01/01: system: activate-ptrace-attach: Handle kernels without YAMA support.

[Mark H. Weaver]

mhw pushed a commit to branch master
in repository guix.

commit 15f0de0581987c539f86012bf524559e283f5942
Author: Mark H Weaver <address@hidden>
Date:   Sat May 9 12:57:36 2015 -0400

    system: activate-ptrace-attach: Handle kernels without YAMA support.
    
    * gnu/build/activation.scm (activate-ptrace-attach): Check for the existence
      of /proc/sys/kernel/yama/ptrace_scope before trying to write to it.
---
 gnu/build/activation.scm |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/gnu/build/activation.scm b/gnu/build/activation.scm
index 8697d9d..352e736 100644
--- a/gnu/build/activation.scm
+++ b/gnu/build/activation.scm
@@ -369,9 +369,11 @@ found in Linux 3.4 onward that prevents users from 
attaching to their own
 processes--see Yama.txt in the Linux source tree for the rationale.  This
 sounds like an unacceptable restriction for little or no security
 improvement."
-  (call-with-output-file "/proc/sys/kernel/yama/ptrace_scope"
-    (lambda (port)
-      (display 0 port))))
+  (let ((file "/proc/sys/kernel/yama/ptrace_scope"))
+    (when (file-exists? file)
+      (call-with-output-file file
+        (lambda (port)
+          (display 0 port))))))
 
 
 (define %current-system