[PATCH v14 04/10] KEYS: Move KEY_LOOKUP_ to include/linux/key.h and add flags check function

[Roberto Sassu <roberto.sassu@huaweicloud.com>]

From: Roberto Sassu <roberto.sassu@huawei.com>

In preparation for the patch that introduces the bpf_lookup_user_key() eBPF
kfunc, move KEY_LOOKUP_ definitions to include/linux/key.h, to be able to
validate the kfunc parameters.

Also, introduce key_lookup_flags_valid() to check if the caller set in the
argument only defined flags. Introduce it directly in include/linux/key.h,
to reduce the risk that the check is not in sync with currently defined
flags.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: KP Singh <kpsingh@kernel.org>
---
 include/linux/key.h      | 16 ++++++++++++++++
 security/keys/internal.h |  2 --
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/linux/key.h b/include/linux/key.h
index 7febc4881363..e679dbf0c940 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -88,6 +88,22 @@ enum key_need_perm {
 	KEY_DEFER_PERM_CHECK,	/* Special: permission check is deferred */
 };
 
+#define KEY_LOOKUP_CREATE	0x01
+#define KEY_LOOKUP_PARTIAL	0x02
+
+/**
+ * key_lookup_flags_valid - detect if provided key lookup flags are valid
+ * @flags: key lookup flags.
+ *
+ * Verify whether or not the caller set in the argument only defined flags.
+ *
+ * Return: true if flags are valid, false if not.
+ */
+static inline bool key_lookup_flags_valid(u64 flags)
+{
+	return !(flags & ~(KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL));
+}
+
 struct seq_file;
 struct user_struct;
 struct signal_struct;
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 9b9cf3b6fcbb..3c1e7122076b 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -165,8 +165,6 @@ extern struct key *request_key_and_link(struct key_type *type,
 
 extern bool lookup_user_key_possessed(const struct key *key,
 				      const struct key_match_data *match_data);
-#define KEY_LOOKUP_CREATE	0x01
-#define KEY_LOOKUP_PARTIAL	0x02
 
 extern long join_session_keyring(const char *name);
 extern void key_change_session_keyring(struct callback_head *twork);
-- 
2.25.1