In preparation for raising NGROUPS and NGROUPS_MAX, change base

system callers of getgroups(), getgrouplist(), and setgroups() to
allocate buffers dynamically.  Specifically, allocate a buffer of size
sysconf(_SC_NGROUPS_MAX)+1 (+2 in a few cases to allow for overflow).

This (or similar gymnastics) is required for the code to actually follow
the POSIX.1-2008 specification where {NGROUPS_MAX} may differ at runtime
and where getgroups may return {NGROUPS_MAX}+1 results on systems like
FreeBSD which include the primary group.

In id(1), don't pointlessly add the primary group to the list of all
groups, it is always the first result from getgroups().  In principle
the old code was more portable, but this was only done in one of the two
places where getgroups() was called to the overall effect was pointless.

Document the actual POSIX requirements in the getgroups(2) and
setgroups(2) manpages.  We do not yet support a dynamic NGROUPS, but we
may in the future.

MFC after:	2 weeks

lib/libc/gen/initgroups.3

@@ -65,6 +65,13 @@ function may fail and set
 .Va errno
 for any of the errors specified for the library function
 .Xr setgroups 2 .
+It may also return:
+.Bl -tag -width Er
+.It Bq Er ENOMEM
+The
+.Fn initgroups
+function was unable to allocate temporary storage.
+.El
 .Sh SEE ALSO
 .Xr setgroups 2 ,
 .Xr getgrouplist 3

lib/libc/gen/initgroups.c

@@ -35,10 +35,12 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 
-#include <stdio.h>
 #include "namespace.h"
 #include <err.h>
 #include "un-namespace.h"
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 
 int
@@ -46,14 +48,21 @@ initgroups(uname, agroup)
 	const char *uname;
 	gid_t agroup;
 {
-	int ngroups;
+	int ngroups, ret;
+	long ngroups_max;
+	gid_t *groups;
+
 	/*
-	 * Provide space for one group more than NGROUPS to allow
+	 * Provide space for one group more than possible to allow
 	 * setgroups to fail and set errno.
 	 */
-	gid_t groups[NGROUPS + 1];
+	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 2;
+	if ((groups = malloc(sizeof(*groups) * ngroups_max)) == NULL)
+		return (ENOMEM);
 
-	ngroups = NGROUPS + 1;
+	ngroups = (int)ngroups_max;
 	getgrouplist(uname, agroup, groups, &ngroups);
-	return (setgroups(ngroups, groups));
+	ret = setgroups(ngroups, groups);
+	free(groups);
+	return (ret);
 }

lib/libc/rpc/auth_unix.c

@@ -185,23 +185,29 @@ authunix_create(machname, uid, gid, len, aup_gids)
 AUTH *
 authunix_create_default()
 {
-	int len;
+	int ngids;
+	long ngids_max;
 	char machname[MAXHOSTNAMELEN + 1];
 	uid_t uid;
 	gid_t gid;
-	gid_t gids[NGROUPS_MAX];
+	gid_t *gids;
+
+	ngids_max = sysconf(_SC_NGROUPS_MAX) + 1;
+	gids = malloc(sizeof(gid_t) * ngids_max);
+	if (gids == NULL)
+		return (NULL);
 
 	if (gethostname(machname, sizeof machname) == -1)
 		abort();
 	machname[sizeof(machname) - 1] = 0;
 	uid = geteuid();
 	gid = getegid();
-	if ((len = getgroups(NGROUPS_MAX, gids)) < 0)
+	if ((ngids = getgroups(ngids_max, gids)) < 0)
 		abort();
-	if (len > NGRPS)
+	if (ngids > NGRPS)
-		len = NGRPS;
+		ngids = NGRPS;
 	/* XXX: interface problem; those should all have been unsigned */
-	return (authunix_create(machname, (int)uid, (int)gid, len,
+	return (authunix_create(machname, (int)uid, (int)gid, ngids,
 	    (int *)gids));
 }
 

lib/libc/sys/getgroups.2

@@ -58,10 +58,7 @@ The
 system call
 returns the actual number of groups returned in
 .Fa gidset .
-No more than
+At least one and as many as {NGROUPS_MAX}+1 values may be returned.
-.Dv NGROUPS_MAX
-will ever
-be returned.
 If
 .Fa gidsetlen
 is zero,
@@ -92,6 +89,11 @@ an invalid address.
 .Sh SEE ALSO
 .Xr setgroups 2 ,
 .Xr initgroups 3
+.Sh STANDARDS
+The
+.Fn getgroups
+system call conforms to
+.St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn getgroups

lib/libc/sys/setgroups.2

@@ -53,9 +53,7 @@ The
 argument
 indicates the number of entries in the array and must be no
 more than
-.Dv NGROUPS ,
+.Dv {NGROUPS_MAX}+1 .
-as defined in
-.In sys/param.h .
 .Pp
 Only the super-user may set a new group list.
 .Sh RETURN VALUES
@@ -71,7 +69,7 @@ The caller is not the super-user.
 The number specified in the
 .Fa ngroups
 argument is larger than the
-.Dv NGROUPS
+.Dv {NGROUPS_MAX}+1
 limit.
 .It Bq Er EFAULT
 The address specified for

usr.bin/id/id.c

@@ -258,7 +258,8 @@ id_print(struct passwd *pw, int use_ggl, int p_euid, int p_egid)
 	gid_t gid, egid, lastgid;
 	uid_t uid, euid;
 	int cnt, ngroups;
-	gid_t groups[NGROUPS + 1];
+	long ngroups_max;
+	gid_t *groups;
 	const char *fmt;
 
 	if (pw != NULL) {
@@ -270,12 +271,16 @@ id_print(struct passwd *pw, int use_ggl, int p_euid, int p_egid)
 		gid = getgid();
 	}
 
+	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
+	if ((groups = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
+		err(1, "malloc");
+
 	if (use_ggl && pw != NULL) {
-		ngroups = NGROUPS + 1;
+		ngroups = ngroups_max;
 		getgrouplist(pw->pw_name, gid, groups, &ngroups);
 	}
 	else {
-		ngroups = getgroups(NGROUPS + 1, groups);
+		ngroups = getgroups(ngroups_max, groups);
 	}
 
 	if (pw != NULL)
@@ -306,6 +311,7 @@ id_print(struct passwd *pw, int use_ggl, int p_euid, int p_egid)
 		lastgid = gid;
 	}
 	printf("\n");
+	free(groups);
 }
 
 #ifdef USE_BSM_AUDIT
@@ -361,15 +367,19 @@ group(struct passwd *pw, int nflag)
 {
 	struct group *gr;
 	int cnt, id, lastid, ngroups;
-	gid_t groups[NGROUPS + 1];
+	long ngroups_max;
+	gid_t *groups;
 	const char *fmt;
 
+	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
+	if ((groups = malloc(sizeof(gid_t) * (ngroups_max))) == NULL)
+		err(1, "malloc");
+
 	if (pw) {
-		ngroups = NGROUPS + 1;
+		ngroups = ngroups_max;
 		(void) getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);
 	} else {
-		groups[0] = getgid();
+		ngroups = getgroups(ngroups_max, groups);
-		ngroups = getgroups(NGROUPS, groups + 1) + 1;
 	}
 	fmt = nflag ? "%s" : "%u";
 	for (lastid = -1, cnt = 0; cnt < ngroups; ++cnt) {
@@ -389,6 +399,7 @@ group(struct passwd *pw, int nflag)
 		lastid = id;
 	}
 	(void)printf("\n");
+	free(groups);
 }
 
 void

usr.bin/newgrp/newgrp.c

@@ -146,8 +146,8 @@ restoregrps(void)
 static void
 addgroup(const char *grpname)
 {
-	gid_t grps[NGROUPS_MAX];
+	gid_t *grps;
-	long lgid;
+	long lgid, ngrps_max;
 	int dbmember, i, ngrps;
 	gid_t egid;
 	struct group *grp;
@@ -185,7 +185,10 @@ addgroup(const char *grpname)
 		}
 	}
 
-	if ((ngrps = getgroups(NGROUPS_MAX, (gid_t *)grps)) < 0) {
+	ngrps_max = sysconf(_SC_NGROUPS_MAX) + 1;
+	if ((grps = malloc(sizeof(gid_t) * ngrps_max)) == NULL)
+		err(1, "malloc");
+	if ((ngrps = getgroups(ngrps_max, (gid_t *)grps)) < 0) {
 		warn("getgroups");
 		return;
 	}
@@ -217,7 +220,7 @@ addgroup(const char *grpname)
 
 	/* Add old effective gid to supp. list if it does not exist. */
 	if (egid != grp->gr_gid && !inarray(egid, grps, ngrps)) {
-		if (ngrps == NGROUPS_MAX)
+		if (ngrps == ngrps_max)
 			warnx("too many groups");
 		else {
 			grps[ngrps++] = egid;
@@ -231,6 +234,7 @@ addgroup(const char *grpname)
 		}
 	}
 
+	free(grps);
 }
 
 static int

usr.bin/quota/quota.c

@@ -117,7 +117,8 @@ int
 main(int argc, char *argv[])
 {
 	int ngroups; 
-	gid_t mygid, gidset[NGROUPS];
+	long ngroups_max;
+	gid_t mygid, *gidset;
 	int i, ch, gflag = 0, uflag = 0, errflag = 0;
 
 	while ((ch = getopt(argc, argv, "f:ghlrquv")) != -1) {
@@ -159,13 +160,18 @@ main(int argc, char *argv[])
 			errflag += showuid(getuid());
 		if (gflag) {
 			mygid = getgid();
-			ngroups = getgroups(NGROUPS, gidset);
+			ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
+			if ((gidset = malloc(sizeof(gid_t) * ngroups_max))
+			    == NULL)
+				err(1, "malloc");
+			ngroups = getgroups(ngroups_max, gidset);
 			if (ngroups < 0)
 				err(1, "getgroups");
 			errflag += showgid(mygid);
 			for (i = 0; i < ngroups; i++)
 				if (gidset[i] != mygid)
 					errflag += showgid(gidset[i]);
+			free(gidset);
 		}
 		return(errflag);
 	}

usr.sbin/chown/chown.c

@@ -269,7 +269,8 @@ chownerr(const char *file)
 {
 	static uid_t euid = -1;
 	static int ngroups = -1;
-	gid_t groups[NGROUPS_MAX];
+	static long ngroups_max;
+	gid_t *groups;
 
 	/* Check for chown without being root. */
 	if (errno != EPERM || (uid != (uid_t)-1 &&
@@ -281,7 +282,10 @@ chownerr(const char *file)
 	/* Check group membership; kernel just returns EPERM. */
 	if (gid != (gid_t)-1 && ngroups == -1 &&
 	    euid == (uid_t)-1 && (euid = geteuid()) != 0) {
-		ngroups = getgroups(NGROUPS_MAX, groups);
+		ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
+		if ((groups = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
+			err(1, "malloc");
+		ngroups = getgroups(ngroups_max, groups);
 		while (--ngroups >= 0 && gid != groups[ngroups]);
 		if (ngroups < 0) {
 			warnx("you are not a member of group %s", gname);

usr.sbin/chroot/chroot.c

@@ -69,9 +69,10 @@ main(argc, argv)
 	struct passwd	*pw;
 	char		*endp, *p;
 	const char	*shell;
-	gid_t		gid, gidlist[NGROUPS_MAX];
+	gid_t		gid, *gidlist;
 	uid_t		uid;
 	int		ch, gids;
+	long		ngroups_max;
 
 	gid = 0;
 	uid = 0;
@@ -117,8 +118,11 @@ main(argc, argv)
 		}
 	}
 
+	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
+	if ((gidlist = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
+		err(1, "malloc");
 	for (gids = 0;
-	    (p = strsep(&grouplist, ",")) != NULL && gids < NGROUPS_MAX; ) {
+	    (p = strsep(&grouplist, ",")) != NULL && gids < ngroups_max; ) {
 		if (*p == '\0')
 			continue;
 
@@ -135,7 +139,7 @@ main(argc, argv)
 		}
 		gids++;
 	}
-	if (p != NULL && gids == NGROUPS_MAX)
+	if (p != NULL && gids == ngroups_max)
 		errx(1, "too many supplementary groups provided");
 
 	if (user != NULL) {

usr.sbin/jail/jail.c

@@ -104,7 +104,7 @@ extern char **environ;
 	lcap = login_getpwclass(pwd);					\
 	if (lcap == NULL)						\
 		err(1, "getpwclass: %s", username);			\
-	ngroups = NGROUPS;						\
+	ngroups = ngroups_max;						\
 	if (getgrouplist(username, pwd->pw_gid, groups, &ngroups) != 0)	\
 		err(1, "getgrouplist: %s", username);			\
 } while (0)
@@ -115,10 +115,11 @@ main(int argc, char **argv)
 	login_cap_t *lcap = NULL;
 	struct iovec rparams[2];
 	struct passwd *pwd = NULL;
-	gid_t groups[NGROUPS];
+	gid_t *groups;
 	size_t sysvallen;
 	int ch, cmdarg, i, jail_set_flags, jid, ngroups, sysval;
 	int hflag, iflag, Jflag, lflag, rflag, uflag, Uflag;
+	long ngroups_max;
 	unsigned pi;
 	char *ep, *jailname, *securelevel, *username, *JidFile;
 	char errmsg[ERRMSG_SIZE], enforce_statfs[4];
@@ -132,6 +133,10 @@ main(int argc, char **argv)
 	jailname = securelevel = username = JidFile = cleanenv = NULL;
 	fp = NULL;
 
+	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;	
+	if ((groups = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
+		err(1, "malloc");
+
 	while ((ch = getopt(argc, argv, "cdhilmn:r:s:u:U:J:")) != -1) {
 		switch (ch) {
 		case 'd':

usr.sbin/jexec/jexec.c

@@ -59,7 +59,7 @@ static void	usage(void);
 	lcap = login_getpwclass(pwd);					\
 	if (lcap == NULL)						\
 		err(1, "getpwclass: %s", username);			\
-	ngroups = NGROUPS;						\
+	ngroups = ngroups_max;						\
 	if (getgrouplist(username, pwd->pw_gid, groups, &ngroups) != 0)	\
 		err(1, "getgrouplist: %s", username);			\
 } while (0)
@@ -71,12 +71,17 @@ main(int argc, char *argv[])
 	int jid;
 	login_cap_t *lcap = NULL;
 	struct passwd *pwd = NULL;
-	gid_t groups[NGROUPS];
+	gid_t *groups = NULL;
 	int ch, ngroups, uflag, Uflag;
+	long ngroups_max;
 	char *ep, *username;
 	ch = uflag = Uflag = 0;
 	username = NULL;
 
+	ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
+	if ((groups = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
+		err(1, "malloc");
+
 	while ((ch = getopt(argc, argv, "nu:U:")) != -1) {
 		switch (ch) {
 		case 'n':

usr.sbin/lpr/lpc/lpc.c

@@ -356,7 +356,8 @@ ingroup(const char *grname)
 {
 	static struct group *gptr=NULL;
 	static int ngroups = 0;
-	static gid_t groups[NGROUPS];
+	static long ngroups_max;
+	static gid_t *groups;
 	register gid_t gid;
 	register int i;
 
@@ -365,7 +366,10 @@ ingroup(const char *grname)
 			warnx("warning: unknown group '%s'", grname);
 			return(0);
 		}
-		ngroups = getgroups(NGROUPS, groups);
+		ngroups_max = sysconf(_SC_NGROUPS_MAX);
+		if ((groups = malloc(sizeof(gid_t) * ngroups_max)) == NULL)
+			err(1, "malloc");
+		ngroups = getgroups(ngroups_max, groups);
 		if (ngroups < 0)
 			err(1, "getgroups");
 	}