git: afb6f8307494 - stable/13 - mountd: Fix handling of usernames that start with a digit

The branch stable/13 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=afb6f83074944e3843bb171656af9f52ac9d4d98

commit afb6f83074944e3843bb171656af9f52ac9d4d98
Author:     Rick Macklem <rmacklem@FreeBSD.org>
AuthorDate: 2021-11-18 21:35:25 +0000
Commit:     Rick Macklem <rmacklem@FreeBSD.org>
CommitDate: 2021-12-02 01:08:35 +0000

    mountd: Fix handling of usernames that start with a digit
    
    yocalebo_gmail.com submitted a patch for mountd.c that
    fixes the case where a username starts with a digit.
    Without this patch, the username that starts with a
    digit is misinterpreted as a numeric uid.
    With this patch, any string that does not entirely
    convert to a decimal number via strtoul() is considered
    a user/group name.
    
    (cherry picked from commit f4bf849bb894f4934b8df6c04a820dfa52e9576c)
---
 usr.sbin/mountd/mountd.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/usr.sbin/mountd/mountd.c b/usr.sbin/mountd/mountd.c
index c66ac13b3016..0c077b857d7e 100644
--- a/usr.sbin/mountd/mountd.c
+++ b/usr.sbin/mountd/mountd.c
@@ -3534,6 +3534,8 @@ parsecred(char *namelist, struct expcred *cr)
 	struct group *gr;
 	gid_t groups[NGROUPS_MAX + 1];
 	int ngroups;
+	unsigned long name_ul;
+	char *end = NULL;
 
 	/*
 	 * Set up the unprivileged user.
@@ -3548,10 +3550,11 @@ parsecred(char *namelist, struct expcred *cr)
 	names = namelist;
 	name = strsep_quote(&names, ":");
 	/* Bug?  name could be NULL here */
-	if (isdigit(*name) || *name == '-')
-		pw = getpwuid(atoi(name));
-	else
+	name_ul = strtoul(name, &end, 10);
+	if (*end != '\0' || end == name)
 		pw = getpwnam(name);
+	else
+		pw = getpwuid((uid_t)name_ul);
 	/*
 	 * Credentials specified as those of a user.
 	 */
@@ -3573,8 +3576,9 @@ parsecred(char *namelist, struct expcred *cr)
 		if (ngroups > 1 && groups[0] == groups[1]) {
 			ngroups--;
 			inpos = 2;
-		} else
+		} else {
 			inpos = 1;
+		}
 		if (ngroups > NGROUPS_MAX)
 			ngroups = NGROUPS_MAX;
 		if (ngroups > SMALLNGROUPS)
@@ -3589,25 +3593,26 @@ parsecred(char *namelist, struct expcred *cr)
 	 * Explicit credential specified as a colon separated list:
 	 *	uid:gid:gid:...
 	 */
-	if (pw != NULL)
+	if (pw != NULL) {
 		cr->cr_uid = pw->pw_uid;
-	else if (isdigit(*name) || *name == '-')
-		cr->cr_uid = atoi(name);
-	else {
+	} else if (*end != '\0' || end == name) {
 		syslog(LOG_ERR, "unknown user: %s", name);
 		return;
+	} else {
+		cr->cr_uid = name_ul;
 	}
 	cr->cr_ngroups = 0;
 	while (names != NULL && *names != '\0' && cr->cr_ngroups < NGROUPS_MAX) {
 		name = strsep_quote(&names, ":");
-		if (isdigit(*name) || *name == '-') {
-			groups[cr->cr_ngroups++] = atoi(name);
-		} else {
+		name_ul = strtoul(name, &end, 10);
+		if (*end != '\0' || end == name) {
 			if ((gr = getgrnam(name)) == NULL) {
 				syslog(LOG_ERR, "unknown group: %s", name);
 				continue;
 			}
 			groups[cr->cr_ngroups++] = gr->gr_gid;
+		} else {
+			groups[cr->cr_ngroups++] = name_ul;
 		}
 	}
 	if (names != NULL && *names != '\0' && cr->cr_ngroups == NGROUPS_MAX)