118 lines
3.9 KiB
Diff
118 lines
3.9 KiB
Diff
From d183654ec1a2cd1149bdb92601ccb7246bddb14e Mon Sep 17 00:00:00 2001
|
|
From: Christian Brauner <christian.brauner@ubuntu.com>
|
|
Date: Wed, 25 Jul 2018 19:56:54 +0200
|
|
Subject: [PATCH] CVE 2018-6556: verify netns fd in lxc-user-nic
|
|
|
|
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
|
|
---
|
|
src/lxc/lxc_user_nic.c | 35 ++++++++++++++++++++++++++++++++---
|
|
src/lxc/utils.c | 12 ++++++++++++
|
|
src/lxc/utils.h | 5 +++++
|
|
3 files changed, 49 insertions(+), 3 deletions(-)
|
|
|
|
ADDENDUM from vdupras@gentoo.org: Original patch from Christian didn't
|
|
include LXC_PROC_PID_FD_LEN define, but referenced it. This resulted in
|
|
code that doesn't compile. I fetched the definition from the stable-3.0
|
|
branch and included it to this patch. Also, this diff is regenerated
|
|
from lxc-2.1.1 tag instead of stable-2.0 branch.
|
|
|
|
diff --git a/src/lxc/lxc_user_nic.c b/src/lxc/lxc_user_nic.c
|
|
index 6f550f0d..09a342ac 100644
|
|
--- a/src/lxc/lxc_user_nic.c
|
|
+++ b/src/lxc/lxc_user_nic.c
|
|
@@ -1124,12 +1124,41 @@ int main(int argc, char *argv[])
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
} else if (request == LXC_USERNIC_DELETE) {
|
|
- netns_fd = open(args.pid, O_RDONLY);
|
|
+ char opath[LXC_PROC_PID_FD_LEN];
|
|
+
|
|
+ /* Open the path with O_PATH which will not trigger an actual
|
|
+ * open(). Don't report an errno to the caller to not leak
|
|
+ * information whether the path exists or not.
|
|
+ * When stracing setuid is stripped so this is not a concern
|
|
+ * either.
|
|
+ */
|
|
+ netns_fd = open(args.pid, O_PATH | O_CLOEXEC);
|
|
if (netns_fd < 0) {
|
|
- usernic_error("Could not open \"%s\": %s\n", args.pid,
|
|
- strerror(errno));
|
|
+ usernic_error("Failed to open \"%s\"\n", args.pid);
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
+
|
|
+ if (!fhas_fs_type(netns_fd, NSFS_MAGIC)) {
|
|
+ usernic_error("Path \"%s\" does not refer to a network namespace path\n", args.pid);
|
|
+ close(netns_fd);
|
|
+ exit(EXIT_FAILURE);
|
|
+ }
|
|
+
|
|
+ ret = snprintf(opath, sizeof(opath), "/proc/self/fd/%d", netns_fd);
|
|
+ if (ret < 0 || (size_t)ret >= sizeof(opath)) {
|
|
+ close(netns_fd);
|
|
+ exit(EXIT_FAILURE);
|
|
+ }
|
|
+
|
|
+ /* Now get an fd that we can use in setns() calls. */
|
|
+ ret = open(opath, O_RDONLY | O_CLOEXEC);
|
|
+ if (ret < 0) {
|
|
+ usernic_error("Failed to open \"%s\": %s\n", args.pid, strerror(errno));
|
|
+ close(netns_fd);
|
|
+ exit(EXIT_FAILURE);
|
|
+ }
|
|
+ close(netns_fd);
|
|
+ netns_fd = ret;
|
|
}
|
|
|
|
if (!create_db_dir(LXC_USERNIC_DB)) {
|
|
diff --git a/src/lxc/utils.c b/src/lxc/utils.c
|
|
index e6a44a51..c2a08a9d 100644
|
|
--- a/src/lxc/utils.c
|
|
+++ b/src/lxc/utils.c
|
|
@@ -2380,6 +2380,18 @@ bool has_fs_type(const char *path, fs_type_magic magic_val)
|
|
return has_type;
|
|
}
|
|
|
|
+bool fhas_fs_type(int fd, fs_type_magic magic_val)
|
|
+{
|
|
+ int ret;
|
|
+ struct statfs sb;
|
|
+
|
|
+ ret = fstatfs(fd, &sb);
|
|
+ if (ret < 0)
|
|
+ return false;
|
|
+
|
|
+ return is_fs_type(&sb, magic_val);
|
|
+}
|
|
+
|
|
bool lxc_nic_exists(char *nic)
|
|
{
|
|
#define __LXC_SYS_CLASS_NET_LEN 15 + IFNAMSIZ + 1
|
|
diff --git a/src/lxc/utils.h b/src/lxc/utils.h
|
|
index e83ed49e..06ec74d7 100644
|
|
--- a/src/lxc/utils.h
|
|
+++ b/src/lxc/utils.h
|
|
@@ -46,11 +46,16 @@
|
|
#define __S_ISTYPE(mode, mask) (((mode)&S_IFMT) == (mask))
|
|
#endif
|
|
|
|
+#ifndef NSFS_MAGIC
|
|
+#define NSFS_MAGIC 0x6e736673
|
|
+#endif
|
|
+
|
|
/* Useful macros */
|
|
/* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
|
|
#define LXC_NUMSTRLEN64 21
|
|
#define LXC_LINELEN 4096
|
|
#define LXC_IDMAPLEN 4096
|
|
+#define LXC_PROC_PID_FD_LEN (6 + LXC_NUMSTRLEN64 + 4 + LXC_NUMSTRLEN64 + 1)
|
|
|
|
/* returns 1 on success, 0 if there were any failures */
|
|
extern int lxc_rmdir_onedev(char *path, const char *exclude);
|
|
@@ -402,6 +407,7 @@ extern void *must_realloc(void *orig, size_t sz);
|
|
/* __typeof__ should be safe to use with all compilers. */
|
|
typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
|
|
extern bool has_fs_type(const char *path, fs_type_magic magic_val);
|
|
+extern bool fhas_fs_type(int fd, fs_type_magic magic_val);
|
|
extern bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val);
|
|
extern bool lxc_nic_exists(char *nic);
|