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path: root/fs/locks.c
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2014-03-31locks: make locks_mandatory_area check for file-private locksJeff Layton1-2/+13
Allow locks_mandatory_area() to handle file-private locks correctly. If there is a file-private lock set on an open file and we're doing I/O via the same, then that should not cause anything to block. Handle this by first doing a non-blocking FL_ACCESS check for a file-private lock, and then fall back to checking for a classic POSIX lock (and possibly blocking). Note that this approach is subject to the same races that have always plagued mandatory locking on Linux. Reported-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: fix locks_mandatory_locked to respect file-private locksJeff Layton1-3/+4
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: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@redhat.com>
2014-03-31locks: require that flock->l_pid be set to 0 for file-private locksJeff Layton1-0/+24
Neil Brown suggested potentially overloading the l_pid value as a "lock context" field for file-private locks. While I don't think we will probably want to do that here, it's probably a good idea to ensure that in the future we could extend this API without breaking existing callers. Typically the l_pid value is ignored for incoming struct flock arguments, serving mainly as a place to return the pid of the owner if there is a conflicting lock. For file-private locks, require that it currently be set to 0 and return EINVAL if it isn't. If we eventually want to make a non-zero l_pid mean something, then this will help ensure that we don't break legacy programs that are using file-private locks. Cc: Neil Brown <neilb@suse.de> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: add new fcntl cmd values for handling file private locksJeff Layton1-4/+50
Due to some unfortunate history, POSIX locks have very strange and unhelpful semantics. The thing that usually catches people by surprise is that they are dropped whenever the process closes any file descriptor associated with the inode. This is extremely problematic for people developing file servers that need to implement byte-range locks. Developers often need a "lock management" facility to ensure that file descriptors are not closed until all of the locks associated with the inode are finished. Additionally, "classic" POSIX locks are owned by the process. Locks taken between threads within the same process won't conflict with one another, which renders them useless for synchronization between threads. This patchset adds a new type of lock that attempts to address these issues. These locks conflict with classic POSIX read/write locks, but have semantics that are more like BSD locks with respect to inheritance and behavior on close. This is implemented primarily by changing how fl_owner field is set for these locks. Instead of having them owned by the files_struct of the process, they are instead owned by the filp on which they were acquired. Thus, they are inherited across fork() and are only released when the last reference to a filp is put. These new semantics prevent them from being merged with classic POSIX locks, even if they are acquired by the same process. These locks will also conflict with classic POSIX locks even if they are acquired by the same process or on the same file descriptor. The new locks are managed using a new set of cmd values to the fcntl() syscall. The initial implementation of this converts these values to "classic" cmd values at a fairly high level, and the details are not exposed to the underlying filesystem. We may eventually want to push this handing out to the lower filesystem code but for now I don't see any need for it. Also, note that with this implementation the new cmd values are only available via fcntl64() on 32-bit arches. There's little need to add support for legacy apps on a new interface like this. Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: skip deadlock detection on FL_FILE_PVT locksJeff Layton1-2/+17
It's not really feasible to do deadlock detection with FL_FILE_PVT locks since they aren't owned by a single task, per-se. Deadlock detection also tends to be rather expensive so just skip it for these sorts of locks. Also, add a FIXME comment about adding more limited deadlock detection that just applies to ro -> rw upgrades, per Andy's request. Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: pass the cmd value to fcntl_getlk/getlk64Jeff Layton1-2/+2
Once we introduce file private locks, we'll need to know what cmd value was used, as that affects the ownership and whether a conflict would arise. Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: report l_pid as -1 for FL_FILE_PVT locksJeff Layton1-2/+2
FL_FILE_PVT locks are no longer tied to a particular pid, and are instead inheritable by child processes. Report a l_pid of '-1' for these sorts of locks since the pid is somewhat meaningless for them. This precedent comes from FreeBSD. There, POSIX and flock() locks can conflict with one another. If fcntl(F_GETLK, ...) returns a lock set with flock() then the l_pid member cannot be a process ID because the lock is not held by a process as such. Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: make /proc/locks show IS_FILE_PVT locks as type "FLPVT"Jeff Layton1-2/+9
In a later patch, we'll be adding a new type of lock that's owned by the struct file instead of the files_struct. Those sorts of locks will be flagged with a new FL_FILE_PVT flag. Report these types of locks as "FLPVT" in /proc/locks to distinguish them from "classic" POSIX locks. Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: rename locks_remove_flock to locks_remove_fileJeff Layton1-1/+1
This function currently removes leases in addition to flock locks and in a later patch we'll have it deal with file-private locks too. Rename it to locks_remove_file to indicate that it removes locks that are associated with a particular struct file, and not just flock locks. Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: consolidate checks for compatible filp->f_mode values in setlk handlersJeff Layton1-34/+12
Move this check into flock64_to_posix_lock instead of duplicating it in two places. This also fixes a minor wart in the code where we continue referring to the struct flock after converting it to struct file_lock. Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: fix posix lock range overflow handlingJ. Bruce Fields1-68/+32
In the 32-bit case fcntl assigns the 64-bit f_pos and i_size to a 32-bit off_t. The existing range checks also seem to depend on signed arithmetic wrapping when it overflows. In practice maybe that works, but we can be more careful. That also allows us to make a more reliable distinction between -EINVAL and -EOVERFLOW. Note that in the 32-bit case SEEK_CUR or SEEK_END might allow the caller to set a lock with starting point no longer representable as a 32-bit value. We could return -EOVERFLOW in such cases, but the locks code is capable of handling such ranges, so we choose to be lenient here. The only problem is that subsequent GETLK calls on such a lock will fail with EOVERFLOW. While we're here, do some cleanup including consolidating code for the flock and flock64 cases. Signed-off-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: eliminate BUG() call when there's an unexpected lock on file closeJeff Layton1-6/+18
A leftover lock on the list is surely a sign of a problem of some sort, but it's not necessarily a reason to panic the box. Instead, just log a warning with some info about the lock, and then delete it like we would any other lock. In the event that the filesystem declares a ->lock f_op, we may end up leaking something, but that's generally preferable to an immediate panic. Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: add __acquires and __releases annotations to locks_start and locks_stopJeff Layton1-0/+2
...to make sparse happy. Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: remove "inline" qualifier from fl_link manipulation functionsJeff Layton1-8/+4
It's best to let the compiler decide that. Acked-by: J. Bruce Fields <bfields@fieldses.org> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: clean up comment typoJeff Layton1-1/+1
Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Jeff Layton <jlayton@redhat.com>
2014-03-31locks: close potential race between setlease and openJeff Layton1-13/+62
As Al Viro points out, there is an unlikely, but possible race between opening a file and setting a lease on it. generic_add_lease is done with the i_lock held, but the inode->i_flock check in break_lease is lockless. It's possible for another task doing an open to do the entire pathwalk and call break_lease between the point where generic_add_lease checks for a conflicting open and adds the lease to the list. If this occurs, we can end up with a lease set on the file with a conflicting open. To guard against that, check again for a conflicting open after adding the lease to the i_flock list. If the above race occurs, then we can simply unwind the lease setting and return -EAGAIN. Because we take dentry references and acquire write access on the file before calling break_lease, we know that if the i_flock list is empty when the open caller goes to check it then the necessary refcounts have already been incremented. Thus the additional check for a conflicting open will see that there is one and the setlease call will fail. Cc: Bruce Fields <bfields@fieldses.org> Cc: David Howells <dhowells@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@fieldses.org>
2013-11-13locks: missing unlock on error in generic_add_lease()Dan Carpenter1-0/+1
We should unlock here before returning. Fixes: df4e8d2c1d2b ('locks: implement delegations') Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09locks: implement delegationsJ. Bruce Fields1-10/+45
Implement NFSv4 delegations at the vfs level using the new FL_DELEG lock type. Note nfsd is the only delegation user and is only using read delegations. Warn on any attempt to set a write delegation for now. We'll come back to that case later. Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09locks: introduce new FL_DELEG lock flagJ. Bruce Fields1-1/+1
For now FL_DELEG is just a synonym for FL_LEASE. So this patch doesn't change behavior. Next we'll modify break_lease to treat FL_DELEG leases differently, to account for the fact that NFSv4 delegations should be broken in more situations than Windows oplocks. Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-10-24file->f_op is never NULL...Al Viro1-6/+6
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-08locks: move file_lock_list to a set of percpu hlist_heads and convert ↵Jeff Layton1-20/+49
file_lock_lock to an lglock The file_lock_list is only used for /proc/locks. The vastly common case is for locks to be put onto the list and come off again, without ever being traversed. Help optimize for this use-case by moving to percpu hlist_head-s. At the same time, we can make the locking less contentious by moving to an lglock. When iterating over the lists for /proc/locks, we must take the global lock and then iterate over each CPU's list in turn. This change necessitates a new fl_link_cpu field to keep track of which CPU the entry is on. On x86_64 at least, this field is placed within an existing hole in the struct to avoid growing the size. Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-07-05helper for reading ->d_countAl Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: give the blocked_hash its own spinlockJeff Layton1-19/+22
There's no reason we have to protect the blocked_hash and file_lock_list with the same spinlock. With the tests I have, breaking it in two gives a barely measurable performance benefit, but it seems reasonable to make this locking as granular as possible. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: add a new "lm_owner_key" lock operationJeff Layton1-2/+10
Currently, the hashing that the locking code uses to add these values to the blocked_hash is simply calculated using fl_owner field. That's valid in most cases except for server-side lockd, which validates the owner of a lock based on fl_owner and fl_pid. In the case where you have a small number of NFS clients doing a lot of locking between different processes, you could end up with all the blocked requests sitting in a very small number of hash buckets. Add a new lm_owner_key operation to the lock_manager_operations that will generate an unsigned long to use as the key in the hashtable. That function is only implemented for server-side lockd, and simply XORs the fl_owner and fl_pid. Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: turn the blocked_list into a hashtableJeff Layton1-8/+17
Break up the blocked_list into a hashtable, using the fl_owner as a key. This speeds up searching the hash chains, which is especially significant for deadlock detection. Note that the initial implementation assumes that hashing on fl_owner is sufficient. In most cases it should be, with the notable exception being server-side lockd, which compares ownership using a tuple of the nlm_host and the pid sent in the lock request. So, this may degrade to a single hash bucket when you only have a single NFS client. That will be addressed in a later patch. The careful observer may note that this patch leaves the file_lock_list alone. There's much less of a case for turning the file_lock_list into a hashtable. The only user of that list is the code that generates /proc/locks, and it always walks the entire list. Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: convert fl_link to a hlist_nodeJeff Layton1-12/+12
Testing has shown that iterating over the blocked_list for deadlock detection turns out to be a bottleneck. In order to alleviate that, begin the process of turning it into a hashtable. We start by turning the fl_link into a hlist_node and the global lists into hlists. A later patch will do the conversion of the blocked_list to a hashtable. Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: avoid taking global lock if possible when waking up blocked waitersJeff Layton1-1/+14
Since we always hold the i_lock when inserting a new waiter onto the fl_block list, we can avoid taking the global lock at all if we find that it's empty when we go to wake up blocked waiters. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: protect most of the file_lock handling with i_lockJeff Layton1-60/+104
Having a global lock that protects all of this code is a clear scalability problem. Instead of doing that, move most of the code to be protected by the i_lock instead. The exceptions are the global lists that the ->fl_link sits on, and the ->fl_block list. ->fl_link is what connects these structures to the global lists, so we must ensure that we hold those locks when iterating over or updating these lists. Furthermore, sound deadlock detection requires that we hold the blocked_list state steady while checking for loops. We also must ensure that the search and update to the list are atomic. For the checking and insertion side of the blocked_list, push the acquisition of the global lock into __posix_lock_file and ensure that checking and update of the blocked_list is done without dropping the lock in between. On the removal side, when waking up blocked lock waiters, take the global lock before walking the blocked list and dequeue the waiters from the global list prior to removal from the fl_block list. With this, deadlock detection should be race free while we minimize excessive file_lock_lock thrashing. Finally, in order to avoid a lock inversion problem when handling /proc/locks output we must ensure that manipulations of the fl_block list are also protected by the file_lock_lock. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: encapsulate the fl_link list handlingJeff Layton1-9/+36
Move the fl_link list handling routines into a separate set of helpers. Also ensure that locks and requests are always put on global lists last (after fully initializing them) and are taken off before unintializing them. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: make "added" in __posix_lock_file a boolJeff Layton1-4/+5
Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: comment cleanups and clarificationsJeff Layton1-8/+13
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: make generic_add_lease and generic_delete_lease staticJeff Layton1-2/+2
Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29cifs: use posix_unblock_lock instead of locks_delete_blockJeff Layton1-2/+1
commit 66189be74 (CIFS: Fix VFS lock usage for oplocked files) exported the locks_delete_block symbol. There's already an exported helper function that provides this capability however, so make cifs use that instead and turn locks_delete_block back into a static function. Note that if fl->fl_next == NULL then this lock has already been through locks_delete_block(), so we should be OK to ignore an ENOENT error here and simply not retry the lock. Cc: Pavel Shilovsky <piastryyy@gmail.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-06-29locks: drop the unused filp argument to posix_unblock_lockJeff Layton1-3/+1
Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-02-22new helper: file_inode(file)Al Viro1-12/+12
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-10-09nfs: disintegrate UAPI for nfsJ. Bruce Fields1-11/+9
This is to complete part of the Userspace API (UAPI) disintegration for which the preparatory patches were pulled recently. After these patches, userspace headers will be segregated into: include/uapi/linux/.../foo.h for the userspace interface stuff, and: include/linux/.../foo.h for the strictly kernel internal stuff. Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2012-09-26switch simple cases of fget_light to fdgetAl Viro1-11/+9
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-20vfs: don't treat fl_type as a bitmapJeff Layton1-3/+3
The rules for fl_type are rather convoluted. Typically it's treated as holding specific values, except in the case of LOCK_MAND, in which case it can be or'ed with LOCK_READ|LOCK_WRITE. On some arches F_WRLCK == 2 and F_UNLCK == 3, so and'ing with F_WRLCK will also catch the F_UNLCK case. It's unlikely in either case here that we'd ever see F_UNLCK since those shouldn't end up on any lists, but it's still best to be consistent. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2012-08-01locks: remove unused lm_release_privateJ. Bruce Fields1-5/+1
In commit 3b6e2723f32d ("locks: prevent side-effects of locks_release_private before file_lock is initialized") we removed the last user of lm_release_private without removing the field itself. Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-31Merge branch 'nfsd-next' of git://linux-nfs.org/~bfields/linuxLinus Torvalds1-17/+11
Pull nfsd changes from J. Bruce Fields: "This has been an unusually quiet cycle--mostly bugfixes and cleanup. The one large piece is Stanislav's work to containerize the server's grace period--but that in itself is just one more step in a not-yet-complete project to allow fully containerized nfs service. There are a number of outstanding delegation, container, v4 state, and gss patches that aren't quite ready yet; 3.7 may be wilder." * 'nfsd-next' of git://linux-nfs.org/~bfields/linux: (35 commits) NFSd: make boot_time variable per network namespace NFSd: make grace end flag per network namespace Lockd: move grace period management from lockd() to per-net functions LockD: pass actual network namespace to grace period management functions LockD: manage grace list per network namespace SUNRPC: service request network namespace helper introduced NFSd: make nfsd4_manager allocated per network namespace context. LockD: make lockd manager allocated per network namespace LockD: manage grace period per network namespace Lockd: add more debug to host shutdown functions Lockd: host complaining function introduced LockD: manage used host count per networks namespace LockD: manage garbage collection timeout per networks namespace LockD: make garbage collector network namespace aware. LockD: mark host per network namespace on garbage collect nfsd4: fix missing fault_inject.h include locks: move lease-specific code out of locks_delete_lock locks: prevent side-effects of locks_release_private before file_lock is initialized NFSd: set nfsd_serv to NULL after service destruction NFSd: introduce nfsd_destroy() helper ...
2012-07-27locks: move lease-specific code out of locks_delete_lockJ. Bruce Fields1-6/+5
No point putting something only used by one caller into common code. Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2012-07-27locks: prevent side-effects of locks_release_private before file_lock is ↵Filipe Brandenburger1-11/+6
initialized When calling fcntl(fd, F_SETLEASE, lck) [with lck=F_WRLCK or F_RDLCK], the custom signal or owner (if any were previously set using F_SETSIG or F_SETOWN fcntls) would be reset when F_SETLEASE was called for the second time on the same file descriptor. This bug is a regression of 2.6.37 and is described here: https://bugzilla.kernel.org/show_bug.cgi?id=43336 This patch reverts a commit from Oct 2004 (with subject "nfs4 lease: move the f_delown processing") which originally introduced the lm_release_private callback. Signed-off-by: Filipe Brandenburger <filbranden@gmail.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2012-07-23locks: fix checking of fcntl_setlease argumentJ. Bruce Fields1-3/+3
The only checks of the long argument passed to fcntl(fd,F_SETLEASE,.) are done after converting the long to an int. Thus some illegal values may be let through and cause problems in later code. [ They actually *don't* cause problems in mainline, as of Dave Jones's commit 8d657eb3b438 "Remove easily user-triggerable BUG from generic_setlease", but we should fix this anyway. And this patch will be necessary to fix real bugs on earlier kernels. ] Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-13Remove easily user-triggerable BUG from generic_setleaseDave Jones1-1/+1
This can be trivially triggered from userspace by passing in something unexpected. kernel BUG at fs/locks.c:1468! invalid opcode: 0000 [#1] SMP RIP: 0010:generic_setlease+0xc2/0x100 Call Trace: __vfs_setlease+0x35/0x40 fcntl_setlease+0x76/0x150 sys_fcntl+0x1c6/0x810 system_call_fastpath+0x1a/0x1f Signed-off-by: Dave Jones <davej@redhat.com> Cc: stable@kernel.org # 3.2+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29switch flock to fget_light/fput_lightAl Viro1-2/+3
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-05-23Merge branch 'for-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull user namespace enhancements from Eric Biederman: "This is a course correction for the user namespace, so that we can reach an inexpensive, maintainable, and reasonably complete implementation. Highlights: - Config guards make it impossible to enable the user namespace and code that has not been converted to be user namespace safe. - Use of the new kuid_t type ensures the if you somehow get past the config guards the kernel will encounter type errors if you enable user namespaces and attempt to compile in code whose permission checks have not been updated to be user namespace safe. - All uids from child user namespaces are mapped into the initial user namespace before they are processed. Removing the need to add an additional check to see if the user namespace of the compared uids remains the same. - With the user namespaces compiled out the performance is as good or better than it is today. - For most operations absolutely nothing changes performance or operationally with the user namespace enabled. - The worst case performance I could come up with was timing 1 billion cache cold stat operations with the user namespace code enabled. This went from 156s to 164s on my laptop (or 156ns to 164ns per stat operation). - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most uid/gid setting system calls treat these value specially anyway so attempting to use -1 as a uid would likely cause entertaining failures in userspace. - If setuid is called with a uid that can not be mapped setuid fails. I have looked at sendmail, login, ssh and every other program I could think of that would call setuid and they all check for and handle the case where setuid fails. - If stat or a similar system call is called from a context in which we can not map a uid we lie and return overflowuid. The LFS experience suggests not lying and returning an error code might be better, but the historical precedent with uids is different and I can not think of anything that would break by lying about a uid we can't map. - Capabilities are localized to the current user namespace making it safe to give the initial user in a user namespace all capabilities. My git tree covers all of the modifications needed to convert the core kernel and enough changes to make a system bootable to runlevel 1." Fix up trivial conflicts due to nearby independent changes in fs/stat.c * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits) userns: Silence silly gcc warning. cred: use correct cred accessor with regards to rcu read lock userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq userns: Convert cgroup permission checks to use uid_eq userns: Convert tmpfs to use kuid and kgid where appropriate userns: Convert sysfs to use kgid/kuid where appropriate userns: Convert sysctl permission checks to use kuid and kgids. userns: Convert proc to use kuid/kgid where appropriate userns: Convert ext4 to user kuid/kgid where appropriate userns: Convert ext3 to use kuid/kgid where appropriate userns: Convert ext2 to use kuid/kgid where appropriate. userns: Convert devpts to use kuid/kgid where appropriate userns: Convert binary formats to use kuid/kgid where appropriate userns: Add negative depends on entries to avoid building code that is userns unsafe userns: signal remove unnecessary map_cred_ns userns: Teach inode_capable to understand inodes whose uids map to other namespaces. userns: Fail exec for suid and sgid binaries with ids outside our user namespace. userns: Convert stat to return values mapped from kuids and kgids userns: Convert user specfied uids and gids in chown into kuids and kgid userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs ...
2012-05-03userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfsEric W. Biederman1-1/+1
Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-04-01CIFS: Fix VFS lock usage for oplocked filesPavel Shilovsky1-1/+2
We can deadlock if we have a write oplock and two processes use the same file handle. In this case the first process can't unlock its lock if the second process blocked on the lock in the same time. Fix it by using posix_lock_file rather than posix_lock_file_wait under cinode->lock_mutex. If we request a blocking lock and posix_lock_file indicates that there is another lock that prevents us, wait untill that lock is released and restart our call. Cc: stable@kernel.org Acked-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru> Signed-off-by: Steve French <sfrench@us.ibm.com>
2011-12-26vfs: fix handling of lock allocation failure in lease-break caseLinus Torvalds1-8/+3
Bruce Fields notes that commit 778fc546f749 ("locks: fix tracking of inprogress lease breaks") introduced a possible error pointer dereference on failure to allocate memory. locks_conflict() will dereference the passed-in new lease lock structure that may be an error pointer. This means an open (without O_NONBLOCK set) on a file with a lease applied (generally only done when Samba or nfsd (with v4) is running) could crash if a kmalloc() fails. So instead of playing games with IS_ERROR() all over the place, just check the allocation failure early. That makes the code more straightforward, and avoids this possible bad pointer dereference. Based-on-patch-by: J. Bruce Fields <bfields@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-25Merge branch 'for-3.2' of git://linux-nfs.org/~bfields/linuxLinus Torvalds1-83/+140
* 'for-3.2' of git://linux-nfs.org/~bfields/linux: (103 commits) nfs41: implement DESTROY_CLIENTID operation nfsd4: typo logical vs bitwise negate for want_mask nfsd4: allow NFS4_SHARE_SIGNAL_DELEG_WHEN_RESRC_AVAIL | NFS4_SHARE_PUSH_DELEG_WHEN_UNCONTENDED nfsd4: seq->status_flags may be used unitialized nfsd41: use SEQ4_STATUS_BACKCHANNEL_FAULT when cb_sequence is invalid nfsd4: implement new 4.1 open reclaim types nfsd4: remove unneeded CLAIM_DELEGATE_CUR workaround nfsd4: warn on open failure after create nfsd4: preallocate open stateid in process_open1() nfsd4: do idr preallocation with stateid allocation nfsd4: preallocate nfs4_file in process_open1() nfsd4: clean up open owners on OPEN failure nfsd4: simplify process_open1 logic nfsd4: make is_open_owner boolean nfsd4: centralize renew_client() calls nfsd4: typo logical vs bitwise negate nfs: fix bug about IPv6 address scope checking nfsd4: more robust ignoring of WANT bits in OPEN nfsd4: move name-length checks to xdr nfsd4: move access/deny validity checks to xdr code ...
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