chsh: Add libuser support

This is based directly on lchsh which is a part of libuser. libuser.{c,h}
exist because exactly the same code is needed for both chsh and chfn.

[kzak@redhat.com: cleanup err() usage]

Signed-off-by: Cody Maloney <cmaloney@theoreticalchaos.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/login-utils/libuser.c b/login-utils/libuser.c
new file mode 100644
index 000000000..53c7ac9e2
--- /dev/null
+++ b/login-utils/libuser.c
@@ -0,0 +1,71 @@
+/*
+ *   libuser.c -- Utilize libuser to set a user attribute
+ *   (c) 2012 by Cody Maloney <cmaloney@theoreticalchaos.com>
+ *
+ *   this program is free software.  you can redistribute it and
+ *   modify it under the terms of the gnu general public license.
+ *   there is no warranty.
+ *
+ */
+
+#include "libuser.h"
+
+#include <grp.h>
+#include <libuser/user.h>
+#include <unistd.h>
+
+#include "auth.h"
+#include "c.h"
+#include "nls.h"
+
+static int auth_lu(const char *service_name, struct lu_context *ctx, uid_t uid,
+			const char *username);
+
+static int auth_lu(const char *service_name, struct lu_context *ctx, uid_t uid,
+			const char *username) {
+	if(!lu_uses_elevated_privileges(ctx)) {
+		/* Drop privileges */
+		if (setegid(getgid()) == -1)
+			err(EXIT_FAILURE, _("Couldn't drop group privileges"));
+		if (seteuid(getuid()) == -1)
+			err(EXIT_FAILURE, _("Couldn't drop group privileges"));
+		return TRUE;
+	}
+
+	return auth_pam(service_name, uid, username);
+}
+
+int set_value_libuser(const char *service_name, const char *username, uid_t uid,
+			const char *attr, const char *val) {
+	struct lu_context *ctx;
+	struct lu_error *error = NULL;
+	struct lu_ent *ent;
+
+	ctx = lu_start(username, lu_user, NULL, NULL, lu_prompt_console_quiet,
+			NULL, &error);
+	if (ctx == NULL)
+		errx(EXIT_FAILURE, _("libuser initialization failed: %s."),
+			lu_strerror(error));
+
+	if(!auth_lu(service_name, ctx, uid, username)) {
+		errno = EACCES;
+		err(EXIT_FAILURE, _("changing user attribute failed"));
+	}
+
+	/* Look up the user's record. */
+	ent = lu_ent_new();
+	if (lu_user_lookup_name(ctx, username, ent, &error) == FALSE) {
+		lu_end(ctx);
+		errx(EXIT_FAILURE, _("user \"%s\" does not exist."), username);
+	}
+
+	lu_ent_set_string(ent, attr, val);
+	if (!lu_user_modify(ctx, ent, &error)) {
+		lu_ent_free(ent);
+		lu_end(ctx);
+		errx(EXIT_FAILURE, _("user attribute not changed: %s"), lu_strerror(error));
+	}
+	lu_ent_free(ent);
+	lu_end(ctx);
+	return TRUE;
+}