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* RCU'd vfsmountsAl Viro2013-11-091-48/+87
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * RCU-delayed freeing of vfsmounts * vfsmount_lock replaced with a seqlock (mount_lock) * sequence number from mount_lock is stored in nameidata->m_seq and used when we exit RCU mode * new vfsmount flag - MNT_SYNC_UMOUNT. Set by umount_tree() when its caller knows that vfsmount will have no surviving references. * synchronize_rcu() done between unlocking namespace_sem in namespace_unlock() and doing pending mntput(). * new helper: legitimize_mnt(mnt, seq). Checks the mount_lock sequence number against seq, then grabs reference to mnt. Then it rechecks mount_lock again to close the race and either returns success or drops the reference it has acquired. The subtle point is that in case of MNT_SYNC_UMOUNT we can simply decrement the refcount and sod off - aforementioned synchronize_rcu() makes sure that final mntput() won't come until we leave RCU mode. We need that, since we don't want to end up with some lazy pathwalk racing with umount() and stealing the final mntput() from it - caller of umount() may expect it to return only once the fs is shut down and we don't want to break that. In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do full-blown mntput() in case of mount_lock sequence number mismatch happening just as we'd grabbed the reference, but in those cases we won't be stealing the final mntput() from anything that would care. * mntput_no_expire() doesn't lock anything on the fast path now. Incidentally, SMP and UP cases are handled the same way - no ifdefs there. * normal pathname resolution does *not* do any writes to mount_lock. It does, of course, bump the refcounts of vfsmount and dentry in the very end, but that's it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* split __lookup_mnt() in two functionsAl Viro2013-10-241-19/+23
| | | | | | | | Instead of passing the direction as argument (and checking it on every step through the hash chain), just have separate __lookup_mnt() and __lookup_mnt_last(). And use the standard iterators... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* new helpers: lock_mount_hash/unlock_mount_hashAl Viro2013-10-241-48/+48
| | | | | | | aka br_write_{lock,unlock} of vfsmount_lock. Inlines in fs/mount.h, vfsmount_lock extern moved over there as well. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* namespace.c: get rid of mnt_ghostsAl Viro2013-10-241-15/+7
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fold dup_mnt_ns() into its only surviving callerAl Viro2013-10-241-30/+18
| | | | | | should've been done 6 years ago... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* mnt_set_expiry() doesn't need vfsmount_lockAl Viro2013-10-241-2/+0
| | | | | | ->mnt_expire is protected by namespace_sem Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* finish_automount() doesn't need vfsmount_lock for removal from expiry listAl Viro2013-10-241-2/+0
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/namespace.c: bury long-dead defineAl Viro2013-10-241-2/+0
| | | | | | MNT_WRITER_UNDERFLOW_LIMIT has been missed 4 years ago when it became unused. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fold mntfree() into mntput_no_expire()Al Viro2013-10-241-23/+16
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* do_remount(): pull touch_mnt_namespace() upAl Viro2013-10-241-5/+1
| | | | | | ... and don't bother with dropping and regaining vfsmount_lock Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* dup_mnt_ns(): get rid of pointless grabbing of vfsmount_lockAl Viro2013-10-241-2/+0
| | | | | | mnt_list is protected by namespace_sem, not vfsmount_lock Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs_is_visible only needs namespace_sem held sharedAl Viro2013-10-241-2/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* initialize namespace_sem staticallyAl Viro2013-10-241-3/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* put_mnt_ns(): use drop_collected_mounts()Al Viro2013-10-241-5/+1
| | | | | | ... rather than open-coding it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* initmpfs: move rootfs code from fs/ramfs/ to init/Rob Landley2013-09-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | When the rootfs code was a wrapper around ramfs, having them in the same file made sense. Now that it can wrap another filesystem type, move it in with the init code instead. This also allows a subsequent patch to access rootfstype= command line arg. Signed-off-by: Rob Landley <rob@landley.net> Cc: Jeff Layton <jlayton@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Stephen Warren <swarren@nvidia.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Jim Cromie <jim.cromie@gmail.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Alexander Viro <viro@zeniv.linux.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>
* rename user_path_umountat() to user_path_mountpoint_at()Al Viro2013-09-081-1/+1
| | | | | | | ... 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>
* Merge branch 'for-linus' of ↵Linus Torvalds2013-09-071-6/+5
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs pile 2 (of many) from Al Viro: "Mostly Miklos' series this time" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: constify dcache.c inlined helpers where possible fuse: drop dentry on failed revalidate fuse: clean up return in fuse_dentry_revalidate() fuse: use d_materialise_unique() sysfs: use check_submounts_and_drop() nfs: use check_submounts_and_drop() gfs2: use check_submounts_and_drop() afs: use check_submounts_and_drop() vfs: check unlinked ancestors before mount vfs: check submounts and drop atomically vfs: add d_walk() vfs: restructure d_genocide()
| * vfs: check unlinked ancestors before mountMiklos Szeredi2013-09-051-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We check submounts before doing d_drop() on a non-empty directory dentry in NFS (have_submounts()), but we do not exclude a racing mount. Nor do we prevent mounts to be added to the disconnected subtree using relative paths after the d_drop(). This patch fixes these issues by checking for unlinked (unhashed, non-root) ancestors before proceeding with the mount. This is done with rename seqlock taken for write and with ->d_lock grabbed on each ancestor in turn, including our dentry itself. This ensures that the only one of check_submounts_and_drop() or has_unlinked_ancestor() can succeed. Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'for-linus' of ↵Linus Torvalds2013-09-071-26/+95
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull namespace changes from Eric Biederman: "This is an assorted mishmash of small cleanups, enhancements and bug fixes. The major theme is user namespace mount restrictions. nsown_capable is killed as it encourages not thinking about details that need to be considered. A very hard to hit pid namespace exiting bug was finally tracked and fixed. A couple of cleanups to the basic namespace infrastructure. Finally there is an enhancement that makes per user namespace capabilities usable as capabilities, and an enhancement that allows the per userns root to nice other processes in the user namespace" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: userns: Kill nsown_capable it makes the wrong thing easy capabilities: allow nice if we are privileged pidns: Don't have unshare(CLONE_NEWPID) imply CLONE_THREAD userns: Allow PR_CAPBSET_DROP in a user namespace. namespaces: Simplify copy_namespaces so it is clear what is going on. pidns: Fix hang in zap_pid_ns_processes by sending a potentially extra wakeup sysfs: Restrict mounting sysfs userns: Better restrictions on when proc and sysfs can be mounted vfs: Don't copy mount bind mounts of /proc/<pid>/ns/mnt between namespaces kernel/nsproxy.c: Improving a snippet of code. proc: Restrict mounting the proc filesystem vfs: Lock in place mounts from more privileged users
| * userns: Kill nsown_capable it makes the wrong thing easyEric W. Biederman2013-08-301-2/+2
| | | | | | | | | | | | | | | | | | | | nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and CAP_SETGID. For the existing users it doesn't noticably simplify things and from the suggested patches I have seen it encourages people to do the wrong thing. So remove nsown_capable. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * userns: Better restrictions on when proc and sysfs can be mountedEric W. Biederman2013-08-261-12/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rely on the fact that another flavor of the filesystem is already mounted and do not rely on state in the user namespace. Verify that the mounted filesystem is not covered in any significant way. I would love to verify that the previously mounted filesystem has no mounts on top but there are at least the directories /proc/sys/fs/binfmt_misc and /sys/fs/cgroup/ that exist explicitly for other filesystems to mount on top of. Refactor the test into a function named fs_fully_visible and call that function from the mount routines of proc and sysfs. This makes this test local to the filesystems involved and the results current of when the mounts take place, removing a weird threading of the user namespace, the mount namespace and the filesystems themselves. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * vfs: Don't copy mount bind mounts of /proc/<pid>/ns/mnt between namespacesEric W. Biederman2013-08-261-12/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Don't copy bind mounts of /proc/<pid>/ns/mnt between namespaces. These files hold references to a mount namespace and copying them between namespaces could result in a reference counting loop. The current mnt_ns_loop test prevents loops on the assumption that mounts don't cross between namespaces. Unfortunately unsharing a mount namespace and shared substrees can both cause mounts to propogate between mount namespaces. Add two flags CL_COPY_UNBINDABLE and CL_COPY_MNT_NS_FILE are added to control this behavior, and CL_COPY_ALL is redefined as both of them. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * vfs: Lock in place mounts from more privileged usersEric W. Biederman2013-07-241-0/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When creating a less privileged mount namespace or propogating mounts from a more privileged to a less privileged mount namespace lock the submounts so they may not be unmounted individually in the child mount namespace revealing what is under them. This enforces the reasonable expectation that it is not possible to see under a mount point. Most of the time mounts are on empty directories and revealing that does not matter, however I have seen an occassionaly sloppy configuration where there were interesting things concealed under a mount point that probably should not be revealed. Expirable submounts are not locked because they will eventually unmount automatically so whatever is under them already needs to be safe for unprivileged users to access. From a practical standpoint these restrictions do not appear to be significant for unprivileged users of the mount namespace. Recursive bind mounts and pivot_root continues to work, and mounts that are created in a mount namespace may be unmounted there. All of which means that the common idiom of keeping a directory of interesting files and using pivot_root to throw everything else away continues to work just fine. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | vfs: allow umount to handle mountpoints without revalidating themJeff Layton2013-09-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | VFS: collect_mounts() should return an ERR_PTRDan Carpenter2013-08-241-1/+1
|/ | | | | | | | | | | | | This should actually be returning an ERR_PTR on error instead of NULL. That was how it was designed and all the callers expect it. [AV: actually, that's what "VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors" missed - originally collect_mounts() was expected to return NULL on failure] Cc: <stable@vger.kernel.org> # 3.10+ Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* create_mnt_ns: unidiomatic use of list_add()Al Viro2013-05-041-1/+1
| | | | | | | | | | while list_add(A, B) and list_add(B, A) are equivalent when both A and B are guaranteed to be empty, the usual idiom is list_add(what, where), not the other way round... Not a bug per se, but only by accident and it makes RTFS harder for no good reason. Spotted-by: Rajat Sharma <fs.rajat@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* do_mount(): fix a leak introduced in 3.9 ("mount: consolidate permission ↵Al Viro2013-05-041-3/+2
| | | | | | | | checks") Cc: stable@vger.kernel.org Bisected-by: Michael Leun <lkml20130126@newton.leun.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'for-linus' of ↵Linus Torvalds2013-05-011-146/+195
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull VFS updates from Al Viro, Misc cleanups all over the place, mainly wrt /proc interfaces (switch create_proc_entry to proc_create(), get rid of the deprecated create_proc_read_entry() in favor of using proc_create_data() and seq_file etc). 7kloc removed. * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (204 commits) don't bother with deferred freeing of fdtables proc: Move non-public stuff from linux/proc_fs.h to fs/proc/internal.h proc: Make the PROC_I() and PDE() macros internal to procfs proc: Supply a function to remove a proc entry by PDE take cgroup_open() and cpuset_open() to fs/proc/base.c ppc: Clean up scanlog ppc: Clean up rtas_flash driver somewhat hostap: proc: Use remove_proc_subtree() drm: proc: Use remove_proc_subtree() drm: proc: Use minor->index to label things, not PDE->name drm: Constify drm_proc_list[] zoran: Don't print proc_dir_entry data in debug reiserfs: Don't access the proc_dir_entry in r_open(), r_start() r_show() proc: Supply an accessor for getting the data from a PDE's parent airo: Use remove_proc_subtree() rtl8192u: Don't need to save device proc dir PDE rtl8187se: Use a dir under /proc/net/r8180/ proc: Add proc_mkdir_data() proc: Move some bits from linux/proc_fs.h to linux/{of.h,signal.h,tty.h} proc: Move PDE_NET() to fs/proc/proc_net.c ...
| * proc: Split the namespace stuff out into linux/proc_ns.hDavid Howells2013-05-011-3/+3
| | | | | | | | | | | | | | | | | | | | Split the proc namespace stuff out into linux/proc_ns.h. Signed-off-by: David Howells <dhowells@redhat.com> cc: netdev@vger.kernel.org cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * fold release_mounts() into namespace_unlock()Al Viro2013-04-091-23/+30
| | | | | | | | | | | | | | | | | | ... and provide namespace_lock() as a trivial wrapper; switch to those two consistently. Result is patterned after rtnl_lock/rtnl_unlock pair. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * switch unlock_mount() to namespace_unlock(), convert all umount_tree() callersAl Viro2013-04-091-19/+14
| | | | | | | | | | | | | | which allows to kill the last argument of umount_tree() and make release_mounts() static. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * more conversions to namespace_unlock()Al Viro2013-04-091-14/+6
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * get rid of the second argument of shrink_submounts()Al Viro2013-04-091-4/+4
| | | | | | | | | | | | ... it's always &unmounted. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * saner umount_tree()/release_mounts(), part 1Al Viro2013-04-091-4/+13
| | | | | | | | | | | | | | | | | | global list of release_mounts() fodder, protected by namespace_sem; eventually, all umount_tree() callers will use it as kill list. Helper picking the contents of that list, releasing namespace_sem and doing release_mounts() on what it got. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * get rid of full-hash scan on detaching vfsmountsAl Viro2013-04-091-92/+137
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'for-linus' of ↵Linus Torvalds2013-04-091-1/+1
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs fixes from Al Viro: "A nasty bug in fs/namespace.c caught by Andrey + a couple of less serious unpleasantness - ecryptfs misc device playing hopeless games with try_module_get() and palinfo procfs support being... not quite correctly done, to be polite." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: mnt: release locks on error path in do_loopback palinfo fixes procfs: add proc_remove_subtree() ecryptfs: close rmmod race
| * mnt: release locks on error path in do_loopbackAndrey Vagin2013-04-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | do_loopback calls lock_mount(path) and forget to unlock_mount if clone_mnt or copy_mnt fails. [ 77.661566] ================================================ [ 77.662939] [ BUG: lock held when returning to user space! ] [ 77.664104] 3.9.0-rc5+ #17 Not tainted [ 77.664982] ------------------------------------------------ [ 77.666488] mount/514 is leaving the kernel with locks still held! [ 77.668027] 2 locks held by mount/514: [ 77.668817] #0: (&sb->s_type->i_mutex_key#7){+.+.+.}, at: [<ffffffff811cca22>] lock_mount+0x32/0xe0 [ 77.671755] #1: (&namespace_sem){+++++.}, at: [<ffffffff811cca3a>] lock_mount+0x4a/0xe0 Signed-off-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | userns: Restrict when proc and sysfs can be mountedEric W. Biederman2013-03-271-0/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Only allow unprivileged mounts of proc and sysfs if they are already mounted when the user namespace is created. proc and sysfs are interesting because they have content that is per namespace, and so fresh mounts are needed when new namespaces are created while at the same time proc and sysfs have content that is shared between every instance. Respect the policy of who may see the shared content of proc and sysfs by only allowing new mounts if there was an existing mount at the time the user namespace was created. In practice there are only two interesting cases: proc and sysfs are mounted at their usual places, proc and sysfs are not mounted at all (some form of mount namespace jail). Cc: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | vfs: Carefully propogate mounts across user namespacesEric W. Biederman2013-03-271-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As a matter of policy MNT_READONLY should not be changable if the original mounter had more privileges than creator of the mount namespace. Add the flag CL_UNPRIVILEGED to note when we are copying a mount from a mount namespace that requires more privileges to a mount namespace that requires fewer privileges. When the CL_UNPRIVILEGED flag is set cause clone_mnt to set MNT_NO_REMOUNT if any of the mnt flags that should never be changed are set. This protects both mount propagation and the initial creation of a less privileged mount namespace. Cc: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | vfs: Add a mount flag to lock read only bind mountsEric W. Biederman2013-03-271-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | When a read-only bind mount is copied from mount namespace in a higher privileged user namespace to a mount namespace in a lesser privileged user namespace, it should not be possible to remove the the read-only restriction. Add a MNT_LOCK_READONLY mount flag to indicate that a mount must remain read-only. CC: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | userns: Don't allow creation if the user is chrootedEric W. Biederman2013-03-271-0/+24
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | Guarantee that the policy of which files may be access that is established by setting the root directory will not be violated by user namespaces by verifying that the root directory points to the root of the mount namespace at the time of user namespace creation. Changing the root is a privileged operation, and as a matter of policy it serves to limit unprivileged processes to files below the current root directory. For reasons of simplicity and comprehensibility the privilege to change the root directory is gated solely on the CAP_SYS_CHROOT capability in the user namespace. Therefore when creating a user namespace we must ensure that the policy of which files may be access can not be violated by changing the root directory. Anyone who runs a processes in a chroot and would like to use user namespace can setup the same view of filesystems with a mount namespace instead. With this result that this is not a practical limitation for using user namespaces. Cc: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Reported-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* new helper: file_inode(file)Al Viro2013-02-221-1/+1
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* mount: consolidate permission checksAl Viro2013-02-221-33/+7
| | | | | | ... and ask for global CAP_SYS_ADMIN only for superblock-level remounts Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* get rid of unprotected dereferencing of mnt->mnt_nsAl Viro2013-02-221-12/+17
| | | | | | | | | | It's safe only under namespace_sem or vfsmount_lock; all places in fs/namespace.c that want mnt->mnt_ns->user_ns actually want to use current->nsproxy->mnt_ns->user_ns (note the calls of check_mnt() in there). Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs, freeze: use ACCESS_ONCE() to guard access to ->mnt_flagsMiao Xie2012-12-201-1/+1
| | | | | | | | The compiler may optimize the while loop and make the check just be done once, so we should use ACCESS_ONCE() to guard access to ->mnt_flags Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* userns: Require CAP_SYS_ADMIN for most uses of setns.Eric W. Biederman2012-12-141-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andy Lutomirski <luto@amacapital.net> found a nasty little bug in the permissions of setns. With unprivileged user namespaces it became possible to create new namespaces without privilege. However the setns calls were relaxed to only require CAP_SYS_ADMIN in the user nameapce of the targed namespace. Which made the following nasty sequence possible. pid = clone(CLONE_NEWUSER | CLONE_NEWNS); if (pid == 0) { /* child */ system("mount --bind /home/me/passwd /etc/passwd"); } else if (pid != 0) { /* parent */ char path[PATH_MAX]; snprintf(path, sizeof(path), "/proc/%u/ns/mnt"); fd = open(path, O_RDONLY); setns(fd, 0); system("su -"); } Prevent this possibility by requiring CAP_SYS_ADMIN in the current user namespace when joing all but the user namespace. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* proc: Usable inode numbers for the namespace file descriptors.Eric W. Biederman2012-11-201-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: fix return value on mntns_install() failureZhao Hongjiang2012-11-191-1/+1
| | | | | | | Change return value from -EINVAL to -EPERM when the permission check fails. Signed-off-by: Zhao Hongjiang <zhaohongjiang@huawei.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* vfs: Allow unprivileged manipulation of the mount namespace.Eric W. Biederman2012-11-191-26/+43
| | | | | | | | | | | | | | | | - Add a filesystem flag to mark filesystems that are safe to mount as an unprivileged user. - Add a filesystem flag to mark filesystems that don't need MNT_NODEV when mounted by an unprivileged user. - Relax the permission checks to allow unprivileged users that have CAP_SYS_ADMIN permissions in the user namespace referred to by the current mount namespace to be allowed to mount, unmount, and move filesystems. Acked-by: "Serge E. Hallyn" <serge@hallyn.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* vfs: Only support slave subtrees across different user namespacesEric W. Biederman2012-11-191-3/+8
| | | | | | | | | | | | Sharing mount subtress with mount namespaces created by unprivileged users allows unprivileged mounts created by unprivileged users to propagate to mount namespaces controlled by privileged users. Prevent nasty consequences by changing shared subtrees to slave subtress when an unprivileged users creates a new mount namespace. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-10 08:50:19 +0000