Commit db340159 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'fsnotify_for_v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 

Pull fsnotify updates from Jan Kara:
 "Two fanotify cleanups and support for watching namespace-owned
  filesystems by namespace admins (most useful for being able to watch
  for new mounts / unmounts happening within a user namespace)"

* tag 'fsnotify_for_v6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fanotify: support watching filesystems and mounts inside userns
  fanotify: remove redundant permission checks
  fanotify: Drop use of flex array in fanotify_fh
parents 1193e205 58f5fbeb

fs/notify/fanotify/fanotify.c

+2 −1
Original line number Diff line number Diff line
@@ -415,7 +415,7 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode, 
{

	int dwords, type = 0;

	char *ext_buf = NULL;

	void *buf = fh->buf;

	void *buf = fh + 1;

	int err;



	fh->type = FILEID_ROOT;
@@ -1009,6 +1009,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask, 


static void fanotify_free_group_priv(struct fsnotify_group *group)

{

	put_user_ns(group->user_ns);

	kfree(group->fanotify_data.merge_hash);

	if (group->fanotify_data.ucounts)

		dec_ucount(group->fanotify_data.ucounts,

fs/notify/fanotify/fanotify.h

+4 −5
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ enum { 
 * stored in either the first or last 2 dwords.

 */

#define FANOTIFY_INLINE_FH_LEN	(3 << 2)

#define FANOTIFY_FH_HDR_LEN	offsetof(struct fanotify_fh, buf)

#define FANOTIFY_FH_HDR_LEN	sizeof(struct fanotify_fh)



/* Fixed size struct for file handle */

struct fanotify_fh {
@@ -34,7 +34,6 @@ struct fanotify_fh { 
#define FANOTIFY_FH_FLAG_EXT_BUF 1

	u8 flags;

	u8 pad;

	unsigned char buf[];

} __aligned(4);



/* Variable size struct for dir file handle + child file handle + name */
@@ -92,7 +91,7 @@ static inline char **fanotify_fh_ext_buf_ptr(struct fanotify_fh *fh) 
	BUILD_BUG_ON(FANOTIFY_FH_HDR_LEN % 4);

	BUILD_BUG_ON(__alignof__(char *) - 4 + sizeof(char *) >

		     FANOTIFY_INLINE_FH_LEN);

	return (char **)ALIGN((unsigned long)(fh->buf), __alignof__(char *));

	return (char **)ALIGN((unsigned long)(fh + 1), __alignof__(char *));

}



static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh)
@@ -102,7 +101,7 @@ static inline void *fanotify_fh_ext_buf(struct fanotify_fh *fh) 


static inline void *fanotify_fh_buf(struct fanotify_fh *fh)

{

	return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh->buf;

	return fanotify_fh_has_ext_buf(fh) ? fanotify_fh_ext_buf(fh) : fh + 1;

}



static inline int fanotify_info_dir_fh_len(struct fanotify_info *info)
@@ -278,7 +277,7 @@ static inline void fanotify_init_event(struct fanotify_event *event, 
#define FANOTIFY_INLINE_FH(name, size)					\

struct {								\

	struct fanotify_fh name;					\

	/* Space for object_fh.buf[] - access with fanotify_fh_buf() */	\

	/* Space for filehandle - access with fanotify_fh_buf() */	\

	unsigned char _inline_fh_buf[size];				\

}

fs/notify/fanotify/fanotify_user.c

+29 −21
Original line number Diff line number Diff line
@@ -1334,6 +1334,7 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, 
	 * A group with FAN_UNLIMITED_MARKS does not contribute to mark count

	 * in the limited groups account.

	 */

	BUILD_BUG_ON(!(FANOTIFY_ADMIN_INIT_FLAGS & FAN_UNLIMITED_MARKS));

	if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) &&

	    !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS))

		return ERR_PTR(-ENOSPC);
@@ -1498,6 +1499,7 @@ static struct hlist_head *fanotify_alloc_merge_hash(void) 
/* fanotify syscalls */

SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)

{

	struct user_namespace *user_ns = current_user_ns();

	struct fsnotify_group *group;

	int f_flags, fd;

	unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
@@ -1512,10 +1514,11 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
		/*

		 * An unprivileged user can setup an fanotify group with

		 * limited functionality - an unprivileged group is limited to

		 * notification events with file handles and it cannot use

		 * unlimited queue/marks.

		 * notification events with file handles or mount ids and it

		 * cannot use unlimited queue/marks.

		 */

		if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode)

		if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) ||

		    !(flags & (FANOTIFY_FID_BITS | FAN_REPORT_MNT)))

			return -EPERM;



		/*
@@ -1594,8 +1597,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	}



	/* Enforce groups limits per user in all containing user ns */

	group->fanotify_data.ucounts = inc_ucount(current_user_ns(),

						  current_euid(),

	group->fanotify_data.ucounts = inc_ucount(user_ns, current_euid(),

						  UCOUNT_FANOTIFY_GROUPS);

	if (!group->fanotify_data.ucounts) {

		fd = -EMFILE;
@@ -1604,6 +1606,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 


	group->fanotify_data.flags = flags | internal_flags;

	group->memcg = get_mem_cgroup_from_mm(current->mm);

	group->user_ns = get_user_ns(user_ns);



	group->fanotify_data.merge_hash = fanotify_alloc_merge_hash();

	if (!group->fanotify_data.merge_hash) {
@@ -1637,21 +1640,13 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
		goto out_destroy_group;

	}



	BUILD_BUG_ON(!(FANOTIFY_ADMIN_INIT_FLAGS & FAN_UNLIMITED_QUEUE));

	if (flags & FAN_UNLIMITED_QUEUE) {

		fd = -EPERM;

		if (!capable(CAP_SYS_ADMIN))

			goto out_destroy_group;

		group->max_events = UINT_MAX;

	} else {

		group->max_events = fanotify_max_queued_events;

	}



	if (flags & FAN_UNLIMITED_MARKS) {

		fd = -EPERM;

		if (!capable(CAP_SYS_ADMIN))

			goto out_destroy_group;

	}



	if (flags & FAN_ENABLE_AUDIT) {

		fd = -EPERM;

		if (!capable(CAP_AUDIT_WRITE))
@@ -1811,6 +1806,8 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 
	struct fsnotify_group *group;

	struct path path;

	struct fan_fsid __fsid, *fsid = NULL;

	struct user_namespace *user_ns = NULL;

	struct mnt_namespace *mntns;

	u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;

	unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;

	unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS;
@@ -1904,12 +1901,10 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 
	}



	/*

	 * An unprivileged user is not allowed to setup mount nor filesystem

	 * marks.  This also includes setting up such marks by a group that

	 * was initialized by an unprivileged user.

	 * A user is allowed to setup sb/mount/mntns marks only if it is

	 * capable in the user ns where the group was created.

	 */

	if ((!capable(CAP_SYS_ADMIN) ||

	     FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) &&

	if (!ns_capable(group->user_ns, CAP_SYS_ADMIN) &&

	    mark_type != FAN_MARK_INODE)

		return -EPERM;
@@ -1988,18 +1983,31 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 
		fsid = &__fsid;

	}



	/* inode held in place by reference to path; group by fget on fd */

	/*

	 * In addition to being capable in the user ns where group was created,

	 * the user also needs to be capable in the user ns associated with

	 * the filesystem or in the user ns associated with the mntns

	 * (when marking mntns).

	 */

	if (obj_type == FSNOTIFY_OBJ_TYPE_INODE) {

		inode = path.dentry->d_inode;

		obj = inode;

	} else if (obj_type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) {

		user_ns = path.mnt->mnt_sb->s_user_ns;

		obj = path.mnt;

	} else if (obj_type == FSNOTIFY_OBJ_TYPE_SB) {

		user_ns = path.mnt->mnt_sb->s_user_ns;

		obj = path.mnt->mnt_sb;

	} else if (obj_type == FSNOTIFY_OBJ_TYPE_MNTNS) {

		obj = mnt_ns_from_dentry(path.dentry);

		mntns = mnt_ns_from_dentry(path.dentry);

		user_ns = mntns->user_ns;

		obj = mntns;

	}



	ret = -EPERM;

	if (user_ns && !ns_capable(user_ns, CAP_SYS_ADMIN))

		goto path_put_and_out;



	ret = -EINVAL;

	if (!obj)

		goto path_put_and_out;

include/linux/fanotify.h

+2 −3
Original line number Diff line number Diff line
@@ -38,8 +38,7 @@ 
					 FAN_REPORT_PIDFD | \

					 FAN_REPORT_FD_ERROR | \

					 FAN_UNLIMITED_QUEUE | \

					 FAN_UNLIMITED_MARKS | \

					 FAN_REPORT_MNT)

					 FAN_UNLIMITED_MARKS)



/*

 * fanotify_init() flags that are allowed for user without CAP_SYS_ADMIN.
@@ -48,7 +47,7 @@ 
 * so one of the flags for reporting file handles is required.

 */

#define FANOTIFY_USER_INIT_FLAGS	(FAN_CLASS_NOTIF | \

					 FANOTIFY_FID_BITS | \

					 FANOTIFY_FID_BITS | FAN_REPORT_MNT | \

					 FAN_CLOEXEC | FAN_NONBLOCK)



#define FANOTIFY_INIT_FLAGS	(FANOTIFY_ADMIN_INIT_FLAGS | \

include/linux/fsnotify_backend.h

+1 −0
Original line number Diff line number Diff line
@@ -250,6 +250,7 @@ struct fsnotify_group { 
						 * full */



	struct mem_cgroup *memcg;	/* memcg to charge allocations */

	struct user_namespace *user_ns;	/* user ns where group was created */



	/* groups can define private fields here or use the void *private */

	union {