Commit f4f154fd authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
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[PATCH] fault injection: process filtering for fault-injection capabilities 



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: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c17bb495

fs/proc/base.c

+65 −0
Original line number Diff line number Diff line
@@ -853,6 +853,65 @@ static struct file_operations proc_seccomp_operations = { 
};

#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;
@@ -1793,6 +1852,9 @@ 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,
@@ -2068,6 +2130,9 @@ 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,

include/linux/fault-inject.h

+2 −0
Original line number Diff line number Diff line
@@ -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

include/linux/sched.h

+3 −0
Original line number Diff line number Diff line
@@ -1045,6 +1045,9 @@ 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)

lib/fault-inject.c

+16 −1
Original line number Diff line number Diff line
@@ -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>



/*
@@ -44,6 +45,11 @@ static void fail_dump(struct fault_attr *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/
@@ -51,6 +57,9 @@ static void fail_dump(struct fault_attr *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;
@@ -135,6 +144,9 @@ void cleanup_fault_attr_dentries(struct fault_attr *attr) 
	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));
@@ -169,9 +181,12 @@ int init_fault_attr_dentries(struct fault_attr *attr, const char *name) 
	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;