Commit 49f817ca authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Greg Kurz
Browse files

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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarGreg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: default avatarGreg Kurz <gkurz@linux.vnet.ibm.com>
parent 71448751

fsdev/virtfs-proxy-helper.c

+10 −10
Original line number Diff line number Diff line
@@ -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;

    }