selinux: convert type_val_to_struct to flex_array

In rawhide type_val_to_struct will allocate 26848 bytes, an order 3
allocations.  While this hasn't been seen to fail it isn't outside the
realm of possibiliy on systems with severe memory fragmentation.  Convert
to flex_array so no allocation will ever be bigger than PAGE_SIZE.

Signed-off-by: Eric Paris <eparis@redhat.com>

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 6ad73e8..af41fdf 100644 (file)
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -307,7 +307,11 @@ static int type_index(void *key, void *datum, void *datap)
                    || typdatum->bounds > p->p_types.nprim)
                        return -EINVAL;
                p->p_type_val_to_name[typdatum->value - 1] = key;
-               p->type_val_to_struct[typdatum->value - 1] = typdatum;
+               /* this flex array was all preallocated, this cannot fail */
+               if (flex_array_put_ptr(p->type_val_to_struct_array,
+                                      typdatum->value - 1, typdatum,
+                                      GFP_KERNEL | __GFP_ZERO))
+                       BUG();
        }
 
        return 0;
@@ -484,11 +488,17 @@ static int policydb_index_others(struct policydb *p)
        if (!p->user_val_to_struct)
                goto out;
 
+       /* Yes, I want the sizeof the pointer, not the structure */
        rc = -ENOMEM;
-       p->type_val_to_struct =
-               kmalloc(p->p_types.nprim * sizeof(*(p->type_val_to_struct)),
-                       GFP_KERNEL);
-       if (!p->type_val_to_struct)
+       p->type_val_to_struct_array = flex_array_alloc(sizeof(struct type_datum *),
+                                                      p->p_types.nprim,
+                                                      GFP_KERNEL | __GFP_ZERO);
+       if (!p->type_val_to_struct_array)
+               goto out;
+
+       rc = flex_array_prealloc(p->type_val_to_struct_array, 0,
+                                p->p_types.nprim - 1, GFP_KERNEL | __GFP_ZERO);
+       if (rc)
                goto out;
 
        rc = -ENOMEM;
@@ -699,7 +709,8 @@ void policydb_destroy(struct policydb *p)
        kfree(p->class_val_to_struct);
        kfree(p->role_val_to_struct);
        kfree(p->user_val_to_struct);
-       kfree(p->type_val_to_struct);
+       if (p->type_val_to_struct_array)
+               flex_array_free(p->type_val_to_struct_array);
 
        avtab_destroy(&p->te_avtab);
 
@@ -1618,7 +1629,10 @@ static int type_bounds_sanity_check(void *key, void *datum, void *datap)
                        return -EINVAL;
                }
 
-               upper = p->type_val_to_struct[upper->bounds - 1];
+               upper = flex_array_get_ptr(p->type_val_to_struct_array,
+                                          upper->bounds - 1);
+               BUG_ON(!upper);
+
                if (upper->attribute) {
                        printk(KERN_ERR "SELinux: type %s: "
                               "bounded by attribute %s",

diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index 95d3d7d..9826a92 100644 (file)
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -217,7 +217,7 @@ struct policydb {
        struct class_datum **class_val_to_struct;
        struct role_datum **role_val_to_struct;
        struct user_datum **user_val_to_struct;
-       struct type_datum **type_val_to_struct;
+       struct flex_array *type_val_to_struct_array;
 
        /* type enforcement access vectors and transitions */
        struct avtab te_avtab;

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index ab6dbce..afcbc19 100644 (file)
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -530,12 +530,18 @@ static void type_attribute_bounds_av(struct context *scontext,
        struct context lo_scontext;
        struct context lo_tcontext;
        struct av_decision lo_avd;
-       struct type_datum *source
-               = policydb.type_val_to_struct[scontext->type - 1];
-       struct type_datum *target
-               = policydb.type_val_to_struct[tcontext->type - 1];
+       struct type_datum *source;
+       struct type_datum *target;
        u32 masked = 0;
 
+       source = flex_array_get_ptr(policydb.type_val_to_struct_array,
+                                   scontext->type - 1);
+       BUG_ON(!source);
+
+       target = flex_array_get_ptr(policydb.type_val_to_struct_array,
+                                   tcontext->type - 1);
+       BUG_ON(!target);
+
        if (source->bounds) {
                memset(&lo_avd, 0, sizeof(lo_avd));
 
@@ -828,7 +834,8 @@ int security_bounded_transition(u32 old_sid, u32 new_sid)
 
        index = new_context->type;
        while (true) {
-               type = policydb.type_val_to_struct[index - 1];
+               type = flex_array_get_ptr(policydb.type_val_to_struct_array,
+                                         index - 1);
                BUG_ON(!type);
 
                /* not bounded anymore */