lxc: backport patch to fix CVE-2022-47952

Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

recipes-containers/lxc/files/0001-Patching-an-incoming-CVE-CVE-2022-47952.patch

@@ -0,0 +1,76 @@
+From 1b0469530d7a38b8f8990e114b52530d1bf7f3b8 Mon Sep 17 00:00:00 2001
+From: Maher Azzouzi <maherazz04@gmail.com>
+Date: Sun, 25 Dec 2022 13:50:25 +0100
+Subject: [PATCH] Patching an incoming CVE (CVE-2022-47952)
+
+lxc-user-nic in lxc through 5.0.1 is installed setuid root, and may
+allow local users to infer whether any file exists, even within a
+protected directory tree, because "Failed to open" often indicates
+that a file does not exist, whereas "does not refer to a network
+namespace path" often indicates that a file exists. NOTE: this is
+different from CVE-2018-6556 because the CVE-2018-6556 fix design was
+based on the premise that "we will report back to the user that the
+open() failed but the user has no way of knowing why it failed";
+however, in many realistic cases, there are no plausible reasons for
+failing except that the file does not exist.
+
+PoC:
+> % ls /l
+> ls: cannot open directory '/l': Permission denied
+> % /usr/lib/x86_64-linux-gnu/lxc/lxc-user-nic delete lol lol /l/h/tt h h
+> cmd/lxc_user_nic.c: 1096: main: Failed to open "/l/h/tt" <----- file does not exist.
+> % /usr/lib/x86_64-linux-gnu/lxc/lxc-user-nic delete lol lol /l/h/t h h
+> cmd/lxc_user_nic.c: 1101: main: Path "/l/h/t" does not refer to a network namespace path <---- file exist!
+
+Upstream-Status: Backport from https://github.com/lxc/lxc/commit/1b0469530d7a38b8f8990e114b52530d1bf7f3b8
+CVE: CVE-2022-47952
+
+Signed-off-by: MaherAzzouzi <maherazz04@gmail.com>
+Acked-by: Serge Hallyn <serge@hallyn.com>
+Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
+---
+ src/lxc/cmd/lxc_user_nic.c | 15 ++++++---------
+ 1 file changed, 6 insertions(+), 9 deletions(-)
+
+diff --git a/src/lxc/cmd/lxc_user_nic.c b/src/lxc/cmd/lxc_user_nic.c
+index a91e2259d..69bc6f17d 100644
+--- a/src/lxc/cmd/lxc_user_nic.c
++++ b/src/lxc/cmd/lxc_user_nic.c
+@@ -1085,20 +1085,17 @@ int main(int argc, char *argv[])
+ 	} else if (request == LXC_USERNIC_DELETE) {
+ 		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.
+-		 */
++		// Keep in mind CVE-2022-47952: It's crucial not to leak any
++		// information whether open() succeeded of failed.
++
+ 		netns_fd = open(args.pid, O_PATH | O_CLOEXEC);
+ 		if (netns_fd < 0) {
+-			usernic_error("Failed to open \"%s\"\n", args.pid);
++			usernic_error("Failed while opening netns file for \"%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);
++			usernic_error("Failed while opening netns file for \"%s\"\n", args.pid);
+ 			close(netns_fd);
+ 			_exit(EXIT_FAILURE);
+ 		}
+@@ -1112,7 +1109,7 @@ int main(int argc, char *argv[])
+ 		/* Now get an fd that we can use in setns() calls. */
+ 		ret = open(opath, O_RDONLY | O_CLOEXEC);
+ 		if (ret < 0) {
+-			CMD_SYSERROR("Failed to open \"%s\"\n", args.pid);
++			CMD_SYSERROR("Failed while opening netns file for \"%s\"\n", args.pid);
+ 			close(netns_fd);
+ 			_exit(EXIT_FAILURE);
+ 		}
+-- 
+2.34.1
+

recipes-containers/lxc/lxc_git.bb

@@ -48,6 +48,7 @@ SRC_URI = "git://github.com/lxc/lxc.git;branch=stable-4.0;protocol=https \
 	file://tests-our-init-is-not-busybox.patch \
 	file://dnsmasq.conf \
 	file://lxc-net \
+	file://0001-Patching-an-incoming-CVE-CVE-2022-47952.patch \
 	"
 
 SRCREV = "5ba5725cb4a210c25707beeca64fde5f561d1c71"