C++ current_user_ns函数代码示例

static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
{
	struct compat_stat tmp;

	if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
		return -EOVERFLOW;

	memset(&tmp, 0, sizeof(tmp));
	tmp.st_dev = old_encode_dev(stat->dev);
	tmp.st_ino = stat->ino;
	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
		return -EOVERFLOW;
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	if (tmp.st_nlink != stat->nlink)
		return -EOVERFLOW;
	SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
	SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
	tmp.st_rdev = old_encode_dev(stat->rdev);
	if ((u64) stat->size > MAX_NON_LFS)
		return -EOVERFLOW;
	tmp.st_size = stat->size;
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_atime_nsec = stat->atime.tv_nsec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
	tmp.st_ctime = stat->ctime.tv_sec;
	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
	tmp.st_blocks = stat->blocks;
	tmp.st_blksize = stat->blksize;
	return copy_to_user(ubuf, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}

static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
				     qid_t id)
{
	switch (cmd) {
	/* these commands do not require any special privilegues */
	case Q_GETFMT:
	case Q_SYNC:
	case Q_GETINFO:
	case Q_XGETQSTAT:
	case Q_XGETQSTATV:
	case Q_XQUOTASYNC:
		break;
	/* allow to query information for dquots we "own" */
	case Q_GETQUOTA:
	case Q_XGETQUOTA:
		if ((type == USRQUOTA && uid_eq(current_euid(), make_kuid(current_user_ns(), id))) ||
		    (type == GRPQUOTA && in_egroup_p(make_kgid(current_user_ns(), id))))
			break;
		/*FALLTHROUGH*/
	default:
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
	}

	return security_quotactl(cmd, type, id, sb);
}

static int cp_compat_stat64(struct kstat *stat,
			    struct compat_stat64 __user *statbuf)
{
	int err;

	err  = put_user(huge_encode_dev(stat->dev), &statbuf->st_dev);
	err |= put_user(stat->ino, &statbuf->st_ino);
	err |= put_user(stat->mode, &statbuf->st_mode);
	err |= put_user(stat->nlink, &statbuf->st_nlink);
	err |= put_user(from_kuid_munged(current_user_ns(), stat->uid), &statbuf->st_uid);
	err |= put_user(from_kgid_munged(current_user_ns(), stat->gid), &statbuf->st_gid);
	err |= put_user(huge_encode_dev(stat->rdev), &statbuf->st_rdev);
	err |= put_user(0, (unsigned long __user *) &statbuf->__pad3[0]);
	err |= put_user(stat->size, &statbuf->st_size);
	err |= put_user(stat->blksize, &statbuf->st_blksize);
	err |= put_user(0, (unsigned int __user *) &statbuf->__pad4[0]);
	err |= put_user(0, (unsigned int __user *) &statbuf->__pad4[4]);
	err |= put_user(stat->blocks, &statbuf->st_blocks);
	err |= put_user(stat->atime.tv_sec, &statbuf->st_atime);
	err |= put_user(stat->atime.tv_nsec, &statbuf->st_atime_nsec);
	err |= put_user(stat->mtime.tv_sec, &statbuf->st_mtime);
	err |= put_user(stat->mtime.tv_nsec, &statbuf->st_mtime_nsec);
	err |= put_user(stat->ctime.tv_sec, &statbuf->st_ctime);
	err |= put_user(stat->ctime.tv_nsec, &statbuf->st_ctime_nsec);
	err |= put_user(0, &statbuf->__unused4);
	err |= put_user(0, &statbuf->__unused5);

	return err;
}

static long cp_oldabi_stat64(struct kstat *stat,
                             struct oldabi_stat64 __user *statbuf)
{
    struct oldabi_stat64 tmp;

    tmp.st_dev = huge_encode_dev(stat->dev);
    tmp.__pad1 = 0;
    tmp.__st_ino = stat->ino;
    tmp.st_mode = stat->mode;
    tmp.st_nlink = stat->nlink;
    tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
    tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
    tmp.st_rdev = huge_encode_dev(stat->rdev);
    tmp.st_size = stat->size;
    tmp.st_blocks = stat->blocks;
    tmp.__pad2 = 0;
    tmp.st_blksize = stat->blksize;
    tmp.st_atime = stat->atime.tv_sec;
    tmp.st_atime_nsec = stat->atime.tv_nsec;
    tmp.st_mtime = stat->mtime.tv_sec;
    tmp.st_mtime_nsec = stat->mtime.tv_nsec;
    tmp.st_ctime = stat->ctime.tv_sec;
    tmp.st_ctime_nsec = stat->ctime.tv_nsec;
    tmp.st_ino = stat->ino;
    return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
{
	struct stat64 tmp;

	INIT_STRUCT_STAT64_PADDING(tmp);
#ifdef CONFIG_MIPS
	/* mips has weird padding, so we don't get 64 bits there */
	tmp.st_dev = new_encode_dev(stat->dev);
	tmp.st_rdev = new_encode_dev(stat->rdev);
#else
	tmp.st_dev = huge_encode_dev(stat->dev);
	tmp.st_rdev = huge_encode_dev(stat->rdev);
#endif
	tmp.st_ino = stat->ino;
	if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
		return -EOVERFLOW;
#ifdef STAT64_HAS_BROKEN_ST_INO
	tmp.__st_ino = stat->ino;
#endif
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_atime_nsec = stat->atime.tv_nsec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
	tmp.st_ctime = stat->ctime.tv_sec;
	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
	tmp.st_size = stat->size;
	tmp.st_blocks = stat->blocks;
	tmp.st_blksize = stat->blksize;
	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

static int cp_hpux_stat(struct kstat *stat, struct hpux_stat64 __user *statbuf)
{
	struct hpux_stat64 tmp;

	/* we probably want a different split here - is hpux 12:20? */

	if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
		return -EOVERFLOW;

	memset(&tmp, 0, sizeof(tmp));
	tmp.st_dev = new_encode_dev(stat->dev);
	tmp.st_ino = stat->ino;
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
	tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
	tmp.st_rdev = new_encode_dev(stat->rdev);
	tmp.st_size = stat->size;
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_ctime = stat->ctime.tv_sec;
	tmp.st_blocks = stat->blocks;
	tmp.st_blksize = stat->blksize;
	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

/*
 * Return the uid and gid of the last request for the mount
 *
 * When reconstructing an autofs mount tree with active mounts
 * we need to re-connect to mounts that may have used the original
 * process uid and gid (or string variations of them) for mount
 * lookups within the map entry.
 */
static int autofs_dev_ioctl_requester(struct file *fp,
				      struct autofs_sb_info *sbi,
				      struct autofs_dev_ioctl *param)
{
	struct autofs_info *ino;
	struct path path;
	dev_t devid;
	int err = -ENOENT;

	/* param->path has been checked in validate_dev_ioctl() */

	devid = sbi->sb->s_dev;

	param->requester.uid = param->requester.gid = -1;

	err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
	if (err)
		goto out;

	ino = autofs_dentry_ino(path.dentry);
	if (ino) {
		err = 0;
		autofs_expire_wait(&path, 0);
		spin_lock(&sbi->fs_lock);
		param->requester.uid =
			from_kuid_munged(current_user_ns(), ino->uid);
		param->requester.gid =
			from_kgid_munged(current_user_ns(), ino->gid);
		spin_unlock(&sbi->fs_lock);
	}
	path_put(&path);
out:
	return err;
}

/*
 * Another set for IA32/LFS -- x86_64 struct stat is different due to
 * support for 64bit inode numbers.
 */
static int cp_stat64(struct stat64 __user *ubuf, struct kstat *stat)
{
	typeof(ubuf->st_uid) uid = 0;
	typeof(ubuf->st_gid) gid = 0;
	SET_UID(uid, from_kuid_munged(current_user_ns(), stat->uid));
	SET_GID(gid, from_kgid_munged(current_user_ns(), stat->gid));
	if (!access_ok(VERIFY_WRITE, ubuf, sizeof(struct stat64)) ||
	    __put_user(huge_encode_dev(stat->dev), &ubuf->st_dev) ||
	    __put_user(stat->ino, &ubuf->__st_ino) ||
	    __put_user(stat->ino, &ubuf->st_ino) ||
	    __put_user(stat->mode, &ubuf->st_mode) ||
	    __put_user(stat->nlink, &ubuf->st_nlink) ||
	    __put_user(uid, &ubuf->st_uid) ||
	    __put_user(gid, &ubuf->st_gid) ||
	    __put_user(huge_encode_dev(stat->rdev), &ubuf->st_rdev) ||
	    __put_user(stat->size, &ubuf->st_size) ||
	    __put_user(stat->atime.tv_sec, &ubuf->st_atime) ||
	    __put_user(stat->atime.tv_nsec, &ubuf->st_atime_nsec) ||
	    __put_user(stat->mtime.tv_sec, &ubuf->st_mtime) ||
	    __put_user(stat->mtime.tv_nsec, &ubuf->st_mtime_nsec) ||
	    __put_user(stat->ctime.tv_sec, &ubuf->st_ctime) ||
	    __put_user(stat->ctime.tv_nsec, &ubuf->st_ctime_nsec) ||
	    __put_user(stat->blksize, &ubuf->st_blksize) ||
	    __put_user(stat->blocks, &ubuf->st_blocks))
		return -EFAULT;
	return 0;
}

static int chown_common(struct path *path, uid_t user, gid_t group)
{
	struct inode *inode = path->dentry->d_inode;
	int error;
	struct iattr newattrs;
	kuid_t uid;
	kgid_t gid;

	uid = make_kuid(current_user_ns(), user);
	gid = make_kgid(current_user_ns(), group);

	newattrs.ia_valid =  ATTR_CTIME;
	if (user != (uid_t) -1) {
		if (!uid_valid(uid))
			return -EINVAL;
		newattrs.ia_valid |= ATTR_UID;
		newattrs.ia_uid = uid;
	}
	if (group != (gid_t) -1) {
		if (!gid_valid(gid))
			return -EINVAL;
		newattrs.ia_valid |= ATTR_GID;
		newattrs.ia_gid = gid;
	}
	if (!S_ISDIR(inode->i_mode))
		newattrs.ia_valid |=
			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
	mutex_lock(&inode->i_mutex);
	error = security_path_chown(path, uid, gid);
	if (!error)
		error = notify_change(path->dentry, &newattrs);
	mutex_unlock(&inode->i_mutex);

	return error;
}

static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
{
	int err;
	struct dentry *newdentry;
	const struct cred *old_cred;
	struct cred *override_cred;

	/* FIXME: recheck lower dentry to see if whiteout is really needed */

	err = -ENOMEM;
	override_cred = prepare_kernel_cred(NULL);
	if (!override_cred)
		goto out;

	override_cred->fsuid = make_kuid(current_user_ns(), 0);
	if (!uid_valid(override_cred->fsuid))
		override_cred->fsuid = GLOBAL_ROOT_UID;
	override_cred->fsgid = make_kgid(current_user_ns(), 0);
	if (!gid_valid(override_cred->fsgid))
		override_cred->fsgid = GLOBAL_ROOT_GID;
	old_cred = override_creds(override_cred);

	newdentry = lookup_one_len(dentry->d_name.name, upperdir,
				   dentry->d_name.len);
	err = PTR_ERR(newdentry);
	if (IS_ERR(newdentry))
		goto out_put_cred;

	/* Just been removed within the same locked region */
	WARN_ON(newdentry->d_inode);

	err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
	if (err)
		goto out_dput;

	ovl_dentry_version_inc(dentry->d_parent);

	err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
	if (err)
		vfs_unlink(upperdir->d_inode, newdentry, NULL);

out_dput:
	dput(newdentry);
out_put_cred:
	revert_creds(old_cred);
	put_cred(override_cred);
out:
	if (err) {
		/*
		 * There's no way to recover from failure to whiteout.
		 * What should we do?  Log a big fat error and... ?
		 */
		pr_err("overlayfs: ERROR - failed to whiteout '%s'\n",
		       dentry->d_name.name);
	}

	return err;
}

static int mknod_ptmx(struct super_block *sb)
{
	int mode;
	int rc = -ENOMEM;
	struct dentry *dentry;
	struct inode *inode;
	struct dentry *root = sb->s_root;
	struct pts_fs_info *fsi = DEVPTS_SB(sb);
	struct pts_mount_opts *opts = &fsi->mount_opts;
	kuid_t root_uid;
	kgid_t root_gid;

	root_uid = make_kuid(current_user_ns(), 0);
	root_gid = make_kgid(current_user_ns(), 0);
	if (!uid_valid(root_uid) || !gid_valid(root_gid))
		return -EINVAL;

	mutex_lock(&root->d_inode->i_mutex);

	/* If we have already created ptmx node, return */
	if (fsi->ptmx_dentry) {
		rc = 0;
		goto out;
	}

	dentry = d_alloc_name(root, "ptmx");
	if (!dentry) {
		printk(KERN_NOTICE "Unable to alloc dentry for ptmx node\n");
		goto out;
	}

	/*
	 * Create a new 'ptmx' node in this mount of devpts.
	 */
	inode = new_inode(sb);
	if (!inode) {
		printk(KERN_ERR "Unable to alloc inode for ptmx node\n");
		dput(dentry);
		goto out;
	}

	inode->i_ino = 2;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;

	mode = S_IFCHR|opts->ptmxmode;
	init_special_inode(inode, mode, MKDEV(TTYAUX_MAJOR, 2));
	inode->i_uid = root_uid;
	inode->i_gid = root_gid;

	d_add(dentry, inode);

	fsi->ptmx_dentry = dentry;
	rc = 0;
out:
	mutex_unlock(&root->d_inode->i_mutex);
	return rc;
}

static int parse_options(char *options, struct omfs_sb_info *sbi)
{
	char *p;
	substring_t args[MAX_OPT_ARGS];
	int option;

	if (!options)
		return 1;

	while ((p = strsep(&options, ",")) != NULL) {
		int token;
		if (!*p)
			continue;

		token = match_token(p, tokens, args);
		switch (token) {
		case Opt_uid:
			if (match_int(&args[0], &option))
				return 0;
			sbi->s_uid = make_kuid(current_user_ns(), option);
			if (!uid_valid(sbi->s_uid))
				return 0;
			break;
		case Opt_gid:
			if (match_int(&args[0], &option))
				return 0;
			sbi->s_gid = make_kgid(current_user_ns(), option);
			if (!gid_valid(sbi->s_gid))
				return 0;
			break;
		case Opt_umask:
			if (match_octal(&args[0], &option))
				return 0;
			sbi->s_fmask = sbi->s_dmask = option;
			break;
		case Opt_dmask:
			if (match_octal(&args[0], &option))
				return 0;
			sbi->s_dmask = option;
			break;
		case Opt_fmask:
			if (match_octal(&args[0], &option))
				return 0;
			sbi->s_fmask = option;
			break;
		default:
			return 0;
		}
	}
	return 1;
}

/**
 * seccomp_attach_filter: Attaches a seccomp filter to current.
 * @fprog: BPF program to install
 *
 * Returns 0 on success or an errno on failure.
 */
static long seccomp_attach_filter(struct sock_fprog *fprog)
{
	struct seccomp_filter *filter;
	unsigned long fp_size = fprog->len * sizeof(struct sock_filter);
	unsigned long total_insns = fprog->len;
	long ret;

	if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
		return -EINVAL;

	for (filter = current->seccomp.filter; filter; filter = filter->prev)
		total_insns += filter->len + 4;  /* include a 4 instr penalty */
	if (total_insns > MAX_INSNS_PER_PATH)
		return -ENOMEM;

	/*
	 * Installing a seccomp filter requires that the task have
	 * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
	 * This avoids scenarios where unprivileged tasks can affect the
	 * behavior of privileged children.
	 */
	if (!current->no_new_privs &&
			security_capable_noaudit(current_cred(),
				current_user_ns(), CAP_SYS_ADMIN) != 0)
		return -EACCES;

	/* Allocate a new seccomp_filter */
	filter = kzalloc(sizeof(struct seccomp_filter) + fp_size,
			 GFP_KERNEL|__GFP_NOWARN);
	if (!filter)
		return -ENOMEM;
	atomic_set(&filter->usage, 1);
	filter->len = fprog->len;

	/* Copy the instructions from fprog. */
	ret = -EFAULT;
	if (copy_from_user(filter->insns, fprog->filter, fp_size))
		goto fail;

	/* Check and rewrite the fprog via the skb checker */
	ret = sk_chk_filter(filter->insns, filter->len);
	if (ret)
		goto fail;

	/* Check and rewrite the fprog for seccomp use */
	ret = seccomp_check_filter(filter->insns, filter->len);
	if (ret)
		goto fail;

	/*
	 * If there is an existing filter, make it the prev and don't drop its
	 * task reference.
	 */
	filter->prev = current->seccomp.filter;
	current->seccomp.filter = filter;
	return 0;
fail:
	kfree(filter);
	return ret;
}

static struct dentry *sysfs_mount(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	struct sysfs_super_info *info;
	enum kobj_ns_type type;
	struct super_block *sb;
	int error;

	if (!(flags & MS_KERNMOUNT) && !current_user_ns()->may_mount_sysfs)
		return ERR_PTR(-EPERM);

	info = kzalloc(sizeof(*info), GFP_KERNEL);
	if (!info)
		return ERR_PTR(-ENOMEM);

	for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
		info->ns[type] = kobj_ns_grab_current(type);

	sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
	if (IS_ERR(sb) || sb->s_fs_info != info)
		free_sysfs_super_info(info);
	if (IS_ERR(sb))
		return ERR_CAST(sb);
	if (!sb->s_root) {
		error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
		if (error) {
			deactivate_locked_super(sb);
			return ERR_PTR(error);
		}
		sb->s_flags |= MS_ACTIVE;
	}

	return dget(sb->s_root);
}

static long
force_sigsegv_info (int sig, void __user *addr)
{
	unsigned long flags;
	struct siginfo si;

	clear_siginfo(&si);
	if (sig == SIGSEGV) {
		/*
		 * Acquiring siglock around the sa_handler-update is almost
		 * certainly overkill, but this isn't a
		 * performance-critical path and I'd rather play it safe
		 * here than having to debug a nasty race if and when
		 * something changes in kernel/signal.c that would make it
		 * no longer safe to modify sa_handler without holding the
		 * lock.
		 */
		spin_lock_irqsave(&current->sighand->siglock, flags);
		current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
		spin_unlock_irqrestore(&current->sighand->siglock, flags);
	}
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = task_pid_vnr(current);
	si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
	si.si_addr = addr;
	force_sig_info(SIGSEGV, &si, current);
	return 1;
}