Re: [Qemu-devel] [PATCH -V4 1/7] virtio-9p: Introduces an option to specify the security model.

["Venkateswararao Jujjuri (JV)" <jvrao@linux.vnet.ibm.com>]

Aneesh Kumar K.V wrote:
> On Wed, May 26, 2010 at 04:21:40PM -0700, Venkateswararao Jujjuri (JV) wrote:
>> The new option is:
>>
>> -fsdev fstype,id=myid,path=/share_path/,security_model=[mapped|passthrough]
>> -virtfs fstype,path=/share_path/,security_model=[mapped|passthrough],mnt_tag=tag
>>
>> In the case of mapped security model, files are created with QEMU user
>> credentials and the client-user's credentials are saved in extended attributes.
>> Whereas in the case of passthrough security model, files on the
>> filesystem are directly created with client-user's credentials.
>>
>> Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
>> ---
>>  fsdev/qemu-fsdev.c |   14 +++++++++++++-
>>  fsdev/qemu-fsdev.h |    1 +
>>  hw/virtio-9p.c     |   22 ++++++++++++++++++----
>>  qemu-config.c      |   12 +++++++++---
>>  qemu-options.hx    |   15 +++++++++++----
>>  vl.c               |   18 +++++++++++++++---
>>  6 files changed, 67 insertions(+), 15 deletions(-)
>>
>> diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c
>> index 813e1f7..7d7a153 100644
>> --- a/fsdev/qemu-fsdev.c
>> +++ b/fsdev/qemu-fsdev.c
>> @@ -34,7 +34,7 @@ int qemu_fsdev_add(QemuOpts *opts)
>>          return -1;
>>      }
>>  
>> -     for (i = 0; i < ARRAY_SIZE(FsTypes); i++) {
>> +    for (i = 0; i < ARRAY_SIZE(FsTypes); i++) {
>>          if (strcmp(FsTypes[i].name, qemu_opt_get(opts, "fstype")) == 0) {
>>              break;
>>          }
> 
> 
> Don't do whitespace fixup in the same patch.

Ok. 

> 
> 
>> @@ -46,10 +46,22 @@ int qemu_fsdev_add(QemuOpts *opts)
>>          return -1;
>>      }
>>  
>> +    if (qemu_opt_get(opts, "path") == NULL) {
>> +        fprintf(stderr, "fsdev: No path specified.\n");
>> +        return -1;
>> +    }
>> +
> 
> 
> How is this related to new option ? 

Not related. Will send out another patch.

> 
> 
>> +    if (qemu_opt_get(opts, "security_model") == NULL) {
>> +        fprintf(stderr, "fsdev: No security_model specified.\n");
>> +        return -1;
>> +    }
>> +
>>      fsle = qemu_malloc(sizeof(*fsle));
>>  
>>      fsle->fse.fsdev_id = qemu_strdup(qemu_opts_id(opts));
>>      fsle->fse.path = qemu_strdup(qemu_opt_get(opts, "path"));
>> +    fsle->fse.security_model = qemu_strdup(qemu_opt_get(opts,
>> +                "security_model"));
>>      fsle->fse.ops = FsTypes[i].ops;
>>  
>>      QTAILQ_INSERT_TAIL(&fstype_entries, fsle, next);
>> diff --git a/fsdev/qemu-fsdev.h b/fsdev/qemu-fsdev.h
>> index b50fbe0..6c27881 100644
>> --- a/fsdev/qemu-fsdev.h
>> +++ b/fsdev/qemu-fsdev.h
>> @@ -40,6 +40,7 @@ typedef struct FsTypeTable {
>>  typedef struct FsTypeEntry {
>>      char *fsdev_id;
>>      char *path;
>> +    char *security_model;
>>      FileOperations *ops;
>>  } FsTypeEntry;
>>  
>> diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
>> index 687abc0..a57562a 100644
>> --- a/hw/virtio-9p.c
>> +++ b/hw/virtio-9p.c
>> @@ -2402,7 +2402,7 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
>>          /* We don't have a fsdev identified by fsdev_id */
>>          fprintf(stderr, "Virtio-9p device couldn't find fsdev "
>>                      "with the id %s\n", conf->fsdev_id);
>> -        exit(1);
>> +        return NULL;
>>      }
>>  
>>      if (!fse->path || !conf->tag) {
>> @@ -2410,15 +2410,29 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
>>          fprintf(stderr, "fsdev with id %s needs path "
>>                  "and Virtio-9p device needs mount_tag arguments\n",
>>                  conf->fsdev_id);
>> -        exit(1);
>> +        return NULL;
>> +    }
>> +
>> +    if (!strcmp(fse->security_model, "passthrough")) {
>> +        /* Files on the Fileserver set to client user credentials */
>> +    } else if (!strcmp(fse->security_model, "mapped")) {
>> +        /* Files on the fileserver are set to QEMU credentials.
>> +         * Client user credentials are saved in extended attributes.
>> +         */
> 
> 
> The above two if should be dropped add them when you have something to do in the if () { }
> section.
> 
> 
>> +    } else {
>> +        /* user haven't specified a correct security option */
>> +        fprintf(stderr, "one of the following must be specified as the"
>> +                "security option:\n\t security_model=passthrough \n\t "
>> +                "security_model=mapped\n");
>> +        return NULL;
>>      }
> 
> We should only have this

Well, it is tricky. Given that we should not fix/change the code in the previous patches
in the same series, code becomes ugly without the above place holders.

Given that I can't change this part of the code in my next patch in the series.. I need to go like this:

if ( !strcmp(fse->security_model, "passthrough") && !strcmp(fse->security_model, "mapped"))
{
    Error;
    Return NULL;
}

Then in the next patch, 
Below this i need to add in the next patch.
if (!strcmp(fse->security_model, "passthrough"))
 blah
if (!strcmp(fse->security_model, "mapped"))
  blah

Which makes the code to check do two srrncmps for each model.

Hence If there is no major objection.. I would like to keep it this way.

Thanks,
JV

> 
> 
> 
>>  
>>      if (lstat(fse->path, &stat)) {
>>          fprintf(stderr, "share path %s does not exist\n", fse->path);
>> -        exit(1);
>> +        return NULL;
>>      } else if (!S_ISDIR(stat.st_mode)) {
>>          fprintf(stderr, "share path %s is not a directory \n", fse->path);
>> -        exit(1);
>> +        return NULL;
>>      }
>>  
>>      s->ctx.fs_root = qemu_strdup(fse->path);
>> diff --git a/qemu-config.c b/qemu-config.c
>> index d500885..e1e3aa1 100644
>> --- a/qemu-config.c
>> +++ b/qemu-config.c
>> @@ -160,9 +160,12 @@ QemuOptsList qemu_fsdev_opts = {
>>          {
>>              .name = "fstype",
>>              .type = QEMU_OPT_STRING,
>> -        }, {
>> +        },{
>>              .name = "path",
>>              .type = QEMU_OPT_STRING,
>> +        },{
>> +            .name = "security_model",
>> +            .type = QEMU_OPT_STRING,
>>          },
>>          { /*End of list */ }
>>      },
>> @@ -178,12 +181,15 @@ QemuOptsList qemu_virtfs_opts = {
>>          {
>>              .name = "fstype",
>>              .type = QEMU_OPT_STRING,
>> -        }, {
>> +        },{
>>              .name = "path",
>>              .type = QEMU_OPT_STRING,
>> -        }, {
>> +        },{
>>              .name = "mount_tag",
>>              .type = QEMU_OPT_STRING,
>> +        },{
>> +            .name = "security_model",
>> +            .type = QEMU_OPT_STRING,
>>          },
>>  
>>          { /*End of list */ }
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index 12f6b51..d557c92 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -482,7 +482,7 @@ ETEXI
>>  DEFHEADING(File system options:)
>>  
>>  DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
>> -    "-fsdev local,id=id,path=path\n",
>> +    "-fsdev local,id=id,path=path,security_model=[mapped|passthrough]\n",
>>      QEMU_ARCH_ALL)
>>  
>>  STEXI
>> @@ -498,7 +498,7 @@ The specific Fstype will determine the applicable options.
>>  
>>  Options to each backend are described below.
>>  
>> -@item -fsdev local ,id=@var{id} ,path=@var{path}
>> +@item -fsdev local ,id=@var{id} ,path=@var{path} ,security_model=@var{security_model}
>>  
>>  Create a file-system-"device" for local-filesystem.
>>  
>> @@ -506,6 +506,9 @@ Create a file-system-"device" for local-filesystem.
>>  
>>  @option{path} specifies the path to be exported. @option{path} is required.
>>  
>> +@option{security_model} specifies the security model to be followed.
>> +@option{security_model} is required.
>> +
>>  @end table
>>  ETEXI
>>  #endif
>> @@ -514,7 +517,7 @@ ETEXI
>>  DEFHEADING(Virtual File system pass-through options:)
>>  
>>  DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
>> -    "-virtfs local,path=path,mount_tag=tag\n",
>> +    "-virtfs local,path=path,mount_tag=tag,security_model=[mapped|passthrough]\n",
>>      QEMU_ARCH_ALL)
>>  
>>  STEXI
>> @@ -530,7 +533,7 @@ The specific Fstype will determine the applicable options.
>>  
>>  Options to each backend are described below.
>>  
>> -@item -virtfs local ,path=@var{path} ,mount_tag=@var{mount_tag}
>> +@item -virtfs local ,path=@var{path} ,mount_tag=@var{mount_tag} ,security_model=@var{security_model}
>>  
>>  Create a Virtual file-system-pass through for local-filesystem.
>>  
>> @@ -538,6 +541,10 @@ Create a Virtual file-system-pass through for local-filesystem.
>>  
>>  @option{path} specifies the path to be exported. @option{path} is required.
>>  
>> +@option{security_model} specifies the security model to be followed.
>> +@option{security_model} is required.
>> +
>> +
>>  @option{mount_tag} specifies the tag with which the exported file is mounted.
>>  @option{mount_tag} is required.
>>  
>> diff --git a/vl.c b/vl.c
>> index 85bcc84..a341781 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -3109,10 +3109,21 @@ int main(int argc, char **argv, char **envp)
>>                      exit(1);
>>                  }
>>  
>> -                len = strlen(",id=,path=");
>> +                if (qemu_opt_get(opts, "fstype") == NULL ||
>> +                        qemu_opt_get(opts, "mount_tag") == NULL ||
>> +                        qemu_opt_get(opts, "path") == NULL ||
>> +                        qemu_opt_get(opts, "security_model") == NULL) {
>> +                    fprintf(stderr, "Usage: -virtfs fstype,path=/share_path/,"
>> +                            "security_model=[mapped|passthrough],"
>> +                            "mnt_tag=tag.\n");
>> +                    exit(1);
>> +                }
>> +
>> +                len = strlen(",id=,path=,security_model=");
>>                  len += strlen(qemu_opt_get(opts, "fstype"));
>>                  len += strlen(qemu_opt_get(opts, "mount_tag"));
>>                  len += strlen(qemu_opt_get(opts, "path"));
>> +                len += strlen(qemu_opt_get(opts, "security_model"));
>>                  arg_fsdev = qemu_malloc((len + 1) * sizeof(*arg_fsdev));
>>  
>>                  if (!arg_fsdev) {
>> @@ -3121,10 +3132,11 @@ int main(int argc, char **argv, char **envp)
>>                      exit(1);
>>                  }
>>  
>> -                sprintf(arg_fsdev, "%s,id=%s,path=%s",
>> +                sprintf(arg_fsdev, "%s,id=%s,path=%s,security_model=%s",
>>                                  qemu_opt_get(opts, "fstype"),
>>                                  qemu_opt_get(opts, "mount_tag"),
>> -                                qemu_opt_get(opts, "path"));
>> +                                qemu_opt_get(opts, "path"),
>> +                                qemu_opt_get(opts, "security_model"));
>>  
>>                  len = strlen("virtio-9p-pci,fsdev=,mount_tag=");
>>                  len += 2*strlen(qemu_opt_get(opts, "mount_tag"));
>> -- 
>> 1.6.5.2
>>
>>