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authorPaolo Bonzini <pbonzini@redhat.com>2015-11-27 12:43:05 +0100
committerGreg Kurz <gkurz@linux.vnet.ibm.com>2015-11-30 12:31:53 +0100
commit49f817caaf4460f4a8dfca190f31a57569fc9efe (patch)
treecffe0b89c1206068620cf290c08079117cce6963
parent714487515dbe0c65d5904251e796cd3a5b3579fb (diff)
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fsdev-proxy-helper: avoid TOC/TOU race
There is a minor time of check/time of use race between statfs and chroot. It can be fixed easily by stat-ing the root after it has been changed. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
-rw-r--r--fsdev/virtfs-proxy-helper.c20
1 files changed, 10 insertions, 10 deletions
diff --git a/fsdev/virtfs-proxy-helper.c b/fsdev/virtfs-proxy-helper.c
index 9097d15..ad1da0d 100644
--- a/fsdev/virtfs-proxy-helper.c
+++ b/fsdev/virtfs-proxy-helper.c
@@ -1128,10 +1128,19 @@ int main(int argc, char **argv)
}
}
+ if (chdir("/") < 0) {
+ do_perror("chdir");
+ goto error;
+ }
+ if (chroot(rpath) < 0) {
+ do_perror("chroot");
+ goto error;
+ }
+
get_version = false;
#ifdef FS_IOC_GETVERSION
/* check whether underlying FS support IOC_GETVERSION */
- retval = statfs(rpath, &st_fs);
+ retval = statfs("/", &st_fs);
if (!retval) {
switch (st_fs.f_type) {
case EXT2_SUPER_MAGIC:
@@ -1144,16 +1153,7 @@ int main(int argc, char **argv)
}
#endif
- if (chdir("/") < 0) {
- do_perror("chdir");
- goto error;
- }
- if (chroot(rpath) < 0) {
- do_perror("chroot");
- goto error;
- }
umask(0);
-
if (init_capabilities() < 0) {
goto error;
}