lsm: infrastructure management of the key security blob

Move management of the key->security blob out of the individual security
modules and into the security infrastructure. Instead of allocating the
blobs from within the modules the modules tell the infrastructure how
much space is required, and the space is allocated there.  There are
no existing modules that require a key_free hook, so the call to it and
the definition for it have been removed.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 855db460e08bc6c38631e94eec4fbf99abf8a42d..8cc60644f3bd0882fe881421e83826fe4843e95d 100644 (file)
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -403,7 +403,6 @@ LSM_HOOK(int, 0, xfrm_decode_session, struct sk_buff *skb, u32 *secid,
 #ifdef CONFIG_KEYS
 LSM_HOOK(int, 0, key_alloc, struct key *key, const struct cred *cred,
         unsigned long flags)
-LSM_HOOK(void, LSM_RET_VOID, key_free, struct key *key)
 LSM_HOOK(int, 0, key_permission, key_ref_t key_ref, const struct cred *cred,
         enum key_need_perm need_perm)
 LSM_HOOK(int, 0, key_getsecurity, struct key *key, char **buffer)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index efd4a0655159cca65f687c0d3fd26227e9b622b3..7233bc0737be677555afd3a009f9f9c9464e203a 100644 (file)
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -76,6 +76,7 @@ struct lsm_blob_sizes {
        int     lbs_sock;
        int     lbs_superblock;
        int     lbs_ipc;
+       int     lbs_key;
        int     lbs_msg_msg;
        int     lbs_task;
        int     lbs_xattr_count; /* number of xattr slots in new_xattrs array */

diff --git a/security/security.c b/security/security.c
index 9c3fb2f60e2a6f2c0f1c0ec5be394086997d0c1c..dfb7fea6080c3464c1ea864bfaa3bab2182332a1 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -227,6 +227,7 @@ static void __init lsm_set_blob_sizes(struct lsm_blob_sizes *needed)
                blob_sizes.lbs_inode = sizeof(struct rcu_head);
        lsm_set_blob_size(&needed->lbs_inode, &blob_sizes.lbs_inode);
        lsm_set_blob_size(&needed->lbs_ipc, &blob_sizes.lbs_ipc);
+       lsm_set_blob_size(&needed->lbs_key, &blob_sizes.lbs_key);
        lsm_set_blob_size(&needed->lbs_msg_msg, &blob_sizes.lbs_msg_msg);
        lsm_set_blob_size(&needed->lbs_sock, &blob_sizes.lbs_sock);
        lsm_set_blob_size(&needed->lbs_superblock, &blob_sizes.lbs_superblock);
@@ -402,6 +403,9 @@ static void __init ordered_lsm_init(void)
        init_debug("file blob size       = %d\n", blob_sizes.lbs_file);
        init_debug("inode blob size      = %d\n", blob_sizes.lbs_inode);
        init_debug("ipc blob size        = %d\n", blob_sizes.lbs_ipc);
+#ifdef CONFIG_KEYS
+       init_debug("key blob size        = %d\n", blob_sizes.lbs_key);
+#endif /* CONFIG_KEYS */
        init_debug("msg_msg blob size    = %d\n", blob_sizes.lbs_msg_msg);
        init_debug("sock blob size       = %d\n", blob_sizes.lbs_sock);
        init_debug("superblock blob size = %d\n", blob_sizes.lbs_superblock);
@@ -718,6 +722,29 @@ static int lsm_ipc_alloc(struct kern_ipc_perm *kip)
        return 0;
 }
 
+#ifdef CONFIG_KEYS
+/**
+ * lsm_key_alloc - allocate a composite key blob
+ * @key: the key that needs a blob
+ *
+ * Allocate the key blob for all the modules
+ *
+ * Returns 0, or -ENOMEM if memory can't be allocated.
+ */
+static int lsm_key_alloc(struct key *key)
+{
+       if (blob_sizes.lbs_key == 0) {
+               key->security = NULL;
+               return 0;
+       }
+
+       key->security = kzalloc(blob_sizes.lbs_key, GFP_KERNEL);
+       if (key->security == NULL)
+               return -ENOMEM;
+       return 0;
+}
+#endif /* CONFIG_KEYS */
+
 /**
  * lsm_msg_msg_alloc - allocate a composite msg_msg blob
  * @mp: the msg_msg that needs a blob
@@ -5316,7 +5343,14 @@ EXPORT_SYMBOL(security_skb_classify_flow);
 int security_key_alloc(struct key *key, const struct cred *cred,
                       unsigned long flags)
 {
-       return call_int_hook(key_alloc, key, cred, flags);
+       int rc = lsm_key_alloc(key);
+
+       if (unlikely(rc))
+               return rc;
+       rc = call_int_hook(key_alloc, key, cred, flags);
+       if (unlikely(rc))
+               security_key_free(key);
+       return rc;
 }
 
 /**
@@ -5327,7 +5361,8 @@ int security_key_alloc(struct key *key, const struct cred *cred,
  */
 void security_key_free(struct key *key)
 {
-       call_void_hook(key_free, key);
+       kfree(key->security);
+       key->security = NULL;
 }
 
 /**

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e08ffb1ddd5a3ed8a61d019c02ea35d8738c7757..7dbf169f733fddf07e35d189c43ccee90f08511c 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6663,11 +6663,7 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred,
                             unsigned long flags)
 {
        const struct task_security_struct *tsec;
-       struct key_security_struct *ksec;
-
-       ksec = kzalloc(sizeof(struct key_security_struct), GFP_KERNEL);
-       if (!ksec)
-               return -ENOMEM;
+       struct key_security_struct *ksec = selinux_key(k);
 
        tsec = selinux_cred(cred);
        if (tsec->keycreate_sid)
@@ -6675,18 +6671,9 @@ static int selinux_key_alloc(struct key *k, const struct cred *cred,
        else
                ksec->sid = tsec->sid;
 
-       k->security = ksec;
        return 0;
 }
 
-static void selinux_key_free(struct key *k)
-{
-       struct key_security_struct *ksec = k->security;
-
-       k->security = NULL;
-       kfree(ksec);
-}
-
 static int selinux_key_permission(key_ref_t key_ref,
                                  const struct cred *cred,
                                  enum key_need_perm need_perm)
@@ -6727,14 +6714,14 @@ static int selinux_key_permission(key_ref_t key_ref,
 
        sid = cred_sid(cred);
        key = key_ref_to_ptr(key_ref);
-       ksec = key->security;
+       ksec = selinux_key(key);
 
        return avc_has_perm(sid, ksec->sid, SECCLASS_KEY, perm, NULL);
 }
 
 static int selinux_key_getsecurity(struct key *key, char **_buffer)
 {
-       struct key_security_struct *ksec = key->security;
+       struct key_security_struct *ksec = selinux_key(key);
        char *context = NULL;
        unsigned len;
        int rc;
@@ -6986,6 +6973,7 @@ struct lsm_blob_sizes selinux_blob_sizes __ro_after_init = {
        .lbs_file = sizeof(struct file_security_struct),
        .lbs_inode = sizeof(struct inode_security_struct),
        .lbs_ipc = sizeof(struct ipc_security_struct),
+       .lbs_key = sizeof(struct key_security_struct),
        .lbs_msg_msg = sizeof(struct msg_security_struct),
        .lbs_sock = sizeof(struct sk_security_struct),
        .lbs_superblock = sizeof(struct superblock_security_struct),
@@ -7324,7 +7312,6 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = {
 #endif
 
 #ifdef CONFIG_KEYS
-       LSM_HOOK_INIT(key_free, selinux_key_free),
        LSM_HOOK_INIT(key_permission, selinux_key_permission),
        LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
 #ifdef CONFIG_KEY_NOTIFICATIONS

diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index b074099acbaf79deffa9b73cb01a176dfbe13a77..83b9443d6919034d7cad7a9d725108236be3a724 100644 (file)
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -195,6 +195,13 @@ selinux_superblock(const struct super_block *superblock)
        return superblock->s_security + selinux_blob_sizes.lbs_superblock;
 }
 
+#ifdef CONFIG_KEYS
+static inline struct key_security_struct *selinux_key(const struct key *key)
+{
+       return key->security + selinux_blob_sizes.lbs_key;
+}
+#endif /* CONFIG_KEYS */
+
 static inline struct sk_security_struct *selinux_sock(const struct sock *sock)
 {
        return sock->sk_security + selinux_blob_sizes.lbs_sock;

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 297f21446f45685f5ad2b01f73c21ce73975769b..dbf8d7226eb56a3385ec33e4eabf7b00a115ad5a 100644 (file)
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -360,6 +360,13 @@ static inline struct socket_smack *smack_sock(const struct sock *sock)
        return sock->sk_security + smack_blob_sizes.lbs_sock;
 }
 
+#ifdef CONFIG_KEYS
+static inline struct smack_known **smack_key(const struct key *key)
+{
+       return key->security + smack_blob_sizes.lbs_key;
+}
+#endif /* CONFIG_KEYS */
+
 /*
  * Is the directory transmuting?
  */

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 742ccbd67a579ee0dde6e40772f460ddc55b5b67..d690bfda893ac6abd05d4f519e948c15b00a2f01 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4504,23 +4504,13 @@ static void smack_inet_csk_clone(struct sock *sk,
 static int smack_key_alloc(struct key *key, const struct cred *cred,
                           unsigned long flags)
 {
+       struct smack_known **blob = smack_key(key);
        struct smack_known *skp = smk_of_task(smack_cred(cred));
 
-       key->security = skp;
+       *blob = skp;
        return 0;
 }
 
-/**
- * smack_key_free - Clear the key security blob
- * @key: the object
- *
- * Clear the blob pointer
- */
-static void smack_key_free(struct key *key)
-{
-       key->security = NULL;
-}
-
 /**
  * smack_key_permission - Smack access on a key
  * @key_ref: gets to the object
@@ -4534,6 +4524,8 @@ static int smack_key_permission(key_ref_t key_ref,
                                const struct cred *cred,
                                enum key_need_perm need_perm)
 {
+       struct smack_known **blob;
+       struct smack_known *skp;
        struct key *keyp;
        struct smk_audit_info ad;
        struct smack_known *tkp = smk_of_task(smack_cred(cred));
@@ -4571,7 +4563,9 @@ static int smack_key_permission(key_ref_t key_ref,
         * If the key hasn't been initialized give it access so that
         * it may do so.
         */
-       if (keyp->security == NULL)
+       blob = smack_key(keyp);
+       skp = *blob;
+       if (skp == NULL)
                return 0;
        /*
         * This should not occur
@@ -4587,8 +4581,8 @@ static int smack_key_permission(key_ref_t key_ref,
        ad.a.u.key_struct.key = keyp->serial;
        ad.a.u.key_struct.key_desc = keyp->description;
 #endif
-       rc = smk_access(tkp, keyp->security, request, &ad);
-       rc = smk_bu_note("key access", tkp, keyp->security, request, rc);
+       rc = smk_access(tkp, skp, request, &ad);
+       rc = smk_bu_note("key access", tkp, skp, request, rc);
        return rc;
 }
 
@@ -4603,11 +4597,12 @@ static int smack_key_permission(key_ref_t key_ref,
  */
 static int smack_key_getsecurity(struct key *key, char **_buffer)
 {
-       struct smack_known *skp = key->security;
+       struct smack_known **blob = smack_key(key);
+       struct smack_known *skp = *blob;
        size_t length;
        char *copy;
 
-       if (key->security == NULL) {
+       if (skp == NULL) {
                *_buffer = NULL;
                return 0;
        }
@@ -5041,6 +5036,7 @@ struct lsm_blob_sizes smack_blob_sizes __ro_after_init = {
        .lbs_file = sizeof(struct smack_known *),
        .lbs_inode = sizeof(struct inode_smack),
        .lbs_ipc = sizeof(struct smack_known *),
+       .lbs_key = sizeof(struct smack_known *),
        .lbs_msg_msg = sizeof(struct smack_known *),
        .lbs_sock = sizeof(struct socket_smack),
        .lbs_superblock = sizeof(struct superblock_smack),
@@ -5178,7 +5174,6 @@ static struct security_hook_list smack_hooks[] __ro_after_init = {
  /* key management security hooks */
 #ifdef CONFIG_KEYS
        LSM_HOOK_INIT(key_alloc, smack_key_alloc),
-       LSM_HOOK_INIT(key_free, smack_key_free),
        LSM_HOOK_INIT(key_permission, smack_key_permission),
        LSM_HOOK_INIT(key_getsecurity, smack_key_getsecurity),
 #ifdef CONFIG_KEY_NOTIFICATIONS