+static ssize_t comm_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *offset)
+{
+ struct inode *inode = file->f_path.dentry->d_inode;
+ struct task_struct *p;
+ char buffer[TASK_COMM_LEN];
+
+ memset(buffer, 0, sizeof(buffer));
+ if (count > sizeof(buffer) - 1)
+ count = sizeof(buffer) - 1;
+ if (copy_from_user(buffer, buf, count))
+ return -EFAULT;
+
+ p = get_proc_task(inode);
+ if (!p)
+ return -ESRCH;
+
+ if (same_thread_group(current, p))
+ set_task_comm(p, buffer);
+ else
+ count = -EINVAL;
+
+ put_task_struct(p);
+
+ return count;
+}
+
+static int comm_show(struct seq_file *m, void *v)
+{
+ struct inode *inode = m->private;
+ struct task_struct *p;
+
+ p = get_proc_task(inode);
+ if (!p)
+ return -ESRCH;
+
+ task_lock(p);
+ seq_printf(m, "%s\n", p->comm);
+ task_unlock(p);
+
+ put_task_struct(p);
+
+ return 0;
+}
+
+static int comm_open(struct inode *inode, struct file *filp)
+{
+ int ret;
+
+ ret = single_open(filp, comm_show, NULL);
+ if (!ret) {
+ struct seq_file *m = filp->private_data;
+
+ m->private = inode;
+ }
+ return ret;
+}
+
+static const struct file_operations proc_pid_set_comm_operations = {
+ .open = comm_open,
+ .read = seq_read,
+ .write = comm_write,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+/*
+ * We added or removed a vma mapping the executable. The vmas are only mapped
+ * during exec and are not mapped with the mmap system call.
+ * Callers must hold down_write() on the mm's mmap_sem for these
+ */
+void added_exe_file_vma(struct mm_struct *mm)
+{
+ mm->num_exe_file_vmas++;
+}
+
+void removed_exe_file_vma(struct mm_struct *mm)
+{
+ mm->num_exe_file_vmas--;
+ if ((mm->num_exe_file_vmas == 0) && mm->exe_file){
+ fput(mm->exe_file);
+ mm->exe_file = NULL;
+ }
+
+}
+
+void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
+{
+ if (new_exe_file)
+ get_file(new_exe_file);
+ if (mm->exe_file)
+ fput(mm->exe_file);
+ mm->exe_file = new_exe_file;
+ mm->num_exe_file_vmas = 0;
+}
+
+struct file *get_mm_exe_file(struct mm_struct *mm)
+{
+ struct file *exe_file;
+
+ /* We need mmap_sem to protect against races with removal of
+ * VM_EXECUTABLE vmas */
+ down_read(&mm->mmap_sem);
+ exe_file = mm->exe_file;
+ if (exe_file)
+ get_file(exe_file);
+ up_read(&mm->mmap_sem);
+ return exe_file;
+}
+
+void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
+{
+ /* It's safe to write the exe_file pointer without exe_file_lock because
+ * this is called during fork when the task is not yet in /proc */
+ newmm->exe_file = get_mm_exe_file(oldmm);
+}
+
+static int proc_exe_link(struct inode *inode, struct path *exe_path)
+{
+ struct task_struct *task;
+ struct mm_struct *mm;
+ struct file *exe_file;
+
+ task = get_proc_task(inode);
+ if (!task)
+ return -ENOENT;
+ mm = get_task_mm(task);
+ put_task_struct(task);
+ if (!mm)
+ return -ENOENT;
+ exe_file = get_mm_exe_file(mm);
+ mmput(mm);
+ if (exe_file) {
+ *exe_path = exe_file->f_path;
+ path_get(&exe_file->f_path);
+ fput(exe_file);
+ return 0;
+ } else
+ return -ENOENT;
+}
+