fs: dlm: add debugfs rawmsg send functionality

This patch adds a dlm functionality to send a raw dlm message to a
specific cluster node. This raw message can be build by user space and
send out by writing the message to "rawmsg" dlm debugfs file.

There is a in progress scapy dlm module which provides a easy build of
DLM messages in user space. For example:

DLM(h_cmd=3, o_nextcmd=1, h_nodeid=1, h_lockspace=0xe4f48a18, ...)

The goal is to provide an easy reproducable state to crash DLM or to
fuzz the DLM kernel stack if there are possible ways to crash it.

Note: that if the sequence number is zero and dlm version is not set to
3.1 the kernel will automatic will set a right sequence number, otherwise
DLM stack testing is not possible.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index 47e9d57..555904e 100644 (file)
--- a/fs/dlm/debug_fs.c
+++ b/fs/dlm/debug_fs.c
@@ -768,6 +768,42 @@ static int dlm_version_show(struct seq_file *file, void *offset)
 }
 DEFINE_SHOW_ATTRIBUTE(dlm_version);
 
+static ssize_t dlm_rawmsg_write(struct file *fp, const char __user *user_buf,
+                               size_t count, loff_t *ppos)
+{
+       void *buf;
+       int ret;
+
+       if (count > PAGE_SIZE || count < sizeof(struct dlm_header))
+               return -EINVAL;
+
+       buf = kmalloc(PAGE_SIZE, GFP_NOFS);
+       if (!buf)
+               return -ENOMEM;
+
+       if (copy_from_user(buf, user_buf, count)) {
+               ret = -EFAULT;
+               goto out;
+       }
+
+       ret = dlm_midcomms_rawmsg_send(fp->private_data, buf, count);
+       if (ret)
+               goto out;
+
+       kfree(buf);
+       return count;
+
+out:
+       kfree(buf);
+       return ret;
+}
+
+static const struct file_operations dlm_rawmsg_fops = {
+       .open   = simple_open,
+       .write  = dlm_rawmsg_write,
+       .llseek = no_llseek,
+};
+
 void *dlm_create_debug_comms_file(int nodeid, void *data)
 {
        struct dentry *d_node;
@@ -782,6 +818,7 @@ void *dlm_create_debug_comms_file(int nodeid, void *data)
        debugfs_create_file("send_queue_count", 0444, d_node, data,
                            &dlm_send_queue_cnt_fops);
        debugfs_create_file("version", 0444, d_node, data, &dlm_version_fops);
+       debugfs_create_file("rawmsg", 0200, d_node, data, &dlm_rawmsg_fops);
 
        return d_node;
 }

diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index 95a5643..0b9bce6 100644 (file)
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -1427,3 +1427,51 @@ int dlm_midcomms_close(int nodeid)
 
        return ret;
 }
+
+/* debug functionality to send raw dlm msg from user space */
+struct dlm_rawmsg_data {
+       struct midcomms_node *node;
+       void *buf;
+};
+
+static void midcomms_new_rawmsg_cb(void *data)
+{
+       struct dlm_rawmsg_data *rd = data;
+       struct dlm_header *h = rd->buf;
+
+       switch (h->h_version) {
+       case cpu_to_le32(DLM_VERSION_3_1):
+               break;
+       default:
+               switch (h->h_cmd) {
+               case DLM_OPTS:
+                       if (!h->u.h_seq)
+                               h->u.h_seq = rd->node->seq_send++;
+                       break;
+               default:
+                       break;
+               }
+               break;
+       }
+}
+
+int dlm_midcomms_rawmsg_send(struct midcomms_node *node, void *buf,
+                            int buflen)
+{
+       struct dlm_rawmsg_data rd;
+       struct dlm_msg *msg;
+       char *msgbuf;
+
+       rd.node = node;
+       rd.buf = buf;
+
+       msg = dlm_lowcomms_new_msg(node->nodeid, buflen, GFP_NOFS,
+                                  &msgbuf, midcomms_new_rawmsg_cb, &rd);
+       if (!msg)
+               return -ENOMEM;
+
+       memcpy(msgbuf, buf, buflen);
+       dlm_lowcomms_commit_msg(msg);
+       return 0;
+}
+

diff --git a/fs/dlm/midcomms.h b/fs/dlm/midcomms.h
index 579abc6..bc63cf7 100644 (file)
--- a/fs/dlm/midcomms.h
+++ b/fs/dlm/midcomms.h
@@ -28,6 +28,8 @@ const char *dlm_midcomms_state(struct midcomms_node *node);
 unsigned long dlm_midcomms_flags(struct midcomms_node *node);
 int dlm_midcomms_send_queue_cnt(struct midcomms_node *node);
 uint32_t dlm_midcomms_version(struct midcomms_node *node);
+int dlm_midcomms_rawmsg_send(struct midcomms_node *node, void *buf,
+                            int buflen);
 
 #endif                         /* __MIDCOMMS_DOT_H__ */