linux/security/keys/keyring.c
Linus Torvalds 028db3e290 Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs"
This reverts merge 0f75ef6a9c (and thus
effectively commits

   7a1ade8475 ("keys: Provide KEYCTL_GRANT_PERMISSION")
   2e12256b9a ("keys: Replace uid/gid/perm permissions checking with an ACL")

that the merge brought in).

It turns out that it breaks booting with an encrypted volume, and Eric
biggers reports that it also breaks the fscrypt tests [1] and loading of
in-kernel X.509 certificates [2].

The root cause of all the breakage is likely the same, but David Howells
is off email so rather than try to work it out it's getting reverted in
order to not impact the rest of the merge window.

 [1] https://lore.kernel.org/lkml/20190710011559.GA7973@sol.localdomain/
 [2] https://lore.kernel.org/lkml/20190710013225.GB7973@sol.localdomain/

Link: https://lore.kernel.org/lkml/CAHk-=wjxoeMJfeBahnWH=9zShKp2bsVy527vo3_y8HfOdhwAAw@mail.gmail.com/
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-10 18:43:43 -07:00

1793 lines
48 KiB
C

// 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 (dhowells@redhat.com)
*/
#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 6
/*
* We mark pointers we pass to the associative array with bit 1 set if
* they're keyrings and clear otherwise.
*/
#define KEYRING_PTR_SUBTYPE 0x2UL
static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x)
{
return (unsigned long)x & KEYRING_PTR_SUBTYPE;
}
static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x)
{
void *object = assoc_array_ptr_to_leaf(x);
return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE);
}
static inline void *keyring_key_to_ptr(struct key *key)
{
if (key->type == &key_type_keyring)
return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE);
return 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)
{
write_lock(&keyring_name_lock);
list_del_init(&ns->keyring_name_list);
write_unlock(&keyring_name_lock);
key_put(ns->user_keyring_register);
#ifdef CONFIG_PERSISTENT_KEYRINGS
key_put(ns->persistent_keyring_register);
#endif
}
/*
* 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 __user *buffer, size_t buflen);
struct key_type key_type_keyring = {
.name = "keyring",
.def_datalen = 0,
.preparse = keyring_preparse,
.free_preparse = keyring_free_preparse,
.instantiate = keyring_instantiate,
.revoke = keyring_revoke,
.destroy = keyring_destroy,
.describe = keyring_describe,
.read = keyring_read,
};
EXPORT_SYMBOL(key_type_keyring);
/*
* 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)
{
struct user_namespace *ns = current_user_ns();
if (keyring->description &&
keyring->description[0] &&
keyring->description[0] != '.') {
write_lock(&keyring_name_lock);
list_add_tail(&keyring->name_link, &ns->keyring_name_list);
write_unlock(&keyring_name_lock);
}
}
/*
* Preparse a keyring payload
*/
static int keyring_preparse(struct key_preparsed_payload *prep)
{
return prep->datalen != 0 ? -EINVAL : 0;
}
/*
* 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)
{
assoc_array_init(&keyring->keys);
/* make the keyring available by name if it has one */
keyring_publish_name(keyring);
return 0;
}
/*
* 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)
{
u64 hi = (u64)(u32)(x >> 32) * y;
u64 lo = (u64)(u32)(x) * y;
return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
}
/*
* Hash a key type and description.
*/
static void hash_key_type_and_desc(struct keyring_index_key *index_key)
{
const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
const char *description = index_key->description;
unsigned long hash, type;
u32 piece;
u64 acc;
int n, desc_len = index_key->desc_len;
type = (unsigned long)index_key->type;
acc = mult_64x32_and_fold(type, desc_len + 13);
acc = mult_64x32_and_fold(acc, 9207);
piece = (unsigned long)index_key->domain_tag;
acc = mult_64x32_and_fold(acc, piece);
acc = mult_64x32_and_fold(acc, 9207);
for (;;) {
n = desc_len;
if (n <= 0)
break;
if (n > 4)
n = 4;
piece = 0;
memcpy(&piece, description, n);
description += n;
desc_len -= n;
acc = mult_64x32_and_fold(acc, piece);
acc = mult_64x32_and_fold(acc, 9207);
}
/* Fold the hash down to 32 bits if need be. */
hash = acc;
if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
hash ^= acc >> 32;
/* Squidge all the keyrings into a separate part of the tree to
* ordinary keys by making sure the lowest level segment in the hash is
* zero for keyrings and non-zero otherwise.
*/
if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
hash |= (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
else if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
hash = (hash + (hash << level_shift)) & ~fan_mask;
index_key->hash = hash;
}
/*
* 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)
{
static struct key_tag default_domain_tag = { .usage = REFCOUNT_INIT(1), };
size_t n = min_t(size_t, index_key->desc_len, sizeof(index_key->desc));
memcpy(index_key->desc, index_key->description, n);
if (!index_key->domain_tag) {
if (index_key->type->flags & KEY_TYPE_NET_DOMAIN)
index_key->domain_tag = current->nsproxy->net_ns->key_domain;
else
index_key->domain_tag = &default_domain_tag;
}
hash_key_type_and_desc(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)
{
if (refcount_dec_and_test(&tag->usage)) {
kfree_rcu(tag, rcu);
return true;
}
return false;
}
/**
* 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)
{
domain_tag->removed = true;
if (!key_put_tag(domain_tag))
key_schedule_gc_links();
}
/*
* 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)
{
const struct keyring_index_key *index_key = data;
unsigned long chunk = 0;
const u8 *d;
int desc_len = index_key->desc_len, n = sizeof(chunk);
level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
switch (level) {
case 0:
return index_key->hash;
case 1:
return index_key->x;
case 2:
return (unsigned long)index_key->type;
case 3:
return (unsigned long)index_key->domain_tag;
default:
level -= 4;
if (desc_len <= sizeof(index_key->desc))
return 0;
d = index_key->description + sizeof(index_key->desc);
d += level * sizeof(long);
desc_len -= sizeof(index_key->desc);
if (desc_len > n)
desc_len = n;
do {
chunk <<= 8;
chunk |= *d++;
} while (--desc_len > 0);
return chunk;
}
}
static unsigned long keyring_get_object_key_chunk(const void *object, int level)
{
const struct key *key = keyring_ptr_to_key(object);
return keyring_get_key_chunk(&key->index_key, level);
}
static bool keyring_compare_object(const void *object, const void *data)
{
const struct keyring_index_key *index_key = data;
const struct key *key = keyring_ptr_to_key(object);
return key->index_key.type == index_key->type &&
key->index_key.domain_tag == index_key->domain_tag &&
key->index_key.desc_len == index_key->desc_len &&
memcmp(key->index_key.description, index_key->description,
index_key->desc_len) == 0;
}
/*
* 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)
{
const struct key *key_a = keyring_ptr_to_key(object);
const struct keyring_index_key *a = &key_a->index_key;
const struct keyring_index_key *b = data;
unsigned long seg_a, seg_b;
int level, i;
level = 0;
seg_a = a->hash;
seg_b = b->hash;
if ((seg_a ^ seg_b) != 0)
goto differ;
level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
/* The number of bits contributed by the hash is controlled by a
* constant in the assoc_array headers. Everything else thereafter we
* can deal with as being machine word-size dependent.
*/
seg_a = a->x;
seg_b = b->x;
if ((seg_a ^ seg_b) != 0)
goto differ;
level += sizeof(unsigned long);
/* The next bit may not work on big endian */
seg_a = (unsigned long)a->type;
seg_b = (unsigned long)b->type;
if ((seg_a ^ seg_b) != 0)
goto differ;
level += sizeof(unsigned long);
seg_a = (unsigned long)a->domain_tag;
seg_b = (unsigned long)b->domain_tag;
if ((seg_a ^ seg_b) != 0)
goto differ;
level += sizeof(unsigned long);
i = sizeof(a->desc);
if (a->desc_len <= i)
goto same;
for (; i < a->desc_len; i++) {
seg_a = *(unsigned char *)(a->description + i);
seg_b = *(unsigned char *)(b->description + i);
if ((seg_a ^ seg_b) != 0)
goto differ_plus_i;
}
same:
return -1;
differ_plus_i:
level += i;
differ:
i = level * 8 + __ffs(seg_a ^ seg_b);
return i;
}
/*
* Free an object after stripping the keyring flag off of the pointer.
*/
static void keyring_free_object(void *object)
{
key_put(keyring_ptr_to_key(object));
}
/*
* Operations for keyring management by the index-tree routines.
*/
static const struct assoc_array_ops keyring_assoc_array_ops = {
.get_key_chunk = keyring_get_key_chunk,
.get_object_key_chunk = keyring_get_object_key_chunk,
.compare_object = keyring_compare_object,
.diff_objects = keyring_diff_objects,
.free_object = keyring_free_object,
};
/*
* 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)
{
if (keyring->description) {
write_lock(&keyring_name_lock);
if (keyring->name_link.next != NULL &&
!list_empty(&keyring->name_link))
list_del(&keyring->name_link);
write_unlock(&keyring_name_lock);
}
if (keyring->restrict_link) {
struct key_restriction *keyres = keyring->restrict_link;
key_put(keyres->key);
kfree(keyres);
}
assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
}
/*
* Describe a keyring for /proc.
*/
static void keyring_describe(const struct key *keyring, struct seq_file *m)
{
if (keyring->description)
seq_puts(m, keyring->description);
else
seq_puts(m, "[anon]");
if (key_is_positive(keyring)) {
if (keyring->keys.nr_leaves_on_tree != 0)
seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
else
seq_puts(m, ": empty");
}
}
struct keyring_read_iterator_context {
size_t buflen;
size_t count;
key_serial_t __user *buffer;
};
static int keyring_read_iterator(const void *object, void *data)
{
struct keyring_read_iterator_context *ctx = data;
const struct key *key = keyring_ptr_to_key(object);
int ret;
kenter("{%s,%d},,{%zu/%zu}",
key->type->name, key->serial, ctx->count, ctx->buflen);
if (ctx->count >= ctx->buflen)
return 1;
ret = put_user(key->serial, ctx->buffer);
if (ret < 0)
return ret;
ctx->buffer++;
ctx->count += sizeof(key->serial);
return 0;
}
/*
* 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 __user *buffer, size_t buflen)
{
struct keyring_read_iterator_context ctx;
long ret;
kenter("{%d},,%zu", key_serial(keyring), buflen);
if (buflen & (sizeof(key_serial_t) - 1))
return -EINVAL;
/* Copy as many key IDs as fit into the buffer */
if (buffer && buflen) {
ctx.buffer = (key_serial_t __user *)buffer;
ctx.buflen = buflen;
ctx.count = 0;
ret = assoc_array_iterate(&keyring->keys,
keyring_read_iterator, &ctx);
if (ret < 0) {
kleave(" = %ld [iterate]", ret);
return ret;
}
}
/* Return the size of the buffer needed */
ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
if (ret <= buflen)
kleave("= %ld [ok]", ret);
else
kleave("= %ld [buffer too small]", ret);
return ret;
}
/*
* 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)
{
struct key *keyring;
int ret;
keyring = key_alloc(&key_type_keyring, description,
uid, gid, cred, perm, flags, restrict_link);
if (!IS_ERR(keyring)) {
ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
if (ret < 0) {
key_put(keyring);
keyring = ERR_PTR(ret);
}
}
return keyring;
}
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.
* @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)
{
return -EPERM;
}
/*
* 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)
{
return strcmp(key->description, match_data->raw_data) == 0;
}
/*
* Iteration function to consider each key found.
*/
static int keyring_search_iterator(const void *object, void *iterator_data)
{
struct keyring_search_context *ctx = iterator_data;
const struct key *key = keyring_ptr_to_key(object);
unsigned long kflags = READ_ONCE(key->flags);
short state = READ_ONCE(key->state);
kenter("{%d}", key->serial);
/* ignore keys not of this type */
if (key->type != ctx->index_key.type) {
kleave(" = 0 [!type]");
return 0;
}
/* skip invalidated, revoked and expired keys */
if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
time64_t expiry = READ_ONCE(key->expiry);
if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED))) {
ctx->result = ERR_PTR(-EKEYREVOKED);
kleave(" = %d [invrev]", ctx->skipped_ret);
goto skipped;
}
if (expiry && ctx->now >= expiry) {
if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
ctx->result = ERR_PTR(-EKEYEXPIRED);
kleave(" = %d [expire]", ctx->skipped_ret);
goto skipped;
}
}
/* keys that don't match */
if (!ctx->match_data.cmp(key, &ctx->match_data)) {
kleave(" = 0 [!match]");
return 0;
}
/* key must have search permissions */
if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
key_task_permission(make_key_ref(key, ctx->possessed),
ctx->cred, KEY_NEED_SEARCH) < 0) {
ctx->result = ERR_PTR(-EACCES);
kleave(" = %d [!perm]", ctx->skipped_ret);
goto skipped;
}
if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
/* we set a different error code if we pass a negative key */
if (state < 0) {
ctx->result = ERR_PTR(state);
kleave(" = %d [neg]", ctx->skipped_ret);
goto skipped;
}
}
/* Found */
ctx->result = make_key_ref(key, ctx->possessed);
kleave(" = 1 [found]");
return 1;
skipped:
return ctx->skipped_ret;
}
/*
* 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)
{
if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
const void *object;
object = assoc_array_find(&keyring->keys,
&keyring_assoc_array_ops,
&ctx->index_key);
return object ? ctx->iterator(object, ctx) : 0;
}
return assoc_array_iterate(&keyring->keys, ctx->iterator, 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)
{
struct {
struct key *keyring;
struct assoc_array_node *node;
int slot;
} stack[KEYRING_SEARCH_MAX_DEPTH];
struct assoc_array_shortcut *shortcut;
struct assoc_array_node *node;
struct assoc_array_ptr *ptr;
struct key *key;
int sp = 0, slot;
kenter("{%d},{%s,%s}",
keyring->serial,
ctx->index_key.type->name,
ctx->index_key.description);
#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
(ctx->flags & STATE_CHECKS) == STATE_CHECKS);
if (ctx->index_key.description)
key_set_index_key(&ctx->index_key);
/* Check to see if this top-level keyring is what we are looking for
* and whether it is valid or not.
*/
if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
keyring_compare_object(keyring, &ctx->index_key)) {
ctx->skipped_ret = 2;
switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
case 1:
goto found;
case 2:
return false;
default:
break;
}
}
ctx->skipped_ret = 0;
/* Start processing a new keyring */
descend_to_keyring:
kdebug("descend to %d", keyring->serial);
if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED)))
goto not_this_keyring;
/* Search through the keys in this keyring before its searching its
* subtrees.
*/
if (search_keyring(keyring, ctx))
goto found;
/* Then manually iterate through the keyrings nested in this one.
*
* Start from the root node of the index tree. Because of the way the
* hash function has been set up, keyrings cluster on the leftmost
* branch of the root node (root slot 0) or in the root node itself.
* Non-keyrings avoid the leftmost branch of the root entirely (root
* slots 1-15).
*/
if (!(ctx->flags & KEYRING_SEARCH_RECURSE))
goto not_this_keyring;
ptr = READ_ONCE(keyring->keys.root);
if (!ptr)
goto not_this_keyring;
if (assoc_array_ptr_is_shortcut(ptr)) {
/* If the root is a shortcut, either the keyring only contains
* keyring pointers (everything clusters behind root slot 0) or
* doesn't contain any keyring pointers.
*/
shortcut = assoc_array_ptr_to_shortcut(ptr);
if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
goto not_this_keyring;
ptr = READ_ONCE(shortcut->next_node);
node = assoc_array_ptr_to_node(ptr);
goto begin_node;
}
node = assoc_array_ptr_to_node(ptr);
ptr = node->slots[0];
if (!assoc_array_ptr_is_meta(ptr))
goto begin_node;
descend_to_node:
/* Descend to a more distal node in this keyring's content tree and go
* through that.
*/
kdebug("descend");
if (assoc_array_ptr_is_shortcut(ptr)) {
shortcut = assoc_array_ptr_to_shortcut(ptr);
ptr = READ_ONCE(shortcut->next_node);
BUG_ON(!assoc_array_ptr_is_node(ptr));
}
node = assoc_array_ptr_to_node(ptr);
begin_node:
kdebug("begin_node");
slot = 0;
ascend_to_node:
/* Go through the slots in a node */
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
ptr = READ_ONCE(node->slots[slot]);
if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
goto descend_to_node;
if (!keyring_ptr_is_keyring(ptr))
continue;
key = keyring_ptr_to_key(ptr);
if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
ctx->result = ERR_PTR(-ELOOP);
return false;
}
goto not_this_keyring;
}
/* Search a nested keyring */
if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
key_task_permission(make_key_ref(key, ctx->possessed),
ctx->cred, KEY_NEED_SEARCH) < 0)
continue;
/* stack the current position */
stack[sp].keyring = keyring;
stack[sp].node = node;
stack[sp].slot = slot;
sp++;
/* begin again with the new keyring */
keyring = key;
goto descend_to_keyring;
}
/* We've dealt with all the slots in the current node, so now we need
* to ascend to the parent and continue processing there.
*/
ptr = READ_ONCE(node->back_pointer);
slot = node->parent_slot;
if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
shortcut = assoc_array_ptr_to_shortcut(ptr);
ptr = READ_ONCE(shortcut->back_pointer);
slot = shortcut->parent_slot;
}
if (!ptr)
goto not_this_keyring;
node = assoc_array_ptr_to_node(ptr);
slot++;
/* If we've ascended to the root (zero backpointer), we must have just
* finished processing the leftmost branch rather than the root slots -
* so there can't be any more keyrings for us to find.
*/
if (node->back_pointer) {
kdebug("ascend %d", slot);
goto ascend_to_node;
}
/* The keyring we're looking at was disqualified or didn't contain a
* matching key.
*/
not_this_keyring:
kdebug("not_this_keyring %d", sp);
if (sp <= 0) {
kleave(" = false");
return false;
}
/* Resume the processing of a keyring higher up in the tree */
sp--;
keyring = stack[sp].keyring;
node = stack[sp].node;
slot = stack[sp].slot + 1;
kdebug("ascend to %d [%d]", keyring->serial, slot);
goto ascend_to_node;
/* We found a viable match */
found:
key = key_ref_to_ptr(ctx->result);
key_check(key);
if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
key->last_used_at = ctx->now;
keyring->last_used_at = ctx->now;
while (sp > 0)
stack[--sp].keyring->last_used_at = ctx->now;
}
kleave(" = true");
return true;
}
/**
* 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 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)
{
struct key *keyring;
long err;
ctx->iterator = keyring_search_iterator;
ctx->possessed = is_key_possessed(keyring_ref);
ctx->result = ERR_PTR(-EAGAIN);
keyring = key_ref_to_ptr(keyring_ref);
key_check(keyring);
if (keyring->type != &key_type_keyring)
return ERR_PTR(-ENOTDIR);
if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
if (err < 0)
return ERR_PTR(err);
}
ctx->now = ktime_get_real_seconds();
if (search_nested_keyrings(keyring, ctx))
__key_get(key_ref_to_ptr(ctx->result));
return ctx->result;
}
/**
* 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)
{
struct keyring_search_context ctx = {
.index_key.type = type,
.index_key.description = description,
.index_key.desc_len = strlen(description),
.cred = current_cred(),
.match_data.cmp = key_default_cmp,
.match_data.raw_data = description,
.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
.flags = KEYRING_SEARCH_DO_STATE_CHECK,
};
key_ref_t key;
int ret;
if (recurse)
ctx.flags |= KEYRING_SEARCH_RECURSE;
if (type->match_preparse) {
ret = type->match_preparse(&ctx.match_data);
if (ret < 0)
return ERR_PTR(ret);
}
rcu_read_lock();
key = keyring_search_rcu(keyring, &ctx);
rcu_read_unlock();
if (type->match_free)
type->match_free(&ctx.match_data);
return key;
}
EXPORT_SYMBOL(keyring_search);
static struct key_restriction *keyring_restriction_alloc(
key_restrict_link_func_t check)
{
struct key_restriction *keyres =
kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
if (!keyres)
return ERR_PTR(-ENOMEM);
keyres->check = check;
return keyres;
}
/*
* 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)
{
while (keyres && keyres->key &&
keyres->key->type == &key_type_keyring) {
if (keyres->key == dest_keyring)
return true;
keyres = keyres->key->restrict_link;
}
return false;
}
/**
* 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)
{
struct key *keyring;
struct key_type *restrict_type = NULL;
struct key_restriction *restrict_link;
int ret = 0;
keyring = key_ref_to_ptr(keyring_ref);
key_check(keyring);
if (keyring->type != &key_type_keyring)
return -ENOTDIR;
if (!type) {
restrict_link = keyring_restriction_alloc(restrict_link_reject);
} else {
restrict_type = key_type_lookup(type);
if (IS_ERR(restrict_type))
return PTR_ERR(restrict_type);
if (!restrict_type->lookup_restriction) {
ret = -ENOENT;
goto error;
}
restrict_link = restrict_type->lookup_restriction(restriction);
}
if (IS_ERR(restrict_link)) {
ret = PTR_ERR(restrict_link);
goto error;
}
down_write(&keyring->sem);
down_write(&keyring_serialise_restrict_sem);
if (keyring->restrict_link)
ret = -EEXIST;
else if (keyring_detect_restriction_cycle(keyring, restrict_link))
ret = -EDEADLK;
else
keyring->restrict_link = restrict_link;
up_write(&keyring_serialise_restrict_sem);
up_write(&keyring->sem);
if (ret < 0) {
key_put(restrict_link->key);
kfree(restrict_link);
}
error:
if (restrict_type)
key_type_put(restrict_type);
return ret;
}
EXPORT_SYMBOL(keyring_restrict);
/*
* 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)
{
struct key *keyring, *key;
const void *object;
keyring = key_ref_to_ptr(keyring_ref);
kenter("{%d},{%s,%s}",
keyring->serial, index_key->type->name, index_key->description);
object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
index_key);
if (object)
goto found;
kleave(" = NULL");
return NULL;
found:
key = keyring_ptr_to_key(object);
if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED))) {
kleave(" = NULL [x]");
return NULL;
}
__key_get(key);
kleave(" = {%d}", key->serial);
return make_key_ref(key, is_key_possessed(keyring_ref));
}
/*
* 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)
{
struct user_namespace *ns = current_user_ns();
struct key *keyring;
if (!name)
return ERR_PTR(-EINVAL);
read_lock(&keyring_name_lock);
/* Search this hash bucket for a keyring with a matching name that
* grants Search permission and that hasn't been revoked
*/
list_for_each_entry(keyring, &ns->keyring_name_list, name_link) {
if (!kuid_has_mapping(ns, keyring->user->uid))
continue;
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
continue;
if (strcmp(keyring->description, name) != 0)
continue;
if (uid_keyring) {
if (!test_bit(KEY_FLAG_UID_KEYRING,
&keyring->flags))
continue;
} else {
if (key_permission(make_key_ref(keyring, 0),
KEY_NEED_SEARCH) < 0)
continue;
}
/* we've got a match but we might end up racing with
* key_cleanup() if the keyring is currently 'dead'
* (ie. it has a zero usage count) */
if (!refcount_inc_not_zero(&keyring->usage))
continue;
keyring->last_used_at = ktime_get_real_seconds();
goto out;
}
keyring = ERR_PTR(-ENOKEY);
out:
read_unlock(&keyring_name_lock);
return keyring;
}
static int keyring_detect_cycle_iterator(const void *object,
void *iterator_data)
{
struct keyring_search_context *ctx = iterator_data;
const struct key *key = keyring_ptr_to_key(object);
kenter("{%d}", key->serial);
/* We might get a keyring with matching index-key that is nonetheless a
* different keyring. */
if (key != ctx->match_data.raw_data)
return 0;
ctx->result = ERR_PTR(-EDEADLK);
return 1;
}
/*
* See if a cycle will 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)
{
struct keyring_search_context ctx = {
.index_key = A->index_key,
.match_data.raw_data = A,
.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
.iterator = keyring_detect_cycle_iterator,
.flags = (KEYRING_SEARCH_NO_STATE_CHECK |
KEYRING_SEARCH_NO_UPDATE_TIME |
KEYRING_SEARCH_NO_CHECK_PERM |
KEYRING_SEARCH_DETECT_TOO_DEEP |
KEYRING_SEARCH_RECURSE),
};
rcu_read_lock();
search_nested_keyrings(B, &ctx);
rcu_read_unlock();
return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
}
/*
* 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)
{
if (keyring->type != &key_type_keyring)
return -ENOTDIR;
down_write(&keyring->sem);
/* Serialise link/link calls to prevent parallel calls causing a cycle
* when linking two keyring in opposite orders.
*/
if (index_key->type == &key_type_keyring)
mutex_lock(&keyring_serialise_link_lock);
return 0;
}
/*
* 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)
{
if (l_keyring->type != &key_type_keyring ||
u_keyring->type != &key_type_keyring)
return -ENOTDIR;
/* We have to be very careful here to take the keyring locks in the
* right order, lest we open ourselves to deadlocking against another
* move operation.
*/
if (l_keyring < u_keyring) {
down_write(&l_keyring->sem);
down_write_nested(&u_keyring->sem, 1);
} else {
down_write(&u_keyring->sem);
down_write_nested(&l_keyring->sem, 1);
}
/* Serialise link/link calls to prevent parallel calls causing a cycle
* when linking two keyring in opposite orders.
*/
if (index_key->type == &key_type_keyring)
mutex_lock(&keyring_serialise_link_lock);
return 0;
}
/*
* 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)
{
struct assoc_array_edit *edit;
int ret;
kenter("%d,%s,%s,",
keyring->serial, index_key->type->name, index_key->description);
BUG_ON(index_key->desc_len == 0);
BUG_ON(*_edit != NULL);
*_edit = NULL;
ret = -EKEYREVOKED;
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
goto error;
/* Create an edit script that will insert/replace the key in the
* keyring tree.
*/
edit = assoc_array_insert(&keyring->keys,
&keyring_assoc_array_ops,
index_key,
NULL);
if (IS_ERR(edit)) {
ret = PTR_ERR(edit);
goto error;
}
/* If we're not replacing a link in-place then we're going to need some
* extra quota.
*/
if (!edit->dead_leaf) {
ret = key_payload_reserve(keyring,
keyring->datalen + KEYQUOTA_LINK_BYTES);
if (ret < 0)
goto error_cancel;
}
*_edit = edit;
kleave(" = 0");
return 0;
error_cancel:
assoc_array_cancel_edit(edit);
error:
kleave(" = %d", ret);
return ret;
}
/*
* 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)
{
if (key->type == &key_type_keyring)
/* check that we aren't going to create a cycle by linking one
* keyring to another */
return keyring_detect_cycle(keyring, key);
return 0;
}
/*
* 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 *key, struct assoc_array_edit **_edit)
{
__key_get(key);
assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
assoc_array_apply_edit(*_edit);
*_edit = NULL;
}
/*
* 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)
{
BUG_ON(index_key->type == NULL);
kenter("%d,%s,", keyring->serial, index_key->type->name);
if (edit) {
if (!edit->dead_leaf) {
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
}
assoc_array_cancel_edit(edit);
}
up_write(&keyring->sem);
if (index_key->type == &key_type_keyring)
mutex_unlock(&keyring_serialise_link_lock);
}
/*
* Check addition of keys to restricted keyrings.
*/
static int __key_link_check_restriction(struct key *keyring, struct key *key)
{
if (!keyring->restrict_link || !keyring->restrict_link->check)
return 0;
return keyring->restrict_link->check(keyring, key->type, &key->payload,
keyring->restrict_link->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)
{
struct assoc_array_edit *edit = NULL;
int ret;
kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
key_check(keyring);
key_check(key);
ret = __key_link_lock(keyring, &key->index_key);
if (ret < 0)
goto error;
ret = __key_link_begin(keyring, &key->index_key, &edit);
if (ret < 0)
goto error_end;
kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
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);
error_end:
__key_link_end(keyring, &key->index_key, edit);
error:
kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
return ret;
}
EXPORT_SYMBOL(key_link);
/*
* Lock a keyring for unlink.
*/
static int __key_unlink_lock(struct key *keyring)
__acquires(&keyring->sem)
{
if (keyring->type != &key_type_keyring)
return -ENOTDIR;
down_write(&keyring->sem);
return 0;
}
/*
* 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)
{
struct assoc_array_edit *edit;
BUG_ON(*_edit != NULL);
edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
&key->index_key);
if (IS_ERR(edit))
return PTR_ERR(edit);
if (!edit)
return -ENOENT;
*_edit = edit;
return 0;
}
/*
* Apply an unlink change.
*/
static void __key_unlink(struct key *keyring, struct key *key,
struct assoc_array_edit **_edit)
{
assoc_array_apply_edit(*_edit);
*_edit = NULL;
key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
}
/*
* 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)
{
if (edit)
assoc_array_cancel_edit(edit);
up_write(&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)
{
struct assoc_array_edit *edit = NULL;
int ret;
key_check(keyring);
key_check(key);
ret = __key_unlink_lock(keyring);
if (ret < 0)
return ret;
ret = __key_unlink_begin(keyring, key, &edit);
if (ret == 0)
__key_unlink(keyring, key, &edit);
__key_unlink_end(keyring, key, edit);
return ret;
}
EXPORT_SYMBOL(key_unlink);
/**
* 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)
{
struct assoc_array_edit *from_edit = NULL, *to_edit = NULL;
int ret;
kenter("%d,%d,%d", key->serial, from_keyring->serial, to_keyring->serial);
if (from_keyring == to_keyring)
return 0;
key_check(key);
key_check(from_keyring);
key_check(to_keyring);
ret = __key_move_lock(from_keyring, to_keyring, &key->index_key);
if (ret < 0)
goto out;
ret = __key_unlink_begin(from_keyring, key, &from_edit);
if (ret < 0)
goto error;
ret = __key_link_begin(to_keyring, &key->index_key, &to_edit);
if (ret < 0)
goto error;
ret = -EEXIST;
if (to_edit->dead_leaf && (flags & KEYCTL_MOVE_EXCL))
goto error;
ret = __key_link_check_restriction(to_keyring, key);
if (ret < 0)
goto error;
ret = __key_link_check_live_key(to_keyring, key);
if (ret < 0)
goto error;
__key_unlink(from_keyring, key, &from_edit);
__key_link(key, &to_edit);
error:
__key_link_end(to_keyring, &key->index_key, to_edit);
__key_unlink_end(from_keyring, key, from_edit);
out:
kleave(" = %d", ret);
return ret;
}
EXPORT_SYMBOL(key_move);
/**
* 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)
{
struct assoc_array_edit *edit;
int ret;
if (keyring->type != &key_type_keyring)
return -ENOTDIR;
down_write(&keyring->sem);
edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
if (IS_ERR(edit)) {
ret = PTR_ERR(edit);
} else {
if (edit)
assoc_array_apply_edit(edit);
key_payload_reserve(keyring, 0);
ret = 0;
}
up_write(&keyring->sem);
return ret;
}
EXPORT_SYMBOL(keyring_clear);
/*
* Dispose of the links from a revoked keyring.
*
* This is called with the key sem write-locked.
*/
static void keyring_revoke(struct key *keyring)
{
struct assoc_array_edit *edit;
edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
if (!IS_ERR(edit)) {
if (edit)
assoc_array_apply_edit(edit);
key_payload_reserve(keyring, 0);
}
}
static bool keyring_gc_select_iterator(void *object, void *iterator_data)
{
struct key *key = keyring_ptr_to_key(object);
time64_t *limit = iterator_data;
if (key_is_dead(key, *limit))
return false;
key_get(key);
return true;
}
static int keyring_gc_check_iterator(const void *object, void *iterator_data)
{
const struct key *key = keyring_ptr_to_key(object);
time64_t *limit = iterator_data;
key_check(key);
return key_is_dead(key, *limit);
}
/*
* 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)
{
int result;
kenter("%x{%s}", keyring->serial, keyring->description ?: "");
if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED)))
goto dont_gc;
/* scan the keyring looking for dead keys */
rcu_read_lock();
result = assoc_array_iterate(&keyring->keys,
keyring_gc_check_iterator, &limit);
rcu_read_unlock();
if (result == true)
goto do_gc;
dont_gc:
kleave(" [no gc]");
return;
do_gc:
down_write(&keyring->sem);
assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
keyring_gc_select_iterator, &limit);
up_write(&keyring->sem);
kleave(" [gc]");
}
/*
* 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)
{
struct key_restriction *keyres;
kenter("%x{%s}", keyring->serial, keyring->description ?: "");
/*
* keyring->restrict_link is only assigned at key allocation time
* or with the key type locked, so the only values that could be
* concurrently assigned to keyring->restrict_link are for key
* types other than dead_type. Given this, it's ok to check
* the key type before acquiring keyring->sem.
*/
if (!dead_type || !keyring->restrict_link ||
keyring->restrict_link->keytype != dead_type) {
kleave(" [no restriction gc]");
return;
}
/* Lock the keyring to ensure that a link is not in progress */
down_write(&keyring->sem);
keyres = keyring->restrict_link;
keyres->check = restrict_link_reject;
key_put(keyres->key);
keyres->key = NULL;
keyres->keytype = NULL;
up_write(&keyring->sem);
kleave(" [restriction gc]");
}