+ if (need_suid_safe && cn.corename[0] != '/') {
+ printk(KERN_WARNING "Pid %d(%s) can only dump core "\
+ "to fully qualified path!\n",
+ task_tgid_vnr(current), current->comm);
+ printk(KERN_WARNING "Skipping core dump\n");
+ goto fail_unlock;
+ }
+
+ /*
+ * Unlink the file if it exists unless this is a SUID
+ * binary - in that case, we're running around with root
+ * privs and don't want to unlink another user's coredump.
+ */
+ if (!need_suid_safe) {
+ mm_segment_t old_fs;
+
+ old_fs = get_fs();
+ set_fs(KERNEL_DS);
+ /*
+ * If it doesn't exist, that's fine. If there's some
+ * other problem, we'll catch it at the filp_open().
+ */
+ (void) sys_unlink((const char __user *)cn.corename);
+ set_fs(old_fs);
+ }
+
+ /*
+ * There is a race between unlinking and creating the
+ * file, but if that causes an EEXIST here, that's
+ * fine - another process raced with us while creating
+ * the corefile, and the other process won. To userspace,
+ * what matters is that at least one of the two processes
+ * writes its coredump successfully, not which one.
+ */
+ if (need_suid_safe) {
+ /*
+ * Using user namespaces, normal user tasks can change
+ * their current->fs->root to point to arbitrary
+ * directories. Since the intention of the "only dump
+ * with a fully qualified path" rule is to control where
+ * coredumps may be placed using root privileges,
+ * current->fs->root must not be used. Instead, use the
+ * root directory of init_task.
+ */
+ struct path root;
+
+ task_lock(&init_task);
+ get_fs_root(init_task.fs, &root);
+ task_unlock(&init_task);
+ cprm.file = file_open_root(root.dentry, root.mnt,
+ cn.corename, open_flags, 0600);
+ path_put(&root);
+ } else {
+ cprm.file = filp_open(cn.corename, open_flags, 0600);
+ }