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提交 973c9f4f 编写于 作者: D David Howells 提交者： Linus Torvalds
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KEYS: Fix up comments in key management code 

Fix up comments in the key management code.  No functional changes.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 a8b17ed0
隐藏空白更改
内联 并排
Showing with 777 addition and 366 deletion
security/keys/compat.c
浏览文件 @ 973c9f4f
/* compat.c: 32-bit compatibility syscall for 64-bit systems
/* 32-bit compatibility syscall for 64-bit systems
*
* Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -15,11 +15,12 @@
#include "internal.h"
/*
* the key control system call, 32-bit compatibility version for 64-bit archs
* - this should only be called if the 64-bit arch uses weird pointers in
* 32-bit mode or doesn't guarantee that the top 32-bits of the argument
* registers on taking a 32-bit syscall are zero
* - if you can, you should call sys_keyctl directly
* The key control system call, 32-bit compatibility version for 64-bit archs
*
* This should only be called if the 64-bit arch uses weird pointers in 32-bit
* mode or doesn't guarantee that the top 32-bits of the argument registers on
* taking a 32-bit syscall are zero. If you can, you should call sys_keyctl()
* directly.
*/
asmlinkage long compat_sys_keyctl(u32 option,
u32 arg2, u32 arg3, u32 arg4, u32 arg5)
......
security/keys/gc.c
浏览文件 @ 973c9f4f
......@@ -32,8 +32,8 @@ static time_t key_gc_next_run = LONG_MAX;
static time_t key_gc_new_timer;
/*
* Schedule a garbage collection run
* - precision isn't particularly important
* Schedule a garbage collection run.
* - time precision isn't particularly important
*/
void key_schedule_gc(time_t gc_at)
{
......@@ -61,8 +61,9 @@ static void key_gc_timer_func(unsigned long data)
}
/*
* Garbage collect pointers from a keyring
* - return true if we altered the keyring
* Garbage collect pointers from a keyring.
*
* Return true if we altered the keyring.
*/
static bool key_gc_keyring(struct key *keyring, time_t limit)
__releases(key_serial_lock)
......@@ -107,9 +108,8 @@ static bool key_gc_keyring(struct key *keyring, time_t limit)
}
/*
* Garbage collector for keys
* - this involves scanning the keyrings for dead, expired and revoked keys
* that have overstayed their welcome
* Garbage collector for keys. This involves scanning the keyrings for dead,
* expired and revoked keys that have overstayed their welcome
*/
static void key_garbage_collector(struct work_struct *work)
{
......
security/keys/internal.h
浏览文件 @ 973c9f4f
/* internal.h: authentication token and access key management internal defs
/* Authentication token and access key management internal defs
*
* Copyright (C) 2003-5, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -35,10 +35,12 @@ extern struct key_type key_type_user;
/*****************************************************************************/
/*
* keep track of keys for a user
* - this needs to be separate to user_struct to avoid a refcount-loop
* (user_struct pins some keyrings which pin this struct)
* - this also keeps track of keys under request from userspace for this UID
* Keep track of keys for a user.
*
* This needs to be separate to user_struct to avoid a refcount-loop
* (user_struct pins some keyrings which pin this struct).
*
* We also keep track of keys under request from userspace for this UID here.
*/
struct key_user {
struct rb_node node;
......@@ -62,7 +64,7 @@ extern struct key_user *key_user_lookup(uid_t uid,
extern void key_user_put(struct key_user *user);
/*
* key quota limits
* Key quota limits.
* - root has its own separate limits to everyone else
*/
extern unsigned key_quota_root_maxkeys;
......@@ -146,13 +148,13 @@ extern unsigned key_gc_delay;
extern void keyring_gc(struct key *keyring, time_t limit);
extern void key_schedule_gc(time_t expiry_at);
/*
* check to see whether permission is granted to use a key in the desired way
*/
extern int key_task_permission(const key_ref_t key_ref,
const struct cred *cred,
key_perm_t perm);
/*
* 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)
{
return key_task_permission(key_ref, current_cred(), perm);
......@@ -168,7 +170,7 @@ static inline int key_permission(const key_ref_t key_ref, key_perm_t perm)
#define KEY_ALL 0x3f /* all the above permissions */
/*
* request_key authorisation
* Authorisation record for request_key().
*/
struct request_key_auth {
struct key *target_key;
......@@ -188,7 +190,7 @@ extern struct key *request_key_auth_new(struct key *target,
extern struct key *key_get_instantiation_authkey(key_serial_t target_id);
/*
* keyctl functions
* keyctl() functions
*/
extern long keyctl_get_keyring_ID(key_serial_t, int);
extern long keyctl_join_session_keyring(const char __user *);
......@@ -214,7 +216,7 @@ extern long keyctl_get_security(key_serial_t keyid, char __user *buffer,
extern long keyctl_session_to_parent(void);
/*
* debugging key validation
* Debugging key validation
*/
#ifdef KEY_DEBUGGING
extern void __key_check(const struct key *);
......
security/keys/key.c
浏览文件 @ 973c9f4f
......@@ -39,10 +39,10 @@ static DECLARE_RWSEM(key_types_sem);
static void key_cleanup(struct work_struct *work);
static DECLARE_WORK(key_cleanup_task, key_cleanup);
/* we serialise key instantiation and link */
/* We serialise key instantiation and link */
DEFINE_MUTEX(key_construction_mutex);
/* any key who's type gets unegistered will be re-typed to this */
/* Any key who's type gets unegistered will be re-typed to this */
static struct key_type key_type_dead = {
.name = "dead",
};
......@@ -57,8 +57,8 @@ void __key_check(const struct key *key)
#endif
/*
* get the key quota record for a user, allocating a new record if one doesn't
* already exist
* Get the key quota record for a user, allocating a new record if one doesn't
* already exist.
*/
struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
{
......@@ -66,7 +66,7 @@ struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
struct rb_node *parent = NULL;
struct rb_node **p;
try_again:
try_again:
p = &key_user_tree.rb_node;
spin_lock(&key_user_lock);
......@@ -123,16 +123,16 @@ struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
goto out;
/* okay - we found a user record for this UID */
found:
found:
atomic_inc(&user->usage);
spin_unlock(&key_user_lock);
kfree(candidate);
out:
out:
return user;
}
/*
* dispose of a user structure
* Dispose of a user structure
*/
void key_user_put(struct key_user *user)
{
......@@ -146,9 +146,8 @@ void key_user_put(struct key_user *user)
}
/*
* assign a key the next unique serial number
* - these are assigned randomly to avoid security issues through covert
* channel problems
* Allocate a serial number for a key. These are assigned randomly to avoid
* security issues through covert channel problems.
*/
static inline void key_alloc_serial(struct key *key)
{
......@@ -208,14 +207,34 @@ static inline void key_alloc_serial(struct key *key)
}
}
/*
* allocate a key of the specified type
* - update the user's quota to reflect the existence of the key
* - called from a key-type operation with key_types_sem read-locked by
* key_create_or_update()
* - this prevents unregistration of the key type
* - upon return the key is as yet uninstantiated; the caller needs to either
* instantiate the key or discard it before returning
/**
* key_alloc - Allocate a key of the specified type.
* @type: The type of key to allocate.
* @desc: The key description to allow the key to be searched out.
* @uid: The owner of the new key.
* @gid: The group ID for the new key's group permissions.
* @cred: The credentials specifying UID namespace.
* @perm: The permissions mask of the new key.
* @flags: Flags specifying quota properties.
*
* Allocate a key of the specified type with the attributes given. The key is
* returned in an uninstantiated state and the caller needs to instantiate the
* key before returning.
*
* The user's key count quota is updated to reflect the creation of the key and
* the user's key data quota has the default for the key type reserved. The
* instantiation function should amend this as necessary. If insufficient
* quota is available, -EDQUOT will be returned.
*
* The LSM security modules can prevent a key being created, in which case
* -EACCES will be returned.
*
* Returns a pointer to the new key if successful and an error code otherwise.
*
* Note that the caller needs to ensure the key type isn't uninstantiated.
* Internally this can be done by locking key_types_sem. Externally, this can
* be done by either never unregistering the key type, or making sure
* key_alloc() calls don't race with module unloading.
*/
struct key *key_alloc(struct key_type *type, const char *desc,
uid_t uid, gid_t gid, const struct cred *cred,
......@@ -338,11 +357,18 @@ struct key *key_alloc(struct key_type *type, const char *desc,
key = ERR_PTR(-EDQUOT);
goto error;
}
EXPORT_SYMBOL(key_alloc);
/*
* reserve an amount of quota for the key's payload
/**
* key_payload_reserve - Adjust data quota reservation for the key's payload
* @key: The key to make the reservation for.
* @datalen: The amount of data payload the caller now wants.
*
* Adjust the amount of the owning user's key data quota that a key reserves.
* If the amount is increased, then -EDQUOT may be returned if there isn't
* enough free quota available.
*
* If successful, 0 is returned.
*/
int key_payload_reserve(struct key *key, size_t datalen)
{
......@@ -376,12 +402,13 @@ int key_payload_reserve(struct key *key, size_t datalen)
return ret;
}
EXPORT_SYMBOL(key_payload_reserve);
/*
* instantiate a key and link it into the target keyring atomically
* - called with the target keyring's semaphore writelocked
* Instantiate a key and link it into the target keyring atomically. Must be
* called with the target keyring's semaphore writelocked. The target key's
* semaphore need not be locked as instantiation is serialised by
* key_construction_mutex.
*/
static int __key_instantiate_and_link(struct key *key,
const void *data,
......@@ -432,8 +459,21 @@ static int __key_instantiate_and_link(struct key *key,
return ret;
}
/*
* instantiate a key and link it into the target keyring atomically
/**
* key_instantiate_and_link - Instantiate a key and link it into the keyring.
* @key: The key to instantiate.
* @data: The data to use to instantiate the keyring.
* @datalen: The length of @data.
* @keyring: Keyring to create a link in on success (or NULL).
* @authkey: The authorisation token permitting instantiation.
*
* Instantiate a key that's in the uninstantiated state using the provided data
* and, if successful, link it in to the destination keyring if one is
* supplied.
*
* If successful, 0 is returned, the authorisation token is revoked and anyone
* waiting for the key is woken up. If the key was already instantiated,
* -EBUSY will be returned.
*/
int key_instantiate_and_link(struct key *key,
const void *data,
......@@ -462,8 +502,24 @@ int key_instantiate_and_link(struct key *key,
EXPORT_SYMBOL(key_instantiate_and_link);
/*
* negatively instantiate a key and link it into the target keyring atomically
/**
* key_negate_and_link - Negatively instantiate a key and link it into the keyring.
* @key: The key to instantiate.
* @timeout: The timeout on the negative key.
* @keyring: Keyring to create a link in on success (or NULL).
* @authkey: The authorisation token permitting instantiation.
*
* Negatively instantiate a key that's in the uninstantiated state and, if
* successful, set its timeout and link it in to the destination keyring if one
* is supplied. The key and any links to the key will be automatically garbage
* collected after the timeout expires.
*
* Negative keys are used to rate limit repeated request_key() calls by causing
* them to return -ENOKEY until the negative key expires.
*
* If successful, 0 is returned, the authorisation token is revoked and anyone
* waiting for the key is woken up. If the key was already instantiated,
* -EBUSY will be returned.
*/
int key_negate_and_link(struct key *key,
unsigned timeout,
......@@ -525,15 +581,18 @@ int key_negate_and_link(struct key *key,
EXPORT_SYMBOL(key_negate_and_link);
/*
* do cleaning up in process context so that we don't have to disable
* interrupts all over the place
* Garbage collect keys in process context so that we don't have to disable
* interrupts all over the place.
*
* key_put() schedules this rather than trying to do the cleanup itself, which
* means key_put() doesn't have to sleep.
*/
static void key_cleanup(struct work_struct *work)
{
struct rb_node *_n;
struct key *key;
go_again:
go_again:
/* look for a dead key in the tree */
spin_lock(&key_serial_lock);
......@@ -547,7 +606,7 @@ static void key_cleanup(struct work_struct *work)
spin_unlock(&key_serial_lock);
return;
found_dead_key:
found_dead_key:
/* we found a dead key - once we've removed it from the tree, we can
* drop the lock */
rb_erase(&key->serial_node, &key_serial_tree);
......@@ -586,10 +645,13 @@ static void key_cleanup(struct work_struct *work)
goto go_again;
}
/*
* dispose of a reference to a key
* - when all the references are gone, we schedule the cleanup task to come and
* pull it out of the tree in definite process context
/**
* key_put - Discard a reference to a key.
* @key: The key to discard a reference from.
*
* Discard a reference to a key, and when all the references are gone, we
* schedule the cleanup task to come and pull it out of the tree in process
* context at some later time.
*/
void key_put(struct key *key)
{
......@@ -600,11 +662,10 @@ void key_put(struct key *key)
schedule_work(&key_cleanup_task);
}
}
EXPORT_SYMBOL(key_put);
/*
* find a key by its serial number
* Find a key by its serial number.
*/
struct key *key_lookup(key_serial_t id)
{
......@@ -626,11 +687,11 @@ struct key *key_lookup(key_serial_t id)
goto found;
}
not_found:
not_found:
key = ERR_PTR(-ENOKEY);
goto error;
found:
found:
/* pretend it doesn't exist if it is awaiting deletion */
if (atomic_read(&key->usage) == 0)
goto not_found;
......@@ -640,14 +701,16 @@ struct key *key_lookup(key_serial_t id)
*/
atomic_inc(&key->usage);
error:
error:
spin_unlock(&key_serial_lock);
return key;
}
/*
* find and lock the specified key type against removal
* - we return with the sem readlocked
* Find and lock the specified key type against removal.
*
* We return with the sem read-locked if successful. If the type wasn't
* available -ENOKEY is returned instead.
*/
struct key_type *key_type_lookup(const char *type)
{
......@@ -665,12 +728,12 @@ struct key_type *key_type_lookup(const char *type)
up_read(&key_types_sem);
ktype = ERR_PTR(-ENOKEY);
found_kernel_type:
found_kernel_type:
return ktype;
}
/*
* unlock a key type
* Unlock a key type locked by key_type_lookup().
*/
void key_type_put(struct key_type *ktype)
{
......@@ -678,9 +741,10 @@ void key_type_put(struct key_type *ktype)
}
/*
* attempt to update an existing key
* - the key has an incremented refcount
* - we need to put the key if we get an error
* Attempt to update an existing key.
*
* The key is given to us with an incremented refcount that we need to discard
* if we get an error.
*/
static inline key_ref_t __key_update(key_ref_t key_ref,
const void *payload, size_t plen)
......@@ -717,9 +781,30 @@ static inline key_ref_t __key_update(key_ref_t key_ref,
goto out;
}
/*
* search the specified keyring for a key of the same description; if one is
* found, update it, otherwise add a new one
/**
* key_create_or_update - Update or create and instantiate a key.
* @keyring_ref: A pointer to the destination keyring with possession flag.
* @type: The type of key.
* @description: The searchable description for the key.
* @payload: The data to use to instantiate or update the key.
* @plen: The length of @payload.
* @perm: The permissions mask for a new key.
* @flags: The quota flags for a new key.
*
* Search the destination keyring for a key of the same description and if one
* is found, update it, otherwise create and instantiate a new one and create a
* link to it from that keyring.
*
* If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
* concocted.
*
* Returns a pointer to the new key if successful, -ENODEV if the key type
* wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
* caller isn't permitted to modify the keyring or the LSM did not permit
* creation of the key.
*
* On success, the possession flag from the keyring ref will be tacked on to
* the key ref before it is returned.
*/
key_ref_t key_create_or_update(key_ref_t keyring_ref,
const char *type,
......@@ -827,11 +912,20 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
key_ref = __key_update(key_ref, payload, plen);
goto error;
}
EXPORT_SYMBOL(key_create_or_update);
/*
* update a key
/**
* key_update - Update a key's contents.
* @key_ref: The pointer (plus possession flag) to the key.
* @payload: The data to be used to update the key.
* @plen: The length of @payload.
*
* Attempt to update the contents of a key with the given payload data. The
* caller must be granted Write permission on the key. Negative keys can be
* instantiated by this method.
*
* Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
* type does not support updating. The key type may return other errors.
*/
int key_update(key_ref_t key_ref, const void *payload, size_t plen)
{
......@@ -861,11 +955,16 @@ int key_update(key_ref_t key_ref, const void *payload, size_t plen)
error:
return ret;
}
EXPORT_SYMBOL(key_update);
/*
* revoke a key
/**
* key_revoke - Revoke a key.
* @key: The key to be revoked.
*
* Mark a key as being revoked and ask the type to free up its resources. The
* revocation timeout is set and the key and all its links will be
* automatically garbage collected after key_gc_delay amount of time if they
* are not manually dealt with first.
*/
void key_revoke(struct key *key)
{
......@@ -894,11 +993,15 @@ void key_revoke(struct key *key)
up_write(&key->sem);
}
EXPORT_SYMBOL(key_revoke);
/*
* register a type of key
/**
* register_key_type - Register a type of key.
* @ktype: The new key type.
*
* Register a new key type.
*
* Returns 0 on success or -EEXIST if a type of this name already exists.
*/
int register_key_type(struct key_type *ktype)
{
......@@ -918,15 +1021,19 @@ int register_key_type(struct key_type *ktype)
list_add(&ktype->link, &key_types_list);
ret = 0;
out:
out:
up_write(&key_types_sem);
return ret;
}
EXPORT_SYMBOL(register_key_type);
/*
* unregister a type of key
/**
* unregister_key_type - Unregister a type of key.
* @ktype: The key type.
*
* Unregister a key type and mark all the extant keys of this type as dead.
* Those keys of this type are then destroyed to get rid of their payloads and
* they and their links will be garbage collected as soon as possible.
*/
void unregister_key_type(struct key_type *ktype)
{
......@@ -974,11 +1081,10 @@ void unregister_key_type(struct key_type *ktype)
key_schedule_gc(0);
}
EXPORT_SYMBOL(unregister_key_type);
/*
* initialise the key management stuff
* Initialise the key management state.
*/
void __init key_init(void)
{
......
security/keys/keyctl.c
浏览文件 @ 973c9f4f
/* keyctl.c: userspace keyctl operations
/* Userspace key control operations
*
* Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -31,27 +31,24 @@ static int key_get_type_from_user(char *type,
int ret;
ret = strncpy_from_user(type, _type, len);
if (ret < 0)
return ret;
if (ret == 0 || ret >= len)
return -EINVAL;
if (type[0] == '.')
return -EPERM;
type[len - 1] = '\0';
return 0;
}
/*
* extract the description of a new key from userspace and either add it as a
* new key to the specified keyring or update a matching key in that keyring
* - the keyring must be writable
* - returns the new key's serial number
* - implements add_key()
* Extract the description of a new key from userspace and either add it as a
* new key to the specified keyring or update a matching key in that keyring.
*
* The keyring must be writable so that we can attach the key to it.
*
* If successful, the new key's serial number is returned, otherwise an error
* code is returned.
*/
SYSCALL_DEFINE5(add_key, const char __user *, _type,
const char __user *, _description,
......@@ -134,14 +131,17 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type,
}
/*
* search the process keyrings for a matching key
* - nested keyrings may also be searched if they have Search permission
* - if a key is found, it will be attached to the destination keyring if
* there's one specified
* - /sbin/request-key will be invoked if _callout_info is non-NULL
* - the _callout_info string will be passed to /sbin/request-key
* - if the _callout_info string is empty, it will be rendered as "-"
* - implements request_key()
* Search the process keyrings and keyring trees linked from those for a
* matching key. Keyrings must have appropriate Search permission to be
* searched.
*
* If a key is found, it will be attached to the destination keyring if there's
* one specified and the serial number of the key will be returned.
*
* If no key is found, /sbin/request-key will be invoked if _callout_info is
* non-NULL in an attempt to create a key. The _callout_info string will be
* passed to /sbin/request-key to aid with completing the request. If the
* _callout_info string is "" then it will be changed to "-".
*/
SYSCALL_DEFINE4(request_key, const char __user *, _type,
const char __user *, _description,
......@@ -222,9 +222,11 @@ SYSCALL_DEFINE4(request_key, const char __user *, _type,
}
/*
* get the ID of the specified process keyring
* - the keyring must have search permission to be found
* - implements keyctl(KEYCTL_GET_KEYRING_ID)
* Get the ID of the specified process keyring.
*
* The requested keyring must have search permission to be found.
*
* If successful, the ID of the requested keyring will be returned.
*/
long keyctl_get_keyring_ID(key_serial_t id, int create)
{
......@@ -243,12 +245,17 @@ long keyctl_get_keyring_ID(key_serial_t id, int create)
key_ref_put(key_ref);
error:
return ret;
} /* end keyctl_get_keyring_ID() */
}
/*
* join the session keyring
* - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING)
* Join a (named) session keyring.
*
* Create and join an anonymous session keyring or join a named session
* keyring, creating it if necessary. A named session keyring must have Search
* permission for it to be joined. Session keyrings without this permit will
* be skipped over.
*
* If successful, the ID of the joined session keyring will be returned.
*/
long keyctl_join_session_keyring(const char __user *_name)
{
......@@ -274,9 +281,14 @@ long keyctl_join_session_keyring(const char __user *_name)
}
/*
* update a key's data payload
* - the key must be writable
* - implements keyctl(KEYCTL_UPDATE)
* Update a key's data payload from the given data.
*
* The key must grant the caller Write permission and the key type must support
* updating for this to work. A negative key can be positively instantiated
* with this call.
*
* If successful, 0 will be returned. If the key type does not support
* updating, then -EOPNOTSUPP will be returned.
*/
long keyctl_update_key(key_serial_t id,
const void __user *_payload,
......@@ -321,9 +333,14 @@ long keyctl_update_key(key_serial_t id,
}
/*
* revoke a key
* - the key must be writable
* - implements keyctl(KEYCTL_REVOKE)
* Revoke a key.
*
* The key must be grant the caller Write or Setattr permission for this to
* work. The key type should give up its quota claim when revoked. The key
* and any links to the key will be automatically garbage collected after a
* certain amount of time (/proc/sys/kernel/keys/gc_delay).
*
* If successful, 0 is returned.
*/
long keyctl_revoke_key(key_serial_t id)
{
......@@ -351,9 +368,11 @@ long keyctl_revoke_key(key_serial_t id)
}
/*
* clear the specified process keyring
* - the keyring must be writable
* - implements keyctl(KEYCTL_CLEAR)
* Clear the specified keyring, creating an empty process keyring if one of the
* special keyring IDs is used.
*
* The keyring must grant the caller Write permission for this to work. If
* successful, 0 will be returned.
*/
long keyctl_keyring_clear(key_serial_t ringid)
{
......@@ -374,10 +393,15 @@ long keyctl_keyring_clear(key_serial_t ringid)
}
/*
* link a key into a keyring
* - the keyring must be writable
* - the key must be linkable
* - implements keyctl(KEYCTL_LINK)
* Create a link from a keyring to a key if there's no matching key in the
* keyring, otherwise replace the link to the matching key with a link to the
* new key.
*
* The key must grant the caller Link permission and the the keyring must grant
* the caller Write permission. Furthermore, if an additional link is created,
* the keyring's quota will be extended.
*
* If successful, 0 will be returned.
*/
long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
{
......@@ -406,10 +430,13 @@ long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
}
/*
* unlink the first attachment of a key from a keyring
* - the keyring must be writable
* - we don't need any permissions on the key
* - implements keyctl(KEYCTL_UNLINK)
* Unlink a key from a keyring.
*
* The keyring must grant the caller Write permission for this to work; the key
* itself need not grant the caller anything. If the last link to a key is
* removed then that key will be scheduled for destruction.
*
* If successful, 0 will be returned.
*/
long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
{
......@@ -438,14 +465,17 @@ long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
}
/*
* describe a user key
* - the key must have view permission
* - if there's a buffer, we place up to buflen bytes of data into it
* - unless there's an error, we return the amount of description available,
* irrespective of how much we may have copied
* - the description is formatted thus:
* Return a description of a key to userspace.
*
* The key must grant the caller View permission for this to work.
*
* If there's a buffer, we place up to buflen bytes of data into it formatted
* in the following way:
*
* type;uid;gid;perm;description<NUL>
* - implements keyctl(KEYCTL_DESCRIBE)
*
* If successful, we return the amount of description available, irrespective
* of how much we may have copied into the buffer.
*/
long keyctl_describe_key(key_serial_t keyid,
char __user *buffer,
......@@ -516,13 +546,14 @@ long keyctl_describe_key(key_serial_t keyid,
}
/*
* search the specified keyring for a matching key
* - the start keyring must be searchable
* - nested keyrings may also be searched if they are searchable
* - only keys with search permission may be found
* - if a key is found, it will be attached to the destination keyring if
* there's one specified
* - implements keyctl(KEYCTL_SEARCH)
* Search the specified keyring and any keyrings it links to for a matching
* key. Only keyrings that grant the caller Search permission will be searched
* (this includes the starting keyring). Only keys with Search permission can
* be found.
*
* If successful, the found key will be linked to the destination keyring if
* supplied and the key has Link permission, and the found key ID will be
* returned.
*/
long keyctl_keyring_search(key_serial_t ringid,
const char __user *_type,
......@@ -609,13 +640,14 @@ long keyctl_keyring_search(key_serial_t ringid,
}
/*
* read a user key's payload
* - the keyring must be readable or the key must be searchable from the
* process's keyrings
* - if there's a buffer, we place up to buflen bytes of data into it
* - unless there's an error, we return the amount of data in the key,
* irrespective of how much we may have copied
* - implements keyctl(KEYCTL_READ)
* Read a key's payload.
*
* The key must either grant the caller Read permission, or it must grant the
* caller Search permission when searched for from the process keyrings.
*
* If successful, we place up to buflen bytes of data into the buffer, if one
* is provided, and return the amount of data that is available in the key,
* irrespective of how much we copied into the buffer.
*/
long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
{
......@@ -669,10 +701,19 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
}
/*
* change the ownership of a key
* - the keyring owned by the changer
* - if the uid or gid is -1, then that parameter is not changed
* - implements keyctl(KEYCTL_CHOWN)
* Change the ownership of a key
*
* The key must grant the caller Setattr permission for this to work, though
* the key need not be fully instantiated yet. For the UID to be changed, or
* for the GID to be changed to a group the caller is not a member of, the
* caller must have sysadmin capability. If either uid or gid is -1 then that
* attribute is not changed.
*
* If the UID is to be changed, the new user must have sufficient quota to
* accept the key. The quota deduction will be removed from the old user to
* the new user should the attribute be changed.
*
* If successful, 0 will be returned.
*/
long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
{
......@@ -775,9 +816,11 @@ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
}
/*
* change the permission mask on a key
* - the keyring owned by the changer
* - implements keyctl(KEYCTL_SETPERM)
* Change the permission mask on a key.
*
* The key must grant the caller Setattr permission for this to work, though
* the key need not be fully instantiated yet. If the caller does not have
* sysadmin capability, it may only change the permission on keys that it owns.
*/
long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
{
......@@ -815,7 +858,8 @@ long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
}
/*
* get the destination keyring for instantiation
* Get the destination keyring for instantiation and check that the caller has
* Write permission on it.
*/
static long get_instantiation_keyring(key_serial_t ringid,
struct request_key_auth *rka,
......@@ -852,7 +896,7 @@ static long get_instantiation_keyring(key_serial_t ringid,
}
/*
* change the request_key authorisation key on the current process
* Change the request_key authorisation key on the current process.
*/
static int keyctl_change_reqkey_auth(struct key *key)
{
......@@ -869,8 +913,13 @@ static int keyctl_change_reqkey_auth(struct key *key)
}
/*
* instantiate the key with the specified payload, and, if one is given, link
* the key into the keyring
* Instantiate a key with the specified payload and link the key into the
* destination keyring if one is given.
*
* The caller must have the appropriate instantiation permit set for this to
* work (see keyctl_assume_authority). No other permissions are required.
*
* If successful, 0 will be returned.
*/
long keyctl_instantiate_key(key_serial_t id,
const void __user *_payload,
......@@ -948,8 +997,19 @@ long keyctl_instantiate_key(key_serial_t id,
}
/*
* negatively instantiate the key with the given timeout (in seconds), and, if
* one is given, link the key into the keyring
* Negatively instantiate the key with the given timeout (in seconds) and link
* the key into the destination keyring if one is given.
*
* The caller must have the appropriate instantiation permit set for this to
* work (see keyctl_assume_authority). No other permissions are required.
*
* The key and any links to the key will be automatically garbage collected
* after the timeout expires.
*
* Negative keys are used to rate limit repeated request_key() calls by causing
* them to return -ENOKEY until the negative key expires.
*
* If successful, 0 will be returned.
*/
long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
{
......@@ -993,8 +1053,11 @@ long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
}
/*
* set the default keyring in which request_key() will cache keys
* - return the old setting
* Read or set the default keyring in which request_key() will cache keys and
* return the old setting.
*
* If a process keyring is specified then this will be created if it doesn't
* yet exist. The old setting will be returned if successful.
*/
long keyctl_set_reqkey_keyring(int reqkey_defl)
{
......@@ -1050,7 +1113,16 @@ long keyctl_set_reqkey_keyring(int reqkey_defl)
}
/*
* set or clear the timeout for a key
* Set or clear the timeout on a key.
*
* Either the key must grant the caller Setattr permission or else the caller
* must hold an instantiation authorisation token for the key.
*
* The timeout is either 0 to clear the timeout, or a number of seconds from
* the current time. The key and any links to the key will be automatically
* garbage collected after the timeout expires.
*
* If successful, 0 is returned.
*/
long keyctl_set_timeout(key_serial_t id, unsigned timeout)
{
......@@ -1105,7 +1177,21 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout)
}
/*
* assume the authority to instantiate the specified key
* Assume (or clear) the authority to instantiate the specified key.
*
* This sets the authoritative token currently in force for key instantiation.
* This must be done for a key to be instantiated. It has the effect of making
* available all the keys from the caller of the request_key() that created a
* key to request_key() calls made by the caller of this function.
*
* The caller must have the instantiation key in their process keyrings with a
* Search permission grant available to the caller.
*
* If the ID given is 0, then the setting will be cleared and 0 returned.
*
* If the ID given has a matching an authorisation key, then that key will be
* set and its ID will be returned. The authorisation key can be read to get
* the callout information passed to request_key().
*/
long keyctl_assume_authority(key_serial_t id)
{
......@@ -1145,12 +1231,14 @@ long keyctl_assume_authority(key_serial_t id)
}
/*
* get the security label of a key
* - the key must grant us view permission
* - if there's a buffer, we place up to buflen bytes of data into it
* - unless there's an error, we return the amount of information available,
* irrespective of how much we may have copied (including the terminal NUL)
* - implements keyctl(KEYCTL_GET_SECURITY)
* Get a key's the LSM security label.
*
* The key must grant the caller View permission for this to work.
*
* If there's a buffer, then up to buflen bytes of data will be placed into it.
*
* If successful, the amount of information available will be returned,
* irrespective of how much was copied (including the terminal NUL).
*/
long keyctl_get_security(key_serial_t keyid,
char __user *buffer,
......@@ -1205,10 +1293,16 @@ long keyctl_get_security(key_serial_t keyid,
}
/*
* attempt to install the calling process's session keyring on the process's
* parent process
* - the keyring must exist and must grant us LINK permission
* - implements keyctl(KEYCTL_SESSION_TO_PARENT)
* Attempt to install the calling process's session keyring on the process's
* parent process.
*
* The keyring must exist and must grant the caller LINK permission, and the
* parent process must be single-threaded and must have the same effective
* ownership as this process and mustn't be SUID/SGID.
*
* The keyring will be emplaced on the parent when it next resumes userspace.
*
* If successful, 0 will be returned.
*/
long keyctl_session_to_parent(void)
{
......@@ -1312,7 +1406,7 @@ long keyctl_session_to_parent(void)
}
/*
* the key control system call
* The key control system call
*/
SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
unsigned long, arg4, unsigned long, arg5)
......
security/keys/keyring.c
浏览文件 @ 973c9f4f
......@@ -26,13 +26,13 @@
rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
/*
* when plumbing the depths of the key tree, this sets a hard limit set on how
* deep we're willing to go
* 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
* We keep all named keyrings in a hash to speed looking them up.
*/
#define KEYRING_NAME_HASH_SIZE (1 << 5)
......@@ -50,7 +50,9 @@ static inline unsigned keyring_hash(const char *desc)
}
/*
* the keyring type definition
* 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_instantiate(struct key *keyring,
const void *data, size_t datalen);
......@@ -71,18 +73,17 @@ struct key_type key_type_keyring = {
.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
* 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)
* 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)
{
......@@ -104,8 +105,9 @@ static void keyring_publish_name(struct key *keyring)
}
/*
* initialise a keyring
* - we object if we were given any data
* Initialise a keyring.
*
* Returns 0 on success, -EINVAL if given any data.
*/
static int keyring_instantiate(struct key *keyring,
const void *data, size_t datalen)
......@@ -123,7 +125,7 @@ static int keyring_instantiate(struct key *keyring,
}
/*
* match keyrings on their name
* Match keyrings on their name
*/
static int keyring_match(const struct key *keyring, const void *description)
{
......@@ -132,7 +134,8 @@ static int keyring_match(const struct key *keyring, const void *description)
}
/*
* dispose of the data dangling from the corpse of a keyring
* Clean up a keyring when it is destroyed. Unpublish its name if it had one
* and dispose of its data.
*/
static void keyring_destroy(struct key *keyring)
{
......@@ -160,7 +163,7 @@ static void keyring_destroy(struct key *keyring)
}
/*
* describe the keyring
* Describe a keyring for /proc.
*/
static void keyring_describe(const struct key *keyring, struct seq_file *m)
{
......@@ -181,8 +184,9 @@ static void keyring_describe(const struct key *keyring, struct seq_file *m)
}
/*
* read a list of key IDs from the keyring's contents
* - the keyring's semaphore is read-locked
* Read a list of key IDs from the keyring's contents in binary form
*
* The keyring's semaphore is read-locked by the caller.
*/
static long keyring_read(const struct key *keyring,
char __user *buffer, size_t buflen)
......@@ -233,7 +237,7 @@ static long keyring_read(const struct key *keyring,
}
/*
* allocate a keyring and link into the destination keyring
* Allocate a keyring and link into the destination keyring.
*/
struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
const struct cred *cred, unsigned long flags,
......@@ -258,16 +262,40 @@ struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
return keyring;
}
/*
* 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 rely on RCU to prevent the keyring lists from disappearing on us
* - we return -EAGAIN if we didn't find any matching key
* - we return -ENOKEY if we only found negative matching keys
* - we propagate the possession attribute from the keyring ref to the key ref
/**
* keyring_search_aux - Search a keyring tree for a key matching some criteria
* @keyring_ref: A pointer to the keyring with possession indicator.
* @cred: The credentials to use for permissions checks.
* @type: The type of key to search for.
* @description: Parameter for @match.
* @match: Function to rule on whether or not a key is the one required.
*
* 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 is 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,
const struct cred *cred,
......@@ -431,13 +459,14 @@ key_ref_t keyring_search_aux(key_ref_t keyring_ref,
return key_ref;
}
/*
* 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
/**
* 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.
*/
key_ref_t keyring_search(key_ref_t keyring,
struct key_type *type,
......@@ -449,13 +478,22 @@ key_ref_t keyring_search(key_ref_t keyring,
return keyring_search_aux(keyring, current->cred,
type, description, type->match);
}
EXPORT_SYMBOL(keyring_search);
/*
* search the given keyring only (no recursion)
* - keyring must be locked by caller
* - caller must guarantee that the keyring is a keyring
* Search the given keyring only (no recursion).
*
* The caller must guarantee that the keyring is a keyring and that the
* permission is granted to search the keyring as no check is made here.
*
* RCU is used to make it unnecessary to lock the keyring key list here.
*
* Returns a pointer to the found key with usage count incremented if
* successful and returns -ENOKEY if not found. Revoked keys and keys not
* providing the requested permission are skipped over.
*
* If successful, the possession indicator is propagated from the keyring ref
* to the returned key reference.
*/
key_ref_t __keyring_search_one(key_ref_t keyring_ref,
const struct key_type *ktype,
......@@ -498,9 +536,15 @@ key_ref_t __keyring_search_one(key_ref_t keyring_ref,
}
/*
* find a keyring with the specified name
* - all named keyrings are searched
* - normally only finds keyrings with search permission for the current process
* 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)
{
......@@ -551,10 +595,11 @@ struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
}
/*
* 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
* 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)
{
......@@ -637,7 +682,7 @@ static int keyring_detect_cycle(struct key *A, struct key *B)
}
/*
* dispose of a keyring list after the RCU grace period, freeing the unlinked
* Dispose of a keyring list after the RCU grace period, freeing the unlinked
* key
*/
static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
......@@ -651,7 +696,7 @@ static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
}
/*
* preallocate memory so that a key can be linked into to a keyring
* Preallocate memory so that a key can be linked into to a keyring.
*/
int __key_link_begin(struct key *keyring, const struct key_type *type,
const char *description,
......@@ -768,10 +813,10 @@ int __key_link_begin(struct key *keyring, const struct key_type *type,
}
/*
* 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
* 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)
{
......@@ -783,9 +828,12 @@ int __key_link_check_live_key(struct key *keyring, struct key *key)
}
/*
* link a key into to a keyring
* - must be called with __key_link_begin() having being called
* - discard already extant link to matching key if there is one
* Link a key into to a keyring.
*
* Must be called with __key_link_begin() having being called. Discards any
* already extant link to matching key if there is one, so that each keyring
* holds at most one link to any given key of a particular type+description
* combination.
*/
void __key_link(struct key *keyring, struct key *key,
struct keyring_list **_prealloc)
......@@ -828,8 +876,9 @@ void __key_link(struct key *keyring, struct key *key,
}
/*
* finish linking a key into to a keyring
* - must be called with __key_link_begin() having being called
* 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, struct key_type *type,
struct keyring_list *prealloc)
......@@ -850,8 +899,25 @@ void __key_link_end(struct key *keyring, struct key_type *type,
up_write(&keyring->sem);
}
/*
* link a key to a keyring
/**
* 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)
{
......@@ -871,11 +937,24 @@ int key_link(struct key *keyring, struct key *key)
return ret;
}
EXPORT_SYMBOL(key_link);
/*
* unlink the first link to a key from a keyring
/**
* 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)
{
......@@ -944,12 +1023,11 @@ int key_unlink(struct key *keyring, struct key *key)
up_write(&keyring->sem);
goto error;
}
EXPORT_SYMBOL(key_unlink);
/*
* dispose of a keyring list after the RCU grace period, releasing the keys it
* links to
* Dispose of a keyring list after the RCU grace period, releasing the keys it
* links to.
*/
static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
{
......@@ -964,9 +1042,13 @@ static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
kfree(klist);
}
/*
* clear the specified process keyring
* - implements keyctl(KEYCTL_CLEAR)
/**
* 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)
{
......@@ -999,12 +1081,12 @@ int keyring_clear(struct key *keyring)
return ret;
}
EXPORT_SYMBOL(keyring_clear);
/*
* dispose of the links from a revoked keyring
* - called with the key sem write-locked
* Dispose of the links from a revoked keyring.
*
* This is called with the key sem write-locked.
*/
static void keyring_revoke(struct key *keyring)
{
......@@ -1022,7 +1104,7 @@ static void keyring_revoke(struct key *keyring)
}
/*
* Determine whether a key is dead
* Determine whether a key is dead.
*/
static bool key_is_dead(struct key *key, time_t limit)
{
......@@ -1031,7 +1113,12 @@ static bool key_is_dead(struct key *key, time_t limit)
}
/*
* Collect garbage from the contents of a keyring
* Collect garbage from the contents of a keyring, replacing the old list with
* a new one with the pointers all shuffled down.
*
* Dead keys are classed as oned that are flagged as being dead or are revoked,
* expired or negative keys that were revoked or expired before the specified
* limit.
*/
void keyring_gc(struct key *keyring, time_t limit)
{
......
security/keys/permission.c
浏览文件 @ 973c9f4f
/* permission.c: key permission determination
/* Key permission checking
*
* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -15,15 +15,17 @@
/**
* key_task_permission - Check a key can be used
* @key_ref: The key to check
* @cred: The credentials to use
* @perm: The permissions to check for
* @key_ref: The key to check.
* @cred: The credentials to use.
* @perm: The permissions to check for.
*
* Check to see whether permission is granted to use a key in the desired way,
* but permit the security modules to override.
*
* The caller must hold either a ref on cred or must hold the RCU readlock or a
* spinlock.
* The caller must hold either a ref on cred or must hold the RCU readlock.
*
* Returns 0 if successful, -EACCES if access is denied based on the
* permissions bits or the LSM check.
*/
int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
key_perm_t perm)
......@@ -79,11 +81,15 @@ int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
/* let LSM be the final arbiter */
return security_key_permission(key_ref, cred, perm);
}
EXPORT_SYMBOL(key_task_permission);
/*
* validate a key
/**
* key_validate - Validate a key.
* @key: The key to be validated.
*
* Check that a key is valid, returning 0 if the key is okay, -EKEYREVOKED if
* the key's type has been removed or if the key has been revoked or
* -EKEYEXPIRED if the key has expired.
*/
int key_validate(struct key *key)
{
......@@ -109,5 +115,4 @@ int key_validate(struct key *key)
error:
return ret;
}
EXPORT_SYMBOL(key_validate);
security/keys/proc.c
浏览文件 @ 973c9f4f
/* proc.c: proc files for key database enumeration
/* procfs files for key database enumeration
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -61,7 +61,7 @@ static const struct file_operations proc_key_users_fops = {
};
/*
* declare the /proc files
* Declare the /proc files.
*/
static int __init key_proc_init(void)
{
......@@ -83,7 +83,8 @@ static int __init key_proc_init(void)
__initcall(key_proc_init);
/*
* implement "/proc/keys" to provides a list of the keys on the system
* Implement "/proc/keys" to provide a list of the keys on the system that
* grant View permission to the caller.
*/
#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
......@@ -291,7 +292,8 @@ static struct rb_node *key_user_first(struct rb_root *r)
}
/*
* implement "/proc/key-users" to provides a list of the key users
* Implement "/proc/key-users" to provides a list of the key users and their
* quotas.
*/
static int proc_key_users_open(struct inode *inode, struct file *file)
{
......
security/keys/process_keys.c
浏览文件 @ 973c9f4f
/* Management of a process's keyrings
/* Manage a process's keyrings
*
* Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -21,13 +21,13 @@
#include <asm/uaccess.h>
#include "internal.h"
/* session keyring create vs join semaphore */
/* Session keyring create vs join semaphore */
static DEFINE_MUTEX(key_session_mutex);
/* user keyring creation semaphore */
/* User keyring creation semaphore */
static DEFINE_MUTEX(key_user_keyring_mutex);
/* the root user's tracking struct */
/* The root user's tracking struct */
struct key_user root_key_user = {
.usage = ATOMIC_INIT(3),
.cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock),
......@@ -39,7 +39,7 @@ struct key_user root_key_user = {
};
/*
* install user and user session keyrings for a particular UID
* Install the user and user session keyrings for the current process's UID.
*/
int install_user_keyrings(void)
{
......@@ -121,7 +121,8 @@ int install_user_keyrings(void)
}
/*
* install a fresh thread keyring directly to new credentials
* Install a fresh thread keyring directly to new credentials. This keyring is
* allowed to overrun the quota.
*/
int install_thread_keyring_to_cred(struct cred *new)
{
......@@ -137,7 +138,7 @@ int install_thread_keyring_to_cred(struct cred *new)
}
/*
* install a fresh thread keyring, discarding the old one
* Install a fresh thread keyring, discarding the old one.
*/
static int install_thread_keyring(void)
{
......@@ -160,9 +161,10 @@ static int install_thread_keyring(void)
}
/*
* install a process keyring directly to a credentials struct
* - returns -EEXIST if there was already a process keyring, 0 if one installed,
* and other -ve on any other error
* Install a process keyring directly to a credentials struct.
*
* Returns -EEXIST if there was already a process keyring, 0 if one installed,
* and other value on any other error
*/
int install_process_keyring_to_cred(struct cred *new)
{
......@@ -191,8 +193,11 @@ int install_process_keyring_to_cred(struct cred *new)
}
/*
* make sure a process keyring is installed
* - we
* Make sure a process keyring is installed for the current process. The
* existing process keyring is not replaced.
*
* Returns 0 if there is a process keyring by the end of this function, some
* error otherwise.
*/
static int install_process_keyring(void)
{
......@@ -213,7 +218,7 @@ static int install_process_keyring(void)
}
/*
* install a session keyring directly to a credentials struct
* Install a session keyring directly to a credentials struct.
*/
int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
{
......@@ -253,8 +258,8 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
}
/*
* install a session keyring, discarding the old one
* - if a keyring is not supplied, an empty one is invented
* Install a session keyring, discarding the old one. If a keyring is not
* supplied, an empty one is invented.
*/
static int install_session_keyring(struct key *keyring)
{
......@@ -275,7 +280,7 @@ static int install_session_keyring(struct key *keyring)
}
/*
* the filesystem user ID changed
* Handle the fsuid changing.
*/
void key_fsuid_changed(struct task_struct *tsk)
{
......@@ -289,7 +294,7 @@ void key_fsuid_changed(struct task_struct *tsk)
}
/*
* the filesystem group ID changed
* Handle the fsgid changing.
*/
void key_fsgid_changed(struct task_struct *tsk)
{
......@@ -303,11 +308,25 @@ void key_fsgid_changed(struct task_struct *tsk)
}
/*
* search only my process keyrings for the first matching key
* - we use the supplied match function to see if the description (or other
* feature of interest) matches
* - we return -EAGAIN if we didn't find any matching key
* - we return -ENOKEY if we found only negative matching keys
* Search the process keyrings attached to the supplied cred for the first
* matching key.
*
* The search criteria are the type and the match function. The description is
* given to the match function as a parameter, but doesn't otherwise influence
* the search. Typically the match function will compare the description
* parameter to the key's description.
*
* This can only search keyrings that grant Search permission to the supplied
* credentials. Keyrings linked to searched keyrings will also be searched if
* they grant Search permission too. Keys can only be found if they grant
* Search permission to the credentials.
*
* Returns a pointer to the key with the key usage count incremented if
* successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
* matched negative keys.
*
* In the case of a successful return, the possession attribute is set on the
* returned key reference.
*/
key_ref_t search_my_process_keyrings(struct key_type *type,
const void *description,
......@@ -423,11 +442,12 @@ key_ref_t search_my_process_keyrings(struct key_type *type,
}
/*
* search the process keyrings for the first matching key
* - we use the supplied match function to see if the description (or other
* feature of interest) matches
* - we return -EAGAIN if we didn't find any matching key
* - we return -ENOKEY if we found only negative matching keys
* Search the process keyrings attached to the supplied cred for the first
* matching key in the manner of search_my_process_keyrings(), but also search
* the keys attached to the assumed authorisation key using its credentials if
* one is available.
*
* Return same as search_my_process_keyrings().
*/
key_ref_t search_process_keyrings(struct key_type *type,
const void *description,
......@@ -485,7 +505,7 @@ key_ref_t search_process_keyrings(struct key_type *type,
}
/*
* see if the key we're looking at is the target key
* See if the key we're looking at is the target key.
*/
int lookup_user_key_possessed(const struct key *key, const void *target)
{
......@@ -493,9 +513,22 @@ int lookup_user_key_possessed(const struct key *key, const void *target)
}
/*
* lookup a key given a key ID from userspace with a given permissions mask
* - don't create special keyrings unless so requested
* - partially constructed keys aren't found unless requested
* Look up a key ID given us by userspace with a given permissions mask to get
* the key it refers to.
*
* Flags can be passed to request that special keyrings be created if referred
* to directly, to permit partially constructed keys to be found and to skip
* validity and permission checks on the found key.
*
* Returns a pointer to the key with an incremented usage count if successful;
* -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
* to a key or the best found key was a negative key; -EKEYREVOKED or
* -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
* found key doesn't grant the requested permit or the LSM denied access to it;
* or -ENOMEM if a special keyring couldn't be created.
*
* In the case of a successful return, the possession attribute is set on the
* returned key reference.
*/
key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
key_perm_t perm)
......@@ -703,10 +736,15 @@ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
}
/*
* join the named keyring as the session keyring if possible, or attempt to
* create a new one of that name if not
* - if the name is NULL, an empty anonymous keyring is installed instead
* - named session keyring joining is done with a semaphore held
* Join the named keyring as the session keyring if possible else attempt to
* create a new one of that name and join that.
*
* If the name is NULL, an empty anonymous keyring will be installed as the
* session keyring.
*
* Named session keyrings are joined with a semaphore held to prevent the
* keyrings from going away whilst the attempt is made to going them and also
* to prevent a race in creating compatible session keyrings.
*/
long join_session_keyring(const char *name)
{
......@@ -778,8 +816,8 @@ long join_session_keyring(const char *name)
}
/*
* Replace a process's session keyring when that process resumes userspace on
* behalf of one of its children
* Replace a process's session keyring on behalf of one of its children when
* the target process is about to resume userspace execution.
*/
void key_replace_session_keyring(void)
{
......
security/keys/request_key.c
浏览文件 @ 973c9f4f
......@@ -39,8 +39,14 @@ static int key_wait_bit_intr(void *flags)
return signal_pending(current) ? -ERESTARTSYS : 0;
}
/*
* call to complete the construction of a key
/**
* complete_request_key - Complete the construction of a key.
* @cons: The key construction record.
* @error: The success or failute of the construction.
*
* Complete the attempt to construct a key. The key will be negated
* if an error is indicated. The authorisation key will be revoked
* unconditionally.
*/
void complete_request_key(struct key_construction *cons, int error)
{
......@@ -58,23 +64,33 @@ void complete_request_key(struct key_construction *cons, int error)
}
EXPORT_SYMBOL(complete_request_key);
/*
* Initialise a usermode helper that is going to have a specific session
* keyring.
*
* This is called in context of freshly forked kthread before kernel_execve(),
* so we can simply install the desired session_keyring at this point.
*/
static int umh_keys_init(struct subprocess_info *info)
{
struct cred *cred = (struct cred*)current_cred();
struct key *keyring = info->data;
/*
* This is called in context of freshly forked kthread before
* kernel_execve(), we can just change our ->session_keyring.
*/
return install_session_keyring_to_cred(cred, keyring);
}
/*
* Clean up a usermode helper with session keyring.
*/
static void umh_keys_cleanup(struct subprocess_info *info)
{
struct key *keyring = info->data;
key_put(keyring);
}
/*
* Call a usermode helper with a specific session keyring.
*/
static int call_usermodehelper_keys(char *path, char **argv, char **envp,
struct key *session_keyring, enum umh_wait wait)
{
......@@ -91,7 +107,7 @@ static int call_usermodehelper_keys(char *path, char **argv, char **envp,
}
/*
* request userspace finish the construction of a key
* Request userspace finish the construction of a key
* - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
*/
static int call_sbin_request_key(struct key_construction *cons,
......@@ -198,8 +214,9 @@ static int call_sbin_request_key(struct key_construction *cons,
}
/*
* call out to userspace for key construction
* - we ignore program failure and go on key status instead
* Call out to userspace for key construction.
*
* Program failure is ignored in favour of key status.
*/
static int construct_key(struct key *key, const void *callout_info,
size_t callout_len, void *aux,
......@@ -246,9 +263,10 @@ static int construct_key(struct key *key, const void *callout_info,
}
/*
* get the appropriate destination keyring for the request
* - we return whatever keyring we select with an extra reference upon it which
* the caller must release
* Get the appropriate destination keyring for the request.
*
* The keyring selected is returned with an extra reference upon it which the
* caller must release.
*/
static void construct_get_dest_keyring(struct key **_dest_keyring)
{
......@@ -321,9 +339,11 @@ static void construct_get_dest_keyring(struct key **_dest_keyring)
}
/*
* allocate a new key in under-construction state and attempt to link it in to
* the requested place
* - may return a key that's already under construction instead
* Allocate a new key in under-construction state and attempt to link it in to
* the requested keyring.
*
* May return a key that's already under construction instead if there was a
* race between two thread calling request_key().
*/
static int construct_alloc_key(struct key_type *type,
const char *description,
......@@ -414,7 +434,7 @@ static int construct_alloc_key(struct key_type *type,
}
/*
* commence key construction
* Commence key construction.
*/
static struct key *construct_key_and_link(struct key_type *type,
const char *description,
......@@ -465,12 +485,32 @@ static struct key *construct_key_and_link(struct key_type *type,
return ERR_PTR(ret);
}
/*
* request a key
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
* - cache the key in an appropriate keyring
/**
* request_key_and_link - Request a key and cache it in a keyring.
* @type: The type of key we want.
* @description: The searchable description of the key.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
* @callout_len: The length of callout_info.
* @aux: Auxiliary data for the upcall.
* @dest_keyring: Where to cache the key.
* @flags: Flags to key_alloc().
*
* A key matching the specified criteria is searched for in the process's
* keyrings and returned with its usage count incremented if found. Otherwise,
* if callout_info is not NULL, a key will be allocated and some service
* (probably in userspace) will be asked to instantiate it.
*
* If successfully found or created, the key will be linked to the destination
* keyring if one is provided.
*
* Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
* or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
* found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
* if insufficient key quota was available to create a new key; or -ENOMEM if
* insufficient memory was available.
*
* If the returned key was created, then it may still be under construction,
* and wait_for_key_construction() should be used to wait for that to complete.
*/
struct key *request_key_and_link(struct key_type *type,
const char *description,
......@@ -524,8 +564,16 @@ struct key *request_key_and_link(struct key_type *type,
return key;
}
/*
* wait for construction of a key to complete
/**
* wait_for_key_construction - Wait for construction of a key to complete
* @key: The key being waited for.
* @intr: Whether to wait interruptibly.
*
* Wait for a key to finish being constructed.
*
* Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
* if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
* revoked or expired.
*/
int wait_for_key_construction(struct key *key, bool intr)
{
......@@ -542,12 +590,19 @@ int wait_for_key_construction(struct key *key, bool intr)
}
EXPORT_SYMBOL(wait_for_key_construction);
/*
* request a key
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
* - waits uninterruptible for creation to complete
/**
* request_key - Request a key and wait for construction
* @type: Type of key.
* @description: The searchable description of the key.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
*
* As for request_key_and_link() except that it does not add the returned key
* to a keyring if found, new keys are always allocated in the user's quota,
* the callout_info must be a NUL-terminated string and no auxiliary data can
* be passed.
*
* Furthermore, it then works as wait_for_key_construction() to wait for the
* completion of keys undergoing construction with a non-interruptible wait.
*/
struct key *request_key(struct key_type *type,
const char *description,
......@@ -572,12 +627,19 @@ struct key *request_key(struct key_type *type,
}
EXPORT_SYMBOL(request_key);
/*
* request a key with auxiliary data for the upcaller
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
* - waits uninterruptible for creation to complete
/**
* request_key_with_auxdata - Request a key with auxiliary data for the upcaller
* @type: The type of key we want.
* @description: The searchable description of the key.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
* @callout_len: The length of callout_info.
* @aux: Auxiliary data for the upcall.
*
* As for request_key_and_link() except that it does not add the returned key
* to a keyring if found and new keys are always allocated in the user's quota.
*
* Furthermore, it then works as wait_for_key_construction() to wait for the
* completion of keys undergoing construction with a non-interruptible wait.
*/
struct key *request_key_with_auxdata(struct key_type *type,
const char *description,
......@@ -602,10 +664,18 @@ struct key *request_key_with_auxdata(struct key_type *type,
EXPORT_SYMBOL(request_key_with_auxdata);
/*
* request a key (allow async construction)
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
* request_key_async - Request a key (allow async construction)
* @type: Type of key.
* @description: The searchable description of the key.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
* @callout_len: The length of callout_info.
*
* As for request_key_and_link() except that it does not add the returned key
* to a keyring if found, new keys are always allocated in the user's quota and
* no auxiliary data can be passed.
*
* The caller should call wait_for_key_construction() to wait for the
* completion of the returned key if it is still undergoing construction.
*/
struct key *request_key_async(struct key_type *type,
const char *description,
......@@ -620,9 +690,17 @@ EXPORT_SYMBOL(request_key_async);
/*
* request a key with auxiliary data for the upcaller (allow async construction)
* - search the process's keyrings
* - check the list of keys being created or updated
* - call out to userspace for a key if supplementary info was provided
* @type: Type of key.
* @description: The searchable description of the key.
* @callout_info: The data to pass to the instantiation upcall (or NULL).
* @callout_len: The length of callout_info.
* @aux: Auxiliary data for the upcall.
*
* As for request_key_and_link() except that it does not add the returned key
* to a keyring if found and new keys are always allocated in the user's quota.
*
* The caller should call wait_for_key_construction() to wait for the
* completion of the returned key if it is still undergoing construction.
*/
struct key *request_key_async_with_auxdata(struct key_type *type,
const char *description,
......
security/keys/request_key_auth.c
浏览文件 @ 973c9f4f
/* request_key_auth.c: request key authorisation controlling key def
/* Request key authorisation token key definition.
*
* Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
......@@ -26,7 +26,7 @@ static void request_key_auth_destroy(struct key *);
static long request_key_auth_read(const struct key *, char __user *, size_t);
/*
* the request-key authorisation key type definition
* The request-key authorisation key type definition.
*/
struct key_type key_type_request_key_auth = {
.name = ".request_key_auth",
......@@ -39,7 +39,7 @@ struct key_type key_type_request_key_auth = {
};
/*
* instantiate a request-key authorisation key
* Instantiate a request-key authorisation key.
*/
static int request_key_auth_instantiate(struct key *key,
const void *data,
......@@ -50,7 +50,7 @@ static int request_key_auth_instantiate(struct key *key,
}
/*
* reading a request-key authorisation key retrieves the callout information
* Describe an authorisation token.
*/
static void request_key_auth_describe(const struct key *key,
struct seq_file *m)
......@@ -63,7 +63,7 @@ static void request_key_auth_describe(const struct key *key,
}
/*
* read the callout_info data
* Read the callout_info data (retrieves the callout information).
* - the key's semaphore is read-locked
*/
static long request_key_auth_read(const struct key *key,
......@@ -89,8 +89,9 @@ static long request_key_auth_read(const struct key *key,
}
/*
* handle revocation of an authorisation token key
* - called with the key sem write-locked
* Handle revocation of an authorisation token key.
*
* Called with the key sem write-locked.
*/
static void request_key_auth_revoke(struct key *key)
{
......@@ -105,7 +106,7 @@ static void request_key_auth_revoke(struct key *key)
}
/*
* destroy an instantiation authorisation token key
* Destroy an instantiation authorisation token key.
*/
static void request_key_auth_destroy(struct key *key)
{
......@@ -125,8 +126,8 @@ static void request_key_auth_destroy(struct key *key)
}
/*
* create an authorisation token for /sbin/request-key or whoever to gain
* access to the caller's security data
* Create an authorisation token for /sbin/request-key or whoever to gain
* access to the caller's security data.
*/
struct key *request_key_auth_new(struct key *target, const void *callout_info,
size_t callout_len, struct key *dest_keyring)
......@@ -220,7 +221,7 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
}
/*
* see if an authorisation key is associated with a particular key
* See if an authorisation key is associated with a particular key.
*/
static int key_get_instantiation_authkey_match(const struct key *key,
const void *_id)
......@@ -232,11 +233,8 @@ static int key_get_instantiation_authkey_match(const struct key *key,
}
/*
* get the authorisation key for instantiation of a specific key if attached to
* the current process's keyrings
* - this key is inserted into a keyring and that is set as /sbin/request-key's
* session keyring
* - a target_id of zero specifies any valid token
* Search the current process's keyrings for the authorisation key for
* instantiation of a key.
*/
struct key *key_get_instantiation_authkey(key_serial_t target_id)
{
......
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