flask_op.c

xen 3.2.2 源码

/*
 *  This file contains the flask_op hypercall and associated functions.
 *
 *  Author:  George Coker, <[e-mail]>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2,
 *  as published by the Free Software Foundation.
 */

#include <xen/errno.h>
#include <xsm/xsm.h>
#include <xen/guest_access.h>

#include <public/xsm/flask_op.h>

#include <avc.h>
#include <avc_ss.h>
#include <objsec.h>
#include <conditional.h>

#ifdef FLASK_DEVELOP
int flask_enforcing = 0;
integer_param("flask_enforcing", flask_enforcing);
#endif

#ifdef FLASK_BOOTPARAM
int flask_enabled = 1;
integer_param("flask_enabled", flask_enabled);
#endif

static DEFINE_SPINLOCK(sel_sem);

/* global data for booleans */
static int bool_num = 0;
static int *bool_pending_values = NULL;

extern int ss_initialized;

extern struct xsm_operations *original_ops;

static int domain_has_security(struct domain *d, u32 perms)
{
    struct domain_security_struct *dsec;
    
    dsec = d->ssid;
    if ( !dsec )
        return -EACCES;
        
    return avc_has_perm(dsec->sid, SECINITSID_SECURITY, SECCLASS_SECURITY, 
                                                                perms, NULL);
}

static int flask_security_user(char *buf, int size)
{
    char *page = NULL;
    char *con, *user, *ptr;
    u32 sid, *sids;
    int length;
    char *newcon;
    int i, rc;
    u32 len, nsids;
        
    length = domain_has_security(current->domain, SECURITY__COMPUTE_USER);
    if ( length )
        return length;
            
    length = -ENOMEM;
    con = xmalloc_array(char, size+1);
    if ( !con )
        return length;
    memset(con, 0, size+1);
    
    user = xmalloc_array(char, size+1);
    if ( !user )
        goto out;
    memset(user, 0, size+1);
    
    length = -ENOMEM;
    page = xmalloc_bytes(PAGE_SIZE);
    if ( !page )
        goto out2;
    memset(page, 0, PAGE_SIZE);

    length = -EFAULT;
    if ( copy_from_user(page, buf, size) )
        goto out2;
        
    length = -EINVAL;
    if ( sscanf(page, "%s %s", con, user) != 2 )
        goto out2;

    length = security_context_to_sid(con, strlen(con)+1, &sid);
    if ( length < 0 )
        goto out2;
            
    length = security_get_user_sids(sid, user, &sids, &nsids);
    if ( length < 0 )
        goto out2;
    
    memset(page, 0, PAGE_SIZE);
    length = snprintf(page, PAGE_SIZE, "%u", nsids) + 1;
    ptr = page + length;
    for ( i = 0; i < nsids; i++ )
    {
        rc = security_sid_to_context(sids[i], &newcon, &len);
        if ( rc )
        {
            length = rc;
            goto out3;
        }
        if ( (length + len) >= PAGE_SIZE )
        {
            xfree(newcon);
            length = -ERANGE;
            goto out3;
        }
        memcpy(ptr, newcon, len);
        xfree(newcon);
        ptr += len;
        length += len;
    }
    
    if ( copy_to_user(buf, page, length) )
        length = -EFAULT;
        
out3:
    xfree(sids);
out2:
    if ( page )
        xfree(page);
    xfree(user);
out:
    xfree(con);
    return length;
}

static int flask_security_relabel(char *buf, int size)
{
    char *scon, *tcon;
    u32 ssid, tsid, newsid;
    u16 tclass;
    int length;
    char *newcon;
    u32 len;

    length = domain_has_security(current->domain, SECURITY__COMPUTE_RELABEL);
    if ( length )
        return length;
            
    length = -ENOMEM;
    scon = xmalloc_array(char, size+1);
    if ( !scon )
        return length;
    memset(scon, 0, size+1);
        
    tcon = xmalloc_array(char, size+1);
    if ( !tcon )
        goto out;
    memset(tcon, 0, size+1);
        
    length = -EINVAL;
    if ( sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3 )
        goto out2;
            
    length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
    if ( length < 0 )
        goto out2;
    length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
    if ( length < 0 )
        goto out2;
            
    length = security_change_sid(ssid, tsid, tclass, &newsid);
    if ( length < 0 )
        goto out2;
            
    length = security_sid_to_context(newsid, &newcon, &len);
    if ( length < 0 )
        goto out2;
            
    if ( len > PAGE_SIZE )
    {
        length = -ERANGE;
        goto out3;
    }
        
    if ( copy_to_user(buf, newcon, len) )
        len = -EFAULT;

    length = len;
        
out3:
    xfree(newcon);
out2:
    xfree(tcon);
out:
    xfree(scon);
    return length;
}

static int flask_security_create(char *buf, int size)
{
    char *scon, *tcon;
    u32 ssid, tsid, newsid;
    u16 tclass;
    int length;
    char *newcon;
    u32 len;

    length = domain_has_security(current->domain, SECURITY__COMPUTE_CREATE);
    if ( length )
        return length;

    length = -ENOMEM;
    scon = xmalloc_array(char, size+1);
    if ( !scon )
        return length;
    memset(scon, 0, size+1);

    tcon = xmalloc_array(char, size+1);
    if ( !tcon )
        goto out;
    memset(tcon, 0, size+1);

    length = -EINVAL;
    if ( sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3 )
        goto out2;

    length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
    if ( length < 0 )
        goto out2;

    length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
    if ( length < 0 )
        goto out2;

    length = security_transition_sid(ssid, tsid, tclass, &newsid);
    if ( length < 0 )
        goto out2;

    length = security_sid_to_context(newsid, &newcon, &len);
    if ( length < 0 )    
        goto out2;

    if ( len > PAGE_SIZE )
    {
        printk( "%s:  context size (%u) exceeds payload "
                "max\n", __FUNCTION__, len);
        length = -ERANGE;
        goto out3;
    }

    if ( copy_to_user(buf, newcon, len) )
        len = -EFAULT;

    length = len;
        
out3:
    xfree(newcon);
out2:
    xfree(tcon);
out:
    xfree(scon);
    return length;
}

static int flask_security_access(char *buf, int size)
{
    char *page = NULL;
    char *scon, *tcon;
    u32 ssid, tsid;
    u16 tclass;
    u32 req;
    struct av_decision avd;
    int length;

    length = domain_has_security(current->domain, SECURITY__COMPUTE_AV);
    if ( length )
        return length;

    length = -ENOMEM;
    scon = xmalloc_array(char, size+1);
    if (!scon)
        return length;
    memset(scon, 0, size+1);

    tcon = xmalloc_array(char, size+1);
    if ( !tcon )
        goto out;
    memset( tcon, 0, size+1 );

    length = -EINVAL;
    if (sscanf(buf, "%s %s %hu %x", scon, tcon, &tclass, &req) != 4)
        goto out2;

    length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
    if ( length < 0 )
        goto out2;

    length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
    if ( length < 0 )
        goto out2;

    length = security_compute_av(ssid, tsid, tclass, req, &avd);
    if ( length < 0 )
        goto out2;

    page = (char *)xmalloc_bytes(PAGE_SIZE);
    if ( !page )
    {
        length = -ENOMEM;
        goto out2;
    }

    memset(page, 0, PAGE_SIZE);

    length = snprintf(page, PAGE_SIZE, "%x %x %x %x %u", 
                                        avd.allowed, avd.decided,
                                        avd.auditallow, avd.auditdeny, 
                                        avd.seqno);
                
    if ( copy_to_user(buf, page, length) )
        length = -EFAULT;
        
out2:
    xfree(tcon);
out:
    xfree(scon);
    return length;
}

static int flask_security_member(char *buf, int size)
{
    char *scon, *tcon;
    u32 ssid, tsid, newsid;
    u16 tclass;
    int length;
    char *newcon;
    u32 len;

    length = domain_has_security(current->domain, SECURITY__COMPUTE_MEMBER);
    if ( length )
        return length;

    length = -ENOMEM;
    scon = xmalloc_array(char, size+1);
    if ( !scon )
        return length;
    memset(scon, 0, size+1);

    tcon = xmalloc_array(char, size+1);
    if ( !tcon )
        goto out;
    memset(tcon, 0, size+1);

    length = -EINVAL;
    if ( sscanf(buf, "%s, %s, %hu", scon, tcon, &tclass) != 3 )
        goto out2;

    length = security_context_to_sid(scon, strlen(scon)+1, &ssid);
    if ( length < 0 )
        goto out2;

    length = security_context_to_sid(tcon, strlen(tcon)+1, &tsid);
    if ( length < 0 )
        goto out2;

    length = security_member_sid(ssid, tsid, tclass, &newsid);
    if ( length < 0 )
        goto out2;

    length = security_sid_to_context(newsid, &newcon, &len);
    if ( length < 0 )
        goto out2;

    if ( len > PAGE_SIZE )
    {
        printk("%s:  context size (%u) exceeds payload "
                "max\n", __FUNCTION__, len);
        length = -ERANGE;
        goto out3;
    }

    if ( copy_to_user(buf, newcon, len) )
        len = -EFAULT;

    length = len;

out3:
    xfree(newcon);
out2:
    xfree(tcon);
out:
    xfree(scon);
    return length;
}

static int flask_security_setenforce(char *buf, int count)
{
    char *page = NULL;
    int length;
    int new_value;

    if ( count < 0 || count >= PAGE_SIZE )
        return -ENOMEM;

    page = (char *)xmalloc_bytes(PAGE_SIZE);
    if ( !page )
        return -ENOMEM;
    memset(page, 0, PAGE_SIZE);
    length = -EFAULT;
    if ( copy_from_user(page, buf, count) )
        goto out;

    length = -EINVAL;
    if ( sscanf(page, "%d", &new_value) != 1 )
        goto out;

    if ( new_value != flask_enforcing )
    {
        length = domain_has_security(current->domain, SECURITY__SETENFORCE);
        if ( length )
            goto out;
        flask_enforcing = new_value;
        if ( flask_enforcing )
            avc_ss_reset(0);
    }
    length = count;

out:
    xfree(page);
    return length;
}

static int flask_security_context(char *buf, int count)
{
    char *page = NULL;
    u32 sid;
    int length;

    length = domain_has_security(current->domain, SECURITY__CHECK_CONTEXT);
    if ( length )
        goto out;

    if ( count < 0 || count >= PAGE_SIZE )
        return -ENOMEM;

    page = (char *)xmalloc_bytes(PAGE_SIZE);
    if ( !page )
        return -ENOMEM;
    memset(page, 0, PAGE_SIZE);
    length = -EFAULT;
    if ( copy_from_user(page, buf, count) )
        goto out;

    length = security_context_to_sid(page, count, &sid);
    if ( length < 0 )
        goto out;

    memset(page, 0, PAGE_SIZE);
    length = snprintf(page, PAGE_SIZE, "%u", sid);

    if ( copy_to_user(buf, page, count) )
        length = -EFAULT;

out:
    xfree(page);
    return length;
}

static int flask_security_sid(char *buf, int count)
{
    char *page = NULL;
    char *context;
    u32 sid;
    u32 len;
    int length;

    length = domain_has_security(current->domain, SECURITY__CHECK_CONTEXT);
    if ( length )
        goto out;

    if ( count < 0 || count >= PAGE_SIZE )
        return -ENOMEM;

    page = (char *)xmalloc_bytes(PAGE_SIZE);
    if ( !page )
        return -ENOMEM;
    memset(page, 0, PAGE_SIZE);
    length = -EFAULT;
    if ( copy_from_user(page, buf, count) )
        goto out;

    if ( sscanf(page, "%u", &sid) != 1 )
        goto out;

    length = security_sid_to_context(sid, &context, &len);
    if ( length < 0 )
        goto out;

    if ( copy_to_user(buf, context, len) )
        length = -EFAULT;
    
    xfree(context);

out:
    xfree(page);
    return length;
}

int flask_disable(void)
{
    static int flask_disabled = 0;

    if ( ss_initialized )
    {
        /* Not permitted after initial policy load. */
        return -EINVAL;
    }

    if ( flask_disabled )
    {
        /* Only do this once. */
        return -EINVAL;
    }

    printk("Flask:  Disabled at runtime.\n");

    flask_disabled = 1;

    /* Reset xsm_ops to the original module. */
    xsm_ops = original_ops;

    return 0;
}

static int flask_security_disable(char *buf, int count)
{
    char *page = NULL;
    int length;