docs: Add supported versions and fix-backport policy

[lttng-tools.git] / src / common / compat / socket.hpp

/*
 * Copyright (C) 2011 David Goulet <dgoulet@efficios.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 */

#ifndef _COMPAT_SOCKET_H
#define _COMPAT_SOCKET_H

#include <common/macros.hpp>

#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>

#ifndef MSG_NOSIGNAL
#ifdef SO_NOSIGPIPE
#define MSG_NOSIGNAL SO_NOSIGPIPE
#endif
#endif

#if defined(MSG_NOSIGNAL)
static inline ssize_t lttng_recvmsg_nosigpipe(int sockfd, struct msghdr *msg)
{
	return recvmsg(sockfd, msg, MSG_NOSIGNAL);
}
#else

#include <common/compat/errno.hpp>

#include <signal.h>

static inline ssize_t lttng_recvmsg_nosigpipe(int sockfd, struct msghdr *msg)
{
	ssize_t received;
	int saved_err;
	sigset_t sigpipe_set, pending_set, old_set;
	int sigpipe_was_pending;

	/*
	 * Discard the SIGPIPE from send(), not disturbing any SIGPIPE
	 * that might be already pending. If a bogus SIGPIPE is sent to
	 * the entire process concurrently by a malicious user, it may
	 * be simply discarded.
	 */
	if (sigemptyset(&pending_set)) {
		return -1;
	}
	/*
	 * sigpending returns the mask of signals that are _both_
	 * blocked for the thread _and_ pending for either the thread or
	 * the entire process.
	 */
	if (sigpending(&pending_set)) {
		return -1;
	}
	sigpipe_was_pending = sigismember(&pending_set, SIGPIPE);
	/*
	 * If sigpipe was pending, it means it was already blocked, so
	 * no need to block it.
	 */
	if (!sigpipe_was_pending) {
		if (sigemptyset(&sigpipe_set)) {
			return -1;
		}
		if (sigaddset(&sigpipe_set, SIGPIPE)) {
			return -1;
		}
		if (pthread_sigmask(SIG_BLOCK, &sigpipe_set, &old_set)) {
			return -1;
		}
	}

	/* Send and save errno. */
	received = recvmsg(sockfd, msg, 0);
	saved_err = errno;

	if (received == -1 && errno == EPIPE && !sigpipe_was_pending) {
		struct timespec timeout = { 0, 0 };
		int ret;

		do {
			ret = sigtimedwait(&sigpipe_set, NULL, &timeout);
		} while (ret == -1 && errno == EINTR);
	}
	if (!sigpipe_was_pending) {
		if (pthread_sigmask(SIG_SETMASK, &old_set, NULL)) {
			return -1;
		}
	}
	/* Restore send() errno */
	errno = saved_err;

	return received;
}
#endif

#ifdef __sun__

#ifndef CMSG_ALIGN
#ifdef _CMSG_DATA_ALIGN
#define CMSG_ALIGN(len) _CMSG_DATA_ALIGN(len)
#else
/* aligning to sizeof (long) is assumed to be portable (fd.o#40235) */
#define CMSG_ALIGN(len) (((len) + sizeof(long) - 1) & ~(sizeof(long) - 1))
#endif
#ifndef CMSG_SPACE
#define CMSG_SPACE(len) (CMSG_ALIGN(sizeof(struct cmsghdr)) + CMSG_ALIGN(len))
#endif
#ifndef CMSG_LEN
#define CMSG_LEN(len) (CMSG_ALIGN(sizeof(struct cmsghdr)) + (len))
#endif
#endif

#include <ucred.h>

static inline int getpeereid(int s, uid_t *euid, gid_t *gid)
{
	int ret = 0;
	ucred_t *ucred = NULL;

	ret = getpeerucred(s, &ucred);
	if (ret == -1) {
		goto end;
	}

	ret = ucred_geteuid(ucred);
	if (ret == -1) {
		goto free;
	}
	*euid = ret;

	ret = ucred_getrgid(ucred);
	if (ret == -1) {
		goto free;
	}
	*gid = ret;

	ret = 0;
free:
	ucred_free(ucred);
end:
	return ret;
}
#endif /* __sun__ */

#if defined(__linux__) || defined(__CYGWIN__)

#define LTTNG_SOCK_CREDS SCM_CREDENTIALS

using lttng_sock_cred = struct ucred;

#define LTTNG_SOCK_SET_UID_CRED(c, u) LTTNG_REF(c)->uid = u
#define LTTNG_SOCK_SET_GID_CRED(c, g) LTTNG_REF(c)->gid = g
#define LTTNG_SOCK_SET_PID_CRED(c, p) LTTNG_REF(c)->pid = p

#define LTTNG_SOCK_GET_UID_CRED(c) LTTNG_REF(c)->uid
#define LTTNG_SOCK_GET_GID_CRED(c) LTTNG_REF(c)->gid
#define LTTNG_SOCK_GET_PID_CRED(c) LTTNG_REF(c)->pid

#elif (defined(__FreeBSD__) || defined(__sun__) || defined(__APPLE__))

struct lttng_sock_cred {
	uid_t uid;
	gid_t gid;
	pid_t pid;
};

typedef struct lttng_sock_cred lttng_sock_cred;

#define LTTNG_SOCK_SET_UID_CRED(c, u) LTTNG_REF(c)->uid = u
#define LTTNG_SOCK_SET_GID_CRED(c, g) LTTNG_REF(c)->gid = g
#define LTTNG_SOCK_SET_PID_CRED(c, p) LTTNG_REF(c)->pid = p

#define LTTNG_SOCK_GET_UID_CRED(c) LTTNG_REF(c)->uid
#define LTTNG_SOCK_GET_GID_CRED(c) LTTNG_REF(c)->gid
#define LTTNG_SOCK_GET_PID_CRED(c) LTTNG_REF(c)->pid

#ifdef __APPLE__

static inline int lttng_get_unix_socket_peer_pid(int socket_fd, pid_t *pid)
{
	socklen_t pid_len = (socklen_t) sizeof(*pid);

	/* The getsockopt LOCAL_PEERPID option is available since macOS 10.8. */
	return getsockopt(socket_fd, SOL_LOCAL, LOCAL_PEERPID, pid, &pid_len);
}

#elif defined(__sun__)

/* Use the getpeerucreds interface on Solaris. */
static inline int lttng_get_unix_socket_peer_pid(int socket_fd, pid_t *pid)
{
	int ret = 0;
	ucred_t *ucred = NULL;

	ret = getpeerucred(s, &ucred);
	if (ret == -1) {
		goto end;
	}

	ret = ucred_getpid(ucred);
	if (ret == -1) {
		goto free;
	}

	*pid = ret;
	ret = 0;
free:
	ucred_free(ucred);
end:
	return ret;
}

#elif defined(__FreeBSD__)

#include <sys/ucred.h>

static inline int lttng_get_unix_socket_peer_pid(int socket_fd, pid_t *pid)
{
	int ret;
	struct xucred sock_creds = {};
	socklen_t sock_creds_len = (socklen_t) sizeof(sock_creds);

	/* Only available in FreeBSD 13.0 and up. */
	ret = getsockopt(socket_fd, SOL_LOCAL, LOCAL_PEERCRED, &sock_creds, &sock_creds_len);
	if (ret) {
		goto end;
	}

	*pid = sock_creds.cr_pid;
end:
	return ret;
}

#endif /* __APPLE__ */

static inline int lttng_get_unix_socket_peer_creds(int socket_fd, struct lttng_sock_cred *creds)
{
	int ret;

	/* This is a BSD extension that is supported by Cygwin. */
	ret = getpeereid(socket_fd, &creds->uid, &creds->gid);
	if (ret) {
		goto end;
	}

	/*
	 * Getting a peer's PID is a bit more troublesome as it is platform
	 * specific.
	 */
	ret = lttng_get_unix_socket_peer_pid(socket_fd, &creds->pid);
end:
	return ret;
}

#else
#error "Please add support for your OS."
#endif /* __linux__ , __FreeBSD__, __APPLE__ */

#endif /* _COMPAT_SOCKET_H */