9p: Properly check/translate flags in unlinkat

The 9p-local code previously relied on P9_DOTL_AT_REMOVEDIR and AT_REMOVEDIR
having the same numerical value and deferred any errorchecking to the
syscall itself. However, while the former assumption is true on Linux,
it is not true in general. 9p-handle did this properly however. Move
the translation code to the generic 9p server code and add an error
if unrecognized flags are passed.

Signed-off-by: Keno Fischer <keno@juliacomputing.com>
Signed-off-by: Greg Kurz <groug@kaod.org>

2 files changed, 12 insertions, 9 deletions

diff --git a/hw/9pfs/9p-handle.c b/hw/9pfs/9p-handle.c
index 4dc0d2bed1..f3641dbe4a 100644
--- a/hw/9pfs/9p-handle.c
+++ b/hw/9pfs/9p-handle.c
@@ -559,19 +559,13 @@ static int handle_unlinkat(FsContext *ctx, V9fsPath *dir,
 {
     int dirfd, ret;
     HandleData *data = (HandleData *) ctx->private;
-    int rflags;
 
     dirfd = open_by_handle(data->mountfd, dir->data, O_PATH);
     if (dirfd < 0) {
         return dirfd;
     }
 
-    rflags = 0;
-    if (flags & P9_DOTL_AT_REMOVEDIR) {
-        rflags |= AT_REMOVEDIR;
-    }
-
-    ret = unlinkat(dirfd, name, rflags);
+    ret = unlinkat(dirfd, name, flags);
 
     close(dirfd);
     return ret;
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index 4386d69817..c842ec555e 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -2522,7 +2522,7 @@ static void coroutine_fn v9fs_unlinkat(void *opaque)
 {
     int err = 0;
     V9fsString name;
-    int32_t dfid, flags;
+    int32_t dfid, flags, rflags = 0;
     size_t offset = 7;
     V9fsPath path;
     V9fsFidState *dfidp;
@@ -2549,6 +2549,15 @@ static void coroutine_fn v9fs_unlinkat(void *opaque)
         goto out_nofid;
     }
 
+    if (flags & ~P9_DOTL_AT_REMOVEDIR) {
+        err = -EINVAL;
+        goto out_nofid;
+    }
+
+    if (flags & P9_DOTL_AT_REMOVEDIR) {
+        rflags |= AT_REMOVEDIR;
+    }
+
     dfidp = get_fid(pdu, dfid);
     if (dfidp == NULL) {
         err = -EINVAL;
@@ -2567,7 +2576,7 @@ static void coroutine_fn v9fs_unlinkat(void *opaque)
     if (err < 0) {
         goto out_err;
     }
-    err = v9fs_co_unlinkat(pdu, &dfidp->path, &name, flags);
+    err = v9fs_co_unlinkat(pdu, &dfidp->path, &name, rflags);
     if (!err) {
         err = offset;
     }