diff options
Diffstat (limited to 'meta/recipes-devtools/qemu/qemu/CVE-2023-2861.patch')
| -rw-r--r-- | meta/recipes-devtools/qemu/qemu/CVE-2023-2861.patch | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2023-2861.patch b/meta/recipes-devtools/qemu/qemu/CVE-2023-2861.patch new file mode 100644 index 0000000000..70b7d6c562 --- /dev/null +++ b/meta/recipes-devtools/qemu/qemu/CVE-2023-2861.patch @@ -0,0 +1,178 @@ +From f6b0de53fb87ddefed348a39284c8e2f28dc4eda Mon Sep 17 00:00:00 2001 +From: Christian Schoenebeck <qemu_oss@crudebyte.com> +Date: Wed, 7 Jun 2023 18:29:33 +0200 +Subject: [PATCH] 9pfs: prevent opening special files (CVE-2023-2861) + +The 9p protocol does not specifically define how server shall behave when +client tries to open a special file, however from security POV it does +make sense for 9p server to prohibit opening any special file on host side +in general. A sane Linux 9p client for instance would never attempt to +open a special file on host side, it would always handle those exclusively +on its guest side. A malicious client however could potentially escape +from the exported 9p tree by creating and opening a device file on host +side. + +With QEMU this could only be exploited in the following unsafe setups: + + - Running QEMU binary as root AND 9p 'local' fs driver AND 'passthrough' + security model. + +or + + - Using 9p 'proxy' fs driver (which is running its helper daemon as + root). + +These setups were already discouraged for safety reasons before, +however for obvious reasons we are now tightening behaviour on this. + +Fixes: CVE-2023-2861 +Reported-by: Yanwu Shen <ywsPlz@gmail.com> +Reported-by: Jietao Xiao <shawtao1125@gmail.com> +Reported-by: Jinku Li <jkli@xidian.edu.cn> +Reported-by: Wenbo Shen <shenwenbo@zju.edu.cn> +Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> +Reviewed-by: Greg Kurz <groug@kaod.org> +Reviewed-by: Michael Tokarev <mjt@tls.msk.ru> +Message-Id: <E1q6w7r-0000Q0-NM@lizzy.crudebyte.com> + +Upstream-Status: Backport [https://gitlab.com/qemu-project/qemu/-/commit/f6b0de53fb87ddefed348a39284c8e2f28dc4eda] +CVE: CVE-2023-2861 +Signed-off-by: Vijay Anusuri <vanusuri@mvista.com> +--- + fsdev/virtfs-proxy-helper.c | 27 +++++++++++++++++++++++-- + hw/9pfs/9p-util.h | 40 +++++++++++++++++++++++++++++++++++++ + 2 files changed, 65 insertions(+), 2 deletions(-) + +diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c +index 6f132c5f..300c9765 100644 +--- a/fsdev/virtfs-proxy-helper.c ++++ b/fsdev/virtfs-proxy-helper.c +@@ -26,6 +26,7 @@ + #include "qemu/xattr.h" + #include "9p-iov-marshal.h" + #include "hw/9pfs/9p-proxy.h" ++#include "hw/9pfs/9p-util.h" + #include "fsdev/9p-iov-marshal.h" + + #define PROGNAME "virtfs-proxy-helper" +@@ -350,6 +351,28 @@ static void resetugid(int suid, int sgid) + } + } + ++/* ++ * Open regular file or directory. Attempts to open any special file are ++ * rejected. ++ * ++ * returns file descriptor or -1 on error ++ */ ++static int open_regular(const char *pathname, int flags, mode_t mode) ++{ ++ int fd; ++ ++ fd = open(pathname, flags, mode); ++ if (fd < 0) { ++ return fd; ++ } ++ ++ if (close_if_special_file(fd) < 0) { ++ return -1; ++ } ++ ++ return fd; ++} ++ + /* + * send response in two parts + * 1) ProxyHeader +@@ -694,7 +717,7 @@ static int do_create(struct iovec *iovec) + if (ret < 0) { + goto unmarshal_err_out; + } +- ret = open(path.data, flags, mode); ++ ret = open_regular(path.data, flags, mode); + if (ret < 0) { + ret = -errno; + } +@@ -719,7 +742,7 @@ static int do_open(struct iovec *iovec) + if (ret < 0) { + goto err_out; + } +- ret = open(path.data, flags); ++ ret = open_regular(path.data, flags, 0); + if (ret < 0) { + ret = -errno; + } +diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h +index 546f46dc..79fdd2a3 100644 +--- a/hw/9pfs/9p-util.h ++++ b/hw/9pfs/9p-util.h +@@ -13,12 +13,16 @@ + #ifndef QEMU_9P_UTIL_H + #define QEMU_9P_UTIL_H + ++#include "qemu/error-report.h" ++ + #ifdef O_PATH + #define O_PATH_9P_UTIL O_PATH + #else + #define O_PATH_9P_UTIL 0 + #endif + ++#define qemu_fstat fstat ++ + static inline void close_preserve_errno(int fd) + { + int serrno = errno; +@@ -26,6 +30,38 @@ static inline void close_preserve_errno(int fd) + errno = serrno; + } + ++/** ++ * close_if_special_file() - Close @fd if neither regular file nor directory. ++ * ++ * @fd: file descriptor of open file ++ * Return: 0 on regular file or directory, -1 otherwise ++ * ++ * CVE-2023-2861: Prohibit opening any special file directly on host ++ * (especially device files), as a compromised client could potentially gain ++ * access outside exported tree under certain, unsafe setups. We expect ++ * client to handle I/O on special files exclusively on guest side. ++ */ ++static inline int close_if_special_file(int fd) ++{ ++ struct stat stbuf; ++ ++ if (qemu_fstat(fd, &stbuf) < 0) { ++ close_preserve_errno(fd); ++ return -1; ++ } ++ if (!S_ISREG(stbuf.st_mode) && !S_ISDIR(stbuf.st_mode)) { ++ error_report_once( ++ "9p: broken or compromised client detected; attempt to open " ++ "special file (i.e. neither regular file, nor directory)" ++ ); ++ close(fd); ++ errno = ENXIO; ++ return -1; ++ } ++ ++ return 0; ++} ++ + static inline int openat_dir(int dirfd, const char *name) + { + return openat(dirfd, name, +@@ -56,6 +92,10 @@ again: + return -1; + } + ++ if (close_if_special_file(fd) < 0) { ++ return -1; ++ } ++ + serrno = errno; + /* O_NONBLOCK was only needed to open the file. Let's drop it. We don't + * do that with O_PATH since fcntl(F_SETFL) isn't supported, and openat() +-- +2.25.1 + |