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// SPDX-License-Identifier: GPL-3.0-or-later
#include "libnetdata/libnetdata.h"
#ifdef HAVE_SETNS
#ifndef _GNU_SOURCE
#define _GNU_SOURCE /* See feature_test_macros(7) */
#endif
#include <sched.h>
#endif
char environment_variable2[FILENAME_MAX + 50] = "";
char *environment[] = {
"PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin",
environment_variable2,
NULL
};
// ----------------------------------------------------------------------------
// callback required by fatal()
void netdata_cleanup_and_exit(int ret) {
exit(ret);
}
void send_statistics( const char *action, const char *action_result, const char *action_data) {
(void) action;
(void) action_result;
(void) action_data;
return;
}
// callbacks required by popen()
void signals_block(void) {};
void signals_unblock(void) {};
void signals_reset(void) {};
// callback required by eval()
int health_variable_lookup(const char *variable, uint32_t hash, struct rrdcalc *rc, calculated_number *result) {
(void)variable;
(void)hash;
(void)rc;
(void)result;
return 0;
};
// required by get_system_cpus()
char *netdata_configured_host_prefix = "";
// ----------------------------------------------------------------------------
struct iface {
const char *device;
uint32_t hash;
unsigned int ifindex;
unsigned int iflink;
struct iface *next;
};
unsigned int read_iface_iflink(const char *prefix, const char *iface) {
if(!prefix) prefix = "";
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s/sys/class/net/%s/iflink", prefix, iface);
unsigned long long iflink = 0;
int ret = read_single_number_file(filename, &iflink);
if(ret) error("Cannot read '%s'.", filename);
return (unsigned int)iflink;
}
unsigned int read_iface_ifindex(const char *prefix, const char *iface) {
if(!prefix) prefix = "";
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s/sys/class/net/%s/ifindex", prefix, iface);
unsigned long long ifindex = 0;
int ret = read_single_number_file(filename, &ifindex);
if(ret) error("Cannot read '%s'.", filename);
return (unsigned int)ifindex;
}
struct iface *read_proc_net_dev(const char *scope __maybe_unused, const char *prefix) {
if(!prefix) prefix = "";
procfile *ff = NULL;
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s%s", prefix, (*prefix)?"/proc/1/net/dev":"/proc/net/dev");
#ifdef NETDATA_INTERNAL_CHECKS
info("parsing '%s'", filename);
#endif
ff = procfile_open(filename, " \t,:|", PROCFILE_FLAG_DEFAULT);
if(unlikely(!ff)) {
error("Cannot open file '%s'", filename);
return NULL;
}
ff = procfile_readall(ff);
if(unlikely(!ff)) {
error("Cannot read file '%s'", filename);
return NULL;
}
size_t lines = procfile_lines(ff), l;
struct iface *root = NULL;
for(l = 2; l < lines ;l++) {
if (unlikely(procfile_linewords(ff, l) < 1)) continue;
struct iface *t = callocz(1, sizeof(struct iface));
t->device = strdupz(procfile_lineword(ff, l, 0));
t->hash = simple_hash(t->device);
t->ifindex = read_iface_ifindex(prefix, t->device);
t->iflink = read_iface_iflink(prefix, t->device);
t->next = root;
root = t;
#ifdef NETDATA_INTERNAL_CHECKS
info("added %s interface '%s', ifindex %u, iflink %u", scope, t->device, t->ifindex, t->iflink);
#endif
}
procfile_close(ff);
return root;
}
void free_iface(struct iface *iface) {
freez((void *)iface->device);
freez(iface);
}
void free_host_ifaces(struct iface *iface) {
while(iface) {
struct iface *t = iface->next;
free_iface(iface);
iface = t;
}
}
int iface_is_eligible(struct iface *iface) {
if(iface->iflink != iface->ifindex)
return 1;
return 0;
}
int eligible_ifaces(struct iface *root) {
int eligible = 0;
struct iface *t;
for(t = root; t ; t = t->next)
if(iface_is_eligible(t))
eligible++;
return eligible;
}
static void continue_as_child(void) {
pid_t child = fork();
int status;
pid_t ret;
if (child < 0)
error("fork() failed");
/* Only the child returns */
if (child == 0)
return;
for (;;) {
ret = waitpid(child, &status, WUNTRACED);
if ((ret == child) && (WIFSTOPPED(status))) {
/* The child suspended so suspend us as well */
kill(getpid(), SIGSTOP);
kill(child, SIGCONT);
} else {
break;
}
}
/* Return the child's exit code if possible */
if (WIFEXITED(status)) {
exit(WEXITSTATUS(status));
} else if (WIFSIGNALED(status)) {
kill(getpid(), WTERMSIG(status));
}
exit(EXIT_FAILURE);
}
int proc_pid_fd(const char *prefix, const char *ns, pid_t pid) {
if(!prefix) prefix = "";
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s/proc/%d/%s", prefix, (int)pid, ns);
int fd = open(filename, O_RDONLY);
if(fd == -1)
error("Cannot open proc_pid_fd() file '%s'", filename);
return fd;
}
static struct ns {
int nstype;
int fd;
int status;
const char *name;
const char *path;
} all_ns[] = {
// { .nstype = CLONE_NEWUSER, .fd = -1, .status = -1, .name = "user", .path = "ns/user" },
// { .nstype = CLONE_NEWCGROUP, .fd = -1, .status = -1, .name = "cgroup", .path = "ns/cgroup" },
// { .nstype = CLONE_NEWIPC, .fd = -1, .status = -1, .name = "ipc", .path = "ns/ipc" },
// { .nstype = CLONE_NEWUTS, .fd = -1, .status = -1, .name = "uts", .path = "ns/uts" },
{ .nstype = CLONE_NEWNET, .fd = -1, .status = -1, .name = "network", .path = "ns/net" },
{ .nstype = CLONE_NEWPID, .fd = -1, .status = -1, .name = "pid", .path = "ns/pid" },
{ .nstype = CLONE_NEWNS, .fd = -1, .status = -1, .name = "mount", .path = "ns/mnt" },
// terminator
{ .nstype = 0, .fd = -1, .status = -1, .name = NULL, .path = NULL }
};
int switch_namespace(const char *prefix, pid_t pid) {
#ifdef HAVE_SETNS
int i;
for(i = 0; all_ns[i].name ; i++)
all_ns[i].fd = proc_pid_fd(prefix, all_ns[i].path, pid);
int root_fd = proc_pid_fd(prefix, "root", pid);
int cwd_fd = proc_pid_fd(prefix, "cwd", pid);
setgroups(0, NULL);
// 2 passes - found it at nsenter source code
// this is related CLONE_NEWUSER functionality
// This code cannot switch user namespace (it can all the other namespaces)
// Fortunately, we don't need to switch user namespaces.
int pass;
for(pass = 0; pass < 2 ;pass++) {
for(i = 0; all_ns[i].name ; i++) {
if (all_ns[i].fd != -1 && all_ns[i].status == -1) {
if(setns(all_ns[i].fd, all_ns[i].nstype) == -1) {
if(pass == 1) {
all_ns[i].status = 0;
error("Cannot switch to %s namespace of pid %d", all_ns[i].name, (int) pid);
}
}
else
all_ns[i].status = 1;
}
}
}
setgroups(0, NULL);
if(root_fd != -1) {
if(fchdir(root_fd) < 0)
error("Cannot fchdir() to pid %d root directory", (int)pid);
if(chroot(".") < 0)
error("Cannot chroot() to pid %d root directory", (int)pid);
close(root_fd);
}
if(cwd_fd != -1) {
if(fchdir(cwd_fd) < 0)
error("Cannot fchdir() to pid %d current working directory", (int)pid);
close(cwd_fd);
}
int do_fork = 0;
for(i = 0; all_ns[i].name ; i++)
if(all_ns[i].fd != -1) {
// CLONE_NEWPID requires a fork() to become effective
if(all_ns[i].nstype == CLONE_NEWPID && all_ns[i].status)
do_fork = 1;
close(all_ns[i].fd);
}
if(do_fork)
continue_as_child();
return 0;
#else
errno = ENOSYS;
error("setns() is missing on this system.");
return 1;
#endif
}
pid_t read_pid_from_cgroup_file(const char *filename) {
int fd = open(filename, procfile_open_flags);
if(fd == -1) {
error("Cannot open pid_from_cgroup() file '%s'.", filename);
return 0;
}
FILE *fp = fdopen(fd, "r");
if(!fp) {
error("Cannot upgrade fd to fp for file '%s'.", filename);
return 0;
}
char buffer[100 + 1];
pid_t pid = 0;
char *s;
while((s = fgets(buffer, 100, fp))) {
buffer[100] = '\0';
pid = atoi(s);
if(pid > 0) break;
}
fclose(fp);
#ifdef NETDATA_INTERNAL_CHECKS
if(pid > 0) info("found pid %d on file '%s'", pid, filename);
#endif
return pid;
}
pid_t read_pid_from_cgroup_files(const char *path) {
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s/cgroup.procs", path);
pid_t pid = read_pid_from_cgroup_file(filename);
if(pid > 0) return pid;
snprintfz(filename, FILENAME_MAX, "%s/tasks", path);
return read_pid_from_cgroup_file(filename);
}
pid_t read_pid_from_cgroup(const char *path) {
pid_t pid = read_pid_from_cgroup_files(path);
if (pid > 0) return pid;
DIR *dir = opendir(path);
if (!dir) {
error("cannot read directory '%s'", path);
return 0;
}
struct dirent *de = NULL;
while ((de = readdir(dir))) {
if (de->d_type == DT_DIR
&& (
(de->d_name[0] == '.' && de->d_name[1] == '\0')
|| (de->d_name[0] == '.' && de->d_name[1] == '.' && de->d_name[2] == '\0')
))
continue;
if (de->d_type == DT_DIR) {
char filename[FILENAME_MAX + 1];
snprintfz(filename, FILENAME_MAX, "%s/%s", path, de->d_name);
pid = read_pid_from_cgroup(filename);
if(pid > 0) break;
}
}
closedir(dir);
return pid;
}
// ----------------------------------------------------------------------------
// send the result to netdata
struct found_device {
const char *host_device;
const char *guest_device;
uint32_t host_device_hash;
struct found_device *next;
} *detected_devices = NULL;
void add_device(const char *host, const char *guest) {
#ifdef NETDATA_INTERNAL_CHECKS
info("adding device with host '%s', guest '%s'", host, guest);
#endif
uint32_t hash = simple_hash(host);
if(guest && (!*guest || strcmp(host, guest) == 0))
guest = NULL;
struct found_device *f;
for(f = detected_devices; f ; f = f->next) {
if(f->host_device_hash == hash && !strcmp(host, f->host_device)) {
if(guest && (!f->guest_device || !strcmp(f->host_device, f->guest_device))) {
if(f->guest_device) freez((void *)f->guest_device);
f->guest_device = strdupz(guest);
}
return;
}
}
f = mallocz(sizeof(struct found_device));
f->host_device = strdupz(host);
f->host_device_hash = hash;
f->guest_device = (guest)?strdupz(guest):NULL;
f->next = detected_devices;
detected_devices = f;
}
int send_devices(void) {
int found = 0;
struct found_device *f;
for(f = detected_devices; f ; f = f->next) {
found++;
printf("%s %s\n", f->host_device, (f->guest_device)?f->guest_device:f->host_device);
}
return found;
}
// ----------------------------------------------------------------------------
// this function should be called only **ONCE**
// also it has to be the **LAST** to be called
// since it switches namespaces, so after this call, everything is different!
void detect_veth_interfaces(pid_t pid) {
struct iface *cgroup = NULL;
struct iface *host, *h, *c;
host = read_proc_net_dev("host", netdata_configured_host_prefix);
if(!host) {
errno = 0;
error("cannot read host interface list.");
goto cleanup;
}
if(!eligible_ifaces(host)) {
errno = 0;
info("there are no double-linked host interfaces available.");
goto cleanup;
}
if(switch_namespace(netdata_configured_host_prefix, pid)) {
errno = 0;
error("cannot switch to the namespace of pid %u", (unsigned int) pid);
goto cleanup;
}
#ifdef NETDATA_INTERNAL_CHECKS
info("switched to namespaces of pid %d", pid);
#endif
cgroup = read_proc_net_dev("cgroup", NULL);
if(!cgroup) {
errno = 0;
error("cannot read cgroup interface list.");
goto cleanup;
}
if(!eligible_ifaces(cgroup)) {
errno = 0;
error("there are not double-linked cgroup interfaces available.");
goto cleanup;
}
for(h = host; h ; h = h->next) {
if(iface_is_eligible(h)) {
for (c = cgroup; c; c = c->next) {
if(iface_is_eligible(c) && h->ifindex == c->iflink && h->iflink == c->ifindex) {
add_device(h->device, c->device);
}
}
}
}
cleanup:
free_host_ifaces(cgroup);
free_host_ifaces(host);
}
// ----------------------------------------------------------------------------
// call the external helper
#define CGROUP_NETWORK_INTERFACE_MAX_LINE 2048
void call_the_helper(pid_t pid, const char *cgroup) {
if(setresuid(0, 0, 0) == -1)
error("setresuid(0, 0, 0) failed.");
char command[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
if(cgroup)
snprintfz(command, CGROUP_NETWORK_INTERFACE_MAX_LINE, "exec " PLUGINS_DIR "/cgroup-network-helper.sh --cgroup '%s'", cgroup);
else
snprintfz(command, CGROUP_NETWORK_INTERFACE_MAX_LINE, "exec " PLUGINS_DIR "/cgroup-network-helper.sh --pid %d", pid);
info("running: %s", command);
pid_t cgroup_pid;
FILE *fp = mypopene(command, &cgroup_pid, environment);
if(fp) {
char buffer[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
char *s;
while((s = fgets(buffer, CGROUP_NETWORK_INTERFACE_MAX_LINE, fp))) {
trim(s);
if(*s && *s != '\n') {
char *t = s;
while(*t && *t != ' ') t++;
if(*t == ' ') {
*t = '\0';
t++;
}
if(!*s || !*t) continue;
add_device(s, t);
}
}
mypclose(fp, cgroup_pid);
}
else
error("cannot execute cgroup-network helper script: %s", command);
}
int is_valid_path_symbol(char c) {
switch(c) {
case '/': // path separators
case '\\': // needed for virsh domains \x2d1\x2dname
case ' ': // space
case '-': // hyphen
case '_': // underscore
case '.': // dot
case ',': // comma
return 1;
default:
return 0;
}
}
// we will pass this path a shell script running as root
// so, we need to make sure the path will be valid
// and will not include anything that could allow
// the caller use shell expansion for gaining escalated
// privileges.
int verify_path(const char *path) {
struct stat sb;
char c;
const char *s = path;
while((c = *s++)) {
if(!( isalnum(c) || is_valid_path_symbol(c) )) {
error("invalid character in path '%s'", path);
return -1;
}
}
if(strstr(path, "\\") && !strstr(path, "\\x")) {
error("invalid escape sequence in path '%s'", path);
return 1;
}
if(strstr(path, "/../")) {
error("invalid parent path sequence detected in '%s'", path);
return 1;
}
if(path[0] != '/') {
error("only absolute path names are supported - invalid path '%s'", path);
return -1;
}
if (stat(path, &sb) == -1) {
error("cannot stat() path '%s'", path);
return -1;
}
if((sb.st_mode & S_IFMT) != S_IFDIR) {
error("path '%s' is not a directory", path);
return -1;
}
return 0;
}
/*
char *fix_path_variable(void) {
const char *path = getenv("PATH");
if(!path || !*path) return 0;
char *p = strdupz(path);
char *safe_path = callocz(1, strlen(p) + strlen("PATH=") + 1);
strcpy(safe_path, "PATH=");
int added = 0;
char *ptr = p;
while(ptr && *ptr) {
char *s = strsep(&ptr, ":");
if(s && *s) {
if(verify_path(s) == -1) {
error("the PATH variable includes an invalid path '%s' - removed it.", s);
}
else {
info("the PATH variable includes a valid path '%s'.", s);
if(added) strcat(safe_path, ":");
strcat(safe_path, s);
added++;
}
}
}
info("unsafe PATH: '%s'.", path);
info(" safe PATH: '%s'.", safe_path);
freez(p);
return safe_path;
}
*/
// ----------------------------------------------------------------------------
// main
void usage(void) {
fprintf(stderr, "%s [ -p PID | --pid PID | --cgroup /path/to/cgroup ]\n", program_name);
exit(1);
}
int main(int argc, char **argv) {
pid_t pid = 0;
program_name = argv[0];
program_version = VERSION;
error_log_syslog = 0;
// since cgroup-network runs as root, prevent it from opening symbolic links
procfile_open_flags = O_RDONLY|O_NOFOLLOW;
// ------------------------------------------------------------------------
// make sure NETDATA_HOST_PREFIX is safe
netdata_configured_host_prefix = getenv("NETDATA_HOST_PREFIX");
if(verify_netdata_host_prefix() == -1) exit(1);
if(netdata_configured_host_prefix[0] != '\0' && verify_path(netdata_configured_host_prefix) == -1)
fatal("invalid NETDATA_HOST_PREFIX '%s'", netdata_configured_host_prefix);
// ------------------------------------------------------------------------
// build a safe environment for our script
// the first environment variable is a fixed PATH=
snprintfz(environment_variable2, sizeof(environment_variable2) - 1, "NETDATA_HOST_PREFIX=%s", netdata_configured_host_prefix);
// ------------------------------------------------------------------------
if(argc == 2 && (!strcmp(argv[1], "version") || !strcmp(argv[1], "-version") || !strcmp(argv[1], "--version") || !strcmp(argv[1], "-v") || !strcmp(argv[1], "-V"))) {
fprintf(stderr, "cgroup-network %s\n", VERSION);
exit(0);
}
if(argc != 3)
usage();
if(!strcmp(argv[1], "-p") || !strcmp(argv[1], "--pid")) {
pid = atoi(argv[2]);
if(pid <= 0) {
errno = 0;
error("Invalid pid %d given", (int) pid);
return 2;
}
call_the_helper(pid, NULL);
}
else if(!strcmp(argv[1], "--cgroup")) {
char *cgroup = argv[2];
if(verify_path(cgroup) == -1) {
error("cgroup '%s' does not exist or is not valid.", cgroup);
return 1;
}
pid = read_pid_from_cgroup(cgroup);
call_the_helper(pid, cgroup);
if(pid <= 0 && !detected_devices) {
errno = 0;
error("Cannot find a cgroup PID from cgroup '%s'", cgroup);
}
}
else
usage();
if(pid > 0)
detect_veth_interfaces(pid);
int found = send_devices();
if(found <= 0) return 1;
return 0;
}
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