[PATCH] selinux: tracer SID fix

Fix SELinux to not reset the tracer SID when the child is already being
traced, since selinux_ptrace is also called by proc for access checking
outside of the context of a ptrace attach.

Signed-off-by: Stephen Smalley <[e-mail]>
Acked-by: James Morris <[e-mail]>
Acked-by: Chris Wright <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

security/selinux/hooks.c

···
 
 	rc = task_has_perm(parent, child, PROCESS__PTRACE);
 	/* Save the SID of the tracing process for later use in apply_creds. */
-	if (!rc)
+	if (!(child->ptrace & PT_PTRACED) && !rc)
 		csec->ptrace_sid = psec->sid;
 	return rc;
 }