Re: [Qemu-devel] [V6 PATCH 6/9] virtio-9p: Create support in chroot environment

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

On 2/28/2011 3:22 AM, M. Mohan Kumar wrote:
> Add both chroot deamon & qemu side interfaces to create regular files in
> chroot environment
> 
> Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
> ---
>  hw/9pfs/virtio-9p-chroot-dm.c |   39 +++++++++++++++++++++++++++++++++++++++
>  hw/9pfs/virtio-9p-local.c     |   21 +++++++++++++++++++--
>  2 files changed, 58 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/9pfs/virtio-9p-chroot-dm.c b/hw/9pfs/virtio-9p-chroot-dm.c
> index c1d8c6e..985d42b 100644
> --- a/hw/9pfs/virtio-9p-chroot-dm.c
> +++ b/hw/9pfs/virtio-9p-chroot-dm.c
> @@ -83,6 +83,42 @@ static void chroot_do_open(V9fsFileObjectRequest *request, FdInfo *fd_info)
>      }
>  }
> 
> +/*
> + * Helper routine to create a file and return the file descriptor and
> + * error status in FdInfo structure.
> + */
> +static void chroot_do_create(V9fsFileObjectRequest *request, FdInfo *fd_info)
> +{
> +    uid_t cur_uid;
> +    gid_t cur_gid;
> +
> +    cur_uid = geteuid();
> +    cur_gid = getegid();
> +
> +    fd_info->fi_fd = -1;
> +
> +    if (setfsuid(request->data.uid) < 0) {
> +        fd_info->fi_fd = -errno;
> +        fd_info->fi_flags = FI_FD_INVALID;
> +        return;
> +    }
> +    if (setfsgid(request->data.gid) < 0) {
> +        fd_info->fi_fd = -errno;
> +        fd_info->fi_flags = FI_FD_INVALID;
> +        goto unset_uid;
> +    }
> +
> +    fd_info->fi_fd = open(request->path.path, request->data.flags,
> +                        request->data.mode);
> +    if (fd_info->fi_fd < 0) {
> +        fd_info->fi_fd = -errno;
> +        fd_info->fi_flags = FI_FD_INVALID;
> +    }
> +    setfsgid(cur_gid);
> +unset_uid:
> +    setfsuid(cur_uid);
> +}
> +
>  static int chroot_daemonize(int chroot_sock)
>  {
>      sigset_t sigset;
> @@ -177,6 +213,9 @@ int v9fs_chroot(FsContext *fs_ctx)
>          case T_OPEN:
>              chroot_do_open(&request, &fd_info);
>              break;
> +        case T_CREATE:
> +            chroot_do_create(&request, &fd_info);
> +            break;
>          default:
>              fd_info.fi_flags = FI_FD_SOCKERR;
>              break;
> diff --git a/hw/9pfs/virtio-9p-local.c b/hw/9pfs/virtio-9p-local.c
> index 0c55d35..3fed16c 100644
> --- a/hw/9pfs/virtio-9p-local.c
> +++ b/hw/9pfs/virtio-9p-local.c
> @@ -58,6 +58,22 @@ static int passthrough_open(FsContext *fs_ctx, const char *path, int flags)
>      return fd;
>  }
> 
> +static int passthrough_create(FsContext *fs_ctx, const char *path, int flags,
> +                    FsCred *credp)
> +{
> +    V9fsFileObjectRequest request;
> +    int fd;
> +
> +    fd = fill_fileobjectrequest(&request, path, credp);
> +    if (fd < 0) {
> +        return fd;

Here fd is -errno;
Need to assign it back to errno before returning.
You took care of it in passthrough_open() but not here.
Please check other places where this logic applies.

- JV

> +    }
> +    request.data.flags = flags;
> +    request.data.type = T_CREATE;
> +    fd = v9fs_request(fs_ctx, &request);
> +    return fd;
> +}
> +
>  static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
>  {
>      int err;
> @@ -382,8 +398,7 @@ static int local_open2(FsContext *fs_ctx, const char *path, int flags,
>              serrno = errno;
>              goto err_end;
>          }
> -    } else if ((fs_ctx->fs_sm == SM_PASSTHROUGH) ||
> -               (fs_ctx->fs_sm == SM_NONE)) {
> +    } else if (fs_ctx->fs_sm == SM_NONE) {
>          fd = open(rpath(fs_ctx, path), flags, credp->fc_mode);
>          if (fd == -1) {
>              return fd;
> @@ -393,6 +408,8 @@ static int local_open2(FsContext *fs_ctx, const char *path, int flags,
>              serrno = errno;
>              goto err_end;
>          }
> +    } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
> +        fd = passthrough_create(fs_ctx, path, flags, credp);
>      }
>      return fd;
>