ipc.c

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/*
 * AppArmor security module
 *
 * This file contains AppArmor ipc mediation
 *
 * 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/gfp.h>
#include <linux/ptrace.h>

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

/* call back to audit ptrace fields */
static void audit_cb(struct audit_buffer *ab, void *va)
{
    struct common_audit_data *sa = va;
    audit_log_format(ab, " target=");
    audit_log_untrustedstring(ab, sa->aad->target);
}

static int aa_audit_ptrace(struct aa_profile *profile,
               struct aa_profile *target, 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_PTRACE;
    aad.target = target;
    aad.error = error;

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

int aa_may_ptrace(struct task_struct *tracer_task, struct aa_profile *tracer,
          struct aa_profile *tracee, unsigned int mode)
{
    /* TODO: currently only based on capability, not extended ptrace
     *       rules,
     *       Test mode for PTRACE_MODE_READ || PTRACE_MODE_ATTACH
     */

    if (unconfined(tracer) || tracer == tracee)
        return 0;
    /* log this capability request */
    return aa_capable(tracer_task, tracer, CAP_SYS_PTRACE, 1);
}

int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
          unsigned int mode)
{
    /*
     * tracer can ptrace tracee when
     * - tracer is unconfined ||
     *   - tracer is in complain mode
     *   - tracer has rules allowing it to trace tracee currently this is:
     *       - confined by the same profile ||
     *       - tracer profile has CAP_SYS_PTRACE
     */

    struct aa_profile *tracer_p;
    /* cred released below */
    const struct cred *cred = get_task_cred(tracer);
    int error = 0;
    tracer_p = aa_cred_profile(cred);

    if (!unconfined(tracer_p)) {
        /* lcred released below */
        const struct cred *lcred = get_task_cred(tracee);
        struct aa_profile *tracee_p = aa_cred_profile(lcred);

        error = aa_may_ptrace(tracer, tracer_p, tracee_p, mode);
        error = aa_audit_ptrace(tracer_p, tracee_p, error);

        put_cred(lcred);
    }
    put_cred(cred);

    return error;
}