linux-stable.git/fs/proc/proc_sysctl.c, branch v3.16.40

sysctl: Drop reference added by grab_header in proc_sys_readdir

2017-02-23T03:54:47+00:00

commit 93362fa47fe98b62e4a34ab408c4a418432e7939 upstream.

Fixes CVE-2016-9191, proc_sys_readdir doesn't drop reference
added by grab_header when return from !dir_emit_dots path.
It can cause any path called unregister_sysctl_table will
wait forever.

The calltrace of CVE-2016-9191:

[ 5535.960522] Call Trace:
[ 5535.963265]  [] schedule+0x3f/0xa0
[ 5535.968817]  [] schedule_timeout+0x3db/0x6f0
[ 5535.975346]  [] ? wait_for_completion+0x45/0x130
[ 5535.982256]  [] wait_for_completion+0xc3/0x130
[ 5535.988972]  [] ? wake_up_q+0x80/0x80
[ 5535.994804]  [] drop_sysctl_table+0xc4/0xe0
[ 5536.001227]  [] drop_sysctl_table+0x77/0xe0
[ 5536.007648]  [] unregister_sysctl_table+0x4d/0xa0
[ 5536.014654]  [] unregister_sysctl_table+0x7f/0xa0
[ 5536.021657]  [] unregister_sched_domain_sysctl+0x15/0x40
[ 5536.029344]  [] partition_sched_domains+0x44/0x450
[ 5536.036447]  [] ? __mutex_unlock_slowpath+0x111/0x1f0
[ 5536.043844]  [] rebuild_sched_domains_locked+0x64/0xb0
[ 5536.051336]  [] update_flag+0x11d/0x210
[ 5536.057373]  [] ? mutex_lock_nested+0x2df/0x450
[ 5536.064186]  [] ? cpuset_css_offline+0x1b/0x60
[ 5536.070899]  [] ? trace_hardirqs_on+0xd/0x10
[ 5536.077420]  [] ? mutex_lock_nested+0x2df/0x450
[ 5536.084234]  [] ? css_killed_work_fn+0x25/0x220
[ 5536.091049]  [] cpuset_css_offline+0x35/0x60
[ 5536.097571]  [] css_killed_work_fn+0x5c/0x220
[ 5536.104207]  [] process_one_work+0x1df/0x710
[ 5536.110736]  [] ? process_one_work+0x160/0x710
[ 5536.117461]  [] worker_thread+0x12b/0x4a0
[ 5536.123697]  [] ? process_one_work+0x710/0x710
[ 5536.130426]  [] kthread+0xfe/0x120
[ 5536.135991]  [] ret_from_fork+0x1f/0x40
[ 5536.142041]  [] ? kthread_create_on_node+0x230/0x230

One cgroup maintainer mentioned that "cgroup is trying to offline
a cpuset css, which takes place under cgroup_mutex.  The offlining
ends up trying to drain active usages of a sysctl table which apprently
is not happening."
The real reason is that proc_sys_readdir doesn't drop reference added
by grab_header when return from !dir_emit_dots path. So this cpuset
offline path will wait here forever.

See here for details: http://www.openwall.com/lists/oss-security/2016/11/04/13

Fixes: f0c3b5093add ("[readdir] convert procfs")
Reported-by: CAI Qian 
Tested-by: Yang Shukui 
Signed-off-by: Zhou Chengming 
Acked-by: Al Viro 
Signed-off-by: Eric W. Biederman 
Signed-off-by: Ben Hutchings

fs: Give dentry to inode_change_ok() instead of inode

2017-02-23T03:53:52+00:00

commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.

inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Jan Kara 
[bwh: Backported to 3.16:
 - Drop changes to orangefs, overlayfs
 - Adjust filenames, context
 - In nfsd, pass dentry to nfsd_sanitize_attrs()
 - Update ext3 as well]
Signed-off-by: Ben Hutchings

Revert "fs: Give dentry to inode_change_ok() instead of inode"

2017-02-23T03:53:52+00:00

This reverts commit be9df699432235753c3824b0f5a27d46de7fdc9e, which was
commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.  The backport
breaks fuse and makes a mess of xfs, which can be improved by picking
further upstream commits as I should have done in the first place.

Signed-off-by: Ben Hutchings

fs: Give dentry to inode_change_ok() instead of inode

2016-11-20T01:17:38+00:00

commit 31051c85b5e2aaaf6315f74c72a732673632a905 upstream.

inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Jan Kara 
[bwh: Backported to 3.16:
 - Drop changes to orangefs, overlayfs
 - Adjust filenames, context
 - In fuse, pass dentry to fuse_do_setattr()
 - In nfsd, pass dentry to nfsd_sanitize_attrs()
 - In xfs, pass dentry to xfs_setattr_nonsize() and xfs_setattr_size()
 - Update ext3 as well]
Signed-off-by: Ben Hutchings

sysctl: Allow creating permanently empty directories that serve as mountpoints.

2015-07-15T09:01:06+00:00

commit f9bd6733d3f11e24f3949becf277507d422ee1eb upstream.

Add a magic sysctl table sysctl_mount_point that when used to
create a directory forces that directory to be permanently empty.

Update the code to use make_empty_dir_inode when accessing permanently
empty directories.

Update the code to not allow adding to permanently empty directories.

Update /proc/sys/fs/binfmt_misc to be a permanently empty directory.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Luis Henriques

Don't pass inode to ->d_hash() and ->d_compare()

2013-06-29T08:57:36+00:00

Instances either don't look at it at all (the majority of cases) or
only want it to find the superblock (which can be had as dentry->d_sb).
A few cases that want more are actually safe with dentry->d_inode -
the only precaution needed is the check that it hadn't been replaced with
NULL by rmdir() or by overwriting rename(), which case should be simply
treated as cache miss.

Signed-off-by: Linus Torvalds 
Signed-off-by: Al Viro

[readdir] convert procfs

2013-06-29T08:56:32+00:00

Signed-off-by: Al Viro

fs/proc: clean up printks

2013-02-28T03:10:11+00:00

- use pr_foo() throughout

- remove a couple of duplicated KERN_WARNINGs, via WARN(KERN_WARNING "...")

- nuke a few warnings which I've never seen happen, ever.

Cc: Joe Perches 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

new helper: file_inode(file)

2013-02-23T04:31:31+00:00

Signed-off-by: Al Viro

procfs: drop vmtruncate

2012-12-20T19:00:01+00:00

Removed vmtruncate

Signed-off-by: Marco Stornelli 
Signed-off-by: Al Viro