// SPDX-License-Identifier: GPL-2.0
/*
 * security/tomoyo/tomoyo.c
 *
 * Copyright (C) 2005-2011  NTT DATA CORPORATION
 */

#include <linux/lsm_hooks.h>
#include <uapi/linux/lsm.h>
#include "common.h"

/**
 * tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
 *
 * Returns pointer to "struct tomoyo_domain_info" for current thread.
 */
struct tomoyo_domain_info *tomoyo_domain(void)
{
        struct tomoyo_task *s = tomoyo_task(current);

        if (s->old_domain_info && !current->in_execve) {
                atomic_dec(&s->old_domain_info->users);
                s->old_domain_info = NULL;
        }
        return s->domain_info;
}

/**
 * tomoyo_cred_prepare - Target for security_prepare_creds().
 *
 * @new: Pointer to "struct cred".
 * @old: Pointer to "struct cred".
 * @gfp: Memory allocation flags.
 *
 * Returns 0.
 */
static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
                               gfp_t gfp)
{
        /* Restore old_domain_info saved by previous execve() request. */
        struct tomoyo_task *s = tomoyo_task(current);

        if (s->old_domain_info && !current->in_execve) {
                atomic_dec(&s->domain_info->users);
                s->domain_info = s->old_domain_info;
                s->old_domain_info = NULL;
        }
        return 0;
}

/**
 * tomoyo_bprm_committed_creds - Target for security_bprm_committed_creds().
 *
 * @bprm: Pointer to "struct linux_binprm".
 */
static void tomoyo_bprm_committed_creds(const struct linux_binprm *bprm)
{
        /* Clear old_domain_info saved by execve() request. */
        struct tomoyo_task *s = tomoyo_task(current);

        atomic_dec(&s->old_domain_info->users);
        s->old_domain_info = NULL;
}

#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
/**
 * tomoyo_bprm_creds_for_exec - Target for security_bprm_creds_for_exec().
 *
 * @bprm: Pointer to "struct linux_binprm".
 *
 * Returns 0.
 */
static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
{
        /*
         * 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);
        return 0;
}
#endif

/**
 * tomoyo_bprm_check_security - Target for security_bprm_check().
 *
 * @bprm: Pointer to "struct linux_binprm".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
{
        struct tomoyo_task *s = tomoyo_task(current);

        /*
         * Execute permission is checked against pathname passed to execve()
         * using current domain.
         */
        if (!s->old_domain_info) {
                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(s->domain_info,
                                            &bprm->file->f_path, O_RDONLY);
}

/**
 * tomoyo_inode_getattr - Target for security_inode_getattr().
 *
 * @path: Pointer to "struct path".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_inode_getattr(const struct path *path)
{
        return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, path, NULL);
}

/**
 * tomoyo_path_truncate - Target for security_path_truncate().
 *
 * @path: Pointer to "struct path".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_truncate(const struct path *path)
{
        return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
}

/**
 * tomoyo_file_truncate - Target for security_file_truncate().
 *
 * @file: Pointer to "struct file".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_file_truncate(struct file *file)
{
        return tomoyo_path_truncate(&file->f_path);
}

/**
 * tomoyo_path_unlink - Target for security_path_unlink().
 *
 * @parent: Pointer to "struct path".
 * @dentry: Pointer to "struct dentry".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
{
        struct path path = { .mnt = parent->mnt, .dentry = dentry };

        return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
}

/**
 * tomoyo_path_mkdir - Target for security_path_mkdir().
 *
 * @parent: Pointer to "struct path".
 * @dentry: Pointer to "struct dentry".
 * @mode:   DAC permission mode.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
                             umode_t mode)
{
        struct path path = { .mnt = parent->mnt, .dentry = dentry };

        return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
                                       mode & S_IALLUGO);
}

/**
 * tomoyo_path_rmdir - Target for security_path_rmdir().
 *
 * @parent: Pointer to "struct path".
 * @dentry: Pointer to "struct dentry".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
{
        struct path path = { .mnt = parent->mnt, .dentry = dentry };

        return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
}

/**
 * tomoyo_path_symlink - Target for security_path_symlink().
 *
 * @parent:   Pointer to "struct path".
 * @dentry:   Pointer to "struct dentry".
 * @old_name: Symlink's content.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
                               const char *old_name)
{
        struct path path = { .mnt = parent->mnt, .dentry = dentry };

        return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
}

/**
 * tomoyo_path_mknod - Target for security_path_mknod().
 *
 * @parent: Pointer to "struct path".
 * @dentry: Pointer to "struct dentry".
 * @mode:   DAC permission mode.
 * @dev:    Device attributes.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
                             umode_t mode, unsigned int dev)
{
        struct path path = { .mnt = parent->mnt, .dentry = 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);
}

/**
 * tomoyo_path_link - Target for security_path_link().
 *
 * @old_dentry: Pointer to "struct dentry".
 * @new_dir:    Pointer to "struct path".
 * @new_dentry: Pointer to "struct dentry".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
                            struct dentry *new_dentry)
{
        struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
        struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };

        return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
}

/**
 * tomoyo_path_rename - Target for security_path_rename().
 *
 * @old_parent: Pointer to "struct path".
 * @old_dentry: Pointer to "struct dentry".
 * @new_parent: Pointer to "struct path".
 * @new_dentry: Pointer to "struct dentry".
 * @flags: Rename options.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_rename(const struct path *old_parent,
                              struct dentry *old_dentry,
                              const struct path *new_parent,
                              struct dentry *new_dentry,
                              const unsigned int flags)
{
        struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
        struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };

        if (flags & RENAME_EXCHANGE) {
                const int err = tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path2,
                                &path1);

                if (err)
                        return err;
        }
        return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
}

/**
 * tomoyo_file_fcntl - Target for security_file_fcntl().
 *
 * @file: Pointer to "struct file".
 * @cmd:  Command for fcntl().
 * @arg:  Argument for @cmd.
 *
 * Returns 0 on success, negative value otherwise.
 */
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 0;
        return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
                                            O_WRONLY | (arg & O_APPEND));
}

/**
 * tomoyo_file_open - Target for security_file_open().
 *
 * @f: Pointer to "struct file".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_file_open(struct file *f)
{
        /* Don't check read permission here if called from execve(). */
        /* Illogically, FMODE_EXEC is in f_flags, not f_mode. */
        if (f->f_flags & __FMODE_EXEC)
                return 0;
        return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
                                            f->f_flags);
}

/**
 * tomoyo_file_ioctl - Target for security_file_ioctl().
 *
 * @file: Pointer to "struct file".
 * @cmd:  Command for ioctl().
 * @arg:  Argument for @cmd.
 *
 * Returns 0 on success, negative value otherwise.
 */
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);
}

/**
 * tomoyo_path_chmod - Target for security_path_chmod().
 *
 * @path: Pointer to "struct path".
 * @mode: DAC permission mode.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_chmod(const struct path *path, umode_t mode)
{
        return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
                                       mode & S_IALLUGO);
}

/**
 * tomoyo_path_chown - Target for security_path_chown().
 *
 * @path: Pointer to "struct path".
 * @uid:  Owner ID.
 * @gid:  Group ID.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
{
        int error = 0;

        if (uid_valid(uid))
                error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
                                                from_kuid(&init_user_ns, uid));
        if (!error && gid_valid(gid))
                error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
                                                from_kgid(&init_user_ns, gid));
        return error;
}

/**
 * tomoyo_path_chroot - Target for security_path_chroot().
 *
 * @path: Pointer to "struct path".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_path_chroot(const struct path *path)
{
        return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
}

/**
 * tomoyo_sb_mount - Target for security_sb_mount().
 *
 * @dev_name: Name of device file. Maybe NULL.
 * @path:     Pointer to "struct path".
 * @type:     Name of filesystem type. Maybe NULL.
 * @flags:    Mount options.
 * @data:     Optional data. Maybe NULL.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
                           const char *type, unsigned long flags, void *data)
{
        return tomoyo_mount_permission(dev_name, path, type, flags, data);
}

/**
 * tomoyo_sb_umount - Target for security_sb_umount().
 *
 * @mnt:   Pointer to "struct vfsmount".
 * @flags: Unmount options.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
{
        struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };

        return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
}

/**
 * tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
 *
 * @old_path: Pointer to "struct path".
 * @new_path: Pointer to "struct path".
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
{
        return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
}

/**
 * tomoyo_socket_listen - Check permission for listen().
 *
 * @sock:    Pointer to "struct socket".
 * @backlog: Backlog parameter.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_socket_listen(struct socket *sock, int backlog)
{
        return tomoyo_socket_listen_permission(sock);
}

/**
 * tomoyo_socket_connect - Check permission for connect().
 *
 * @sock:     Pointer to "struct socket".
 * @addr:     Pointer to "struct sockaddr".
 * @addr_len: Size of @addr.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
                                 int addr_len)
{
        return tomoyo_socket_connect_permission(sock, addr, addr_len);
}

/**
 * tomoyo_socket_bind - Check permission for bind().
 *
 * @sock:     Pointer to "struct socket".
 * @addr:     Pointer to "struct sockaddr".
 * @addr_len: Size of @addr.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
                              int addr_len)
{
        return tomoyo_socket_bind_permission(sock, addr, addr_len);
}

/**
 * tomoyo_socket_sendmsg - Check permission for sendmsg().
 *
 * @sock: Pointer to "struct socket".
 * @msg:  Pointer to "struct msghdr".
 * @size: Size of message.
 *
 * Returns 0 on success, negative value otherwise.
 */
static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
                                 int size)
{
        return tomoyo_socket_sendmsg_permission(sock, msg, size);
}

struct lsm_blob_sizes tomoyo_blob_sizes __ro_after_init = {
        .lbs_task = sizeof(struct tomoyo_task),
};

/**
 * tomoyo_task_alloc - Target for security_task_alloc().
 *
 * @task:        Pointer to "struct task_struct".
 * @clone_flags: clone() flags.
 *
 * Returns 0.
 */
static int tomoyo_task_alloc(struct task_struct *task,
                             u64 clone_flags)
{
        struct tomoyo_task *old = tomoyo_task(current);
        struct tomoyo_task *new = tomoyo_task(task);

        new->domain_info = old->domain_info;
        atomic_inc(&new->domain_info->users);
        new->old_domain_info = NULL;
        return 0;
}

/**
 * tomoyo_task_free - Target for security_task_free().
 *
 * @task: Pointer to "struct task_struct".
 */
static void tomoyo_task_free(struct task_struct *task)
{
        struct tomoyo_task *s = tomoyo_task(task);

        if (s->domain_info) {
                atomic_dec(&s->domain_info->users);
                s->domain_info = NULL;
        }
        if (s->old_domain_info) {
                atomic_dec(&s->old_domain_info->users);
                s->old_domain_info = NULL;
        }
}

static const struct lsm_id tomoyo_lsmid = {
        .name = "tomoyo",
        .id = LSM_ID_TOMOYO,
};

/* tomoyo_hooks is used for registering TOMOYO. */
static struct security_hook_list tomoyo_hooks[] __ro_after_init = {
        LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
        LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
        LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
        LSM_HOOK_INIT(task_free, tomoyo_task_free),
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
        LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
#endif
        LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
        LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
        LSM_HOOK_INIT(file_open, tomoyo_file_open),
        LSM_HOOK_INIT(file_truncate, tomoyo_file_truncate),
        LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
        LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
        LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
        LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
        LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
        LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
        LSM_HOOK_INIT(path_link, tomoyo_path_link),
        LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
        LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
        LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
        LSM_HOOK_INIT(file_ioctl_compat, tomoyo_file_ioctl),
        LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
        LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
        LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
        LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
        LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
        LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
        LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
        LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
        LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
        LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
};

/* Lock for GC. */
DEFINE_SRCU(tomoyo_ss);

int tomoyo_enabled __ro_after_init = 1;

/**
 * tomoyo_init - Register TOMOYO Linux as a LSM module.
 *
 * Returns 0.
 */
static int __init tomoyo_init(void)
{
        struct tomoyo_task *s = tomoyo_task(current);

        /* register ourselves with the security framework */
        security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks),
                           &tomoyo_lsmid);
        pr_info("TOMOYO Linux initialized\n");
        s->domain_info = &tomoyo_kernel_domain;
        atomic_inc(&tomoyo_kernel_domain.users);
        s->old_domain_info = NULL;
        tomoyo_mm_init();

        return 0;
}

DEFINE_LSM(tomoyo) = {
        .id = &tomoyo_lsmid,
        .enabled = &tomoyo_enabled,
        .flags = LSM_FLAG_LEGACY_MAJOR,
        .blobs = &tomoyo_blob_sizes,
        .init = tomoyo_init,
        .initcall_fs = tomoyo_interface_init,
};