[lttng-dev] [PATCH lttng-modules 1/4] Fix: Remove 'type' argument from access_ok() function (v5.0)
Michael Jeanson
mjeanson at efficios.com
Wed Jan 9 14:59:15 EST 2019
See upstream commit :
commit 96d4f267e40f9509e8a66e2b39e8b95655617693
Author: Linus Torvalds <torvalds at linux-foundation.org>
Date: Thu Jan 3 18:57:57 2019 -0800
Remove 'type' argument from access_ok() function
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Michael Jeanson <mjeanson at efficios.com>
---
lib/ringbuffer/backend.h | 8 ++++----
lib/ringbuffer/ring_buffer_iterator.c | 3 ++-
lttng-filter-interpreter.c | 4 ++--
probes/lttng-probe-user.c | 3 ++-
wrapper/uaccess.h | 28 +++++++++++++++++++++++++++
5 files changed, 38 insertions(+), 8 deletions(-)
create mode 100644 wrapper/uaccess.h
diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h
index 501fad4..da937f2 100644
--- a/lib/ringbuffer/backend.h
+++ b/lib/ringbuffer/backend.h
@@ -21,7 +21,7 @@
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/mm.h>
-#include <linux/uaccess.h>
+#include <wrapper/uaccess.h>
/* Internal helpers */
#include <wrapper/ringbuffer/backend_internal.h>
@@ -289,7 +289,7 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config
set_fs(KERNEL_DS);
pagefault_disable();
- if (unlikely(!access_ok(VERIFY_READ, src, len)))
+ if (unlikely(!lttng_access_ok(VERIFY_READ, src, len)))
goto fill_buffer;
if (likely(pagecpy == len)) {
@@ -359,7 +359,7 @@ void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_conf
set_fs(KERNEL_DS);
pagefault_disable();
- if (unlikely(!access_ok(VERIFY_READ, src, len)))
+ if (unlikely(!lttng_access_ok(VERIFY_READ, src, len)))
goto fill_buffer;
if (likely(pagecpy == len)) {
@@ -449,7 +449,7 @@ unsigned long lib_ring_buffer_copy_from_user_check_nofault(void *dest,
unsigned long ret;
mm_segment_t old_fs;
- if (!access_ok(VERIFY_READ, src, len))
+ if (!lttng_access_ok(VERIFY_READ, src, len))
return 1;
old_fs = get_fs();
set_fs(KERNEL_DS);
diff --git a/lib/ringbuffer/ring_buffer_iterator.c b/lib/ringbuffer/ring_buffer_iterator.c
index 9efe491..d25db72 100644
--- a/lib/ringbuffer/ring_buffer_iterator.c
+++ b/lib/ringbuffer/ring_buffer_iterator.c
@@ -11,6 +11,7 @@
#include <wrapper/ringbuffer/iterator.h>
#include <wrapper/file.h>
+#include <wrapper/uaccess.h>
#include <linux/jiffies.h>
#include <linux/delay.h>
#include <linux/module.h>
@@ -605,7 +606,7 @@ ssize_t channel_ring_buffer_file_read(struct file *filp,
ssize_t len;
might_sleep();
- if (!access_ok(VERIFY_WRITE, user_buf, count))
+ if (!lttng_access_ok(VERIFY_WRITE, user_buf, count))
return -EFAULT;
/* Finish copy of previous record */
diff --git a/lttng-filter-interpreter.c b/lttng-filter-interpreter.c
index bf69549..3dad6cc 100644
--- a/lttng-filter-interpreter.c
+++ b/lttng-filter-interpreter.c
@@ -7,7 +7,7 @@
* Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
*/
-#include <linux/uaccess.h>
+#include <wrapper/uaccess.h>
#include <wrapper/frame.h>
#include <wrapper/types.h>
#include <linux/swab.h>
@@ -30,7 +30,7 @@ char get_char(struct estack_entry *reg, size_t offset)
char c;
/* Handle invalid access as end of string. */
- if (unlikely(!access_ok(VERIFY_READ,
+ if (unlikely(!lttng_access_ok(VERIFY_READ,
reg->u.s.user_str + offset,
sizeof(c))))
return '\0';
diff --git a/probes/lttng-probe-user.c b/probes/lttng-probe-user.c
index 4162a7e..0d1f95f 100644
--- a/probes/lttng-probe-user.c
+++ b/probes/lttng-probe-user.c
@@ -7,6 +7,7 @@
#include <linux/uaccess.h>
#include <linux/module.h>
+#include <wrapper/uaccess.h>
#include <probes/lttng-probe-user.h>
/*
@@ -30,7 +31,7 @@ long lttng_strlen_user_inatomic(const char *addr)
char v;
unsigned long ret;
- if (unlikely(!access_ok(VERIFY_READ,
+ if (unlikely(!lttng_access_ok(VERIFY_READ,
(__force const char __user *) addr,
sizeof(v))))
break;
diff --git a/wrapper/uaccess.h b/wrapper/uaccess.h
new file mode 100644
index 0000000..c56427c
--- /dev/null
+++ b/wrapper/uaccess.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
+ * wrapper/uaccess.h
+ *
+ * wrapper around linux/uaccess.h.
+ *
+ * Copyright (C) 2019 Michael Jeanson <mjeanson at efficios.com>
+ */
+
+#ifndef _LTTNG_WRAPPER_UACCESS_H
+#define _LTTNG_WRAPPER_UACCESS_H
+
+#include <linux/uaccess.h>
+#include <lttng-kernel-version.h>
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,0,0))
+
+#define VERIFY_READ 0
+#define VERIFY_WRITE 1
+#define lttng_access_ok(type, addr, size) access_ok(addr, size)
+
+#else /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,0,0) */
+
+#define lttng_access_ok(type, addr, size) access_ok(type, addr, size)
+
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(5,0,0) */
+
+#endif /* _LTTNG_WRAPPER_UACCESS_H */
--
2.17.1
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