kclient: check size on llseek(..., SEEK_END)

diff --git a/src/kernel/file.c b/src/kernel/file.c
index 89e6398e7993d162726a464f9d13a742ae668d22..fb46d4ed361075d533c5768eea77f60f7d5aee0a 100644 (file)
--- a/src/kernel/file.c
+++ b/src/kernel/file.c
@@ -847,10 +847,60 @@ out:
        return ret;
 }
 
+/*
+ * llseek.  be sure to verify file size on SEEK_END.
+ */
+static loff_t ceph_llseek(struct file *file, loff_t offset, int origin)
+{
+       struct inode *inode = file->f_mapping->host;
+       int ret;
+
+       mutex_lock(&inode->i_mutex);
+       __ceph_do_pending_vmtruncate(inode);
+       switch (origin) {
+       case SEEK_END:
+               ret = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE);
+               if (ret < 0) {
+                       offset = ret;
+                       goto out;
+               }
+               offset += inode->i_size;
+               break;
+       case SEEK_CUR:
+               /*
+                * Here we special-case the lseek(fd, 0, SEEK_CUR)
+                * position-querying operation.  Avoid rewriting the "same"
+                * f_pos value back to the file because a concurrent read(),
+                * write() or lseek() might have altered it
+                */
+               if (offset == 0) {
+                       offset = file->f_pos;
+                       goto out;
+               }
+               offset += file->f_pos;
+               break;
+       }
+
+       if (offset < 0 || offset > inode->i_sb->s_maxbytes) {
+               offset = -EINVAL;
+               goto out;
+       }
+
+       /* Special lock needed here? */
+       if (offset != file->f_pos) {
+               file->f_pos = offset;
+               file->f_version = 0;
+       }
+
+out:
+       mutex_unlock(&inode->i_mutex);
+       return offset;
+}
+
 const struct file_operations ceph_file_fops = {
        .open = ceph_open,
        .release = ceph_release,
-       .llseek = generic_file_llseek,
+       .llseek = ceph_llseek,
        .read = do_sync_read,
        .write = do_sync_write,
        .aio_read = ceph_aio_read,