avtab.c

xen 3.2.2 源码

/*
 * Implementation of the access vector table type.
 *
 * Author : Stephen Smalley, <[e-mail]>
 */

/* Updated: Frank Mayer <[e-mail]> and Karl MacMillan <[e-mail]>
 *
 *     Added conditional policy language extensions
 *
 * Copyright (C) 2003 Tresys Technology, LLC
 *    This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation, version 2.
 */

/* Ported to Xen 3.0, George Coker, <[e-mail]> */

#include <xen/lib.h>
#include <asm/byteorder.h>
#include <xen/types.h>
#include <xen/xmalloc.h>
#include <xen/errno.h>

#include "avtab.h"
#include "policydb.h"

#define AVTAB_HASH(keyp) \
((keyp->target_class + \
 (keyp->target_type << 2) + \
 (keyp->source_type << 9)) & \
 AVTAB_HASH_MASK)

static struct avtab_node* avtab_insert_node(struct avtab *h, int hvalue,
    struct avtab_node * prev, struct avtab_node * cur, struct avtab_key *key, 
                                                    struct avtab_datum *datum)
{
    struct avtab_node * newnode;
    newnode = xmalloc(struct avtab_node);
    if ( newnode == NULL )
        return NULL;
    memset(newnode, 0, sizeof(struct avtab_node));
    newnode->key = *key;
    newnode->datum = *datum;
    if ( prev )
    {
        newnode->next = prev->next;
        prev->next = newnode;
    }
    else
    {
        newnode->next = h->htable[hvalue];
        h->htable[hvalue] = newnode;
    }

    h->nel++;
    return newnode;
}

static int avtab_insert(struct avtab *h, struct avtab_key *key, 
                                                    struct avtab_datum *datum)
{
    int hvalue;
    struct avtab_node *prev, *cur, *newnode;
    u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

    if ( !h )
        return -EINVAL;

    hvalue = AVTAB_HASH(key);
    for ( prev = NULL, cur = h->htable[hvalue]; cur;
                                                    prev = cur, cur = cur->next)
    {
        if ( key->source_type == cur->key.source_type &&
                                key->target_type == cur->key.target_type &&
                                key->target_class == cur->key.target_class &&
                                            (specified & cur->key.specified) )
            return -EEXIST;
        if ( key->source_type < cur->key.source_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                    key->target_type < cur->key.target_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                    key->target_type == cur->key.target_type &&
                                    key->target_class < cur->key.target_class )
            break;
    }

    newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);
    if( !newnode )
        return -ENOMEM;

    return 0;
}

/* Unlike avtab_insert(), this function allow multiple insertions of the same
 * key/specified mask into the table, as needed by the conditional avtab.
 * It also returns a pointer to the node inserted.
 */
struct avtab_node * avtab_insert_nonunique(struct avtab * h, 
                            struct avtab_key * key, struct avtab_datum * datum)
{
    int hvalue;
    struct avtab_node *prev, *cur, *newnode;
    u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

    if ( !h )
        return NULL;
    hvalue = AVTAB_HASH(key);
    for ( prev = NULL, cur = h->htable[hvalue]; cur; 
                                                prev = cur, cur = cur->next )
    {
        if ( key->source_type == cur->key.source_type &&
                                key->target_type == cur->key.target_type &&
                                key->target_class == cur->key.target_class &&
                                            (specified & cur->key.specified) )
            break;
        if ( key->source_type < cur->key.source_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                    key->target_type < cur->key.target_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                key->target_type == cur->key.target_type &&
                                key->target_class < cur->key.target_class )
            break;
    }
    newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);

    return newnode;
}

struct avtab_datum *avtab_search(struct avtab *h, struct avtab_key *key)
{
    int hvalue;
    struct avtab_node *cur;
    u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

    if ( !h )
        return NULL;

    hvalue = AVTAB_HASH(key);
    for ( cur = h->htable[hvalue]; cur; cur = cur->next )
    {
        if ( key->source_type == cur->key.source_type &&
                                key->target_type == cur->key.target_type &&
                                key->target_class == cur->key.target_class &&
                                            (specified & cur->key.specified) )
            return &cur->datum;

        if ( key->source_type < cur->key.source_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                    key->target_type < cur->key.target_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                key->target_type == cur->key.target_type &&
                                key->target_class < cur->key.target_class )
            break;
    }

    return NULL;
}

/* This search function returns a node pointer, and can be used in
 * conjunction with avtab_search_next_node()
 */
struct avtab_node* avtab_search_node(struct avtab *h, struct avtab_key *key)
{
    int hvalue;
    struct avtab_node *cur;
    u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

    if ( !h )
        return NULL;

    hvalue = AVTAB_HASH(key);
    for ( cur = h->htable[hvalue]; cur; cur = cur->next )
    {
        if ( key->source_type == cur->key.source_type &&
                                key->target_type == cur->key.target_type &&
                                key->target_class == cur->key.target_class &&
                                            (specified & cur->key.specified) )
            return cur;

        if ( key->source_type < cur->key.source_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                    key->target_type < cur->key.target_type )
            break;
        if ( key->source_type == cur->key.source_type &&
                                    key->target_type == cur->key.target_type &&
                                    key->target_class < cur->key.target_class )
            break;
    }
    return NULL;
}

struct avtab_node* avtab_search_node_next(struct avtab_node *node, 
                                                                int specified)
{
    struct avtab_node *cur;

    if ( !node )
        return NULL;

    specified &= ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
    for ( cur = node->next; cur; cur = cur->next )
    {
        if ( node->key.source_type == cur->key.source_type &&
                            node->key.target_type == cur->key.target_type &&
                            node->key.target_class == cur->key.target_class &&
                                            (specified & cur->key.specified) )
            return cur;

        if ( node->key.source_type < cur->key.source_type )
            break;
        if ( node->key.source_type == cur->key.source_type &&
                                node->key.target_type < cur->key.target_type )
            break;
        if ( node->key.source_type == cur->key.source_type &&
                            node->key.target_type == cur->key.target_type &&
                            node->key.target_class < cur->key.target_class )
            break;
    }
    return NULL;
}

void avtab_destroy(struct avtab *h)
{
    int i;
    struct avtab_node *cur, *temp;

    if ( !h || !h->htable )
        return;

    for ( i = 0; i < AVTAB_SIZE; i++ )
    {
        cur = h->htable[i];
        while ( cur != NULL )
        {
            temp = cur;
            cur = cur->next;
            xfree(temp);
        }
        h->htable[i] = NULL;
    }
    xfree(h->htable);
    h->htable = NULL;
}


int avtab_init(struct avtab *h)
{
    int i;

    h->htable = (void *)xmalloc_array(struct avtab_node, AVTAB_SIZE);
    if ( !h->htable )
        return -ENOMEM;
    for ( i = 0; i < AVTAB_SIZE; i++ )
        h->htable[i] = NULL;
    h->nel = 0;
    return 0;
}

void avtab_hash_eval(struct avtab *h, char *tag)
{
    int i, chain_len, slots_used, max_chain_len;
    struct avtab_node *cur;

    slots_used = 0;
    max_chain_len = 0;
    for ( i = 0; i < AVTAB_SIZE; i++ )
    {
        cur = h->htable[i];
        if ( cur )
        {
            slots_used++;
            chain_len = 0;
            while ( cur )
            {
                chain_len++;
                cur = cur->next;
            }

            if ( chain_len > max_chain_len )
                max_chain_len = chain_len;
        }
    }

    printk(KERN_INFO "%s:  %d entries and %d/%d buckets used, longest "
           "chain length %d\n", tag, h->nel, slots_used, AVTAB_SIZE,
                                                               max_chain_len);
}

static uint16_t spec_order[] = {
    AVTAB_ALLOWED,
    AVTAB_AUDITDENY,
    AVTAB_AUDITALLOW,
    AVTAB_TRANSITION,
    AVTAB_CHANGE,
    AVTAB_MEMBER
};

int avtab_read_item(void *fp, u32 vers, struct avtab *a,
                            int (*insertf)(struct avtab *a, struct avtab_key *k,
                                    struct avtab_datum *d, void *p), void *p)
{
    __le16 buf16[4];
    u16 enabled;
    __le32 buf32[7];
    u32 items, items2, val;
    struct avtab_key key;
    struct avtab_datum datum;
    int i, rc;

    memset(&key, 0, sizeof(struct avtab_key));
    memset(&datum, 0, sizeof(struct avtab_datum));

    if ( vers < POLICYDB_VERSION_AVTAB )
    {
        rc = next_entry(buf32, fp, sizeof(u32));
        if ( rc < 0 )
        {
            printk(KERN_ERR "security: avtab: truncated entry\n");
            return -1;
        }
        items2 = le32_to_cpu(buf32[0]);
        if ( items2 > ARRAY_SIZE(buf32) )
        {
            printk(KERN_ERR "security: avtab: entry overflow\n");
            return -1;

        }
        rc = next_entry(buf32, fp, sizeof(u32)*items2);
        if ( rc < 0 )
        {
            printk(KERN_ERR "security: avtab: truncated entry\n");
            return -1;
        }
        items = 0;

        val = le32_to_cpu(buf32[items++]);
        key.source_type = (u16)val;
        if ( key.source_type != val )
        {
            printk("security: avtab: truncated source type\n");
            return -1;
        }
        val = le32_to_cpu(buf32[items++]);
        key.target_type = (u16)val;
        if ( key.target_type != val )
        {
            printk("security: avtab: truncated target type\n");
            return -1;
        }
        val = le32_to_cpu(buf32[items++]);
        key.target_class = (u16)val;
        if ( key.target_class != val )
        {
            printk("security: avtab: truncated target class\n");
            return -1;
        }

        val = le32_to_cpu(buf32[items++]);
        enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;

        if ( !(val & (AVTAB_AV | AVTAB_TYPE)) )
        {
            printk("security: avtab: null entry\n");
            return -1;
        }
        if ( (val & AVTAB_AV) && (val & AVTAB_TYPE) )
        {
            printk("security: avtab: entry has both access vectors and types\n");
            return -1;
        }

        for ( i = 0; i < sizeof(spec_order)/sizeof(u16); i++ )
        {
            if ( val & spec_order[i] )
            {
                key.specified = spec_order[i] | enabled;
                datum.data = le32_to_cpu(buf32[items++]);
                rc = insertf(a, &key, &datum, p);
                if ( rc )
                    return rc;
            }
        }

        if ( items != items2 ) {
            printk("security: avtab: entry only had %d items, expected %d\n", 
                                                                items2, items);
            return -1;
        }
        return 0;
    }

    rc = next_entry(buf16, fp, sizeof(u16)*4);
    if ( rc < 0 )
    {
        printk("security: avtab: truncated entry\n");
        return -1;
    }

    items = 0;
    key.source_type = le16_to_cpu(buf16[items++]);
    key.target_type = le16_to_cpu(buf16[items++]);
    key.target_class = le16_to_cpu(buf16[items++]);
    key.specified = le16_to_cpu(buf16[items++]);

    rc = next_entry(buf32, fp, sizeof(u32));
    if ( rc < 0 )
    {
        printk("security: avtab: truncated entry\n");
        return -1;
    }
    datum.data = le32_to_cpu(*buf32);
    return insertf(a, &key, &datum, p);
}

static int avtab_insertf(struct avtab *a, struct avtab_key *k,
                                                struct avtab_datum *d, void *p)
{
    return avtab_insert(a, k, d);
}

int avtab_read(struct avtab *a, void *fp, u32 vers)
{
    int rc;
    __le32 buf[1];
    u32 nel, i;

    rc = next_entry(buf, fp, sizeof(u32));
    if ( rc < 0 )
    {
        printk(KERN_ERR "security: avtab: truncated table\n");
        goto bad;
    }
    nel = le32_to_cpu(buf[0]);
    if ( !nel )
    {
        printk(KERN_ERR "security: avtab: table is empty\n");
        rc = -EINVAL;
        goto bad;
    }
    for ( i = 0; i < nel; i++ )
    {
        rc = avtab_read_item(fp,vers, a, avtab_insertf, NULL);
        if ( rc )
        {
            if ( rc == -ENOMEM )
                printk(KERN_ERR "security: avtab: out of memory\n");
            else if ( rc == -EEXIST )
                printk(KERN_ERR "security: avtab: duplicate entry\n");
            else
                rc = -EINVAL;
            goto bad;
        }
    }

    rc = 0;
out:
    return rc;

bad:
    avtab_destroy(a);
    goto out;
}