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/*
* Copyright (C) 2010-2025 Red Hat, Inc. All rights reserved.
*
* Author: Fabio M. Di Nitto <fabbione@kronosnet.org>
*
* This software licensed under LGPL-2.0+
*/
#include "config.h"
#include <unistd.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <errno.h>
#include <libgen.h>
#include <link.h>
#include <string.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include "logging.h"
#include "common.h"
int _fdset_cloexec(int fd)
{
int fdflags;
fdflags = fcntl(fd, F_GETFD, 0);
if (fdflags < 0)
return -1;
fdflags |= FD_CLOEXEC;
if (fcntl(fd, F_SETFD, fdflags) < 0)
return -1;
return 0;
}
int _fdset_nonblock(int fd)
{
int fdflags;
fdflags = fcntl(fd, F_GETFL, 0);
if (fdflags < 0)
return -1;
fdflags |= O_NONBLOCK;
if (fcntl(fd, F_SETFL, fdflags) < 0)
return -1;
return 0;
}
static int get_lib_dir(void *lib_handle, char dir[MAXPATHLEN])
{
int res;
#ifndef HAVE_RTLD_DI_ORIGIN
struct link_map *lm;
char l_name[MAXPATHLEN];
#endif
#ifdef HAVE_RTLD_DI_ORIGIN
res = dlinfo(lib_handle, RTLD_DI_ORIGIN, dir);
#else
/*
* musl libc doesn't support RTLD_DI_ORIGIN
*/
res = dlinfo(lib_handle, RTLD_DI_LINKMAP, &lm);
if (res == 0) {
snprintf(l_name, sizeof(l_name), "%s", lm->l_name);
snprintf(dir, MAXPATHLEN, "%s", dirname(l_name));
}
#endif
return res;
}
static void *open_lib(knet_handle_t knet_h, const char *libname, int extra_flags)
{
void *ret = NULL;
char *error = NULL;
char dir[MAXPATHLEN], path[MAXPATHLEN * 2], link[MAXPATHLEN];
struct stat sb;
/*
* clear any pending error
*/
dlerror();
strncpy(path, knet_h->plugin_path, sizeof(path)-1);
strncat(path, "/", sizeof(path)-1);
strncat(path, libname, sizeof(path)-strlen(knet_h->plugin_path)-2);
ret = dlopen(path, RTLD_NOW | RTLD_GLOBAL | extra_flags);
if (!ret) {
error = dlerror();
if (error) {
log_err(knet_h, KNET_SUB_COMMON, "unable to dlopen %s: %s", libname, error);
} else {
log_err(knet_h, KNET_SUB_COMMON, "unable to dlopen %s: unknown error", libname);
}
errno = EAGAIN;
return NULL;
}
memset(dir, 0, sizeof(dir));
memset(link, 0, sizeof(link));
memset(path, 0, sizeof(path));
if (get_lib_dir(ret, dir) < 0) {
/*
* should we dlclose and return error?
*/
error = dlerror();
log_warn(knet_h, KNET_SUB_COMMON, "unable to dlinfo %s: %s",
libname, error);
} else {
snprintf(path, sizeof(path), "%s/%s", dir, libname);
log_info(knet_h, KNET_SUB_COMMON, "%s has been loaded from %s", libname, path);
/*
* try to resolve the library and check if it is a symlink and to where.
* we can't prevent symlink attacks but at least we can log where the library
* has been loaded from
*/
if (lstat(path, &sb) < 0) {
log_debug(knet_h, KNET_SUB_COMMON, "Unable to stat %s: %s", path, strerror(errno));
goto out;
}
if (S_ISLNK(sb.st_mode)) {
if (readlink(path, link, sizeof(link)-1) < 0) {
log_debug(knet_h, KNET_SUB_COMMON, "Unable to readlink %s: %s", path, strerror(errno));
goto out;
}
link[sizeof(link) - 1] = 0;
/*
* symlink is relative to the directory
*/
if (link[0] != '/') {
snprintf(path, sizeof(path), "%s/%s", dir, link);
log_info(knet_h, KNET_SUB_COMMON, "%s/%s is a symlink to %s", dir, libname, path);
} else {
log_info(knet_h, KNET_SUB_COMMON, "%s/%s is a symlink to %s", dir, libname, link);
}
}
}
out:
return ret;
}
void *load_module(knet_handle_t knet_h, const char *type, const char *name)
{
void *module, *ops;
log_msg_t **log_msg_sym;
char soname[MAXPATHLEN], opsname[MAXPATHLEN];
snprintf (soname, sizeof soname, "%s_%s.so", type, name);
module = open_lib(knet_h, soname, 0);
if (!module) {
return NULL;
}
log_msg_sym = dlsym (module, "log_msg");
if (!log_msg_sym) {
log_err (knet_h, KNET_SUB_COMMON, "unable to map symbol 'log_msg' in module %s: %s",
soname, dlerror ());
errno = EINVAL;
return NULL;
}
*log_msg_sym = log_msg;
snprintf (opsname, sizeof opsname, "%s_model", type);
ops = dlsym (module, opsname);
if (!ops) {
log_err (knet_h, KNET_SUB_COMMON, "unable to map symbol 'model' in module %s: %s",
soname, dlerror ());
errno = EINVAL;
return NULL;
}
return ops;
}
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