diff options
Diffstat (limited to 'gnu/packages/patches/runc-CVE-2019-5736.patch')
| -rw-r--r-- | gnu/packages/patches/runc-CVE-2019-5736.patch | 343 |
1 files changed, 0 insertions, 343 deletions
diff --git a/gnu/packages/patches/runc-CVE-2019-5736.patch b/gnu/packages/patches/runc-CVE-2019-5736.patch deleted file mode 100644 index f629fcbfb4..0000000000 --- a/gnu/packages/patches/runc-CVE-2019-5736.patch +++ /dev/null @@ -1,343 +0,0 @@ -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); - |