hba.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

			(errcode(ERRCODE_CONFIG_FILE_ERROR),
			 errmsg("missing entry in file \"%s\" at end of line %d",
					IdentFileName, line_number)));
	*error_p = true;
}


/*
 *	Scan the (pre-parsed) ident usermap file line by line, looking for a match
 *
 *	See if the user with ident username "ident_user" is allowed to act
 *	as Postgres user "pgrole" according to usermap "usermap_name".
 *
 *	Special case: For usermap "samerole", don't look in the usermap
 *	file.  That's an implied map where "pgrole" must be identical to
 *	"ident_user" in order to be authorized.
 *
 *	Iff authorized, return true.
 */
static bool
check_ident_usermap(const char *usermap_name,
					const char *pg_role,
					const char *ident_user)
{
	bool		found_entry = false,
				error = false;

	if (usermap_name == NULL || usermap_name[0] == '\0')
	{
		ereport(LOG,
				(errcode(ERRCODE_CONFIG_FILE_ERROR),
		   errmsg("cannot use Ident authentication without usermap field")));
		found_entry = false;
	}
	else if (strcmp(usermap_name, "sameuser\n") == 0 ||
			 strcmp(usermap_name, "samerole\n") == 0)
	{
		if (strcmp(pg_role, ident_user) == 0)
			found_entry = true;
		else
			found_entry = false;
	}
	else
	{
		ListCell   *line_cell,
				   *num_cell;

		forboth(line_cell, ident_lines, num_cell, ident_line_nums)
		{
			parse_ident_usermap(lfirst(line_cell), lfirst_int(num_cell),
								usermap_name, pg_role, ident_user,
								&found_entry, &error);
			if (found_entry || error)
				break;
		}
	}
	return found_entry;
}


/*
 * Read the ident config file and create a List of Lists of tokens in the file.
 */
void
load_ident(void)
{
	FILE	   *file;

	if (ident_lines || ident_line_nums)
		free_lines(&ident_lines, &ident_line_nums);

	file = AllocateFile(IdentFileName, "r");
	if (file == NULL)
	{
		/* not fatal ... we just won't do any special ident maps */
		ereport(LOG,
				(errcode_for_file_access(),
				 errmsg("could not open Ident usermap file \"%s\": %m",
						IdentFileName)));
	}
	else
	{
		tokenize_file(IdentFileName, file, &ident_lines, &ident_line_nums);
		FreeFile(file);
	}
}


/*
 *	Parse the string "*ident_response" as a response from a query to an Ident
 *	server.  If it's a normal response indicating a user name, return true
 *	and store the user name at *ident_user. If it's anything else,
 *	return false.
 */
static bool
interpret_ident_response(const char *ident_response,
						 char *ident_user)
{
	const char *cursor = ident_response;		/* Cursor into *ident_response */

	/*
	 * Ident's response, in the telnet tradition, should end in crlf (\r\n).
	 */
	if (strlen(ident_response) < 2)
		return false;
	else if (ident_response[strlen(ident_response) - 2] != '\r')
		return false;
	else
	{
		while (*cursor != ':' && *cursor != '\r')
			cursor++;			/* skip port field */

		if (*cursor != ':')
			return false;
		else
		{
			/* We're positioned to colon before response type field */
			char		response_type[80];
			int			i;		/* Index into *response_type */

			cursor++;			/* Go over colon */
			while (pg_isblank(*cursor))
				cursor++;		/* skip blanks */
			i = 0;
			while (*cursor != ':' && *cursor != '\r' && !pg_isblank(*cursor) &&
				   i < (int) (sizeof(response_type) - 1))
				response_type[i++] = *cursor++;
			response_type[i] = '\0';
			while (pg_isblank(*cursor))
				cursor++;		/* skip blanks */
			if (strcmp(response_type, "USERID") != 0)
				return false;
			else
			{
				/*
				 * It's a USERID response.  Good.  "cursor" should be pointing
				 * to the colon that precedes the operating system type.
				 */
				if (*cursor != ':')
					return false;
				else
				{
					cursor++;	/* Go over colon */
					/* Skip over operating system field. */
					while (*cursor != ':' && *cursor != '\r')
						cursor++;
					if (*cursor != ':')
						return false;
					else
					{
						int			i;	/* Index into *ident_user */

						cursor++;		/* Go over colon */
						while (pg_isblank(*cursor))
							cursor++;	/* skip blanks */
						/* Rest of line is user name.  Copy it over. */
						i = 0;
						while (*cursor != '\r' && i < IDENT_USERNAME_MAX)
							ident_user[i++] = *cursor++;
						ident_user[i] = '\0';
						return true;
					}
				}
			}
		}
	}
}


/*
 *	Talk to the ident server on host "remote_ip_addr" and find out who
 *	owns the tcp connection from his port "remote_port" to port
 *	"local_port_addr" on host "local_ip_addr".	Return the user name the
 *	ident server gives as "*ident_user".
 *
 *	IP addresses and port numbers are in network byte order.
 *
 *	But iff we're unable to get the information from ident, return false.
 */
static bool
ident_inet(const SockAddr remote_addr,
		   const SockAddr local_addr,
		   char *ident_user)
{
	int			sock_fd,		/* File descriptor for socket on which we talk
								 * to Ident */
				rc;				/* Return code from a locally called function */
	bool		ident_return;
	char		remote_addr_s[NI_MAXHOST];
	char		remote_port[NI_MAXSERV];
	char		local_addr_s[NI_MAXHOST];
	char		local_port[NI_MAXSERV];
	char		ident_port[NI_MAXSERV];
	char		ident_query[80];
	char		ident_response[80 + IDENT_USERNAME_MAX];
	struct addrinfo *ident_serv = NULL,
			   *la = NULL,
				hints;

	/*
	 * Might look a little weird to first convert it to text and then back to
	 * sockaddr, but it's protocol independent.
	 */
	pg_getnameinfo_all(&remote_addr.addr, remote_addr.salen,
					   remote_addr_s, sizeof(remote_addr_s),
					   remote_port, sizeof(remote_port),
					   NI_NUMERICHOST | NI_NUMERICSERV);
	pg_getnameinfo_all(&local_addr.addr, local_addr.salen,
					   local_addr_s, sizeof(local_addr_s),
					   local_port, sizeof(local_port),
					   NI_NUMERICHOST | NI_NUMERICSERV);

	snprintf(ident_port, sizeof(ident_port), "%d", IDENT_PORT);
	hints.ai_flags = AI_NUMERICHOST;
	hints.ai_family = remote_addr.addr.ss_family;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = 0;
	hints.ai_addrlen = 0;
	hints.ai_canonname = NULL;
	hints.ai_addr = NULL;
	hints.ai_next = NULL;
	rc = pg_getaddrinfo_all(remote_addr_s, ident_port, &hints, &ident_serv);
	if (rc || !ident_serv)
	{
		if (ident_serv)
			pg_freeaddrinfo_all(hints.ai_family, ident_serv);
		return false;			/* we don't expect this to happen */
	}

	hints.ai_flags = AI_NUMERICHOST;
	hints.ai_family = local_addr.addr.ss_family;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = 0;
	hints.ai_addrlen = 0;
	hints.ai_canonname = NULL;
	hints.ai_addr = NULL;
	hints.ai_next = NULL;
	rc = pg_getaddrinfo_all(local_addr_s, NULL, &hints, &la);
	if (rc || !la)
	{
		if (la)
			pg_freeaddrinfo_all(hints.ai_family, la);
		return false;			/* we don't expect this to happen */
	}

	sock_fd = socket(ident_serv->ai_family, ident_serv->ai_socktype,
					 ident_serv->ai_protocol);
	if (sock_fd < 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not create socket for Ident connection: %m")));
		ident_return = false;
		goto ident_inet_done;
	}

	/*
	 * Bind to the address which the client originally contacted, otherwise
	 * the ident server won't be able to match up the right connection. This
	 * is necessary if the PostgreSQL server is running on an IP alias.
	 */
	rc = bind(sock_fd, la->ai_addr, la->ai_addrlen);
	if (rc != 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not bind to local address \"%s\": %m",
						local_addr_s)));
		ident_return = false;
		goto ident_inet_done;
	}

	rc = connect(sock_fd, ident_serv->ai_addr,
				 ident_serv->ai_addrlen);
	if (rc != 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not connect to Ident server at address \"%s\", port %s: %m",
						remote_addr_s, ident_port)));
		ident_return = false;
		goto ident_inet_done;
	}

	/* The query we send to the Ident server */
	snprintf(ident_query, sizeof(ident_query), "%s,%s\r\n",
			 remote_port, local_port);

	/* loop in case send is interrupted */
	do
	{
		rc = send(sock_fd, ident_query, strlen(ident_query), 0);
	} while (rc < 0 && errno == EINTR);

	if (rc < 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not send query to Ident server at address \"%s\", port %s: %m",
						remote_addr_s, ident_port)));
		ident_return = false;
		goto ident_inet_done;
	}

	do
	{
		rc = recv(sock_fd, ident_response, sizeof(ident_response) - 1, 0);
	} while (rc < 0 && errno == EINTR);

	if (rc < 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not receive response from Ident server at address \"%s\", port %s: %m",
						remote_addr_s, ident_port)));
		ident_return = false;
		goto ident_inet_done;
	}

	ident_response[rc] = '\0';
	ident_return = interpret_ident_response(ident_response, ident_user);
	if (!ident_return)
		ereport(LOG,
			(errmsg("invalidly formatted response from Ident server: \"%s\"",
					ident_response)));

ident_inet_done:
	if (sock_fd >= 0)
		closesocket(sock_fd);
	pg_freeaddrinfo_all(remote_addr.addr.ss_family, ident_serv);
	pg_freeaddrinfo_all(local_addr.addr.ss_family, la);
	return ident_return;
}

/*
 *	Ask kernel about the credentials of the connecting process and
 *	determine the symbolic name of the corresponding user.
 *
 *	Returns either true and the username put into "ident_user",
 *	or false if we were unable to determine the username.
 */
#ifdef HAVE_UNIX_SOCKETS

static bool
ident_unix(int sock, char *ident_user)
{
#if defined(HAVE_GETPEEREID)
	/* OpenBSD style:  */
	uid_t		uid;
	gid_t		gid;
	struct passwd *pass;

	errno = 0;
	if (getpeereid(sock, &uid, &gid) != 0)
	{
		/* We didn't get a valid credentials struct. */
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not get peer credentials: %m")));
		return false;
	}

	pass = getpwuid(uid);

	if (pass == NULL)
	{
		ereport(LOG,
				(errmsg("local user with ID %d does not exist",
						(int) uid)));
		return false;
	}

	StrNCpy(ident_user, pass->pw_name, IDENT_USERNAME_MAX + 1);

	return true;
#elif defined(SO_PEERCRED)
	/* Linux style: use getsockopt(SO_PEERCRED) */
	struct ucred peercred;
	ACCEPT_TYPE_ARG3 so_len = sizeof(peercred);
	struct passwd *pass;

	errno = 0;
	if (getsockopt(sock, SOL_SOCKET, SO_PEERCRED, &peercred, &so_len) != 0 ||
		so_len != sizeof(peercred))
	{
		/* We didn't get a valid credentials struct. */
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not get peer credentials: %m")));
		return false;
	}

	pass = getpwuid(peercred.uid);

	if (pass == NULL)
	{
		ereport(LOG,
				(errmsg("local user with ID %d does not exist",
						(int) peercred.uid)));
		return false;
	}

	StrNCpy(ident_user, pass->pw_name, IDENT_USERNAME_MAX + 1);

	return true;
#elif defined(HAVE_STRUCT_CMSGCRED) || defined(HAVE_STRUCT_FCRED) || (defined(HAVE_STRUCT_SOCKCRED) && defined(LOCAL_CREDS))
	struct msghdr msg;

/* Credentials structure */
#if defined(HAVE_STRUCT_CMSGCRED)
	typedef struct cmsgcred Cred;

#define cruid cmcred_uid
#elif defined(HAVE_STRUCT_FCRED)
	typedef struct fcred Cred;

#define cruid fc_uid
#elif defined(HAVE_STRUCT_SOCKCRED)
	typedef struct sockcred Cred;

#define cruid sc_uid
#endif
	Cred	   *cred;

	/* Compute size without padding */
	char		cmsgmem[ALIGN(sizeof(struct cmsghdr)) + ALIGN(sizeof(Cred))];	/* for NetBSD */

	/* Point to start of first structure */
	struct cmsghdr *cmsg = (struct cmsghdr *) cmsgmem;

	struct iovec iov;
	char		buf;
	struct passwd *pw;

	memset(&msg, 0, sizeof(msg));
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = (char *) cmsg;
	msg.msg_controllen = sizeof(cmsgmem);
	memset(cmsg, 0, sizeof(cmsgmem));

	/*
	 * The one character which is received here is not meaningful; its
	 * purposes is only to make sure that recvmsg() blocks long enough for the
	 * other side to send its credentials.
	 */
	iov.iov_base = &buf;
	iov.iov_len = 1;

	if (recvmsg(sock, &msg, 0) < 0 ||
		cmsg->cmsg_len < sizeof(cmsgmem) ||
		cmsg->cmsg_type != SCM_CREDS)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("could not get peer credentials: %m")));
		return false;
	}

	cred = (Cred *) CMSG_DATA(cmsg);

	pw = getpwuid(cred->cruid);

	if (pw == NULL)
	{
		ereport(LOG,
				(errmsg("local user with ID %d does not exist",
						(int) cred->cruid)));
		return false;
	}

	StrNCpy(ident_user, pw->pw_name, IDENT_USERNAME_MAX + 1);

	return true;
#else
	ereport(LOG,
			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
			 errmsg("Ident authentication is not supported on local connections on this platform")));

	return false;
#endif
}
#endif   /* HAVE_UNIX_SOCKETS */


/*
 *	Determine the username of the initiator of the connection described
 *	by "port".	Then look in the usermap file under the usermap
 *	port->auth_arg and see if that user is equivalent to Postgres user
 *	port->user.
 *
 *	Return STATUS_OK if yes, STATUS_ERROR if no match (or couldn't get info).
 */
int
authident(hbaPort *port)
{
	char		ident_user[IDENT_USERNAME_MAX + 1];

	switch (port->raddr.addr.ss_family)
	{
		case AF_INET:
#ifdef	HAVE_IPV6
		case AF_INET6:
#endif
			if (!ident_inet(port->raddr, port->laddr, ident_user))
				return STATUS_ERROR;
			break;

#ifdef HAVE_UNIX_SOCKETS
		case AF_UNIX:
			if (!ident_unix(port->sock, ident_user))
				return STATUS_ERROR;
			break;
#endif

		default:
			return STATUS_ERROR;
	}

	ereport(DEBUG2,
			(errmsg("Ident protocol identifies remote user as \"%s\"",
					ident_user)));

	if (check_ident_usermap(port->auth_arg, port->user_name, ident_user))
		return STATUS_OK;
	else
		return STATUS_ERROR;
}


/*
 *	Determine what authentication method should be used when accessing database
 *	"database" from frontend "raddr", user "user".	Return the method and
 *	an optional argument (stored in fields of *port), and STATUS_OK.
 *
 *	Note that STATUS_ERROR indicates a problem with the hba config file.
 *	If the file is OK but does not contain any entry matching the request,
 *	we return STATUS_OK and method = uaReject.
 */
int
hba_getauthmethod(hbaPort *port)
{
	if (check_hba(port))
		return STATUS_OK;
	else
		return STATUS_ERROR;
}