License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
|
|
|
/* SPDX-License-Identifier: GPL-2.0 */
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
|
|
|
|
*
|
|
|
|
|
* Definitions for mount interface. This describes the in the kernel build
|
|
|
|
|
* linkedlist with mounted filesystems.
|
|
|
|
|
*
|
|
|
|
|
* Author: Marco van Wieringen <mvw@planets.elm.net>
|
|
|
|
|
*
|
|
|
|
|
*/
|
|
|
|
|
#ifndef _LINUX_MOUNT_H
|
|
|
|
|
#define _LINUX_MOUNT_H
|
|
|
|
|
|
2005-07-13 04:58:07 +08:00
|
|
|
#include <linux/types.h>
|
2005-04-17 06:20:36 +08:00
|
|
|
#include <linux/list.h>
|
[PATCH] r/o bind mounts: track numbers of writers to mounts
This is the real meat of the entire series. It actually
implements the tracking of the number of writers to a mount.
However, it causes scalability problems because there can be
hundreds of cpus doing open()/close() on files on the same mnt at
the same time. Even an atomic_t in the mnt has massive scalaing
problems because the cacheline gets so terribly contended.
This uses a statically-allocated percpu variable. All want/drop
operations are local to a cpu as long that cpu operates on the same
mount, and there are no writer count imbalances. Writer count
imbalances happen when a write is taken on one cpu, and released
on another, like when an open/close pair is performed on two
Upon a remount,ro request, all of the data from the percpu
variables is collected (expensive, but very rare) and we determine
if there are any outstanding writers to the mount.
I've written a little benchmark to sit in a loop for a couple of
seconds in several cpus in parallel doing open/write/close loops.
http://sr71.net/~dave/linux/openbench.c
The code in here is a a worst-possible case for this patch. It
does opens on a _pair_ of files in two different mounts in parallel.
This should cause my code to lose its "operate on the same mount"
optimization completely. This worst-case scenario causes a 3%
degredation in the benchmark.
I could probably get rid of even this 3%, but it would be more
complex than what I have here, and I think this is getting into
acceptable territory. In practice, I expect writing more than 3
bytes to a file, as well as disk I/O to mask any effects that this
has.
(To get rid of that 3%, we could have an #defined number of mounts
in the percpu variable. So, instead of a CPU getting operate only
on percpu data when it accesses only one mount, it could stay on
percpu data when it only accesses N or fewer mounts.)
[AV] merged fix for __clear_mnt_mount() stepping on freed vfsmount
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-02-16 06:37:59 +08:00
|
|
|
#include <linux/nodemask.h>
|
2005-04-17 06:20:36 +08:00
|
|
|
#include <linux/spinlock.h>
|
fs: scale mntget/mntput
The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.
The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.
We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.
- check the global sum once every interval (this will delay zero detection
for some interval, so it's probably a showstopper for vfsmounts).
- keep a local count and only taking the global sum when local reaches 0 (this
is difficult for vfsmounts, because we can't hold preempt off for the life of
a reference, so a counter would need to be per-thread or tied strongly to a
particular CPU which requires more locking).
- keep a local difference of increments and decrements, which allows us to sum
the total difference and hence find the refcount when summing all CPUs. Then,
keep a single integer "long" refcount for slow and long lasting references,
and only take the global sum of local counters when the long refcount is 0.
This last scheme is what I implemented here. Attached mounts and process root
and working directory references are "long" references, and everything else is
a short reference.
This allows scalable vfsmount references during path walking over mounted
subtrees and unattached (lazy umounted) mounts with processes still running
in them.
This results in one fewer atomic op in the fastpath: mntget is now just a
per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock
and non-atomic decrement in the common case. However code is otherwise bigger
and heavier, so single threaded performance is basically a wash.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 14:50:11 +08:00
|
|
|
#include <linux/seqlock.h>
|
2011-07-27 07:09:06 +08:00
|
|
|
#include <linux/atomic.h>
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2006-06-23 17:02:58 +08:00
|
|
|
struct super_block;
|
|
|
|
|
struct vfsmount;
|
|
|
|
|
struct dentry;
|
2006-12-08 18:37:56 +08:00
|
|
|
struct mnt_namespace;
|
2018-11-04 19:48:34 +08:00
|
|
|
struct fs_context;
|
2006-06-23 17:02:58 +08:00
|
|
|
|
2005-11-08 06:19:07 +08:00
|
|
|
#define MNT_NOSUID 0x01
|
|
|
|
|
#define MNT_NODEV 0x02
|
|
|
|
|
#define MNT_NOEXEC 0x04
|
2006-01-10 12:52:17 +08:00
|
|
|
#define MNT_NOATIME 0x08
|
|
|
|
|
#define MNT_NODIRATIME 0x10
|
2006-12-13 16:34:34 +08:00
|
|
|
#define MNT_RELATIME 0x20
|
2008-02-16 06:38:00 +08:00
|
|
|
#define MNT_READONLY 0x40 /* does the user want this to be r/o? */
|
2020-08-28 01:09:46 +08:00
|
|
|
#define MNT_NOSYMFOLLOW 0x80
|
2006-01-08 17:03:19 +08:00
|
|
|
|
2006-06-09 21:34:17 +08:00
|
|
|
#define MNT_SHRINKABLE 0x100
|
2009-04-26 18:25:54 +08:00
|
|
|
#define MNT_WRITE_HOLD 0x200
|
2006-06-09 21:34:17 +08:00
|
|
|
|
2006-01-10 12:52:17 +08:00
|
|
|
#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
|
|
|
|
|
#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
|
2010-01-27 03:20:47 +08:00
|
|
|
/*
|
|
|
|
|
* MNT_SHARED_MASK is the set of flags that should be cleared when a
|
|
|
|
|
* mount becomes shared. Currently, this is only the flag that says a
|
|
|
|
|
* mount cannot be bind mounted, since this is how we create a mount
|
|
|
|
|
* that shares events with another mount. If you add a new MNT_*
|
|
|
|
|
* flag, consider how it interacts with shared mounts.
|
|
|
|
|
*/
|
|
|
|
|
#define MNT_SHARED_MASK (MNT_UNBINDABLE)
|
2014-07-29 07:26:53 +08:00
|
|
|
#define MNT_USER_SETTABLE_MASK (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
|
|
|
|
|
| MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
|
2020-08-28 01:09:46 +08:00
|
|
|
| MNT_READONLY | MNT_NOSYMFOLLOW)
|
mnt: Correct permission checks in do_remount
While invesgiating the issue where in "mount --bind -oremount,ro ..."
would result in later "mount --bind -oremount,rw" succeeding even if
the mount started off locked I realized that there are several
additional mount flags that should be locked and are not.
In particular MNT_NOSUID, MNT_NODEV, MNT_NOEXEC, and the atime
flags in addition to MNT_READONLY should all be locked. These
flags are all per superblock, can all be changed with MS_BIND,
and should not be changable if set by a more privileged user.
The following additions to the current logic are added in this patch.
- nosuid may not be clearable by a less privileged user.
- nodev may not be clearable by a less privielged user.
- noexec may not be clearable by a less privileged user.
- atime flags may not be changeable by a less privileged user.
The logic with atime is that always setting atime on access is a
global policy and backup software and auditing software could break if
atime bits are not updated (when they are configured to be updated),
and serious performance degradation could result (DOS attack) if atime
updates happen when they have been explicitly disabled. Therefore an
unprivileged user should not be able to mess with the atime bits set
by a more privileged user.
The additional restrictions are implemented with the addition of
MNT_LOCK_NOSUID, MNT_LOCK_NODEV, MNT_LOCK_NOEXEC, and MNT_LOCK_ATIME
mnt flags.
Taken together these changes and the fixes for MNT_LOCK_READONLY
should make it safe for an unprivileged user to create a user
namespace and to call "mount --bind -o remount,... ..." without
the danger of mount flags being changed maliciously.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2014-07-29 08:26:07 +08:00
|
|
|
#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
|
2010-01-27 03:20:47 +08:00
|
|
|
|
smarter propagate_mnt()
The current mainline has copies propagated to *all* nodes, then
tears down the copies we made for nodes that do not contain
counterparts of the desired mountpoint. That sets the right
propagation graph for the copies (at teardown time we move
the slaves of removed node to a surviving peer or directly
to master), but we end up paying a fairly steep price in
useless allocations. It's fairly easy to create a situation
where N calls of mount(2) create exactly N bindings, with
O(N^2) vfsmounts allocated and freed in process.
Fortunately, it is possible to avoid those allocations/freeings.
The trick is to create copies in the right order and find which
one would've eventually become a master with the current algorithm.
It turns out to be possible in O(nodes getting propagation) time
and with no extra allocations at all.
One part is that we need to make sure that eventual master will be
created before its slaves, so we need to walk the propagation
tree in a different order - by peer groups. And iterate through
the peers before dealing with the next group.
Another thing is finding the (earlier) copy that will be a master
of one we are about to create; to do that we are (temporary) marking
the masters of mountpoints we are attaching the copies to.
Either we are in a peer of the last mountpoint we'd dealt with,
or we have the following situation: we are attaching to mountpoint M,
the last copy S_0 had been attached to M_0 and there are sequences
S_0...S_n, M_0...M_n such that S_{i+1} is a master of S_{i},
S_{i} mounted on M{i} and we need to create a slave of the first S_{k}
such that M is getting propagation from M_{k}. It means that the master
of M_{k} will be among the sequence of masters of M. On the
other hand, the nearest marked node in that sequence will either
be the master of M_{k} or the master of M_{k-1} (the latter -
in the case if M_{k-1} is a slave of something M gets propagation
from, but in a wrong peer group).
So we go through the sequence of masters of M until we find
a marked one (P). Let N be the one before it. Then we go through
the sequence of masters of S_0 until we find one (say, S) mounted
on a node D that has P as master and check if D is a peer of N.
If it is, S will be the master of new copy, if not - the master of S
will be.
That's it for the hard part; the rest is fairly simple. Iterator
is in next_group(), handling of one prospective mountpoint is
propagate_one().
It seems to survive all tests and gives a noticably better performance
than the current mainline for setups that are seriously using shared
subtrees.
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-02-27 22:35:45 +08:00
|
|
|
#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
|
2020-05-14 22:44:24 +08:00
|
|
|
MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED | \
|
|
|
|
|
MNT_CURSOR)
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2010-02-05 22:30:46 +08:00
|
|
|
#define MNT_INTERNAL 0x4000
|
2005-04-17 06:20:36 +08:00
|
|
|
|
mnt: Correct permission checks in do_remount
While invesgiating the issue where in "mount --bind -oremount,ro ..."
would result in later "mount --bind -oremount,rw" succeeding even if
the mount started off locked I realized that there are several
additional mount flags that should be locked and are not.
In particular MNT_NOSUID, MNT_NODEV, MNT_NOEXEC, and the atime
flags in addition to MNT_READONLY should all be locked. These
flags are all per superblock, can all be changed with MS_BIND,
and should not be changable if set by a more privileged user.
The following additions to the current logic are added in this patch.
- nosuid may not be clearable by a less privileged user.
- nodev may not be clearable by a less privielged user.
- noexec may not be clearable by a less privileged user.
- atime flags may not be changeable by a less privileged user.
The logic with atime is that always setting atime on access is a
global policy and backup software and auditing software could break if
atime bits are not updated (when they are configured to be updated),
and serious performance degradation could result (DOS attack) if atime
updates happen when they have been explicitly disabled. Therefore an
unprivileged user should not be able to mess with the atime bits set
by a more privileged user.
The additional restrictions are implemented with the addition of
MNT_LOCK_NOSUID, MNT_LOCK_NODEV, MNT_LOCK_NOEXEC, and MNT_LOCK_ATIME
mnt flags.
Taken together these changes and the fixes for MNT_LOCK_READONLY
should make it safe for an unprivileged user to create a user
namespace and to call "mount --bind -o remount,... ..." without
the danger of mount flags being changed maliciously.
Cc: stable@vger.kernel.org
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2014-07-29 08:26:07 +08:00
|
|
|
#define MNT_LOCK_ATIME 0x040000
|
|
|
|
|
#define MNT_LOCK_NOEXEC 0x080000
|
|
|
|
|
#define MNT_LOCK_NOSUID 0x100000
|
|
|
|
|
#define MNT_LOCK_NODEV 0x200000
|
2013-03-22 18:10:15 +08:00
|
|
|
#define MNT_LOCK_READONLY 0x400000
|
2013-03-30 12:04:39 +08:00
|
|
|
#define MNT_LOCKED 0x800000
|
2013-09-30 10:06:07 +08:00
|
|
|
#define MNT_DOOMED 0x1000000
|
|
|
|
|
#define MNT_SYNC_UMOUNT 0x2000000
|
smarter propagate_mnt()
The current mainline has copies propagated to *all* nodes, then
tears down the copies we made for nodes that do not contain
counterparts of the desired mountpoint. That sets the right
propagation graph for the copies (at teardown time we move
the slaves of removed node to a surviving peer or directly
to master), but we end up paying a fairly steep price in
useless allocations. It's fairly easy to create a situation
where N calls of mount(2) create exactly N bindings, with
O(N^2) vfsmounts allocated and freed in process.
Fortunately, it is possible to avoid those allocations/freeings.
The trick is to create copies in the right order and find which
one would've eventually become a master with the current algorithm.
It turns out to be possible in O(nodes getting propagation) time
and with no extra allocations at all.
One part is that we need to make sure that eventual master will be
created before its slaves, so we need to walk the propagation
tree in a different order - by peer groups. And iterate through
the peers before dealing with the next group.
Another thing is finding the (earlier) copy that will be a master
of one we are about to create; to do that we are (temporary) marking
the masters of mountpoints we are attaching the copies to.
Either we are in a peer of the last mountpoint we'd dealt with,
or we have the following situation: we are attaching to mountpoint M,
the last copy S_0 had been attached to M_0 and there are sequences
S_0...S_n, M_0...M_n such that S_{i+1} is a master of S_{i},
S_{i} mounted on M{i} and we need to create a slave of the first S_{k}
such that M is getting propagation from M_{k}. It means that the master
of M_{k} will be among the sequence of masters of M. On the
other hand, the nearest marked node in that sequence will either
be the master of M_{k} or the master of M_{k-1} (the latter -
in the case if M_{k-1} is a slave of something M gets propagation
from, but in a wrong peer group).
So we go through the sequence of masters of M until we find
a marked one (P). Let N be the one before it. Then we go through
the sequence of masters of S_0 until we find one (say, S) mounted
on a node D that has P as master and check if D is a peer of N.
If it is, S will be the master of new copy, if not - the master of S
will be.
That's it for the hard part; the rest is fairly simple. Iterator
is in next_group(), handling of one prospective mountpoint is
propagate_one().
It seems to survive all tests and gives a noticably better performance
than the current mainline for setups that are seriously using shared
subtrees.
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-02-27 22:35:45 +08:00
|
|
|
#define MNT_MARKED 0x4000000
|
2014-12-23 08:30:08 +08:00
|
|
|
#define MNT_UMOUNT 0x8000000
|
2020-05-14 22:44:24 +08:00
|
|
|
#define MNT_CURSOR 0x10000000
|
2013-03-22 18:10:15 +08:00
|
|
|
|
2005-11-08 06:19:07 +08:00
|
|
|
struct vfsmount {
|
2005-04-17 06:20:36 +08:00
|
|
|
struct dentry *mnt_root; /* root of the mounted tree */
|
|
|
|
|
struct super_block *mnt_sb; /* pointer to superblock */
|
|
|
|
|
int mnt_flags;
|
2021-01-21 21:19:20 +08:00
|
|
|
struct user_namespace *mnt_userns;
|
2016-10-28 16:22:25 +08:00
|
|
|
} __randomize_layout;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2021-01-21 21:19:20 +08:00
|
|
|
static inline struct user_namespace *mnt_user_ns(const struct vfsmount *mnt)
|
|
|
|
|
{
|
2021-01-21 21:19:54 +08:00
|
|
|
/* Pairs with smp_store_release() in do_idmap_mount(). */
|
|
|
|
|
return smp_load_acquire(&mnt->mnt_userns);
|
2021-01-21 21:19:20 +08:00
|
|
|
}
|
|
|
|
|
|
2009-04-26 18:25:55 +08:00
|
|
|
struct file; /* forward dec */
|
2014-08-07 21:12:31 +08:00
|
|
|
struct path;
|
2009-04-26 18:25:55 +08:00
|
|
|
|
2008-02-16 06:37:30 +08:00
|
|
|
extern int mnt_want_write(struct vfsmount *mnt);
|
2009-04-26 18:25:55 +08:00
|
|
|
extern int mnt_want_write_file(struct file *file);
|
2008-02-16 06:37:30 +08:00
|
|
|
extern void mnt_drop_write(struct vfsmount *mnt);
|
2011-12-09 21:06:57 +08:00
|
|
|
extern void mnt_drop_write_file(struct file *file);
|
fs: scale mntget/mntput
The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.
The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.
We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.
- check the global sum once every interval (this will delay zero detection
for some interval, so it's probably a showstopper for vfsmounts).
- keep a local count and only taking the global sum when local reaches 0 (this
is difficult for vfsmounts, because we can't hold preempt off for the life of
a reference, so a counter would need to be per-thread or tied strongly to a
particular CPU which requires more locking).
- keep a local difference of increments and decrements, which allows us to sum
the total difference and hence find the refcount when summing all CPUs. Then,
keep a single integer "long" refcount for slow and long lasting references,
and only take the global sum of local counters when the long refcount is 0.
This last scheme is what I implemented here. Attached mounts and process root
and working directory references are "long" references, and everything else is
a short reference.
This allows scalable vfsmount references during path walking over mounted
subtrees and unattached (lazy umounted) mounts with processes still running
in them.
This results in one fewer atomic op in the fastpath: mntget is now just a
per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock
and non-atomic decrement in the common case. However code is otherwise bigger
and heavier, so single threaded performance is basically a wash.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07 14:50:11 +08:00
|
|
|
extern void mntput(struct vfsmount *mnt);
|
|
|
|
|
extern struct vfsmount *mntget(struct vfsmount *mnt);
|
2016-11-21 08:45:28 +08:00
|
|
|
extern struct vfsmount *mnt_clone_internal(const struct path *path);
|
2018-11-02 07:07:25 +08:00
|
|
|
extern bool __mnt_is_readonly(struct vfsmount *mnt);
|
fs: Treat foreign mounts as nosuid
If a process gets access to a mount from a different user
namespace, that process should not be able to take advantage of
setuid files or selinux entrypoints from that filesystem. Prevent
this by treating mounts from other mount namespaces and those not
owned by current_user_ns() or an ancestor as nosuid.
This will make it safer to allow more complex filesystems to be
mounted in non-root user namespaces.
This does not remove the need for MNT_LOCK_NOSUID. The setuid,
setgid, and file capability bits can no longer be abused if code in
a user namespace were to clear nosuid on an untrusted filesystem,
but this patch, by itself, is insufficient to protect the system
from abuse of files that, when execed, would increase MAC privilege.
As a more concrete explanation, any task that can manipulate a
vfsmount associated with a given user namespace already has
capabilities in that namespace and all of its descendents. If they
can cause a malicious setuid, setgid, or file-caps executable to
appear in that mount, then that executable will only allow them to
elevate privileges in exactly the set of namespaces in which they
are already privileges.
On the other hand, if they can cause a malicious executable to
appear with a dangerous MAC label, running it could change the
caller's security context in a way that should not have been
possible, even inside the namespace in which the task is confined.
As a hardening measure, this would have made CVE-2014-5207 much
more difficult to exploit.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: James Morris <james.l.morris@oracle.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2016-06-24 05:41:05 +08:00
|
|
|
extern bool mnt_may_suid(struct vfsmount *mnt);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2014-10-24 06:14:36 +08:00
|
|
|
struct path;
|
2016-11-21 08:45:28 +08:00
|
|
|
extern struct vfsmount *clone_private_mount(const struct path *path);
|
2019-04-05 09:04:13 +08:00
|
|
|
extern int __mnt_want_write(struct vfsmount *);
|
|
|
|
|
extern void __mnt_drop_write(struct vfsmount *);
|
2014-10-24 06:14:36 +08:00
|
|
|
|
2006-06-09 21:34:15 +08:00
|
|
|
struct file_system_type;
|
2018-11-04 19:48:34 +08:00
|
|
|
extern struct vfsmount *fc_mount(struct fs_context *fc);
|
|
|
|
|
extern struct vfsmount *vfs_create_mount(struct fs_context *fc);
|
2006-06-09 21:34:15 +08:00
|
|
|
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
|
|
|
|
|
int flags, const char *name,
|
|
|
|
|
void *data);
|
2017-02-01 01:06:16 +08:00
|
|
|
extern struct vfsmount *vfs_submount(const struct dentry *mountpoint,
|
|
|
|
|
struct file_system_type *type,
|
|
|
|
|
const char *name, void *data);
|
2006-06-09 21:34:15 +08:00
|
|
|
|
2011-01-15 03:10:03 +08:00
|
|
|
extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
|
2005-04-17 06:20:36 +08:00
|
|
|
extern void mark_mounts_for_expiry(struct list_head *mounts);
|
|
|
|
|
|
2015-02-11 07:20:49 +08:00
|
|
|
extern dev_t name_to_dev_t(const char *name);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2016-09-28 13:27:17 +08:00
|
|
|
extern unsigned int sysctl_mount_max;
|
|
|
|
|
|
2016-11-24 05:03:41 +08:00
|
|
|
extern bool path_is_mountpoint(const struct path *path);
|
|
|
|
|
|
2020-06-04 16:48:19 +08:00
|
|
|
extern void kern_unmount_array(struct vfsmount *mnt[], unsigned int num);
|
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
#endif /* _LINUX_MOUNT_H */
|