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, 197 insertions, 0 deletions

diff --git a/fs/xfs/xfs_sysctl.c b/fs/xfs/xfs_sysctl.c
new file mode 100644
index 000000000..7f32d282d
--- /dev/null
+++ b/fs/xfs/xfs_sysctl.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2001-2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#include "xfs_platform.h"
+#include "xfs_error.h"
+
+static struct ctl_table_header *xfs_table_header;
+
+#ifdef CONFIG_PROC_FS
+STATIC int
+xfs_stats_clear_proc_handler(
+	const struct ctl_table	*ctl,
+	int			write,
+	void			*buffer,
+	size_t			*lenp,
+	loff_t			*ppos)
+{
+	int		ret, *valp = ctl->data;
+
+	ret = proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
+
+	if (!ret && write && *valp) {
+		xfs_stats_clearall(xfsstats.xs_stats);
+		xfs_stats_clear = 0;
+	}
+
+	return ret;
+}
+
+STATIC int
+xfs_panic_mask_proc_handler(
+	const struct ctl_table	*ctl,
+	int			write,
+	void			*buffer,
+	size_t			*lenp,
+	loff_t			*ppos)
+{
+	int		ret, *valp = ctl->data;
+
+	ret = proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
+	if (!ret && write) {
+		xfs_panic_mask = *valp;
+#ifdef DEBUG
+		xfs_panic_mask |= (XFS_PTAG_SHUTDOWN_CORRUPT | XFS_PTAG_LOGRES);
+#endif
+	}
+	return ret;
+}
+#endif /* CONFIG_PROC_FS */
+
+static inline int
+xfs_deprecated_dointvec_minmax(
+	const struct ctl_table	*ctl,
+	int			write,
+	void			*buffer,
+	size_t			*lenp,
+	loff_t			*ppos)
+{
+	if (write) {
+		printk_ratelimited(KERN_WARNING
+				"XFS: %s sysctl option is deprecated.\n",
+				ctl->procname);
+	}
+	return proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
+}
+
+static const struct ctl_table xfs_table[] = {
+	{
+		.procname	= "panic_mask",
+		.data		= &xfs_params.panic_mask.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= xfs_panic_mask_proc_handler,
+		.extra1		= &xfs_params.panic_mask.min,
+		.extra2		= &xfs_params.panic_mask.max
+	},
+
+	{
+		.procname	= "error_level",
+		.data		= &xfs_params.error_level.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.error_level.min,
+		.extra2		= &xfs_params.error_level.max
+	},
+	{
+		.procname	= "xfssyncd_centisecs",
+		.data		= &xfs_params.syncd_timer.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.syncd_timer.min,
+		.extra2		= &xfs_params.syncd_timer.max
+	},
+	{
+		.procname	= "inherit_sync",
+		.data		= &xfs_params.inherit_sync.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.inherit_sync.min,
+		.extra2		= &xfs_params.inherit_sync.max
+	},
+	{
+		.procname	= "inherit_nodump",
+		.data		= &xfs_params.inherit_nodump.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.inherit_nodump.min,
+		.extra2		= &xfs_params.inherit_nodump.max
+	},
+	{
+		.procname	= "inherit_noatime",
+		.data		= &xfs_params.inherit_noatim.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.inherit_noatim.min,
+		.extra2		= &xfs_params.inherit_noatim.max
+	},
+	{
+		.procname	= "inherit_nosymlinks",
+		.data		= &xfs_params.inherit_nosym.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.inherit_nosym.min,
+		.extra2		= &xfs_params.inherit_nosym.max
+	},
+	{
+		.procname	= "rotorstep",
+		.data		= &xfs_params.rotorstep.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.rotorstep.min,
+		.extra2		= &xfs_params.rotorstep.max
+	},
+	{
+		.procname	= "inherit_nodefrag",
+		.data		= &xfs_params.inherit_nodfrg.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.inherit_nodfrg.min,
+		.extra2		= &xfs_params.inherit_nodfrg.max
+	},
+	{
+		.procname	= "filestream_centisecs",
+		.data		= &xfs_params.fstrm_timer.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.fstrm_timer.min,
+		.extra2		= &xfs_params.fstrm_timer.max,
+	},
+	{
+		.procname	= "speculative_prealloc_lifetime",
+		.data		= &xfs_params.blockgc_timer.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &xfs_params.blockgc_timer.min,
+		.extra2		= &xfs_params.blockgc_timer.max,
+	},
+	/* please keep this the last entry */
+#ifdef CONFIG_PROC_FS
+	{
+		.procname	= "stats_clear",
+		.data		= &xfs_params.stats_clear.val,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= xfs_stats_clear_proc_handler,
+		.extra1		= &xfs_params.stats_clear.min,
+		.extra2		= &xfs_params.stats_clear.max
+	},
+#endif /* CONFIG_PROC_FS */
+};
+
+int
+xfs_sysctl_register(void)
+{
+	xfs_table_header = register_sysctl("fs/xfs", xfs_table);
+	if (!xfs_table_header)
+		return -ENOMEM;
+	return 0;
+}
+
+void
+xfs_sysctl_unregister(void)
+{
+	unregister_sysctl_table(xfs_table_header);
+}