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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: john.johansen@canonical.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-audit@redhat.com,
	netfilter-devel@vger.kernel.org, sds@tycho.nsa.gov
Subject: [PATCH v25 07/25] LSM: Use lsmblob in security_secctx_to_secid
Date: Tue,  9 Mar 2021 06:42:25 -0800	[thread overview]
Message-ID: <20210309144243.12519-8-casey@schaufler-ca.com> (raw)
In-Reply-To: <20210309144243.12519-1-casey@schaufler-ca.com>

Change the security_secctx_to_secid interface to use a lsmblob
structure in place of the single u32 secid in support of
module stacking. Change its callers to do the same.

The security module hook is unchanged, still passing back a secid.
The infrastructure passes the correct entry from the lsmblob.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: netdev@vger.kernel.org
Cc: netfilter-devel@vger.kernel.org
To: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/linux/security.h          | 26 ++++++++++++++++++--
 kernel/cred.c                     |  4 +---
 net/netfilter/nft_meta.c          | 10 ++++----
 net/netfilter/xt_SECMARK.c        |  7 +++++-
 net/netlabel/netlabel_unlabeled.c | 23 +++++++++++-------
 security/security.c               | 40 ++++++++++++++++++++++++++-----
 6 files changed, 85 insertions(+), 25 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index b63a14866464..1a1fbe0746a0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -196,6 +196,27 @@ static inline bool lsmblob_equal(struct lsmblob *bloba, struct lsmblob *blobb)
 extern int lsm_name_to_slot(char *name);
 extern const char *lsm_slot_to_name(int slot);
 
+/**
+ * lsmblob_value - find the first non-zero value in an lsmblob structure.
+ * @blob: Pointer to the data
+ *
+ * This needs to be used with extreme caution, as the cases where
+ * it is appropriate are rare.
+ *
+ * Return the first secid value set in the lsmblob.
+ * There should only be one.
+ */
+static inline u32 lsmblob_value(const struct lsmblob *blob)
+{
+	int i;
+
+	for (i = 0; i < LSMBLOB_ENTRIES; i++)
+		if (blob->secid[i])
+			return blob->secid[i];
+
+	return 0;
+}
+
 /* These functions are in security/commoncap.c */
 extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
 		       int cap, unsigned int opts);
@@ -524,7 +545,8 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
 int security_netlink_send(struct sock *sk, struct sk_buff *skb);
 int security_ismaclabel(const char *name);
 int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
-int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
+int security_secctx_to_secid(const char *secdata, u32 seclen,
+			     struct lsmblob *blob);
 void security_release_secctx(char *secdata, u32 seclen);
 void security_inode_invalidate_secctx(struct inode *inode);
 int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
@@ -1364,7 +1386,7 @@ static inline int security_secid_to_secctx(u32 secid, char **secdata, u32 *secle
 
 static inline int security_secctx_to_secid(const char *secdata,
 					   u32 seclen,
-					   u32 *secid)
+					   struct lsmblob *blob)
 {
 	return -EOPNOTSUPP;
 }
diff --git a/kernel/cred.c b/kernel/cred.c
index 22e0e7cbefde..848306c7d823 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -757,14 +757,12 @@ EXPORT_SYMBOL(set_security_override);
 int set_security_override_from_ctx(struct cred *new, const char *secctx)
 {
 	struct lsmblob blob;
-	u32 secid;
 	int ret;
 
-	ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
+	ret = security_secctx_to_secid(secctx, strlen(secctx), &blob);
 	if (ret < 0)
 		return ret;
 
-	lsmblob_init(&blob, secid);
 	return set_security_override(new, &blob);
 }
 EXPORT_SYMBOL(set_security_override_from_ctx);
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index a7e01e9952f1..f9448e81798e 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -809,21 +809,21 @@ static const struct nla_policy nft_secmark_policy[NFTA_SECMARK_MAX + 1] = {
 
 static int nft_secmark_compute_secid(struct nft_secmark *priv)
 {
-	u32 tmp_secid = 0;
+	struct lsmblob blob;
 	int err;
 
-	err = security_secctx_to_secid(priv->ctx, strlen(priv->ctx), &tmp_secid);
+	err = security_secctx_to_secid(priv->ctx, strlen(priv->ctx), &blob);
 	if (err)
 		return err;
 
-	if (!tmp_secid)
+	if (!lsmblob_is_set(&blob))
 		return -ENOENT;
 
-	err = security_secmark_relabel_packet(tmp_secid);
+	err = security_secmark_relabel_packet(lsmblob_value(&blob));
 	if (err)
 		return err;
 
-	priv->secid = tmp_secid;
+	priv->secid = lsmblob_value(&blob);
 	return 0;
 }
 
diff --git a/net/netfilter/xt_SECMARK.c b/net/netfilter/xt_SECMARK.c
index 75625d13e976..9845d98e6b77 100644
--- a/net/netfilter/xt_SECMARK.c
+++ b/net/netfilter/xt_SECMARK.c
@@ -43,13 +43,14 @@ secmark_tg(struct sk_buff *skb, const struct xt_action_param *par)
 
 static int checkentry_lsm(struct xt_secmark_target_info *info)
 {
+	struct lsmblob blob;
 	int err;
 
 	info->secctx[SECMARK_SECCTX_MAX - 1] = '\0';
 	info->secid = 0;
 
 	err = security_secctx_to_secid(info->secctx, strlen(info->secctx),
-				       &info->secid);
+				       &blob);
 	if (err) {
 		if (err == -EINVAL)
 			pr_info_ratelimited("invalid security context \'%s\'\n",
@@ -57,6 +58,10 @@ static int checkentry_lsm(struct xt_secmark_target_info *info)
 		return err;
 	}
 
+	/* xt_secmark_target_info can't be changed to use lsmblobs because
+	 * it is exposed as an API. Use lsmblob_value() to get the one
+	 * value that got set by security_secctx_to_secid(). */
+	info->secid = lsmblob_value(&blob);
 	if (!info->secid) {
 		pr_info_ratelimited("unable to map security context \'%s\'\n",
 				    info->secctx);
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index ccb491642811..df9448af23dd 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -882,7 +882,7 @@ static int netlbl_unlabel_staticadd(struct sk_buff *skb,
 	void *addr;
 	void *mask;
 	u32 addr_len;
-	u32 secid;
+	struct lsmblob blob;
 	struct netlbl_audit audit_info;
 
 	/* Don't allow users to add both IPv4 and IPv6 addresses for a
@@ -906,13 +906,18 @@ static int netlbl_unlabel_staticadd(struct sk_buff *skb,
 	ret_val = security_secctx_to_secid(
 		                  nla_data(info->attrs[NLBL_UNLABEL_A_SECCTX]),
 				  nla_len(info->attrs[NLBL_UNLABEL_A_SECCTX]),
-				  &secid);
+				  &blob);
 	if (ret_val != 0)
 		return ret_val;
 
+	/* netlbl_unlhsh_add will be changed to pass a struct lsmblob *
+	 * instead of a u32 later in this patch set. security_secctx_to_secid()
+	 * will only be setting one entry in the lsmblob struct, so it is
+	 * safe to use lsmblob_value() to get that one value. */
+
 	return netlbl_unlhsh_add(&init_net,
-				 dev_name, addr, mask, addr_len, secid,
-				 &audit_info);
+				 dev_name, addr, mask, addr_len,
+				 lsmblob_value(&blob), &audit_info);
 }
 
 /**
@@ -933,7 +938,7 @@ static int netlbl_unlabel_staticadddef(struct sk_buff *skb,
 	void *addr;
 	void *mask;
 	u32 addr_len;
-	u32 secid;
+	struct lsmblob blob;
 	struct netlbl_audit audit_info;
 
 	/* Don't allow users to add both IPv4 and IPv6 addresses for a
@@ -955,13 +960,15 @@ static int netlbl_unlabel_staticadddef(struct sk_buff *skb,
 	ret_val = security_secctx_to_secid(
 		                  nla_data(info->attrs[NLBL_UNLABEL_A_SECCTX]),
 				  nla_len(info->attrs[NLBL_UNLABEL_A_SECCTX]),
-				  &secid);
+				  &blob);
 	if (ret_val != 0)
 		return ret_val;
 
+	/* security_secctx_to_secid() will only put one secid into the lsmblob
+	 * so it's safe to use lsmblob_value() to get the secid. */
 	return netlbl_unlhsh_add(&init_net,
-				 NULL, addr, mask, addr_len, secid,
-				 &audit_info);
+				 NULL, addr, mask, addr_len,
+				 lsmblob_value(&blob), &audit_info);
 }
 
 /**
diff --git a/security/security.c b/security/security.c
index aa81f2d629af..4fcffbf1ff8d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2140,10 +2140,22 @@ int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
 }
 EXPORT_SYMBOL(security_secid_to_secctx);
 
-int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
+int security_secctx_to_secid(const char *secdata, u32 seclen,
+			     struct lsmblob *blob)
 {
-	*secid = 0;
-	return call_int_hook(secctx_to_secid, 0, secdata, seclen, secid);
+	struct security_hook_list *hp;
+	int rc;
+
+	lsmblob_init(blob, 0);
+	hlist_for_each_entry(hp, &security_hook_heads.secctx_to_secid, list) {
+		if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
+			continue;
+		rc = hp->hook.secctx_to_secid(secdata, seclen,
+					      &blob->secid[hp->lsmid->slot]);
+		if (rc != 0)
+			return rc;
+	}
+	return 0;
 }
 EXPORT_SYMBOL(security_secctx_to_secid);
 
@@ -2294,10 +2306,26 @@ 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,
+				     u32 *secid)
 {
-	return call_int_hook(socket_getpeersec_dgram, -ENOPROTOOPT, sock,
-			     skb, secid);
+	struct security_hook_list *hp;
+	int rc = -ENOPROTOOPT;
+
+	/*
+	 * Only one security module should provide a real hook for
+	 * this. A stub or bypass like is used in BPF should either
+	 * (somehow) leave rc unaltered or return -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, secid);
+		if (rc != -ENOPROTOOPT)
+			break;
+	}
+	return rc;
 }
 EXPORT_SYMBOL(security_socket_getpeersec_dgram);
 
-- 
2.29.2

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  parent reply	other threads:[~2021-03-09 14:50 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210309144243.12519-1-casey.ref@schaufler-ca.com>
2021-03-09 14:42 ` [PATCH v25 00/25] LSM: Module stacking for AppArmor Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 01/25] LSM: Infrastructure management of the sock security Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 02/25] LSM: Add the lsmblob data structure Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 03/25] LSM: provide lsm name and id slot mappings Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 04/25] IMA: avoid label collisions with stacked LSMs Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 05/25] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 06/25] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2021-03-09 14:42   ` Casey Schaufler [this message]
2021-03-09 14:42   ` [PATCH v25 08/25] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 09/25] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 10/25] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 11/25] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 12/25] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2021-03-09 19:46     ` kernel test robot
2021-03-09 19:46     ` [RFC PATCH] LSM: audit_sig_lsm can be static kernel test robot
2021-03-09 14:42   ` [PATCH v25 13/25] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 14/25] LSM: Specify which LSM to display Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 15/25] LSM: Ensure the correct LSM context releaser Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 16/25] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 17/25] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2021-03-12 16:16     ` Chuck Lever III
2021-03-09 14:42   ` [PATCH v25 18/25] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 19/25] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 20/25] LSM: Verify LSM display sanity in binder Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 21/25] audit: add support for non-syscall auxiliary records Casey Schaufler
2021-03-09 17:55     ` kernel test robot
2021-03-09 14:42   ` [PATCH v25 22/25] Audit: Add new record for multiple process LSM attributes Casey Schaufler
2021-03-09 17:04     ` kernel test robot
2021-03-09 17:19     ` kernel test robot
2021-03-09 14:42   ` [PATCH v25 23/25] Audit: Add a new record for multiple object " Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 24/25] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2021-03-09 14:42   ` [PATCH v25 25/25] AppArmor: Remove the exclusive flag Casey Schaufler

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