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-rw-r--r--security/yama/yama_lsm.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 0309f2111c70..968e5e0a3f81 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -309,7 +309,7 @@ static int task_is_descendant(struct task_struct *parent,
* @tracer: the task_struct of the process attempting ptrace
* @tracee: the task_struct of the process to be ptraced
*
- * Returns 1 if tracer has is ptracer exception ancestor for tracee.
+ * Returns 1 if tracer has a ptracer exception ancestor for tracee.
*/
static int ptracer_exception_found(struct task_struct *tracer,
struct task_struct *tracee)
@@ -320,6 +320,18 @@ static int ptracer_exception_found(struct task_struct *tracer,
bool found = false;
rcu_read_lock();
+
+ /*
+ * If there's already an active tracing relationship, then make an
+ * exception for the sake of other accesses, like process_vm_rw().
+ */
+ parent = ptrace_parent(tracee);
+ if (parent != NULL && same_thread_group(parent, tracer)) {
+ rc = 1;
+ goto unlock;
+ }
+
+ /* Look for a PR_SET_PTRACER relationship. */
if (!thread_group_leader(tracee))
tracee = rcu_dereference(tracee->group_leader);
list_for_each_entry_rcu(relation, &ptracer_relations, node) {
@@ -334,6 +346,8 @@ static int ptracer_exception_found(struct task_struct *tracer,
if (found && (parent == NULL || task_is_descendant(parent, tracer)))
rc = 1;
+
+unlock:
rcu_read_unlock();
return rc;