[bug#34446] Runc container escape patches CVE-2019-5736

[bug#34446] Runc container escape patches CVE-2019-5736

[Leo Famulari]

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These patches aim to fix CVE-2019-5736 in runc / Docker:

https://seclists.org/oss-sec/2019/q1/119

However, after applying these patches, Docker fails to build as shown
below. Runc, docker-cli, and containerd still build.

Please help :)

------
phase `setup-environment' succeeded after 0.0 seconds
starting phase `build'
# WARNING! I don't seem to be running in a Docker container.
# The result of this command might be an incorrect build, and will not be
# officially supported.
#
# Try this instead: make all
#

Removing bundles/

---> Making bundle: dynbinary (in bundles/dynbinary)
Building: bundles/dynbinary-daemon/dockerd-dev
# github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables
.gopath/src/github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables/iptables.go:90:15: undefined: exec.Guix_doesnt_want_LookPath
.gopath/src/github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables/iptables.go:90:45: invalid character U+005C '\'
Backtrace:
           4 (primitive-load "/gnu/store/n5jmx2wksfvcrwlpv2zafd5hany…")
In ice-9/eval.scm:
   191:35  3 (_ _)
In srfi/srfi-1.scm:
   863:16  2 (every1 #<procedure ac28a0 at /gnu/store/rkv7z31csb2xa…> …)
In /gnu/store/rkv7z31csb2xandzhnvm5kc0i78pf0ay-module-import/guix/build/gnu-build-system.scm:
   799:28  1 (_ _)
In /gnu/store/rkv7z31csb2xandzhnvm5kc0i78pf0ay-module-import/guix/build/utils.scm:
    616:6  0 (invoke _ . _)

/gnu/store/rkv7z31csb2xandzhnvm5kc0i78pf0ay-module-import/guix/build/utils.scm:616:6: In procedure invoke:
Throw to key `srfi-34' with args `(#<condition &invoke-error [program: "hack/make.sh" arguments: ("dynbinary") exit-status: 2 term-signal: #f stop-signal: #f] 491cc0>)'.
builder for `/gnu/store/ihdm0nlw118mrb8wq127864g9pgrmghk-docker-18.09.2.drv' failed with exit code 1
build of /gnu/store/ihdm0nlw118mrb8wq127864g9pgrmghk-docker-18.09.2.drv failed
View build log at '/var/log/guix/drvs/ih/dm0nlw118mrb8wq127864g9pgrmghk-docker-18.09.2.drv.bz2'.
guix build: error: build of `/gnu/store/ihdm0nlw118mrb8wq127864g9pgrmghk-docker-18.09.2.drv' failed
------

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[bug#34446] Runc container escape patches CVE-2019-5736

[Danny Milosavljevic]

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Hi Leo,

as originally released by upstream, Docker looks up auxiliary commands in PATH,
using a Go function called "LookPath".

Our package definition patches a lot of the specific LookPath calls to
refer to inputs by absolute path.

I've booby-trapped the remaining LookPath calls so we won't accidentially
have an internal tool looked up in $PATH.

If we have not forgotten any LookPath calls, there should have been no remaining
LookPath calls and it would not have failed the build.

> .gopath/src/github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables/iptables.go:90:15: undefined: exec.Guix_doesnt_want_LookPath
> .gopath/src/github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables/iptables.go:90:45: invalid character U+005C '\'

Please examine line 90.  It probably has a LookPath line with a new argument we
haven't seen before.

That means we'd have to find out which Guix package has an executable named like
the argument and add a case to the existing LookPath substituter in order to
also substitute it.

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[bug#34446] Runc container escape patches CVE-2019-5736

[Danny Milosavljevic]

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> That means we'd have to find out which Guix package has an executable named like
> the argument and add a case to the existing LookPath substituter in order to
> also substitute it.

and add an input to the "docker" package if necessary.

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bug#34446: Runc container escape patches CVE-2019-5736

[Leo Famulari]

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On Tue, Feb 12, 2019 at 01:10:34AM +0100, Danny Milosavljevic wrote:
> as originally released by upstream, Docker looks up auxiliary commands in PATH,
> using a Go function called "LookPath".
> 
> Our package definition patches a lot of the specific LookPath calls to
> refer to inputs by absolute path.
> 
> I've booby-trapped the remaining LookPath calls so we won't accidentially
> have an internal tool looked up in $PATH.
> 
> If we have not forgotten any LookPath calls, there should have been no remaining
> LookPath calls and it would not have failed the build.

Thanks for explaining this :)

> > .gopath/src/github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables/iptables.go:90:15: undefined: exec.Guix_doesnt_want_LookPath
> > .gopath/src/github.com/docker/docker/vendor/github.com/docker/libnetwork/iptables/iptables.go:90:45: invalid character U+005C '\'
> 
> Please examine line 90.  It probably has a LookPath line with a new argument we
> haven't seen before.

Okay, they added a lookup for 'iptables-legacy' which is what Debian has
renamed iptables. I changed this to just look up 'iptables' since its
equivalent on our end and in how the Docker code uses it and pushed as
ea7cddaac782b2cdc789a354e172356ed5c183e7.

Thanks again for your help!

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[bug#34446] [PATCH 1/2] gnu: runc: Update to 1.0.0-rc6 [fixes CVE-2019-5736].

[Leo Famulari]

* gnu/packages/virtualization.scm (runc): Update to 1.0.0-rc6.
[source]: Use a descriptive file-name. Add 'runc-CVE-2019-5736.patch'
* gnu/packages/patches/runc-CVE-2019-5736.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
---
 gnu/local.mk                                  |   1 +
 gnu/packages/patches/runc-CVE-2019-5736.patch | 343 ++++++++++++++++++
 gnu/packages/virtualization.scm               |   6 +-
 3 files changed, 348 insertions(+), 2 deletions(-)
 create mode 100644 gnu/packages/patches/runc-CVE-2019-5736.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 3bb60d3ade..5fbd02e120 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1205,6 +1205,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/ruby-concurrent-test-arm.patch		\
   %D%/packages/patches/ruby-rack-ignore-failing-test.patch      \
   %D%/packages/patches/ruby-tzinfo-data-ignore-broken-test.patch\
+  %D%/packages/patches/runc-CVE-2019-5736.patch			\
   %D%/packages/patches/rust-1.19-mrustc.patch			\
   %D%/packages/patches/rust-1.25-accept-more-detailed-gdb-lines.patch \
   %D%/packages/patches/rust-bootstrap-stage0-test.patch		\
diff --git a/gnu/packages/patches/runc-CVE-2019-5736.patch b/gnu/packages/patches/runc-CVE-2019-5736.patch
new file mode 100644
index 0000000000..f629fcbfb4
--- /dev/null
+++ b/gnu/packages/patches/runc-CVE-2019-5736.patch
@@ -0,0 +1,343 @@
+Fix CVE-2019-5736:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5736
+https://seclists.org/oss-sec/2019/q1/119
+
+Patch copied from upstream source repository:
+
+https://github.com/opencontainers/runc/commit/0a8e4117e7f715d5fbeef398405813ce8e88558b
+
+From 0a8e4117e7f715d5fbeef398405813ce8e88558b Mon Sep 17 00:00:00 2001
+From: Aleksa Sarai <asarai@suse.de>
+Date: Wed, 9 Jan 2019 13:40:01 +1100
+Subject: [PATCH] nsenter: clone /proc/self/exe to avoid exposing host binary
+ to container
+
+There are quite a few circumstances where /proc/self/exe pointing to a
+pretty important container binary is a _bad_ thing, so to avoid this we
+have to make a copy (preferably doing self-clean-up and not being
+writeable).
+
+We require memfd_create(2) -- though there is an O_TMPFILE fallback --
+but we can always extend this to use a scratch MNT_DETACH overlayfs or
+tmpfs. The main downside to this approach is no page-cache sharing for
+the runc binary (which overlayfs would give us) but this is far less
+complicated.
+
+This is only done during nsenter so that it happens transparently to the
+Go code, and any libcontainer users benefit from it. This also makes
+ExtraFiles and --preserve-fds handling trivial (because we don't need to
+worry about it).
+
+Fixes: CVE-2019-5736
+Co-developed-by: Christian Brauner <christian.brauner@ubuntu.com>
+Signed-off-by: Aleksa Sarai <asarai@suse.de>
+---
+ libcontainer/nsenter/cloned_binary.c | 268 +++++++++++++++++++++++++++
+ libcontainer/nsenter/nsexec.c        |  11 ++
+ 2 files changed, 279 insertions(+)
+ create mode 100644 libcontainer/nsenter/cloned_binary.c
+
+diff --git a/libcontainer/nsenter/cloned_binary.c b/libcontainer/nsenter/cloned_binary.c
+new file mode 100644
+index 000000000..c8a42c23f
+--- /dev/null
++++ b/libcontainer/nsenter/cloned_binary.c
+@@ -0,0 +1,268 @@
++/*
++ * Copyright (C) 2019 Aleksa Sarai <cyphar@cyphar.com>
++ * Copyright (C) 2019 SUSE LLC
++ *
++ * Licensed under the Apache License, Version 2.0 (the "License");
++ * you may not use this file except in compliance with the License.
++ * You may obtain a copy of the License at
++ *
++ *     http://www.apache.org/licenses/LICENSE-2.0
++ *
++ * Unless required by applicable law or agreed to in writing, software
++ * distributed under the License is distributed on an "AS IS" BASIS,
++ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
++ * See the License for the specific language governing permissions and
++ * limitations under the License.
++ */
++
++#define _GNU_SOURCE
++#include <unistd.h>
++#include <stdio.h>
++#include <stdlib.h>
++#include <stdbool.h>
++#include <string.h>
++#include <limits.h>
++#include <fcntl.h>
++#include <errno.h>
++
++#include <sys/types.h>
++#include <sys/stat.h>
++#include <sys/vfs.h>
++#include <sys/mman.h>
++#include <sys/sendfile.h>
++#include <sys/syscall.h>
++
++/* Use our own wrapper for memfd_create. */
++#if !defined(SYS_memfd_create) && defined(__NR_memfd_create)
++#  define SYS_memfd_create __NR_memfd_create
++#endif
++#ifdef SYS_memfd_create
++#  define HAVE_MEMFD_CREATE
++/* memfd_create(2) flags -- copied from <linux/memfd.h>. */
++#  ifndef MFD_CLOEXEC
++#    define MFD_CLOEXEC       0x0001U
++#    define MFD_ALLOW_SEALING 0x0002U
++#  endif
++int memfd_create(const char *name, unsigned int flags)
++{
++	return syscall(SYS_memfd_create, name, flags);
++}
++#endif
++
++/* This comes directly from <linux/fcntl.h>. */
++#ifndef F_LINUX_SPECIFIC_BASE
++#  define F_LINUX_SPECIFIC_BASE 1024
++#endif
++#ifndef F_ADD_SEALS
++#  define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
++#  define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
++#endif
++#ifndef F_SEAL_SEAL
++#  define F_SEAL_SEAL   0x0001	/* prevent further seals from being set */
++#  define F_SEAL_SHRINK 0x0002	/* prevent file from shrinking */
++#  define F_SEAL_GROW   0x0004	/* prevent file from growing */
++#  define F_SEAL_WRITE  0x0008	/* prevent writes */
++#endif
++
++#define RUNC_SENDFILE_MAX 0x7FFFF000 /* sendfile(2) is limited to 2GB. */
++#ifdef HAVE_MEMFD_CREATE
++#  define RUNC_MEMFD_COMMENT "runc_cloned:/proc/self/exe"
++#  define RUNC_MEMFD_SEALS \
++	(F_SEAL_SEAL | F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE)
++#endif
++
++static void *must_realloc(void *ptr, size_t size)
++{
++	void *old = ptr;
++	do {
++		ptr = realloc(old, size);
++	} while(!ptr);
++	return ptr;
++}
++
++/*
++ * Verify whether we are currently in a self-cloned program (namely, is
++ * /proc/self/exe a memfd). F_GET_SEALS will only succeed for memfds (or rather
++ * for shmem files), and we want to be sure it's actually sealed.
++ */
++static int is_self_cloned(void)
++{
++	int fd, ret, is_cloned = 0;
++
++	fd = open("/proc/self/exe", O_RDONLY|O_CLOEXEC);
++	if (fd < 0)
++		return -ENOTRECOVERABLE;
++
++#ifdef HAVE_MEMFD_CREATE
++	ret = fcntl(fd, F_GET_SEALS);
++	is_cloned = (ret == RUNC_MEMFD_SEALS);
++#else
++	struct stat statbuf = {0};
++	ret = fstat(fd, &statbuf);
++	if (ret >= 0)
++		is_cloned = (statbuf.st_nlink == 0);
++#endif
++	close(fd);
++	return is_cloned;
++}
++
++/*
++ * Basic wrapper around mmap(2) that gives you the file length so you can
++ * safely treat it as an ordinary buffer. Only gives you read access.
++ */
++static char *read_file(char *path, size_t *length)
++{
++	int fd;
++	char buf[4096], *copy = NULL;
++
++	if (!length)
++		return NULL;
++
++	fd = open(path, O_RDONLY | O_CLOEXEC);
++	if (fd < 0)
++		return NULL;
++
++	*length = 0;
++	for (;;) {
++		int n;
++
++		n = read(fd, buf, sizeof(buf));
++		if (n < 0)
++			goto error;
++		if (!n)
++			break;
++
++		copy = must_realloc(copy, (*length + n) * sizeof(*copy));
++		memcpy(copy + *length, buf, n);
++		*length += n;
++	}
++	close(fd);
++	return copy;
++
++error:
++	close(fd);
++	free(copy);
++	return NULL;
++}
++
++/*
++ * A poor-man's version of "xargs -0". Basically parses a given block of
++ * NUL-delimited data, within the given length and adds a pointer to each entry
++ * to the array of pointers.
++ */
++static int parse_xargs(char *data, int data_length, char ***output)
++{
++	int num = 0;
++	char *cur = data;
++
++	if (!data || *output != NULL)
++		return -1;
++
++	while (cur < data + data_length) {
++		num++;
++		*output = must_realloc(*output, (num + 1) * sizeof(**output));
++		(*output)[num - 1] = cur;
++		cur += strlen(cur) + 1;
++	}
++	(*output)[num] = NULL;
++	return num;
++}
++
++/*
++ * "Parse" out argv and envp from /proc/self/cmdline and /proc/self/environ.
++ * This is necessary because we are running in a context where we don't have a
++ * main() that we can just get the arguments from.
++ */
++static int fetchve(char ***argv, char ***envp)
++{
++	char *cmdline = NULL, *environ = NULL;
++	size_t cmdline_size, environ_size;
++
++	cmdline = read_file("/proc/self/cmdline", &cmdline_size);
++	if (!cmdline)
++		goto error;
++	environ = read_file("/proc/self/environ", &environ_size);
++	if (!environ)
++		goto error;
++
++	if (parse_xargs(cmdline, cmdline_size, argv) <= 0)
++		goto error;
++	if (parse_xargs(environ, environ_size, envp) <= 0)
++		goto error;
++
++	return 0;
++
++error:
++	free(environ);
++	free(cmdline);
++	return -EINVAL;
++}
++
++static int clone_binary(void)
++{
++	int binfd, memfd;
++	ssize_t sent = 0;
++
++#ifdef HAVE_MEMFD_CREATE
++	memfd = memfd_create(RUNC_MEMFD_COMMENT, MFD_CLOEXEC | MFD_ALLOW_SEALING);
++#else
++	memfd = open("/tmp", O_TMPFILE | O_EXCL | O_RDWR | O_CLOEXEC, 0711);
++#endif
++	if (memfd < 0)
++		return -ENOTRECOVERABLE;
++
++	binfd = open("/proc/self/exe", O_RDONLY | O_CLOEXEC);
++	if (binfd < 0)
++		goto error;
++
++	sent = sendfile(memfd, binfd, NULL, RUNC_SENDFILE_MAX);
++	close(binfd);
++	if (sent < 0)
++		goto error;
++
++#ifdef HAVE_MEMFD_CREATE
++	int err = fcntl(memfd, F_ADD_SEALS, RUNC_MEMFD_SEALS);
++	if (err < 0)
++		goto error;
++#else
++	/* Need to re-open "memfd" as read-only to avoid execve(2) giving -EXTBUSY. */
++	int newfd;
++	char *fdpath = NULL;
++
++	if (asprintf(&fdpath, "/proc/self/fd/%d", memfd) < 0)
++		goto error;
++	newfd = open(fdpath, O_RDONLY | O_CLOEXEC);
++	free(fdpath);
++	if (newfd < 0)
++		goto error;
++
++	close(memfd);
++	memfd = newfd;
++#endif
++	return memfd;
++
++error:
++	close(memfd);
++	return -EIO;
++}
++
++int ensure_cloned_binary(void)
++{
++	int execfd;
++	char **argv = NULL, **envp = NULL;
++
++	/* Check that we're not self-cloned, and if we are then bail. */
++	int cloned = is_self_cloned();
++	if (cloned > 0 || cloned == -ENOTRECOVERABLE)
++		return cloned;
++
++	if (fetchve(&argv, &envp) < 0)
++		return -EINVAL;
++
++	execfd = clone_binary();
++	if (execfd < 0)
++		return -EIO;
++
++	fexecve(execfd, argv, envp);
++	return -ENOEXEC;
++}
+diff --git a/libcontainer/nsenter/nsexec.c b/libcontainer/nsenter/nsexec.c
+index 28269dfc0..7750af35e 100644
+--- a/libcontainer/nsenter/nsexec.c
++++ b/libcontainer/nsenter/nsexec.c
+@@ -534,6 +534,9 @@ void join_namespaces(char *nslist)
+ 	free(namespaces);
+ }
+ 
++/* Defined in cloned_binary.c. */
++extern int ensure_cloned_binary(void);
++
+ void nsexec(void)
+ {
+ 	int pipenum;
+@@ -549,6 +552,14 @@ void nsexec(void)
+ 	if (pipenum == -1)
+ 		return;
+ 
++	/*
++	 * We need to re-exec if we are not in a cloned binary. This is necessary
++	 * to ensure that containers won't be able to access the host binary
++	 * through /proc/self/exe. See CVE-2019-5736.
++	 */
++	if (ensure_cloned_binary() < 0)
++		bail("could not ensure we are a cloned binary");
++
+ 	/* Parse all of the netlink configuration. */
+ 	nl_parse(pipenum, &config);
+ 
diff --git a/gnu/packages/virtualization.scm b/gnu/packages/virtualization.scm
index f5e4540329..8a5af2e8ea 100644
--- a/gnu/packages/virtualization.scm
+++ b/gnu/packages/virtualization.scm
@@ -847,15 +847,17 @@ monitor/GPU.")
 (define-public runc
   (package
     (name "runc")
-    (version "1.0.0-rc5")
+    (version "1.0.0-rc6")
     (source (origin
               (method url-fetch)
               (uri (string-append
                     "https://github.com/opencontainers/runc/releases/"
                     "download/v" version "/runc.tar.xz"))
+              (file-name (string-append name "-" version ".tar.xz"))
+              (patches (search-patches "runc-CVE-2019-5736.patch"))
               (sha256
                (base32
-                "081avdzwnqpk368wbaihlzsypaxpj42d7699h7jgp0fks14x4103"))))
+                "1c7832dq70slkjh8qp2civ1wxhhdd2hrx84pq7db1mmqc9fdr3cc"))))
     (build-system go-build-system)
     (arguments
      '(#:import-path "github.com/opencontainers/runc"
-- 
2.20.1

[bug#34446] [PATCH 2/2] gnu: Docker: Update to 18.09.2.

[Leo Famulari]

* gnu/packages/docker.scm (%docker-version): Update to 18.09.2.
(docker, docker-cli): Adjust accordingly.
---
 gnu/packages/docker.scm | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/gnu/packages/docker.scm b/gnu/packages/docker.scm
index 992eb0dcc1..5a400e6490 100644
--- a/gnu/packages/docker.scm
+++ b/gnu/packages/docker.scm
@@ -43,7 +43,7 @@
   #:use-module (gnu packages version-control)
   #:use-module (gnu packages virtualization))
 
-(define %docker-version "18.09.0")
+(define %docker-version "18.09.2")
 
 (define-public python-docker-py
   (package
@@ -241,7 +241,7 @@ network attachments.")
       (file-name (git-file-name name version))
       (sha256
        (base32
-        "1liqbx58grqih6m8hz9y20y5waflv19pv15l3wl64skap2bsn21c"))
+        "1zfpk2n8j6gnwbrxrh6d6pj24y60dhbanpf55shrm2yxz54ka36c"))
       (patches
        (search-patches "docker-engine-test-noinstall.patch"
                        "docker-fix-tests.patch"))))
@@ -483,7 +483,7 @@ provisioning etc.")
       (file-name (git-file-name name version))
       (sha256
        (base32
-        "1ivisys20kphvbqlazc3bsg7pk0ykj9gjx5d4yg439x4n13jxwvb"))))
+        "0jzcqh1kqbfyj6ax7z67gihaqgjiz6ddz6rq6k458l68v7zn77r8"))))
     (build-system go-build-system)
     (arguments
      `(#:import-path "github.com/docker/cli"
-- 
2.20.1

[bug#34446] [PATCH 1/2] gnu: runc: Update to 1.0.0-rc6 [fixes CVE-2019-5736].

[Danny Milosavljevic]

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On Mon, 11 Feb 2019 19:27:35 -0500
Leo Famulari <leo@famulari.name> wrote:

>  (define-public runc
>    (package
>      (name "runc")
> -    (version "1.0.0-rc5")
> +    (version "1.0.0-rc6")
>      (source (origin
>                (method url-fetch)
>                (uri (string-append
>                      "https://github.com/opencontainers/runc/releases/"
>                      "download/v" version "/runc.tar.xz"))
> +              (file-name (string-append name "-" version ".tar.xz"))
> +              (patches (search-patches "runc-CVE-2019-5736.patch"))
>                (sha256
>                 (base32
> -                "081avdzwnqpk368wbaihlzsypaxpj42d7699h7jgp0fks14x4103"))))
> +                "1c7832dq70slkjh8qp2civ1wxhhdd2hrx84pq7db1mmqc9fdr3cc"))))
>      (build-system go-build-system)
>      (arguments
>       '(#:import-path "github.com/opencontainers/runc"

Docker still contains some vendored dependencies, among those github.com/opencontainers/runc,
in directory "vendor", and so does containerd.  It might make sense to also remove them now.

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bug#34459: Docker and containerd bundled dependencies — what to do?

[Leo Famulari]

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On Tue, Feb 12, 2019 at 01:45:01AM +0100, Danny Milosavljevic wrote:
> Docker still contains some vendored dependencies, among those github.com/opencontainers/runc,
> in directory "vendor", and so does containerd.  It might make sense to also remove them now.

I didn't do anything regarding the vendored / bundled deps in my patches
related to CVE-2019-5736 <https://bugs.gnu.org/34446>.

Regarding Docker, the update to 18.09.2 ostensibly fixed CVE-2019-5736,
I suppose by updating the bundled copy of runc.

For containerd I didn't change the package at all.

Both Docker and containerd depend on our runc package. If they don't
actually use it but instead use their bundled copy, we should remove the
dependency and document the bundling, or work on unbundling.

Unfortunately this is complicated for us in recent versions of Go:

https://lists.gnu.org/archive/html/guix-devel/2018-11/msg00223.html

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