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Re: [libvirt] [PATCH v3 08/12] LXC: controller: change the owner of tty devices to the root user of container



On 05/23/2013 01:52 PM, Richard RW. Weinberger wrote:
> Hi!
> 
> ----- Urspr√ľngliche Mail -----
>> Since these tty devices will be used by container,
>> the owner of them should be the root user of container.
>>
>> Signed-off-by: Gao feng <gaofeng cn fujitsu com>
>> ---
>>  src/lxc/lxc_controller.c | 43
>>  +++++++++++++++++++++++++++++++++++++------
>>  1 file changed, 37 insertions(+), 6 deletions(-)
>>
>> diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
>> index 7d10660..4660f25 100644
>> --- a/src/lxc/lxc_controller.c
>> +++ b/src/lxc/lxc_controller.c
>> @@ -1380,13 +1380,14 @@ static int lxcSetPersonality(virDomainDefPtr
>> def)
>>   * *TTYNAME.  Heavily borrowed from glibc, but doesn't require that
>>   * devpts == "/dev/pts" */
>>  static int
>> -lxcCreateTty(char *ptmx, int *ttymaster, char **ttyName)
>> +lxcCreateTty(virLXCControllerPtr ctrl, int *ttymaster,
>> +             char **ttyName, char **ttyHostPath)
>>  {
>>      int ret = -1;
>>      int ptyno;
>>      int unlock = 0;
>>  
>> -    if ((*ttymaster = open(ptmx, O_RDWR|O_NOCTTY|O_NONBLOCK)) < 0)
>> +    if ((*ttymaster = open(ctrl->devptmx,
>> O_RDWR|O_NOCTTY|O_NONBLOCK)) < 0)
>>          goto cleanup;
>>  
>>      if (ioctl(*ttymaster, TIOCSPTLCK, &unlock) < 0)
>> @@ -1407,6 +1408,13 @@ lxcCreateTty(char *ptmx, int *ttymaster, char
>> **ttyName)
>>          goto cleanup;
>>      }
>>  
>> +    if (virAsprintf(ttyHostPath, "/%s/%s.devpts/%d", LXC_STATE_DIR,
>> +                    ctrl->def->name, ptyno) < 0) {
>> +        virReportOOMError();
>> +        errno = ENOMEM;
>> +        goto cleanup;
>> +    }
>> +
>>      ret = 0;
>>  
>>  cleanup:
>> @@ -1552,18 +1560,41 @@
>> virLXCControllerSetupConsoles(virLXCControllerPtr ctrl,
>>                                char **containerTTYPaths)
>>  {
>>      size_t i;
>> +    int ret = -1;
>> +    uid_t uid = (uid_t)-1;
>> +    gid_t gid = (gid_t)-1;
>> +    char *ttyHostPath = NULL;
>> +
>> +    if (ctrl->def->idmap.uidmap) {
>> +        uid = ctrl->def->idmap.uidmap[0].target;
>> +        gid = ctrl->def->idmap.gidmap[0].target;
>> +    }
>>  
>>      for (i = 0; i < ctrl->nconsoles; i++) {
>>          VIR_DEBUG("Opening tty on private %s", ctrl->devptmx);
>> -        if (lxcCreateTty(ctrl->devptmx,
>> +        if (lxcCreateTty(ctrl,
>>                           &ctrl->consoles[i].contFd,
>> -                         &containerTTYPaths[i]) < 0) {
>> +                         &containerTTYPaths[i], &ttyHostPath) < 0) {
>>              virReportSystemError(errno, "%s",
>>                                       _("Failed to allocate tty"));
>> -            return -1;
>> +            goto out;
>>          }
>> +
>> +        /* Change the owner of tty device to the root user of
>> container */
>> +        if (chown(ttyHostPath, uid, gid) < 0) {
>> +            virReportSystemError(errno,
>> +                                 _("Failed to change owner of tty"
>> +                                 " %s to %u:%u"),
>> +                                 ttyHostPath, uid, gid);
>> +            goto out;
>> +        }
>> +        VIR_FREE(ttyHostPath);
> 
> Why do you free ttyHostPath here?
> You already do it in the exit path.
> 

It has a cycle here,
we need free the ttyHostPath since we allocate it in lxcCreateTty every cycle.

>>      }
>> -    return 0;
>> +
>> +    ret = 0;
>> +out:
>> +    VIR_FREE(ttyHostPath);
> 
> Double free?
> 

Don't worry about it, VIR_FREE does some extra jobs for us. ;)

>> +    return ret;
>>  }
> 
> Thanks,
> //richard
> 



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