--- /dev/null
+/* keyring.c: keyring handling
+ *
+ * Copyright (C) 2004 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/seq_file.h>
+#include <linux/err.h>
+#include <asm/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)
+
+static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
+static rwlock_t keyring_name_lock = RW_LOCK_UNLOCKED;
+
+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 type definition
+ */
+static int keyring_instantiate(struct key *keyring,
+ const void *data, size_t datalen);
+static int keyring_duplicate(struct key *keyring, const struct key *source);
+static int keyring_match(const struct key *keyring, const void *criterion);
+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 = sizeof(struct keyring_list),
+ .instantiate = keyring_instantiate,
+ .duplicate = keyring_duplicate,
+ .match = keyring_match,
+ .destroy = keyring_destroy,
+ .describe = keyring_describe,
+ .read = keyring_read,
+};
+
+/*
+ * semaphore to serialise link/link calls to prevent two link calls in parallel
+ * introducing a cycle
+ */
+DECLARE_RWSEM(keyring_serialise_link_sem);
+
+/*****************************************************************************/
+/*
+ * publish the name of a keyring so that it can be found by name (if it has
+ * one)
+ */
+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->type_data.link,
+ &keyring_name_hash[bucket]);
+
+ write_unlock(&keyring_name_lock);
+ }
+
+} /* end keyring_publish_name() */
+
+/*****************************************************************************/
+/*
+ * initialise a keyring
+ * - we object if we were given any data
+ */
+static int keyring_instantiate(struct key *keyring,
+ const void *data, size_t datalen)
+{
+ int ret;
+
+ ret = -EINVAL;
+ if (datalen == 0) {
+ /* make the keyring available by name if it has one */
+ keyring_publish_name(keyring);
+ ret = 0;
+ }
+
+ return ret;
+
+} /* end keyring_instantiate() */
+
+/*****************************************************************************/
+/*
+ * duplicate the list of subscribed keys from a source keyring into this one
+ */
+static int keyring_duplicate(struct key *keyring, const struct key *source)
+{
+ struct keyring_list *sklist, *klist;
+ unsigned max;
+ size_t size;
+ int loop, ret;
+
+ const unsigned limit =
+ (PAGE_SIZE - sizeof(*klist)) / sizeof(struct key);
+
+ ret = 0;
+ sklist = source->payload.subscriptions;
+
+ if (sklist && sklist->nkeys > 0) {
+ max = sklist->nkeys;
+ BUG_ON(max > limit);
+
+ max = (max + 3) & ~3;
+ if (max > limit)
+ max = limit;
+
+ ret = -ENOMEM;
+ size = sizeof(*klist) + sizeof(struct key) * max;
+ klist = kmalloc(size, GFP_KERNEL);
+ if (!klist)
+ goto error;
+
+ klist->maxkeys = max;
+ klist->nkeys = sklist->nkeys;
+ memcpy(klist->keys,
+ sklist->keys,
+ sklist->nkeys * sizeof(struct key));
+
+ for (loop = klist->nkeys - 1; loop >= 0; loop--)
+ atomic_inc(&klist->keys[loop]->usage);
+
+ keyring->payload.subscriptions = klist;
+ ret = 0;
+ }
+
+ error:
+ return ret;
+
+} /* end keyring_duplicate() */
+
+/*****************************************************************************/
+/*
+ * match keyrings on their name
+ */
+static int keyring_match(const struct key *keyring, const void *description)
+{
+ return keyring->description &&
+ strcmp(keyring->description, description) == 0;
+
+} /* end keyring_match() */
+
+/*****************************************************************************/
+/*
+ * dispose of the data dangling from the corpse of a keyring
+ */
+static void keyring_destroy(struct key *keyring)
+{
+ struct keyring_list *klist;
+ int loop;
+
+ if (keyring->description) {
+ write_lock(&keyring_name_lock);
+ list_del(&keyring->type_data.link);
+ write_unlock(&keyring_name_lock);
+ }
+
+ klist = keyring->payload.subscriptions;
+ if (klist) {
+ for (loop = klist->nkeys - 1; loop >= 0; loop--)
+ key_put(klist->keys[loop]);
+ kfree(klist);
+ }
+
+} /* end keyring_destroy() */
+
+/*****************************************************************************/
+/*
+ * describe the keyring
+ */
+static void keyring_describe(const struct key *keyring, struct seq_file *m)
+{
+ struct keyring_list *klist;
+
+ if (keyring->description) {
+ seq_puts(m, keyring->description);
+ }
+ else {
+ seq_puts(m, "[anon]");
+ }
+
+ klist = keyring->payload.subscriptions;
+ if (klist)
+ seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
+ else
+ seq_puts(m, ": empty");
+
+} /* end keyring_describe() */
+
+/*****************************************************************************/
+/*
+ * read a list of key IDs from the keyring's contents
+ */
+static long keyring_read(const struct key *keyring,
+ char __user *buffer, size_t buflen)
+{
+ struct keyring_list *klist;
+ struct key *key;
+ size_t qty, tmp;
+ int loop, ret;
+
+ ret = 0;
+ klist = keyring->payload.subscriptions;
+
+ if (klist) {
+ /* calculate how much data we could return */
+ qty = klist->nkeys * sizeof(key_serial_t);
+
+ if (buffer && buflen > 0) {
+ if (buflen > qty)
+ buflen = qty;
+
+ /* copy the IDs of the subscribed keys into the
+ * buffer */
+ ret = -EFAULT;
+
+ for (loop = 0; loop < klist->nkeys; loop++) {
+ key = klist->keys[loop];
+
+ tmp = sizeof(key_serial_t);
+ if (tmp > buflen)
+ tmp = buflen;
+
+ if (copy_to_user(buffer,
+ &key->serial,
+ tmp) != 0)
+ goto error;
+
+ buflen -= tmp;
+ if (buflen == 0)
+ break;
+ buffer += tmp;
+ }
+ }
+
+ ret = qty;
+ }
+
+ error:
+ return ret;
+
+} /* end keyring_read() */
+
+/*****************************************************************************/
+/*
+ * allocate a keyring and link into the destination keyring
+ */
+struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
+ int not_in_quota, struct key *dest)
+{
+ struct key *keyring;
+ int ret;
+
+ keyring = key_alloc(&key_type_keyring, description,
+ uid, gid, KEY_USR_ALL, not_in_quota);
+
+ if (!IS_ERR(keyring)) {
+ ret = key_instantiate_and_link(keyring, NULL, 0, dest);
+ if (ret < 0) {
+ key_put(keyring);
+ keyring = ERR_PTR(ret);
+ }
+ }
+
+ return keyring;
+
+} /* end keyring_alloc() */
+
+/*****************************************************************************/
+/*
+ * search the supplied keyring tree for a key that matches the criterion
+ * - perform a breadth-then-depth search up to the prescribed limit
+ * - we only find keys on which we have search permission
+ * - we use the supplied match function to see if the description (or other
+ * feature of interest) matches
+ * - we readlock the keyrings as we search down the tree
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we only found negative matching keys
+ */
+struct key *keyring_search_aux(struct key *keyring,
+ struct key_type *type,
+ const void *description,
+ key_match_func_t match)
+{
+ struct {
+ struct key *keyring;
+ int kix;
+ } stack[KEYRING_SEARCH_MAX_DEPTH];
+
+ struct keyring_list *keylist;
+ struct timespec now;
+ struct key *key;
+ long err;
+ int sp, psp, kix;
+
+ key_check(keyring);
+
+ /* top keyring must have search permission to begin the search */
+ key = ERR_PTR(-EACCES);
+ if (!key_permission(keyring, KEY_SEARCH))
+ goto error;
+
+ key = ERR_PTR(-ENOTDIR);
+ if (keyring->type != &key_type_keyring)
+ goto error;
+
+ now = current_kernel_time();
+ err = -EAGAIN;
+ sp = 0;
+
+ /* start processing a new keyring */
+ descend:
+ read_lock(&keyring->lock);
+ if (keyring->flags & KEY_FLAG_REVOKED)
+ goto not_this_keyring;
+
+ keylist = keyring->payload.subscriptions;
+ if (!keylist)
+ goto not_this_keyring;
+
+ /* iterate through the keys in this keyring first */
+ for (kix = 0; kix < keylist->nkeys; kix++) {
+ key = keylist->keys[kix];
+
+ /* ignore keys not of this type */
+ if (key->type != type)
+ continue;
+
+ /* skip revoked keys and expired keys */
+ if (key->flags & KEY_FLAG_REVOKED)
+ continue;
+
+ if (key->expiry && now.tv_sec >= key->expiry)
+ continue;
+
+ /* keys that don't match */
+ if (!match(key, description))
+ continue;
+
+ /* key must have search permissions */
+ if (!key_permission(key, KEY_SEARCH))
+ continue;
+
+ /* we set a different error code if we find a negative key */
+ if (key->flags & KEY_FLAG_NEGATIVE) {
+ err = -ENOKEY;
+ continue;
+ }
+
+ goto found;
+ }
+
+ /* search through the keyrings nested in this one */
+ kix = 0;
+ ascend:
+ while (kix < keylist->nkeys) {
+ key = keylist->keys[kix];
+ if (key->type != &key_type_keyring)
+ goto next;
+
+ /* recursively search nested keyrings
+ * - only search keyrings for which we have search permission
+ */
+ if (sp >= KEYRING_SEARCH_MAX_DEPTH)
+ goto next;
+
+ if (!key_permission(key, KEY_SEARCH))
+ goto next;
+
+ /* evade loops in the keyring tree */
+ for (psp = 0; psp < sp; psp++)
+ if (stack[psp].keyring == keyring)
+ goto next;
+
+ /* stack the current position */
+ stack[sp].keyring = keyring;
+ stack[sp].kix = kix;
+ sp++;
+
+ /* begin again with the new keyring */
+ keyring = key;
+ goto descend;
+
+ next:
+ kix++;
+ }
+
+ /* the keyring we're looking at was disqualified or didn't contain a
+ * matching key */
+ not_this_keyring:
+ read_unlock(&keyring->lock);
+
+ if (sp > 0) {
+ /* resume the processing of a keyring higher up in the tree */
+ sp--;
+ keyring = stack[sp].keyring;
+ keylist = keyring->payload.subscriptions;
+ kix = stack[sp].kix + 1;
+ goto ascend;
+ }
+
+ key = ERR_PTR(err);
+ goto error;
+
+ /* we found a viable match */
+ found:
+ atomic_inc(&key->usage);
+ read_unlock(&keyring->lock);
+
+ /* unwind the keyring stack */
+ while (sp > 0) {
+ sp--;
+ read_unlock(&stack[sp].keyring->lock);
+ }
+
+ key_check(key);
+ error:
+ return key;
+
+} /* end keyring_search_aux() */
+
+/*****************************************************************************/
+/*
+ * search the supplied keyring tree for a key that matches the criterion
+ * - perform a breadth-then-depth search up to the prescribed limit
+ * - we only find keys on which we have search permission
+ * - we readlock the keyrings as we search down the tree
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we only found negative matching keys
+ */
+struct key *keyring_search(struct key *keyring,
+ struct key_type *type,
+ const char *description)
+{
+ return keyring_search_aux(keyring, type, description, type->match);
+
+} /* end keyring_search() */
+
+EXPORT_SYMBOL(keyring_search);
+
+/*****************************************************************************/
+/*
+ * search the given keyring only (no recursion)
+ * - keyring must be locked by caller
+ */
+struct key *__keyring_search_one(struct key *keyring,
+ const struct key_type *ktype,
+ const char *description,
+ key_perm_t perm)
+{
+ struct keyring_list *klist;
+ struct key *key;
+ int loop;
+
+ klist = keyring->payload.subscriptions;
+ if (klist) {
+ for (loop = 0; loop < klist->nkeys; loop++) {
+ key = klist->keys[loop];
+
+ if (key->type == ktype &&
+ key->type->match(key, description) &&
+ key_permission(key, perm) &&
+ !(key->flags & KEY_FLAG_REVOKED)
+ )
+ goto found;
+ }
+ }
+
+ key = ERR_PTR(-ENOKEY);
+ goto error;
+
+ found:
+ atomic_inc(&key->usage);
+ error:
+ return key;
+
+} /* end __keyring_search_one() */
+
+/*****************************************************************************/
+/*
+ * find a keyring with the specified name
+ * - all named keyrings are searched
+ * - only find keyrings with search permission for the process
+ * - only find keyrings with a serial number greater than the one specified
+ */
+struct key *find_keyring_by_name(const char *name, key_serial_t bound)
+{
+ struct key *keyring;
+ int bucket;
+
+ keyring = ERR_PTR(-EINVAL);
+ if (!name)
+ goto error;
+
+ 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],
+ type_data.link
+ ) {
+ if (keyring->flags & KEY_FLAG_REVOKED)
+ continue;
+
+ if (strcmp(keyring->description, name) != 0)
+ continue;
+
+ if (!key_permission(keyring, KEY_SEARCH))
+ continue;
+
+ /* found a potential candidate, but we still need to
+ * check the serial number */
+ if (keyring->serial <= bound)
+ continue;
+
+ /* we've got a match */
+ atomic_inc(&keyring->usage);
+ read_unlock(&keyring_name_lock);
+ goto error;
+ }
+ }
+
+ read_unlock(&keyring_name_lock);
+ keyring = ERR_PTR(-ENOKEY);
+
+ error:
+ return keyring;
+
+} /* end find_keyring_by_name() */
+
+/*****************************************************************************/
+/*
+ * 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 {
+ struct key *subtree;
+ int kix;
+ } stack[KEYRING_SEARCH_MAX_DEPTH];
+
+ struct keyring_list *keylist;
+ struct key *subtree, *key;
+ int sp, kix, ret;
+
+ ret = -EDEADLK;
+ if (A == B)
+ goto error;
+
+ subtree = B;
+ sp = 0;
+
+ /* start processing a new keyring */
+ descend:
+ read_lock(&subtree->lock);
+ if (subtree->flags & KEY_FLAG_REVOKED)
+ goto not_this_keyring;
+
+ keylist = subtree->payload.subscriptions;
+ if (!keylist)
+ goto not_this_keyring;
+ kix = 0;
+
+ ascend:
+ /* iterate through the remaining keys in this keyring */
+ for (; kix < keylist->nkeys; kix++) {
+ key = keylist->keys[kix];
+
+ if (key == A)
+ goto cycle_detected;
+
+ /* recursively check nested keyrings */
+ if (key->type == &key_type_keyring) {
+ if (sp >= KEYRING_SEARCH_MAX_DEPTH)
+ goto too_deep;
+
+ /* stack the current position */
+ stack[sp].subtree = subtree;
+ stack[sp].kix = kix;
+ sp++;
+
+ /* begin again with the new keyring */
+ subtree = key;
+ goto descend;
+ }
+ }
+
+ /* the keyring we're looking at was disqualified or didn't contain a
+ * matching key */
+ not_this_keyring:
+ read_unlock(&subtree->lock);
+
+ if (sp > 0) {
+ /* resume the checking of a keyring higher up in the tree */
+ sp--;
+ subtree = stack[sp].subtree;
+ keylist = subtree->payload.subscriptions;
+ kix = stack[sp].kix + 1;
+ goto ascend;
+ }
+
+ ret = 0; /* no cycles detected */
+
+ error:
+ return ret;
+
+ too_deep:
+ ret = -ELOOP;
+ goto error_unwind;
+ cycle_detected:
+ ret = -EDEADLK;
+ error_unwind:
+ read_unlock(&subtree->lock);
+
+ /* unwind the keyring stack */
+ while (sp > 0) {
+ sp--;
+ read_unlock(&stack[sp].subtree->lock);
+ }
+
+ goto error;
+
+} /* end keyring_detect_cycle() */
+
+/*****************************************************************************/
+/*
+ * link a key into to a keyring
+ * - must be called with the keyring's semaphore held
+ */
+int __key_link(struct key *keyring, struct key *key)
+{
+ struct keyring_list *klist, *nklist;
+ unsigned max;
+ size_t size;
+ int ret;
+
+ ret = -EKEYREVOKED;
+ if (keyring->flags & KEY_FLAG_REVOKED)
+ goto error;
+
+ ret = -ENOTDIR;
+ if (keyring->type != &key_type_keyring)
+ goto error;
+
+ /* serialise link/link calls to prevent parallel calls causing a
+ * cycle when applied to two keyring in opposite orders */
+ down_write(&keyring_serialise_link_sem);
+
+ /* check that we aren't going to create a cycle adding one keyring to
+ * another */
+ if (key->type == &key_type_keyring) {
+ ret = keyring_detect_cycle(keyring, key);
+ if (ret < 0)
+ goto error2;
+ }
+
+ /* check that we aren't going to overrun the user's quota */
+ ret = key_payload_reserve(keyring,
+ keyring->datalen + KEYQUOTA_LINK_BYTES);
+ if (ret < 0)
+ goto error2;
+
+ klist = keyring->payload.subscriptions;
+
+ if (klist && klist->nkeys < klist->maxkeys) {
+ /* there's sufficient slack space to add directly */
+ atomic_inc(&key->usage);
+
+ write_lock(&keyring->lock);
+ klist->keys[klist->nkeys++] = key;
+ write_unlock(&keyring->lock);
+
+ ret = 0;
+ }
+ else {
+ /* grow the key list */
+ max = 4;
+ if (klist)
+ max += klist->maxkeys;
+
+ ret = -ENFILE;
+ size = sizeof(*klist) + sizeof(*key) * max;
+ if (size > PAGE_SIZE)
+ goto error3;
+
+ ret = -ENOMEM;
+ nklist = kmalloc(size, GFP_KERNEL);
+ if (!nklist)
+ goto error3;
+ nklist->maxkeys = max;
+ nklist->nkeys = 0;
+
+ if (klist) {
+ nklist->nkeys = klist->nkeys;
+ memcpy(nklist->keys,
+ klist->keys,
+ sizeof(struct key *) * klist->nkeys);
+ }
+
+ /* add the key into the new space */
+ atomic_inc(&key->usage);
+
+ write_lock(&keyring->lock);
+ keyring->payload.subscriptions = nklist;
+ nklist->keys[nklist->nkeys++] = key;
+ write_unlock(&keyring->lock);
+
+ /* dispose of the old keyring list */
+ kfree(klist);
+
+ ret = 0;
+ }
+
+ error2:
+ up_write(&keyring_serialise_link_sem);
+ error:
+ return ret;
+
+ error3:
+ /* undo the quota changes */
+ key_payload_reserve(keyring,
+ keyring->datalen - KEYQUOTA_LINK_BYTES);
+ goto error2;
+
+} /* end __key_link() */
+
+/*****************************************************************************/
+/*
+ * link a key to a keyring
+ */
+int key_link(struct key *keyring, struct key *key)
+{
+ int ret;
+
+ key_check(keyring);
+ key_check(key);
+
+ down_write(&keyring->sem);
+ ret = __key_link(keyring, key);
+ up_write(&keyring->sem);
+
+ return ret;
+
+} /* end key_link() */
+
+EXPORT_SYMBOL(key_link);
+
+/*****************************************************************************/
+/*
+ * unlink the first link to a key from a keyring
+ */
+int key_unlink(struct key *keyring, struct key *key)
+{
+ struct keyring_list *klist;
+ int loop, ret;
+
+ key_check(keyring);
+ key_check(key);
+
+ ret = -ENOTDIR;
+ if (keyring->type != &key_type_keyring)
+ goto error;
+
+ down_write(&keyring->sem);
+
+ klist = keyring->payload.subscriptions;
+ if (klist) {
+ /* search the keyring for the key */
+ for (loop = 0; loop < klist->nkeys; loop++)
+ if (klist->keys[loop] == key)
+ goto key_is_present;
+ }
+
+ up_write(&keyring->sem);
+ ret = -ENOENT;
+ goto error;
+
+ key_is_present:
+ /* adjust the user's quota */
+ key_payload_reserve(keyring,
+ keyring->datalen - KEYQUOTA_LINK_BYTES);
+
+ /* shuffle down the key pointers
+ * - it might be worth shrinking the allocated memory, but that runs
+ * the risk of ENOMEM as we would have to copy
+ */
+ write_lock(&keyring->lock);
+
+ klist->nkeys--;
+ if (loop < klist->nkeys)
+ memcpy(&klist->keys[loop],
+ &klist->keys[loop + 1],
+ (klist->nkeys - loop) * sizeof(struct key *));
+
+ write_unlock(&keyring->lock);
+
+ up_write(&keyring->sem);
+ key_put(key);
+ ret = 0;
+
+ error:
+ return ret;
+
+} /* end key_unlink() */
+
+EXPORT_SYMBOL(key_unlink);
+
+/*****************************************************************************/
+/*
+ * clear the specified process keyring
+ * - implements keyctl(KEYCTL_CLEAR)
+ */
+int keyring_clear(struct key *keyring)
+{
+ struct keyring_list *klist;
+ int loop, ret;
+
+ ret = -ENOTDIR;
+ if (keyring->type == &key_type_keyring) {
+ /* detach the pointer block with the locks held */
+ down_write(&keyring->sem);
+
+ klist = keyring->payload.subscriptions;
+ if (klist) {
+ /* adjust the quota */
+ key_payload_reserve(keyring,
+ sizeof(struct keyring_list));
+
+ write_lock(&keyring->lock);
+ keyring->payload.subscriptions = NULL;
+ write_unlock(&keyring->lock);
+ }
+
+ up_write(&keyring->sem);
+
+ /* free the keys after the locks have been dropped */
+ if (klist) {
+ for (loop = klist->nkeys - 1; loop >= 0; loop--)
+ key_put(klist->keys[loop]);
+
+ kfree(klist);
+ }
+
+ ret = 0;
+ }
+
+ return ret;
+
+} /* end keyring_clear() */
+
+EXPORT_SYMBOL(keyring_clear);
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