/* Keyring handling
*
* Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/module.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 <keys/keyring-type.h>
#include <keys/user-type.h>
#include <linux/assoc_array_priv.h>
#include <linux/uaccess.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 keep all named keyrings in a hash to speed looking them up.
*/
#define KEYRING_NAME_HASH_SIZE (1 << 5)
/*
* 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 struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
static DEFINE_RWLOCK(keyring_name_lock);
static inline unsigned keyring_hash(const char *desc)
{
unsigned bucket = 0;
for (; *desc; desc++)
bucket += (unsigned char)*desc;
return bucket & (KEYRING_NAME_HASH_SIZE - 1);
}
/*
* 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 DECLARE_RWSEM(keyring_serialise_link_sem);
/*
* Publish the name of a keyring so that it can be found by name (if it has
* one).
*/
static void keyring_publish_name(struct key *keyring)
{
int bucket;
if (keyring->description) {
bucket = keyring_hash(keyring->description);
write_lock(&keyring_name_lock);
if (!keyring_name_hash[bucket].next)
INIT_LIST_HEAD(&keyring_name_hash[bucket]);
list_add_tail(&keyring->name_link,
&keyring_name_hash[bucket]);
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 unsigned long hash_key_type_and_desc(const 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);
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)
return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
return (hash + (hash << level_shift)) & ~fan_mask;
return hash;
}
/*
* Build the next index key chunk.
*
* On 32-bit systems the index key is laid out as:
*
* 0 4 5 9...
* hash desclen typeptr desc[]
*
* On 64-bit systems:
*
* 0 8 9 17...
* hash desclen typeptr desc[]
*
* 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;
long offset = 0;
int desc_len = index_key->desc_len, n = sizeof(chunk);
level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
switch (level) {
case 0:
return hash_key_type_and_desc(index_key);
case 1:
return ((unsigned long)index_key->type << 8) | desc_len;
case 2:
if (desc_len == 0)
return (u8)((unsigned long)index_key->type >>
(ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
n--;
offset = 1;
default:
offset += sizeof(chunk) - 1;
offset += (level - 3) * sizeof(chunk);
if (offset >= desc_len)
return 0;
desc_len -= offset;
if (desc_len > n)
desc_len = n;
offset += desc_len;
do {
chunk <<= 8;
chunk |= ((u8*)index_key->description)[--offset];
} while (--desc_len > 0);
if (level == 2) {
chunk <<= 8;
chunk |= (u8)((unsigned long)index_key->type >>
(ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
}
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.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 = hash_key_type_and_desc(a);
seg_b = hash_key_type_and_desc(b);
if ((seg_a ^ seg_b) != 0)
goto differ;
/* 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.
*/
level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
seg_a = a->desc_len;
seg_b = b->desc_len;
if ((seg_a ^ seg_b) != 0)
goto differ;
/* The next bit may not work on big endian */
level++;
seg_a = (unsigned long)a->type;
seg_b = (unsigned long)b->type;
if ((seg_a ^ seg_b) != 0)
goto differ;
level += sizeof(unsigned long);
if (a->desc_len == 0)
goto same;
i = 0;
if (((unsigned long)a->description | (unsigned long)b->description) &
(sizeof(unsigned long) - 1)) {
do {
seg_a = *(unsigned long *)(a->description + i);
seg_b = *(unsigned long *)(b->description + i);
if ((seg_a ^ seg_b) != 0)
goto differ_plus_i;
i += sizeof(unsigned long);
} while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
}
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);
}
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_instantiated(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 qty;
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->qty);
if (ctx->count >= ctx->qty)
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;
unsigned long nr_keys;
int ret;
kenter("{%d},,%zu", key_serial(keyring), buflen);
if (buflen & (sizeof(key_serial_t) - 1))
return -EINVAL;
nr_keys = keyring->keys.nr_leaves_on_tree;
if (nr_keys == 0)
return 0;
/* Calculate how much data we could return */
ctx.qty = nr_keys * sizeof(key_serial_t);
if (!buffer || !buflen)
return ctx.qty;
if (buflen > ctx.qty)
ctx.qty = buflen;
/* Copy the IDs of the subscribed keys into the buffer */
ctx.buffer = (key_serial_t __user *)buffer;
ctx.count = 0;
ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
if (ret < 0) {
kleave(" = %d [iterate]", ret);
return ret;
}
kleave(" = %zu [ok]", ctx.count);
return ctx.count;
}
/*
* 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 *dest)
{
struct key *keyring;
int ret;
keyring = key_alloc(&key_type_keyring, description,
uid, gid, cred, perm, flags);
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);
/*
* 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 = key->flags;
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) {
if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED))) {
ctx->result = ERR_PTR(-EKEYREVOKED);
kleave(" = %d [invrev]", ctx->skipped_ret);
goto skipped;
}
if (key->expiry && ctx->now.tv_sec >= key->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 (kflags & (1 << KEY_FLAG_NEGATIVE)) {
smp_rmb();
ctx->result = ERR_PTR(key->reject_error);
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)
ctx->index_key.desc_len = strlen(ctx->index_key.description);
/* 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).
*/
ptr = ACCESS_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);
smp_read_barrier_depends();
if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
goto not_this_keyring;
ptr = ACCESS_ONCE(shortcut->next_node);
node = assoc_array_ptr_to_node(ptr);
goto begin_node;
}
node = assoc_array_ptr_to_node(ptr);
smp_read_barrier_depends();
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);
smp_read_barrier_depends();
ptr = ACCESS_ONCE(shortcut->next_node);
BUG_ON(!assoc_array_ptr_is_node(ptr));
}
node = assoc_array_ptr_to_node(ptr);
begin_node:
kdebug("begin_node");
smp_read_barrier_depends();
slot = 0;
ascend_to_node:
/* Go through the slots in a node */
for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
ptr = ACCESS_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 = ACCESS_ONCE(node->back_pointer);
slot = node->parent_slot;
if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
shortcut = assoc_array_ptr_to_shortcut(ptr);
smp_read_barrier_depends();
ptr = ACCESS_ONCE(shortcut->back_pointer);
slot = shortcut->parent_slot;
}
if (!ptr)
goto not_this_keyring;
node = assoc_array_ptr_to_node(ptr);
smp_read_barrier_depends();
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.tv_sec;
keyring->last_used_at = ctx->now.tv_sec;
while (sp > 0)
stack[--sp].keyring->last_used_at = ctx->now.tv_sec;
}
kleave(" = true");
return true;
}
/**
* keyring_search_aux - Search a keyring tree for a key matching some criteria
* @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).
*
* 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_aux(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);
}
rcu_read_lock();
ctx->now = current_kernel_time();
if (search_nested_keyrings(keyring, ctx))
__key_get(key_ref_to_ptr(ctx->result));
rcu_read_unlock();
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.
*
* As keyring_search_aux() 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)
{
struct keyring_search_context ctx = {
.index_key.type = type,
.index_key.description = 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 (type->match_preparse) {
ret = type->match_preparse(&ctx.match_data);
if (ret < 0)
return ERR_PTR(ret);
}
key = keyring_search_aux(keyring, &ctx);
if (type->match_free)
type->match_free(&ctx.match_data);
return key;
}
EXPORT_SYMBOL(keyring_search);
/*
* 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.
*
* All named keyrings in the current user namespace are searched, provided they
* grant Search permission directly to the caller (unless this check is
* skipped). Keyrings whose usage points have reached zero or who have been
* revoked are skipped.
*
* 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 skip_perm_check)
{
struct key *keyring;
int bucket;
if (!name)
return ERR_PTR(-EINVAL);
bucket = keyring_hash(name);
read_lock(&keyring_name_lock);
if (keyring_name_hash[bucket].next) {
/* search this hash bucket for a keyring with a matching name
* that's readable and that hasn't been revoked */
list_for_each_entry(keyring,
&keyring_name_hash[bucket],
name_link
) {
if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
continue;
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
continue;
if (strcmp(keyring->description, name) != 0)
continue;
if (!skip_perm_check &&
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 (!atomic_inc_not_zero(&keyring->usage))
continue;
keyring->last_used_at = current_kernel_time().tv_sec;
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),
};
rcu_read_lock();
search_nested_keyrings(B, &ctx);
rcu_read_unlock();
return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
}
/*
* 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)
__acquires(&keyring->sem)
__acquires(&keyring_serialise_link_sem)
{
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);
if (keyring->type != &key_type_keyring)
return -ENOTDIR;
down_write(&keyring->sem);
ret = -EKEYREVOKED;
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
goto error_krsem;
/* 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)
down_write(&keyring_serialise_link_sem);
/* 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_sem;
}
/* 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_sem:
if (index_key->type == &key_type_keyring)
up_write(&keyring_serialise_link_sem);
error_krsem:
up_write(&keyring->sem);
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_sem)
{
BUG_ON(index_key->type == NULL);
kenter("%d,%s,", keyring->serial, index_key->type->name);
if (index_key->type == &key_type_keyring)
up_write(&keyring_serialise_link_sem);
if (edit) {
if (!edit->dead_leaf) {
key_payload_reserve(keyring,
keyring->datalen - KEYQUOTA_LINK_BYTES);
}
assoc_array_cancel_edit(edit);
}
up_write(&keyring->sem);
}
/**
* 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;
int ret;
kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage));
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);
if (ret == 0)
__key_link(key, &edit);
__key_link_end(keyring, &key->index_key, edit);
}
kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage));
return ret;
}
EXPORT_SYMBOL(key_link);
/**
* 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;
int ret;
key_check(keyring);
key_check(key);
if (keyring->type != &key_type_keyring)
return -ENOTDIR;
down_write(&keyring->sem);
edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
&key->index_key);
if (IS_ERR(edit)) {
ret = PTR_ERR(edit);
goto error;
}
ret = -ENOENT;
if (edit == NULL)
goto error;
assoc_array_apply_edit(edit);
key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
ret = 0;
error:
up_write(&keyring->sem);
return ret;
}
EXPORT_SYMBOL(key_unlink);
/**
* 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);
time_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);
time_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, time_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]");
}