[Qemu-devel] [PATCH -V4 4/7] virtio-9p: Implement Security model for mknod related files

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

In the mapped security model all the special files are created as regular files
on the fileserver and appropriate mode bits are added to the extended
attributes. These extended attributes are used to present this file
as special file to the client.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
---
 hw/file-op-9p.h      |    3 +-
 hw/virtio-9p-local.c |   58 +++++++++++++++++++++++++++++--------------------
 hw/virtio-9p.c       |   39 ++++++++++-----------------------
 3 files changed, 47 insertions(+), 53 deletions(-)

diff --git a/hw/file-op-9p.h b/hw/file-op-9p.h
index 73d59b2..144dd77 100644
--- a/hw/file-op-9p.h
+++ b/hw/file-op-9p.h
@@ -51,8 +51,7 @@ typedef struct FileOperations
     ssize_t (*readlink)(FsContext *, const char *, char *, size_t);
     int (*chmod)(FsContext *, const char *, mode_t);
     int (*chown)(FsContext *, const char *, uid_t, gid_t);
-    int (*mknod)(FsContext *, const char *, mode_t, dev_t);
-    int (*mksock)(FsContext *, const char *);
+    int (*mknod)(FsContext *, const char *, FsCred *);
     int (*utime)(FsContext *, const char *, const struct utimbuf *);
     int (*remove)(FsContext *, const char *);
     int (*symlink)(FsContext *, const char *, const char *);
diff --git a/hw/virtio-9p-local.c b/hw/virtio-9p-local.c
index f6c2fe2..bd8c1c7 100644
--- a/hw/virtio-9p-local.c
+++ b/hw/virtio-9p-local.c
@@ -134,33 +134,44 @@ static int local_chmod(FsContext *ctx, const char *path, mode_t mode)
     return chmod(rpath(ctx, path), mode);
 }
 
-static int local_mknod(FsContext *ctx, const char *path, mode_t mode, dev_t dev)
+static int local_mknod(FsContext *fs_ctx, const char *path, FsCred *credp)
 {
-    return mknod(rpath(ctx, path), mode, dev);
-}
-
-static int local_mksock(FsContext *ctx2, const char *path)
-{
-    struct sockaddr_un addr;
-    int s;
-
-    addr.sun_family = AF_UNIX;
-    snprintf(addr.sun_path, 108, "%s", rpath(ctx2, path));
-
-    s = socket(PF_UNIX, SOCK_STREAM, 0);
-    if (s == -1) {
-        return -1;
-    }
-
-    if (bind(s, (struct sockaddr *)&addr, sizeof(addr))) {
-        close(s);
-        return -1;
+    int err = -1;
+    int serrno = 0;
+    /* Determine the security model */
+    if (fs_ctx->fs_sm == SM_MAPPED) {
+        err = mknod(rpath(fs_ctx, path), SM_LOCAL_MODE_BITS|S_IFREG, 0);
+        if (err == -1) {
+            return err;
+        }
+        local_set_xattr(rpath(fs_ctx, path), credp);
+        if (err == -1) {
+            serrno = errno;
+            goto err_end;
+        }
+    } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
+        err = mknod(rpath(fs_ctx, path), credp->fc_mode, credp->fc_rdev);
+        if (err == -1) {
+            return err;
+        }
+        err = chmod(rpath(fs_ctx, path), credp->fc_mode & 07777);
+        if (err == -1) {
+            serrno = errno;
+            goto err_end;
+        }
+        err = chown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid);
+        if (err == -1) {
+            serrno = errno;
+            goto err_end;
+        }
     }
+    return err;
 
-    close(s);
-    return 0;
+err_end:
+    remove(rpath(fs_ctx, path));
+    errno = serrno;
+    return err;
 }
-
 static int local_mkdir(FsContext *fs_ctx, const char *path, FsCred *credp)
 {
     int err = -1;
@@ -351,7 +362,6 @@ FileOperations local_ops = {
     .writev = local_writev,
     .chmod = local_chmod,
     .mknod = local_mknod,
-    .mksock = local_mksock,
     .mkdir = local_mkdir,
     .fstat = local_fstat,
     .open2 = local_open2,
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index ef870a3..38c1d68 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -157,14 +157,15 @@ static int v9fs_do_chmod(V9fsState *s, V9fsString *path, mode_t mode)
     return s->ops->chmod(&s->ctx, path->data, mode);
 }
 
-static int v9fs_do_mknod(V9fsState *s, V9fsString *path, mode_t mode, dev_t dev)
+static int v9fs_do_mknod(V9fsState *s, V9fsCreateState *vs, mode_t mode,
+        dev_t dev)
 {
-    return s->ops->mknod(&s->ctx, path->data, mode, dev);
-}
-
-static int v9fs_do_mksock(V9fsState *s, V9fsString *path)
-{
-    return s->ops->mksock(&s->ctx, path->data);
+    FsCred cred;
+    cred_init(&cred);
+    cred.fc_uid = vs->fidp->uid;
+    cred.fc_mode = mode;
+    cred.fc_rdev = dev;
+    return s->ops->mknod(&s->ctx, vs->fullname.data, &cred);
 }
 
 static int v9fs_do_mkdir(V9fsState *s, V9fsCreateState *vs)
@@ -1725,22 +1726,6 @@ out:
     v9fs_post_create(s, vs, err);
 }
 
-static void v9fs_create_post_mksock(V9fsState *s, V9fsCreateState *vs,
-                                                                int err)
-{
-    if (err) {
-        err = -errno;
-        goto out;
-    }
-
-    err = v9fs_do_chmod(s, &vs->fullname, vs->perm & 0777);
-    v9fs_create_post_perms(s, vs, err);
-    return;
-
-out:
-    v9fs_post_create(s, vs, err);
-}
-
 static void v9fs_create_post_fstat(V9fsState *s, V9fsCreateState *vs, int err)
 {
     if (err) {
@@ -1816,14 +1801,14 @@ static void v9fs_create_post_lstat(V9fsState *s, V9fsCreateState *vs, int err)
         }
 
         nmode |= vs->perm & 0777;
-        err = v9fs_do_mknod(s, &vs->fullname, nmode, makedev(major, minor));
+        err = v9fs_do_mknod(s, vs, nmode, makedev(major, minor));
         v9fs_create_post_perms(s, vs, err);
     } else if (vs->perm & P9_STAT_MODE_NAMED_PIPE) {
-        err = v9fs_do_mknod(s, &vs->fullname, S_IFIFO | (vs->mode & 0777), 0);
+        err = v9fs_do_mknod(s, vs, S_IFIFO | (vs->perm & 0777), 0);
         v9fs_post_create(s, vs, err);
     } else if (vs->perm & P9_STAT_MODE_SOCKET) {
-        err = v9fs_do_mksock(s, &vs->fullname);
-        v9fs_create_post_mksock(s, vs, err);
+        err = v9fs_do_mknod(s, vs, S_IFSOCK | (vs->perm & 0777), 0);
+        v9fs_post_create(s, vs, err);
     } else {
         vs->fidp->fd = v9fs_do_open2(s, vs);
         v9fs_create_post_open2(s, vs, err);
-- 
1.6.5.2