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* nsfs: Simplify __ns_get_pathEric W. Biederman2016-09-221-5/+2
| | | | | | | | | | | Move mntget from the very beginning of __ns_get_path to the success path of __ns_get_path, and remove the mntget calls. This removes the possibility that there will be a mntget/mntput pair of __ns_get_path has to retry, and generally simplifies the code. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* nsfs: add ioctl to get a parent namespaceAndrey Vagin2016-09-221-0/+4
| | | | | | | | | | | | Pid and user namepaces are hierarchical. There is no way to discover parent-child relationships. In a future we will use this interface to dump and restore nested namespaces. Acked-by: Serge Hallyn <serge@hallyn.com> Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* nsfs: add ioctl to get an owning user namespace for ns file descriptorAndrey Vagin2016-09-221-13/+83
| | | | | | | | | | | | | | | | | | | | | | | | | | Each namespace has an owning user namespace and now there is not way to discover these relationships. Understending namespaces relationships allows to answer the question: what capability does process X have to perform operations on a resource governed by namespace Y? After a long discussion, Eric W. Biederman proposed to use ioctl-s for this purpose. The NS_GET_USERNS ioctl returns a file descriptor to an owning user namespace. It returns EPERM if a target namespace is outside of a current user namespace. v2: rename parent to relative v3: Add a missing mntput when returning -EAGAIN --EWB Acked-by: Serge Hallyn <serge@hallyn.com> Link: https://lkml.org/lkml/2016/7/6/158 Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* fs/seq_file: convert int seq_vprint/seq_printf/etc... returns to voidJoe Perches2015-09-111-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The seq_<foo> function return values were frequently misused. See: commit 1f33c41c03da ("seq_file: Rename seq_overflow() to seq_has_overflowed() and make public") All uses of these return values have been removed, so convert the return types to void. Miscellanea: o Move seq_put_decimal_<type> and seq_escape prototypes closer the other seq_vprintf prototypes o Reorder seq_putc and seq_puts to return early on overflow o Add argument names to seq_vprintf and seq_printf o Update the seq_escape kernel-doc o Convert a couple of leading spaces to tabs in seq_escape Signed-off-by: Joe Perches <joe@perches.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mark Brown <broonie@kernel.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Joerg Roedel <jroedel@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* nsfs: Add a show_path method to fix mountinfoEric W. Biederman2015-07-111-0/+10
| | | | | | | | | Today mountinfo displays a very unhelpful "/" for nsfs files. Add a show_path method returning the same string as ns_dname. This results in a bind mount of /proc/<pid>/ns/net showing up in /proc/<pid>/mountinfo as "net:[1234...]" instead of "/". Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* VFS: assorted weird filesystems: d_inode() annotationsDavid Howells2015-04-151-2/+2
| | | | | Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* take the targets of /proc/*/ns/* symlinks to separate fsAl Viro2014-12-101-0/+161
New pseudo-filesystem: nsfs. Targets of /proc/*/ns/* live there now. It's not mountable (not even registered, so it's not in /proc/filesystems, etc.). Files on it *are* bindable - we explicitly permit that in do_loopback(). This stuff lives in fs/nsfs.c now; proc_ns_fget() moved there as well. get_proc_ns() is a macro now (it's simply returning ->i_private; would have been an inline, if not for header ordering headache). proc_ns_inode() is an ex-parrot. The interface used in procfs is ns_get_path(path, task, ops) and ns_get_name(buf, size, task, ops). Dentries and inodes are never hashed; a non-counting reference to dentry is stashed in ns_common (removed by ->d_prune()) and reused by ns_get_path() if present. See ns_get_path()/ns_prune_dentry/nsfs_evict() for details of that mechanism. As the result, proc_ns_follow_link() has stopped poking in nd->path.mnt; it does nd_jump_link() on a consistent <vfsmount,dentry> pair it gets from ns_get_path(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>