[libvirt] [PATCH v4 09/11] security: Label the external swtpm with SELinux labels

[Stefan Berger]

On 05/15/2018 11:38 AM, Marc Hartmayer wrote:
> On Thu, May 10, 2018 at 11:57 PM +0200, Stefan Berger <stefanb at linux.vnet.ibm.com> wrote:
>> In this patch we label the swtpm process with SELinux labels. We give it the
>> same label as the QEMU process has. We label its state directory and files
>> as well. We restore the old security labels once the swtpm has terminated.
>>
>> The file and process labels now look as follows:
>>
>> Directory: /var/lib/libvirt/swtpm
>>
>> [root at localhost swtpm]# ls -lZ
>> total 4
>> rwx------. 2 tss  tss  system_u:object_r:svirt_image_t:s0:c254,c932 4096 Apr  5 16:46 testvm
>>
>> [root at localhost testvm]# ls -lZ
>> total 8
>> -rw-r--r--. 1 tss tss system_u:object_r:svirt_image_t:s0:c254,c932 3648 Apr  5 16:46 tpm-00.permall
>>
>> The log in /var/log/swtpm/libvirt/qemu is labeled as follows:
>>
>> -rw-r--r--. 1 tss tss system_u:object_r:svirt_image_t:s0:c254,c932 2237 Apr  5 16:46 vtpm.log
>>
>> [root at localhost 485d0004-a48f-436a-8457-8a3b73e28567]# ps auxZ | grep swtpm | grep ctrl | grep -v grep
>> system_u:system_r:svirt_t:s0:c254,c932 tss 25664 0.0  0.0 28172  3892 ?        Ss   16:57   0:00 /usr/bin/swtpm socket --daemon --ctrl type=unixio,path=/var/run/libvirt/qemu/swtpm/testvm-swtpm.sock,mode=0660 --tpmstate dir=/var/lib/libvirt/swtpm/testvm/tpm1.2 --log file=/var/log/swtpm/libvirt/qemu/testvm-swtpm.log
>>
>> [root at localhost 485d0004-a48f-436a-8457-8a3b73e28567]# ps auxZ | grep qemu | grep tpm | grep -v grep
>> system_u:system_r:svirt_t:s0:c254,c932 qemu 25669 99.0  0.0 3096704 48500 ?    Sl   16:57   3:28 /bin/qemu-system-x86_64 [..]
>>
>> Signed-off-by: Stefan Berger <stefanb at linux.vnet.ibm.com>
>> ---
>>   src/libvirt_private.syms        |   2 +
>>   src/qemu/qemu_tpm.c             |  24 +++++-
>>   src/security/security_driver.h  |   7 ++
>>   src/security/security_manager.c |  36 +++++++++
>>   src/security/security_manager.h |   6 ++
>>   src/security/security_selinux.c | 164 ++++++++++++++++++++++++++++++++++++++++
>>   src/security/security_stack.c   |  40 ++++++++++
>>   7 files changed, 278 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>> index 75b8932..2ce67e7 100644
>> --- a/src/libvirt_private.syms
>> +++ b/src/libvirt_private.syms
>> @@ -1319,6 +1319,7 @@ virSecurityManagerRestoreImageLabel;
>>   virSecurityManagerRestoreInputLabel;
>>   virSecurityManagerRestoreMemoryLabel;
>>   virSecurityManagerRestoreSavedStateLabel;
>> +virSecurityManagerRestoreTPMLabels;
>>   virSecurityManagerSetAllLabel;
>>   virSecurityManagerSetChardevLabel;
>>   virSecurityManagerSetChildProcessLabel;
>> @@ -1333,6 +1334,7 @@ virSecurityManagerSetProcessLabel;
>>   virSecurityManagerSetSavedStateLabel;
>>   virSecurityManagerSetSocketLabel;
>>   virSecurityManagerSetTapFDLabel;
>> +virSecurityManagerSetTPMLabels;
>>   virSecurityManagerStackAddNested;
>>   virSecurityManagerTransactionAbort;
>>   virSecurityManagerTransactionCommit;
>> diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c
>> index 024d24d..62f0146 100644
>> --- a/src/qemu/qemu_tpm.c
>> +++ b/src/qemu/qemu_tpm.c
>> @@ -684,7 +684,26 @@ qemuExtTPMStartEmulator(virQEMUDriverPtr driver,
>>
>>       virCommandSetErrorBuffer(cmd, &errbuf);
>>
>> -    if (virCommandRun(cmd, &exitstatus) < 0 || exitstatus != 0) {
>> +    if (virSecurityManagerSetTPMLabels(driver->securityManager,
>> +                                       def) < 0)
>> +        goto cleanup;
>> +
>> +    if (virSecurityManagerSetChildProcessLabel(driver->securityManager,
>> +                                               def, cmd) < 0)
>> +        goto cleanup;
>> +
>> +    if (virSecurityManagerPreFork(driver->securityManager) < 0)
>> +        goto cleanup;
>> +
>> +    /* make sure we run this with the appropriate user */
>> +    virCommandSetUID(cmd, cfg->swtpm_user);
>> +    virCommandSetGID(cmd, cfg->swtpm_group);
>> +
>> +    ret = virCommandRun(cmd, &exitstatus);
>> +
>> +    virSecurityManagerPostFork(driver->securityManager);
>> +
>> +    if (ret < 0 || exitstatus != 0) {
>>           VIR_ERROR(_("Could not start 'swtpm'. exitstatus: %d "
>>                       "stderr: %s"), exitstatus, errbuf);
>>           virReportError(VIR_ERR_INTERNAL_ERROR,
> Don't we have to set ret to -1 here (for the case where ret == 0 &&
> exitstatus != 0)?

Very true.

   Stefan