/*
 * security/tomoyo/tomoyo.c
 *
 * LSM hooks for TOMOYO Linux.
 *
 * Copyright (C) 2005-2010  NTT DATA CORPORATION
 */

#include <linux/security.h>
#include "common.h"

static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
{
        new->security = NULL;
        return 0;
}

static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
                               gfp_t gfp)
{
        struct tomoyo_domain_info *domain = old->security;
        new->security = domain;
        if (domain)
                atomic_inc(&domain->users);
        return 0;
}

static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
{
        tomoyo_cred_prepare(new, old, 0);
}

static void tomoyo_cred_free(struct cred *cred)
{
        struct tomoyo_domain_info *domain = cred->security;
        if (domain)
                atomic_dec(&domain->users);
}

static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
{
        int rc;

        rc = cap_bprm_set_creds(bprm);
        if (rc)
                return rc;

        /*
         * Do only if this function is called for the first time of an execve
         * operation.
         */
        if (bprm->cred_prepared)
                return 0;
        /*
         * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
         * for the first time.
         */
        if (!tomoyo_policy_loaded)
                tomoyo_load_policy(bprm->filename);
        /*
         * Release reference to "struct tomoyo_domain_info" stored inside
         * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
         * stored inside "bprm->cred->security" will be acquired later inside
         * tomoyo_find_next_domain().
         */
        atomic_dec(&((struct tomoyo_domain_info *)
                     bprm->cred->security)->users);
        /*
         * Tell tomoyo_bprm_check_security() is called for the first time of an
         * execve operation.
         */
        bprm->cred->security = NULL;
        return 0;
}

static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
{
        struct tomoyo_domain_info *domain = bprm->cred->security;

        /*
         * Execute permission is checked against pathname passed to do_execve()
         * using current domain.
         */
        if (!domain) {
                const int idx = tomoyo_read_lock();
                const int err = tomoyo_find_next_domain(bprm);
                tomoyo_read_unlock(idx);
                return err;
        }
        /*
         * Read permission is checked against interpreters using next domain.
         */
        return tomoyo_check_open_permission(domain, &bprm->file->f_path, O_RDONLY);
}

static int tomoyo_path_truncate(struct path *path)
{
        return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path);
}

static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path);
}

static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
                             int mode)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
                                       mode & S_IALLUGO);
}

static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path);
}

static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
                               const char *old_name)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path);
}

static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
                             int mode, unsigned int dev)
{
        struct path path = { parent->mnt, dentry };
        int type = TOMOYO_TYPE_CREATE;
        const unsigned int perm = mode & S_IALLUGO;

        switch (mode & S_IFMT) {
        case S_IFCHR:
                type = TOMOYO_TYPE_MKCHAR;
                break;
        case S_IFBLK:
                type = TOMOYO_TYPE_MKBLOCK;
                break;
        default:
                goto no_dev;
        }
        return tomoyo_mkdev_perm(type, &path, perm, dev);
 no_dev:
        switch (mode & S_IFMT) {
        case S_IFIFO:
                type = TOMOYO_TYPE_MKFIFO;
                break;
        case S_IFSOCK:
                type = TOMOYO_TYPE_MKSOCK;
                break;
        }
        return tomoyo_path_number_perm(type, &path, perm);
}

static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
                            struct dentry *new_dentry)
{
        struct path path1 = { new_dir->mnt, old_dentry };
        struct path path2 = { new_dir->mnt, new_dentry };
        return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
}

static int tomoyo_path_rename(struct path *old_parent,
                              struct dentry *old_dentry,
                              struct path *new_parent,
                              struct dentry *new_dentry)
{
        struct path path1 = { old_parent->mnt, old_dentry };
        struct path path2 = { new_parent->mnt, new_dentry };
        return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
}

static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
                             unsigned long arg)
{
        if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
                return tomoyo_path_perm(TOMOYO_TYPE_REWRITE, &file->f_path);
        return 0;
}

static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
{
        int flags = f->f_flags;
        /* Don't check read permission here if called from do_execve(). */
        if (current->in_execve)
                return 0;
        return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
}

static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
                             unsigned long arg)
{
        return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
}

static int tomoyo_path_chmod(struct dentry *dentry, struct vfsmount *mnt,
                             mode_t mode)
{
        struct path path = { mnt, dentry };
        return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, &path,
                                       mode & S_IALLUGO);
}

static int tomoyo_path_chown(struct path *path, uid_t uid, gid_t gid)
{
        int error = 0;
        if (uid != (uid_t) -1)
                error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path, uid);
        if (!error && gid != (gid_t) -1)
                error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path, gid);
        return error;
}

static int tomoyo_path_chroot(struct path *path)
{
        return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path);
}

static int tomoyo_sb_mount(char *dev_name, struct path *path,
                           char *type, unsigned long flags, void *data)
{
        return tomoyo_mount_permission(dev_name, path, type, flags, data);
}

static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
{
        struct path path = { mnt, mnt->mnt_root };
        return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path);
}

static int tomoyo_sb_pivotroot(struct path *old_path, struct path *new_path)
{
        return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
}

/*
 * tomoyo_security_ops is a "struct security_operations" which is used for
 * registering TOMOYO.
 */
static struct security_operations tomoyo_security_ops = {
        .name                = "tomoyo",
        .cred_alloc_blank    = tomoyo_cred_alloc_blank,
        .cred_prepare        = tomoyo_cred_prepare,
        .cred_transfer       = tomoyo_cred_transfer,
        .cred_free           = tomoyo_cred_free,
        .bprm_set_creds      = tomoyo_bprm_set_creds,
        .bprm_check_security = tomoyo_bprm_check_security,
        .file_fcntl          = tomoyo_file_fcntl,
        .dentry_open         = tomoyo_dentry_open,
        .path_truncate       = tomoyo_path_truncate,
        .path_unlink         = tomoyo_path_unlink,
        .path_mkdir          = tomoyo_path_mkdir,
        .path_rmdir          = tomoyo_path_rmdir,
        .path_symlink        = tomoyo_path_symlink,
        .path_mknod          = tomoyo_path_mknod,
        .path_link           = tomoyo_path_link,
        .path_rename         = tomoyo_path_rename,
        .file_ioctl          = tomoyo_file_ioctl,
        .path_chmod          = tomoyo_path_chmod,
        .path_chown          = tomoyo_path_chown,
        .path_chroot         = tomoyo_path_chroot,
        .sb_mount            = tomoyo_sb_mount,
        .sb_umount           = tomoyo_sb_umount,
        .sb_pivotroot        = tomoyo_sb_pivotroot,
};

/* Lock for GC. */
struct srcu_struct tomoyo_ss;

static int __init tomoyo_init(void)
{
        struct cred *cred = (struct cred *) current_cred();

        if (!security_module_enable(&tomoyo_security_ops))
                return 0;
        /* register ourselves with the security framework */
        if (register_security(&tomoyo_security_ops) ||
            init_srcu_struct(&tomoyo_ss))
                panic("Failure registering TOMOYO Linux");
        printk(KERN_INFO "TOMOYO Linux initialized\n");
        cred->security = &tomoyo_kernel_domain;
        tomoyo_mm_init();
        return 0;
}

security_initcall(tomoyo_init);