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* [PATCH] FUSE: don't allow restarting of system callsMiklos Szeredi2005-09-091-11/+1
| | | | | | | | | | | | | | | | | | | | | This patch removes ability to interrupt and restart operations while there hasn't been any side-effect. The reason: applications. There are some apps it seems that generate signals at a fast rate. This means, that if the operation cannot make enough progress between two signals, it will be restarted for ever. This bug actually manifested itself with 'krusader' trying to open a file for writing under sshfs. Thanks to Eduard Czimbalmos for the report. The problem can be solved just by making open() uninterruptible, because in this case it was the truncate operation that slowed down the progress. But it's better to solve this by simply not allowing interrupts at all (except SIGKILL), because applications don't expect file operations to be interruptible anyway. As an added bonus the code is simplified somewhat. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE: add fsync operation for directoriesMiklos Szeredi2005-09-091-0/+9
| | | | | | | | | | This patch adds a new FSYNCDIR request, which is sent when fsync is called on directories. This operation is available in libfuse 2.3-pre1 or greater. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] fuse: more flexible cachingMiklos Szeredi2005-09-091-6/+0
| | | | | | | | | | | Make data caching behavior selectable on a per-open basis instead of per-mount. Compatibility for the old mount options 'kernel_cache' and 'direct_io' is retained in the userspace library (version 2.4.0-pre1 or later). Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] fuse: transfer readdir data through deviceMiklos Szeredi2005-09-091-5/+17
| | | | | | | | | | | | | | | | | This patch removes a long lasting "hack" in FUSE, which used a separate channel (a file descriptor refering to a disk-file) to transfer directory contents from userspace to the kernel. The patch adds three new operations (OPENDIR, READDIR, RELEASEDIR), which have semantics and implementation exactly maching the respective file operations (OPEN, READ, RELEASE). This simplifies the directory reading code. Also disk space is not necessary, which can be important in embedded systems. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - direct I/OMiklos Szeredi2005-09-091-0/+6
| | | | | | | | | | | | | This patch adds support for the "direct_io" mount option of FUSE. When this mount option is specified, the page cache is bypassed for read and write operations. This is useful for example, if the filesystem doesn't know the size of files before reading them, or when any kind of caching is harmful. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE: tighten check for processes allowed accessMiklos Szeredi2005-09-091-0/+3
| | | | | | | | | | | | | | | | | This patch tightens the check for allowing processes to access non-privileged mounts. The rational is that the filesystem implementation can control the behavior or get otherwise unavailable information of the filesystem user. If the filesystem user process has the same uid, gid, and is not suid or sgid application, then access is safe. Otherwise access is not allowed unless the "allow_other" mount option is given (for which policy is controlled by the userspace mount utility). Thanks to everyone linux-fsdevel, especially Martin Mares who helped uncover problems with the previous approach. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - readpages operationMiklos Szeredi2005-09-091-0/+3
| | | | | | | | | | | | This patch adds readpages support to FUSE. With the help of the readpages() operation multiple reads are bundled together and sent as a single request to userspace. This can improve reading performace. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - extended attribute operationsMiklos Szeredi2005-09-091-0/+12
| | | | | | | | | | | | | | | This patch adds the extended attribute operations to FUSE. The following operations are added: o getxattr o setxattr o listxattr o removexattr Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - mount optionsMiklos Szeredi2005-09-091-5/+40
| | | | | | | | | | | | | | | This patch adds miscellaneous mount options to the FUSE filesystem. The following mount options are added: o default_permissions: check permissions with generic_permission() o allow_other: allow other users to access files o allow_root: allow root to access files o kernel_cache: don't invalidate page cache on open Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - file operationsMiklos Szeredi2005-09-091-0/+21
| | | | | | | | | | | | | | | | | This patch adds the file operations of FUSE. The following operations are added: o open o flush o release o fsync o readpage o commit_write Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - read-write operationsMiklos Szeredi2005-09-091-2/+5
| | | | | | | | | | | | | | | | | | | | This patch adds the write filesystem operations of FUSE. The following operations are added: o setattr o symlink o mknod o mkdir o create o unlink o rmdir o rename o link Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - read-only operationsMiklos Szeredi2005-09-091-0/+51
| | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds the read-only filesystem operations of FUSE. This contains the following files: o dir.c - directory, symlink and file-inode operations The following operations are added: o lookup o getattr o readlink o follow_link o directory open o readdir o directory release o permission o dentry revalidate o statfs Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - device functionsMiklos Szeredi2005-09-091-0/+223
| | | | | | | | | | | | | | | | This adds the FUSE device handling functions. This contains the following files: o dev.c - fuse device operations (read, write, release, poll) - registers misc device - support for sending requests to userspace Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] FUSE - coreMiklos Szeredi2005-09-091-0/+89
This patch adds FUSE core. This contains the following files: o inode.c - superblock operations (alloc_inode, destroy_inode, read_inode, clear_inode, put_super, show_options) - registers FUSE filesystem o fuse_i.h - private header file Requirements ============ The most important difference between orinary filesystems and FUSE is the fact, that the filesystem data/metadata is provided by a userspace process run with the privileges of the mount "owner" instead of the kernel, or some remote entity usually running with elevated privileges. The security implication of this is that a non-privileged user must not be able to use this capability to compromise the system. Obvious requirements arising from this are: - mount owner should not be able to get elevated privileges with the help of the mounted filesystem - mount owner should not be able to induce undesired behavior in other users' or the super user's processes - mount owner should not get illegitimate access to information from other users' and the super user's processes These are currently ensured with the following constraints: 1) mount is only allowed to directory or file which the mount owner can modify without limitation (write access + no sticky bit for directories) 2) nosuid,nodev mount options are forced 3) any process running with fsuid different from the owner is denied all access to the filesystem 1) and 2) are ensured by the "fusermount" mount utility which is a setuid root application doing the actual mount operation. 3) is ensured by a check in the permission() method in kernel I started thinking about doing 3) in a different way because Christoph H. made a big deal out of it, saying that FUSE is unacceptable into mainline in this form. The suggested use of private namespaces would be OK, but in their current form have many limitations that make their use impractical (as discussed in this thread). Suggested improvements that would address these limitations: - implement shared subtrees - allow a process to join an existing namespace (make namespaces first-class objects) - implement the namespace creation/joining in a PAM module With all that in place the check of owner against current->fsuid may be removed from the FUSE kernel module, without compromising the security requirements. Suid programs still interesting questions, since they get access even to the private namespace causing some information leak (exact order/timing of filesystem operations performed), giving some ptrace-like capabilities to unprivileged users. BTW this problem is not strictly limited to the namespace approach, since suid programs setting fsuid and accessing users' files will succeed with the current approach too. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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