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-rw-r--r--security/yama/yama_lsm.c88
1 files changed, 62 insertions, 26 deletions
diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 0e72239aeb05..23414b93771f 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -17,6 +17,7 @@
#include <linux/ptrace.h>
#include <linux/prctl.h>
#include <linux/ratelimit.h>
+#include <linux/workqueue.h>
#define YAMA_SCOPE_DISABLED 0
#define YAMA_SCOPE_RELATIONAL 1
@@ -29,12 +30,37 @@ static int ptrace_scope = YAMA_SCOPE_RELATIONAL;
struct ptrace_relation {
struct task_struct *tracer;
struct task_struct *tracee;
+ bool invalid;
struct list_head node;
+ struct rcu_head rcu;
};
static LIST_HEAD(ptracer_relations);
static DEFINE_SPINLOCK(ptracer_relations_lock);
+static void yama_relation_cleanup(struct work_struct *work);
+static DECLARE_WORK(yama_relation_work, yama_relation_cleanup);
+
+/**
+ * yama_relation_cleanup - remove invalid entries from the relation list
+ *
+ */
+static void yama_relation_cleanup(struct work_struct *work)
+{
+ struct ptrace_relation *relation;
+
+ spin_lock(&ptracer_relations_lock);
+ rcu_read_lock();
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid) {
+ list_del_rcu(&relation->node);
+ kfree_rcu(relation, rcu);
+ }
+ }
+ rcu_read_unlock();
+ spin_unlock(&ptracer_relations_lock);
+}
+
/**
* yama_ptracer_add - add/replace an exception for this tracer/tracee pair
* @tracer: the task_struct of the process doing the ptrace
@@ -48,32 +74,34 @@ static DEFINE_SPINLOCK(ptracer_relations_lock);
static int yama_ptracer_add(struct task_struct *tracer,
struct task_struct *tracee)
{
- int rc = 0;
- struct ptrace_relation *added;
- struct ptrace_relation *entry, *relation = NULL;
+ struct ptrace_relation *relation, *added;
added = kmalloc(sizeof(*added), GFP_KERNEL);
if (!added)
return -ENOMEM;
- spin_lock_bh(&ptracer_relations_lock);
- list_for_each_entry(entry, &ptracer_relations, node)
- if (entry->tracee == tracee) {
- relation = entry;
- break;
+ added->tracee = tracee;
+ added->tracer = tracer;
+ added->invalid = false;
+
+ spin_lock(&ptracer_relations_lock);
+ rcu_read_lock();
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid)
+ continue;
+ if (relation->tracee == tracee) {
+ list_replace_rcu(&relation->node, &added->node);
+ kfree_rcu(relation, rcu);
+ goto out;
}
- if (!relation) {
- relation = added;
- relation->tracee = tracee;
- list_add(&relation->node, &ptracer_relations);
}
- relation->tracer = tracer;
- spin_unlock_bh(&ptracer_relations_lock);
- if (added != relation)
- kfree(added);
+ list_add_rcu(&added->node, &ptracer_relations);
- return rc;
+out:
+ rcu_read_unlock();
+ spin_unlock(&ptracer_relations_lock);
+ return 0;
}
/**
@@ -84,16 +112,23 @@ static int yama_ptracer_add(struct task_struct *tracer,
static void yama_ptracer_del(struct task_struct *tracer,
struct task_struct *tracee)
{
- struct ptrace_relation *relation, *safe;
+ struct ptrace_relation *relation;
+ bool marked = false;
- spin_lock_bh(&ptracer_relations_lock);
- list_for_each_entry_safe(relation, safe, &ptracer_relations, node)
+ rcu_read_lock();
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid)
+ continue;
if (relation->tracee == tracee ||
(tracer && relation->tracer == tracer)) {
- list_del(&relation->node);
- kfree(relation);
+ relation->invalid = true;
+ marked = true;
}
- spin_unlock_bh(&ptracer_relations_lock);
+ }
+ rcu_read_unlock();
+
+ if (marked)
+ schedule_work(&yama_relation_work);
}
/**
@@ -217,21 +252,22 @@ static int ptracer_exception_found(struct task_struct *tracer,
struct task_struct *parent = NULL;
bool found = false;
- spin_lock_bh(&ptracer_relations_lock);
rcu_read_lock();
if (!thread_group_leader(tracee))
tracee = rcu_dereference(tracee->group_leader);
- list_for_each_entry(relation, &ptracer_relations, node)
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid)
+ continue;
if (relation->tracee == tracee) {
parent = relation->tracer;
found = true;
break;
}
+ }
if (found && (parent == NULL || task_is_descendant(parent, tracer)))
rc = 1;
rcu_read_unlock();
- spin_unlock_bh(&ptracer_relations_lock);
return rc;
}