Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull security subsystem updates from James Morris:
 "Highlights:

   - A new LSM, "LoadPin", from Kees Cook is added, which allows forcing
     of modules and firmware to be loaded from a specific device (this
     is from ChromeOS, where the device as a whole is verified
     cryptographically via dm-verity).

     This is disabled by default but can be configured to be enabled by
     default (don't do this if you don't know what you're doing).

   - Keys: allow authentication data to be stored in an asymmetric key.
     Lots of general fixes and updates.

   - SELinux: add restrictions for loading of kernel modules via
     finit_module().  Distinguish non-init user namespace capability
     checks.  Apply execstack check on thread stacks"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (48 commits)
  LSM: LoadPin: provide enablement CONFIG
  Yama: use atomic allocations when reporting
  seccomp: Fix comment typo
  ima: add support for creating files using the mknodat syscall
  ima: fix ima_inode_post_setattr
  vfs: forbid write access when reading a file into memory
  fs: fix over-zealous use of "const"
  selinux: apply execstack check on thread stacks
  selinux: distinguish non-init user namespace capability checks
  LSM: LoadPin for kernel file loading restrictions
  fs: define a string representation of the kernel_read_file_id enumeration
  Yama: consolidate error reporting
  string_helpers: add kstrdup_quotable_file
  string_helpers: add kstrdup_quotable_cmdline
  string_helpers: add kstrdup_quotable
  selinux: check ss_initialized before revalidating an inode label
  selinux: delay inode label lookup as long as possible
  selinux: don't revalidate an inode's label when explicitly setting it
  selinux: Change bool variable name to index.
  KEYS: Add KEYCTL_DH_COMPUTE command
  ...

1 files changed, 39 insertions, 7 deletions

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index f931ccfeefb0..c91e4e0cea08 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -491,13 +491,17 @@ static long keyring_read(const struct key *keyring,
  */
 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 			  const struct cred *cred, key_perm_t perm,
-			  unsigned long flags, struct key *dest)
+			  unsigned long flags,
+			  int (*restrict_link)(struct key *,
+					       const struct key_type *,
+					       const union key_payload *),
+			  struct key *dest)
 {
 	struct key *keyring;
 	int ret;
 
 	keyring = key_alloc(&key_type_keyring, description,
-			    uid, gid, cred, perm, flags);
+			    uid, gid, cred, perm, flags, restrict_link);
 	if (!IS_ERR(keyring)) {
 		ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
 		if (ret < 0) {
@@ -510,6 +514,26 @@ struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 }
 EXPORT_SYMBOL(keyring_alloc);
 
+/**
+ * restrict_link_reject - Give -EPERM to restrict link
+ * @keyring: The keyring being added to.
+ * @type: The type of key being added.
+ * @payload: The payload of the key intended to be added.
+ *
+ * Reject the addition of any links to a keyring.  It can be overridden by
+ * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
+ * adding a key to a keyring.
+ *
+ * This is meant to be passed as the restrict_link parameter to
+ * keyring_alloc().
+ */
+int restrict_link_reject(struct key *keyring,
+			 const struct key_type *type,
+			 const union key_payload *payload)
+{
+	return -EPERM;
+}
+
 /*
  * By default, we keys found by getting an exact match on their descriptions.
  */
@@ -1191,6 +1215,16 @@ void __key_link_end(struct key *keyring,
 	up_write(&keyring->sem);
 }
 
+/*
+ * Check addition of keys to restricted keyrings.
+ */
+static int __key_link_check_restriction(struct key *keyring, struct key *key)
+{
+	if (!keyring->restrict_link)
+		return 0;
+	return keyring->restrict_link(keyring, key->type, &key->payload);
+}
+
 /**
  * key_link - Link a key to a keyring
  * @keyring: The keyring to make the link in.
@@ -1221,14 +1255,12 @@ int key_link(struct key *keyring, struct key *key)
 	key_check(keyring);
 	key_check(key);
 
-	if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
-	    !test_bit(KEY_FLAG_TRUSTED, &key->flags))
-		return -EPERM;
-
 	ret = __key_link_begin(keyring, &key->index_key, &edit);
 	if (ret == 0) {
 		kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
-		ret = __key_link_check_live_key(keyring, key);
+		ret = __key_link_check_restriction(keyring, key);
+		if (ret == 0)
+			ret = __key_link_check_live_key(keyring, key);
 		if (ret == 0)
 			__key_link(key, &edit);
 		__key_link_end(keyring, &key->index_key, edit);