Lines Matching refs:the
8 the kernel interface.
12 The process(es) providing the data and metadata of the filesystem.
17 The filesystem daemon is running with the privileges of the mounting
18 user. NOTE: this is not the same as mounts allowed with the "user"
23 A connection between the filesystem daemon and the kernel. The
24 connection exists until either the daemon dies, or the filesystem is
25 umounted. Note that detaching (or lazy umounting) the filesystem
26 does _not_ break the connection, in this case it will exist until
27 the last reference to the filesystem is released.
31 The user who does the mounting.
44 One of the most important features of FUSE is allowing secure,
45 non-privileged mounts. This opens up new possibilities for the use of
47 using the sftp protocol.
49 The userspace library and utilities are available from the FUSE
57 The filesystem type given to mount(2) can be one of the following:
61 This is the usual way to mount a FUSE filesystem. The first
62 argument of the mount system call may contain an arbitrary string,
63 which is not interpreted by the kernel.
67 The filesystem is block device based. The first argument of the
68 mount system call is interpreted as the name of the device.
75 The file descriptor to use for communication between the userspace
76 filesystem and the kernel. The file descriptor must have been
77 obtained by opening the FUSE device ('/dev/fuse').
81 The file mode of the filesystem's root in octal representation.
85 The numeric user id of the mount owner.
89 The numeric group id of the mount owner.
93 By default FUSE doesn't check file access permissions, the
95 the underlying file access mechanism (e.g. in case of network
97 access based on file mode. It is usually useful together with the
102 This option overrides the security measure restricting file access
103 to the user mounting the filesystem. This option is by default only
109 With this option the maximum size of read operations can be set.
110 The default is infinite. Note that the size of read requests is
115 Set the block size for the filesystem. The default is 512. This
125 Mounting it under the '/sys/fs/fuse/connections' directory makes it
128 Under the fuse control filesystem each connection has a directory
131 For each connection the following files exist within this directory:
136 userspace or being processed by the filesystem daemon. If there is
137 no filesystem activity and 'waiting' is non-zero, then the
142 Writing anything into this file will abort the filesystem
146 Only the owner of the mount may read or write these files.
151 If a process issuing a FUSE filesystem request is interrupted, the
154 1) If the request is not yet sent to userspace AND the signal is
155 fatal (SIGKILL or unhandled fatal signal), then the request is
158 2) If the request is not yet sent to userspace AND the signal is not
159 fatal, then an 'interrupted' flag is set for the request. When
160 the request has been successfully transferred to userspace and
163 3) If the request is already sent to userspace, then an INTERRUPT
166 INTERRUPT requests take precedence over other requests, so the
169 The userspace filesystem may ignore the INTERRUPT requests entirely,
170 or may honor them by sending a reply to the _original_ request, with
171 the error set to EINTR.
173 It is also possible that there's a race between processing the
176 1) The INTERRUPT request is processed before the original request is
179 2) The INTERRUPT request is processed after the original request has
182 If the filesystem cannot find the original request, it should wait for
184 should reply to the INTERRUPT request with an EAGAIN error. In case
185 1) the INTERRUPT request will be requeued. In case 2) the INTERRUPT
191 It is possible to get into certain situations where the filesystem is
204 In either of these cases it may be useful to abort the connection to
205 the filesystem. There are several ways to do this:
207 - Kill the filesystem daemon. Works in case of a) and b)
209 - Kill the filesystem daemon and all users of the filesystem. Works
215 - Abort filesystem through the FUSE control filesystem. Most
221 Since the mount() system call is a privileged operation, a helper
224 The implication of providing non-privileged mounts is that the mount
225 owner must not be able to use this capability to compromise the
228 A) mount owner should not be able to get elevated privileges with the
229 help of the mounted filesystem
232 other users' and the super user's processes
235 other users' or the super user's processes
250 fusermount always adds "nosuid" and "nodev" to the mount options
253 B) If another user is accessing files or directories in the
254 filesystem, the filesystem daemon serving requests can record the
256 information is otherwise inaccessible to the mount owner, so this
261 C) There are several ways in which the mount owner can induce
264 1) mounting a filesystem over a file or directory which the mount
268 This is solved in fusermount, by checking the access
269 permissions on the mountpoint and only allowing the mount if
270 the mount owner can do unlimited modification (has write
271 access to the mountpoint, and mountpoint is not a "sticky"
274 2) Even if 1) is solved the mount owner can change the behavior
277 i) It can slow down or indefinitely delay the execution of a
278 filesystem operation creating a DoS against the user or the
280 system file, and then accessing a file on the mount owner's
281 filesystem could be stopped, and thus causing the system
290 to access the filesystem, which could otherwise not be
291 monitored or manipulated by the mount owner. Since if the
292 mount owner can ptrace a process, it can do all of the above
293 without using a FUSE mount, the same criteria as used in
295 the filesystem or not.
297 Note that the ptrace check is not strictly necessary to
299 privilege to send signal to the process accessing the
305 If a sysadmin trusts the users enough, or can ensure through other
307 mounts, it can relax the last limitation with a "user_allow_other"
308 config option. If this config option is set, the mounting user can
309 add the "allow_other" mount option which disables the check for other
380 The solution for this is to allow the filesystem to be aborted.
386 the above, only the call back to the filesystem is not explicit,
413 Solution is basically the same as above.
415 An additional problem is that while the write buffer is being copied
416 to the request, the request must not be interrupted/aborted. This is
417 because the destination address of the copy may not be valid after the
420 This is solved with doing the copy atomically, and allowing abort
421 while the page(s) belonging to the write buffer are faulted with
422 get_user_pages(). The 'req->locked' flag indicates when the copy is