[PATCH 1/2][Precise] IB/security: Restrict use of the write() interface
Luis Henriques
luis.henriques at canonical.com
Thu May 26 11:20:11 UTC 2016
From: Jason Gunthorpe <jgunthorpe at obsidianresearch.com>
The drivers/infiniband stack uses write() as a replacement for
bi-directional ioctl(). This is not safe. There are ways to
trigger write calls that result in the return structure that
is normally written to user space being shunted off to user
specified kernel memory instead.
For the immediate repair, detect and deny suspicious accesses to
the write API.
For long term, update the user space libraries and the kernel API
to something that doesn't present the same security vulnerabilities
(likely a structured ioctl() interface).
The impacted uAPI interfaces are generally only available if
hardware from drivers/infiniband is installed in the system.
Reported-by: Jann Horn <jann at thejh.net>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Jason Gunthorpe <jgunthorpe at obsidianresearch.com>
[ Expanded check to all known write() entry points ]
Cc: stable at vger.kernel.org
Signed-off-by: Doug Ledford <dledford at redhat.com>
(backported from commit e6bd18f57aad1a2d1ef40e646d03ed0f2515c9e3)
[ luis:
- dropped changes to HFI driver which was merged in 4.3 only
- extra #include <rdma/ib.h> in ucma.c
- added file include/rdma/ib.h ]
CVE-2016-4565
BugLink: https://bugs.launchpad.net/bugs/1580372
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/infiniband/core/ucm.c | 4 +++
drivers/infiniband/core/ucma.c | 4 +++
drivers/infiniband/core/uverbs_main.c | 5 +++
drivers/infiniband/hw/qib/qib_file_ops.c | 5 +++
include/rdma/ib.h | 54 ++++++++++++++++++++++++++++++++
5 files changed, 72 insertions(+)
create mode 100644 include/rdma/ib.h
diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
index b8a0b4a7811b..06c116bdcca0 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -48,6 +48,7 @@
#include <asm/uaccess.h>
+#include <rdma/ib.h>
#include <rdma/ib_cm.h>
#include <rdma/ib_user_cm.h>
#include <rdma/ib_marshall.h>
@@ -1116,6 +1117,9 @@ static ssize_t ib_ucm_write(struct file *filp, const char __user *buf,
struct ib_ucm_cmd_hdr hdr;
ssize_t result;
+ if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+ return -EACCES;
+
if (len < sizeof(hdr))
return -EINVAL;
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index b37b0c02a7b9..91e82b7dadfa 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -47,6 +47,7 @@
#include <rdma/ib_marshall.h>
#include <rdma/rdma_cm.h>
#include <rdma/rdma_cm_ib.h>
+#include <rdma/ib.h>
MODULE_AUTHOR("Sean Hefty");
MODULE_DESCRIPTION("RDMA Userspace Connection Manager Access");
@@ -1268,6 +1269,9 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf,
struct rdma_ucm_cmd_hdr hdr;
ssize_t ret;
+ if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+ return -EACCES;
+
if (len < sizeof(hdr))
return -EINVAL;
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index f07c6e317771..9cdcb5038622 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -48,6 +48,8 @@
#include <asm/uaccess.h>
+#include <rdma/ib.h>
+
#include "uverbs.h"
MODULE_AUTHOR("Roland Dreier");
@@ -580,6 +582,9 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf,
struct ib_uverbs_file *file = filp->private_data;
struct ib_uverbs_cmd_hdr hdr;
+ if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+ return -EACCES;
+
if (count < sizeof hdr)
return -EINVAL;
diff --git a/drivers/infiniband/hw/qib/qib_file_ops.c b/drivers/infiniband/hw/qib/qib_file_ops.c
index a7403248d83d..81c5bdb194dc 100644
--- a/drivers/infiniband/hw/qib/qib_file_ops.c
+++ b/drivers/infiniband/hw/qib/qib_file_ops.c
@@ -45,6 +45,8 @@
#include <linux/delay.h>
#include <linux/export.h>
+#include <rdma/ib.h>
+
#include "qib.h"
#include "qib_common.h"
#include "qib_user_sdma.h"
@@ -1971,6 +1973,9 @@ static ssize_t qib_write(struct file *fp, const char __user *data,
ssize_t ret = 0;
void *dest;
+ if (WARN_ON_ONCE(!ib_safe_file_access(fp)))
+ return -EACCES;
+
if (count < sizeof(cmd.type)) {
ret = -EINVAL;
goto bail;
diff --git a/include/rdma/ib.h b/include/rdma/ib.h
new file mode 100644
index 000000000000..f09331ad0aba
--- /dev/null
+++ b/include/rdma/ib.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2010 Intel Corporation. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#if !defined(_RDMA_IB_H)
+#define _RDMA_IB_H
+
+#include <linux/types.h>
+#include <linux/sched.h>
+
+/*
+ * The IB interfaces that use write() as bi-directional ioctl() are
+ * fundamentally unsafe, since there are lots of ways to trigger "write()"
+ * calls from various contexts with elevated privileges. That includes the
+ * traditional suid executable error message writes, but also various kernel
+ * interfaces that can write to file descriptors.
+ *
+ * This function provides protection for the legacy API by restricting the
+ * calling context.
+ */
+static inline bool ib_safe_file_access(struct file *filp)
+{
+ return filp->f_cred == current_cred() && segment_eq(get_fs(), USER_DS);
+}
+
+#endif /* _RDMA_IB_H */
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