- 20 4月, 2014 1 次提交
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由 Al Viro 提交于
in non-lazy walk we need to be careful about dentry switching from negative to positive - both ->d_flags and ->d_inode are updated, and in some places we might see only one store. The cases where dentry has been obtained by dcache lookup with ->i_mutex held on parent are safe - ->d_lock and ->i_mutex provide all the barriers we need. However, there are several places where we run into trouble: * do_last() fetches ->d_inode, then checks ->d_flags and assumes that inode won't be NULL unless d_is_negative() is true. Race with e.g. creat() - we might have fetched the old value of ->d_inode (still NULL) and new value of ->d_flags (already not DCACHE_MISS_TYPE). Lin Ming has observed and reported the resulting oops. * a bunch of places checks ->d_inode for being non-NULL, then checks ->d_flags for "is it a symlink". Race with symlink(2) in case if our CPU sees ->d_inode update first - we see non-NULL there, but ->d_flags still contains DCACHE_MISS_TYPE instead of DCACHE_SYMLINK_TYPE. Result: false negative on "should we follow link here?", with subsequent unpleasantness. Cc: stable@vger.kernel.org # 3.13 and 3.14 need that one Reported-and-tested-by: NLin Ming <minggr@gmail.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 02 4月, 2014 3 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 01 4月, 2014 7 次提交
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由 Miklos Szeredi 提交于
If flags contain RENAME_EXCHANGE then exchange source and destination files. There's no restriction on the type of the files; e.g. a directory can be exchanged with a symlink. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJan Kara <jack@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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由 Miklos Szeredi 提交于
Add flags to security_path_rename() and security_inode_rename() hooks. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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由 Miklos Szeredi 提交于
If this flag is specified and the target of the rename exists then the rename syscall fails with EEXIST. The VFS does the existence checking, so it is trivial to enable for most local filesystems. This patch only enables it in ext4. For network filesystems the VFS check is not enough as there may be a race between a remote create and the rename, so these filesystems need to handle this flag in their ->rename() implementations to ensure atomicity. Andy writes about why this is useful: "The trivial answer: to eliminate the race condition from 'mv -i'. Another answer: there's a common pattern to atomically create a file with contents: open a temporary file, write to it, optionally fsync it, close it, then link(2) it to the final name, then unlink the temporary file. The reason to use link(2) is because it won't silently clobber the destination. This is annoying: - It requires an extra system call that shouldn't be necessary. - It doesn't work on (IMO sensible) filesystems that don't support hard links (e.g. vfat). - It's not atomic -- there's an intermediate state where both files exist. - It's ugly. The new rename flag will make this totally sensible. To be fair, on new enough kernels, you can also use O_TMPFILE and linkat to achieve the same thing even more cleanly." Suggested-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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由 Miklos Szeredi 提交于
Add new renameat2 syscall, which is the same as renameat with an added flags argument. Pass flags to vfs_rename() and to i_op->rename() as well. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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由 Miklos Szeredi 提交于
There's actually very little difference between vfs_rename_dir() and vfs_rename_other() so move both inline into vfs_rename() which still stays reasonably readable. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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由 Miklos Szeredi 提交于
Move the d_move() in vfs_rename_dir() up, similarly to how it's done in vfs_rename_other(). The next patch will consolidate these two functions and this is the only structural difference between them. I'm not sure if doing the d_move() after the dput is even valid. But there may be a logical explanation for that. But moving the d_move() before the dput() (and the mutex_unlock()) should definitely not hurt. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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由 Miklos Szeredi 提交于
Add d_is_dir(dentry) helper which is analogous to S_ISDIR(). To avoid confusion, rename d_is_directory() to d_can_lookup(). Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Reviewed-by: NJ. Bruce Fields <bfields@redhat.com>
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- 31 3月, 2014 1 次提交
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由 Jeff Layton 提交于
As Trond pointed out, you can currently deadlock yourself by setting a file-private lock on a file that requires mandatory locking and then trying to do I/O on it. Avoid this problem by plumbing some knowledge of file-private locks into the mandatory locking code. In order to do this, we must pass down information about the struct file that's being used to locks_verify_locked. Reported-by: NTrond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: NJeff Layton <jlayton@redhat.com> Acked-by: NJ. Bruce Fields <bfields@redhat.com>
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- 23 3月, 2014 1 次提交
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由 Al Viro 提交于
We can get false negative from __lookup_mnt() if an unrelated vfsmount gets moved. In that case legitimize_mnt() is guaranteed to fail, and we will fall back to non-RCU walk... unless we end up running into a hard error on a filesystem object we wouldn't have reached if not for that false negative. IOW, delaying that check until the end of pathname resolution is wrong - we should recheck right after we attempt to cross the mountpoint. We don't need to recheck unless we see d_mountpoint() being true - in that case even if we have just raced with mount/umount, we can simply go on as if we'd come at the moment when the sucker wasn't a mountpoint; if we run into a hard error as the result, it was a legitimate outcome. __lookup_mnt() returning NULL is different in that respect, since it might've happened due to operation on completely unrelated mountpoint. Cc: stable@vger.kernel.org Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 10 3月, 2014 1 次提交
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由 Linus Torvalds 提交于
Our write() system call has always been atomic in the sense that you get the expected thread-safe contiguous write, but we haven't actually guaranteed that concurrent writes are serialized wrt f_pos accesses, so threads (or processes) that share a file descriptor and use "write()" concurrently would quite likely overwrite each others data. This violates POSIX.1-2008/SUSv4 Section XSI 2.9.7 that says: "2.9.7 Thread Interactions with Regular File Operations All of the following functions shall be atomic with respect to each other in the effects specified in POSIX.1-2008 when they operate on regular files or symbolic links: [...]" and one of the effects is the file position update. This unprotected file position behavior is not new behavior, and nobody has ever cared. Until now. Yongzhi Pan reported unexpected behavior to Michael Kerrisk that was due to this. This resolves the issue with a f_pos-specific lock that is taken by read/write/lseek on file descriptors that may be shared across threads or processes. Reported-by: NYongzhi Pan <panyongzhi@gmail.com> Reported-by: NMichael Kerrisk <mtk.manpages@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 06 2月, 2014 1 次提交
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由 Linus Torvalds 提交于
This changes 'do_execve()' to get the executable name as a 'struct filename', and to free it when it is done. This is what the normal users want, and it simplifies and streamlines their error handling. The controlled lifetime of the executable name also fixes a use-after-free problem with the trace_sched_process_exec tracepoint: the lifetime of the passed-in string for kernel users was not at all obvious, and the user-mode helper code used UMH_WAIT_EXEC to serialize the pathname allocation lifetime with the execve() having finished, which in turn meant that the trace point that happened after mm_release() of the old process VM ended up using already free'd memory. To solve the kernel string lifetime issue, this simply introduces "getname_kernel()" that works like the normal user-space getname() function, except with the source coming from kernel memory. As Oleg points out, this also means that we could drop the tcomm[] array from 'struct linux_binprm', since the pathname lifetime now covers setup_new_exec(). That would be a separate cleanup. Reported-by: NIgor Zhbanov <i.zhbanov@samsung.com> Tested-by: NSteven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 01 2月, 2014 2 次提交
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由 Oleg Drokin 提交于
Recent changes to retry on ESTALE in linkat (commit 442e31ca) introduced a mountpoint reference leak and a small memory leak in case a filesystem link operation returns ESTALE which is pretty normal for distributed filesystems like lustre, nfs and so on. Free old_path in such a case. [AV: there was another missing path_put() nearby - on the previous goto retry] Signed-off-by: NOleg Drokin: <green@linuxhacker.ru> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Jeff Layton 提交于
Leaving getname() exported when putname() isn't is a bad idea. Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 26 1月, 2014 1 次提交
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由 Christoph Hellwig 提交于
Factor out the code to get an ACL either from the inode or disk from check_acl, so that it can be used elsewhere later on. Signed-off-by: NChristoph Hellwig <hch@lst.de> Reviewed-by: NJan Kara <jack@suse.cz> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 13 12月, 2013 1 次提交
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由 Will Deacon 提交于
When explicitly hashing the end of a string with the word-at-a-time interface, we have to be careful which end of the word we pick up. On big-endian CPUs, the upper-bits will contain the data we're after, so ensure we generate our masks accordingly (and avoid hashing whatever random junk may have been sitting after the string). This patch adds a new dcache helper, bytemask_from_count, which creates a mask appropriate for the CPU endianness. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 29 11月, 2013 1 次提交
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由 Al Viro 提交于
Failure to grab reference to parent dentry should go through the same cleanup as nd->seq mismatch. As it is, we might end up with caller thinking it needs to path_put() nd->root, with obvious nasty results once we'd hit that bug enough times to drive the refcount of root dentry all the way to zero... Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 09 11月, 2013 10 次提交
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由 J. Bruce Fields 提交于
Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Dustin Kirkland <dustin.kirkland@gazzang.com> Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 J. Bruce Fields 提交于
Cc: David Howells <dhowells@redhat.com> Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 J. Bruce Fields 提交于
We'll need the same logic for rename and link. Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 J. Bruce Fields 提交于
We need to break delegations on any operation that changes the set of links pointing to an inode. Start with unlink. Such operations also hold the i_mutex on a parent directory. Breaking a delegation may require waiting for a timeout (by default 90 seconds) in the case of a unresponsive NFS client. To avoid blocking all directory operations, we therefore drop locks before waiting for the delegation. The logic then looks like: acquire locks ... test for delegation; if found: take reference on inode release locks wait for delegation break drop reference on inode retry It is possible this could never terminate. (Even if we take precautions to prevent another delegation being acquired on the same inode, we could get a different inode on each retry.) But this seems very unlikely. The initial test for a delegation happens after the lock on the target inode is acquired, but the directory inode may have been acquired further up the call stack. We therefore add a "struct inode **" argument to any intervening functions, which we use to pass the inode back up to the caller in the case it needs a delegation synchronously broken. Cc: David Howells <dhowells@redhat.com> Cc: Tyler Hicks <tyhicks@canonical.com> Cc: Dustin Kirkland <dustin.kirkland@gazzang.com> Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 J. Bruce Fields 提交于
We'll be using dentry->d_inode in one more place. Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 J. Bruce Fields 提交于
A read delegation is used by NFSv4 as a guarantee that a client can perform local read opens without informing the server. The open operation takes the last component of the pathname as an argument, thus is also a lookup operation, and giving the client the above guarantee means informing the client before we allow anything that would change the set of names pointing to the inode. Therefore, we need to break delegations on rename, link, and unlink. We also need to prevent new delegations from being acquired while one of these operations is in progress. We could add some completely new locking for that purpose, but it's simpler to use the i_mutex, since that's already taken by all the operations we care about. The single exception is rename. So, modify rename to take the i_mutex on the file that is being renamed. Also fix up lockdep and Documentation/filesystems/directory-locking to reflect the change. Acked-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 J. Bruce Fields 提交于
The DCACHE_NEED_LOOKUP case referred to here was removed with 39e3c955 "vfs: remove DCACHE_NEED_LOOKUP". There are only four real_lookup() callers and all of them pass in an unhashed dentry just returned from d_alloc. Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 David Howells 提交于
Put a type field into struct dentry::d_flags to indicate if the dentry is one of the following types that relate particularly to pathwalk: Miss (negative dentry) Directory "Automount" directory (defective - no i_op->lookup()) Symlink Other (regular, socket, fifo, device) The type field is set to one of the first five types on a dentry by calls to __d_instantiate() and d_obtain_alias() from information in the inode (if one is given). The type is cleared by dentry_unlink_inode() when it reconstitutes an existing dentry as a negative dentry. Accessors provided are: d_set_type(dentry, type) d_is_directory(dentry) d_is_autodir(dentry) d_is_symlink(dentry) d_is_file(dentry) d_is_negative(dentry) d_is_positive(dentry) A bunch of checks in pathname resolution switched to those. Signed-off-by: NDavid Howells <dhowells@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
those have become aliases for rcu_read_{lock,unlock}() Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
* RCU-delayed freeing of vfsmounts * vfsmount_lock replaced with a seqlock (mount_lock) * sequence number from mount_lock is stored in nameidata->m_seq and used when we exit RCU mode * new vfsmount flag - MNT_SYNC_UMOUNT. Set by umount_tree() when its caller knows that vfsmount will have no surviving references. * synchronize_rcu() done between unlocking namespace_sem in namespace_unlock() and doing pending mntput(). * new helper: legitimize_mnt(mnt, seq). Checks the mount_lock sequence number against seq, then grabs reference to mnt. Then it rechecks mount_lock again to close the race and either returns success or drops the reference it has acquired. The subtle point is that in case of MNT_SYNC_UMOUNT we can simply decrement the refcount and sod off - aforementioned synchronize_rcu() makes sure that final mntput() won't come until we leave RCU mode. We need that, since we don't want to end up with some lazy pathwalk racing with umount() and stealing the final mntput() from it - caller of umount() may expect it to return only once the fs is shut down and we don't want to break that. In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do full-blown mntput() in case of mount_lock sequence number mismatch happening just as we'd grabbed the reference, but in those cases we won't be stealing the final mntput() from anything that would care. * mntput_no_expire() doesn't lock anything on the fast path now. Incidentally, SMP and UP cases are handled the same way - no ifdefs there. * normal pathname resolution does *not* do any writes to mount_lock. It does, of course, bump the refcounts of vfsmount and dentry in the very end, but that's it. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 06 11月, 2013 1 次提交
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由 Jeff Layton 提交于
Historically, when a syscall that creates a dentry fails, you get an audit record that looks something like this (when trying to create a file named "new" in "/tmp/tmp.SxiLnCcv63"): type=PATH msg=audit(1366128956.279:965): item=0 name="/tmp/tmp.SxiLnCcv63/new" inode=2138308 dev=fd:02 mode=040700 ouid=0 ogid=0 rdev=00:00 obj=staff_u:object_r:user_tmp_t:s15:c0.c1023 This record makes no sense since it's associating the inode information for "/tmp/tmp.SxiLnCcv63" with the path "/tmp/tmp.SxiLnCcv63/new". The recent patch I posted to fix the audit_inode call in do_last fixes this, by making it look more like this: type=PATH msg=audit(1366128765.989:13875): item=0 name="/tmp/tmp.DJ1O8V3e4f/" inode=141 dev=fd:02 mode=040700 ouid=0 ogid=0 rdev=00:00 obj=staff_u:object_r:user_tmp_t:s15:c0.c1023 While this is more correct, if the creation of the file fails, then we have no record of the filename that the user tried to create. This patch adds a call to audit_inode_child to may_create. This creates an AUDIT_TYPE_CHILD_CREATE record that will sit in place until the create succeeds. When and if the create does succeed, then this record will be updated with the correct inode info from the create. This fixes what was broken in commit bfcec708. Commit 79f6530c should also be backported to stable v3.7+. Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NRichard Guy Briggs <rgb@redhat.com> Signed-off-by: NEric Paris <eparis@redhat.com>
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- 25 10月, 2013 1 次提交
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由 Al Viro 提交于
Instead of passing the direction as argument (and checking it on every step through the hash chain), just have separate __lookup_mnt() and __lookup_mnt_last(). And use the standard iterators... Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 22 10月, 2013 1 次提交
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由 Randy Dunlap 提交于
Add @path parameter to fix kernel-doc warning. Also fix a spello/typo. Warning(fs/namei.c:2304): No description found for parameter 'path' Signed-off-by: NRandy Dunlap <rdunlap@infradead.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 18 9月, 2013 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 17 9月, 2013 1 次提交
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由 Miklos Szeredi 提交于
If O_CREAT|O_EXCL are passed to open, then we know that either - the file is successfully created, or - the operation fails in some way. So previously we set FILE_CREATED before calling ->atomic_open() so the filesystem doesn't have to. This, however, led to bugs in the implementation that went unnoticed when the filesystem didn't check for existence, yet returned success. To prevent this kind of bug, require filesystems to always explicitly set FILE_CREATED on O_CREAT|O_EXCL and verify this in the VFS. Also added a couple more verifications for the result of atomic_open(): - Warn if filesystem set FILE_CREATED despite the lack of O_CREAT. - Warn if filesystem set FILE_CREATED but gave a negative dentry. Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 11 9月, 2013 5 次提交
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由 Dave Jones 提交于
Signed-off-by: NDave Jones <davej@fedoraproject.org> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Christoph Hellwig 提交于
For a long time no filesystem has been using vfs_follow_link, and as seen by recent filesystem submissions any new use is accidental as well. Remove vfs_follow_link, document the replacement in Documentation/filesystems/porting and also rename __vfs_follow_link to match its only caller better. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Dave Jones 提交于
Signed-off-by: NDave Jones <davej@fedoraproject.org> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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