/* readconf.c Author: Tatu Ylonen <ylo@cs.hut.fi> Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland All rights reserved Created: Sat Apr 22 00:03:10 1995 ylo Functions for reading the configuration files. */ #include "includes.h" RCSID("$Id: readconf.c,v 1.1 1999/10/27 03:42:44 damien Exp $"); #include "ssh.h" #include "cipher.h" #include "readconf.h" #include "xmalloc.h" /* Format of the configuration file: # Configuration data is parsed as follows: # 1. command line options # 2. user-specific file # 3. system-wide file # Any configuration value is only changed the first time it is set. # Thus, host-specific definitions should be at the beginning of the # configuration file, and defaults at the end. # Host-specific declarations. These may override anything above. A single # host may match multiple declarations; these are processed in the order # that they are given in. Host *.ngs.fi ngs.fi FallBackToRsh no Host fake.com HostName another.host.name.real.org User blaah Port 34289 ForwardX11 no ForwardAgent no Host books.com RemoteForward 9999 shadows.cs.hut.fi:9999 Cipher 3des Host fascist.blob.com Port 23123 User tylonen RhostsAuthentication no PasswordAuthentication no Host puukko.hut.fi User t35124p ProxyCommand ssh-proxy %h %p Host *.fr UseRsh yes Host *.su Cipher none PasswordAuthentication no # Defaults for various options Host * ForwardAgent no ForwardX11 yes RhostsAuthentication yes PasswordAuthentication yes RSAAuthentication yes RhostsRSAAuthentication yes FallBackToRsh no UseRsh no StrictHostKeyChecking yes KeepAlives no IdentityFile ~/.ssh/identity Port 22 EscapeChar ~ */ /* Keyword tokens. */ typedef enum { oForwardAgent, oForwardX11, oGatewayPorts, oRhostsAuthentication, oPasswordAuthentication, oRSAAuthentication, oFallBackToRsh, oUseRsh, #ifdef KRB4 oKerberosAuthentication, #endif /* KRB4 */ #ifdef AFS oKerberosTgtPassing, oAFSTokenPassing, #endif oIdentityFile, oHostName, oPort, oCipher, oRemoteForward, oLocalForward, oUser, oHost, oEscapeChar, oRhostsRSAAuthentication, oProxyCommand, oGlobalKnownHostsFile, oUserKnownHostsFile, oConnectionAttempts, oBatchMode, oCheckHostIP, oStrictHostKeyChecking, oCompression, oCompressionLevel, oKeepAlives, oNumberOfPasswordPrompts, oTISAuthentication, oUsePrivilegedPort } OpCodes; /* Textual representations of the tokens. */ static struct { const char *name; OpCodes opcode; } keywords[] = { { "forwardagent", oForwardAgent }, { "forwardx11", oForwardX11 }, { "gatewayports", oGatewayPorts }, { "useprivilegedport", oUsePrivilegedPort }, { "rhostsauthentication", oRhostsAuthentication }, { "passwordauthentication", oPasswordAuthentication }, { "rsaauthentication", oRSAAuthentication }, #ifdef KRB4 { "kerberosauthentication", oKerberosAuthentication }, #endif /* KRB4 */ #ifdef AFS { "kerberostgtpassing", oKerberosTgtPassing }, { "afstokenpassing", oAFSTokenPassing }, #endif { "fallbacktorsh", oFallBackToRsh }, { "usersh", oUseRsh }, { "identityfile", oIdentityFile }, { "hostname", oHostName }, { "proxycommand", oProxyCommand }, { "port", oPort }, { "cipher", oCipher }, { "remoteforward", oRemoteForward }, { "localforward", oLocalForward }, { "user", oUser }, { "host", oHost }, { "escapechar", oEscapeChar }, { "rhostsrsaauthentication", oRhostsRSAAuthentication }, { "globalknownhostsfile", oGlobalKnownHostsFile }, { "userknownhostsfile", oUserKnownHostsFile }, { "connectionattempts", oConnectionAttempts }, { "batchmode", oBatchMode }, { "checkhostip", oCheckHostIP }, { "stricthostkeychecking", oStrictHostKeyChecking }, { "compression", oCompression }, { "compressionlevel", oCompressionLevel }, { "keepalive", oKeepAlives }, { "numberofpasswordprompts", oNumberOfPasswordPrompts }, { "tisauthentication", oTISAuthentication }, { NULL, 0 } }; /* Characters considered whitespace in strtok calls. */ #define WHITESPACE " \t\r\n" /* Adds a local TCP/IP port forward to options. Never returns if there is an error. */ void add_local_forward(Options *options, int port, const char *host, int host_port) { Forward *fwd; extern uid_t original_real_uid; if ((port & 0xffff) != port) fatal("Requested forwarding of nonexistent port %d.", port); if (port < IPPORT_RESERVED && original_real_uid != 0) fatal("Privileged ports can only be forwarded by root.\n"); if (options->num_local_forwards >= SSH_MAX_FORWARDS_PER_DIRECTION) fatal("Too many local forwards (max %d).", SSH_MAX_FORWARDS_PER_DIRECTION); fwd = &options->local_forwards[options->num_local_forwards++]; fwd->port = port; fwd->host = xstrdup(host); fwd->host_port = host_port; } /* Adds a remote TCP/IP port forward to options. Never returns if there is an error. */ void add_remote_forward(Options *options, int port, const char *host, int host_port) { Forward *fwd; if (options->num_remote_forwards >= SSH_MAX_FORWARDS_PER_DIRECTION) fatal("Too many remote forwards (max %d).", SSH_MAX_FORWARDS_PER_DIRECTION); fwd = &options->remote_forwards[options->num_remote_forwards++]; fwd->port = port; fwd->host = xstrdup(host); fwd->host_port = host_port; } /* Returns the number of the token pointed to by cp of length len. Never returns if the token is not known. */ static OpCodes parse_token(const char *cp, const char *filename, int linenum) { unsigned int i; for (i = 0; keywords[i].name; i++) if (strcmp(cp, keywords[i].name) == 0) return keywords[i].opcode; fatal("%.200s line %d: Bad configuration option.", filename, linenum); /*NOTREACHED*/ return 0; } /* Processes a single option line as used in the configuration files. This only sets those values that have not already been set. */ void process_config_line(Options *options, const char *host, char *line, const char *filename, int linenum, int *activep) { char buf[256], *cp, *string, **charptr; int opcode, *intptr, value, fwd_port, fwd_host_port; /* Skip leading whitespace. */ cp = line + strspn(line, WHITESPACE); if (!*cp || *cp == '\n' || *cp == '#') return; /* Get the keyword. (Each line is supposed to begin with a keyword). */ cp = strtok(cp, WHITESPACE); { char *t = cp; for (; *t != 0; t++) if ('A' <= *t && *t <= 'Z') *t = *t - 'A' + 'a'; /* tolower */ } opcode = parse_token(cp, filename, linenum); switch (opcode) { case oForwardAgent: intptr = &options->forward_agent; parse_flag: cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing yes/no argument.", filename, linenum); value = 0; /* To avoid compiler warning... */ if (strcmp(cp, "yes") == 0 || strcmp(cp, "true") == 0) value = 1; else if (strcmp(cp, "no") == 0 || strcmp(cp, "false") == 0) value = 0; else fatal("%.200s line %d: Bad yes/no argument.", filename, linenum); if (*activep && *intptr == -1) *intptr = value; break; case oForwardX11: intptr = &options->forward_x11; goto parse_flag; case oGatewayPorts: intptr = &options->gateway_ports; goto parse_flag; case oUsePrivilegedPort: intptr = &options->use_privileged_port; goto parse_flag; case oRhostsAuthentication: intptr = &options->rhosts_authentication; goto parse_flag; case oPasswordAuthentication: intptr = &options->password_authentication; goto parse_flag; case oRSAAuthentication: intptr = &options->rsa_authentication; goto parse_flag; case oRhostsRSAAuthentication: intptr = &options->rhosts_rsa_authentication; goto parse_flag; #ifdef KRB4 case oKerberosAuthentication: intptr = &options->kerberos_authentication; goto parse_flag; #endif /* KRB4 */ #ifdef AFS case oKerberosTgtPassing: intptr = &options->kerberos_tgt_passing; goto parse_flag; case oAFSTokenPassing: intptr = &options->afs_token_passing; goto parse_flag; #endif case oFallBackToRsh: intptr = &options->fallback_to_rsh; goto parse_flag; case oUseRsh: intptr = &options->use_rsh; goto parse_flag; case oBatchMode: intptr = &options->batch_mode; goto parse_flag; case oCheckHostIP: intptr = &options->check_host_ip; goto parse_flag; case oStrictHostKeyChecking: intptr = &options->strict_host_key_checking; cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing yes/no argument.", filename, linenum); value = 0; /* To avoid compiler warning... */ if (strcmp(cp, "yes") == 0 || strcmp(cp, "true") == 0) value = 1; else if (strcmp(cp, "no") == 0 || strcmp(cp, "false") == 0) value = 0; else if (strcmp(cp, "ask") == 0) value = 2; else fatal("%.200s line %d: Bad yes/no/ask argument.", filename, linenum); if (*activep && *intptr == -1) *intptr = value; break; case oCompression: intptr = &options->compression; goto parse_flag; case oKeepAlives: intptr = &options->keepalives; goto parse_flag; case oNumberOfPasswordPrompts: intptr = &options->number_of_password_prompts; goto parse_int; case oTISAuthentication: cp = strtok(NULL, WHITESPACE); if (cp != 0 && (strcmp(cp, "yes") == 0 || strcmp(cp, "true") == 0)) fprintf(stderr, "%.99s line %d: Warning, TIS is not supported.\n", filename, linenum); break; case oCompressionLevel: intptr = &options->compression_level; goto parse_int; case oIdentityFile: cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing argument.", filename, linenum); if (*activep) { if (options->num_identity_files >= SSH_MAX_IDENTITY_FILES) fatal("%.200s line %d: Too many identity files specified (max %d).", filename, linenum, SSH_MAX_IDENTITY_FILES); options->identity_files[options->num_identity_files++] = xstrdup(cp); } break; case oUser: charptr = &options->user; parse_string: cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing argument.", filename, linenum); if (*activep && *charptr == NULL) *charptr = xstrdup(cp); break; case oGlobalKnownHostsFile: charptr = &options->system_hostfile; goto parse_string; case oUserKnownHostsFile: charptr = &options->user_hostfile; goto parse_string; case oHostName: charptr = &options->hostname; goto parse_string; case oProxyCommand: charptr = &options->proxy_command; string = xstrdup(""); while ((cp = strtok(NULL, WHITESPACE)) != NULL) { string = xrealloc(string, strlen(string) + strlen(cp) + 2); strcat(string, " "); strcat(string, cp); } if (*activep && *charptr == NULL) *charptr = string; else xfree(string); return; case oPort: intptr = &options->port; parse_int: cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing argument.", filename, linenum); if (cp[0] < '0' || cp[0] > '9') fatal("%.200s line %d: Bad number.", filename, linenum); #if 0 value = atoi(cp); #else { char *ptr; value = strtol(cp, &ptr, 0); /* Octal, decimal, or hex format? */ if (cp == ptr) fatal("%.200s line %d: Bad number.", filename, linenum); } #endif if (*activep && *intptr == -1) *intptr = value; break; case oConnectionAttempts: intptr = &options->connection_attempts; goto parse_int; case oCipher: intptr = &options->cipher; cp = strtok(NULL, WHITESPACE); value = cipher_number(cp); if (value == -1) fatal("%.200s line %d: Bad cipher.", filename, linenum); if (*activep && *intptr == -1) *intptr = value; break; case oRemoteForward: cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing argument.", filename, linenum); if (cp[0] < '0' || cp[0] > '9') fatal("%.200s line %d: Badly formatted port number.", filename, linenum); fwd_port = atoi(cp); cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing second argument.", filename, linenum); if (sscanf(cp, "%255[^:]:%d", buf, &fwd_host_port) != 2) fatal("%.200s line %d: Badly formatted host:port.", filename, linenum); if (*activep) add_remote_forward(options, fwd_port, buf, fwd_host_port); break; case oLocalForward: cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing argument.", filename, linenum); if (cp[0] < '0' || cp[0] > '9') fatal("%.200s line %d: Badly formatted port number.", filename, linenum); fwd_port = atoi(cp); cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing second argument.", filename, linenum); if (sscanf(cp, "%255[^:]:%d", buf, &fwd_host_port) != 2) fatal("%.200s line %d: Badly formatted host:port.", filename, linenum); if (*activep) add_local_forward(options, fwd_port, buf, fwd_host_port); break; case oHost: *activep = 0; while ((cp = strtok(NULL, WHITESPACE)) != NULL) if (match_pattern(host, cp)) { debug("Applying options for %.100s", cp); *activep = 1; break; } /* Avoid garbage check below, as strtok already returned NULL. */ return; case oEscapeChar: intptr = &options->escape_char; cp = strtok(NULL, WHITESPACE); if (!cp) fatal("%.200s line %d: Missing argument.", filename, linenum); if (cp[0] == '^' && cp[2] == 0 && (unsigned char)cp[1] >= 64 && (unsigned char)cp[1] < 128) value = (unsigned char)cp[1] & 31; else if (strlen(cp) == 1) value = (unsigned char)cp[0]; else if (strcmp(cp, "none") == 0) value = -2; else { fatal("%.200s line %d: Bad escape character.", filename, linenum); /*NOTREACHED*/ value = 0; /* Avoid compiler warning. */ } if (*activep && *intptr == -1) *intptr = value; break; default: fatal("parse_config_file: Unimplemented opcode %d", opcode); } /* Check that there is no garbage at end of line. */ if (strtok(NULL, WHITESPACE) != NULL) fatal("%.200s line %d: garbage at end of line.", filename, linenum); } /* Reads the config file and modifies the options accordingly. Options should already be initialized before this call. This never returns if there is an error. If the file does not exist, this returns immediately. */ void read_config_file(const char *filename, const char *host, Options *options) { FILE *f; char line[1024]; int active, linenum; /* Open the file. */ f = fopen(filename, "r"); if (!f) return; debug("Reading configuration data %.200s", filename); /* Mark that we are now processing the options. This flag is turned on/off by Host specifications. */ active = 1; linenum = 0; while (fgets(line, sizeof(line), f)) { /* Update line number counter. */ linenum++; process_config_line(options, host, line, filename, linenum, &active); } fclose(f); } /* Initializes options to special values that indicate that they have not yet been set. Read_config_file will only set options with this value. Options are processed in the following order: command line, user config file, system config file. Last, fill_default_options is called. */ void initialize_options(Options *options) { memset(options, 'X', sizeof(*options)); options->forward_agent = -1; options->forward_x11 = -1; options->gateway_ports = -1; options->use_privileged_port = -1; options->rhosts_authentication = -1; options->rsa_authentication = -1; #ifdef KRB4 options->kerberos_authentication = -1; #endif #ifdef AFS options->kerberos_tgt_passing = -1; options->afs_token_passing = -1; #endif options->password_authentication = -1; options->rhosts_rsa_authentication = -1; options->fallback_to_rsh = -1; options->use_rsh = -1; options->batch_mode = -1; options->check_host_ip = -1; options->strict_host_key_checking = -1; options->compression = -1; options->keepalives = -1; options->compression_level = -1; options->port = -1; options->connection_attempts = -1; options->number_of_password_prompts = -1; options->cipher = -1; options->num_identity_files = 0; options->hostname = NULL; options->proxy_command = NULL; options->user = NULL; options->escape_char = -1; options->system_hostfile = NULL; options->user_hostfile = NULL; options->num_local_forwards = 0; options->num_remote_forwards = 0; } /* Called after processing other sources of option data, this fills those options for which no value has been specified with their default values. */ void fill_default_options(Options *options) { if (options->forward_agent == -1) options->forward_agent = 1; if (options->forward_x11 == -1) options->forward_x11 = 1; if (options->gateway_ports == -1) options->gateway_ports = 0; if (options->use_privileged_port == -1) options->use_privileged_port = 1; if (options->rhosts_authentication == -1) options->rhosts_authentication = 1; if (options->rsa_authentication == -1) options->rsa_authentication = 1; #ifdef KRB4 if (options->kerberos_authentication == -1) options->kerberos_authentication = 1; #endif /* KRB4 */ #ifdef AFS if (options->kerberos_tgt_passing == -1) options->kerberos_tgt_passing = 1; if (options->afs_token_passing == -1) options->afs_token_passing = 1; #endif /* AFS */ if (options->password_authentication == -1) options->password_authentication = 1; if (options->rhosts_rsa_authentication == -1) options->rhosts_rsa_authentication = 1; if (options->fallback_to_rsh == -1) options->fallback_to_rsh = 1; if (options->use_rsh == -1) options->use_rsh = 0; if (options->batch_mode == -1) options->batch_mode = 0; if (options->check_host_ip == -1) options->check_host_ip = 1; if (options->strict_host_key_checking == -1) options->strict_host_key_checking = 2; /* 2 is default */ if (options->compression == -1) options->compression = 0; if (options->keepalives == -1) options->keepalives = 1; if (options->compression_level == -1) options->compression_level = 6; if (options->port == -1) options->port = 0; /* Filled in ssh_connect. */ if (options->connection_attempts == -1) options->connection_attempts = 4; if (options->number_of_password_prompts == -1) options->number_of_password_prompts = 3; if (options->cipher == -1) options->cipher = SSH_CIPHER_NOT_SET; /* Selected in ssh_login(). */ if (options->num_identity_files == 0) { options->identity_files[0] = xmalloc(2 + strlen(SSH_CLIENT_IDENTITY) + 1); sprintf(options->identity_files[0], "~/%.100s", SSH_CLIENT_IDENTITY); options->num_identity_files = 1; } if (options->escape_char == -1) options->escape_char = '~'; if (options->system_hostfile == NULL) options->system_hostfile = SSH_SYSTEM_HOSTFILE; if (options->user_hostfile == NULL) options->user_hostfile = SSH_USER_HOSTFILE; /* options->proxy_command should not be set by default */ /* options->user will be set in the main program if appropriate */ /* options->hostname will be set in the main program if appropriate */ }