capability.c

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/*
 * AppArmor security module
 *
 * This file contains AppArmor capability mediation functions
 *
 * 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/capability.h>
#include <linux/errno.h>
#include <linux/gfp.h>

#include "include/apparmor.h"
#include "include/capability.h"
#include "include/context.h"
#include "include/policy.h"
#include "include/audit.h"

/*
 * Table of capability names: we generate it from capabilities.h.
 */
#include "capability_names.h"

struct audit_cache {
    struct aa_profile *profile;
    kernel_cap_t caps;
};

static DEFINE_PER_CPU(struct audit_cache, audit_cache);

static void audit_cb(struct audit_buffer *ab, void *va)
{
    struct common_audit_data *sa = va;
    audit_log_format(ab, " capname=");
    audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
}

static int audit_caps(struct aa_profile *profile, struct task_struct *task,
              int cap, int error)
{
    struct audit_cache *ent;
    int type = AUDIT_APPARMOR_AUTO;
    struct common_audit_data sa;
    struct apparmor_audit_data aad = {0,};
    sa.type = LSM_AUDIT_DATA_CAP;
    sa.aad = &aad;
    sa.u.cap = cap;
    sa.aad->tsk = task;
    sa.aad->op = OP_CAPABLE;
    sa.aad->error = error;

    if (likely(!error)) {
        /* test if auditing is being forced */
        if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
               !cap_raised(profile->caps.audit, cap)))
            return 0;
        type = AUDIT_APPARMOR_AUDIT;
    } else if (KILL_MODE(profile) ||
           cap_raised(profile->caps.kill, cap)) {
        type = AUDIT_APPARMOR_KILL;
    } else if (cap_raised(profile->caps.quiet, cap) &&
           AUDIT_MODE(profile) != AUDIT_NOQUIET &&
           AUDIT_MODE(profile) != AUDIT_ALL) {
        /* quiet auditing */
        return error;
    }

    /* Do simple duplicate message elimination */
    ent = &get_cpu_var(audit_cache);
    if (profile == ent->profile && cap_raised(ent->caps, cap)) {
        put_cpu_var(audit_cache);
        if (COMPLAIN_MODE(profile))
            return complain_error(error);
        return error;
    } else {
        aa_put_profile(ent->profile);
        ent->profile = aa_get_profile(profile);
        cap_raise(ent->caps, cap);
    }
    put_cpu_var(audit_cache);

    return aa_audit(type, profile, GFP_ATOMIC, &sa, audit_cb);
}

static int profile_capable(struct aa_profile *profile, int cap)
{
    return cap_raised(profile->caps.allow, cap) ? 0 : -EPERM;
}

int aa_capable(struct task_struct *task, struct aa_profile *profile, int cap,
           int audit)
{
    int error = profile_capable(profile, cap);

    if (!audit) {
        if (COMPLAIN_MODE(profile))
            return complain_error(error);
        return error;
    }

    return audit_caps(profile, task, cap, error);
}