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From: Casey Schaufler <casey@schaufler-ca.com>
To: casey.schaufler@intel.com, jmorris@namei.org,
	linux-security-module@vger.kernel.org, selinux@vger.kernel.org
Cc: casey@schaufler-ca.com, keescook@chromium.org,
	john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp,
	paul@paul-moore.com, sds@tycho.nsa.gov, netdev@vger.kernel.org
Subject: [PATCH v18 05/23] net: Prepare UDS for security module stacking
Date: Wed,  8 Jul 2020 17:12:16 -0700	[thread overview]
Message-ID: <20200709001234.9719-6-casey@schaufler-ca.com> (raw)
In-Reply-To: <20200709001234.9719-1-casey@schaufler-ca.com>

Change the data used in UDS SO_PEERSEC processing from a
secid to a more general struct lsmblob. Update the
security_socket_getpeersec_dgram() interface to use the
lsmblob. There is a small amount of scaffolding code
that will come out when the security_secid_to_secctx()
code is brought in line with the lsmblob.

The secid field of the unix_skb_parms structure has been
replaced with a pointer to an lsmblob structure, and the
lsmblob is allocated as needed. This is similar to how the
list of passed files is managed. While an lsmblob structure
will fit in the available space today, there is no guarantee
that the addition of other data to the unix_skb_parms or
support for additional security modules wouldn't exceed what
is available.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: netdev@vger.kernel.org
---
 include/linux/security.h |  7 +++++--
 include/net/af_unix.h    |  2 +-
 include/net/scm.h        |  8 +++++---
 net/ipv4/ip_sockglue.c   |  8 +++++---
 net/unix/af_unix.c       | 12 +++++++++---
 net/unix/scm.c           |  6 ++++++
 security/security.c      | 18 +++++++++++++++---
 7 files changed, 46 insertions(+), 15 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 6d403a522918..d81e8886d799 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1397,7 +1397,8 @@ int security_socket_shutdown(struct socket *sock, int how);
 int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb);
 int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
 				      int __user *optlen, unsigned len);
-int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid);
+int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
+				     struct lsmblob *blob);
 int security_sk_alloc(struct sock *sk, int family, gfp_t priority);
 void security_sk_free(struct sock *sk);
 void security_sk_clone(const struct sock *sk, struct sock *newsk);
@@ -1535,7 +1536,9 @@ static inline int security_socket_getpeersec_stream(struct socket *sock, char __
 	return -ENOPROTOOPT;
 }
 
-static inline int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)
+static inline int security_socket_getpeersec_dgram(struct socket *sock,
+						   struct sk_buff *skb,
+						   struct lsmblob *blob)
 {
 	return -ENOPROTOOPT;
 }
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index f42fdddecd41..e99c84677e14 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -36,7 +36,7 @@ struct unix_skb_parms {
 	kgid_t			gid;
 	struct scm_fp_list	*fp;		/* Passed files		*/
 #ifdef CONFIG_SECURITY_NETWORK
-	u32			secid;		/* Security ID		*/
+	struct lsmblob		*lsmdata;	/* Security LSM data	*/
 #endif
 	u32			consumed;
 } __randomize_layout;
diff --git a/include/net/scm.h b/include/net/scm.h
index 1ce365f4c256..e2e71c4bf9d0 100644
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -33,7 +33,7 @@ struct scm_cookie {
 	struct scm_fp_list	*fp;		/* Passed files		*/
 	struct scm_creds	creds;		/* Skb credentials	*/
 #ifdef CONFIG_SECURITY_NETWORK
-	u32			secid;		/* Passed security ID 	*/
+	struct lsmblob		lsmblob;	/* Passed LSM data	*/
 #endif
 };
 
@@ -46,7 +46,7 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl);
 #ifdef CONFIG_SECURITY_NETWORK
 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
 {
-	security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
+	security_socket_getpeersec_dgram(sock, NULL, &scm->lsmblob);
 }
 #else
 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
@@ -97,7 +97,9 @@ static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct sc
 	int err;
 
 	if (test_bit(SOCK_PASSSEC, &sock->flags)) {
-		err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
+		/* Scaffolding - it has to be element 0 for now */
+		err = security_secid_to_secctx(scm->lsmblob.secid[0],
+					       &secdata, &seclen);
 
 		if (!err) {
 			put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 84ec3703c909..3ea1103b4c29 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -130,15 +130,17 @@ static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
 
 static void ip_cmsg_recv_security(struct msghdr *msg, struct sk_buff *skb)
 {
+	struct lsmblob lb;
 	char *secdata;
-	u32 seclen, secid;
+	u32 seclen;
 	int err;
 
-	err = security_socket_getpeersec_dgram(NULL, skb, &secid);
+	err = security_socket_getpeersec_dgram(NULL, skb, &lb);
 	if (err)
 		return;
 
-	err = security_secid_to_secctx(secid, &secdata, &seclen);
+	/* Scaffolding - it has to be element 0 */
+	err = security_secid_to_secctx(lb.secid[0], &secdata, &seclen);
 	if (err)
 		return;
 
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 3385a7a0b231..d246aefcf4da 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -138,17 +138,23 @@ static struct hlist_head *unix_sockets_unbound(void *addr)
 #ifdef CONFIG_SECURITY_NETWORK
 static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
 {
-	UNIXCB(skb).secid = scm->secid;
+	UNIXCB(skb).lsmdata = kmemdup(&scm->lsmblob, sizeof(scm->lsmblob),
+				      GFP_KERNEL);
 }
 
 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
 {
-	scm->secid = UNIXCB(skb).secid;
+	if (likely(UNIXCB(skb).lsmdata))
+		scm->lsmblob = *(UNIXCB(skb).lsmdata);
+	else
+		lsmblob_init(&scm->lsmblob, 0);
 }
 
 static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
 {
-	return (scm->secid == UNIXCB(skb).secid);
+	if (likely(UNIXCB(skb).lsmdata))
+		return lsmblob_equal(&scm->lsmblob, UNIXCB(skb).lsmdata);
+	return false;
 }
 #else
 static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
diff --git a/net/unix/scm.c b/net/unix/scm.c
index 8c40f2b32392..3094323935a4 100644
--- a/net/unix/scm.c
+++ b/net/unix/scm.c
@@ -142,6 +142,12 @@ void unix_destruct_scm(struct sk_buff *skb)
 	scm.pid  = UNIXCB(skb).pid;
 	if (UNIXCB(skb).fp)
 		unix_detach_fds(&scm, skb);
+#ifdef CONFIG_SECURITY_NETWORK
+	if (UNIXCB(skb).lsmdata) {
+		kfree(UNIXCB(skb).lsmdata);
+		UNIXCB(skb).lsmdata = NULL;
+	}
+#endif
 
 	/* Alas, it calls VFS */
 	/* So fscking what? fput() had been SMP-safe since the last Summer */
diff --git a/security/security.c b/security/security.c
index f54c6dfd9b89..2122ed9df058 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2204,10 +2204,22 @@ int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
 				optval, optlen, len);
 }
 
-int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid)
+int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
+				     struct lsmblob *blob)
 {
-	return call_int_hook(socket_getpeersec_dgram, -ENOPROTOOPT, sock,
-			     skb, secid);
+	struct security_hook_list *hp;
+	int rc = -ENOPROTOOPT;
+
+	hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_dgram,
+			     list) {
+		if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+			continue;
+		rc = hp->hook.socket_getpeersec_dgram(sock, skb,
+						&blob->secid[hp->lsmid->slot]);
+		if (rc != 0)
+			break;
+	}
+	return rc;
 }
 EXPORT_SYMBOL(security_socket_getpeersec_dgram);
 
-- 
2.24.1


  parent reply	other threads:[~2020-07-09  0:23 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200709001234.9719-1-casey.ref@schaufler-ca.com>
2020-07-09  0:12 ` [PATCH v18 00/23] LSM: Module stacking for AppArmor Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 01/23] LSM: Infrastructure management of the sock security Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 02/23] LSM: Create and manage the lsmblob data structure Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 03/23] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 04/23] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2020-07-09  0:12   ` Casey Schaufler [this message]
2020-07-09 16:11     ` [PATCH v18 05/23] net: Prepare UDS for security module stacking Stephen Smalley
2020-07-09 16:28       ` John Johansen
2020-07-09 19:24         ` Casey Schaufler
2020-07-09 19:54         ` Stephen Smalley
2020-07-09  0:12   ` [PATCH v18 06/23] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 07/23] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 08/23] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 09/23] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 10/23] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 11/23] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 12/23] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 13/23] LSM: Specify which LSM to display Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 14/23] LSM: Ensure the correct LSM context releaser Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 15/23] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 16/23] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 17/23] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 18/23] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 19/23] LSM: Verify LSM display sanity in binder Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 20/23] Audit: Add new record for multiple process LSM attributes Casey Schaufler
2020-07-09  0:12     ` Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 21/23] Audit: Add a new record for multiple object " Casey Schaufler
2020-07-09  0:12     ` Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 22/23] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2020-07-09  1:30     ` Jann Horn
2020-07-24  1:08       ` Casey Schaufler
2020-07-09  0:12   ` [PATCH v18 23/23] AppArmor: Remove the exclusive flag Casey Schaufler

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