proto_control_unix.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: f76145658fe4765af75814a5420b7505f7cb7f8b $
 * @file proto_control_unix.c
 * @brief Control handler for Unix sockets.
 *
 * @copyright 2018 The FreeRADIUS server project.
 * @copyright 2018 Alan DeKok (aland@deployingradius.com)
 */
#include <freeradius-devel/server/main_config.h>
 
#include <freeradius-devel/io/application.h>
#include <freeradius-devel/io/listen.h>
#include <freeradius-devel/io/schedule.h>
#include <freeradius-devel/server/protocol.h>
#include <freeradius-devel/util/perm.h>
#include <freeradius-devel/util/trie.h>
#include <freeradius-devel/util/file.h>
 
#include <netdb.h>
 
#include "proto_control.h"
 
#include <freeradius-devel/bio/fd.h>
 
#ifdef HAVE_SYS_STAT_H
#endif
 
#include <fcntl.h>
#include <libgen.h>
 
typedef struct {
        char const                      *name;                  //!< socket name
 
        int                             sockfd;
 
        fr_bio_t                        *fd_bio;
 
        fr_stats_t                      stats;                  //!< statistics for this socket
 
        fr_io_address_t                 *connection;            //!< for connected sockets.
 
 
        fr_io_data_read_t               read;                   //!< function to process data *after* reading
        FILE                            *stdout_fp;
        FILE                            *stderr_fp;
 
        fr_conduit_type_t               misc_conduit;
        FILE                            *misc;
        fr_cmd_info_t                   *info;                  //!< for running commands
 
        fr_client_t                     radclient;              //!< for faking out clients
} proto_control_unix_thread_t;
 
typedef struct {
        CONF_SECTION                    *cs;                    //!< our configuration
 
        char const                      *filename;              //!< filename of control socket
        char const                      *uid_name;              //!< name of UID to require
        char const                      *gid_name;              //!< name of GID to require
        uid_t                           uid;                    //!< UID value
        gid_t                           gid;                    //!< GID value
 
        uint32_t                        recv_buff;              //!< How big the kernel's receive buffer should be.
 
        uint32_t                        max_packet_size;        //!< for message ring buffer.
 
        char const                      *mode_name;
        bool                            read_only;
 
        bool                            recv_buff_is_set;       //!< Whether we were provided with a receive
                                                                //!< buffer value.
        char const                      *peer_uid_name;         //!< name of UID to require
        char const                      *peer_gid_name;         //!< name of GID to require
        uid_t                           peer_uid;               //!< UID value
        gid_t                           peer_gid;               //!< GID value
 
} proto_control_unix_t;
 
static const conf_parser_t peercred_config[] = {
        { FR_CONF_OFFSET("uid", proto_control_unix_t, peer_uid_name) },
        { FR_CONF_OFFSET("gid", proto_control_unix_t, peer_gid_name) },
 
        CONF_PARSER_TERMINATOR
};
 
static const conf_parser_t unix_listen_config[] = {
        { FR_CONF_OFFSET_FLAGS("filename", CONF_FLAG_REQUIRED, proto_control_unix_t, filename),
        .dflt = "${run_dir}/radiusd.sock}" },
        { FR_CONF_OFFSET("uid", proto_control_unix_t, uid_name) },
        { FR_CONF_OFFSET("gid", proto_control_unix_t, gid_name) },
        { FR_CONF_OFFSET("mode", proto_control_unix_t, mode_name) },
 
        { FR_CONF_OFFSET_IS_SET("recv_buff", FR_TYPE_UINT32, 0, proto_control_unix_t, recv_buff) },
 
        { FR_CONF_OFFSET("max_packet_size", proto_control_unix_t, max_packet_size), .dflt = "4096" } ,
 
        { FR_CONF_POINTER("peercred", 0, CONF_FLAG_SUBSECTION, NULL), .subcs = (void const *) peercred_config },
 
        CONF_PARSER_TERMINATOR
};
 
#define FR_READ  (1)
#define FR_WRITE (2)
 
static fr_table_num_sorted_t mode_names[] = {
        { L("read-only"),               FR_READ                 },
        { L("read-write"),              FR_READ | FR_WRITE      },
        { L("ro"),                      FR_READ                 },
        { L("rw"),                      FR_READ | FR_WRITE      }
};
static size_t mode_names_len = NUM_ELEMENTS(mode_names);
 
#undef INT
#define INT size_t
#define SINT ssize_t
 
static SINT write_stdout(void *instance, char const *buffer, INT buffer_size)
{
        proto_control_unix_thread_t *thread = talloc_get_type_abort(instance, proto_control_unix_thread_t);
 
        return fr_conduit_write(thread->sockfd, FR_CONDUIT_STDOUT, buffer, buffer_size);
}
 
static SINT write_stderr(void *instance, char const *buffer, INT buffer_size)
{
        proto_control_unix_thread_t *thread = talloc_get_type_abort(instance, proto_control_unix_thread_t)
;
        return fr_conduit_write(thread->sockfd, FR_CONDUIT_STDERR, buffer, buffer_size);
}
 
static SINT write_misc(void *instance, char const *buffer, INT buffer_size)
{
        proto_control_unix_thread_t *thread = talloc_get_type_abort(instance, proto_control_unix_thread_t);
 
        return fr_conduit_write(thread->sockfd, thread->misc_conduit, buffer, buffer_size);
}
 
 
/*
 *      Run a command.
 */
static ssize_t mod_read_command(fr_listen_t *li, UNUSED void **packet_ctx, UNUSED fr_time_t *recv_time_p, uint8_t *buffer, UNUSED size_t buffer_len, UNUSED size_t *leftover)
{
        proto_control_unix_t const      *inst = talloc_get_type_abort_const(li->app_io_instance, proto_control_unix_t);
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
        fr_conduit_hdr_t                *hdr = (fr_conduit_hdr_t *) buffer;
        uint32_t                        status;
        uint8_t                         *cmd = buffer + sizeof(*hdr);
        int                             rcode;
        char                            string[1024];
 
        hdr->length = ntohl(hdr->length);
        if (hdr->length >= sizeof(string)) goto fail;
 
        /*
         *      If the write gives us nothing, send an empty SUCCESS back.
         */
        if (!hdr->length) {
                status = FR_CONDUIT_SUCCESS;
                goto done;
        }
 
        /*
         *      fr_command_run() expects a zero-terminated string...
         */
        memcpy(string, cmd, hdr->length);
        string[hdr->length] = '\0';
 
        /*
         *      Content is the string we need help for.
         */
        if (htons(hdr->conduit) == FR_CONDUIT_HELP) {
                fr_radmin_help(thread->stdout_fp, string);
                // @todo - have in-band signalling saying that the help is done?
                // we want to be able to say that *this* help is done.
                // the best way to do that is to have a token, and every command
                // from the other end sends a token, and we echo it back here...
                // Or, since we currently can't do streaming commands, it's OK?
                // Or, we assume that origin 0 is for interactive commands,
                // and that the other origins are for streaming output...
                status = FR_CONDUIT_SUCCESS;
                goto done;
        }
 
        if (htons(hdr->conduit) == FR_CONDUIT_COMPLETE) {
                uint16_t start;
 
                if (hdr->length < 2) goto fail;
 
                start = (string[0] << 8) | string[1];
 
                thread->misc_conduit = FR_CONDUIT_COMPLETE;
 
                fr_radmin_complete(thread->misc, string + 2, start);
                thread->misc_conduit = FR_CONDUIT_STDOUT;
                status = FR_CONDUIT_SUCCESS;
                goto done;
        }
 
        if (htons(hdr->conduit) != FR_CONDUIT_STDIN) {
                DEBUG("ERROR: Ignoring data which is from wrong input");
                return 0;
        }
 
        DEBUG("radmin-remote> %.*s", (int) hdr->length, cmd);
 
        rcode = fr_radmin_run(thread->info, thread->stdout_fp, thread->stderr_fp, string, inst->read_only);
        if (rcode < 0) {
fail:
                status = FR_CONDUIT_FAIL;
 
        } else if (rcode == 0) {
                /*
                 *      The other end should keep track of it's
                 *      context, and send us full lines.
                 */
                (void) fr_command_clear(0, thread->info);
                status = FR_CONDUIT_PARTIAL;
        } else {
                status = FR_CONDUIT_SUCCESS;
        }
 
done:
        status = htonl(status);
        (void) fr_conduit_write(thread->sockfd, FR_CONDUIT_CMD_STATUS, &status, sizeof(status));
 
        return 0;
}
 
/*
 *      Process an initial connection request.
 */
static ssize_t mod_read_init(fr_listen_t *li, UNUSED void **packet_ctx, UNUSED fr_time_t *recv_time_p, uint8_t *buffer, size_t buffer_len, UNUSED size_t *leftover)
{
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
        fr_conduit_hdr_t                *hdr = (fr_conduit_hdr_t *) buffer;
        uint32_t                        magic;
 
        if (htons(hdr->conduit) != FR_CONDUIT_INIT_ACK) {
                DEBUG("ERROR: Connection is missing initial ACK packet.");
                return -1;
        }
 
        if (buffer_len < sizeof(*hdr)) {
                DEBUG("ERROR: Initial ACK is malformed");
                return -1;
        }
 
        if (htonl(hdr->length) != 8) {
                DEBUG("ERROR: Initial ACK has wrong length (%lu).", (size_t) htonl(hdr->length));
                return -1;
        }
 
        memcpy(&magic, buffer + sizeof(*hdr), sizeof(magic));
        magic = htonl(magic);
        if (magic != FR_CONDUIT_MAGIC) {
                DEBUG("ERROR: Connection from incompatible version of radmin.");
                return -1;
        }
 
        /*
         *      Next 4 bytes are zero, we ignore them.
         */
        if (write(thread->sockfd, buffer, buffer_len) < (ssize_t) buffer_len) {
                DEBUG("ERROR: Blocking write to socket... oops");
                return -1;
        }
 
        thread->read = mod_read_command;
 
        return 0;
}
 
static ssize_t mod_read(fr_listen_t *li, void **packet_ctx, fr_time_t *recv_time_p, uint8_t *buffer, size_t buffer_len, size_t *leftover)
{
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
        ssize_t                         data_size;
 
        fr_conduit_type_t               conduit;
        bool                            want_more;
 
        /*
         *      Read data into the buffer.
         */
        data_size = fr_conduit_read_async(thread->sockfd, &conduit, buffer, buffer_len, leftover, &want_more);
        if (data_size < 0) {
                DEBUG2("proto_control_unix got read error %zd: %s", data_size, fr_syserror(errno));
                return data_size;
        }
 
        /*
         *      Note that we return ERROR for all bad packets, as
         *      there's no point in reading packets from a TCP
         *      connection which isn't sending us properly formatted
         *      packets.
         */
 
        /*
         *      Not enough for a full packet, ask the caller to read more.
         */
        if (want_more) {
                return 0;
        }
 
        // @todo - maybe convert timestamp?
        *recv_time_p = fr_time();
        *leftover = 0;
 
        /*
         *      Print out what we received.
         */
        DEBUG3("proto_control_unix - Received command packet length %d on %s",
               (int) data_size, thread->name);
 
        /*
         *      Run the state machine to process the rest of the packet.
         */
        return thread->read(li, packet_ctx, recv_time_p, buffer, (size_t) data_size, leftover);
}
 
 
static ssize_t mod_write(fr_listen_t *li, UNUSED void *packet_ctx, UNUSED fr_time_t request_time,
                         uint8_t *buffer, size_t buffer_len, size_t written)
{
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
        ssize_t                         data_size;
 
        /*
         *      @todo - share a stats interface with the parent?  or
         *      put the stats in the listener, so that proto_control
         *      can update them, too.. <sigh>
         */
        thread->stats.total_responses++;
 
        /*
         *      Only write replies if they're RADIUS packets.
         *      sometimes we want to NOT send a reply...
         */
        data_size = write(thread->sockfd, buffer + written, buffer_len - written);
 
        /*
         *      This socket is dead.  That's an error...
         */
        if (data_size <= 0) return data_size;
 
#ifdef __COVERITY__
        /*
         *      data_size and written have type size_t, so
         *      their sum can at least in theory exceed SSIZE_MAX.
         *      We add this check to placate Coverity.
         *
         *      When Coverity examines this function it doesn't have
         *      the caller context to see that it's honoring needed
         *      preconditions (buffer_len <=SSIZE_MAX, and the loop
         *      schema needed to use this function).
         */
        if (data_size + written > SSIZE_MAX) return -1;
#endif
 
        return data_size + written;
}
 
 
static int mod_connection_set(fr_listen_t *li, fr_io_address_t *connection)
{
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
 
        thread->connection = connection;
 
        // @todo - set name to path + peer ID of other end?
 
        return 0;
}
 
static void mod_network_get(int *ipproto, bool *dynamic_clients, fr_trie_t const **trie, UNUSED void *instance)
{
        *ipproto = IPPROTO_TCP;
        *dynamic_clients = false;
        *trie = NULL;
}
 
/** Open a UNIX listener for control sockets
 *
 */
static int mod_open(fr_listen_t *li)
{
        proto_control_unix_t const      *inst = talloc_get_type_abort_const(li->app_io_instance, proto_control_unix_t);
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
 
        CONF_ITEM                       *ci;
        CONF_SECTION                    *server_cs;
 
        fr_bio_fd_info_t const          *info;
        fr_bio_fd_config_t              cfg;
 
        fr_assert(!thread->connection);
 
        cfg = (fr_bio_fd_config_t) {
                .type = FR_BIO_FD_LISTEN,
                .socket_type = SOCK_STREAM,
                .path = inst->filename,
                .uid = inst->uid,
                .gid = inst->gid,
                .perm = 0x700,
                .async = true,
        };
 
        thread->fd_bio = fr_bio_fd_alloc(thread, &cfg, 0);
        if (!thread->fd_bio) {
                PERROR("Failed allocating UNIX path %s", inst->filename);
                return -1;
        }
 
        info = fr_bio_fd_info(thread->fd_bio);
        fr_assert(info != NULL);
 
        li->fd = thread->sockfd = info->socket.fd;
 
        ci = cf_parent(inst->cs); /* listen { ... } */
        fr_assert(ci != NULL);
        ci = cf_parent(ci);
        fr_assert(ci != NULL);
 
        server_cs = cf_item_to_section(ci);
 
        thread->name = talloc_typed_asprintf(thread, "control_unix from filename %s", inst->filename);
 
        /*
         *      Set up the fake client
         */
        thread->radclient.longname = inst->filename;
        thread->radclient.ipaddr.af = AF_INET;
        thread->radclient.src_ipaddr.af = AF_INET;
 
        thread->radclient.server_cs = server_cs;
        fr_assert(thread->radclient.server_cs != NULL);
        thread->radclient.server = cf_section_name2(thread->radclient.server_cs);
 
        return 0;
}
 
#if !defined(HAVE_GETPEEREID) && defined(SO_PEERCRED)
static int getpeereid(int s, uid_t *euid, gid_t *egid)
{
        struct ucred cr;
        socklen_t cl = sizeof(cr);
 
        if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cl) < 0) {
                return -1;
        }
 
        *euid = cr.uid;
        *egid = cr.gid;
        return 0;
}
 
/* we now have getpeereid() in this file */
#define HAVE_GETPEEREID (1)
 
#endif /* HAVE_GETPEEREID */
 
static int _close_cookies(proto_control_unix_thread_t *thread)
{
        if (thread->stdout_fp) fclose(thread->stdout_fp);
        if (thread->stderr_fp) fclose(thread->stderr_fp);
        if (thread->misc) fclose(thread->misc);
 
        return 0;
}
 
/** Set the file descriptor for this socket.
 *
 */
static int mod_fd_set(fr_listen_t *li, int fd)
{
        proto_control_unix_t const      *inst = talloc_get_type_abort_const(li->app_io_instance, proto_control_unix_t);
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
 
        cookie_io_functions_t io;
 
#ifdef HAVE_GETPEEREID
        /*
         *      Perform user authentication.
         *
         *      @todo - this really belongs in the accept() callback,
         *      so that we don't create an entirely new listener and
         *      then close it.
         */
        if (inst->peer_uid || inst->peer_gid) {
                uid_t uid;
                gid_t gid;
 
                if (getpeereid(fd, &uid, &gid) < 0) {
                        ERROR("Failed getting peer credentials for %s: %s",
                              inst->filename, fr_syserror(errno));
                        return -1;
                }
 
                /*
                 *      Only do UID checking if the caller is
                 *      non-root.  The superuser can do anything, so
                 *      we might as well let them do anything.
                 */
                if (uid != 0) do {
                                /*
                                 *      Allow entry if UID or GID matches.
                                 */
                                if (inst->peer_uid_name && (inst->peer_uid == uid)) break;
                                if (inst->peer_gid_name && (inst->peer_gid == gid)) break;
 
                                if (inst->peer_uid_name && (inst->peer_uid != uid)) {
                                        ERROR("Unauthorized connection to %s from uid %ld",
                                              inst->filename, (long int) uid);
                                        return -1;
                                }
 
                                if (inst->peer_gid_name && (inst->peer_gid != gid)) {
                                        ERROR("Unauthorized connection to %s from gid %ld",
                                              inst->filename, (long int) gid);
                                        return -1;
                                }
 
                        } while (0);
 
                thread->name = talloc_typed_asprintf(thread, "proto unix filename %s from peer UID %u GID %u",
                                                     inst->filename,
                                                     (unsigned int) uid, (unsigned int) gid);
        } else
#endif
 
 
        thread->name = talloc_typed_asprintf(thread, "proto unix filename %s", inst->filename);
 
        thread->sockfd = fd;
        thread->read = mod_read_init;
 
        /*
         *      These must be set separately as they have different prototypes.
         */
        io.read = NULL;
        io.seek = NULL;
        io.close = NULL;
        io.write = write_stdout;
 
        thread->stdout_fp = fopencookie(thread, "w", io);
 
        io.write = write_stderr;
        thread->stderr_fp = fopencookie(thread, "w", io);
 
        io.write = write_misc;
        thread->misc = fopencookie(thread, "w", io);
 
        talloc_set_destructor(thread, _close_cookies);
 
        /*
         *      @todo - if we move to a binary protocol, then we
         *      should change this to a small (i.e. 1K) buffer.  The
         *      data should be sent over to the remote side as quickly
         *      as possible.
         */
        (void) setvbuf(thread->stdout_fp, NULL, _IOLBF, 0);
        (void) setvbuf(thread->stderr_fp, NULL, _IOLBF, 0);
        (void) setvbuf(thread->misc, NULL, _IOLBF, 0);
 
        thread->info = talloc_zero(thread, fr_cmd_info_t);
        fr_command_info_init(thread, thread->info);
 
        return 0;
}
 
static char const *mod_name(fr_listen_t *li)
{
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
 
        return thread->name;
}
 
 
static int mod_instantiate(module_inst_ctx_t const *mctx)
{
        proto_control_unix_t    *inst = talloc_get_type_abort(mctx->mi->data, proto_control_unix_t);
        CONF_SECTION            *conf = mctx->mi->conf;
 
        inst->cs = conf;
 
        if (inst->recv_buff_is_set) {
                FR_INTEGER_BOUND_CHECK("recv_buff", inst->recv_buff, >=, 32);
                FR_INTEGER_BOUND_CHECK("recv_buff", inst->recv_buff, <=, INT_MAX);
        }
 
        if (inst->uid_name) {
                struct passwd *pwd;
 
                if (fr_perm_getpwnam(conf, &pwd, inst->uid_name) < 0) {
                        PERROR("Failed getting uid for %s", inst->uid_name);
                        return -1;
                }
                inst->uid = pwd->pw_uid;
                talloc_free(pwd);
 
        } else if (main_config->server_uid) {
                inst->uid = main_config->server_uid;
 
        } else {
                inst->uid = getuid();
        }
 
        if (inst->gid_name) {
                if (fr_perm_gid_from_str(conf, &inst->gid, inst->gid_name) < 0) {
                        PERROR("Failed getting gid for %s", inst->gid_name);
                        return -1;
                }
 
        } else if (main_config->server_gid) {
                inst->gid = main_config->server_gid;
 
        } else {
                inst->gid = getgid();
        }
 
        /*
         *      And for peer creds
         */
        if (inst->peer_uid_name) {
                struct passwd *pwd;
 
                if (fr_perm_getpwnam(conf, &pwd, inst->peer_uid_name) < 0) {
                        PERROR("Failed getting peer uid for %s", inst->peer_uid_name);
                        return -1;
                }
                inst->peer_uid = pwd->pw_uid;
                talloc_free(pwd);
        }
 
        if (inst->peer_gid_name) {
                if (fr_perm_gid_from_str(conf, &inst->peer_gid, inst->peer_gid_name) < 0) {
                        PERROR("Failed getting peer gid for %s", inst->peer_gid_name);
                        return -1;
                }
        }
 
        if (!inst->mode_name) {
                inst->read_only = true;
        } else {
                int mode;
 
                mode = fr_table_value_by_str(mode_names, inst->mode_name, 0);
                if (!mode) {
                        ERROR("Invalid mode name \"%s\"",
                              inst->mode_name);
                        return -1;
                }
 
                if ((mode & FR_WRITE) == 0) {
                        inst->read_only = true;
                } else {
                        inst->read_only = false;
                }
        }
 
        FR_INTEGER_BOUND_CHECK("max_packet_size", inst->max_packet_size, >=, 20);
        FR_INTEGER_BOUND_CHECK("max_packet_size", inst->max_packet_size, <=, 65536);
 
        return 0;
}
 
static fr_client_t *mod_client_find(fr_listen_t *li, UNUSED fr_ipaddr_t const *ipaddr, UNUSED int ipproto)
{
        proto_control_unix_thread_t     *thread = talloc_get_type_abort(li->thread_instance, proto_control_unix_thread_t);
 
        return &thread->radclient;
}
 
extern fr_app_io_t proto_control_unix;
fr_app_io_t proto_control_unix = {
        .common = {
                .magic                  = MODULE_MAGIC_INIT,
                .name                   = "control_unix",
                .config                 = unix_listen_config,
                .inst_size              = sizeof(proto_control_unix_t),
                .thread_inst_size       = sizeof(proto_control_unix_thread_t),
                .instantiate            = mod_instantiate
        },
        .default_message_size   = 4096,
 
        .open                   = mod_open,
        .read                   = mod_read,
        .write                  = mod_write,
        .fd_set                 = mod_fd_set,
        .connection_set         = mod_connection_set,
        .network_get            = mod_network_get,
        .client_find            = mod_client_find,
        .get_name               = mod_name,
};