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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181// 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 50static 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;
argv[0] = modprobe_path; argv[1] = "-q"; argv[2] = "--"; argv[3] = module_name; /* check free_modprobe_argv() */ argv[4] = NULL;
info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL, NULL, free_modprobe_argv, NULL); if (!info) goto free_module_name;
ret = call_usermodehelper_exec(info, wait | UMH_KILLABLE); kmod_dup_request_announce(orig_module_name, ret); return ret;
free_module_name: kfree(module_name);free_argv: kfree(argv);out: kmod_dup_request_announce(orig_module_name, -ENOMEM); return -ENOMEM;}
/** * __request_module - try to load a kernel module * @wait: wait (or not) for the operation to complete * @fmt: printf style format string for the name of the module * @...: arguments as specified in the format string * * Load a module using the user mode module loader. The function returns * zero on success or a negative errno code or positive exit code from * "modprobe" on failure. Note that a successful module load does not mean * the module did not then unload and exit on an error of its own. Callers * must check that the service they requested is now available not blindly * invoke it. * * If module auto-loading support is disabled then this function * simply returns -ENOENT. */int __request_module(bool wait, const char *fmt, ...){ va_list args; char module_name[MODULE_NAME_LEN]; int ret, dup_ret;
/* * We don't allow synchronous module loading from async. Module * init may invoke async_synchronize_full() which will end up * waiting for this task which already is waiting for the module * loading to complete, leading to a deadlock. */ WARN_ON_ONCE(wait && current_is_async());
if (!modprobe_path[0]) return -ENOENT;
va_start(args, fmt); ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args); va_end(args); if (ret >= MODULE_NAME_LEN) return -ENAMETOOLONG;
ret = security_kernel_module_request(module_name); if (ret) return ret;
ret = down_timeout(&kmod_concurrent_max, MAX_KMOD_ALL_BUSY_TIMEOUT * HZ); if (ret) { pr_warn_ratelimited("request_module: modprobe %s cannot be processed, kmod busy with %d threads for more than %d seconds now", module_name, MAX_KMOD_CONCURRENT, MAX_KMOD_ALL_BUSY_TIMEOUT); return ret; }
trace_module_request(module_name, wait, _RET_IP_);
if (kmod_dup_request_exists_wait(module_name, wait, &dup_ret)) { ret = dup_ret; goto out; }
ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
out: up(&kmod_concurrent_max);
return ret;}EXPORT_SYMBOL(__request_module);