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-rw-r--r--Documentation/security/keys.txt65
1 files changed, 52 insertions, 13 deletions
diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt
index 8727c194ca16..821c936e1a63 100644
--- a/Documentation/security/keys.txt
+++ b/Documentation/security/keys.txt
@@ -888,11 +888,11 @@ payload contents" for more information.
const char *callout_info);
This is used to request a key or keyring with a description that matches
- the description specified according to the key type's match function. This
- permits approximate matching to occur. If callout_string is not NULL, then
- /sbin/request-key will be invoked in an attempt to obtain the key from
- userspace. In that case, callout_string will be passed as an argument to
- the program.
+ the description specified according to the key type's match_preparse()
+ method. This permits approximate matching to occur. If callout_string is
+ not NULL, then /sbin/request-key will be invoked in an attempt to obtain
+ the key from userspace. In that case, callout_string will be passed as an
+ argument to the program.
Should the function fail error ENOKEY, EKEYEXPIRED or EKEYREVOKED will be
returned.
@@ -1170,7 +1170,7 @@ The structure has a number of fields, some of which are mandatory:
The method should return 0 if successful or a negative error code
otherwise.
-
+
(*) void (*free_preparse)(struct key_preparsed_payload *prep);
This method is only required if the preparse() method is provided,
@@ -1225,16 +1225,55 @@ The structure has a number of fields, some of which are mandatory:
It is safe to sleep in this method.
- (*) int (*match)(const struct key *key, const void *desc);
+ (*) int (*match_preparse)(struct key_match_data *match_data);
+
+ This method is optional. It is called when a key search is about to be
+ performed. It is given the following structure:
- This method is called to match a key against a description. It should
- return non-zero if the two match, zero if they don't.
+ struct key_match_data {
+ bool (*cmp)(const struct key *key,
+ const struct key_match_data *match_data);
+ const void *raw_data;
+ void *preparsed;
+ unsigned lookup_type;
+ };
- This method should not need to lock the key in any way. The type and
- description can be considered invariant, and the payload should not be
- accessed (the key may not yet be instantiated).
+ On entry, raw_data will be pointing to the criteria to be used in matching
+ a key by the caller and should not be modified. (*cmp)() will be pointing
+ to the default matcher function (which does an exact description match
+ against raw_data) and lookup_type will be set to indicate a direct lookup.
- It is not safe to sleep in this method; the caller may hold spinlocks.
+ The following lookup_type values are available:
+
+ [*] KEYRING_SEARCH_LOOKUP_DIRECT - A direct lookup hashes the type and
+ description to narrow down the search to a small number of keys.
+
+ [*] KEYRING_SEARCH_LOOKUP_ITERATE - An iterative lookup walks all the
+ keys in the keyring until one is matched. This must be used for any
+ search that's not doing a simple direct match on the key description.
+
+ The method may set cmp to point to a function of its choice that does some
+ other form of match, may set lookup_type to KEYRING_SEARCH_LOOKUP_ITERATE
+ and may attach something to the preparsed pointer for use by (*cmp)().
+ (*cmp)() should return true if a key matches and false otherwise.
+
+ If preparsed is set, it may be necessary to use the match_free() method to
+ clean it up.
+
+ The method should return 0 if successful or a negative error code
+ otherwise.
+
+ It is permitted to sleep in this method, but (*cmp)() may not sleep as
+ locks will be held over it.
+
+ If match_preparse() is not provided, keys of this type will be matched
+ exactly by their description.
+
+
+ (*) void (*match_free)(struct key_match_data *match_data);
+
+ This method is optional. If given, it called to clean up
+ match_data->preparsed after a successful call to match_preparse().
(*) void (*revoke)(struct key *key);