passwd + /etc/shadow: chage "change time" field too

function                                             old     new   delta
update_passwd                                       1171    1270     +99

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 31 insertions, 4 deletions

diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
index aa1e2ed08..3aab40175 100644
--- a/libbb/update_passwd.c
+++ b/libbb/update_passwd.c
@@ -87,6 +87,12 @@ int FAST_FUNC update_passwd(const char *filename,
 	int i;
 	int changed_lines;
 	int ret = -1; /* failure */
+	/* used as a bool: "are we modifying /etc/shadow?" */
+#if ENABLE_FEATURE_SHADOWPASSWDS
+	const char *shadow = strstr(filename, "shadow");
+#else
+# define shadow NULL
+#endif
 
 	filename = xmalloc_follow_symlinks(filename);
 	if (filename == NULL)
@@ -100,7 +106,7 @@ int FAST_FUNC update_passwd(const char *filename,
 	name = xasprintf("%s:", name);
 	user_len = strlen(name);
 
-	if (ENABLE_FEATURE_SHADOWPASSWDS && strstr(filename, "shadow"))
+	if (shadow)
 		old_fp = fopen(filename, "r+");
 	else
 		old_fp = fopen_or_warn(filename, "r+");
@@ -215,8 +221,18 @@ int FAST_FUNC update_passwd(const char *filename,
 		) {
 			/* Change passwd */
 			cp = strchrnul(cp, ':'); /* move past old passwd */
-			/* name: + new_passwd + :rest of line */
-			fprintf(new_fp, "%s%s%s\n", name, new_passwd, cp);
+
+			if (shadow && *cp == ':') {
+				/* /etc/shadow's field 3 (passwd change date) needs updating */
+				/* move past old change date */
+				cp = strchrnul(cp + 1, ':');
+				/* "name:" + "new_passwd" + ":" + "change date" + ":rest of line" */
+				fprintf(new_fp, "%s%s:%u%s\n", name, new_passwd,
+					(unsigned)(time(NULL)) / (24*60*60), cp);
+			} else {
+				/* "name:" + "new_passwd" + ":rest of line" */
+				fprintf(new_fp, "%s%s%s\n", name, new_passwd, cp);
+			}
 			changed_lines++;
 		} /* else delete user or group: skip the line */
  next:
diff --git a/loginutils/adduser.c b/loginutils/adduser.c
index 00232375b..136dcdff8 100644
--- a/loginutils/adduser.c
+++ b/loginutils/adduser.c
@@ -169,7 +169,18 @@ int adduser_main(int argc UNUSED_PARAM, char **argv)
 		free(p);
 
 #if ENABLE_FEATURE_SHADOWPASSWDS
-	p = xasprintf("!:%u:0:99999:7:::", (unsigned)(time(NULL) / 86400)); /* sp->sp_lstchg */
+	/* /etc/shadow fields:
+	 * 1. username
+	 * 2. encrypted password
+	 * 3. last password change (unix date (unix time/24*60*60))
+	 * 4. minimum days required between password changes
+	 * 5. maximum days password is valid
+	 * 6. days before password is to expire that user is warned
+	 * 7. days after password expires that account is disabled
+	 * 8. unix date when login expires (may no longer be used)
+	 */
+	/* fields:     2 3  4 5     6 78 */
+	p = xasprintf("!:%u:0:99999:7:::", (unsigned)(time(NULL)) / (24*60*60));
 	/* ignore errors: if file is missing we suppose admin doesn't want it */
 	update_passwd(bb_path_shadow_file, pw.pw_name, p, NULL);
 	if (ENABLE_FEATURE_CLEAN_UP)