openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/net/hsr/hsr_debugfs.c b/net/hsr/hsr_debugfs.c
new file mode 100644
index 000000000..5b2cfac3b
--- /dev/null
+++ b/net/hsr/hsr_debugfs.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * debugfs code for HSR & PRP
+ * Copyright (C) 2019 Texas Instruments Incorporated
+ *
+ * Author(s):
+ *	Murali Karicheri <m-karicheri2@ti.com>
+ */
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/debugfs.h>
+#include "hsr_main.h"
+#include "hsr_framereg.h"
+
+static struct dentry *hsr_debugfs_root_dir;
+
+/* hsr_node_table_show - Formats and prints node_table entries */
+static int
+hsr_node_table_show(struct seq_file *sfp, void *data)
+{
+	struct hsr_priv *priv = (struct hsr_priv *)sfp->private;
+	struct hsr_node *node;
+
+	seq_printf(sfp, "Node Table entries for (%s) device\n",
+		   (priv->prot_version == PRP_V1 ? "PRP" : "HSR"));
+	seq_puts(sfp, "MAC-Address-A,    MAC-Address-B,    time_in[A], ");
+	seq_puts(sfp, "time_in[B], Address-B port, ");
+	if (priv->prot_version == PRP_V1)
+		seq_puts(sfp, "SAN-A, SAN-B, DAN-P\n");
+	else
+		seq_puts(sfp, "DAN-H\n");
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(node, &priv->node_db, mac_list) {
+		/* skip self node */
+		if (hsr_addr_is_self(priv, node->macaddress_A))
+			continue;
+		seq_printf(sfp, "%pM ", &node->macaddress_A[0]);
+		seq_printf(sfp, "%pM ", &node->macaddress_B[0]);
+		seq_printf(sfp, "%10lx, ", node->time_in[HSR_PT_SLAVE_A]);
+		seq_printf(sfp, "%10lx, ", node->time_in[HSR_PT_SLAVE_B]);
+		seq_printf(sfp, "%14x, ", node->addr_B_port);
+
+		if (priv->prot_version == PRP_V1)
+			seq_printf(sfp, "%5x, %5x, %5x\n",
+				   node->san_a, node->san_b,
+				   (node->san_a == 0 && node->san_b == 0));
+		else
+			seq_printf(sfp, "%5x\n", 1);
+	}
+	rcu_read_unlock();
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(hsr_node_table);
+
+void hsr_debugfs_rename(struct net_device *dev)
+{
+	struct hsr_priv *priv = netdev_priv(dev);
+	int err;
+
+	err = debugfs_change_name(priv->node_tbl_root, "%s", dev->name);
+	if (err)
+		netdev_warn(dev, "failed to rename\n");
+}
+
+/* hsr_debugfs_init - create hsr node_table file for dumping
+ * the node table
+ *
+ * Description:
+ * When debugfs is configured this routine sets up the node_table file per
+ * hsr device for dumping the node_table entries
+ */
+void hsr_debugfs_init(struct hsr_priv *priv, struct net_device *hsr_dev)
+{
+	struct dentry *de = NULL;
+
+	de = debugfs_create_dir(hsr_dev->name, hsr_debugfs_root_dir);
+	if (IS_ERR(de)) {
+		pr_err("Cannot create hsr debugfs directory\n");
+		return;
+	}
+
+	priv->node_tbl_root = de;
+
+	de = debugfs_create_file("node_table", S_IFREG | 0444,
+				 priv->node_tbl_root, priv,
+				 &hsr_node_table_fops);
+	if (IS_ERR(de)) {
+		pr_err("Cannot create hsr node_table file\n");
+		debugfs_remove(priv->node_tbl_root);
+		priv->node_tbl_root = NULL;
+		return;
+	}
+}
+
+/* hsr_debugfs_term - Tear down debugfs intrastructure
+ *
+ * Description:
+ * When Debugfs is configured this routine removes debugfs file system
+ * elements that are specific to hsr
+ */
+void
+hsr_debugfs_term(struct hsr_priv *priv)
+{
+	debugfs_remove_recursive(priv->node_tbl_root);
+	priv->node_tbl_root = NULL;
+}
+
+void hsr_debugfs_create_root(void)
+{
+	hsr_debugfs_root_dir = debugfs_create_dir("hsr", NULL);
+	if (IS_ERR(hsr_debugfs_root_dir)) {
+		pr_err("Cannot create hsr debugfs root directory\n");
+		hsr_debugfs_root_dir = NULL;
+	}
+}
+
+void hsr_debugfs_remove_root(void)
+{
+	/* debugfs_remove() internally checks NULL and ERROR */
+	debugfs_remove(hsr_debugfs_root_dir);
+}