,
        .task_post_setuid =             cap_task_post_setuid,
        .task_setpgid =                 smack_task_setpgid,
        .task_getpgid =                 smack_task_getpgid,
        .task_getsid =                  smack_task_getsid,
        .task_getsecid =                smack_task_getsecid,
        .task_setnice =                 smack_task_setnice,
        .task_setioprio =               smack_task_setioprio,
        .task_getioprio =               smack_task_getioprio,
        .task_setscheduler =            smack_task_setscheduler,
        .task_getscheduler =            smack_task_getscheduler,
        .task_movememory =              smack_task_movememory,
        .task_kill =                    smack_task_kill,
        .task_wait =                    smack_task_wait,
        .task_reparent_to_init =        cap_task_reparent_to_init,
        .task_to_inode =                smack_task_to_inode,
        .task_prctl =                   cap_task_prctl,

        .ipc_permission =               smack_ipc_permission,
        .ipc_getsecid =                 smack_ipc_getsecid,

        .msg_msg_alloc_security =       smack_msg_msg_alloc_security,
        .msg_msg_free_security =        smack_msg_msg_free_security,

        .msg_queue_alloc_security =     smack_msg_queue_alloc_security,
        .msg_queue_free_security =      smack_msg_queue_free_security,
        .msg_queue_associate =          smack_msg_queue_associate,
        .msg_queue_msgctl =             smack_msg_queue_msgctl,
        .msg_queue_msgsnd =             smack_msg_queue_msgsnd,
        .msg_queue_msgrcv =             smack_msg_queue_msgrcv,

        .shm_alloc_security =           smack_shm_alloc_security,
        .shm_free_security =            smack_shm_free_security,
        .shm_associate =                smack_shm_associate,
        .shm_shmctl =                   smack_shm_shmctl,
        .shm_shmat =                    smack_shm_shmat,

        .sem_alloc_security =           smack_sem_alloc_security,
        .sem_free_security =            smack_sem_free_security,
        .sem_associate =                smack_sem_associate,
        .sem_semctl =                   smack_sem_semctl,
        .sem_semop =                    smack_sem_semop,

        .netlink_send =                 cap_netlink_send,
        .netlink_recv =                 cap_netlink_recv,

        .d_instantiate =                smack_d_instantiate,

        .getprocattr =                  smack_getprocattr,
        .setprocattr =                  smack_setprocattr,

        .unix_stream_connect =          smack_unix_stream_connect,
        .unix_may_send =                smack_unix_may_send,

        .socket_post_create =           smack_socket_post_create,
        .socket_sock_rcv_skb =          smack_socket_sock_rcv_skb,
        .socket_getpeersec_stream =     smack_socket_getpeersec_stream,
        .socket_getpeersec_dgram =      smack_socket_getpeersec_dgram,
        .sk_alloc_security =            smack_sk_alloc_security,
        .sk_free_security =             smack_sk_free_security,
        .sock_graft =                   smack_sock_graft,
        .inet_conn_request =            smack_inet_conn_request,

 /* key management security hooks */
#ifdef CONFIG_KEYS
        .key_alloc =                    smack_key_alloc,
        .key_free =                     smack_key_free,
        .key_permission =               smack_key_permission,
#endif /* CONFIG_KEYS */

 /* Audit hooks */
#ifdef CONFIG_AUDIT
        .audit_rule_init =              smack_audit_rule_init,
        .audit_rule_known =             smack_audit_rule_known,
        .audit_rule_match =             smack_audit_rule_match,
        .audit_rule_free =              smack_audit_rule_free,
#endif /* CONFIG_AUDIT */

        .secid_to_secctx =              smack_secid_to_secctx,
        .secctx_to_secid =              smack_secctx_to_secid,
        .release_secctx =               smack_release_secctx,
};

/**
 * smack_init - initialize the smack system
 *
 * Returns 0
 */
static __init int smack_init(void)
{
        if (!security_module_enable(&smack_ops))
                return 0;

        printk(KERN_INFO "Smack:  Initializing.\n");

        /*
         * Set the security state for the initial task.
         */
        current->cred->security = &smack_known_floor.smk_known;

        /*
         * Initialize locks
         */
        spin_lock_init(&smack_known_unset.smk_cipsolock);
        spin_lock_init(&smack_known_huh.smk_cipsolock);
        spin_lock_init(&smack_known_hat.smk_cipsolock);
        spin_lock_init(&smack_known_star.smk_cipsolock);
        spin_lock_init(&smack_known_floor.smk_cipsolock);
        spin_lock_init(&smack_known_invalid.smk_cipsolock);

        /*
         * Register with LSM
         */
        if (register_security(&smack_ops))
                panic("smack: Unable to register with kernel.\n");

        return 0;
}

/*
 * Smack requires early initialization in order to label
 * all processes and objects when they are created.
 */
security_initcall(smack_init);