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From:   Richard Guy Briggs <rgb@redhat.com>
To:     containers@lists.linux-foundation.org, linux-api@vger.kernel.org,
        Linux-Audit Mailing List <linux-audit@redhat.com>,
        linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        netdev@vger.kernel.org, netfilter-devel@vger.kernel.org
Cc:     Paul Moore <paul@paul-moore.com>, sgrubb@redhat.com,
        omosnace@redhat.com, dhowells@redhat.com, simo@redhat.com,
        eparis@parisplace.org, serge@hallyn.com, ebiederm@xmission.com,
        nhorman@tuxdriver.com, dwalsh@redhat.com, mpatel@redhat.com,
        Richard Guy Briggs <rgb@redhat.com>
Subject: [PATCH ghak90 V7 17/21] audit: add support for loginuid/sessionid set/get by netlink
Date:   Wed, 18 Sep 2019 21:22:34 -0400
Message-Id: <6cef16c2a019e61e49f4d62497b5ca8dab79b45f.1568834525.git.rgb@redhat.com>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Add the ability to get and set the login uid and to get the session id
using an audit netlink message using message types AUDIT_GET_LOGINUID
1024, AUDIT_SET_LOGINUID 1025 and AUDIT_GET_SESSIONID 1026 in addition
to using the proc filesystem.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
 include/uapi/linux/audit.h |  3 +++
 kernel/audit.c             | 62 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index e26729fc9943..eef42c8eea77 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -75,6 +75,9 @@
 #define AUDIT_SIGNAL_INFO2	1021	/* Get info auditd signal sender */
 #define AUDIT_GET_CONTID	1022	/* Get contid of a task */
 #define AUDIT_SET_CONTID	1023	/* Set contid of a task */
+#define AUDIT_GET_LOGINUID	1024	/* Get loginuid of a task */
+#define AUDIT_SET_LOGINUID	1025	/* Set loginuid of a task */
+#define AUDIT_GET_SESSIONID	1026	/* Set sessionid of a task */
 
 #define AUDIT_FIRST_USER_MSG	1100	/* Userspace messages mostly uninteresting to kernel */
 #define AUDIT_USER_AVC		1107	/* We filter this differently */
diff --git a/kernel/audit.c b/kernel/audit.c
index df92de20ed73..9e82de13d2eb 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1184,6 +1184,15 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 {
 	int err = 0;
 
+	/* These messages can work outside the initial namespaces */
+	switch (msg_type) {
+	case AUDIT_GET_LOGINUID:
+	case AUDIT_GET_SESSIONID:
+		return 0;
+		break;
+	default:  /* do more checks below */
+		break;
+	}
 	/* Only support initial user namespace for now. */
 	/*
 	 * We return ECONNREFUSED because it tricks userspace into thinking
@@ -1218,6 +1227,7 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type)
 	case AUDIT_MAKE_EQUIV:
 	case AUDIT_GET_CONTID:
 	case AUDIT_SET_CONTID:
+	case AUDIT_SET_LOGINUID:
 		/* Only support auditd and auditctl in initial pid namespace
 		 * for now. */
 		if (task_active_pid_ns(current) != &init_pid_ns)
@@ -1292,6 +1302,33 @@ static int audit_get_contid_status(struct sk_buff *skb)
 	return 0;
 }
 
+struct audit_loginuid_status { uid_t loginuid; };
+
+static int audit_get_loginuid_status(struct sk_buff *skb)
+{
+	u32 seq;
+	uid_t loginuid;
+	struct audit_loginuid_status ls;
+
+	loginuid = from_kuid(current_user_ns(), audit_get_loginuid(current));
+	ls.loginuid = loginuid;
+
+	seq = nlmsg_hdr(skb)->nlmsg_seq;
+	audit_send_reply(skb, seq, AUDIT_GET_LOGINUID, 0, 0, &ls, sizeof(ls));
+	return loginuid;
+}
+
+static int audit_get_sessionid_status(struct sk_buff *skb)
+{
+	u32 seq;
+	struct audit_sessionid_status { u32 sessionid; };
+	struct audit_sessionid_status ss = { audit_get_sessionid(current) };
+
+	seq = nlmsg_hdr(skb)->nlmsg_seq;
+	audit_send_reply(skb, seq, AUDIT_GET_SESSIONID, 0, 0, &ss, sizeof(ss));
+	return audit_get_sessionid(current);
+}
+
 static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature,
 				     u32 old_lock, u32 new_lock, int res)
 {
@@ -1740,6 +1777,31 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 		if (err)
 			return err;
 		break;
+	case AUDIT_SET_LOGINUID: {
+		uid_t *loginuid = data;
+		kuid_t kloginuid;
+
+		/* check if new data is valid */
+		if (nlmsg_len(nlh) < sizeof(u32))
+			return -EINVAL;
+
+		kloginuid = make_kuid(current_user_ns(), *loginuid);
+                if (!uid_valid(kloginuid))
+                        return -EINVAL;
+
+		return audit_set_loginuid(kloginuid);
+		break;
+	}
+	case AUDIT_GET_LOGINUID:
+		err = audit_get_loginuid_status(skb);
+		if (err)
+			return err;
+		break;
+	case AUDIT_GET_SESSIONID:
+		err = audit_get_sessionid_status(skb);
+		if (err)
+			return err;
+		break;
 	default:
 		err = -EINVAL;
 		break;
-- 
1.8.3.1