[libvirt] [PATCH 3/5] qemu_conf: add new configuration key bridge_helper

[Laine Stump]

On 03/25/2013 10:25 AM, Paolo Bonzini wrote:
> Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
> ---
>  src/qemu/libvirtd_qemu.aug         | 1 +
>  src/qemu/qemu.conf                 | 8 ++++++++
>  src/qemu/qemu_conf.c               | 3 +++
>  src/qemu/qemu_conf.h               | 1 +
>  src/qemu/test_libvirtd_qemu.aug.in | 1 +
>  5 files changed, 14 insertions(+)
>
> diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
> index 91f5f77..61740a9 100644
> --- a/src/qemu/libvirtd_qemu.aug
> +++ b/src/qemu/libvirtd_qemu.aug
> @@ -60,6 +60,7 @@ module Libvirtd_qemu =
>  
>     let process_entry = str_entry "hugetlbfs_mount"
>                   | bool_entry "clear_emulator_capabilities"
> +                 | str_entry "bridge_helper"
>                   | bool_entry "set_process_name"
>                   | int_entry "max_processes"
>                   | int_entry "max_files"
> diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
> index dd853c8..87bdf70 100644
> --- a/src/qemu/qemu.conf
> +++ b/src/qemu/qemu.conf
> @@ -301,6 +301,14 @@
>  #hugetlbfs_mount = "/dev/hugepages"
>  
>  
> +# Path to the setuid helper for creating tap devices.  This executable
> +# is used to create <source type='bridge'> interfaces when libvirtd is
> +# running unprivileged.  libvirt invokes the helper directly, instead
> +# of using "-netdev bridge", for security reasons.
> +#bridge_helper = "/usr/libexec/qemu-bridge-helper"
> +
> +

Are we sure we want to allow this to be configured? That could lead to
some "interesting" troubleshooting incidents :-)

On the other hand, I guess the path to qemu itself is right there in the
domain config file, so how much worse could this be...


> +
>  # If clear_emulator_capabilities is enabled, libvirt will drop all
>  # privileged capabilities of the QEmu/KVM emulator. This is enabled by
>  # default.
> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
> index c2e2e10..f648fc3 100644
> --- a/src/qemu/qemu_conf.c
> +++ b/src/qemu/qemu_conf.c
> @@ -248,6 +248,7 @@ virQEMUDriverConfigPtr virQEMUDriverConfigNew(bool privileged)
>          }
>      }
>  #endif
> +    cfg->bridgeHelperName = strdup("/usr/libexec/qemu-bridge-helper");
>  
>      cfg->clearEmulatorCapabilities = true;
>  
> @@ -297,6 +298,7 @@ static void virQEMUDriverConfigDispose(void *obj)
>  
>      VIR_FREE(cfg->hugetlbfsMount);
>      VIR_FREE(cfg->hugepagePath);
> +    VIR_FREE(cfg->bridgeHelperName);
>  
>      VIR_FREE(cfg->saveImageFormat);
>      VIR_FREE(cfg->dumpImageFormat);
> @@ -509,6 +511,7 @@ int virQEMUDriverConfigLoadFile(virQEMUDriverConfigPtr cfg,
>      GET_VALUE_BOOL("auto_start_bypass_cache", cfg->autoStartBypassCache);
>  
>      GET_VALUE_STR("hugetlbfs_mount", cfg->hugetlbfsMount);
> +    GET_VALUE_STR("bridge_helper", cfg->bridgeHelperName);
>  
>      GET_VALUE_BOOL("mac_filter", cfg->macFilter);
>  
> diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
> index c5ddaad..666ac33 100644
> --- a/src/qemu/qemu_conf.h
> +++ b/src/qemu/qemu_conf.h
> @@ -117,6 +117,7 @@ struct _virQEMUDriverConfig {
>  
>      char *hugetlbfsMount;
>      char *hugepagePath;
> +    char *bridgeHelperName;
>  
>      bool macFilter;
>  
> diff --git a/src/qemu/test_libvirtd_qemu.aug.in b/src/qemu/test_libvirtd_qemu.aug.in
> index 2892204..0aec997 100644
> --- a/src/qemu/test_libvirtd_qemu.aug.in
> +++ b/src/qemu/test_libvirtd_qemu.aug.in
> @@ -49,6 +49,7 @@ module Test_libvirtd_qemu =
>  { "auto_dump_bypass_cache" = "0" }
>  { "auto_start_bypass_cache" = "0" }
>  { "hugetlbfs_mount" = "/dev/hugepages" }
> +{ "bridge_helper" = "/usr/libexec/qemu-bridge-helper" }
>  { "clear_emulator_capabilities" = "1" }
>  { "set_process_name" = "1" }
>  { "max_processes" = "0" }

ACK. (But I'd like at least one other ACK from someone else due to the
fact that this is polluting the config namespace with something we would
like to eventually eliminate.)