// SPDX-License-Identifier: GPL-2.0-or-later /* Keyring handling * * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved. * Written by David Howells ([email protected]) */ #include <linux/export.h> #include <linux/init.h> #include <linux/sched.h> #include <linux/slab.h> #include <linux/security.h> #include <linux/seq_file.h> #include <linux/err.h> #include <linux/user_namespace.h> #include <linux/nsproxy.h> #include <keys/keyring-type.h> #include <keys/user-type.h> #include <linux/assoc_array_priv.h> #include <linux/uaccess.h> #include <net/net_namespace.h> #include "internal.h" /* * When plumbing the depths of the key tree, this sets a hard limit * set on how deep we're willing to go. */ #define KEYRING_SEARCH_MAX_DEPTH … /* * We mark pointers we pass to the associative array with bit 1 set if * they're keyrings and clear otherwise. */ #define KEYRING_PTR_SUBTYPE … static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x) { … } static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x) { … } static inline void *keyring_key_to_ptr(struct key *key) { … } static DEFINE_RWLOCK(keyring_name_lock); /* * Clean up the bits of user_namespace that belong to us. */ void key_free_user_ns(struct user_namespace *ns) { … } /* * The keyring key type definition. Keyrings are simply keys of this type and * can be treated as ordinary keys in addition to having their own special * operations. */ static int keyring_preparse(struct key_preparsed_payload *prep); static void keyring_free_preparse(struct key_preparsed_payload *prep); static int keyring_instantiate(struct key *keyring, struct key_preparsed_payload *prep); static void keyring_revoke(struct key *keyring); static void keyring_destroy(struct key *keyring); static void keyring_describe(const struct key *keyring, struct seq_file *m); static long keyring_read(const struct key *keyring, char *buffer, size_t buflen); struct key_type key_type_keyring = …; EXPORT_SYMBOL(…); /* * Semaphore to serialise link/link calls to prevent two link calls in parallel * introducing a cycle. */ static DEFINE_MUTEX(keyring_serialise_link_lock); /* * Publish the name of a keyring so that it can be found by name (if it has * one and it doesn't begin with a dot). */ static void keyring_publish_name(struct key *keyring) { … } /* * Preparse a keyring payload */ static int keyring_preparse(struct key_preparsed_payload *prep) { … } /* * Free a preparse of a user defined key payload */ static void keyring_free_preparse(struct key_preparsed_payload *prep) { … } /* * Initialise a keyring. * * Returns 0 on success, -EINVAL if given any data. */ static int keyring_instantiate(struct key *keyring, struct key_preparsed_payload *prep) { … } /* * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd * fold the carry back too, but that requires inline asm. */ static u64 mult_64x32_and_fold(u64 x, u32 y) { … } /* * Hash a key type and description. */ static void hash_key_type_and_desc(struct keyring_index_key *index_key) { … } /* * Finalise an index key to include a part of the description actually in the * index key, to set the domain tag and to calculate the hash. */ void key_set_index_key(struct keyring_index_key *index_key) { … } /** * key_put_tag - Release a ref on a tag. * @tag: The tag to release. * * This releases a reference the given tag and returns true if that ref was the * last one. */ bool key_put_tag(struct key_tag *tag) { … } /** * key_remove_domain - Kill off a key domain and gc its keys * @domain_tag: The domain tag to release. * * This marks a domain tag as being dead and releases a ref on it. If that * wasn't the last reference, the garbage collector is poked to try and delete * all keys that were in the domain. */ void key_remove_domain(struct key_tag *domain_tag) { … } /* * Build the next index key chunk. * * We return it one word-sized chunk at a time. */ static unsigned long keyring_get_key_chunk(const void *data, int level) { … } static unsigned long keyring_get_object_key_chunk(const void *object, int level) { … } static bool keyring_compare_object(const void *object, const void *data) { … } /* * Compare the index keys of a pair of objects and determine the bit position * at which they differ - if they differ. */ static int keyring_diff_objects(const void *object, const void *data) { … } /* * Free an object after stripping the keyring flag off of the pointer. */ static void keyring_free_object(void *object) { … } /* * Operations for keyring management by the index-tree routines. */ static const struct assoc_array_ops keyring_assoc_array_ops = …; /* * Clean up a keyring when it is destroyed. Unpublish its name if it had one * and dispose of its data. * * The garbage collector detects the final key_put(), removes the keyring from * the serial number tree and then does RCU synchronisation before coming here, * so we shouldn't need to worry about code poking around here with the RCU * readlock held by this time. */ static void keyring_destroy(struct key *keyring) { … } /* * Describe a keyring for /proc. */ static void keyring_describe(const struct key *keyring, struct seq_file *m) { … } struct keyring_read_iterator_context { … }; static int keyring_read_iterator(const void *object, void *data) { … } /* * Read a list of key IDs from the keyring's contents in binary form * * The keyring's semaphore is read-locked by the caller. This prevents someone * from modifying it under us - which could cause us to read key IDs multiple * times. */ static long keyring_read(const struct key *keyring, char *buffer, size_t buflen) { … } /* * Allocate a keyring and link into the destination 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_restriction *restrict_link, struct key *dest) { … } EXPORT_SYMBOL(…); /** * 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. * @restriction_key: Keys providing additional data for evaluating restriction. * * 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 stored in a key_restriction structure which is passed * in the restrict_link parameter to keyring_alloc(). */ int restrict_link_reject(struct key *keyring, const struct key_type *type, const union key_payload *payload, struct key *restriction_key) { … } /* * By default, we keys found by getting an exact match on their descriptions. */ bool key_default_cmp(const struct key *key, const struct key_match_data *match_data) { … } /* * Iteration function to consider each key found. */ static int keyring_search_iterator(const void *object, void *iterator_data) { … } /* * Search inside a keyring for a key. We can search by walking to it * directly based on its index-key or we can iterate over the entire * tree looking for it, based on the match function. */ static int search_keyring(struct key *keyring, struct keyring_search_context *ctx) { … } /* * Search a tree of keyrings that point to other keyrings up to the maximum * depth. */ static bool search_nested_keyrings(struct key *keyring, struct keyring_search_context *ctx) { … } /** * keyring_search_rcu - Search a keyring tree for a matching key under RCU * @keyring_ref: A pointer to the keyring with possession indicator. * @ctx: The keyring search context. * * Search the supplied keyring tree for a key that matches the criteria given. * The root keyring and any linked keyrings must grant Search permission to the * caller to be searchable and keys can only be found if they too grant Search * to the caller. The possession flag on the root keyring pointer controls use * of the possessor bits in permissions checking of the entire tree. In * addition, the LSM gets to forbid keyring searches and key matches. * * The search is performed as a breadth-then-depth search up to the prescribed * limit (KEYRING_SEARCH_MAX_DEPTH). The caller must hold the RCU read lock to * prevent keyrings from being destroyed or rearranged whilst they are being * searched. * * Keys are matched to the type provided and are then filtered by the match * function, which is given the description to use in any way it sees fit. The * match function may use any attributes of a key that it wishes to * determine the match. Normally the match function from the key type would be * used. * * RCU can be used to prevent the keyring key lists from disappearing without * the need to take lots of locks. * * Returns a pointer to the found key and increments the key usage count if * successful; -EAGAIN if no matching keys were found, or if expired or revoked * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the * specified keyring wasn't a keyring. * * In the case of a successful return, the possession attribute from * @keyring_ref is propagated to the returned key reference. */ key_ref_t keyring_search_rcu(key_ref_t keyring_ref, struct keyring_search_context *ctx) { … } /** * keyring_search - Search the supplied keyring tree for a matching key * @keyring: The root of the keyring tree to be searched. * @type: The type of keyring we want to find. * @description: The name of the keyring we want to find. * @recurse: True to search the children of @keyring also * * As keyring_search_rcu() above, but using the current task's credentials and * type's default matching function and preferred search method. */ key_ref_t keyring_search(key_ref_t keyring, struct key_type *type, const char *description, bool recurse) { … } EXPORT_SYMBOL(…); static struct key_restriction *keyring_restriction_alloc( key_restrict_link_func_t check) { … } /* * Semaphore to serialise restriction setup to prevent reference count * cycles through restriction key pointers. */ static DECLARE_RWSEM(keyring_serialise_restrict_sem); /* * Check for restriction cycles that would prevent keyring garbage collection. * keyring_serialise_restrict_sem must be held. */ static bool keyring_detect_restriction_cycle(const struct key *dest_keyring, struct key_restriction *keyres) { … } /** * keyring_restrict - Look up and apply a restriction to a keyring * @keyring_ref: The keyring to be restricted * @type: The key type that will provide the restriction checker. * @restriction: The restriction options to apply to the keyring * * Look up a keyring and apply a restriction to it. The restriction is managed * by the specific key type, but can be configured by the options specified in * the restriction string. */ int keyring_restrict(key_ref_t keyring_ref, const char *type, const char *restriction) { … } EXPORT_SYMBOL(…); /* * Search the given keyring for a key that might be updated. * * The caller must guarantee that the keyring is a keyring and that the * permission is granted to modify the keyring as no check is made here. The * caller must also hold a lock on the keyring semaphore. * * Returns a pointer to the found key with usage count incremented if * successful and returns NULL if not found. Revoked and invalidated keys are * skipped over. * * If successful, the possession indicator is propagated from the keyring ref * to the returned key reference. */ key_ref_t find_key_to_update(key_ref_t keyring_ref, const struct keyring_index_key *index_key) { … } /* * Find a keyring with the specified name. * * Only keyrings that have nonzero refcount, are not revoked, and are owned by a * user in the current user namespace are considered. If @uid_keyring is %true, * the keyring additionally must have been allocated as a user or user session * keyring; otherwise, it must grant Search permission directly to the caller. * * Returns a pointer to the keyring with the keyring's refcount having being * incremented on success. -ENOKEY is returned if a key could not be found. */ struct key *find_keyring_by_name(const char *name, bool uid_keyring) { … } static int keyring_detect_cycle_iterator(const void *object, void *iterator_data) { … } /* * See if a cycle will be created by inserting acyclic tree B in acyclic * tree A at the topmost level (ie: as a direct child of A). * * Since we are adding B to A at the top level, checking for cycles should just * be a matter of seeing if node A is somewhere in tree B. */ static int keyring_detect_cycle(struct key *A, struct key *B) { … } /* * Lock keyring for link. */ int __key_link_lock(struct key *keyring, const struct keyring_index_key *index_key) __acquires(&keyring->sem) __acquires(&keyring_serialise_link_lock) { … } /* * Lock keyrings for move (link/unlink combination). */ int __key_move_lock(struct key *l_keyring, struct key *u_keyring, const struct keyring_index_key *index_key) __acquires(&l_keyring->sem) __acquires(&u_keyring->sem) __acquires(&keyring_serialise_link_lock) { … } /* * Preallocate memory so that a key can be linked into to a keyring. */ int __key_link_begin(struct key *keyring, const struct keyring_index_key *index_key, struct assoc_array_edit **_edit) { … } /* * Check already instantiated keys aren't going to be a problem. * * The caller must have called __key_link_begin(). Don't need to call this for * keys that were created since __key_link_begin() was called. */ int __key_link_check_live_key(struct key *keyring, struct key *key) { … } /* * Link a key into to a keyring. * * Must be called with __key_link_begin() having being called. Discards any * already extant link to matching key if there is one, so that each keyring * holds at most one link to any given key of a particular type+description * combination. */ void __key_link(struct key *keyring, struct key *key, struct assoc_array_edit **_edit) { … } /* * Finish linking a key into to a keyring. * * Must be called with __key_link_begin() having being called. */ void __key_link_end(struct key *keyring, const struct keyring_index_key *index_key, struct assoc_array_edit *edit) __releases(&keyring->sem) __releases(&keyring_serialise_link_lock) { … } /* * Check addition of keys to restricted keyrings. */ static int __key_link_check_restriction(struct key *keyring, struct key *key) { … } /** * key_link - Link a key to a keyring * @keyring: The keyring to make the link in. * @key: The key to link to. * * Make a link in a keyring to a key, such that the keyring holds a reference * on that key and the key can potentially be found by searching that keyring. * * This function will write-lock the keyring's semaphore and will consume some * of the user's key data quota to hold the link. * * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is * full, -EDQUOT if there is insufficient key data quota remaining to add * another link or -ENOMEM if there's insufficient memory. * * It is assumed that the caller has checked that it is permitted for a link to * be made (the keyring should have Write permission and the key Link * permission). */ int key_link(struct key *keyring, struct key *key) { … } EXPORT_SYMBOL(…); /* * Lock a keyring for unlink. */ static int __key_unlink_lock(struct key *keyring) __acquires(&keyring->sem) { … } /* * Begin the process of unlinking a key from a keyring. */ static int __key_unlink_begin(struct key *keyring, struct key *key, struct assoc_array_edit **_edit) { … } /* * Apply an unlink change. */ static void __key_unlink(struct key *keyring, struct key *key, struct assoc_array_edit **_edit) { … } /* * Finish unlinking a key from to a keyring. */ static void __key_unlink_end(struct key *keyring, struct key *key, struct assoc_array_edit *edit) __releases(&keyring->sem) { … } /** * key_unlink - Unlink the first link to a key from a keyring. * @keyring: The keyring to remove the link from. * @key: The key the link is to. * * Remove a link from a keyring to a key. * * This function will write-lock the keyring's semaphore. * * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if * the key isn't linked to by the keyring or -ENOMEM if there's insufficient * memory. * * It is assumed that the caller has checked that it is permitted for a link to * be removed (the keyring should have Write permission; no permissions are * required on the key). */ int key_unlink(struct key *keyring, struct key *key) { … } EXPORT_SYMBOL(…); /** * key_move - Move a key from one keyring to another * @key: The key to move * @from_keyring: The keyring to remove the link from. * @to_keyring: The keyring to make the link in. * @flags: Qualifying flags, such as KEYCTL_MOVE_EXCL. * * Make a link in @to_keyring to a key, such that the keyring holds a reference * on that key and the key can potentially be found by searching that keyring * whilst simultaneously removing a link to the key from @from_keyring. * * This function will write-lock both keyring's semaphores and will consume * some of the user's key data quota to hold the link on @to_keyring. * * Returns 0 if successful, -ENOTDIR if either keyring isn't a keyring, * -EKEYREVOKED if either keyring has been revoked, -ENFILE if the second * keyring is full, -EDQUOT if there is insufficient key data quota remaining * to add another link or -ENOMEM if there's insufficient memory. If * KEYCTL_MOVE_EXCL is set, then -EEXIST will be returned if there's already a * matching key in @to_keyring. * * It is assumed that the caller has checked that it is permitted for a link to * be made (the keyring should have Write permission and the key Link * permission). */ int key_move(struct key *key, struct key *from_keyring, struct key *to_keyring, unsigned int flags) { … } EXPORT_SYMBOL(…); /** * keyring_clear - Clear a keyring * @keyring: The keyring to clear. * * Clear the contents of the specified keyring. * * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. */ int keyring_clear(struct key *keyring) { … } EXPORT_SYMBOL(…); /* * Dispose of the links from a revoked keyring. * * This is called with the key sem write-locked. */ static void keyring_revoke(struct key *keyring) { … } static bool keyring_gc_select_iterator(void *object, void *iterator_data) { … } static int keyring_gc_check_iterator(const void *object, void *iterator_data) { … } /* * Garbage collect pointers from a keyring. * * Not called with any locks held. The keyring's key struct will not be * deallocated under us as only our caller may deallocate it. */ void keyring_gc(struct key *keyring, time64_t limit) { … } /* * Garbage collect restriction pointers from a keyring. * * Keyring restrictions are associated with a key type, and must be cleaned * up if the key type is unregistered. The restriction is altered to always * reject additional keys so a keyring cannot be opened up by unregistering * a key type. * * Not called with any keyring locks held. The keyring's key struct will not * be deallocated under us as only our caller may deallocate it. * * The caller is required to hold key_types_sem and dead_type->sem. This is * fulfilled by key_gc_keytype() holding the locks on behalf of * key_garbage_collector(), which it invokes on a workqueue. */ void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type) { … }
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