/*
 * security/tomoyo/tomoyo.c
 *
 * LSM hooks for TOMOYO Linux.
 *
 * Copyright (C) 2005-2009  NTT DATA CORPORATION
 *
 * Version: 2.2.0   2009/04/01
 *
 */

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

static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
                               gfp_t gfp)
{
        /*
         * Since "struct tomoyo_domain_info *" is a sharable pointer,
         * we don't need to duplicate.
         */
        new->security = old->security;
        return 0;
}

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);
        /*
         * 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) {
                struct tomoyo_domain_info *next_domain = NULL;
                int retval = tomoyo_find_next_domain(bprm, &next_domain);

                if (!retval)
                        bprm->cred->security = next_domain;
                return retval;
        }
        /*
         * Read permission is checked against interpreters using next domain.
         * '1' is the result of open_to_namei_flags(O_RDONLY).
         */
        return tomoyo_check_open_permission(domain, &bprm->file->f_path, 1);
}

#ifdef CONFIG_SYSCTL

static int tomoyo_prepend(char **buffer, int *buflen, const char *str)
{
        int namelen = strlen(str);

        if (*buflen < namelen)
                return -ENOMEM;
        *buflen -= namelen;
        *buffer -= namelen;
        memcpy(*buffer, str, namelen);
        return 0;
}

/**
 * tomoyo_sysctl_path - return the realpath of a ctl_table.
 * @table: pointer to "struct ctl_table".
 *
 * Returns realpath(3) of the @table on success.
 * Returns NULL on failure.
 *
 * This function uses tomoyo_alloc(), so the caller must call tomoyo_free()
 * if this function didn't return NULL.
 */
static char *tomoyo_sysctl_path(struct ctl_table *table)
{
        int buflen = TOMOYO_MAX_PATHNAME_LEN;
        char *buf = tomoyo_alloc(buflen);
        char *end = buf + buflen;
        int error = -ENOMEM;

        if (!buf)
                return NULL;

        *--end = '\0';
        buflen--;
        while (table) {
                char num[32];
                const char *sp = table->procname;

                if (!sp) {
                        memset(num, 0, sizeof(num));
                        snprintf(num, sizeof(num) - 1, "=%d=", table->ctl_name);
                        sp = num;
                }
                if (tomoyo_prepend(&end, &buflen, sp) ||
                    tomoyo_prepend(&end, &buflen, "/"))
                        goto out;
                table = table->parent;
        }
        if (tomoyo_prepend(&end, &buflen, "/proc/sys"))
                goto out;
        error = tomoyo_encode(buf, end - buf, end);
 out:
        if (!error)
                return buf;
        tomoyo_free(buf);
        return NULL;
}

static int tomoyo_sysctl(struct ctl_table *table, int op)
{
        int error;
        char *name;

        op &= MAY_READ | MAY_WRITE;
        if (!op)
                return 0;
        name = tomoyo_sysctl_path(table);
        if (!name)
                return -ENOMEM;
        error = tomoyo_check_file_perm(tomoyo_domain(), name, op);
        tomoyo_free(name);
        return error;
}
#endif

static int tomoyo_path_truncate(struct path *path, loff_t length,
                                unsigned int time_attrs)
{
        return tomoyo_check_1path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_TRUNCATE_ACL,
                                       path);
}

static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_check_1path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_UNLINK_ACL,
                                       &path);
}

static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
                             int mode)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_check_1path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_MKDIR_ACL,
                                       &path);
}

static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_check_1path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_RMDIR_ACL,
                                       &path);
}

static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
                               const char *old_name)
{
        struct path path = { parent->mnt, dentry };
        return tomoyo_check_1path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_SYMLINK_ACL,
                                       &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_ACL;

        switch (mode & S_IFMT) {
        case S_IFCHR:
                type = TOMOYO_TYPE_MKCHAR_ACL;
                break;
        case S_IFBLK:
                type = TOMOYO_TYPE_MKBLOCK_ACL;
                break;
        case S_IFIFO:
                type = TOMOYO_TYPE_MKFIFO_ACL;
                break;
        case S_IFSOCK:
                type = TOMOYO_TYPE_MKSOCK_ACL;
                break;
        }
        return tomoyo_check_1path_perm(tomoyo_domain(),
                                       type, &path);
}

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_check_2path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_LINK_ACL,
                                       &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_check_2path_perm(tomoyo_domain(),
                                       TOMOYO_TYPE_RENAME_ACL,
                                       &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_check_rewrite_permission(tomoyo_domain(), file);
        return 0;
}

static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
{
        int flags = f->f_flags;

        if ((flags + 1) & O_ACCMODE)
                flags++;
        flags |= f->f_flags & (O_APPEND | O_TRUNC);
        /* 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 struct security_operations tomoyo_security_ops = {
        .name                = "tomoyo",
        .cred_prepare        = tomoyo_cred_prepare,
        .bprm_set_creds      = tomoyo_bprm_set_creds,
        .bprm_check_security = tomoyo_bprm_check_security,
#ifdef CONFIG_SYSCTL
        .sysctl              = tomoyo_sysctl,
#endif
        .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,
};

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))
                panic("Failure registering TOMOYO Linux");
        printk(KERN_INFO "TOMOYO Linux initialized\n");
        cred->security = &tomoyo_kernel_domain;
        tomoyo_realpath_init();
        return 0;
}

security_initcall(tomoyo_init);