github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-08 22:52:35 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph
Linux kernel source tree
786,904 Commits 1 Branch 934 Tags 20 GiB
C 97%
Assembly 1%
Shell 0.6%
Rust 0.5%
Python 0.4%
Other 0.3%
1856bbbea6
Go to file
Daniel Borkmann 1856bbbea6 ipvlan: disallow userns cap_net_admin to change global mode/flags 
[ Upstream commit 7cc9f7003a ]

When running Docker with userns isolation e.g. --userns-remap="default"
and spawning up some containers with CAP_NET_ADMIN under this realm, I
noticed that link changes on ipvlan slave device inside that container
can affect all devices from this ipvlan group which are in other net
namespaces where the container should have no permission to make changes
to, such as the init netns, for example.

This effectively allows to undo ipvlan private mode and switch globally to
bridge mode where slaves can communicate directly without going through
hostns, or it allows to switch between global operation mode (l2/l3/l3s)
for everyone bound to the given ipvlan master device. libnetwork plugin
here is creating an ipvlan master and ipvlan slave in hostns and a slave
each that is moved into the container's netns upon creation event.

* In hostns:

  # ip -d a
  [...]
  8: cilium_host@bond0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
     link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
     ipvlan  mode l3 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
     inet 10.41.0.1/32 scope link cilium_host
       valid_lft forever preferred_lft forever
  [...]

* Spawn container & change ipvlan mode setting inside of it:

  # docker run -dt --cap-add=NET_ADMIN --network cilium-net --name client -l app=test cilium/netperf
  9fff485d69dcb5ce37c9e33ca20a11ccafc236d690105aadbfb77e4f4170879c

  # docker exec -ti client ip -d a
  [...]
  10: cilium0@if4: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
      ipvlan  mode l3 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
      inet 10.41.197.43/32 brd 10.41.197.43 scope global cilium0
         valid_lft forever preferred_lft forever

  # docker exec -ti client ip link change link cilium0 name cilium0 type ipvlan mode l2

  # docker exec -ti client ip -d a
  [...]
  10: cilium0@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
      ipvlan  mode l2 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
      inet 10.41.197.43/32 brd 10.41.197.43 scope global cilium0
         valid_lft forever preferred_lft forever

* In hostns (mode switched to l2):

  # ip -d a
  [...]
  8: cilium_host@bond0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
      ipvlan  mode l2 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
      inet 10.41.0.1/32 scope link cilium_host
         valid_lft forever preferred_lft forever
  [...]

Same l3 -> l2 switch would also happen by creating another slave inside
the container's network namespace when specifying the existing cilium0
link to derive the actual (bond0) master:

  # docker exec -ti client ip link add link cilium0 name cilium1 type ipvlan mode l2

  # docker exec -ti client ip -d a
  [...]
  2: cilium1@if4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
      link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
      ipvlan  mode l2 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
  10: cilium0@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
      ipvlan  mode l2 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
      inet 10.41.197.43/32 brd 10.41.197.43 scope global cilium0
         valid_lft forever preferred_lft forever

* In hostns:

  # ip -d a
  [...]
  8: cilium_host@bond0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
      link/ether 0c:c4:7a:e1:3d:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 65535
      ipvlan  mode l2 bridge numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
      inet 10.41.0.1/32 scope link cilium_host
         valid_lft forever preferred_lft forever
  [...]

One way to mitigate it is to check CAP_NET_ADMIN permissions of
the ipvlan master device's ns, and only then allow to change
mode or flags for all devices bound to it. Above two cases are
then disallowed after the patch.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-19 13:12:40 +01:00
arch perf/x86/intel: Implement support for TSX Force Abort 2019-03-13 14:02:41 -07:00
block blk-iolatency: fix IO hang due to negative inflight counter 2019-03-13 14:02:38 -07:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto net: crypto set sk to NULL when af_alg_release. 2019-02-23 09:07:24 +01:00
Documentation dt-bindings: eeprom: at24: add "atmel,24c2048" compatible string 2019-02-20 10:25:35 +01:00
drivers ipvlan: disallow userns cap_net_admin to change global mode/flags 2019-03-19 13:12:40 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs cifs: allow calling SMB2_xxx_free(NULL) 2019-03-13 14:02:40 -07:00
include drm: disable uncached DMA optimization for ARM and arm64 2019-03-13 14:02:40 -07:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-22 21:40:34 +01:00
ipc ipc/shm.c: use ERR_CAST() for shm_lock() error return 2018-10-05 16:32:04 -07:00
kernel bpf: Fix syscall's stackmap lookup potential deadlock 2019-03-13 14:02:36 -07:00
lib lib/test_kmod.c: potential double free in error handling 2019-03-13 14:02:32 -07:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm, memory_hotplug: fix off-by-one in is_pageblock_removable 2019-03-13 14:02:32 -07:00
net ipv6: route: purge exception on removal 2019-03-19 13:12:40 +01:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts scripts/gdb: fix lx-version string output 2019-02-12 19:47:20 +01:00
security apparmor: Fix aa_label_build() error handling for failed merges 2019-03-13 14:02:32 -07:00
sound ASoC: imx-audmux: change snprintf to scnprintf for possible overflow 2019-03-05 17:58:47 +01:00
tools perf trace: Support multiple "vfs_getname" probes 2019-03-13 14:02:37 -07:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt kvm: fix kvm_ioctl_create_device() reference counting (CVE-2019-6974) 2019-02-12 19:47:25 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:37:25 +01:00
Makefile Linux 4.19.29 2019-03-13 14:02:41 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.