[PATCH ghak90 V7 06/21] audit: contid limit of 32k imposed to avoid DoS

[Richard Guy Briggs]

Set an arbitrary limit on the number of audit container identifiers to
limit abuse.

Signed-off-by: Richard Guy Briggs <r...@redhat.com>
---
 kernel/audit.c | 8 ++++++++
 kernel/audit.h | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/kernel/audit.c b/kernel/audit.c
index 53d13d638c63..329916534dd2 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -139,6 +139,7 @@ struct audit_net {
 struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
 /* Hash for contid-based rules */
 struct list_head audit_contid_hash[AUDIT_CONTID_BUCKETS];
+int audit_contid_count = 0;
 
 static struct kmem_cache *audit_buffer_cache;
 
@@ -2384,6 +2385,7 @@ void audit_cont_put(struct audit_cont *cont)
                put_task_struct(cont->owner);
                list_del_rcu(&cont->list);
                kfree_rcu(cont, rcu);
+               audit_contid_count--;
        }
 }
 
@@ -2456,6 +2458,11 @@ int audit_set_contid(struct task_struct *task, u64 
contid)
                                        goto conterror;
                                }
                        }
+               /* Set max contids */
+               if (audit_contid_count > AUDIT_CONTID_COUNT) {
+                       rc = -ENOSPC;
+                       goto conterror;
+               }
                if (!newcont) {
                        newcont = kmalloc(sizeof(struct audit_cont), 
GFP_ATOMIC);
                        if (newcont) {
@@ -2465,6 +2472,7 @@ int audit_set_contid(struct task_struct *task, u64 contid)
                                newcont->owner = current;
                                refcount_set(&newcont->refcount, 1);
                                list_add_rcu(&newcont->list, 
&audit_contid_hash[h]);
+                               audit_contid_count++;
                        } else {
                                rc = -ENOMEM;
                                goto conterror;
diff --git a/kernel/audit.h b/kernel/audit.h
index 162de8366b32..543f1334ba47 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -219,6 +219,10 @@ static inline int audit_hash_contid(u64 contid)
        return (contid & (AUDIT_CONTID_BUCKETS-1));
 }
 
+extern int audit_contid_count;
+
+#define AUDIT_CONTID_COUNT     1 << 16
+
 /* Indicates that audit should log the full pathname. */
 #define AUDIT_NAME_FULL -1
 
-- 
1.8.3.1