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Yama features for 3.8: 

- replacing locks with RCU
 - replacing in-place delete with workqueue
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 Version: GnuPG v1.4.11 (GNU/Linux)
 Comment: Kees Cook <kees@outflux.net>
 
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Merge tag 'yama-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into next

Yama features for 3.8:
- replacing locks with RCU
- replacing in-place delete with workqueue

Merged per request by Kees Cook.
This commit is contained in:
James Morris 2012-11-21 21:45:55 +11:00
parent b566650270 235e752789
commit 3f0cc6ae86
1 changed files with 62 additions and 26 deletions
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88
security/yama/yama_lsm.c
View File

@ -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;
}