[patch 6/7] process filtering for fault-injection capabilities

Akinobu Mita
2006-11-08T17:47:44Z

[-- Attachment #1: process-filter.patch --]
[-- Type: text/plain, Size: 5938 bytes --]

From: Akinobu Mita <akinobu.mita@gmail.com>

This patch provides process filtering feature.
The process filter allows failing only permitted processes
by /proc/<pid>/make-it-fail

Please see the example that demostrates how to inject slab allocation
failures into module init/cleanup code
in Documentation/fault-injection/fault-injection.txt

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>

fs/proc/base.c | 65 +++++++++++++++++++++++++++++++++++++++++++
include/linux/fault-inject.h | 2 +
include/linux/sched.h | 3 +
lib/fault-inject.c | 17 ++++++++++-
4 files changed, 86 insertions(+), 1 deletion(-)

Index: 2.6-rc/fs/proc/base.c
===================================================================
--- 2.6-rc.orig/fs/proc/base.c
+++ 2.6-rc/fs/proc/base.c
@@ -850,6 +850,65 @@ static struct file_operations proc_secco
};
#endif /* CONFIG_SECCOMP */

+#ifdef CONFIG_FAULT_INJECTION
+static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
+ char buffer[PROC_NUMBUF];
+ size_t len;
+ int make_it_fail;
+ loff_t __ppos = *ppos;
+
+ if (!task)
+ return -ESRCH;
+ make_it_fail = task->make_it_fail;
+ put_task_struct(task);
+
+ len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);
+ if (__ppos >= len)
+ return 0;
+ if (count > len-__ppos)
+ count = len-__ppos;
+ if (copy_to_user(buf, buffer + __ppos, count))
+ return -EFAULT;
+ *ppos = __ppos + count;
+ return count;
+}
+
+static ssize_t proc_fault_inject_write(struct file * file,
+ const char __user * buf, size_t count, loff_t *ppos)
+{
+ struct task_struct *task;
+ char buffer[PROC_NUMBUF], *end;
+ int make_it_fail;
+
+ if (!capable(CAP_SYS_RESOURCE))
+ return -EPERM;
+ memset(buffer, 0, sizeof(buffer));
+ if (count > sizeof(buffer) - 1)
+ count = sizeof(buffer) - 1;
+ if (copy_from_user(buffer, buf, count))
+ return -EFAULT;
+ make_it_fail = simple_strtol(buffer, &end, 0);
+ if (*end == '\n')
+ end++;
+ task = get_proc_task(file->f_dentry->d_inode);
+ if (!task)
+ return -ESRCH;
+ task->make_it_fail = make_it_fail;
+ put_task_struct(task);
+ if (end - buffer == 0)
+ return -EIO;
+ return end - buffer;
+}
+
+static struct file_operations proc_fault_inject_operations = {
+ .read = proc_fault_inject_read,
+ .write = proc_fault_inject_write,
+};
+#endif
+
static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;
@@ -1790,6 +1849,9 @@ static struct pid_entry tgid_base_stuff[
#ifdef CONFIG_AUDITSYSCALL
REG("loginuid", S_IWUSR|S_IRUGO, loginuid),
#endif
+#ifdef CONFIG_FAULT_INJECTION
+ REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
+#endif
};

static int proc_tgid_base_readdir(struct file * filp,
@@ -2064,6 +2126,9 @@ static struct pid_entry tid_base_stuff[]
#ifdef CONFIG_AUDITSYSCALL
REG("loginuid", S_IWUSR|S_IRUGO, loginuid),
#endif
+#ifdef CONFIG_FAULT_INJECTION
+ REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
+#endif
};

static int proc_tid_base_readdir(struct file * filp,
Index: 2.6-rc/include/linux/sched.h
===================================================================
--- 2.6-rc.orig/include/linux/sched.h
+++ 2.6-rc/include/linux/sched.h
@@ -1023,6 +1023,9 @@ struct task_struct {
#ifdef CONFIG_TASK_DELAY_ACCT
struct task_delay_info *delays;
#endif
+#ifdef CONFIG_FAULT_INJECTION
+ int make_it_fail;
+#endif
};

static inline pid_t process_group(struct task_struct *tsk)
Index: 2.6-rc/include/linux/fault-inject.h
===================================================================
--- 2.6-rc.orig/include/linux/fault-inject.h
+++ 2.6-rc/include/linux/fault-inject.h
@@ -17,6 +17,7 @@ struct fault_attr {
atomic_t times;
atomic_t space;
unsigned long verbose;
+ u32 task_filter;

unsigned long count;

@@ -30,6 +31,7 @@ struct fault_attr {
struct dentry *times_file;
struct dentry *space_file;
struct dentry *verbose_file;
+ struct dentry *task_filter_file;
} dentries;

#endif
Index: 2.6-rc/lib/fault-inject.c
===================================================================
--- 2.6-rc.orig/lib/fault-inject.c
+++ 2.6-rc/lib/fault-inject.c
@@ -5,6 +5,7 @@
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/module.h>
+#include <linux/interrupt.h>
#include <linux/fault-inject.h>

int setup_fault_attr(struct fault_attr *attr, char *str)
@@ -40,6 +41,11 @@ static void fail_dump(struct fault_attr

#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)

+static int fail_task(struct fault_attr *attr, struct task_struct *task)
+{
+ return !in_interrupt() && task->make_it_fail;
+}
+
/*
* This code is stolen from failmalloc-1.0
* http://www.nongnu.org/failmalloc/
@@ -47,6 +53,9 @@ static void fail_dump(struct fault_attr

int should_fail(struct fault_attr *attr, ssize_t size)
{
+ if (attr->task_filter && !fail_task(attr, current))
+ return 0;
+
if (atomic_read(&attr->times) == 0)
return 0;

@@ -131,6 +140,9 @@ void cleanup_fault_attr_dentries(struct
debugfs_remove(attr->dentries.verbose_file);
attr->dentries.verbose_file = NULL;

+ debugfs_remove(attr->dentries.task_filter_file);
+ attr->dentries.task_filter_file = NULL;
+
if (attr->dentries.dir)
WARN_ON(!simple_empty(attr->dentries.dir));

@@ -165,9 +177,12 @@ int init_fault_attr_dentries(struct faul
attr->dentries.verbose_file =
debugfs_create_ul("verbose", mode, dir, &attr->verbose);

+ attr->dentries.task_filter_file = debugfs_create_bool("task-filter",
+ mode, dir, &attr->task_filter);
+
if (!attr->dentries.probability_file || !attr->dentries.interval_file
|| !attr->dentries.times_file || !attr->dentries.space_file
- || !attr->dentries.verbose_file)
+ || !attr->dentries.verbose_file || !attr->dentries.task_filter_file)
goto fail;

return 0;

--