Merge branch 'next-seccomp' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris...
[sfrench/cifs-2.6.git] / kernel / seccomp.c
index 3153c9e..940fa40 100644 (file)
@@ -978,49 +978,68 @@ long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
 }
 
 #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
-long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
-                       void __user *data)
+static struct seccomp_filter *get_nth_filter(struct task_struct *task,
+                                            unsigned long filter_off)
 {
-       struct seccomp_filter *filter;
-       struct sock_fprog_kern *fprog;
-       long ret;
-       unsigned long count = 0;
-
-       if (!capable(CAP_SYS_ADMIN) ||
-           current->seccomp.mode != SECCOMP_MODE_DISABLED) {
-               return -EACCES;
-       }
+       struct seccomp_filter *orig, *filter;
+       unsigned long count;
 
+       /*
+        * Note: this is only correct because the caller should be the (ptrace)
+        * tracer of the task, otherwise lock_task_sighand is needed.
+        */
        spin_lock_irq(&task->sighand->siglock);
+
        if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
-               ret = -EINVAL;
-               goto out;
+               spin_unlock_irq(&task->sighand->siglock);
+               return ERR_PTR(-EINVAL);
        }
 
-       filter = task->seccomp.filter;
-       while (filter) {
-               filter = filter->prev;
+       orig = task->seccomp.filter;
+       __get_seccomp_filter(orig);
+       spin_unlock_irq(&task->sighand->siglock);
+
+       count = 0;
+       for (filter = orig; filter; filter = filter->prev)
                count++;
-       }
 
        if (filter_off >= count) {
-               ret = -ENOENT;
+               filter = ERR_PTR(-ENOENT);
                goto out;
        }
-       count -= filter_off;
 
-       filter = task->seccomp.filter;
-       while (filter && count > 1) {
-               filter = filter->prev;
+       count -= filter_off;
+       for (filter = orig; filter && count > 1; filter = filter->prev)
                count--;
-       }
 
        if (WARN_ON(count != 1 || !filter)) {
-               /* The filter tree shouldn't shrink while we're using it. */
-               ret = -ENOENT;
+               filter = ERR_PTR(-ENOENT);
                goto out;
        }
 
+       __get_seccomp_filter(filter);
+
+out:
+       __put_seccomp_filter(orig);
+       return filter;
+}
+
+long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
+                       void __user *data)
+{
+       struct seccomp_filter *filter;
+       struct sock_fprog_kern *fprog;
+       long ret;
+
+       if (!capable(CAP_SYS_ADMIN) ||
+           current->seccomp.mode != SECCOMP_MODE_DISABLED) {
+               return -EACCES;
+       }
+
+       filter = get_nth_filter(task, filter_off);
+       if (IS_ERR(filter))
+               return PTR_ERR(filter);
+
        fprog = filter->prog->orig_prog;
        if (!fprog) {
                /* This must be a new non-cBPF filter, since we save
@@ -1035,17 +1054,44 @@ long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
        if (!data)
                goto out;
 
-       __get_seccomp_filter(filter);
-       spin_unlock_irq(&task->sighand->siglock);
-
        if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
                ret = -EFAULT;
 
+out:
        __put_seccomp_filter(filter);
        return ret;
+}
 
-out:
-       spin_unlock_irq(&task->sighand->siglock);
+long seccomp_get_metadata(struct task_struct *task,
+                         unsigned long size, void __user *data)
+{
+       long ret;
+       struct seccomp_filter *filter;
+       struct seccomp_metadata kmd = {};
+
+       if (!capable(CAP_SYS_ADMIN) ||
+           current->seccomp.mode != SECCOMP_MODE_DISABLED) {
+               return -EACCES;
+       }
+
+       size = min_t(unsigned long, size, sizeof(kmd));
+
+       if (copy_from_user(&kmd, data, size))
+               return -EFAULT;
+
+       filter = get_nth_filter(task, kmd.filter_off);
+       if (IS_ERR(filter))
+               return PTR_ERR(filter);
+
+       memset(&kmd, 0, sizeof(kmd));
+       if (filter->log)
+               kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
+
+       ret = size;
+       if (copy_to_user(data, &kmd, size))
+               ret = -EFAULT;
+
+       __put_seccomp_filter(filter);
        return ret;
 }
 #endif