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cherry-pick CVE-2018-6556 fix
from upstream's stable-3.0 branch
This commit is contained in:
parent
2d8021b3bf
commit
3aee60181b
115
debian/patches/extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch
vendored
Normal file
115
debian/patches/extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch
vendored
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@ -0,0 +1,115 @@
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From 590b215c4f5225cfb7fb58d9c56fabd5197bfdac Mon Sep 17 00:00:00 2001
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From: Christian Brauner <christian.brauner@ubuntu.com>
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Date: Wed, 25 Jul 2018 19:56:54 +0200
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Subject: [PATCH] CVE 2018-6556: verify netns fd in lxc-user-nic
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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(cherry picked from commit c1cf54ebf251fdbad1e971679614e81649f1c032)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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src/lxc/utils.h | 5 +++++
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src/lxc/cmd/lxc_user_nic.c | 35 ++++++++++++++++++++++++++++++++---
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src/lxc/utils.c | 12 ++++++++++++
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3 files changed, 49 insertions(+), 3 deletions(-)
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diff --git a/src/lxc/utils.h b/src/lxc/utils.h
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index ed486853..4dff26ae 100644
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--- a/src/lxc/utils.h
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+++ b/src/lxc/utils.h
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@@ -95,6 +95,10 @@
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#define CGROUP2_SUPER_MAGIC 0x63677270
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#endif
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+#ifndef NSFS_MAGIC
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+#define NSFS_MAGIC 0x6e736673
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+#endif
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+
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/* Useful macros */
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/* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
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#define LXC_NUMSTRLEN64 21
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@@ -580,6 +584,7 @@ extern void *must_realloc(void *orig, size_t sz);
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/* __typeof__ should be safe to use with all compilers. */
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typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
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extern bool has_fs_type(const char *path, fs_type_magic magic_val);
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+extern bool fhas_fs_type(int fd, fs_type_magic magic_val);
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extern bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val);
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extern bool lxc_nic_exists(char *nic);
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extern int lxc_make_tmpfile(char *template, bool rm);
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diff --git a/src/lxc/cmd/lxc_user_nic.c b/src/lxc/cmd/lxc_user_nic.c
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index ec9cd97e..c5beb6c8 100644
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--- a/src/lxc/cmd/lxc_user_nic.c
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+++ b/src/lxc/cmd/lxc_user_nic.c
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@@ -1179,12 +1179,41 @@ int main(int argc, char *argv[])
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exit(EXIT_FAILURE);
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}
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} else if (request == LXC_USERNIC_DELETE) {
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- netns_fd = open(args.pid, O_RDONLY);
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+ char opath[LXC_PROC_PID_FD_LEN];
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+
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+ /* Open the path with O_PATH which will not trigger an actual
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+ * open(). Don't report an errno to the caller to not leak
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+ * information whether the path exists or not.
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+ * When stracing setuid is stripped so this is not a concern
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+ * either.
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+ */
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+ netns_fd = open(args.pid, O_PATH | O_CLOEXEC);
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if (netns_fd < 0) {
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- usernic_error("Could not open \"%s\": %s\n", args.pid,
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- strerror(errno));
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+ usernic_error("Failed to open \"%s\"\n", args.pid);
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+ exit(EXIT_FAILURE);
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+ }
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+
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+ if (!fhas_fs_type(netns_fd, NSFS_MAGIC)) {
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+ usernic_error("Path \"%s\" does not refer to a network namespace path\n", args.pid);
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+ close(netns_fd);
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+ exit(EXIT_FAILURE);
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+ }
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+
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+ ret = snprintf(opath, sizeof(opath), "/proc/self/fd/%d", netns_fd);
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+ if (ret < 0 || (size_t)ret >= sizeof(opath)) {
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+ close(netns_fd);
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+ exit(EXIT_FAILURE);
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+ }
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+
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+ /* Now get an fd that we can use in setns() calls. */
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+ ret = open(opath, O_RDONLY | O_CLOEXEC);
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+ if (ret < 0) {
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+ usernic_error("Failed to open \"%s\": %s\n", args.pid, strerror(errno));
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+ close(netns_fd);
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exit(EXIT_FAILURE);
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}
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+ close(netns_fd);
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+ netns_fd = ret;
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}
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if (!create_db_dir(LXC_USERNIC_DB)) {
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diff --git a/src/lxc/utils.c b/src/lxc/utils.c
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index 9771b900..e6f600f9 100644
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--- a/src/lxc/utils.c
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+++ b/src/lxc/utils.c
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@@ -2551,6 +2551,18 @@ bool has_fs_type(const char *path, fs_type_magic magic_val)
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return has_type;
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}
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+bool fhas_fs_type(int fd, fs_type_magic magic_val)
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+{
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+ int ret;
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+ struct statfs sb;
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+
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+ ret = fstatfs(fd, &sb);
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+ if (ret < 0)
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+ return false;
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+
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+ return is_fs_type(&sb, magic_val);
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+}
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+
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bool lxc_nic_exists(char *nic)
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{
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#define __LXC_SYS_CLASS_NET_LEN 15 + IFNAMSIZ + 1
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--
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2.18.0
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1
debian/patches/series
vendored
1
debian/patches/series
vendored
@ -18,3 +18,4 @@ extra/0009-apparmor-update-current-profiles.patch
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extra/0010-apparmor-profile-generation.patch
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extra/0011-apparmor-allow-start-container-to-change-to-lxc.patch
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extra/0012-tests-add-test-for-generated-apparmor-profiles.patch
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extra/0013-CVE-2018-6556-verify-netns-fd-in-lxc-user-nic.patch
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