env(1): grow -L user/class and -U user/class options

This allows one to set the environment of the specified user either from
login.conf alone (-L) or both login.conf and ~/.login_conf if present (-U).

This is a supporting feature to allow service(8) to pull in the environment
of the "daemon" class before invoking the rc script.

This is a part of D21481.

Submitted by:	Andrew Gierth < andrew_tao173.riddles.org.uk>

usr.bin/env/Makefile

@@ -4,4 +4,6 @@
 PROG=	env
 SRCS=	env.c envopts.c
 
+LIBADD=	util
+
 .include <bsd.prog.mk>

usr.bin/env/env.1

@@ -31,7 +31,7 @@
 .\" From FreeBSD: src/usr.bin/printenv/printenv.1,v 1.17 2002/11/26 17:33:35 ru Exp
 .\" $FreeBSD$
 .\"
-.Dd November 7, 2019
+.Dd January 19, 2020
 .Dt ENV 1
 .Os
 .Sh NAME
@@ -40,6 +40,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl 0iv
+.Op Fl L Ns | Ns Fl U Ar user Ns Op / Ns Ar class
 .Op Fl P Ar altpath
 .Op Fl S Ar string
 .Op Fl u Ar name
@@ -76,6 +77,28 @@ The environment inherited
 by
 .Nm
 is ignored completely.
+.\"	-L | -U
+.It Fl L | Fl U Ar user Ns Op / Ns Ar class
+Add the environment variable definitions from
+.Xr login.conf 5
+for the specified user and login class to the environment, after
+processing any
+.Fl i
+or
+.Fl u
+options, but before processing any
+.Ar name Ns = Ns Ar value
+options.
+If
+.Fl L
+is used, only the system-wide
+.Pa /etc/login.conf.db
+file is read; if
+.Fl U
+is used, then the specified user's
+.Pa ~/.login_conf
+is read as well.
+The user may be specified by name or by uid.
 .\"	-P
 .It Fl P Ar altpath
 Search the set of directories as specified by
@@ -450,6 +473,7 @@ option as a synonym for
 .Xr printenv 1 ,
 .Xr sh 1 ,
 .Xr execvp 3 ,
+.Xr login.conf 5 ,
 .Xr environ 7
 .Sh STANDARDS
 The
@@ -457,7 +481,7 @@ The
 utility conforms to
 .St -p1003.1-2001 .
 The
-.Fl P , S , u
+.Fl 0 , L , P , S , U , u
 and
 .Fl v
 options are non-standard extensions supported by
@@ -474,6 +498,12 @@ and
 .Fl v
 options were added in
 .Fx 6.0 .
+The
+.Fl 0 , L
+and
+.Fl U
+options were added in
+.Fx 13.0 .
 .Sh BUGS
 The
 .Nm

usr.bin/env/env.c

@@ -44,11 +44,16 @@ static char sccsid[] = "@(#)env.c	8.3 (Berkeley) 4/2/94";
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
+#include <sys/types.h>
+
 #include <err.h>
 #include <errno.h>
+#include <login_cap.h>
+#include <pwd.h>
+#include <stdbool.h>
 #include <stdio.h>
-#include <string.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 #include "envopts.h"
@@ -71,13 +76,23 @@ main(int argc, char **argv)
 {
 	char *altpath, **ep, *p, **parg, term;
 	char *cleanenv[1];
+	char *login_class, *login_name;
+	struct passwd *pw;
+	login_cap_t *lc;
+	bool login_as_user;
+	uid_t uid;
 	int ch, want_clear;
 	int rtrn;
 
 	altpath = NULL;
+	login_class = NULL;
+	login_name = NULL;
+	pw = NULL;
+	lc = NULL;
+	login_as_user = false;
 	want_clear = 0;
 	term = '\n';
-	while ((ch = getopt(argc, argv, "-0iP:S:u:v")) != -1)
+	while ((ch = getopt(argc, argv, "-0iL:P:S:U:u:v")) != -1)
 		switch(ch) {
 		case '-':
 		case 'i':
@@ -86,6 +101,12 @@ main(int argc, char **argv)
 		case '0':
 			term = '\0';
 			break;
+		case 'U':
+			login_as_user = true;
+			/* FALLTHROUGH */
+		case 'L':
+			login_name = optarg;
+			break;
 		case 'P':
 			altpath = strdup(optarg);
 			break;
@@ -119,6 +140,48 @@ main(int argc, char **argv)
 		if (env_verbosity)
 			fprintf(stderr, "#env clearing environ\n");
 	}
+	if (login_name != NULL) {
+		login_class = strchr(login_name, '/');
+		if (login_class)
+			*login_class++ = '\0';
+		pw = getpwnam(login_name);
+		if (pw == NULL) {
+			char *endp = NULL;
+			errno = 0;
+			uid = strtoul(login_name, &endp, 10);
+			if (errno == 0 && *endp == '\0')
+				pw = getpwuid(uid);
+		}
+		if (pw == NULL)
+			errx(EXIT_FAILURE, "no such user: %s", login_name);
+		if (login_class != NULL) {
+			lc = login_getclass(login_class);
+			if (lc == NULL)
+				errx(EXIT_FAILURE, "no such login class: %s",
+				    login_class);
+		} else {
+			lc = login_getpwclass(pw);
+			if (lc == NULL)
+				errx(EXIT_FAILURE, "login_getpwclass failed");
+		}
+
+		/*
+		 * This is not done with setusercontext() because that will
+		 * try and use ~/.login_conf even when we don't want it to.
+		 */
+		setclassenvironment(lc, pw, 1);
+		setclassenvironment(lc, pw, 0);
+		if (login_as_user) {
+			login_close(lc);
+			if ((lc = login_getuserclass(pw)) != NULL) {
+				setclassenvironment(lc, pw, 1);
+				setclassenvironment(lc, pw, 0);
+			}
+		}
+		endpwent();
+		if (lc != NULL)
+			login_close(lc);
+	}
 	for (argv += optind; *argv && (p = strchr(*argv, '=')); ++argv) {
 		if (env_verbosity)
 			fprintf(stderr, "#env setenv:\t%s\n", *argv);
@@ -154,7 +217,7 @@ static void
 usage(void)
 {
 	(void)fprintf(stderr,
-	    "usage: env [-0iv] [-P utilpath] [-S string] [-u name]\n"
+	    "usage: env [-0iv] [-L|-U user[/class]] [-P utilpath] [-S string] [-u name]\n"
 	    "           [name=value ...] [utility [argument ...]]\n");
 	exit(1);
 }