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* userns: Allow the userns root to mount of devptsEric W. Biederman2013-01-27
| | | | | | | | | | | | | | | | - The context in which devpts is mounted has no effect on the creation of ptys as the /dev/ptmx interface has been used by unprivileged users for many years. - Only support unprivileged mounts in combination with the newinstance option to ensure that mounting of /dev/pts in a user namespace will not allow the options of an existing mount of devpts to be modified. - Create /dev/pts/ptmx as the root user in the user namespace that mounts devpts so that it's permissions to be changed. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* TTY: devpts, document devpts inode operationsJiri Slaby2012-10-22
| | | | | | | | Add kernel-doc texts for some devpts functions, i.e. document them. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* TTY: devpts, do not set driver_dataJiri Slaby2012-10-22
| | | | | | | | | | | | | | | | The goal is to stop setting and using tty->driver_data in devpts code. It should be used solely by the driver's code, pty in this case. Now driver_data are managed only in the pty driver. devpts_pty_new is switched to accept what we used to dig out of tty_struct, i.e. device node number and index. This also removes a note about driver_data being set outside of the driver. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* TTY: devpts, return created inode from devpts_pty_newJiri Slaby2012-10-22
| | | | | | | | | | | | | | | | | The goal is to stop setting and using tty->driver_data in devpts code. It should be used solely by the driver's code, pty in this case. For the cleanup of layering, we will need the inode created in devpts_pty_new to be stored into slave's driver_data. So we convert devpts_pty_new to return the inode or an ERR_PTR-encoded error in case of failure. The move of 'inode = new_inode(sb);' from declarators to the code is only cosmetical, but it makes the code easier to read. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* TTY: devpts, don't care about TTY in devpts_get_ttyJiri Slaby2012-10-22
| | | | | | | | | | | | | | | | The goal is to stop setting and using tty->driver_data in devpts code. It should be used solely by the driver's code, pty in this case. First, here we remove TTY from devpts_get_tty and rename it to devpts_get_priv. Note we do not remove type safety, we just shift the [implicit] (void *) cast one layer up. index was unused in devpts_get_tty, so remove that from the prototype too. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* VFS: Pass mount flags to sget()David Howells2012-07-14
| | | | | | | | | Pass mount flags to sget() so that it can use them in initialising a new superblock before the set function is called. They could also be passed to the compare function. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* userns: Convert devpts to use kuid/kgid where appropriateEric W. Biederman2012-05-15
| | | | | Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2012-03-21
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile 1 from Al Viro: "This is _not_ all; in particular, Miklos' and Jan's stuff is not there yet." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits) ext4: initialization of ext4_li_mtx needs to be done earlier debugfs-related mode_t whack-a-mole hfsplus: add an ioctl to bless files hfsplus: change finder_info to u32 hfsplus: initialise userflags qnx4: new helper - try_extent() qnx4: get rid of qnx4_bread/qnx4_getblk take removal of PF_FORKNOEXEC to flush_old_exec() trim includes in inode.c um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it um: embed ->stub_pages[] into mmu_context gadgetfs: list_for_each_safe() misuse ocfs2: fix leaks on failure exits in module_init ecryptfs: make register_filesystem() the last potential failure exit ntfs: forgets to unregister sysctls on register_filesystem() failure logfs: missing cleanup on register_filesystem() failure jfs: mising cleanup on register_filesystem() failure make configfs_pin_fs() return root dentry on success configfs: configfs_create_dir() has parent dentry in dentry->d_parent configfs: sanitize configfs_create() ...
| * switch open-coded instances of d_make_root() to new helperAl Viro2012-03-20
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | tty: rework pty count limitingKonstantin Khlebnikov2012-01-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After adding devpts multiple-insrances sysctl kernel.pty.max limit pty count for each devpts instance independently, while kernel.pty.nr shows total pty count. This patch restores sysctl kernel.pty.max as global limit (4096 by default), adds pty reseve for main devpts (mounted without "newinstance" argument), and new sysctl to tune it: kernel.pty.reserve (1024 by default) Also it adds devpts mount option "max=%d" to limit pty count for each devpts instance independently. (by default NR_UNIX98_PTY_MAX == 2^20) Thus devpts instances in containers cannot eat up all available pty even if we didn't set any limits, while with "max" argument we can adjust limits more precisely. Plus, now open("/dev/ptmx") return -ENOSPC in case lack of pty indexes, this is more informative than -EIO. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* | tty: move pty count limiting into devptsKonstantin Khlebnikov2012-01-24
|/ | | | | | | | Let's move this stuff to the better place, where we can account pty right in tty-indexes managing code. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* devpts: fix double-free on mount failureAl Viro2012-01-08
| | | | | | | | | devpts_kill_sb() is called even if devpts_fill_super() fails; we should not do that kfree() in the latter, especially not with ->s_fs_info left pointing to freed object. Double kfree() is a Bad Thing(tm)... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: switch ->show_options() to struct dentry *Al Viro2012-01-06
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* filesystems: add set_nlink()Miklos Szeredi2011-11-02
| | | | | | | | | Replace remaining direct i_nlink updates with a new set_nlink() updater function. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
* filesystems: add missing nlink wrappersMiklos Szeredi2011-11-02
| | | | | | | Replace direct i_nlink updates with the respective updater function (inc_nlink, drop_nlink, clear_nlink, inode_dec_link_count). Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
* fs/devpts/inode.c: correctly check d_alloc_name() return code in ↵Andrey Vagin2011-03-22
| | | | | | | | | | | | | devpts_pty_new() d_alloc_name return NULL in case error, but we expect errno in devpts_pty_new. Addresses http://bugzilla.openvz.org/show_bug.cgi?id=1758 Signed-off-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: devpts_pty_new() return -ENOMEM if dentry allocation failedAndrey Vagin2011-03-21
| | | | | | | | | | | In this case nobody can open a slave point, so will be better return from devpts_pty_new() Now we should not check error code from d_find_alias() in devpts_pty_kill(), because the dentry exists all times. Signed-off-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* convert get_sb_single() usersAl Viro2010-10-29
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Simplify devpts_get_sb() failure exitsAl Viro2010-05-21
| | | | | | postpone simple_set_mnt() until we know we won't fail. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* include cleanup: Update gfp.h and slab.h includes to prepare for breaking ↵Tejun Heo2010-03-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
* devpts_get_tty() should validate inodeSukadev Bhattiprolu2009-12-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | devpts_get_tty() assumes that the inode passed in is associated with a valid pty. But if the only reference to the pty is via a bind-mount, the inode passed to devpts_get_tty() while valid, would refer to a pty that no longer exists. With a lot of debug effort, Grzegorz Nosek developed a small program (see below) to reproduce a crash on recent kernels. This crash is a regression introduced by the commit: commit 527b3e4773628b30d03323a2cb5fb0d84441990f Author: Sukadev Bhattiprolu <sukadev@us.ibm.com> Date: Mon Oct 13 10:43:08 2008 +0100 To fix, ensure that the dentry associated with the inode has not yet been deleted/unhashed by devpts_pty_kill(). See also: https://lists.linux-foundation.org/pipermail/containers/2009-July/019273.html tty-bug.c: #define _GNU_SOURCE #include <fcntl.h> #include <sched.h> #include <stdlib.h> #include <sys/mount.h> #include <sys/signal.h> #include <unistd.h> #include <stdio.h> #include <linux/fs.h> void dummy(int sig) { } static int child(void *unused) { int fd; signal(SIGINT, dummy); signal(SIGHUP, dummy); pause(); /* cheesy synchronisation to wait for /dev/pts/0 to appear */ mount("/dev/pts/0", "/dev/console", NULL, MS_BIND, NULL); sleep(2); fd = open("/dev/console", O_RDWR); dup(0); dup(0); write(1, "Hello world!\n", sizeof("Hello world!\n")-1); return 0; } int main(void) { pid_t pid; char *stack; stack = malloc(16384); pid = clone(child, stack+16384, CLONE_NEWNS|SIGCHLD, NULL); open("/dev/ptmx", O_RDWR|O_NOCTTY|O_NONBLOCK); unlockpt(fd); grantpt(fd); sleep(2); kill(pid, SIGHUP); sleep(1); return 0; /* exit before child opens /dev/console */ } Reported-by: Grzegorz Nosek <root@localdomain.pl> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Tested-by: Serge Hallyn <serue@us.ibm.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* Move magic numbers into magic.hNick Black2009-09-23
| | | | | | | | | | | | Move various magic-number definitions into magic.h. Signed-off-by: Nick Black <dank@qemfd.net> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "David S. Miller" <davem@davemloft.net> Cc: Casey Schaufler <casey@schaufler-ca.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devpts: remove module-related codeH. Peter Anvin2009-06-24
| | | | | | | | | | | | These days, the devpts filesystem is closely integrated with the pty memory management, and cannot be built as a module, even less removed from the kernel. Accordingly, remove all module-related stuff from this filesystem. [ v2: only remove code that's actually dead ] Signed-off-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* devpts: unregister the file system on errorAlan Cox2009-06-11
| | | | | | | Closes-bug: http://bugzilla.kernel.org/show_bug.cgi?id=13429 Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devpts: correctly set default optionsSukadev Bhattiprolu2009-05-15
| | | | | | | | | | | | | | | | | | | | | | | | | | devpts_get_sb() calls memset(0) to clear mount options and calls parse_mount_options() if user specified any mount options. The memset(0) is bogus since the 'mode' and 'ptmxmode' options are non-zero by default. parse_mount_options() restores options to default anyway and can properly deal with NULL mount options. So in devpts_get_sb() remove memset(0) and call parse_mount_options() even for NULL mount options. Bug reported by Eric Paris: http://lkml.org/lkml/2009/5/7/448. Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Tested-by: Marc Dionne <marc.c.dionne@gmail.com> Reported-by: Eric Paris <eparis@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Reviewed-by: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Convert obvious places to deactivate_locked_super()Al Viro2009-05-09
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge code for single and multiple-instance mountsSukadev Bhattiprolu2009-03-27
| | | | | | | | | | | | | | | | | | | new_pts_mount() (including the get_sb_nodev()), shares a lot of code with init_pts_mount(). The only difference between them is the 'test-super' function passed into sget(). Move all common code into devpts_get_sb() and remove the new_pts_mount() and init_pts_mount() functions, Changelog[v3]: [Serge Hallyn]: Remove unnecessary printk()s Changelog[v2]: (Christoph Hellwig): Merge code in 'do_pts_mount()' into devpts_get_sb() Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Tested-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Remove get_init_pts_sb()Sukadev Bhattiprolu2009-03-27
| | | | | | | | | | With mknod_ptmx() moved to devpts_get_sb(), init_pts_mount() becomes a wrapper around get_init_pts_sb(). Remove get_init_pts_sb() and fold code into init_pts_mount(). Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Move common mknod_ptmx() calls into callerSukadev Bhattiprolu2009-03-27
| | | | | | | | | | We create 'ptmx' node in both single-instance and multiple-instance mounts. So devpts_get_sb() can call mknod_ptmx() once rather than have both modes calling mknod_ptmx() separately. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Parse mount options just once and copy them to super blockSukadev Bhattiprolu2009-03-27
| | | | | | | | | Since all the mount option parsing is done in devpts, we could do it just once and pass it around in devpts functions and eventually store it in the super block. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Unroll essentials of do_remount_sb() into devptsSukadev Bhattiprolu2009-03-27
| | | | | | | | | | | | | | | | | On remount, devpts fs only needs to parse the mount options. Users cannot directly create/dirty files in /dev/pts so the MS_RDONLY flag and shrinking the dcache does not really apply to devpts. So effectively on remount, devpts only parses the mount options and updates these options in its super block. As such, we could replace do_remount_sb() call with a direct parse_mount_options(). Doing so enables subsequent patches to avoid parsing the mount options twice and simplify the code. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: simple_set_mnt() should return voidSukadev Bhattiprolu2009-03-27
| | | | | | | | | | | | | | | | | | | | | | | simple_set_mnt() is defined as returning 'int' but always returns 0. Callers assume simple_set_mnt() never fails and don't properly cleanup if it were to _ever_ fail. For instance, get_sb_single() and get_sb_nodev() should: up_write(sb->s_unmount); deactivate_super(sb); if simple_set_mnt() fails. Since simple_set_mnt() never fails, would be cleaner if it did not return anything. [akpm@linux-foundation.org: fix build] Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* devpts: Must release s_umount on errorSukadev Bhattiprolu2009-03-27
| | | | | | | | | We should drop the ->s_umount mutex if an error occurs after the sget()/grab_super() call. This was introduced when adding support for multiple instances of devpts and noticed during a code review/reorg. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* devpts: remove graffitiAlexey Dobriyan2009-03-10
| | | | | | | | | | Very annoying when working with containters. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* zero i_uid/i_gid on inode allocationAl Viro2009-01-05
| | | | | | | | | ... and don't bother in callers. Don't bother with zeroing i_blocks, while we are at it - it's already been zeroed. i_mode is not worth the effort; it has no common default value. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* CRED: Wrap task credential accesses in the devpts filesystemDavid Howells2009-01-02
| | | | | | | | | | | | | | | Wrap access to task credentials so that they can be separated more easily from the task_struct during the introduction of COW creds. Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id(). Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more sense to use RCU directly rather than a convenient wrapper; these will be addressed by later patches. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devpts: fix unused function warningAndrew Morton2009-01-02
| | | | | | | | fs/devpts/inode.c:324: warning: 'compare_init_pts_sb' defined but not used Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* devpts: Coding style clean upAlan Cox2009-01-02
| | | | | | | Just nail the oddments now while this code is being touched Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Enable multiple instances of devptsSukadev Bhattiprolu2009-01-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To support containers, allow multiple instances of devpts filesystem, such that indices of ptys allocated in one instance are independent of ptys allocated in other instances of devpts. But to preserve backward compatibility, enable this support for multiple instances only if: - CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and - '-o newinstance' mount option is specified while mounting devpts To use multi-instance mount, a container startup script could: $ ns_exec -cm /bin/bash $ umount /dev/pts $ mount -t devpts -o newinstance lxcpts /dev/pts $ mount -o bind /dev/pts/ptmx /dev/ptmx $ /usr/sbin/sshd -p 1234 where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs /bin/bash in the child process. A pty created by the sshd is not visible in the original mount of /dev/pts. USER-SPACE-IMPACT: - See Documentation/fs/devpts.txt (included in next patch) for user- space impact in multi-instance and mixed-mode operation. TODO: - Update mount(8), pts(4) man pages. Highlight impact of not redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount. Changelog[v6]: - [Dave Hansen] Use new get_init_pts_sb() interface - [Serge Hallyn] Don't bother displaying 'newinstance' in show_options - [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1. - [Serge Hallyn] Check error return from get_sb_single() (now get_init_pts_sb()) - devpts_pty_kill(): don't dput error dentries Changelog[v5]: - Move get_sb_ref() definition to earlier patch - Move usage info to Documentation/filesystems/devpts.txt (next patch) - Make ptmx node even in init_pts_ns, now that default mode is 0000 (defined in earlier patch, enabled here). - Cache ptmx dentry and use to update mode during remount (defined in earlier patch, enabled here). - Bugfix: explicitly ignore newinstance on remount (if newinstance was specified on remount of initial mount, it would be ignored but /proc/mounts would imply that the option was set) Changelog[v4]: - Update patch description to address H. Peter Anvin's comments - Consolidate multi-instance mode code under new config token, CONFIG_DEVPTS_MULTIPLE_INSTANCE. - Move usage-details from patch description to Documentation/fs/devpts.txt Changelog[v3]: - Rename new mount option to 'newinstance' - Create ptmx nodes only in 'newinstance' mounts - Bugfix: parse_mount_options() modifies @data but since we need to parse the @data twice (once in devpts_get_sb() and once during do_remount_sb()), parse a local copy of @data in devpts_get_sb(). (restructured code in devpts_get_sb() to fix this) Changelog[v2]: - Support both single-mount and multiple-mount semantics and provide '-onewmnt' option to select the semantics. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Define get_init_pts_sb()Sukadev Bhattiprolu2009-01-02
| | | | | | | | | | | | | See comments in the function header for details. The new interface will be used in a follow-on patch. Changelog [v2]: [Dave Hansen] Replace get_sb_ref() in fs/super.c with get_init_pts_sb() and make the new interface private to devpts Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Define mknod_ptmx()Sukadev Bhattiprolu2009-01-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | /dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx, allocates the next pty index and the associated device shows up in the devpts fs as /dev/pts/n. Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx we would be unable to determine which instance of the devpts is being accessed. So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx' node to identify the superblock and hence the devpts instance. This patch adds ability for the kernel to internally create the [ptmx, c, 5:2] device when mounting devpts filesystem. Since the ptmx node in devpts is new and may surprise some userspace scripts, the default permissions for the new node is 0000. These permissions can be changed either using chmod or by remounting with the new '-o ptmxmode=0666' mount option. Changelog[v5]: - [Serge Hallyn bugfix]: Letting new_inode() assign inode number to ptmx can collide with hand-assigning inode numbers to ptys. So, hand-assign specific inode number to ptmx node also. - [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating ptmx node - [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx() wih d_alloc_name() (lookup during ->get_sb() locks up system). To simplify patchset, fold the ptmx_dentry patch into this. Changelog[v4]: - Change default permissions of pts/ptmx node to 0000. - Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES. Changelog[v3]: - Rename ptmx_mode to ptmxmode (for consistency with 'newinstance') Changelog[v2]: - [H. Peter Anvin] Remove mknod() system call support and create the ptmx node internally. Changelog[v1]: - Earlier version of this patch enabled creating /dev/pts/tty as well. As pointed out by Al Viro and H. Peter Anvin, that is not really necessary. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Extract option parsing to new functionSukadev Bhattiprolu2009-01-02
| | | | | | | | | Move code to parse mount options into a separate function so it can (later) be shared between mount and remount operations. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Per-mount 'config' objectSukadev Bhattiprolu2009-01-02
| | | | | | | | | | With support for multiple mounts of devpts, the 'config' structure really represents per-mount options rather than config parameters. Rename 'config' structure to 'pts_mount_opts' and store it in the super-block. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Per-mount allocated_ptysSukadev Bhattiprolu2009-01-02
| | | | | | | | | | | | | To enable multiple mounts of devpts, 'allocated_ptys' must be a per-mount variable rather than a global variable. Move 'allocated_ptys' into the super_block's s_fs_info. Changelog[v2]: Define and use DEVPTS_SB() wrapper. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Remove devpts_root globalSukadev Bhattiprolu2009-01-02
| | | | | | | | | | | | | Remove the 'devpts_root' global variable and find the root dentry using the super_block. The super-block can be found from the device inode, using the new wrapper, pts_sb_from_inode(). Changelog: This patch is based on an earlier patchset from Serge Hallyn and Matt Helsley. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* CRED: Wrap task credential accesses in the devpts filesystemDavid Howells2008-11-13
| | | | | | | | | | | | | | | | Wrap access to task credentials so that they can be separated more easily from the task_struct during the introduction of COW creds. Change most current->(|e|s|fs)[ug]id to current_(|e|s|fs)[ug]id(). Change some task->e?[ug]id to task_e?[ug]id(). In some places it makes more sense to use RCU directly rather than a convenient wrapper; these will be addressed by later patches. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* vfs: Use const for kernel parser tableSteven Whitehouse2008-10-13
| | | | | | | | | | | | | | This is a much better version of a previous patch to make the parser tables constant. Rather than changing the typedef, we put the "const" in all the various places where its required, allowing the __initconst exception for nfsroot which was the cause of the previous trouble. This was posted for review some time ago and I believe its been in -mm since then. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Cc: Alexander Viro <aviro@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Simplify devpts_pty_killSukadev Bhattiprolu2008-10-13
| | | | | | | | | | | | | | When creating a new pty, save the pty's inode in the tty->driver_data. Use this inode in pty_kill() to identify the devpts instance. Since we now have the inode for the pty, we can skip get_node() lookup and remove the unused get_node(). TODO: - check if the mutex_lock is needed in pty_kill(). Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Simplify devpts_pty_new()Sukadev Bhattiprolu2008-10-13
| | | | | | | | | | devpts_pty_new() is called when setting up a new pty and would not will not have an existing dentry or inode for the pty. So don't bother looking for an existing dentry - just create a new one. Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Simplify devpts_get_tty()Sukadev Bhattiprolu2008-10-13
| | | | | | | | | As pointed out by H. Peter Anvin, since the inode for the pty is known, we don't need to look it up. Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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