9pfs: fix vulnerability in openat_dir() and local_unlinkat_common()
We should pass O_NOFOLLOW otherwise openat() will follow symlinks and make
QEMU vulnerable.
While here, we also fix local_unlinkat_common() to use openat_dir() for
the same reasons (it was a leftover in the original patchset actually).
This fixes CVE-2016-9602.
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 0ca4c94..45e9a1f 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -960,7 +960,7 @@
if (flags == AT_REMOVEDIR) {
int fd;
- fd = openat(dirfd, name, O_RDONLY | O_DIRECTORY | O_PATH);
+ fd = openat_dir(dirfd, name);
if (fd == -1) {
goto err_out;
}
diff --git a/hw/9pfs/9p-util.h b/hw/9pfs/9p-util.h
index cb7b207..517027c 100644
--- a/hw/9pfs/9p-util.h
+++ b/hw/9pfs/9p-util.h
@@ -27,7 +27,8 @@
#else
#define OPENAT_DIR_O_PATH 0
#endif
- return openat(dirfd, name, O_DIRECTORY | O_RDONLY | OPENAT_DIR_O_PATH);
+ return openat(dirfd, name,
+ O_DIRECTORY | O_RDONLY | O_NOFOLLOW | OPENAT_DIR_O_PATH);
}
static inline int openat_file(int dirfd, const char *name, int flags,
