linux/kernel/fail_function.c
Kees Cook 6da2ec5605 treewide: kmalloc() -> kmalloc_array()
The kmalloc() function has a 2-factor argument form, kmalloc_array(). This
patch replaces cases of:

        kmalloc(a * b, gfp)

with:
        kmalloc_array(a * b, gfp)

as well as handling cases of:

        kmalloc(a * b * c, gfp)

with:

        kmalloc(array3_size(a, b, c), gfp)

as it's slightly less ugly than:

        kmalloc_array(array_size(a, b), c, gfp)

This does, however, attempt to ignore constant size factors like:

        kmalloc(4 * 1024, gfp)

though any constants defined via macros get caught up in the conversion.

Any factors with a sizeof() of "unsigned char", "char", and "u8" were
dropped, since they're redundant.

The tools/ directory was manually excluded, since it has its own
implementation of kmalloc().

The Coccinelle script used for this was:

// Fix redundant parens around sizeof().
@@
type TYPE;
expression THING, E;
@@

(
  kmalloc(
-	(sizeof(TYPE)) * E
+	sizeof(TYPE) * E
  , ...)
|
  kmalloc(
-	(sizeof(THING)) * E
+	sizeof(THING) * E
  , ...)
)

// Drop single-byte sizes and redundant parens.
@@
expression COUNT;
typedef u8;
typedef __u8;
@@

(
  kmalloc(
-	sizeof(u8) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(__u8) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(char) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(unsigned char) * (COUNT)
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(u8) * COUNT
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(__u8) * COUNT
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(char) * COUNT
+	COUNT
  , ...)
|
  kmalloc(
-	sizeof(unsigned char) * COUNT
+	COUNT
  , ...)
)

// 2-factor product with sizeof(type/expression) and identifier or constant.
@@
type TYPE;
expression THING;
identifier COUNT_ID;
constant COUNT_CONST;
@@

(
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * (COUNT_ID)
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * COUNT_ID
+	COUNT_ID, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * (COUNT_CONST)
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * COUNT_CONST
+	COUNT_CONST, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * (COUNT_ID)
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * COUNT_ID
+	COUNT_ID, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * (COUNT_CONST)
+	COUNT_CONST, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * COUNT_CONST
+	COUNT_CONST, sizeof(THING)
  , ...)
)

// 2-factor product, only identifiers.
@@
identifier SIZE, COUNT;
@@

- kmalloc
+ kmalloc_array
  (
-	SIZE * COUNT
+	COUNT, SIZE
  , ...)

// 3-factor product with 1 sizeof(type) or sizeof(expression), with
// redundant parens removed.
@@
expression THING;
identifier STRIDE, COUNT;
type TYPE;
@@

(
  kmalloc(
-	sizeof(TYPE) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(TYPE) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(TYPE) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(TYPE) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(TYPE))
  , ...)
|
  kmalloc(
-	sizeof(THING) * (COUNT) * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kmalloc(
-	sizeof(THING) * (COUNT) * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kmalloc(
-	sizeof(THING) * COUNT * (STRIDE)
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
|
  kmalloc(
-	sizeof(THING) * COUNT * STRIDE
+	array3_size(COUNT, STRIDE, sizeof(THING))
  , ...)
)

// 3-factor product with 2 sizeof(variable), with redundant parens removed.
@@
expression THING1, THING2;
identifier COUNT;
type TYPE1, TYPE2;
@@

(
  kmalloc(
-	sizeof(TYPE1) * sizeof(TYPE2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kmalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2))
  , ...)
|
  kmalloc(
-	sizeof(THING1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kmalloc(
-	sizeof(THING1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(THING1), sizeof(THING2))
  , ...)
|
  kmalloc(
-	sizeof(TYPE1) * sizeof(THING2) * COUNT
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
|
  kmalloc(
-	sizeof(TYPE1) * sizeof(THING2) * (COUNT)
+	array3_size(COUNT, sizeof(TYPE1), sizeof(THING2))
  , ...)
)

// 3-factor product, only identifiers, with redundant parens removed.
@@
identifier STRIDE, SIZE, COUNT;
@@

(
  kmalloc(
-	(COUNT) * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	(COUNT) * (STRIDE) * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	(COUNT) * STRIDE * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	(COUNT) * (STRIDE) * (SIZE)
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
|
  kmalloc(
-	COUNT * STRIDE * SIZE
+	array3_size(COUNT, STRIDE, SIZE)
  , ...)
)

// Any remaining multi-factor products, first at least 3-factor products,
// when they're not all constants...
@@
expression E1, E2, E3;
constant C1, C2, C3;
@@

(
  kmalloc(C1 * C2 * C3, ...)
|
  kmalloc(
-	(E1) * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kmalloc(
-	(E1) * (E2) * E3
+	array3_size(E1, E2, E3)
  , ...)
|
  kmalloc(
-	(E1) * (E2) * (E3)
+	array3_size(E1, E2, E3)
  , ...)
|
  kmalloc(
-	E1 * E2 * E3
+	array3_size(E1, E2, E3)
  , ...)
)

// And then all remaining 2 factors products when they're not all constants,
// keeping sizeof() as the second factor argument.
@@
expression THING, E1, E2;
type TYPE;
constant C1, C2, C3;
@@

(
  kmalloc(sizeof(THING) * C2, ...)
|
  kmalloc(sizeof(TYPE) * C2, ...)
|
  kmalloc(C1 * C2 * C3, ...)
|
  kmalloc(C1 * C2, ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * (E2)
+	E2, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(TYPE) * E2
+	E2, sizeof(TYPE)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * (E2)
+	E2, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	sizeof(THING) * E2
+	E2, sizeof(THING)
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	(E1) * E2
+	E1, E2
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	(E1) * (E2)
+	E1, E2
  , ...)
|
- kmalloc
+ kmalloc_array
  (
-	E1 * E2
+	E1, E2
  , ...)
)

Signed-off-by: Kees Cook <keescook@chromium.org>
2018-06-12 16:19:22 -07:00

360 lines
7.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* fail_function.c: Function-based error injection
*/
#include <linux/error-injection.h>
#include <linux/debugfs.h>
#include <linux/fault-inject.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs,
unsigned long flags)
{
/*
* A dummy post handler is required to prohibit optimizing, because
* jump optimization does not support execution path overriding.
*/
}
struct fei_attr {
struct list_head list;
struct kprobe kp;
unsigned long retval;
};
static DEFINE_MUTEX(fei_lock);
static LIST_HEAD(fei_attr_list);
static DECLARE_FAULT_ATTR(fei_fault_attr);
static struct dentry *fei_debugfs_dir;
static unsigned long adjust_error_retval(unsigned long addr, unsigned long retv)
{
switch (get_injectable_error_type(addr)) {
case EI_ETYPE_NULL:
if (retv != 0)
return 0;
break;
case EI_ETYPE_ERRNO:
if (retv < (unsigned long)-MAX_ERRNO)
return (unsigned long)-EINVAL;
break;
case EI_ETYPE_ERRNO_NULL:
if (retv != 0 && retv < (unsigned long)-MAX_ERRNO)
return (unsigned long)-EINVAL;
break;
}
return retv;
}
static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr)
{
struct fei_attr *attr;
attr = kzalloc(sizeof(*attr), GFP_KERNEL);
if (attr) {
attr->kp.symbol_name = kstrdup(sym, GFP_KERNEL);
if (!attr->kp.symbol_name) {
kfree(attr);
return NULL;
}
attr->kp.pre_handler = fei_kprobe_handler;
attr->kp.post_handler = fei_post_handler;
attr->retval = adjust_error_retval(addr, 0);
INIT_LIST_HEAD(&attr->list);
}
return attr;
}
static void fei_attr_free(struct fei_attr *attr)
{
if (attr) {
kfree(attr->kp.symbol_name);
kfree(attr);
}
}
static struct fei_attr *fei_attr_lookup(const char *sym)
{
struct fei_attr *attr;
list_for_each_entry(attr, &fei_attr_list, list) {
if (!strcmp(attr->kp.symbol_name, sym))
return attr;
}
return NULL;
}
static bool fei_attr_is_valid(struct fei_attr *_attr)
{
struct fei_attr *attr;
list_for_each_entry(attr, &fei_attr_list, list) {
if (attr == _attr)
return true;
}
return false;
}
static int fei_retval_set(void *data, u64 val)
{
struct fei_attr *attr = data;
unsigned long retv = (unsigned long)val;
int err = 0;
mutex_lock(&fei_lock);
/*
* Since this operation can be done after retval file is removed,
* It is safer to check the attr is still valid before accessing
* its member.
*/
if (!fei_attr_is_valid(attr)) {
err = -ENOENT;
goto out;
}
if (attr->kp.addr) {
if (adjust_error_retval((unsigned long)attr->kp.addr,
val) != retv)
err = -EINVAL;
}
if (!err)
attr->retval = val;
out:
mutex_unlock(&fei_lock);
return err;
}
static int fei_retval_get(void *data, u64 *val)
{
struct fei_attr *attr = data;
int err = 0;
mutex_lock(&fei_lock);
/* Here we also validate @attr to ensure it still exists. */
if (!fei_attr_is_valid(attr))
err = -ENOENT;
else
*val = attr->retval;
mutex_unlock(&fei_lock);
return err;
}
DEFINE_DEBUGFS_ATTRIBUTE(fei_retval_ops, fei_retval_get, fei_retval_set,
"%llx\n");
static int fei_debugfs_add_attr(struct fei_attr *attr)
{
struct dentry *dir;
dir = debugfs_create_dir(attr->kp.symbol_name, fei_debugfs_dir);
if (!dir)
return -ENOMEM;
if (!debugfs_create_file("retval", 0600, dir, attr, &fei_retval_ops)) {
debugfs_remove_recursive(dir);
return -ENOMEM;
}
return 0;
}
static void fei_debugfs_remove_attr(struct fei_attr *attr)
{
struct dentry *dir;
dir = debugfs_lookup(attr->kp.symbol_name, fei_debugfs_dir);
if (dir)
debugfs_remove_recursive(dir);
}
static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
{
struct fei_attr *attr = container_of(kp, struct fei_attr, kp);
if (should_fail(&fei_fault_attr, 1)) {
regs_set_return_value(regs, attr->retval);
override_function_with_return(regs);
/* Kprobe specific fixup */
reset_current_kprobe();
preempt_enable_no_resched();
return 1;
}
return 0;
}
NOKPROBE_SYMBOL(fei_kprobe_handler)
static void *fei_seq_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&fei_lock);
return seq_list_start(&fei_attr_list, *pos);
}
static void fei_seq_stop(struct seq_file *m, void *v)
{
mutex_unlock(&fei_lock);
}
static void *fei_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &fei_attr_list, pos);
}
static int fei_seq_show(struct seq_file *m, void *v)
{
struct fei_attr *attr = list_entry(v, struct fei_attr, list);
seq_printf(m, "%pf\n", attr->kp.addr);
return 0;
}
static const struct seq_operations fei_seq_ops = {
.start = fei_seq_start,
.next = fei_seq_next,
.stop = fei_seq_stop,
.show = fei_seq_show,
};
static int fei_open(struct inode *inode, struct file *file)
{
return seq_open(file, &fei_seq_ops);
}
static void fei_attr_remove(struct fei_attr *attr)
{
fei_debugfs_remove_attr(attr);
unregister_kprobe(&attr->kp);
list_del(&attr->list);
fei_attr_free(attr);
}
static void fei_attr_remove_all(void)
{
struct fei_attr *attr, *n;
list_for_each_entry_safe(attr, n, &fei_attr_list, list) {
fei_attr_remove(attr);
}
}
static ssize_t fei_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
struct fei_attr *attr;
unsigned long addr;
char *buf, *sym;
int ret;
/* cut off if it is too long */
if (count > KSYM_NAME_LEN)
count = KSYM_NAME_LEN;
buf = kmalloc(count + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, buffer, count)) {
ret = -EFAULT;
goto out;
}
buf[count] = '\0';
sym = strstrip(buf);
mutex_lock(&fei_lock);
/* Writing just spaces will remove all injection points */
if (sym[0] == '\0') {
fei_attr_remove_all();
ret = count;
goto out;
}
/* Writing !function will remove one injection point */
if (sym[0] == '!') {
attr = fei_attr_lookup(sym + 1);
if (!attr) {
ret = -ENOENT;
goto out;
}
fei_attr_remove(attr);
ret = count;
goto out;
}
addr = kallsyms_lookup_name(sym);
if (!addr) {
ret = -EINVAL;
goto out;
}
if (!within_error_injection_list(addr)) {
ret = -ERANGE;
goto out;
}
if (fei_attr_lookup(sym)) {
ret = -EBUSY;
goto out;
}
attr = fei_attr_new(sym, addr);
if (!attr) {
ret = -ENOMEM;
goto out;
}
ret = register_kprobe(&attr->kp);
if (!ret)
ret = fei_debugfs_add_attr(attr);
if (ret < 0)
fei_attr_remove(attr);
else {
list_add_tail(&attr->list, &fei_attr_list);
ret = count;
}
out:
kfree(buf);
mutex_unlock(&fei_lock);
return ret;
}
static const struct file_operations fei_ops = {
.open = fei_open,
.read = seq_read,
.write = fei_write,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init fei_debugfs_init(void)
{
struct dentry *dir;
dir = fault_create_debugfs_attr("fail_function", NULL,
&fei_fault_attr);
if (IS_ERR(dir))
return PTR_ERR(dir);
/* injectable attribute is just a symlink of error_inject/list */
if (!debugfs_create_symlink("injectable", dir,
"../error_injection/list"))
goto error;
if (!debugfs_create_file("inject", 0600, dir, NULL, &fei_ops))
goto error;
fei_debugfs_dir = dir;
return 0;
error:
debugfs_remove_recursive(dir);
return -ENOMEM;
}
late_initcall(fei_debugfs_init);