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)