su: add --group and --supp-group options
These options allow to specify alternative groups. The command su(1) has to be executed by root. The implementation is based on Fedora runuser(1) command. For example: # su --group=kzak --supp-group=uuidd - # id uid=0(root) gid=1000(kzak) groups=0(root),985(uuidd),1000(kzak) non-root user: $ su --group=kzak - su: only root can specify alternative groups Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak
parent
4e1073c23b
commit
8528ea2f81
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@ -59,6 +59,12 @@ Pass
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to the shell which may or may not be useful depending on the
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shell.
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.TP
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\fB\-g\fR, \fB\-\-group\fR=\fIgroup\fR\fR
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specify the primary group, this option is allowed for root user only
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.TP
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\fB\-G\fR, \fB\-\-supp-group\fR=\fIgroup\fR\fR
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specify a supplemental group, this option is allowed for root user only
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.TP
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\fB\-\fR, \fB\-l\fR, \fB\-\-login\fR
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Starts the shell as login shell with an environment similar to a real
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login:
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@ -110,6 +110,8 @@ static struct option const longopts[] =
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{"login", no_argument, NULL, 'l'},
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{"preserve-environment", no_argument, NULL, 'p'},
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{"shell", required_argument, NULL, 's'},
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{"group", required_argument, NULL, 'g'},
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{"supp-group", required_argument, NULL, 'G'},
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{"help", no_argument, 0, 'h'},
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{"version", no_argument, 0, 'V'},
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{NULL, 0, NULL, 0}
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@ -548,11 +550,18 @@ modify_environment (const struct passwd *pw, const char *shell)
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/* Become the user and group(s) specified by PW. */
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static void
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init_groups (const struct passwd *pw)
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init_groups (const struct passwd *pw, gid_t *groups, int num_groups)
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{
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int retval;
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errno = 0;
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if (initgroups (pw->pw_name, pw->pw_gid) == -1)
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if (num_groups)
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retval = setgroups (num_groups, groups);
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else
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retval = initgroups (pw->pw_name, pw->pw_gid);
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if (retval == -1)
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{
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cleanup_pam (PAM_ABORT);
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err (EXIT_FAILURE, _("cannot set groups"));
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@ -659,6 +668,8 @@ usage (int status)
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-c, --command <command> pass a single command to the shell with -c\n\
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--session-command <command> pass a single command to the shell with -c\n\
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and do not create a new session\n\
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-g --group=group specify the primary group\n\
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-G --supp-group=group specify a supplemental group\n\
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-f, --fast pass -f to the shell (for csh or tcsh)\n\
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-m, --preserve-environment do not reset environment variables\n\
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-p same as -m\n\
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@ -680,6 +691,19 @@ void load_config(void)
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logindefs_load_file(_PATH_LOGINDEFS);
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}
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/*
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* Returns 1 if the current user is not root
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*/
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static int
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evaluate_uid(void)
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{
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uid_t ruid = getuid();
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uid_t euid = geteuid();
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/* if we're really root and aren't running setuid */
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return (uid_t) 0 == ruid && ruid == euid ? 0 : 1;
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}
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int
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main (int argc, char **argv)
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{
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@ -690,6 +714,11 @@ main (int argc, char **argv)
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char *shell = NULL;
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struct passwd *pw;
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struct passwd pw_copy;
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struct group *gr;
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gid_t groups[NGROUPS_MAX];
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int num_supp_groups = 0;
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int use_gid = 0;
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int restricted;
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setlocale (LC_ALL, "");
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bindtextdomain (PACKAGE, LOCALEDIR);
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@ -699,7 +728,7 @@ main (int argc, char **argv)
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simulate_login = false;
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change_environment = true;
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while ((optc = getopt_long (argc, argv, "c:flmps:hV", longopts, NULL)) != -1)
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while ((optc = getopt_long (argc, argv, "c:fg:G:lmps:hV", longopts, NULL)) != -1)
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{
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switch (optc)
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{
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@ -716,6 +745,26 @@ main (int argc, char **argv)
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fast_startup = true;
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break;
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case 'g':
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gr = getgrnam(optarg);
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if (!gr)
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errx(EXIT_FAILURE, _("group %s does not exist"), optarg);
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use_gid = 1;
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groups[0] = gr->gr_gid;
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break;
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case 'G':
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num_supp_groups++;
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if (num_supp_groups >= NGROUPS_MAX)
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errx(EXIT_FAILURE,
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_("can't specify more than %d supplemental groups"),
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NGROUPS_MAX - 1);
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gr = getgrnam(optarg);
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if (!gr)
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errx(EXIT_FAILURE, _("group %s does not exist"), optarg);
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groups[num_supp_groups] = gr->gr_gid;
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break;
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case 'l':
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simulate_login = true;
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break;
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@ -741,6 +790,8 @@ main (int argc, char **argv)
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}
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}
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restricted = evaluate_uid ();
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if (optind < argc && !strcmp (argv[optind], "-"))
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{
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simulate_login = true;
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@ -749,6 +800,9 @@ main (int argc, char **argv)
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if (optind < argc)
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new_user = argv[optind++];
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if ((num_supp_groups || use_gid) && restricted)
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errx(EXIT_FAILURE, _("only root can specify alternative groups"));
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logindefs_load_defaults = load_config;
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pw = getpwnam (new_user);
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@ -772,6 +826,17 @@ main (int argc, char **argv)
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: DEFAULT_SHELL);
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endpwent ();
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if (num_supp_groups && !use_gid)
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{
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pw->pw_gid = groups[1];
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memmove (groups, groups + 1, sizeof(gid_t) * num_supp_groups);
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}
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else if (use_gid)
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{
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pw->pw_gid = groups[0];
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num_supp_groups++;
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}
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authenticate (pw);
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if (request_same_session || !command || !pw->pw_uid)
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@ -790,7 +855,7 @@ main (int argc, char **argv)
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}
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shell = xstrdup (shell ? shell : pw->pw_shell);
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init_groups (pw);
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init_groups (pw, groups, num_supp_groups);
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create_watching_parent ();
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/* Now we're in the child. */
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