On Wednesday 24 October 2007 12:53:40 Ralf Friedl wrote:
> Hi
>
> I have a patch for adduser to support the option "-S: Create a system
> user", which is presently accepted but ignored.
>
> Also I changed the range for normal users to start at 1000 instead of
> 500, which is what most current distributions do.
>
> As a side note:
> It is not possible to create users with group 0. The code seems to
> create a new group with same and same number as the new user.
> Why would that be useful?
Hi,
Seems to be standard behaviour...
By default, each user in Debian GNU/Linux is given a corresponding
group with the same name. Usergroups allow group writable directories
to be easily maintained by placing the appropriate users in the new
group, setting the set-group-ID bit in the directory, and ensuring that
all users use a umask of 002. If this option is turned off by setting
USERGROUPS to no, all users’ GIDs are set to USERS_GID
> Also, I think it is possible that this implementation results in
> duplicate user ids:
> The first loop, "while (!fgetpwent_r(..." find a free user id.
> The second loop, "while (getgrgid(p->pw_uid)) p->pw_uid++;" increments
> uid until it finds an unused group id.
> It is possible that this incremented uid is in use as a user id.
>
> Regards
> Ralf Friedl
>
maybe this could fix the problem you report:
/* remix */
/* EDR recoded such that the uid may be passed in *p */
static int passwd_study(const char *filename, struct passwd *p)
{
enum { min = 500, max = 65000 };
FILE *passwd;
passwd = xfopen(filename, "r");
/* if uid is out of bounds, set to min */
if ((p->pw_uid > max) || (p->pw_uid < min))
p->pw_uid = min;
/* check for an already in use login name */
if (getpwnam(p->pw_name))
return 1;
/* check for a free uid */
while (getpwuid(p->pw_uid))
p->pw_uid++;
if (!p->pw_gid) {
/* create new gid always = uid and re-check if the uid is free
*/
while (getgrgid(p->pw_uid) && getpwuid(p->pw_uid))
p->pw_uid++;
p->pw_gid = p->pw_uid;
/* check for an already in use group name */
if (getgrnam(p->pw_name) != NULL)
return 3;
}
/* bounds check, could not be less than min */
if (p->pw_uid > max)
return 2;
return 0;
}
This is only a proof of concept and is only compile tested.
If it works for you, your patch could be easily integrated.
Ciao,
Tito
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