kernel/module/kmod.c

Source file repositories/reference/linux-study-clean/kernel/module/kmod.c

File Facts

System
Linux kernel
Corpus path
kernel/module/kmod.c
Extension
.c
Size
4916 bytes
Lines
181
Domain
Core OS
Bucket
Scheduler, Processes, Timers, Sync, And Syscalls
Inferred role
Core OS: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * kmod - the kernel module loader
 *
 * Copyright (C) 2023 Luis Chamberlain <mcgrof@kernel.org>
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/binfmts.h>
#include <linux/syscalls.h>
#include <linux/unistd.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/completion.h>
#include <linux/cred.h>
#include <linux/file.h>
#include <linux/workqueue.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/resource.h>
#include <linux/notifier.h>
#include <linux/suspend.h>
#include <linux/rwsem.h>
#include <linux/ptrace.h>
#include <linux/async.h>
#include <linux/uaccess.h>

#include <trace/events/module.h>
#include "internal.h"

/*
 * Assuming:
 *
 * threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
 *		       (u64) THREAD_SIZE * 8UL);
 *
 * If you need less than 50 threads would mean we're dealing with systems
 * smaller than 3200 pages. This assumes you are capable of having ~13M memory,
 * and this would only be an upper limit, after which the OOM killer would take
 * effect. Systems like these are very unlikely if modules are enabled.
 */
#define MAX_KMOD_CONCURRENT 50
static DEFINE_SEMAPHORE(kmod_concurrent_max, MAX_KMOD_CONCURRENT);

/*
 * This is a restriction on having *all* MAX_KMOD_CONCURRENT threads
 * running at the same time without returning. When this happens we
 * believe you've somehow ended up with a recursive module dependency
 * creating a loop.
 *
 * We have no option but to fail.
 *
 * Userspace should proactively try to detect and prevent these.
 */
#define MAX_KMOD_ALL_BUSY_TIMEOUT 5

/*
	modprobe_path is set via /proc/sys.
*/
char modprobe_path[KMOD_PATH_LEN] = CONFIG_MODPROBE_PATH;

static void free_modprobe_argv(struct subprocess_info *info)
{
	kfree(info->argv[3]); /* check call_modprobe() */
	kfree(info->argv);
}

static int call_modprobe(char *orig_module_name, int wait)
{
	struct subprocess_info *info;
	static char *envp[] = {
		"HOME=/",
		"TERM=linux",
		"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
		NULL
	};
	char *module_name;
	int ret;

	char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
	if (!argv)
		goto out;

	module_name = kstrdup(orig_module_name, GFP_KERNEL);
	if (!module_name)
		goto free_argv;

Annotation

Implementation Notes