[libvirt] [PATCH v2 8/8] qemu: support use of virtlogd with file based chardevs

[John Ferlan]

On 02/29/2016 08:33 AM, Daniel P. Berrange wrote:
> Currently the file based character devices let QEMU write
> directly to a file on disk. This allows a malicious QEMU
> to inflict a denial of service by consuming all free space.
> 
> Switch QEMU to use a pipe to virtlogd, which will enforce
> file rollover.
> 
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>  src/qemu/qemu_command.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index e04e55e..462a019 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -3983,18 +3983,19 @@ qemuBuildChrChardevStr(virLogManagerPtr logManager,
>          break;
>  
>      case VIR_DOMAIN_CHR_TYPE_FILE:
> -        virBufferAsprintf(&buf, "file,id=char%s,path=%s", alias,
                                                   ^^^^

(see below)

> -                          dev->data.file.path);
> -        if (dev->data.file.append != VIR_TRISTATE_SWITCH_ABSENT) {
> -            if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_CHARDEV_FILE_APPEND)) {
> -                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> -                               _("append not supported in this QEMU binary"));
> -                goto error;
> -            }
> +        virBufferAsprintf(&buf, "file,id=char%s", alias);
>  
> -            virBufferAsprintf(&buf, ",append=%s",
> -                              virTristateSwitchTypeToString(dev->data.file.append));
> +        if (dev->data.file.append != VIR_TRISTATE_SWITCH_ABSENT &&
> +            !virQEMUCapsGet(qemuCaps, QEMU_CAPS_CHARDEV_FILE_APPEND)) {
> +            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                           _("append not supported in this QEMU binary"));
> +            goto error;
>          }
> +        if (qemuBuildChrChardevFileStr(virQEMUCapsGet(qemuCaps, QEMU_CAPS_CHARDEV_FILE_APPEND) ?
> +                                       logManager : NULL, cmd, def, &buf,
> +                                       "file", dev->data.file.path,

s/"file"/"path" ?

> +                                       "append", dev->data.file.append) < 0)
> +            goto error;
>          break;
>  
>      case VIR_DOMAIN_CHR_TYPE_PIPE:
>