From: Omkar Patil <[email protected]> lxc-user-nic install 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.
Reference: https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1783591 Signed-off-by: Virendra Thakur <[email protected]> --- .../lxc/files/CVE-2022-47952.patch | 74 +++++++++++++++++++ recipes-containers/lxc/lxc_4.0.9.bb | 1 + 2 files changed, 75 insertions(+) create mode 100644 recipes-containers/lxc/files/CVE-2022-47952.patch diff --git a/recipes-containers/lxc/files/CVE-2022-47952.patch b/recipes-containers/lxc/files/CVE-2022-47952.patch new file mode 100644 index 0000000..eca2ad6 --- /dev/null +++ b/recipes-containers/lxc/files/CVE-2022-47952.patch @@ -0,0 +1,74 @@ +From 1b0469530d7a38b8f8990e114b52530d1bf7f3b8 Mon Sep 17 00:00:00 2001 +From: Maher Azzouzi <[email protected]> +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! + +Signed-off-by: MaherAzzouzi <[email protected]> +Acked-by: Serge Hallyn <[email protected]> + +Upstream-Status: Backport [https://github.com/lxc/lxc/commit/1b0469530d7a38b8f8990e114b52530d1bf7f3b8] +CVE: CVE-2022-47952 +Comment: No Hunk refreshed +Signed-off-by: Virendra Thakur <[email protected]> +--- + 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 a91e2259d5..69bc6f17d1 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); + } diff --git a/recipes-containers/lxc/lxc_4.0.9.bb b/recipes-containers/lxc/lxc_4.0.9.bb index f7cab78..7240589 100644 --- a/recipes-containers/lxc/lxc_4.0.9.bb +++ b/recipes-containers/lxc/lxc_4.0.9.bb @@ -55,6 +55,7 @@ SRC_URI = "http://linuxcontainers.org/downloads/${BPN}/${BPN}-${PV}.tar.gz \ file://skip_rootfs_pinning_for_read_only_filesystem.patch \ file://add_lxc_init_groups_config_key.patch \ file://lxc-conf-improve-read-only-sys-with-read-write-sys-devic.patch \ + file://CVE-2022-47952.patch \ " SRC_URI[md5sum] = "365fcca985038910e19a1e0fff15ed07" -- 2.17.1
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