Re: [PULL 3/5] crypto/linux_keyring: add 'secret_keyring' secret object.

[Daniel P . Berrangé]

On Fri, May 29, 2020 at 11:35:53AM +0100, Daniel P. Berrangé wrote:
> From: Alexey Krasikov <alex-krasikov@yandex-team.ru>
> 
> Add the ability for the secret object to obtain secret data from the
> Linux in-kernel key managment and retention facility, as an extra option
> to the existing ones: reading from a file or passing directly as a
> string.
> 
> The secret is identified by the key serial number. The upper layers
> need to instantiate the key and make sure the QEMU process has access
> permissions to read it.
> 
> Signed-off-by: Alexey Krasikov <alex-krasikov@yandex-team.ru>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  configure                       |  38 ++++++++
>  crypto/Makefile.objs            |   1 +
>  crypto/secret_keyring.c         | 148 ++++++++++++++++++++++++++++++++
>  include/crypto/secret_keyring.h |  52 +++++++++++
>  4 files changed, 239 insertions(+)
>  create mode 100644 crypto/secret_keyring.c
>  create mode 100644 include/crypto/secret_keyring.h
> 
> diff --git a/configure b/configure
> index 2ffe365e2c..d95ff4e0b3 100755
> --- a/configure
> +++ b/configure
> @@ -510,6 +510,7 @@ default_devices="yes"
>  plugins="no"
>  fuzzing="no"
>  rng_none="no"
> +secret_keyring="yes"
>  
>  supported_cpu="no"
>  supported_os="no"
> @@ -1606,6 +1607,10 @@ for opt do
>    ;;
>    --disable-rng-none) rng_none=no
>    ;;
> +  --enable-keyring) secret_keyring="yes"
> +  ;;
> +  --disable-keyring) secret_keyring="no"
> +  ;;
>    *)
>        echo "ERROR: unknown option $opt"
>        echo "Try '$0 --help' for more information"
> @@ -6272,6 +6277,34 @@ case "$slirp" in
>      ;;
>  esac
>  
> +##########################################
> +# check for usable __NR_keyctl syscall
> +
> +if test "$linux" = "yes" ; then
> +
> +    have_keyring=no
> +    cat > $TMPC << EOF
> +#include <errno.h>
> +#include <asm/unistd.h>
> +#include <linux/keyctl.h>
> +#include <unistd.h>
> +int main(void) {
> +    return syscall(__NR_keyctl, KEYCTL_READ, 0, NULL, NULL, 0);
> +}
> +EOF
> +    if compile_prog "" "" ; then
> +        have_keyring=yes
> +    fi
> +fi
> +if test "$secret_keyring" = "yes"
> +then
> +    if test "$have_keyring" != "yes"
> +    then
> +    error_exit "syscall __NR_keyctl requested, \
> +but not implemented on your system"
> +    fi
> +fi

This logic doesn't correctly disable keyring on Non-Linux native
builds by default. eg mingw as reported by patchew

I'm going to repost with the following squashed in

diff --git a/configure b/configure
index f2ff722f7e..f17c2fd72e 100755
--- a/configure
+++ b/configure
@@ -510,7 +510,7 @@ default_devices="yes"
 plugins="no"
 fuzzing="no"
 rng_none="no"
-secret_keyring="yes"
+secret_keyring=""
 
 supported_cpu="no"
 supported_os="no"
@@ -6296,12 +6296,19 @@ EOF
         have_keyring=yes
     fi
 fi
-if test "$secret_keyring" = "yes"
+if test "$secret_keyring" != "no"
 then
-    if test "$have_keyring" != "yes"
+    if test "$have_keyring" == "yes"
     then
-    error_exit "syscall __NR_keyctl requested, \
+       secret_keyring=yes
+    else
+       if test "$secret_keyring" = "yes"
+       then
+           error_exit "syscall __NR_keyctl requested, \
 but not implemented on your system"
+       else
+           secret_keyring=no
+       fi
     fi
 fi


Regards,
Daniel
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