Patchwork [V3] virtio-9p: Add Read only support for 9p export.

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Submitter Mohan Kumar M
Date May 24, 2011, 12:21 p.m.
Message ID <1306239693-6606-1-git-send-email-mohan@in.ibm.com>
Download mbox | patch
Permalink /patch/97156/
State New
Headers show

Comments

Mohan Kumar M - May 24, 2011, 12:21 p.m.
A new fsdev parameter "readonly" is introduced to control accessing 9p export.
readonly=on|off can be used to specify the access type. By default rw access
is given to 9p export.

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
---
Change from previous version V2:
* QEMU_OPT_BOOL is used for readdonly parameter

Changes from previous version:
* Use "readonly" option instead of "access"
* Change function return type to boolean where its needed

 fsdev/file-op-9p.h         |    1 +
 fsdev/qemu-fsdev.c         |   11 ++++++++++-
 fsdev/qemu-fsdev.h         |    3 +++
 hw/9pfs/virtio-9p-device.c |    5 +++++
 hw/9pfs/virtio-9p.c        |   41 +++++++++++++++++++++++++++++++++++++++++
 qemu-config.c              |    7 +++++++
 vl.c                       |    1 +
 7 files changed, 68 insertions(+), 1 deletions(-)
Stefan Hajnoczi - May 24, 2011, 12:31 p.m.
On Tue, May 24, 2011 at 1:21 PM, M. Mohan Kumar <mohan@in.ibm.com> wrote:
> A new fsdev parameter "readonly" is introduced to control accessing 9p export.
> readonly=on|off can be used to specify the access type. By default rw access
> is given to 9p export.
>
> Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
> ---
> Change from previous version V2:
> * QEMU_OPT_BOOL is used for readdonly parameter
>
> Changes from previous version:
> * Use "readonly" option instead of "access"
> * Change function return type to boolean where its needed
>
>  fsdev/file-op-9p.h         |    1 +
>  fsdev/qemu-fsdev.c         |   11 ++++++++++-
>  fsdev/qemu-fsdev.h         |    3 +++
>  hw/9pfs/virtio-9p-device.c |    5 +++++
>  hw/9pfs/virtio-9p.c        |   41 +++++++++++++++++++++++++++++++++++++++++
>  qemu-config.c              |    7 +++++++
>  vl.c                       |    1 +
>  7 files changed, 68 insertions(+), 1 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Patch

diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
index af9daf7..b1642eb 100644
--- a/fsdev/file-op-9p.h
+++ b/fsdev/file-op-9p.h
@@ -55,6 +55,7 @@  typedef struct FsContext
     SecModel fs_sm;
     uid_t uid;
     struct xattr_operations **xops;
+    int flags;
 } FsContext;
 
 void cred_init(FsCred *);
diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c
index 0b33290..2be732f 100644
--- a/fsdev/qemu-fsdev.c
+++ b/fsdev/qemu-fsdev.c
@@ -28,11 +28,12 @@  static FsTypeTable FsTypes[] = {
 int qemu_fsdev_add(QemuOpts *opts)
 {
     struct FsTypeListEntry *fsle;
-    int i;
+    int i, flags;
     const char *fsdev_id = qemu_opts_id(opts);
     const char *fstype = qemu_opt_get(opts, "fstype");
     const char *path = qemu_opt_get(opts, "path");
     const char *sec_model = qemu_opt_get(opts, "security_model");
+    int readonly = qemu_opt_get_bool(opts, "readonly", 0);
 
     if (!fsdev_id) {
         fprintf(stderr, "fsdev: No id specified\n");
@@ -65,12 +66,20 @@  int qemu_fsdev_add(QemuOpts *opts)
         return -1;
     }
 
+    flags = 0;
+    if (readonly) {
+        flags |= MS_RDONLY;
+    } else {
+        flags &= ~MS_RDONLY;
+    }
+
     fsle = qemu_malloc(sizeof(*fsle));
 
     fsle->fse.fsdev_id = qemu_strdup(fsdev_id);
     fsle->fse.path = qemu_strdup(path);
     fsle->fse.security_model = qemu_strdup(sec_model);
     fsle->fse.ops = FsTypes[i].ops;
+    fsle->fse.flags = flags;
 
     QTAILQ_INSERT_TAIL(&fstype_entries, fsle, next);
     return 0;
diff --git a/fsdev/qemu-fsdev.h b/fsdev/qemu-fsdev.h
index f9f08d3..4c66ce6 100644
--- a/fsdev/qemu-fsdev.h
+++ b/fsdev/qemu-fsdev.h
@@ -42,6 +42,7 @@  typedef struct FsTypeEntry {
     char *path;
     char *security_model;
     FileOperations *ops;
+    int flags;
 } FsTypeEntry;
 
 typedef struct FsTypeListEntry {
@@ -52,4 +53,6 @@  typedef struct FsTypeListEntry {
 int qemu_fsdev_add(QemuOpts *opts);
 FsTypeEntry *get_fsdev_fsentry(char *id);
 extern FileOperations local_ops;
+
+#define MS_RDONLY   0x01
 #endif
diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index f985486..4de32e4 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -107,6 +107,11 @@  VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
         s->ctx.xops = none_xattr_ops;
     }
 
+    s->ctx.flags = 0;
+    if (fse->flags & MS_RDONLY) {
+        s->ctx.flags |= MS_RDONLY;
+    }
+
     if (lstat(fse->path, &stat)) {
         fprintf(stderr, "share path %s does not exist\n", fse->path);
         exit(1);
diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index 21865b1..ceb4034 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -1192,6 +1192,11 @@  static void v9fs_fix_path(V9fsString *dst, V9fsString *src, int len)
     v9fs_string_free(&str);
 }
 
+static inline bool is_ro_export(FsContext *fs_ctx)
+{
+    return fs_ctx->flags & MS_RDONLY;
+}
+
 static void v9fs_version(V9fsState *s, V9fsPDU *pdu)
 {
     V9fsString version;
@@ -1734,6 +1739,11 @@  static void v9fs_open_post_lstat(V9fsState *s, V9fsOpenState *vs, int err)
         vs->fidp->fs.dir = v9fs_do_opendir(s, &vs->fidp->path);
         v9fs_open_post_opendir(s, vs, err);
     } else {
+        if (is_ro_export(&s->ctx) &&
+            (vs->mode & O_WRONLY || vs->mode & O_RDWR || vs->mode & O_APPEND)) {
+                err = -EROFS;
+                goto out;
+        }
         if (s->proto_version == V9FS_PROTO_2000L) {
             flags = vs->mode;
             flags &= ~(O_NOCTTY | O_ASYNC | O_CREAT);
@@ -3606,6 +3616,33 @@  static pdu_handler_t *pdu_handlers[] = {
     [P9_TREMOVE] = v9fs_remove,
 };
 
+static inline bool is_read_only_op(int id)
+{
+    switch (id) {
+    case P9_TREADDIR:
+    case P9_TSTATFS:
+    case P9_TGETATTR:
+    case P9_TXATTRWALK:
+    case P9_TLOCK:
+    case P9_TGETLOCK:
+    case P9_TREADLINK:
+    case P9_TVERSION:
+    case P9_TLOPEN:
+    case P9_TATTACH:
+    case P9_TSTAT:
+    case P9_TWALK:
+    case P9_TCLUNK:
+    case P9_TFSYNC:
+    case P9_TOPEN:
+    case P9_TREAD:
+    case P9_TAUTH:
+    case P9_TFLUSH:
+        return 1;
+    default:
+        return 0;
+    }
+}
+
 static void submit_pdu(V9fsState *s, V9fsPDU *pdu)
 {
     pdu_handler_t *handler;
@@ -3619,6 +3656,10 @@  static void submit_pdu(V9fsState *s, V9fsPDU *pdu)
     handler = pdu_handlers[pdu->id];
     BUG_ON(handler == NULL);
 
+    if (is_ro_export(&s->ctx) && !is_read_only_op(pdu->id)) {
+        complete_pdu(s, pdu, -EROFS);
+        return;
+    }
     handler(s, pdu);
 }
 
diff --git a/qemu-config.c b/qemu-config.c
index 14d3419..25a413b 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -170,7 +170,11 @@  QemuOptsList qemu_fsdev_opts = {
         }, {
             .name = "security_model",
             .type = QEMU_OPT_STRING,
+        }, {
+            .name = "readonly",
+            .type = QEMU_OPT_BOOL,
         },
+
         { /*End of list */ }
     },
 };
@@ -192,6 +196,9 @@  QemuOptsList qemu_virtfs_opts = {
         }, {
             .name = "security_model",
             .type = QEMU_OPT_STRING,
+        }, {
+            .name = "readonly",
+            .type = QEMU_OPT_BOOL,
         },
 
         { /*End of list */ }
diff --git a/vl.c b/vl.c
index 6b9a2f6..70be0d1 100644
--- a/vl.c
+++ b/vl.c
@@ -2483,6 +2483,7 @@  int main(int argc, char **argv, char **envp)
                 qemu_opt_set(fsdev, "security_model",
                              qemu_opt_get(opts, "security_model"));
 
+                qemu_opt_set(fsdev, "readonly", qemu_opt_get(opts, "readonly"));
                 device = qemu_opts_create(qemu_find_opts("device"), NULL, 0);
                 qemu_opt_set(device, "driver", "virtio-9p-pci");
                 qemu_opt_set(device, "fsdev",