diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index c0ad233..bee63d4 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -29,7 +29,6 @@ algorithms work. fiemap files locks - mandatory-locking mount_api quota seq_file diff --git a/Documentation/filesystems/locks.rst b/Documentation/filesystems/locks.rst index c5ae858..2642931 100644 --- a/Documentation/filesystems/locks.rst +++ b/Documentation/filesystems/locks.rst @@ -57,16 +57,9 @@ fcntl(), with all the problems that implies. 1.3 Mandatory Locking As A Mount Option --------------------------------------- -Mandatory locking, as described in -'Documentation/filesystems/mandatory-locking.rst' was prior to this release a -general configuration option that was valid for all mounted filesystems. This -had a number of inherent dangers, not the least of which was the ability to -freeze an NFS server by asking it to read a file for which a mandatory lock -existed. - -From this release of the kernel, mandatory locking can be turned on and off -on a per-filesystem basis, using the mount options 'mand' and 'nomand'. -The default is to disallow mandatory locking. The intention is that -mandatory locking only be enabled on a local filesystem as the specific need -arises. +Mandatory locking was prior to this release a general configuration option +that was valid for all mounted filesystems. This had a number of inherent +dangers, not the least of which was the ability to freeze an NFS server by +asking it to read a file for which a mandatory lock existed. +Such option was dropped in Kernel v5.14. diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c index bdeb271..d8c3106 100644 --- a/fs/ceph/locks.c +++ b/fs/ceph/locks.c @@ -302,9 +302,6 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl) if (!(fl->fl_flags & FL_FLOCK)) return -ENOLCK; - /* No mandatory locks */ - if (fl->fl_type & LOCK_MAND) - return -EOPNOTSUPP; dout("ceph_flock, fl_file: %p\n", fl->fl_file); diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c index c559827..078ef29 100644 --- a/fs/gfs2/file.c +++ b/fs/gfs2/file.c @@ -1338,8 +1338,6 @@ static int gfs2_flock(struct file *file, int cmd, struct file_lock *fl) { if (!(fl->fl_flags & FL_FLOCK)) return -ENOLCK; - if (fl->fl_type & LOCK_MAND) - return -EOPNOTSUPP; if (fl->fl_type == F_UNLCK) { do_unflock(file, fl); diff --git a/fs/locks.c b/fs/locks.c index 3d6fb4a..0fca9d6 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -2,117 +2,11 @@ /* * linux/fs/locks.c * - * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. - * Doug Evans (dje@spiff.uucp), August 07, 1992 + * We implement four types of file locks: BSD locks, posix locks, open + * file description locks, and leases. For details about BSD locks, + * see the flock(2) man page; for details about the other three, see + * fcntl(2). * - * Deadlock detection added. - * FIXME: one thing isn't handled yet: - * - mandatory locks (requires lots of changes elsewhere) - * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. - * - * Miscellaneous edits, and a total rewrite of posix_lock_file() code. - * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 - * - * Converted file_lock_table to a linked list from an array, which eliminates - * the limits on how many active file locks are open. - * Chad Page (pageone@netcom.com), November 27, 1994 - * - * Removed dependency on file descriptors. dup()'ed file descriptors now - * get the same locks as the original file descriptors, and a close() on - * any file descriptor removes ALL the locks on the file for the current - * process. Since locks still depend on the process id, locks are inherited - * after an exec() but not after a fork(). This agrees with POSIX, and both - * BSD and SVR4 practice. - * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 - * - * Scrapped free list which is redundant now that we allocate locks - * dynamically with kmalloc()/kfree(). - * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 - * - * Implemented two lock personalities - FL_FLOCK and FL_POSIX. - * - * FL_POSIX locks are created with calls to fcntl() and lockf() through the - * fcntl() system call. They have the semantics described above. - * - * FL_FLOCK locks are created with calls to flock(), through the flock() - * system call, which is new. Old C libraries implement flock() via fcntl() - * and will continue to use the old, broken implementation. - * - * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated - * with a file pointer (filp). As a result they can be shared by a parent - * process and its children after a fork(). They are removed when the last - * file descriptor referring to the file pointer is closed (unless explicitly - * unlocked). - * - * FL_FLOCK locks never deadlock, an existing lock is always removed before - * upgrading from shared to exclusive (or vice versa). When this happens - * any processes blocked by the current lock are woken up and allowed to - * run before the new lock is applied. - * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 - * - * Removed some race conditions in flock_lock_file(), marked other possible - * races. Just grep for FIXME to see them. - * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. - * - * Addressed Dmitry's concerns. Deadlock checking no longer recursive. - * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep - * once we've checked for blocking and deadlocking. - * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. - * - * Initial implementation of mandatory locks. SunOS turned out to be - * a rotten model, so I implemented the "obvious" semantics. - * See 'Documentation/filesystems/mandatory-locking.rst' for details. - * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. - * - * Don't allow mandatory locks on mmap()'ed files. Added simple functions to - * check if a file has mandatory locks, used by mmap(), open() and creat() to - * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference - * Manual, Section 2. - * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. - * - * Tidied up block list handling. Added '/proc/locks' interface. - * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. - * - * Fixed deadlock condition for pathological code that mixes calls to - * flock() and fcntl(). - * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. - * - * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use - * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to - * guarantee sensible behaviour in the case where file system modules might - * be compiled with different options than the kernel itself. - * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. - * - * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel - * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. - * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. - * - * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK - * locks. Changed process synchronisation to avoid dereferencing locks that - * have already been freed. - * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. - * - * Made the block list a circular list to minimise searching in the list. - * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. - * - * Made mandatory locking a mount option. Default is not to allow mandatory - * locking. - * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. - * - * Some adaptations for NFS support. - * Olaf Kirch (okir@monad.swb.de), Dec 1996, - * - * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. - * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. - * - * Use slab allocator instead of kmalloc/kfree. - * Use generic list implementation from . - * Sped up posix_locks_deadlock by only considering blocked locks. - * Matthew Wilcox , March, 2000. - * - * Leases and LOCK_MAND - * Matthew Wilcox , June, 2000. - * Stephen Rothwell , June, 2000. * * Locking conflicts and dependencies: * If multiple threads attempt to lock the same byte (or flock the same file) @@ -461,8 +355,6 @@ static void locks_move_blocks(struct file_lock *new, struct file_lock *fl) } static inline int flock_translate_cmd(int cmd) { - if (cmd & LOCK_MAND) - return cmd & (LOCK_MAND | LOCK_RW); switch (cmd) { case LOCK_SH: return F_RDLCK; @@ -942,8 +834,6 @@ static bool flock_locks_conflict(struct file_lock *caller_fl, */ if (caller_fl->fl_file == sys_fl->fl_file) return false; - if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) - return false; return locks_conflict(caller_fl, sys_fl); } @@ -2116,11 +2006,9 @@ EXPORT_SYMBOL(locks_lock_inode_wait); * - %LOCK_SH -- a shared lock. * - %LOCK_EX -- an exclusive lock. * - %LOCK_UN -- remove an existing lock. - * - %LOCK_MAND -- a 'mandatory' flock. - * This exists to emulate Windows Share Modes. + * - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED) * - * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other - * processes read and write access respectively. + * %LOCK_MAND support has been removed from the kernel. */ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) { @@ -2137,9 +2025,22 @@ SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) cmd &= ~LOCK_NB; unlock = (cmd == LOCK_UN); - if (!unlock && !(cmd & LOCK_MAND) && - !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) + if (!unlock && !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) + goto out_putf; + + /* + * LOCK_MAND locks were broken for a long time in that they never + * conflicted with one another and didn't prevent any sort of open, + * read or write activity. + * + * Just ignore these requests now, to preserve legacy behavior, but + * throw a warning to let people know that they don't actually work. + */ + if (cmd & LOCK_MAND) { + pr_warn_once("Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n"); + error = 0; goto out_putf; + } lock = flock_make_lock(f.file, cmd, NULL); if (IS_ERR(lock)) { @@ -2718,6 +2619,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, struct inode *inode = NULL; unsigned int fl_pid; struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); + int type; fl_pid = locks_translate_pid(fl, proc_pidns); /* @@ -2745,11 +2647,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, seq_printf(f, " %s ", (inode == NULL) ? "*NOINODE*" : "ADVISORY "); } else if (IS_FLOCK(fl)) { - if (fl->fl_type & LOCK_MAND) { - seq_puts(f, "FLOCK MSNFS "); - } else { - seq_puts(f, "FLOCK ADVISORY "); - } + seq_puts(f, "FLOCK ADVISORY "); } else if (IS_LEASE(fl)) { if (fl->fl_flags & FL_DELEG) seq_puts(f, "DELEG "); @@ -2765,17 +2663,10 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl, } else { seq_puts(f, "UNKNOWN UNKNOWN "); } - if (fl->fl_type & LOCK_MAND) { - seq_printf(f, "%s ", - (fl->fl_type & LOCK_READ) - ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " - : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); - } else { - int type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type; + type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type; - seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" : - (type == F_RDLCK) ? "READ" : "UNLCK"); - } + seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" : + (type == F_RDLCK) ? "READ" : "UNLCK"); if (inode) { /* userspace relies on this representation of dev_t */ seq_printf(f, "%d %02x:%02x:%lu ", fl_pid, diff --git a/fs/namei.c b/fs/namei.c index 1946d96..1f9d218 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3076,9 +3076,7 @@ static int handle_truncate(struct user_namespace *mnt_userns, struct file *filp) int error = get_write_access(inode); if (error) return error; - /* - * Refuse to truncate files with mandatory locks held on them. - */ + error = security_path_truncate(path); if (!error) { error = do_truncate(mnt_userns, path->dentry, 0, diff --git a/fs/nfs/file.c b/fs/nfs/file.c index aa353fd..24e7dcc 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -843,15 +843,6 @@ int nfs_flock(struct file *filp, int cmd, struct file_lock *fl) if (!(fl->fl_flags & FL_FLOCK)) return -ENOLCK; - /* - * The NFSv4 protocol doesn't support LOCK_MAND, which is not part of - * any standard. In principle we might be able to support LOCK_MAND - * on NFSv2/3 since NLMv3/4 support DOS share modes, but for now the - * NFS code is not set up for it. - */ - if (fl->fl_type & LOCK_MAND) - return -EINVAL; - if (NFS_SERVER(inode)->flags & NFS_MOUNT_LOCAL_FLOCK) is_local = 1; diff --git a/fs/read_write.c b/fs/read_write.c index af057c5..0074afa 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -368,10 +368,6 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t if (unlikely((ssize_t) count < 0)) return -EINVAL; - /* - * ranged mandatory locking does not apply to streams - it makes sense - * only for files where position has a meaning. - */ if (ppos) { loff_t pos = *ppos; diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/fcntl.h index 9dc0bf0..ecd0f5b 100644 --- a/include/uapi/asm-generic/fcntl.h +++ b/include/uapi/asm-generic/fcntl.h @@ -181,6 +181,10 @@ struct f_owner_ex { blocking */ #define LOCK_UN 8 /* remove lock */ +/* + * LOCK_MAND support has been removed from the kernel. We leave the symbols + * here to not break legacy builds, but these should not be used in new code. + */ #define LOCK_MAND 32 /* This is a mandatory flock ... */ #define LOCK_READ 64 /* which allows concurrent read operations */ #define LOCK_WRITE 128 /* which allows concurrent write operations */