Re: [Qemu-devel] [PATCH 5/6] vnc: allow specifying a custom authorization object name

[Daniel P . Berrangé]

On Fri, Jun 15, 2018 at 04:51:02PM +0100, Daniel P. Berrangé wrote:
> From: "Daniel P. Berrange" <address@hidden>
> 
> The VNC server has historically had support for ACLs to check both the
> SASL username and the TLS x509 distinguished name. The VNC server was
> responsible for creating the initial ACL, and the client app was then
> responsible for populating it with rules using the HMP 'acl_add' command.
> 
> This is not satisfactory for a variety of reasons. There is no way to
> populate the ACLs from the command line, users are forced to use the
> HMP. With multiple network services all supporting TLS and ACLs now, it
> is desirable to be able to define a single ACL that is referenced by all
> services.
> 
> To address these limitations, two new options are added to the VNC
> server CLI. The 'tls-authz' option takes the ID of a QAuthZ object to
> use for checking TLS x509 distinguished names, and the 'sasl-authz'
> option takes the ID of another object to use for checking SASL usernames.
> 
> In this example, we setup two authorization rules. The first allows any
> client with a certificate issued by the 'RedHat' organization in the
> 'London' locality. The second ACL allows clients with either the
> 'address@hidden' or  'address@hidden' kerberos usernames. Both checks
> must pass for the user to be allowed.
> 
>     $QEMU -object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
>                   endpoint=server,verify-peer=yes \
>           -object authz-simple,id=authz0,policy=deny,\
>                   rules.0.match=O=RedHat,,L=London,rules.0.policy=allow \
>           -object authz-simple,id=authz1,policy=deny,\
>                   address@hidden,rules.0.policy=allow \
>                   address@hidden,rules.0.policy=allow \

Opps this msg is outdated, since we don't have ability to express
such nested properties with -object since I dropped my hacky impl
of that.

>           -vnc 0.0.0.0:1,tls-creds=tls0,tls-authz=authz0,
>              sasl,sasl-authz=authz1 \
>           ...other QEMU args...
> 
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
>  qemu-doc.texi | 11 +++-------
>  ui/vnc.c      | 58 +++++++++++++++++++++++++++++++++++++++++++--------
>  2 files changed, 52 insertions(+), 17 deletions(-)
> 
> diff --git a/qemu-doc.texi b/qemu-doc.texi
> index cd05760cac..5b7e3faab2 100644
> --- a/qemu-doc.texi
> +++ b/qemu-doc.texi
> @@ -2917,15 +2917,10 @@ The @code{-localtime} option has been replaced by 
> @code{-rtc base=localtime}.
>  
>  The @code{-startdate} option has been replaced by @code{-rtc address@hidden
>  
> address@hidden -virtioconsole (since 3.0.0)
> address@hidden -vnc acl (since 3.0.0)
>  
> -Option @option{-virtioconsole} has been replaced by
> address@hidden virtconsole}.
> -
> address@hidden -clock (since 3.0.0)
> -
> -The @code{-clock} option is ignored since QEMU version 1.7.0. There is no
> -replacement since it is not needed anymore.
> +The @code{acl} option to the @code{-vnc} argument has been replaced
> +by the @code{tls-authz} and @code{sasl-authz} options.
>  
>  @section QEMU Machine Protocol (QMP) commands
>  
> diff --git a/ui/vnc.c b/ui/vnc.c
> index 9fb8430c35..2da9433ca7 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -3407,6 +3407,12 @@ static QemuOptsList qemu_vnc_opts = {
>          },{
>              .name = "acl",
>              .type = QEMU_OPT_BOOL,
> +        },{
> +            .name = "tls-authz",
> +            .type = QEMU_OPT_STRING,
> +        },{
> +            .name = "sasl-authz",
> +            .type = QEMU_OPT_STRING,
>          },{
>              .name = "lossy",
>              .type = QEMU_OPT_BOOL,
> @@ -3894,6 +3900,8 @@ void vnc_display_open(const char *id, Error **errp)
>      int saslErr;
>  #endif
>      int acl = 0;
> +    const char *tlsauthz;
> +    const char *saslauthz;
>      int lock_key_sync = 1;
>      int key_delay_ms;
>  
> @@ -3999,7 +4007,33 @@ void vnc_display_open(const char *id, Error **errp)
>              }
>          }
>      }
> +    if (qemu_opt_get(opts, "acl")) {
> +        error_report("The 'acl' option to -vnc is deprecated. "
> +                     "Please use the 'tls-authz' and 'sasl-authz' "
> +                     "options instead");
> +    }
>      acl = qemu_opt_get_bool(opts, "acl", false);
> +    tlsauthz = qemu_opt_get(opts, "tls-authz");
> +    if (acl && tlsauthz) {
> +        error_setg(errp, "'acl' option is mutually exclusive with the "
> +                   "'tls-authz' option");
> +        goto fail;
> +    }
> +    if (tlsauthz && !vd->tlscreds) {
> +        error_setg(errp, "'tls-authz' provided but TLS is not enabled");
> +        goto fail;
> +    }
> +
> +    saslauthz = qemu_opt_get(opts, "sasl-authz");
> +    if (acl && saslauthz) {
> +        error_setg(errp, "'acl' option is mutually exclusive with the "
> +                   "'sasl-authz' option");
> +        goto fail;
> +    }
> +    if (saslauthz && !sasl) {
> +        error_setg(errp, "'sasl-authz' provided but SASL auth is not 
> enabled");
> +        goto fail;
> +    }
>  
>      share = qemu_opt_get(opts, "share");
>      if (share) {
> @@ -4029,7 +4063,9 @@ void vnc_display_open(const char *id, Error **errp)
>          vd->non_adaptive = true;
>      }
>  
> -    if (acl) {
> +    if (tlsauthz) {
> +        vd->tlsauthzid = g_strdup(tlsauthz);
> +    } else if (acl) {
>          if (strcmp(vd->id, "default") == 0) {
>              vd->tlsauthzid = g_strdup("vnc.x509dname");
>          } else {
> @@ -4040,15 +4076,19 @@ void vnc_display_open(const char *id, Error **errp)
>                                                &error_abort));
>      }
>  #ifdef CONFIG_VNC_SASL
> -    if (acl && sasl) {
> -        if (strcmp(vd->id, "default") == 0) {
> -            vd->sasl.authzid = g_strdup("vnc.username");
> -        } else {
> -            vd->sasl.authzid = g_strdup_printf("vnc.%s.username", vd->id);
> +    if (sasl) {
> +        if (saslauthz) {
> +            vd->sasl.authzid = g_strdup(saslauthz);
> +        } else if (acl) {
> +            if (strcmp(vd->id, "default") == 0) {
> +                vd->sasl.authzid = g_strdup("vnc.username");
> +            } else {
> +                vd->sasl.authzid = g_strdup_printf("vnc.%s.username", 
> vd->id);
> +            }
> +            vd->sasl.authz = QAUTHZ(qauthz_list_new(vd->sasl.authzid,
> +                                                    QAUTHZ_LIST_POLICY_DENY,
> +                                                    &error_abort));
>          }
> -        vd->sasl.authz = QAUTHZ(qauthz_list_new(vd->sasl.authzid,
> -                                                QAUTHZ_LIST_POLICY_DENY,
> -                                                &error_abort));
>      }
>  #endif
>  
> -- 
> 2.17.0
> 

Regards,
Daniel
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