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path: root/fs/namei.c
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2013-09-17atomic_open: take care of EEXIST in no-open case with O_CREAT|O_EXCL in ↵Al Viro
fs/namei.c Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-16vfs: don't set FILE_CREATED before calling ->atomic_open()Miklos Szeredi
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: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-10Add missing unlocks to error paths of mountpoint_last.Dave Jones
Signed-off-by: Dave Jones <davej@fedoraproject.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-10... and fold the renamed __vfs_follow_link() into its only callerAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-10fs: remove vfs_follow_linkChristoph Hellwig
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: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-10Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile 3 (of many) from Al Viro: "Waiman's conversion of d_path() and bits related to it, kern_path_mountpoint(), several cleanups and fixes (exportfs one is -stable fodder, IMO). There definitely will be more... ;-/" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: split read_seqretry_or_unlock(), convert d_walk() to resulting primitives dcache: Translating dentry into pathname without taking rename_lock autofs4 - fix device ioctl mount lookup introduce kern_path_mountpoint() rename user_path_umountat() to user_path_mountpoint_at() take unlazy_walk() into umount_lookup_last() Kill indirect include of file.h from eventfd.h, use fdget() in cgroup.c prune_super(): sb->s_op is never NULL exportfs: don't assume that ->iterate() won't feed us too long entries afs: get rid of redundant ->d_name.len checks
2013-09-10vfs: make sure we don't have a stale root path if unlazy_walk() failsLinus Torvalds
When I moved the RCU walk termination into unlazy_walk(), I didn't copy quite all of it: for the successful RCU termination we properly add the necessary reference counts to our temporary copy of the root path, but for the failure case we need to make sure that any temporary root path information is cleared out (since it does _not_ have the proper reference counts from the RCU lookup). We could clean up this mess by just always dropping the temporary root information, but Al points out that that would mean that a single lookup through symlinks could see multiple different root entries if it races with another thread doing chroot. Not that I think we should really care (we had that before too, back before we had a copy of the root path in the nameidata). Al says he has a cunning plan. In the meantime, this is the minimal fix for the problem, even if it's not all that pretty. Reported-by: Mace Moneta <moneta.mace@gmail.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-08vfs: fix dentry RCU to refcounting possibly sleeping dput()Linus Torvalds
This is the fix that the last two commits indirectly led up to - making sure that we don't call dput() in a bad context on the dentries we've looked up in RCU mode after the sequence count validation fails. This basically expands d_rcu_to_refcount() into the callers, and then fixes the callers to delay the dput() in the failure case until _after_ we've dropped all locks and are no longer in an RCU-locked region. The case of 'complete_walk()' was trivial, since its failure case did the unlock_rcu_walk() directly after the call to d_rcu_to_refcount(), and as such that is just a pure expansion of the function with a trivial movement of the resulting dput() to after 'unlock_rcu_walk()'. In contrast, the unlazy_walk() case was much more complicated, because not only does convert two different dentries from RCU to be reference counted, but it used to not call unlock_rcu_walk() at all, and instead just returned an error and let the caller clean everything up in "terminate_walk()". Happily, one of the dentries in question (called "parent" inside unlazy_walk()) is the dentry of "nd->path", which terminate_walk() wants a refcount to anyway for the non-RCU case. So what the new and improved unlazy_walk() does is to first turn that dentry into a refcounted one, and once that is set up, the error cases can continue to use the terminate_walk() helper for cleanup, but for the non-RCU case. Which makes it possible to drop out of RCU mode if we actually hit the sequence number failure case. Acked-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-08introduce kern_path_mountpoint()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-08rename user_path_umountat() to user_path_mountpoint_at()Al Viro
... and move the extern from linux/namei.h to fs/internal.h, along with that of vfs_path_lookup(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-08take unlazy_walk() into umount_lookup_last()Al Viro
... and massage it a bit to reduce nesting Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-08vfs: use lockred "dead" flag to mark unrecoverably dead dentriesLinus Torvalds
This simplifies the RCU to refcounting code in particular. I was originally intending to leave this for later, but walking through all the dput() logic (see previous commit), I realized that the dput() "might_sleep()" check was misleadingly weak. And I removed it as misleading, both for performance profiling and for debugging. However, the might_sleep() debugging case is actually true: the final dput() can indeed sleep, if the inode of the dentry that you are releasing ends up sleeping at iput time (see dentry_iput()). So the problem with the might_sleep() in dput() wasn't that it wasn't true, it was that it wasn't actually testing and triggering on the interesting case. In particular, just about *any* dput() can indeed sleep, if you happen to race with another thread deleting the file in question, and you then lose the race to the be the last dput() for that file. But because it's a very rare race, the debugging code would never trigger it in practice. Why is this problematic? The new d_rcu_to_refcount() (see commit 15570086b590: "vfs: reimplement d_rcu_to_refcount() using lockref_get_or_lock()") does a dput() for the failure case, and it does it under the RCU lock. So potentially sleeping really is a bug. But there's no way I'm going to fix this with the previous complicated "lockref_get_or_lock()" interface. And rather than revert to the old and crufty nested dentry locking code (which did get this right by delaying the reference count updates until they were verified to be safe), let's make forward progress. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-05Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile 1 from Al Viro: "Unfortunately, this merge window it'll have a be a lot of small piles - my fault, actually, for not keeping #for-next in anything that would resemble a sane shape ;-/ This pile: assorted fixes (the first 3 are -stable fodder, IMO) and cleanups + %pd/%pD formats (dentry/file pathname, up to 4 last components) + several long-standing patches from various folks. There definitely will be a lot more (starting with Miklos' check_submount_and_drop() series)" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits) direct-io: Handle O_(D)SYNC AIO direct-io: Implement generic deferred AIO completions add formats for dentry/file pathnames kvm eventfd: switch to fdget powerpc kvm: use fdget switch fchmod() to fdget switch epoll_ctl() to fdget switch copy_module_from_fd() to fdget git simplify nilfs check for busy subtree ibmasmfs: don't bother passing superblock when not needed don't pass superblock to hypfs_{mkdir,create*} don't pass superblock to hypfs_diag_create_files don't pass superblock to hypfs_vm_create_files() oprofile: get rid of pointless forward declarations of struct super_block oprofilefs_create_...() do not need superblock argument oprofilefs_mkdir() doesn't need superblock argument don't bother with passing superblock to oprofile_create_stats_files() oprofile: don't bother with passing superblock to ->create_files() don't bother passing sb to oprofile_create_files() coh901318: don't open-code simple_read_from_buffer() ...
2013-09-03vfs: allow umount to handle mountpoints without revalidating themJeff Layton
Christopher reported a regression where he was unable to unmount a NFS filesystem where the root had gone stale. The problem is that d_revalidate handles the root of the filesystem differently from other dentries, but d_weak_revalidate does not. We could simply fix this by making d_weak_revalidate return success on IS_ROOT dentries, but there are cases where we do want to revalidate the root of the fs. A umount is really a special case. We generally aren't interested in anything but the dentry and vfsmount that's attached at that point. If the inode turns out to be stale we just don't care since the intent is to stop using it anyway. Try to handle this situation better by treating umount as a special case in the lookup code. Have it resolve the parent using normal means, and then do a lookup of the final dentry without revalidating it. In most cases, the final lookup will come out of the dcache, but the case where there's a trailing symlink or !LAST_NORM entry on the end complicates things a bit. Cc: Neil Brown <neilb@suse.de> Reported-by: Christopher T Vogan <cvogan@us.ibm.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-09-02vfs: reimplement d_rcu_to_refcount() using lockref_get_or_lock()Linus Torvalds
This moves __d_rcu_to_refcount() from <linux/dcache.h> into fs/namei.c and re-implements it using the lockref infrastructure instead. It also adds a lot of comments about what is actually going on, because turning a dentry that was looked up using RCU into a long-lived reference counted entry is one of the more subtle parts of the rcu walk. We also used to be _particularly_ subtle in unlazy_walk() where we re-validate both the dentry and its parent using the same sequence count. We used to do it by nesting the locks and then verifying the sequence count just once. That was silly, because nested locking is expensive, but the sequence count check is not. So this just re-validates the dentry and the parent separately, avoiding the nested locking, and making the lockref lookup possible. Acked-by: Waiman Long <waiman.long@hp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-28vfs: make the dentry cache use the lockref infrastructureWaiman Long
This just replaces the dentry count/lock combination with the lockref structure that contains both a count and a spinlock, and does the mechanical conversion to use the lockref infrastructure. There are no semantic changes here, it's purely syntactic. The reference lockref implementation uses the spinlock exactly the same way that the old dcache code did, and the bulk of this patch is just expanding the internal "d_count" use in the dcache code to use "d_lockref.count" instead. This is purely preparation for the real change to make the reference count updates be lockless during the 3.12 merge window. [ As with the previous commit, this is a rewritten version of a concept originally from Waiman, so credit goes to him, blame for any errors goes to me. Waiman's patch had some semantic differences for taking advantage of the lockless update in dget_parent(), while this patch is intentionally a pure search-and-replace change with no semantic changes. - Linus ] Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-28Revert "fs: Allow unprivileged linkat(..., AT_EMPTY_PATH) aka flink"Linus Torvalds
This reverts commit bb2314b47996491bbc5add73633905c3120b6268. It wasn't necessarily wrong per se, but we're still busily discussing the exact details of this all, so I'm going to revert it for now. It's true that you can already do flink() through /proc and that flink() isn't new. But as Brad Spengler points out, some secure environments do not mount proc, and flink adds a new interface that can avoid path lookup of the source for those kinds of environments. We may re-do this (and even mark it for stable backporting back in 3.11 and possibly earlier) once the whole discussion about the interface is done. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Brad Spengler <spender@grsecurity.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-05fs: Allow unprivileged linkat(..., AT_EMPTY_PATH) aka flinkAndy Lutomirski
Every now and then someone proposes a new flink syscall, and this spawns a long discussion of whether it would be a security problem. I think that this is missing the point: flink is *already* allowed without privilege as long as /proc is mounted -- it's called AT_SYMLINK_FOLLOW. Now that O_TMPFILE is here, the ability to create a file with O_TMPFILE, write it, and link it in is very convenient. The only problem is that it requires that /proc be mounted so that you can do: linkat(AT_FDCWD, "/proc/self/fd/<tmpfd>", dfd, path, AT_SYMLINK_NOFOLLOW) This sucks -- it's much nicer to do: linkat(tmpfd, "", dfd, path, AT_EMPTY_PATH) Let's allow it. If this turns out to be excessively scary, it we could instead require that the inode in question be I_LINKABLE, but this seems pointless given the /proc situation Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-13Safer ABI for O_TMPFILEAl Viro
[suggested by Rasmus Villemoes] make O_DIRECTORY | O_RDWR part of O_TMPFILE; that will fail on old kernels in a lot more cases than what I came up with. And make sure O_CREAT doesn't get there... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29Don't pass inode to ->d_hash() and ->d_compare()Linus Torvalds
Instances either don't look at it at all (the majority of cases) or only want it to find the superblock (which can be had as dentry->d_sb). A few cases that want more are actually safe with dentry->d_inode - the only precaution needed is the check that it hadn't been replaced with NULL by rmdir() or by overwriting rename(), which case should be simply treated as cache miss. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29allow the temp files created by open() to be linked toAl Viro
O_TMPFILE | O_CREAT => linkat() with AT_SYMLINK_FOLLOW and /proc/self/fd/<n> as oldpath (i.e. flink()) will create a link O_TMPFILE | O_CREAT | O_EXCL => ENOENT on attempt to link those guys Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29[O_TMPFILE] it's still short a few helpers, but infrastructure should be OK ↵Al Viro
now... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29allow build_open_flags() to return an errorAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29do_last(): fix missing checks for LAST_BIND caseAl Viro
/proc/self/cwd with O_CREAT should fail with EISDIR. /proc/self/exe, OTOH, should fail with ENOTDIR when opened with O_DIRECTORY. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-15use can_lookup() instead of direct checks of ->i_op->lookupAl Viro
a couple of places got missed back when Linus has introduced that one... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-05-11Merge git://git.infradead.org/users/eparis/auditLinus Torvalds
Pull audit changes from Eric Paris: "Al used to send pull requests every couple of years but he told me to just start pushing them to you directly. Our touching outside of core audit code is pretty straight forward. A couple of interface changes which hit net/. A simple argument bug calling audit functions in namei.c and the removal of some assembly branch prediction code on ppc" * git://git.infradead.org/users/eparis/audit: (31 commits) audit: fix message spacing printing auid Revert "audit: move kaudit thread start from auditd registration to kaudit init" audit: vfs: fix audit_inode call in O_CREAT case of do_last audit: Make testing for a valid loginuid explicit. audit: fix event coverage of AUDIT_ANOM_LINK audit: use spin_lock in audit_receive_msg to process tty logging audit: do not needlessly take a lock in tty_audit_exit audit: do not needlessly take a spinlock in copy_signal audit: add an option to control logging of passwords with pam_tty_audit audit: use spin_lock_irqsave/restore in audit tty code helper for some session id stuff audit: use a consistent audit helper to log lsm information audit: push loginuid and sessionid processing down audit: stop pushing loginid, uid, sessionid as arguments audit: remove the old depricated kernel interface audit: make validity checking generic audit: allow checking the type of audit message in the user filter audit: fix build break when AUDIT_DEBUG == 2 audit: remove duplicate export of audit_enabled Audit: do not print error when LSMs disabled ...
2013-05-07audit: vfs: fix audit_inode call in O_CREAT case of do_lastJeff Layton
Jiri reported a regression in auditing of open(..., O_CREAT) syscalls. In older kernels, creating a file with open(..., O_CREAT) created audit_name records that looked like this: type=PATH msg=audit(1360255720.628:64): item=1 name="/abc/foo" inode=138810 dev=fd:00 mode=0100640 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0 type=PATH msg=audit(1360255720.628:64): item=0 name="/abc/" inode=138635 dev=fd:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0 ...in recent kernels though, they look like this: type=PATH msg=audit(1360255402.886:12574): item=2 name=(null) inode=264599 dev=fd:00 mode=0100640 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0 type=PATH msg=audit(1360255402.886:12574): item=1 name=(null) inode=264598 dev=fd:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0 type=PATH msg=audit(1360255402.886:12574): item=0 name="/abc/foo" inode=264598 dev=fd:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0 Richard bisected to determine that the problems started with commit bfcec708, but the log messages have changed with some later audit-related patches. The problem is that this audit_inode call is passing in the parent of the dentry being opened, but audit_inode is being called with the parent flag false. This causes later audit_inode and audit_inode_child calls to match the wrong entry in the audit_names list. This patch simply sets the flag to properly indicate that this inode represents the parent. With this, the audit_names entries are back to looking like they did before. Cc: <stable@vger.kernel.org> # v3.7+ Reported-by: Jiri Jaburek <jjaburek@redhat.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Test By: Richard Guy Briggs <rbriggs@redhat.com> Signed-off-by: Eric Paris <eparis@redhat.com>
2013-03-08vfs: don't BUG_ON() if following a /proc fd pseudo-symlink results in a symlinkLinus Torvalds
It's "normal" - it can happen if the file descriptor you followed was opened with O_NOFOLLOW. Reported-by: Dave Jones <davej@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-01constify path_get/path_put and fs_struct.c stuffAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-26vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry opJeff Layton
The following set of operations on a NFS client and server will cause server# mkdir a client# cd a server# mv a a.bak client# sleep 30 # (or whatever the dir attrcache timeout is) client# stat . stat: cannot stat `.': Stale NFS file handle Obviously, we should not be getting an ESTALE error back there since the inode still exists on the server. The problem is that the lookup code will call d_revalidate on the dentry that "." refers to, because NFS has FS_REVAL_DOT set. nfs_lookup_revalidate will see that the parent directory has changed and will try to reverify the dentry by redoing a LOOKUP. That of course fails, so the lookup code returns ESTALE. The problem here is that d_revalidate is really a bad fit for this case. What we really want to know at this point is whether the inode is still good or not, but we don't really care what name it goes by or whether the dcache is still valid. Add a new d_op->d_weak_revalidate operation and have complete_walk call that instead of d_revalidate. The intent there is to allow for a "weaker" d_revalidate that just checks to see whether the inode is still good. This is also gives us an opportunity to kill off the FS_REVAL_DOT special casing. [AV: changed method name, added note in porting, fixed confusion re having it possibly called from RCU mode (it won't be)] Cc: NeilBrown <neilb@suse.de> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22lookup_slow: get rid of name argumentAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22lookup_fast: get rid of name argumentAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22get rid of name and type arguments of walk_component()Al Viro
... always can be found in nameidata now. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22link_path_walk(): move assignments to nd->last/nd->last_type upAl Viro
... and clean the main loop a bit Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22propagate error from get_empty_filp() to its callersAl Viro
Based on parts from Anatol's patch (the rest is the next commit). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22new helper: file_inode(file)Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: fix renameat to retry on ESTALE errorsJeff Layton
...as always, rename is the messiest of the bunch. We have to track whether to retry or not via a separate flag since the error handling is already quite complex. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: make do_unlinkat retry once on ESTALE errorsJeff Layton
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: make do_rmdir retry once on ESTALE errorsJeff Layton
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: add a flags argument to user_path_parentJeff Layton
...so we can pass in LOOKUP_REVAL. For now, nothing does yet. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: fix linkat to retry once on ESTALE errorsJeff Layton
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: fix symlinkat to retry on ESTALE errorsJeff Layton
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: fix mkdirat to retry once on an ESTALE errorJeff Layton
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: fix mknodat to retry on ESTALE errorsJeff Layton
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: turn is_dir argument to kern_path_create into a lookup_flags argJeff Layton
Where we can pass in LOOKUP_DIRECTORY or LOOKUP_REVAL. Any other flags passed in here are currently ignored. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: remove DCACHE_NEED_LOOKUPJeff Layton
The code that relied on that flag was ripped out of btrfs quite some time ago, and never added back. Josef indicated that he was going to take a different approach to the problem in btrfs, and that we could just eliminate this flag. Cc: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20path_init(): make -ENOTDIR failure exits consistentAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20vfs: remove unneeded permission check from path_initJeff Layton
When path_init is called with a valid dfd, that code checks permissions on the open directory fd and returns an error if the check fails. This permission check is redundant, however. Both callers of path_init immediately call link_path_walk afterward. The first thing that link_path_walk does for pathnames that do not consist only of slashes is to check for exec permissions at the starting point of the path walk. And this check in path_init() is on the path taken only when *name != '/' && *name != '\0'. In most cases, these checks are very quick, but when the dfd is for a file on a NFS mount with the actimeo=0, each permission check goes out onto the wire. The result is 2 identical ACCESS calls. Given that these codepaths are fairly "hot", I think it makes sense to eliminate the permission check in path_init and simply assume that the caller will eventually check the permissions before proceeding. Reported-by: Dave Wysochanski <dwysocha@redhat.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29lookup_one_len: don't accept . and ..Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-10-26VFS: don't do protected {sym,hard}links by defaultLinus Torvalds
In commit 800179c9b8a1 ("This adds symlink and hardlink restrictions to the Linux VFS"), the new link protections were enabled by default, in the hope that no actual application would care, despite it being technically against legacy UNIX (and documented POSIX) behavior. However, it does turn out to break some applications. It's rare, and it's unfortunate, but it's unacceptable to break existing systems, so we'll have to default to legacy behavior. In particular, it has broken the way AFD distributes files, see http://www.dwd.de/AFD/ along with some legacy scripts. Distributions can end up setting this at initrd time or in system scripts: if you have security problems due to link attacks during your early boot sequence, you have bigger problems than some kernel sysctl setting. Do: echo 1 > /proc/sys/fs/protected_symlinks echo 1 > /proc/sys/fs/protected_hardlinks to re-enable the link protections. Alternatively, we may at some point introduce a kernel config option that sets these kinds of "more secure but not traditional" behavioural options automatically. Reported-by: Nick Bowler <nbowler@elliptictech.com> Reported-by: Holger Kiehl <Holger.Kiehl@dwd.de> Cc: Kees Cook <keescook@chromium.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org # v3.6 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>