cron(8): Add MAILFROM ability for crontabs

This changes the sender mail address in a similar fashion to how MAILTO may
change the recipient. The default from address remains unchanged.

MFC after:	1 week

3 files changed, 16 insertions, 5 deletions

diff --git a/usr.sbin/cron/cron/cron.8 b/usr.sbin/cron/cron/cron.8
index 5dc9595e0061..c436cc2d3962 100644
--- a/usr.sbin/cron/cron/cron.8
+++ b/usr.sbin/cron/cron/cron.8
@@ -17,7 +17,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 19, 2017
+.Dd April 15, 2019
 .Dt CRON 8
 .Os
 .Sh NAME
@@ -79,6 +79,9 @@ commands, any output is mailed to the owner of the crontab (or to the user
 named in the
 .Ev MAILTO
 environment variable in the crontab, if such exists).
+The from address of this mail may be set with the
+.Ev MAILFROM
+environment variable.
 .Pp
 Additionally,
 .Nm
diff --git a/usr.sbin/cron/cron/do_command.c b/usr.sbin/cron/cron/do_command.c
index f62303a5df29..13d14e442a27 100644
--- a/usr.sbin/cron/cron/do_command.c
+++ b/usr.sbin/cron/cron/do_command.c
@@ -93,7 +93,7 @@ child_process(e, u)
 {
 	int		stdin_pipe[2], stdout_pipe[2];
 	register char	*input_data;
-	char		*usernm, *mailto;
+	char		*usernm, *mailto, *mailfrom;
 	int		children = 0;
 # if defined(LOGIN_CAP)
 	struct passwd	*pwd;
@@ -111,6 +111,7 @@ child_process(e, u)
 	 */
 	usernm = env_get("LOGNAME", e->envp);
 	mailto = env_get("MAILTO", e->envp);
+	mailfrom = env_get("MAILFROM", e->envp);
 
 #ifdef PAM
 	/* use PAM to see if the user's account is available,
@@ -503,8 +504,12 @@ child_process(e, u)
 					warn("%s", MAILCMD);
 					(void) _exit(ERROR_EXIT);
 				}
-				fprintf(mail, "From: Cron Daemon <%s@%s>\n",
-					usernm, hostname);
+				if (mailfrom == NULL || *mailfrom == '\0')
+					fprintf(mail, "From: Cron Daemon <%s@%s>\n",
+					    usernm, hostname);
+				else
+					fprintf(mail, "From: Cron Daemon <%s>\n",
+					    mailfrom);
 				fprintf(mail, "To: %s\n", mailto);
 				fprintf(mail, "Subject: Cron <%s@%s> %s\n",
 					usernm, first_word(hostname, "."),
diff --git a/usr.sbin/cron/crontab/crontab.5 b/usr.sbin/cron/crontab/crontab.5
index 697242b4d0fc..fa2895a10195 100644
--- a/usr.sbin/cron/crontab/crontab.5
+++ b/usr.sbin/cron/crontab/crontab.5
@@ -17,7 +17,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd June 6, 2018
+.Dd April 15, 2019
 .Dt CRONTAB 5
 .Os
 .Sh NAME
@@ -116,6 +116,9 @@ If
 .Ev MAILTO
 is defined (and non-empty), mail is
 sent to the user so named.
+If
+.Ev MAILFROM
+is defined (and non-empty), its value will be used as the from address.
 .Ev MAILTO
 may also be used to direct mail to multiple recipients
 by separating recipient users with a comma.