add a sshd_config PamServiceName option

Allows selecting which PAM service name to use when UsePAM is
enabled. Defaults to "sshd" unless overridden at compile time
by defining SSHD_PAM_SERVICE.

bz2102, ok dtucker@

auth-pam.c

@@ -67,10 +67,6 @@
 #include <pam/pam_appl.h>
 #endif
 
-#if !defined(SSHD_PAM_SERVICE)
-# define SSHD_PAM_SERVICE		"sshd"
-#endif
-
 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
 #ifdef PAM_SUN_CODEBASE
 # define sshpam_const		/* Solaris, HP-UX, SunOS */
@@ -693,6 +689,8 @@ sshpam_init(struct ssh *ssh, Authctxt *authctxt)
 	const char **ptr_pam_user = &pam_user;
 	int r;
 
+	if (options.pam_service_name == NULL)
+		fatal_f("internal error: NULL PAM service name");
 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE)
 	/* Protect buggy PAM implementations from excessively long usernames */
 	if (strlen(user) >= PAM_MAX_RESP_SIZE)
@@ -714,9 +712,10 @@ sshpam_init(struct ssh *ssh, Authctxt *authctxt)
 		pam_end(sshpam_handle, sshpam_err);
 		sshpam_handle = NULL;
 	}
-	debug("PAM: initializing for \"%s\"", user);
+	debug("PAM: initializing for \"%s\" with service \"%s\"", user,
-	sshpam_err =
+	    options.pam_service_name);
-	    pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
+	sshpam_err = pam_start(options.pam_service_name, user,
+	    &store_conv, &sshpam_handle);
 	sshpam_authctxt = authctxt;
 
 	if (sshpam_err != PAM_SUCCESS) {

servconf.c

@@ -69,6 +69,10 @@
 #include "myproposal.h"
 #include "digest.h"
 
+#if !defined(SSHD_PAM_SERVICE)
+# define SSHD_PAM_SERVICE		"sshd"
+#endif
+
 static void add_listen_addr(ServerOptions *, const char *,
     const char *, int);
 static void add_one_listen_addr(ServerOptions *, const char *,
@@ -88,6 +92,7 @@ initialize_server_options(ServerOptions *options)
 
 	/* Portable-specific options */
 	options->use_pam = -1;
+	options->pam_service_name = NULL;
 
 	/* Standard Options */
 	options->num_ports = 0;
@@ -291,6 +296,8 @@ fill_default_server_options(ServerOptions *options)
 	/* Portable-specific options */
 	if (options->use_pam == -1)
 		options->use_pam = 0;
+	if (options->pam_service_name == NULL)
+		options->pam_service_name = xstrdup(SSHD_PAM_SERVICE);
 
 	/* Standard Options */
 	if (options->num_host_key_files == 0) {
@@ -530,7 +537,7 @@ fill_default_server_options(ServerOptions *options)
 typedef enum {
 	sBadOption,		/* == unknown option */
 	/* Portable-specific options */
-	sUsePAM,
+	sUsePAM, sPAMServiceName,
 	/* Standard Options */
 	sPort, sHostKeyFile, sLoginGraceTime,
 	sPermitRootLogin, sLogFacility, sLogLevel, sLogVerbose,
@@ -583,8 +590,10 @@ static struct {
 	/* Portable-specific options */
 #ifdef USE_PAM
 	{ "usepam", sUsePAM, SSHCFG_GLOBAL },
+	{ "pamservicename", sPAMServiceName, SSHCFG_ALL },
 #else
 	{ "usepam", sUnsupported, SSHCFG_GLOBAL },
+	{ "pamservicename", sUnsupported, SSHCFG_ALL },
 #endif
 	{ "pamauthenticationviakbdint", sDeprecated, SSHCFG_GLOBAL },
 	/* Standard Options */
@@ -1318,6 +1327,16 @@ process_server_config_line_depth(ServerOptions *options, char *line,
 	case sUsePAM:
 		intptr = &options->use_pam;
 		goto parse_flag;
+	case sPAMServiceName:
+		charptr = &options->pam_service_name;
+		arg = argv_next(&ac, &av);
+		if (!arg || *arg == '\0') {
+			fatal("%s line %d: missing argument.",
+			    filename, linenum);
+		}
+		if (*activep && *charptr == NULL)
+			*charptr = xstrdup(arg);
+		break;
 
 	/* Standard Options */
 	case sBadOption:
@@ -3128,6 +3147,7 @@ dump_config(ServerOptions *o)
 	/* integer arguments */
 #ifdef USE_PAM
 	dump_cfg_fmtint(sUsePAM, o->use_pam);
+	dump_cfg_string(sPAMServiceName, o->pam_service_name);
 #endif
 	dump_cfg_int(sLoginGraceTime, o->login_grace_time);
 	dump_cfg_int(sX11DisplayOffset, o->x11_display_offset);

servconf.h

@@ -210,6 +210,7 @@ typedef struct {
 	char   *adm_forced_command;
 
 	int	use_pam;		/* Enable auth via PAM */
+	char   *pam_service_name;
 
 	int	permit_tun;
 
@@ -294,6 +295,7 @@ TAILQ_HEAD(include_list, include_item);
 		M_CP_STROPT(ca_sign_algorithms); \
 		M_CP_STROPT(routing_domain); \
 		M_CP_STROPT(permit_user_env_allowlist); \
+		M_CP_STROPT(pam_service_name); \
 		M_CP_STRARRAYOPT(authorized_keys_files, num_authkeys_files); \
 		M_CP_STRARRAYOPT(allow_users, num_allow_users); \
 		M_CP_STRARRAYOPT(deny_users, num_deny_users); \

sshd_config.5

@@ -1368,10 +1368,17 @@ and
 key exchange methods.
 The default is
 .Pa /etc/moduli .
+.It Cm PAMServiceName
+Specifies the service name used for Pluggable Authentication Modules (PAM)
+authentication, authorisation and session controls when
+.Cm UsePAM
+is enabled.
+The default is
+.Cm sshd .
 .It Cm PasswordAuthentication
 Specifies whether password authentication is allowed.
 The default is
-.Cm yes .
+.Cm sshd .
 .It Cm PermitEmptyPasswords
 When password authentication is allowed, it specifies whether the
 server allows login to accounts with empty password strings.