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Re: [libvirt] [PATCH 2/2] LXC: introduce lxcContainerUnmountForSharedRoot



On 09/11/2013 04:00 PM, Gao feng wrote:
> Move the unmounting private or useless filesystem of host
> to this function.
> 
> Signed-off-by: Gao feng <gaofeng cn fujitsu com>
> ---

I forgot to remove the "tmp" in lxcContainerSetupPivotRoot,a new patchset
will come soon.

>  src/lxc/lxc_container.c | 96 ++++++++++++++++++++++++++++---------------------
>  1 file changed, 55 insertions(+), 41 deletions(-)
> 
> diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
> index 0ab4ab7..1423b6d 100644
> --- a/src/lxc/lxc_container.c
> +++ b/src/lxc/lxc_container.c
> @@ -1472,6 +1472,60 @@ cleanup:
>  }
>  
>  
> +static int lxcContainerUnmountForSharedRoot(const char *stateDir,
> +                                            const char *domain)
> +{
> +    int ret = -1;
> +    char *tmp = NULL;
> +
> +#if WITH_SELINUX
> +    /* Some versions of Linux kernel don't let you overmount
> +     * the selinux filesystem, so make sure we kill it first
> +     */
> +    /* Filed coverity bug for false positive 'USE_AFTER_FREE' due to swap
> +     * of root->src with root->dst and the VIR_FREE(root->src) prior to the
> +     * reset of root->src in lxcContainerPrepareRoot()
> +     */
> +    /* coverity[deref_arg] */
> +    if (lxcContainerUnmountSubtree(SELINUX_MOUNT, false) < 0)
> +        goto cleanup;
> +#endif
> +
> +    /* These filesystems are created by libvirt temporarily, they
> +     * shouldn't appear in container. */
> +    if (virAsprintf(&tmp, "%s/%s.dev", stateDir, domain) < 0 ||
> +        lxcContainerUnmountSubtree(tmp, false) < 0)
> +        goto cleanup;
> +
> +    VIR_FREE(tmp);
> +    if (virAsprintf(&tmp, "%s/%s.devpts", stateDir, domain) < 0 ||
> +        lxcContainerUnmountSubtree(tmp, false) < 0)
> +        goto cleanup;
> +
> +#if WITH_FUSE
> +    VIR_FREE(tmp);
> +    if (virAsprintf(&tmp, "%s/%s.fuse", stateDir, domain) < 0 ||
> +        lxcContainerUnmountSubtree(tmp, false) < 0)
> +        goto cleanup;
> +#endif
> +
> +    /* If we have the root source being '/', then we need to
> +     * get rid of any existing stuff under /proc, /sys & /tmp.
> +     * We need new namespace aware versions of those. We must
> +     * do /proc last otherwise we won't find /proc/mounts :-) */
> +    if (lxcContainerUnmountSubtree("/sys", false) < 0 ||
> +        lxcContainerUnmountSubtree("/dev", false) < 0 ||
> +        lxcContainerUnmountSubtree("/proc", false) < 0)
> +        goto cleanup;
> +
> +    ret = 0;
> +
> +cleanup:
> +    VIR_FREE(tmp);
> +    return ret;
> +}
> +
> +
>  /* Got a FS mapped to /, we're going the pivot_root
>   * approach to do a better-chroot-than-chroot
>   * this is based on this thread http://lkml.org/lkml/2008/3/5/29
> @@ -1509,48 +1563,8 @@ static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
>      if (lxcContainerPivotRoot(root) < 0)
>          goto cleanup;
>  
> -#if WITH_SELINUX
> -    /* Some versions of Linux kernel don't let you overmount
> -     * the selinux filesystem, so make sure we kill it first
> -     */
> -    /* Filed coverity bug for false positive 'USE_AFTER_FREE' due to swap
> -     * of root->src with root->dst and the VIR_FREE(root->src) prior to the
> -     * reset of root->src in lxcContainerPrepareRoot()
> -     */
> -    /* coverity[deref_arg] */
> -    if (STREQ(root->src, "/") &&
> -        lxcContainerUnmountSubtree(SELINUX_MOUNT, false) < 0)
> -        goto cleanup;
> -#endif
> -
> -    /* These filesystems are created by libvirt temporarily, they
> -     * shouldn't appear in container. */
> -    if (STREQ(root->src, "/")) {
> -        if (virAsprintf(&tmp, "%s/%s.dev", stateDir, vmDef->name) < 0 ||
> -            lxcContainerUnmountSubtree(tmp, false) < 0)
> -            goto cleanup;
> -
> -        VIR_FREE(tmp);
> -        if (virAsprintf(&tmp, "%s/%s.devpts", stateDir, vmDef->name) < 0 ||
> -            lxcContainerUnmountSubtree(tmp, false) < 0)
> -            goto cleanup;
> -
> -#if WITH_FUSE
> -        VIR_FREE(tmp);
> -        if (virAsprintf(&tmp, "%s/%s.fuse", stateDir, vmDef->name) < 0 ||
> -            lxcContainerUnmountSubtree(tmp, false) < 0)
> -            goto cleanup;
> -#endif
> -    }
> -
> -    /* If we have the root source being '/', then we need to
> -     * get rid of any existing stuff under /proc, /sys & /tmp.
> -     * We need new namespace aware versions of those. We must
> -     * do /proc last otherwise we won't find /proc/mounts :-) */
>      if (STREQ(root->src, "/") &&
> -        (lxcContainerUnmountSubtree("/sys", false) < 0 ||
> -         lxcContainerUnmountSubtree("/dev", false) < 0 ||
> -         lxcContainerUnmountSubtree("/proc", false) < 0))
> +        lxcContainerUnmountForSharedRoot(stateDir, vmDef->name) < 0)
>          goto cleanup;
>  
>      /* Mounts the core /proc, /sys, etc filesystems */
> 


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