117 lines
3.6 KiB
Diff
117 lines
3.6 KiB
Diff
Fix CVE-2018-6556:
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https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-6556
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https://bugzilla.suse.com/show_bug.cgi?id=988348#c8
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Patch copied from upstream source repository:
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https://github.com/lxc/lxc/commit/c1cf54ebf251fdbad1e971679614e81649f1c032
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From c1cf54ebf251fdbad1e971679614e81649f1c032 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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Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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---
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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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src/lxc/utils.h | 5 +++++
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3 files changed, 49 insertions(+), 3 deletions(-)
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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 ec9cd97e0..c5beb6c8d 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 530b1f81a..3b854e35b 100644
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--- a/src/lxc/utils.c
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+++ b/src/lxc/utils.c
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@@ -2544,6 +2544,18 @@ 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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diff --git a/src/lxc/utils.h b/src/lxc/utils.h
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index 6a0bebded..0805f5d0d 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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