resource.c

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/*
 * AppArmor security module
 *
 * This file contains AppArmor resource mediation and attachment
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 *
 * 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 of the
 * License.
 */

#include <linux/audit.h>

#include "include/audit.h"
#include "include/resource.h"
#include "include/policy.h"

/*
 * Table of rlimit names: we generate it from resource.h.
 */
#include "rlim_names.h"

struct aa_fs_entry aa_fs_entry_rlimit[] = {
    AA_FS_FILE_STRING("mask", AA_FS_RLIMIT_MASK),
    { }
};

/* audit callback for resource specific fields */
static void audit_cb(struct audit_buffer *ab, void *va)
{
    struct common_audit_data *sa = va;

    audit_log_format(ab, " rlimit=%s value=%lu",
             rlim_names[sa->aad->rlim.rlim], sa->aad->rlim.max);
}

static int audit_resource(struct aa_profile *profile, unsigned int resource,
              unsigned long value, int error)
{
    struct common_audit_data sa;
    struct apparmor_audit_data aad = {0,};

    sa.type = LSM_AUDIT_DATA_NONE;
    sa.aad = &aad;
    aad.op = OP_SETRLIMIT,
    aad.rlim.rlim = resource;
    aad.rlim.max = value;
    aad.error = error;
    return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_KERNEL, &sa,
            audit_cb);
}

int aa_map_resource(int resource)
{
    return rlim_map[resource];
}

int aa_task_setrlimit(struct aa_profile *profile, struct task_struct *task,
              unsigned int resource, struct rlimit *new_rlim)
{
    int error = 0;

    /* TODO: extend resource control to handle other (non current)
     * processes.  AppArmor rules currently have the implicit assumption
     * that the task is setting the resource of the current process
     */
    if ((task != current->group_leader) ||
        (profile->rlimits.mask & (1 << resource) &&
         new_rlim->rlim_max > profile->rlimits.limits[resource].rlim_max))
        error = -EACCES;

    return audit_resource(profile, resource, new_rlim->rlim_max, error);
}

void __aa_transition_rlimits(struct aa_profile *old, struct aa_profile *new)
{
    unsigned int mask = 0;
    struct rlimit *rlim, *initrlim;
    int i;

    /* for any rlimits the profile controlled reset the soft limit
     * to the less of the tasks hard limit and the init tasks soft limit
     */
    if (old->rlimits.mask) {
        for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
            if (old->rlimits.mask & mask) {
                rlim = current->signal->rlim + i;
                initrlim = init_task.signal->rlim + i;
                rlim->rlim_cur = min(rlim->rlim_max,
                             initrlim->rlim_cur);
            }
        }
    }

    /* set any new hard limits as dictated by the new profile */
    if (!new->rlimits.mask)
        return;
    for (i = 0, mask = 1; i < RLIM_NLIMITS; i++, mask <<= 1) {
        if (!(new->rlimits.mask & mask))
            continue;

        rlim = current->signal->rlim + i;
        rlim->rlim_max = min(rlim->rlim_max,
                     new->rlimits.limits[i].rlim_max);
        /* soft limit should not exceed hard limit */
        rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
    }
}