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From b2a41801904c4b281a717dde7f5e146cbd4500b3 Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Mon, 15 Feb 2016 13:55:37 +0100
Subject: [PATCH 66/84] su: clean up groups initialization
This patch does not change any su/runuser behaviour, code changes:
* don't use huge groups[NGROUPS_MAX]; the array has 256k, but we need
it only occasionally when -G/-g specified.
* the current code uses groups[0] for -g and the rest for -G, this patch adds
'gid' to remember -g argument to avoid memmove()
* add function add_supp_group() to simplify su_main()
* add note about -G and -g relation to the man pages (undocumented now)
Upstream: http://github.com/karelzak/util-linux/commit/c619d3d167115990e9228b27851e0cc2faa8f936
Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=1304426
Signed-off-by: Karel Zak <kzak@redhat.com>
---
login-utils/runuser.1 | 5 ++--
login-utils/su-common.c | 68 +++++++++++++++++++++++++++----------------------
login-utils/su.1 | 5 ++--
3 files changed, 44 insertions(+), 34 deletions(-)
diff --git a/login-utils/runuser.1 b/login-utils/runuser.1
index 7201ff0..d82dbb0 100644
--- a/login-utils/runuser.1
+++ b/login-utils/runuser.1
@@ -75,8 +75,9 @@ shell.
\fB\-g\fR, \fB\-\-group\fR=\fIgroup\fR\fR
specify the primary group, this option is allowed for root user only
.TP
-\fB\-G\fR, \fB\-\-supp-group\fR=\fIgroup\fR\fR
-specify a supplemental group, this option is allowed for root user only
+.BR \-G , " \-\-supp\-group" = \fIgroup
+Specify a supplemental group. This option is available to the root user only. The first specified
+supplementary group is also used as a primary group if the option \fB\-\-group\fR is unspecified.
.TP
\fB\-\fR, \fB\-l\fR, \fB\-\-login\fR
Starts the shell as login shell with an environment similar to a real
diff --git a/login-utils/su-common.c b/login-utils/su-common.c
index dd87804..d53d690 100644
--- a/login-utils/su-common.c
+++ b/login-utils/su-common.c
@@ -535,7 +535,7 @@ modify_environment (const struct passwd *pw, const char *shell)
/* Become the user and group(s) specified by PW. */
static void
-init_groups (const struct passwd *pw, gid_t *groups, int num_groups)
+init_groups (const struct passwd *pw, gid_t *groups, size_t num_groups)
{
int retval;
@@ -707,6 +707,28 @@ evaluate_uid(void)
return (uid_t) 0 == ruid && ruid == euid ? 0 : 1;
}
+static gid_t
+add_supp_group(const char *name, gid_t **groups, size_t *ngroups)
+{
+ struct group *gr;
+
+ if (*ngroups >= NGROUPS_MAX)
+ errx(EXIT_FAILURE,
+ P_("specifying more than %d supplemental group is not possible",
+ "specifying more than %d supplemental groups is not possible",
+ NGROUPS_MAX - 1), NGROUPS_MAX - 1);
+
+ gr = getgrnam(name);
+ if (!gr)
+ errx(EXIT_FAILURE, _("group %s does not exist"), name);
+
+ *groups = xrealloc(*groups, sizeof(gid_t) * (*ngroups + 1));
+ (*groups)[*ngroups] = gr->gr_gid;
+ (*ngroups)++;
+
+ return gr->gr_gid;
+}
+
int
su_main (int argc, char **argv, int mode)
{
@@ -717,10 +739,12 @@ su_main (int argc, char **argv, int mode)
char *shell = NULL;
struct passwd *pw;
struct passwd pw_copy;
- struct group *gr;
- gid_t groups[NGROUPS_MAX];
- int num_supp_groups = 0;
- int use_gid = 0;
+
+ gid_t *groups = NULL;
+ size_t ngroups = 0;
+ bool use_supp = false;
+ bool use_gid = false;
+ gid_t gid = 0;
static const struct option longopts[] = {
{"command", required_argument, NULL, 'c'},
@@ -765,23 +789,13 @@ su_main (int argc, char **argv, int mode)
break;
case 'g':
- gr = getgrnam(optarg);
- if (!gr)
- errx(EXIT_FAILURE, _("group %s does not exist"), optarg);
- use_gid = 1;
- groups[0] = gr->gr_gid;
+ use_gid = true;
+ gid = add_supp_group(optarg, &groups, &ngroups);
break;
case 'G':
- num_supp_groups++;
- if (num_supp_groups >= NGROUPS_MAX)
- errx(EXIT_FAILURE,
- _("can't specify more than %d supplemental groups"),
- NGROUPS_MAX - 1);
- gr = getgrnam(optarg);
- if (!gr)
- errx(EXIT_FAILURE, _("group %s does not exist"), optarg);
- groups[num_supp_groups] = gr->gr_gid;
+ use_supp = true;
+ add_supp_group(optarg, &groups, &ngroups);
break;
case 'l':
@@ -852,7 +866,7 @@ su_main (int argc, char **argv, int mode)
break;
}
- if ((num_supp_groups || use_gid) && restricted)
+ if ((use_supp || use_gid) && restricted)
errx(EXIT_FAILURE, _("only root can specify alternative groups"));
logindefs_load_defaults = load_config;
@@ -878,16 +892,10 @@ su_main (int argc, char **argv, int mode)
: DEFAULT_SHELL);
endpwent ();
- if (num_supp_groups && !use_gid)
- {
- pw->pw_gid = groups[1];
- memmove (groups, groups + 1, sizeof(gid_t) * num_supp_groups);
- }
- else if (use_gid)
- {
+ if (use_supp && !use_gid)
pw->pw_gid = groups[0];
- num_supp_groups++;
- }
+ else if (use_gid)
+ pw->pw_gid = gid;
authenticate (pw);
@@ -912,7 +920,7 @@ su_main (int argc, char **argv, int mode)
shell = xstrdup (shell ? shell : pw->pw_shell);
}
- init_groups (pw, groups, num_supp_groups);
+ init_groups (pw, groups, ngroups);
if (!simulate_login || command)
suppress_pam_info = 1; /* don't print PAM info messages */
diff --git a/login-utils/su.1 b/login-utils/su.1
index eab1a6f..1f69868 100644
--- a/login-utils/su.1
+++ b/login-utils/su.1
@@ -62,8 +62,9 @@ shell.
\fB\-g\fR, \fB\-\-group\fR=\fIgroup\fR\fR
specify the primary group, this option is allowed for root user only
.TP
-\fB\-G\fR, \fB\-\-supp-group\fR=\fIgroup\fR\fR
-specify a supplemental group, this option is allowed for root user only
+.BR \-G , " \-\-supp\-group" = \fIgroup
+Specify a supplemental group. This option is available to the root user only. The first specified
+supplementary group is also used as a primary group if the option \fB\-\-group\fR is unspecified.
.TP
\fB\-\fR, \fB\-l\fR, \fB\-\-login\fR
Starts the shell as login shell with an environment similar to a real
--
2.7.4