Unverified Commit 474f7825 authored by Christian Brauner's avatar Christian Brauner
Browse files

fs: add copy_mount_setattr() helper 

Split out copy_mount_setattr() from mount_setattr() so we can use it in
later patches.

Link: https://lore.kernel.org/r/20250128-work-mnt_idmap-update-v2-v1-2-c25feb0d2eb3@kernel.org


Reviewed-by: default avatar"Seth Forshee (DigitalOcean)" <sforshee@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 901766df

fs/namespace.c

+40 −33
Original line number Diff line number Diff line
@@ -4814,7 +4814,7 @@ static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) 
}



static int build_mount_idmapped(const struct mount_attr *attr, size_t usize,

				struct mount_kattr *kattr, unsigned int flags)

				struct mount_kattr *kattr)

{

	struct ns_common *ns;

	struct user_namespace *mnt_userns;
@@ -4865,22 +4865,8 @@ static int build_mount_idmapped(const struct mount_attr *attr, size_t usize, 
}



static int build_mount_kattr(const struct mount_attr *attr, size_t usize,

			     struct mount_kattr *kattr, unsigned int flags)

			     struct mount_kattr *kattr)

{

	unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;



	if (flags & AT_NO_AUTOMOUNT)

		lookup_flags &= ~LOOKUP_AUTOMOUNT;

	if (flags & AT_SYMLINK_NOFOLLOW)

		lookup_flags &= ~LOOKUP_FOLLOW;

	if (flags & AT_EMPTY_PATH)

		lookup_flags |= LOOKUP_EMPTY;



	*kattr = (struct mount_kattr) {

		.lookup_flags	= lookup_flags,

		.recurse	= !!(flags & AT_RECURSIVE),

	};



	if (attr->propagation & ~MOUNT_SETATTR_PROPAGATION_FLAGS)

		return -EINVAL;

	if (hweight32(attr->propagation & MOUNT_SETATTR_PROPAGATION_FLAGS) > 1)
@@ -4928,7 +4914,7 @@ static int build_mount_kattr(const struct mount_attr *attr, size_t usize, 
			return -EINVAL;

	}



	return build_mount_idmapped(attr, usize, kattr, flags);

	return build_mount_idmapped(attr, usize, kattr);

}



static void finish_mount_kattr(struct mount_kattr *kattr)
@@ -4940,23 +4926,14 @@ static void finish_mount_kattr(struct mount_kattr *kattr) 
		mnt_idmap_put(kattr->mnt_idmap);

}



SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,

		unsigned int, flags, struct mount_attr __user *, uattr,

		size_t, usize)

static int copy_mount_setattr(struct mount_attr __user *uattr, size_t usize,

			      struct mount_kattr *kattr)

{

	int err;

	struct path target;

	int ret;

	struct mount_attr attr;

	struct mount_kattr kattr;



	BUILD_BUG_ON(sizeof(struct mount_attr) != MOUNT_ATTR_SIZE_VER0);



	if (flags & ~(AT_EMPTY_PATH |

		      AT_RECURSIVE |

		      AT_SYMLINK_NOFOLLOW |

		      AT_NO_AUTOMOUNT))

		return -EINVAL;



	if (unlikely(usize > PAGE_SIZE))

		return -E2BIG;

	if (unlikely(usize < MOUNT_ATTR_SIZE_VER0))
@@ -4965,9 +4942,9 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path, 
	if (!may_mount())

		return -EPERM;



	err = copy_struct_from_user(&attr, sizeof(attr), uattr, usize);

	if (err)

		return err;

	ret = copy_struct_from_user(&attr, sizeof(attr), uattr, usize);

	if (ret)

		return ret;



	/* Don't bother walking through the mounts if this is a nop. */

	if (attr.attr_set == 0 &&
@@ -4975,7 +4952,37 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path, 
	    attr.propagation == 0)

		return 0;



	err = build_mount_kattr(&attr, usize, &kattr, flags);

	return build_mount_kattr(&attr, usize, kattr);

}



SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,

		unsigned int, flags, struct mount_attr __user *, uattr,

		size_t, usize)

{

	int err;

	struct path target;

	struct mount_kattr kattr;

	unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW;



	if (flags & ~(AT_EMPTY_PATH |

		      AT_RECURSIVE |

		      AT_SYMLINK_NOFOLLOW |

		      AT_NO_AUTOMOUNT))

		return -EINVAL;



	if (flags & AT_NO_AUTOMOUNT)

		lookup_flags &= ~LOOKUP_AUTOMOUNT;

	if (flags & AT_SYMLINK_NOFOLLOW)

		lookup_flags &= ~LOOKUP_FOLLOW;

	if (flags & AT_EMPTY_PATH)

		lookup_flags |= LOOKUP_EMPTY;



	kattr = (struct mount_kattr) {

		.lookup_flags	= lookup_flags,

		.recurse	= !!(flags & AT_RECURSIVE),

	};



	err = copy_mount_setattr(uattr, usize, &kattr);

	if (err)

		return err;