[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: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a3b50741..fd959d5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -853,6 +853,65 @@
};
#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 @@
#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 @@
#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,
diff --git a/include/linux/fault-inject.h b/include/linux/fault-inject.h
index 4df4902..a525f9b 100644
--- a/include/linux/fault-inject.h
+++ b/include/linux/fault-inject.h
@@ -17,6 +17,7 @@
atomic_t times;
atomic_t space;
unsigned long verbose;
+ u32 task_filter;
unsigned long count;
@@ -30,6 +31,7 @@
struct dentry *times_file;
struct dentry *space_file;
struct dentry *verbose_file;
+ struct dentry *task_filter_file;
} dentries;
#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f0317ed..ad9c460 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1045,6 +1045,9 @@
#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)
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index a7cb3af..0346860 100644
--- a/lib/fault-inject.c
+++ b/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>
/*
@@ -44,6 +45,11 @@
#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 @@
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 @@
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 @@
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;