src/lib-master/master-login.c

	master-login.c revision 2ac5f36aa7c2e7a07ba8815d43a6d7483f62e74c
/* Copyright (c) 2009-2016 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "ioloop.h"
#include "ostream.h"
#include "fdpass.h"
#include "fd-close-on-exec.h"
#include "llist.h"
#include "str.h"
#include "strescape.h"
#include "master-service-private.h"
#include "master-login.h"
#include "master-login-auth.h"

#include <sys/stat.h>
#include <unistd.h>

#define master_login_conn_is_closed(conn) \
    ((conn)->fd == -1)
#define master_login_conn_has_clients(conn) \
    ((conn)->refcount > 1)

struct master_login_connection {
    struct master_login_connection *prev, *next;

    struct master_login *login;
    int refcount;
    int fd;
    struct io *io;
    struct ostream *output;

    bool login_success:1;
};

struct master_login_postlogin {
    struct master_login_client *client;

    int fd;
    struct io *io;
    struct timeout *to;
    string_t *input;
    char *username;
};

struct master_login {
    struct master_service *service;
    master_login_callback_t *callback;
    master_login_failure_callback_t *failure_callback;
    struct master_login_connection *conns;
    struct master_login_auth *auth;
    char *postlogin_socket_path;
    unsigned int postlogin_timeout_secs;

    bool stopping:1;
};

static void master_login_conn_close(struct master_login_connection *conn);
static void master_login_conn_unref(struct master_login_connection **_conn);

struct master_login *
master_login_init(struct master_service *service,
          const struct master_login_settings *set)
{
    struct master_login *login;

    i_assert(set->postlogin_socket_path == NULL ||
         set->postlogin_timeout_secs > 0);

    login = i_new(struct master_login, 1);
    login->service = service;
    login->callback = set->callback;
    login->failure_callback = set->failure_callback;
    login->auth = master_login_auth_init(set->auth_socket_path,
                         set->request_auth_token);
    login->postlogin_socket_path = i_strdup(set->postlogin_socket_path);
    login->postlogin_timeout_secs = set->postlogin_timeout_secs;

    i_assert(service->login == NULL);
    service->login = login;
    return login;
}

void master_login_deinit(struct master_login **_login)
{
    struct master_login *login = *_login;

    *_login = NULL;

    i_assert(login->service->login == login);
    login->service->login = NULL;

    master_login_auth_deinit(&login->auth);
    while (login->conns != NULL) {
        struct master_login_connection *conn = login->conns;

        master_login_conn_close(conn);
        master_login_conn_unref(&conn);
    }
    i_free(login->postlogin_socket_path);
    i_free(login);
}

static int
master_login_conn_read_request(struct master_login_connection *conn,
                   struct master_auth_request *req_r,
                   unsigned char data[MASTER_AUTH_MAX_DATA_SIZE],
                   int *client_fd_r)
{
    struct stat st;
    ssize_t ret;

    *client_fd_r = -1;

    ret = fd_read(conn->fd, req_r, sizeof(*req_r), client_fd_r);
    if (ret != sizeof(*req_r)) {
        if (ret == 0) {
            /* disconnected */
            if (master_login_conn_has_clients(conn))
                i_error("Login client disconnected too early");
        } else if (ret > 0) {
            /* request wasn't fully read */
            i_error("fd_read() partial input (%d/%d)",
                (int)ret, (int)sizeof(*req_r));
        } else {
            if (errno == EAGAIN)
                return 0;

            i_error("fd_read() failed: %m");
        }
        return -1;
    }

    if (req_r->data_size != 0) {
        if (req_r->data_size > MASTER_AUTH_MAX_DATA_SIZE) {
            i_error("Too large auth data_size sent");
            return -1;
        }
        /* @UNSAFE */
        ret = read(conn->fd, data, req_r->data_size);
        if (ret != (ssize_t)req_r->data_size) {
            if (ret == 0) {
                /* disconnected */
                if (master_login_conn_has_clients(conn)) {
                    i_error("Login client disconnected too early "
                        "(while reading data)");
                }
            } else if (ret > 0) {
                /* request wasn't fully read */
                i_error("Data read partially %d/%u",
                    (int)ret, req_r->data_size);
            } else {
                i_error("read(data) failed: %m");
            }
            return -1;
        }
    }

    if (*client_fd_r == -1) {
        i_error("Auth request missing a file descriptor");
        return -1;
    }

    if (fstat(*client_fd_r, &st) < 0) {
        i_error("fstat(fd_read client) failed: %m");
        return -1;
    }
    if (st.st_ino != req_r->ino) {
        i_error("Auth request inode mismatch: %s != %s",
            dec2str(st.st_ino), dec2str(req_r->ino));
        return -1;
    }
    return 1;
}

static void master_login_client_free(struct master_login_client **_client)
{
    struct master_login_client *client = *_client;

    *_client = NULL;
    if (client->fd != -1) {
        if (close(client->fd) < 0)
            i_error("close(fd_read client) failed: %m");
        /* this client failed (login callback wasn't called).
           reset prefix to default. */
        i_set_failure_prefix("%s: ", client->conn->login->service->name);
    }

    /* FIXME: currently we create a separate connection for each request,
       so close the connection after we're done with this client */
    if (!master_login_conn_is_closed(client->conn)) {
        i_assert(client->conn->refcount > 1);
        client->conn->refcount--;
    }
    master_login_conn_unref(&client->conn);
    i_free(client->session_id);
    i_free(client);
}

static void master_login_auth_finish(struct master_login_client *client,
                     const char *const *auth_args)
{
    struct master_login *login = client->conn->login;
    struct master_service *service = login->service;
    bool close_sockets;

    close_sockets = service->master_status.available_count == 0 &&
        service->service_count_left == 1;

    client->conn->login_success = TRUE;
    login->callback(client, auth_args[0], auth_args+1);

    if (close_sockets) {
        /* we're dying as soon as this connection closes. */
        i_assert(master_login_auth_request_count(login->auth) == 0);
        master_login_auth_disconnect(login->auth);

        master_service_close_config_fd(service);
    } else if (login->stopping) {
        /* try stopping again */
        master_login_stop(login);
    }

    client->fd = -1;
    master_login_client_free(&client);
}

static void master_login_postlogin_free(struct master_login_postlogin *pl)
{
    timeout_remove(&pl->to);
    io_remove(&pl->io);
    if (close(pl->fd) < 0)
        i_error("close(postlogin) failed: %m");
    str_free(&pl->input);
    i_free(pl->username);
    i_free(pl);
}

static void master_login_postlogin_input(struct master_login_postlogin *pl)
{
    struct master_login *login = pl->client->conn->login;
    char buf[1024];
    const char *const *auth_args;
    size_t len;
    ssize_t ret;
    int fd = -1;

    while ((ret = fd_read(pl->fd, buf, sizeof(buf), &fd)) > 0) {
        if (fd != -1) {
            /* post-login script replaced fd */
            if (close(pl->client->fd) < 0)
                i_error("close(client) failed: %m");
            pl->client->fd = fd;
        }
        str_append_n(pl->input, buf, ret);
    }

    len = str_len(pl->input);
    if (len > 0 && str_c(pl->input)[len-1] == '\n') {
        /* finished reading the input */
        str_truncate(pl->input, len-1);
    } else {
        if (ret < 0) {
            if (errno == EAGAIN)
                return;

            i_error("fd_read(%s) failed: %m",
                login->postlogin_socket_path);
        } else if (str_len(pl->input) > 0) {
            i_error("fd_read(%s) failed: disconnected",
                login->postlogin_socket_path);
        } else {
            i_info("Post-login script denied access to user %s",
                   pl->username);
        }
        master_login_client_free(&pl->client);
        master_login_postlogin_free(pl);
        return;
    }

    auth_args = t_strsplit_tabescaped(str_c(pl->input));
    master_login_auth_finish(pl->client, auth_args);
    master_login_postlogin_free(pl);
}

static void master_login_postlogin_timeout(struct master_login_postlogin *pl)
{
    struct master_login *login = pl->client->conn->login;

    i_error("%s: Timeout waiting for post-login script to finish, aborting",
        login->postlogin_socket_path);

    master_login_client_free(&pl->client);
    master_login_postlogin_free(pl);
}

static int master_login_postlogin(struct master_login_client *client,
                  const char *const *auth_args)
{
    struct master_login *login = client->conn->login;
    struct master_login_postlogin *pl;
    string_t *str;
    unsigned int i;
    int fd;
    ssize_t ret;

    fd = net_connect_unix_with_retries(login->postlogin_socket_path, 1000);
    if (fd == -1) {
        i_error("net_connect_unix(%s) failed: %m%s",
            login->postlogin_socket_path, errno != EAGAIN ? "" :
            " - http://wiki2.dovecot.org/SocketUnavailable");
        return -1;
    }

    str = t_str_new(256);
    str_printfa(str, "VERSION\tscript-login\t1\t0\n"
            "%s\t%s", net_ip2addr(&client->auth_req.local_ip),
            net_ip2addr(&client->auth_req.remote_ip));
    for (i = 0; auth_args[i] != NULL; i++) {
        str_append_c(str, '\t');
        str_append_tabescaped(str, auth_args[i]);
    }
    str_append_c(str, '\n');
    ret = fd_send(fd, client->fd, str_data(str), str_len(str));
    if (ret != (ssize_t)str_len(str)) {
        if (ret < 0) {
            i_error("write(%s) failed: %m",
                login->postlogin_socket_path);
        } else {
            i_error("write(%s) failed: partial write",
                login->postlogin_socket_path);
        }
        i_close_fd(&fd);
        return -1;
    }
    net_set_nonblock(fd, TRUE);

    pl = i_new(struct master_login_postlogin, 1);
    pl->client = client;
    pl->username = i_strdup(auth_args[0]);
    pl->fd = fd;
    pl->io = io_add(fd, IO_READ, master_login_postlogin_input, pl);
    pl->to = timeout_add(login->postlogin_timeout_secs * 1000,
                 master_login_postlogin_timeout, pl);
    pl->input = str_new(default_pool, 512);
    return 0;
}

static void
master_login_auth_callback(const char *const *auth_args, const char *errormsg,
               void *context)
{
    struct master_login_client *client = context;
    struct master_login_connection *conn = client->conn;
    struct master_auth_reply reply;

    memset(&reply, 0, sizeof(reply));
    reply.tag = client->auth_req.tag;
    reply.status = errormsg == NULL ? MASTER_AUTH_STATUS_OK :
        MASTER_AUTH_STATUS_INTERNAL_ERROR;
    reply.mail_pid = getpid();
    o_stream_nsend(conn->output, &reply, sizeof(reply));

    if (errormsg != NULL || auth_args[0] == NULL) {
        if (auth_args != NULL) {
            i_error("login client: Username missing from auth reply");
            errormsg = MASTER_AUTH_ERRMSG_INTERNAL_FAILURE;
        }
        conn->login->failure_callback(client, errormsg);
        master_login_client_free(&client);
        return;
    }
    i_set_failure_prefix("%s(%s): ", client->conn->login->service->name,
                 auth_args[0]);

    if (conn->login->postlogin_socket_path == NULL)
        master_login_auth_finish(client, auth_args);
    else {
        /* we've sent the reply. the connection is no longer needed,
           so disconnect it (before login process disconnects us and
           logs an error) */
        master_login_conn_close(conn);
        master_login_conn_unref(&conn);

        /* execute post-login scripts before finishing auth */
        if (master_login_postlogin(client, auth_args) < 0)
            master_login_client_free(&client);
    }
}

static void master_login_conn_input(struct master_login_connection *conn)
{
    struct master_auth_request req;
    struct master_login_client *client;
    struct master_login *login = conn->login;
    unsigned char data[MASTER_AUTH_MAX_DATA_SIZE];
    size_t i, session_len = 0;
    int ret, client_fd;

    ret = master_login_conn_read_request(conn, &req, data, &client_fd);
    if (ret <= 0) {
        if (ret < 0) {
            master_login_conn_close(conn);
            master_login_conn_unref(&conn);
        }
        if (client_fd != -1) {
            if (close(client_fd) < 0)
                i_error("close(fd_read client) failed: %m");
        }
        return;
    }
    fd_close_on_exec(client_fd, TRUE);

    /* extract the session ID from the request data */
    for (i = 0; i < req.data_size; i++) {
        if (data[i] == '\0') {
            session_len = i++;
            break;
        }
    }

    /* @UNSAFE: we have a request. do userdb lookup for it. */
    req.data_size -= i;
    client = i_malloc(sizeof(struct master_login_client) + req.data_size);
    client->conn = conn;
    client->fd = client_fd;
    client->auth_req = req;
    client->session_id = i_strndup(data, session_len);
    memcpy(client->data, data+i, req.data_size);
    conn->refcount++;

    master_login_auth_request(login->auth, &req,
                  master_login_auth_callback, client);
}

void master_login_add(struct master_login *login, int fd)
{
    struct master_login_connection *conn;

    conn = i_new(struct master_login_connection, 1);
    conn->refcount = 1;
    conn->login = login;
    conn->fd = fd;
    conn->io = io_add(conn->fd, IO_READ, master_login_conn_input, conn);
    conn->output = o_stream_create_fd(fd, (size_t)-1);
    o_stream_set_no_error_handling(conn->output, TRUE);

    DLLIST_PREPEND(&login->conns, conn);

    /* NOTE: currently there's a separate connection for each request. */
}

static void master_login_conn_close(struct master_login_connection *conn)
{
    if (master_login_conn_is_closed(conn))
        return;

    DLLIST_REMOVE(&conn->login->conns, conn);

    if (conn->io != NULL)
        io_remove(&conn->io);
    o_stream_close(conn->output);
    if (close(conn->fd) < 0)
        i_error("close(master login) failed: %m");
    conn->fd = -1;
}

static void master_login_conn_unref(struct master_login_connection **_conn)
{
    struct master_login_connection *conn = *_conn;

    i_assert(conn->refcount > 0);

    if (--conn->refcount > 0)
        return;

    *_conn = NULL;
    master_login_conn_close(conn);
    o_stream_unref(&conn->output);

    if (!conn->login_success)
        master_service_client_connection_destroyed(conn->login->service);
    i_free(conn);
}

void master_login_stop(struct master_login *login)
{
    login->stopping = TRUE;
    if (master_login_auth_request_count(login->auth) == 0) {
        master_login_auth_disconnect(login->auth);
        master_service_close_config_fd(login->service);
    }
}