task_context.c

/*
 * Copyright (c) 2023 Cisco and/or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: MIT OR GPL-2.0-only
 *
 * Licensed under the MIT license <LICENSE.MIT or https://opensource.org/licenses/MIT> or the GPLv2 license
 * <LICENSE.GPL or https://opensource.org/license/gpl-2-0>, at your option. This file may not be copied,
 * modified, or distributed except according to those terms.
 */

#include <linux/uaccess.h>
#include <linux/file.h>
#include <linux/path.h>
#include <linux/dcache.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/nsproxy.h>
#include <linux/cgroup.h>
#include <linux/ipc_namespace.h>
#include <linux/pid_namespace.h>
#include <linux/time_namespace.h>
#include <net/net_namespace.h>
#include <linux/utsname.h>

#include "task_context.h"

struct mnt_namespace
{
    struct ns_common ns;
};

task_context *get_task_context(void)
{
    struct task_context *context = kmalloc(sizeof(struct task_context), GFP_KERNEL);

    strcpy(context->command_name, current->comm);
    context->command_path = get_current_proc_path(context->command_path_buffer, sizeof(context->command_path_buffer));
    current_uid_gid(&context->uid, &context->gid);
    context->pid = current->pid;

    // namespace ids
    context->namespace_ids.uts = current->nsproxy->uts_ns->ns.inum;
    context->namespace_ids.ipc = current->nsproxy->ipc_ns->ns.inum;
    context->namespace_ids.mnt = current->nsproxy->mnt_ns->ns.inum;
    context->namespace_ids.pid = current->nsproxy->pid_ns_for_children->ns.inum;
    context->namespace_ids.net = current->nsproxy->net_ns->ns.inum;
    context->namespace_ids.time = current->nsproxy->time_ns->ns.inum;
    context->namespace_ids.cgroup = current->nsproxy->cgroup_ns->ns.inum;

    struct css_set *cset = task_css_set(current);
    if (cset)
    {
        cgroup_path(cset->dfl_cgrp, context->cgroup_path, sizeof(context->cgroup_path));
    }

    return context;
}

void free_task_context(struct task_context *context)
{
    kfree(context);
}

char *get_current_proc_path(char *buf, int buflen)
{
    struct file *exe_file;
    char *result = ERR_PTR(-ENOENT);
    struct mm_struct *mm;

    mm = get_task_mm(current);
    if (!mm)
    {
        goto out;
    }
    exe_file = mm->exe_file;
    if (exe_file)
    {
        get_file(exe_file);
        path_get(&exe_file->f_path);
    }
    mmput(mm);
    if (exe_file)
    {
        result = d_path(&exe_file->f_path, buf, buflen);
        path_put(&exe_file->f_path);
        fput(exe_file);
    }

out:
    return result;
}