MFC r285261, r285279:

- Fix offset calculation in variable substitution
  in jail.conf.  The following did not work correctly:

 A="A_${B}_C_${D}"
 B="BBBBB"
 D="DDDD_${E}_FFFFF"
 E="EEEEE"

- Implement PF_IMMUTABLE flag and apply it to "name" and "jid" in
  jail.conf parameters.  This flag disallows redefinition of the parameter.

  "name" and/or "jid" are automatically defined in jail.conf by using
  the jail names at the front of jail parameter definitions.  However,
  one could override them by using a variable with the same name like
  $name = "foo".  This confused the parser and could end up with SIGSEGV.

  Note that this change also affects a case when all of parameters are
  defined in the command line arguments, not in jail.conf.  Specifically,
  "jail -c name=j1 name=j2" no longer works.  This should be harmless.

Approved by:	re (gjb)

2 files changed, 16 insertions, 10 deletions

diff --git a/usr.sbin/jail/config.c b/usr.sbin/jail/config.c
index 5820209..87b8ef9 100644
--- a/usr.sbin/jail/config.c
+++ b/usr.sbin/jail/config.c
@@ -111,8 +111,8 @@ static const struct ipspec intparams[] = {
 #ifdef INET6
     [KP_IP6_ADDR] =		{"ip6.addr",		0},
 #endif
-    [KP_JID] =			{"jid",			0},
-    [KP_NAME] =			{"name",		0},
+    [KP_JID] =			{"jid",			PF_IMMUTABLE},
+    [KP_NAME] =			{"name",		PF_IMMUTABLE},
     [KP_PATH] =			{"path",		0},
     [KP_PERSIST] =		{"persist",		0},
     [KP_SECURELEVEL] =		{"securelevel",		0},
@@ -130,9 +130,8 @@ load_config(void)
 	struct cfjail *j, *tj, *wj;
 	struct cfparam *p, *vp, *tp;
 	struct cfstring *s, *vs, *ns;
-	struct cfvar *v;
+	struct cfvar *v, *vv;
 	char *ep;
-	size_t varoff;
 	int did_self, jseq, pgen;
 
 	if (!strcmp(cfname, "-")) {
@@ -191,7 +190,6 @@ load_config(void)
 		    p->gen = ++pgen;
 		find_vars:
 		    TAILQ_FOREACH(s, &p->val, tq) {
-			varoff = 0;
 			while ((v = STAILQ_FIRST(&s->vars))) {
 				TAILQ_FOREACH(vp, &j->params, tq)
 					if (!strcmp(vp->name, v->name))
@@ -233,11 +231,13 @@ load_config(void)
 					goto bad_var;
 				}
 				s->s = erealloc(s->s, s->len + vs->len + 1);
-				memmove(s->s + v->pos + varoff + vs->len,
-				    s->s + v->pos + varoff,
-				    s->len - (v->pos + varoff) + 1);
-				memcpy(s->s + v->pos + varoff, vs->s, vs->len);
-				varoff += vs->len;
+				memmove(s->s + v->pos + vs->len,
+				    s->s + v->pos,
+				    s->len - v->pos + 1);
+				memcpy(s->s + v->pos, vs->s, vs->len);
+				vv = v;
+				while ((vv = STAILQ_NEXT(vv, tq)))
+					vv->pos += vs->len;
 				s->len += vs->len;
 				while ((vs = TAILQ_NEXT(vs, tq))) {
 					ns = emalloc(sizeof(struct cfstring));
@@ -362,6 +362,11 @@ add_param(struct cfjail *j, const struct cfparam *p, enum intparam ipnum,
 				break;
 	if (dp != NULL) {
 		/* Found it - append or replace. */
+		if (dp->flags & PF_IMMUTABLE) {
+			jail_warnx(j, "cannot redefine variable \"%s\".",
+			    dp->name);
+			return;
+		}
 		if (strcmp(dp->name, name)) {
 			free(dp->name);
 			dp->name = estrdup(name);
diff --git a/usr.sbin/jail/jailp.h b/usr.sbin/jail/jailp.h
index bfefca5..d2c929e 100644
--- a/usr.sbin/jail/jailp.h
+++ b/usr.sbin/jail/jailp.h
@@ -51,6 +51,7 @@
 #define PF_INT		0x20	/* Integer parameter */
 #define PF_CONV		0x40	/* Parameter duplicated in converted form */
 #define PF_REV		0x80	/* Run commands in reverse order on stopping */
+#define	PF_IMMUTABLE	0x100	/* Immutable parameter */
 
 #define JF_START	0x0001	/* -c */
 #define JF_SET		0x0002	/* -m */