[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>

1 files changed, 65 insertions, 0 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index a3b5074118a7..fd959d5b5a80 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -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,