--- /dev/null
+ ===================
+ KEY REQUEST SERVICE
+ ===================
+
+The key request service is part of the key retention service (refer to
+Documentation/keys.txt). This document explains more fully how that the
+requesting algorithm works.
+
+The process starts by either the kernel requesting a service by calling
+request_key():
+
+ struct key *request_key(const struct key_type *type,
+ const char *description,
+ const char *callout_string);
+
+Or by userspace invoking the request_key system call:
+
+ key_serial_t request_key(const char *type,
+ const char *description,
+ const char *callout_info,
+ key_serial_t dest_keyring);
+
+The main difference between the two access points is that the in-kernel
+interface does not need to link the key to a keyring to prevent it from being
+immediately destroyed. The kernel interface returns a pointer directly to the
+key, and it's up to the caller to destroy the key.
+
+The userspace interface links the key to a keyring associated with the process
+to prevent the key from going away, and returns the serial number of the key to
+the caller.
+
+
+===========
+THE PROCESS
+===========
+
+A request proceeds in the following manner:
+
+ (1) Process A calls request_key() [the userspace syscall calls the kernel
+ interface].
+
+ (2) request_key() searches the process's subscribed keyrings to see if there's
+ a suitable key there. If there is, it returns the key. If there isn't, and
+ callout_info is not set, an error is returned. Otherwise the process
+ proceeds to the next step.
+
+ (3) request_key() sees that A doesn't have the desired key yet, so it creates
+ two things:
+
+ (a) An uninstantiated key U of requested type and description.
+
+ (b) An authorisation key V that refers to key U and notes that process A
+ is the context in which key U should be instantiated and secured, and
+ from which associated key requests may be satisfied.
+
+ (4) request_key() then forks and executes /sbin/request-key with a new session
+ keyring that contains a link to auth key V.
+
+ (5) /sbin/request-key execs an appropriate program to perform the actual
+ instantiation.
+
+ (6) The program may want to access another key from A's context (say a
+ Kerberos TGT key). It just requests the appropriate key, and the keyring
+ search notes that the session keyring has auth key V in its bottom level.
+
+ This will permit it to then search the keyrings of process A with the
+ UID, GID, groups and security info of process A as if it was process A,
+ and come up with key W.
+
+ (7) The program then does what it must to get the data with which to
+ instantiate key U, using key W as a reference (perhaps it contacts a
+ Kerberos server using the TGT) and then instantiates key U.
+
+ (8) Upon instantiating key U, auth key V is automatically revoked so that it
+ may not be used again.
+
+ (9) The program then exits 0 and request_key() deletes key V and returns key
+ U to the caller.
+
+This also extends further. If key W (step 5 above) didn't exist, key W would be
+created uninstantiated, another auth key (X) would be created [as per step 3]
+and another copy of /sbin/request-key spawned [as per step 4]; but the context
+specified by auth key X will still be process A, as it was in auth key V.
+
+This is because process A's keyrings can't simply be attached to
+/sbin/request-key at the appropriate places because (a) execve will discard two
+of them, and (b) it requires the same UID/GID/Groups all the way through.
+
+
+======================
+NEGATIVE INSTANTIATION
+======================
+
+Rather than instantiating a key, it is possible for the possessor of an
+authorisation key to negatively instantiate a key that's under construction.
+This is a short duration placeholder that causes any attempt at re-requesting
+the key whilst it exists to fail with error ENOKEY.
+
+This is provided to prevent excessive repeated spawning of /sbin/request-key
+processes for a key that will never be obtainable.
+
+Should the /sbin/request-key process exit anything other than 0 or die on a
+signal, the key under construction will be automatically negatively
+instantiated for a short amount of time.
+
+
+====================
+THE SEARCH ALGORITHM
+====================
+
+A search of any particular keyring proceeds in the following fashion:
+
+ (1) When the key management code searches for a key (keyring_search_aux) it
+ firstly calls key_permission(SEARCH) on the keyring it's starting with,
+ if this denies permission, it doesn't search further.
+
+ (2) It considers all the non-keyring keys within that keyring and, if any key
+ matches the criteria specified, calls key_permission(SEARCH) on it to see
+ if the key is allowed to be found. If it is, that key is returned; if
+ not, the search continues, and the error code is retained if of higher
+ priority than the one currently set.
+
+ (3) It then considers all the keyring-type keys in the keyring it's currently
+ searching. It calls key_permission(SEARCH) on each keyring, and if this
+ grants permission, it recurses, executing steps (2) and (3) on that
+ keyring.
+
+The process stops immediately a valid key is found with permission granted to
+use it. Any error from a previous match attempt is discarded and the key is
+returned.
+
+When search_process_keyrings() is invoked, it performs the following searches
+until one succeeds:
+
+ (1) If extant, the process's thread keyring is searched.
+
+ (2) If extant, the process's process keyring is searched.
+
+ (3) The process's session keyring is searched.
+
+ (4) If the process has a request_key() authorisation key in its session
+ keyring then:
+
+ (a) If extant, the calling process's thread keyring is searched.
+
+ (b) If extant, the calling process's process keyring is searched.
+
+ (c) The calling process's session keyring is searched.
+
+The moment one succeeds, all pending errors are discarded and the found key is
+returned.
+
+Only if all these fail does the whole thing fail with the highest priority
+error. Note that several errors may have come from LSM.
+
+The error priority is:
+
+ EKEYREVOKED > EKEYEXPIRED > ENOKEY
+
+EACCES/EPERM are only returned on a direct search of a specific keyring where
+the basal keyring does not grant Search permission.
/sbin/request-key will be invoked in an attempt to obtain a key. The
callout_info string will be passed as an argument to the program.
+ See also Documentation/keys-request-key.txt.
+
The keyctl syscall functions are:
(*) Read the payload data from a key:
- key_serial_t keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer,
- size_t buflen);
+ long keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer,
+ size_t buflen);
This function attempts to read the payload data from the specified key
into the buffer. The process must have read permission on the key to
(*) Instantiate a partially constructed key.
- key_serial_t keyctl(KEYCTL_INSTANTIATE, key_serial_t key,
- const void *payload, size_t plen,
- key_serial_t keyring);
+ long keyctl(KEYCTL_INSTANTIATE, key_serial_t key,
+ const void *payload, size_t plen,
+ key_serial_t keyring);
If the kernel calls back to userspace to complete the instantiation of a
key, userspace should use this call to supply data for the key before the
(*) Negatively instantiate a partially constructed key.
- key_serial_t keyctl(KEYCTL_NEGATE, key_serial_t key,
- unsigned timeout, key_serial_t keyring);
+ long keyctl(KEYCTL_NEGATE, key_serial_t key,
+ unsigned timeout, key_serial_t keyring);
If the kernel calls back to userspace to complete the instantiation of a
key, userspace should use this call mark the key as negative before the
If successful, the key will have been attached to the default keyring for
implicitly obtained request-key keys, as set by KEYCTL_SET_REQKEY_KEYRING.
+ See also Documentation/keys-request-key.txt.
+
(*) When it is no longer required, the key should be released using:
* Some fixup code to make everybody happy (TM).
*/
+#ifdef CONFIG_CARDBUS
/**
* set/clear various test bits:
* Defaults to clear the bit.
config_writeb(socket, ENE_TEST_C9, test_c9);
}
-
static int ene_override(struct yenta_socket *socket)
{
/* install tune_bridge() function */
return ti1250_override(socket);
}
+#else
+# define ene_override ti1250_override
+#endif
#endif /* _LINUX_TI113X_H */
if (nd->last_type != LAST_NORM)
goto exit;
if (nd->last.name[nd->last.len]) {
- putname(nd->last.name);
+ __putname(nd->last.name);
goto exit;
}
error = -ELOOP;
if (count++==32) {
- putname(nd->last.name);
+ __putname(nd->last.name);
goto exit;
}
dir = nd->dentry;
down(&dir->d_inode->i_sem);
path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
path.mnt = nd->mnt;
- putname(nd->last.name);
+ __putname(nd->last.name);
goto do_last;
}
struct key *keys[0];
};
-
/*
* check to see whether permission is granted to use a key in the desired way
*/
-static inline int key_permission(const key_ref_t key_ref, key_perm_t perm)
-{
- struct key *key = key_ref_to_ptr(key_ref);
- key_perm_t kperm;
-
- if (is_key_possessed(key_ref))
- kperm = key->perm >> 24;
- else if (key->uid == current->fsuid)
- kperm = key->perm >> 16;
- else if (key->gid != -1 &&
- key->perm & KEY_GRP_ALL &&
- in_group_p(key->gid)
- )
- kperm = key->perm >> 8;
- else
- kperm = key->perm;
-
- kperm = kperm & perm & KEY_ALL;
-
- return kperm == perm;
-}
-
-/*
- * check to see whether permission is granted to use a key in at least one of
- * the desired ways
- */
-static inline int key_any_permission(const key_ref_t key_ref, key_perm_t perm)
-{
- struct key *key = key_ref_to_ptr(key_ref);
- key_perm_t kperm;
-
- if (is_key_possessed(key_ref))
- kperm = key->perm >> 24;
- else if (key->uid == current->fsuid)
- kperm = key->perm >> 16;
- else if (key->gid != -1 &&
- key->perm & KEY_GRP_ALL &&
- in_group_p(key->gid)
- )
- kperm = key->perm >> 8;
- else
- kperm = key->perm;
+extern int key_task_permission(const key_ref_t key_ref,
+ struct task_struct *context,
+ key_perm_t perm);
- kperm = kperm & perm & KEY_ALL;
-
- return kperm != 0;
-}
-
-static inline int key_task_groups_search(struct task_struct *tsk, gid_t gid)
-{
- int ret;
-
- task_lock(tsk);
- ret = groups_search(tsk->group_info, gid);
- task_unlock(tsk);
- return ret;
-}
-
-static inline int key_task_permission(const key_ref_t key_ref,
- struct task_struct *context,
- key_perm_t perm)
+static inline int key_permission(const key_ref_t key_ref, key_perm_t perm)
{
- struct key *key = key_ref_to_ptr(key_ref);
- key_perm_t kperm;
-
- if (is_key_possessed(key_ref)) {
- kperm = key->perm >> 24;
- }
- else if (key->uid == context->fsuid) {
- kperm = key->perm >> 16;
- }
- else if (key->gid != -1 &&
- key->perm & KEY_GRP_ALL && (
- key->gid == context->fsgid ||
- key_task_groups_search(context, key->gid)
- )
- ) {
- kperm = key->perm >> 8;
- }
- else {
- kperm = key->perm;
- }
-
- kperm = kperm & perm & KEY_ALL;
-
- return kperm == perm;
-
+ return key_task_permission(key_ref, current, perm);
}
extern key_ref_t lookup_user_key(struct task_struct *context,
* is to alert stop-signal processing code when another
* processor has come along and cleared the flag.
*/
- tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
+ if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
+ tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
}
if ( signr &&
((info->si_code & __SI_MASK) == __SI_TIMER) &&
key.o \
keyring.o \
keyctl.o \
+ permission.o \
process_keys.o \
request_key.o \
request_key_auth.o \
--- /dev/null
+/* permission.c: key permission determination
+ *
+ * Copyright (C) 2005 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 "internal.h"
+
+/*****************************************************************************/
+/*
+ * check to see whether permission is granted to use a key in the desired way,
+ * but permit the security modules to override
+ */
+int key_task_permission(const key_ref_t key_ref,
+ struct task_struct *context,
+ key_perm_t perm)
+{
+ struct key *key;
+ key_perm_t kperm;
+ int ret;
+
+ key = key_ref_to_ptr(key_ref);
+
+ /* use the second 8-bits of permissions for keys the caller owns */
+ if (key->uid == context->fsuid) {
+ kperm = key->perm >> 16;
+ goto use_these_perms;
+ }
+
+ /* use the third 8-bits of permissions for keys the caller has a group
+ * membership in common with */
+ if (key->gid != -1 && key->perm & KEY_GRP_ALL) {
+ if (key->gid == context->fsgid) {
+ kperm = key->perm >> 8;
+ goto use_these_perms;
+ }
+
+ task_lock(context);
+ ret = groups_search(context->group_info, key->gid);
+ task_unlock(context);
+
+ if (ret) {
+ kperm = key->perm >> 8;
+ goto use_these_perms;
+ }
+ }
+
+ /* otherwise use the least-significant 8-bits */
+ kperm = key->perm;
+
+use_these_perms:
+ /* use the top 8-bits of permissions for keys the caller possesses
+ * - possessor permissions are additive with other permissions
+ */
+ if (is_key_possessed(key_ref))
+ kperm |= key->perm >> 24;
+
+ kperm = kperm & perm & KEY_ALL;
+
+ return kperm == perm;
+
+} /* end key_task_permission() */
+
+EXPORT_SYMBOL(key_task_permission);
* 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.
+ *
+ * See Documentation/keys-request-key.txt
*/
#include <linux/module.h>
* 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.
+ *
+ * See Documentation/keys-request-key.txt
*/
#include <linux/module.h>
kenter("{%d}", key->serial);
key_put(rka->target_key);
+ kfree(rka);
} /* end request_key_auth_destroy() */
projects / linux-2.6-omap-h63xx.git / commitdiff