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Filename Latest commit message Latest commit date
Aurelien Aptel e76e39f7c6 cifs: fix rename() by ensuring source handle opened with DELETE bit
commit 86f740f2aed5ea7fe1aa86dc2df0fb4ab0f71088 upstream.

To rename a file in SMB2 we open it with the DELETE access and do a
special SetInfo on it. If the handle is missing the DELETE bit the
server will fail the SetInfo with STATUS_ACCESS_DENIED.

We currently try to reuse any existing opened handle we have with
cifs_get_writable_path(). That function looks for handles with WRITE
access but doesn't check for DELETE, making rename() fail if it finds
a handle to reuse. Simple reproducer below.

To select handles with the DELETE bit, this patch adds a flag argument
to cifs_get_writable_path() and find_writable_file() and the existing
'bool fsuid_only' argument is converted to a flag.

The cifsFileInfo struct only stores the UNIX open mode but not the
original SMB access flags. Since the DELETE bit is not mapped in that
mode, this patch stores the access mask in cifs_fid on file open,
which is accessible from cifsFileInfo.

Simple reproducer:

	#include <stdio.h>
	#include <stdlib.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <fcntl.h>
	#include <unistd.h>
	#define E(s) perror(s), exit(1)

	int main(int argc, char *argv[])
	{
		int fd, ret;
		if (argc != 3) {
			fprintf(stderr, "Usage: %s A B\n"
			"create&open A in write mode, "
			"rename A to B, close A\n", argv[0]);
			return 0;
		}

		fd = openat(AT_FDCWD, argv[1], O_WRONLY|O_CREAT|O_SYNC, 0666);
		if (fd == -1) E("openat()");

		ret = rename(argv[1], argv[2]);
		if (ret) E("rename()");

		ret = close(fd);
		if (ret) E("close()");

		return ret;
	}

$ gcc -o bugrename bugrename.c
$ ./bugrename /mnt/a /mnt/b
rename(): Permission denied

Fixes: 8de9e86c67 ("cifs: create a helper to find a writeable handle by path name")
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-12 13:00:18 +01:00
arch arch/csky: fix some Kconfig typos 2020-03-12 13:00:17 +01:00
block block, bfq: do not insert oom queue into position tree 2020-03-12 13:00:08 +01:00
certs
crypto crypto: rename sm3-256 to sm3 in hash_algo_name 2020-02-28 17:22:26 +01:00
Documentation netfilter: nf_flowtable: fix documentation 2020-03-05 16:43:51 +01:00
drivers binder: prevent UAF for binderfs devices II 2020-03-12 13:00:17 +01:00
fs cifs: fix rename() by ensuring source handle opened with DELETE bit 2020-03-12 13:00:18 +01:00
include blktrace: Protect q->blk_trace with RCU 2020-03-05 16:43:52 +01:00
init kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 17:22:20 +01:00
kernel blktrace: fix dereference after null check 2020-03-12 13:00:10 +01:00
lib kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
LICENSES
mm mm, thp: fix defrag setting if newline is not used 2020-03-05 16:43:51 +01:00
net netfilter: nft_tunnel: no need to call htons() when dumping ports 2020-03-05 16:43:50 +01:00
samples
scripts kbuild: move headers_check rule to usr/include/Makefile 2020-03-05 16:43:47 +01:00
security efi: Only print errors about failing to get certs if EFI vars are found 2020-03-12 13:00:14 +01:00
sound ALSA: hda/realtek - Enable the headset of ASUS B9450FA with ALC294 2020-03-12 13:00:18 +01:00
tools selftests: forwarding: vxlan_bridge_1d: use more proper tos value 2020-03-12 13:00:17 +01:00
usr kbuild: fix 'No such file or directory' warning when cleaning 2020-03-12 13:00:09 +01:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.24 2020-03-05 16:43:52 +01:00
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.