Inotify was switched to use anon_inode instead of its own private filesystem
which only had one inode in commit c44dcc56d2 "switch inotify_user to
anon_inode"
The problem with this is that now the inotify inode is not a distinct inode
which can be managed by LSMs. userspace tools which use inotify were allowed
to use the inotify inode but may not have had permission to do read/write type
operations on the anon_inode. After looking at the anon_inode and its users
it looks like the best solution is to just mark the anon_inode as S_PRIVATE
so the security system will ignore it.
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pull ACC_MODE to fs.h; we have several copies all over the place
* nightmarish expression calculating f_mode by f_flags deserves a helper
too (OPEN_FMODE(flags))
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
It seems a couple places such as arch/ia64/kernel/perfmon.c and
drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile()
instead of a private pseudo-fs + alloc_file(), if only there were a way
to get a read-only file. So provide this by having anon_inode_getfile()
create a read-only file if we pass O_RDONLY in flags.
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Filesystems outside the regular namespace do not have to clear DCACHE_UNHASHED
in order to have a working /proc/$pid/fd/XXX. Nothing in proc prevents the
fd link from being used if its dentry is not in the hash.
Also, it does not get put into the dcache hash if DCACHE_UNHASHED is clear;
that depends on the filesystem calling d_add or d_rehash.
So delete the misleading comments and needless code.
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add a d_dname method for anon_inodes filesystem, the same way pipefs and
sockfs pseudo filesystems. This allows us to remove the DCACHE_UNHASHED
hack from anon_inodes.c (see next patch).
[AV: inumber is useless here, dropped from anon_inodefs_dname()]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split the anonfd interface into a bare file pointer creation one, and a
file pointer creation plus install one.
There are cases, like the usage of eventfds inside other kernel
interfaces, where the file pointer created by anonfd needs to be used
inside the initialization of other structures.
As it is right now, as soon as anon_inode_getfd() returns, the kenrle can
race with userspace closing the newly installed file descriptor.
This patch, while keeping the old anon_inode_getfd(), introduces a new
anon_inode_getfile() (whose services are reused in anon_inode_getfd())
that allows to split the file creation phase and the fd install one.
Once all the kernel structures are initialized, the code can call the
proper fd_install().
Gregory manifested the need for something like this inside KVM.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Gregory Haskins <ghaskins@novell.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
.set_page_dirty() is one of those a_ops that defaults to the
buffer implementation when not set. Therefore provide a dummy
function to make it do nothing.
(Uncovered by perfcounters fd's which can now be writable-mmap-ed.)
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There is an imbalance for anonymous inodes. If the fops->owner field is set,
the module reference count of owner is decreases on release.
("filp_close" --> "__fput" ---> "fops_put")
On the other hand, anon_inode_getfd does not increase the module reference
count of owner. This causes two problems:
- if owner is set, the module refcount goes negative
- if owner is not set, the module can be unloaded while code is running
This patch changes anon_inode_getfd to be symmetric regarding fops->owner
handling.
I have checked all existing users of anon_inode_getfd. Noone sets fops->owner,
thats why nobody has seen the module refcount negative. The refcounting was
tested with a patched and unpatched KVM module.(see patch 2/2) I also did an
epoll_open/close test.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Avi Kivity <avi@redhat.com>
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>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Morris <jmorris@namei.org>
Building on the previous change to anon_inode_getfd, this patch introduces
support for handling of O_NONBLOCK in addition to the already supported
O_CLOEXEC. Following patches will take advantage of this support. As can be
seen, the additional support for supporting this functionality is minimal.
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch just extends the anon_inode_getfd interface to take an additional
parameter with a flag value. The flag value is passed on to
get_unused_fd_flags in anticipation for a use with the O_CLOEXEC flag.
No actual semantic changes here, the changed callers all pass 0 for now.
[akpm@linux-foundation.org: KVM fix]
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
a) none of the callers even looks at inode or file returned by anon_inode_getfd()
b) any caller that would try to look at those would be racy, since by the time
it returns we might have raced with close() from another thread and that
file would be pining for fjords.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Some new uses of get_empty_filp() have crept in; switched
to alloc_file() to make sure that pieces of initialization
won't be missing.
We really need to kill get_empty_filp().
[AV] fixed dentry leak on failure exit in anon_inode_getfd()
Cc: Erez Zadok <ezk@cs.sunysb.edu>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J Bruce Fields" <bfields@fieldses.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since we know the shared inode count is always >0, we can avoid igrab()
and use an open coded atomic_inc().
This also fixes a bug noticed by Yan Zheng <yanzheng@21cn.com>: were checking
for an IS_ERR() return from igrab(), but it actually returns NULL on error.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Yan Zheng <yanzheng@21cn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kvm uses a pseudo filesystem, kvmfs, to generate inodes, a job that the
new anonymous inodes source does much better.
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This patch add an anonymous inode source, to be used for files that need
and inode only in order to create a file*. We do not care of having an
inode for each file, and we do not even care of having different names in
the associated dentries (dentry names will be same for classes of file*).
This allow code reuse, and will be used by epoll, signalfd and timerfd
(and whatever else there'll be).
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Paris