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-rw-r--r--fs/proc/base.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index f1e1927ccd48..88b773f318cd 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1355,6 +1355,53 @@ static const struct file_operations proc_fault_inject_operations = {
.write = proc_fault_inject_write,
.llseek = generic_file_llseek,
};
+
+static ssize_t proc_fail_nth_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task;
+ int err, n;
+
+ task = get_proc_task(file_inode(file));
+ if (!task)
+ return -ESRCH;
+ put_task_struct(task);
+ if (task != current)
+ return -EPERM;
+ err = kstrtoint_from_user(buf, count, 10, &n);
+ if (err)
+ return err;
+ if (n < 0 || n == INT_MAX)
+ return -EINVAL;
+ current->fail_nth = n + 1;
+ return count;
+}
+
+static ssize_t proc_fail_nth_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task;
+ int err;
+
+ task = get_proc_task(file_inode(file));
+ if (!task)
+ return -ESRCH;
+ put_task_struct(task);
+ if (task != current)
+ return -EPERM;
+ if (count < 1)
+ return -EINVAL;
+ err = put_user((char)(current->fail_nth ? 'N' : 'Y'), buf);
+ if (err)
+ return err;
+ current->fail_nth = 0;
+ return 1;
+}
+
+static const struct file_operations proc_fail_nth_operations = {
+ .read = proc_fail_nth_read,
+ .write = proc_fail_nth_write,
+};
#endif
@@ -3311,6 +3358,11 @@ static const struct pid_entry tid_base_stuff[] = {
#endif
#ifdef CONFIG_FAULT_INJECTION
REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
+ /*
+ * Operations on the file check that the task is current,
+ * so we create it with 0666 to support testing under unprivileged user.
+ */
+ REG("fail-nth", 0666, proc_fail_nth_operations),
#endif
#ifdef CONFIG_TASK_IO_ACCOUNTING
ONE("io", S_IRUSR, proc_tid_io_accounting),