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Al Viro bcf0d9d4b7 ecryptfs: fix unlink and rmdir in face of underlying fs modifications
A problem similar to the one caught in commit 74dd7c97ea ("ecryptfs_rename():
verify that lower dentries are still OK after lock_rename()") exists for
unlink/rmdir as well.

Instead of playing with dget_parent() of underlying dentry of victim
and hoping it's the same as underlying dentry of our directory,
do the following:
        * find the underlying dentry of victim
        * find the underlying directory of victim's parent (stable
since the victim is ecryptfs dentry and inode of its parent is
held exclusive by the caller).
        * lock the inode of dentry underlying the victim's parent
        * check that underlying dentry of victim is still hashed and
has the right parent - it can be moved, but it can't be moved to/from
the directory we are holding exclusive.  So while ->d_parent itself
might not be stable, the result of comparison is.

If the check passes, everything is fine - underlying directory is locked,
underlying victim is still a child of that directory and we can go ahead
and feed them to vfs_unlink().  As in the current mainline we need to
pin the underlying dentry of victim, so that it wouldn't go negative under
us, but that's the only temporary reference that needs to be grabbed there.
Underlying dentry of parent won't go away (it's pinned by the parent,
which is held by caller), so there's no need to grab it.

The same problem (with the same solution) exists for rmdir.  Moreover,
rename gets simpler and more robust with the same "don't bother with
dget_parent()" approach.

Fixes: 74dd7c97ea "ecryptfs_rename(): verify that lower dentries are still OK after lock_rename()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-11-10 11:57:44 -05:00
Documentation hwmon fixes for v5.4-rc3 2019-10-13 08:40:31 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch USB fixes for 5.4-rc3 2019-10-12 15:37:12 -07:00
block blk-wbt: fix performance regression in wbt scale_up/scale_down 2019-10-06 09:26:41 -06:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
drivers hwmon fixes for v5.4-rc3 2019-10-13 08:40:31 -07:00
fs ecryptfs: fix unlink and rmdir in face of underlying fs modifications 2019-11-10 11:57:44 -05:00
include hwmon fixes for v5.4-rc3 2019-10-13 08:40:31 -07:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel audit_get_nd(): don't unlock parent too early 2019-11-10 11:56:55 -05:00
lib Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-10-12 14:46:14 -07:00
mm for-linus-20191010 2019-10-11 08:45:32 -07:00
net NFS Client Bugfixes for Linux 5.4-rc3 2019-10-11 14:28:59 -07:00
samples rpmsg updates for v5.4 2019-09-22 10:58:15 -07:00
scripts A few tracing fixes: 2019-10-13 14:47:10 -07:00
security selinux/stable-5.4 PR 20191007 2019-10-08 10:51:37 -07:00
sound sound fixes for 5.4-rc1 2019-09-24 16:46:16 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-10-12 15:15:17 -07:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM/arm fixes for 5.4, take #1 2019-10-03 12:08:50 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2019-09-18 12:34:53 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS USB fixes for 5.4-rc3 2019-10-12 15:37:12 -07:00
Makefile Linux 5.4-rc3 2019-10-13 16:37:36 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.