Since commit b2a4df200d ("KEYS: Expand the capacity of a keyring")
iterate_over_keyring() is never used, so can be removed.
And commit b5f545c880 ("[PATCH] keys: Permit running process to instantiate keys")
left behind keyring_search_instkey().
Fixes: b2a4df200d ("KEYS: Expand the capacity of a keyring")
Fixes: b5f545c880 ("[PATCH] keys: Permit running process to instantiate keys")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
In preparation for the patch that introduces the bpf_lookup_user_key() eBPF
kfunc, move KEY_LOOKUP_ definitions to include/linux/key.h, to be able to
validate the kfunc parameters. Add them to enum key_lookup_flag, so that
all the current ones and the ones defined in the future are automatically
exported through BTF and available to eBPF programs.
Also, add KEY_LOOKUP_ALL to the enum, with the logical OR of currently
defined flags as value, to facilitate checking whether a variable contains
only those flags.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20220920075951.929132-7-roberto.sassu@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that import_iovec handles compat iovecs, the native version of
keyctl_instantiate_key_iov can be used for the compat case as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'notifications-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull notification queue from David Howells:
"This adds a general notification queue concept and adds an event
source for keys/keyrings, such as linking and unlinking keys and
changing their attributes.
Thanks to Debarshi Ray, we do have a pull request to use this to fix a
problem with gnome-online-accounts - as mentioned last time:
https://gitlab.gnome.org/GNOME/gnome-online-accounts/merge_requests/47
Without this, g-o-a has to constantly poll a keyring-based kerberos
cache to find out if kinit has changed anything.
[ There are other notification pending: mount/sb fsinfo notifications
for libmount that Karel Zak and Ian Kent have been working on, and
Christian Brauner would like to use them in lxc, but let's see how
this one works first ]
LSM hooks are included:
- A set of hooks are provided that allow an LSM to rule on whether or
not a watch may be set. Each of these hooks takes a different
"watched object" parameter, so they're not really shareable. The
LSM should use current's credentials. [Wanted by SELinux & Smack]
- A hook is provided to allow an LSM to rule on whether or not a
particular message may be posted to a particular queue. This is
given the credentials from the event generator (which may be the
system) and the watch setter. [Wanted by Smack]
I've provided SELinux and Smack with implementations of some of these
hooks.
WHY
===
Key/keyring notifications are desirable because if you have your
kerberos tickets in a file/directory, your Gnome desktop will monitor
that using something like fanotify and tell you if your credentials
cache changes.
However, we also have the ability to cache your kerberos tickets in
the session, user or persistent keyring so that it isn't left around
on disk across a reboot or logout. Keyrings, however, cannot currently
be monitored asynchronously, so the desktop has to poll for it - not
so good on a laptop. This facility will allow the desktop to avoid the
need to poll.
DESIGN DECISIONS
================
- The notification queue is built on top of a standard pipe. Messages
are effectively spliced in. The pipe is opened with a special flag:
pipe2(fds, O_NOTIFICATION_PIPE);
The special flag has the same value as O_EXCL (which doesn't seem
like it will ever be applicable in this context)[?]. It is given up
front to make it a lot easier to prohibit splice&co from accessing
the pipe.
[?] Should this be done some other way? I'd rather not use up a new
O_* flag if I can avoid it - should I add a pipe3() system call
instead?
The pipe is then configured::
ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, queue_depth);
ioctl(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter);
Messages are then read out of the pipe using read().
- It should be possible to allow write() to insert data into the
notification pipes too, but this is currently disabled as the
kernel has to be able to insert messages into the pipe *without*
holding pipe->mutex and the code to make this work needs careful
auditing.
- sendfile(), splice() and vmsplice() are disabled on notification
pipes because of the pipe->mutex issue and also because they
sometimes want to revert what they just did - but one or more
notification messages might've been interleaved in the ring.
- The kernel inserts messages with the wait queue spinlock held. This
means that pipe_read() and pipe_write() have to take the spinlock
to update the queue pointers.
- Records in the buffer are binary, typed and have a length so that
they can be of varying size.
This allows multiple heterogeneous sources to share a common
buffer; there are 16 million types available, of which I've used
just a few, so there is scope for others to be used. Tags may be
specified when a watchpoint is created to help distinguish the
sources.
- Records are filterable as types have up to 256 subtypes that can be
individually filtered. Other filtration is also available.
- Notification pipes don't interfere with each other; each may be
bound to a different set of watches. Any particular notification
will be copied to all the queues that are currently watching for it
- and only those that are watching for it.
- When recording a notification, the kernel will not sleep, but will
rather mark a queue as having lost a message if there's
insufficient space. read() will fabricate a loss notification
message at an appropriate point later.
- The notification pipe is created and then watchpoints are attached
to it, using one of:
keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fds[1], 0x01);
watch_mount(AT_FDCWD, "/", 0, fd, 0x02);
watch_sb(AT_FDCWD, "/mnt", 0, fd, 0x03);
where in both cases, fd indicates the queue and the number after is
a tag between 0 and 255.
- Watches are removed if either the notification pipe is destroyed or
the watched object is destroyed. In the latter case, a message will
be generated indicating the enforced watch removal.
Things I want to avoid:
- Introducing features that make the core VFS dependent on the
network stack or networking namespaces (ie. usage of netlink).
- Dumping all this stuff into dmesg and having a daemon that sits
there parsing the output and distributing it as this then puts the
responsibility for security into userspace and makes handling
namespaces tricky. Further, dmesg might not exist or might be
inaccessible inside a container.
- Letting users see events they shouldn't be able to see.
TESTING AND MANPAGES
====================
- The keyutils tree has a pipe-watch branch that has keyctl commands
for making use of notifications. Proposed manual pages can also be
found on this branch, though a couple of them really need to go to
the main manpages repository instead.
If the kernel supports the watching of keys, then running "make
test" on that branch will cause the testing infrastructure to spawn
a monitoring process on the side that monitors a notifications pipe
for all the key/keyring changes induced by the tests and they'll
all be checked off to make sure they happened.
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git/log/?h=pipe-watch
- A test program is provided (samples/watch_queue/watch_test) that
can be used to monitor for keyrings, mount and superblock events.
Information on the notifications is simply logged to stdout"
* tag 'notifications-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
smack: Implement the watch_key and post_notification hooks
selinux: Implement the watch_key security hook
keys: Make the KEY_NEED_* perms an enum rather than a mask
pipe: Add notification lossage handling
pipe: Allow buffers to be marked read-whole-or-error for notifications
Add sample notification program
watch_queue: Add a key/keyring notification facility
security: Add hooks to rule on setting a watch
pipe: Add general notification queue support
pipe: Add O_NOTIFICATION_PIPE
security: Add a hook for the point of notification insertion
uapi: General notification queue definitions
For kvmalloc'ed data object that contains sensitive information like
cryptographic keys, we need to make sure that the buffer is always cleared
before freeing it. Using memset() alone for buffer clearing may not
provide certainty as the compiler may compile it away. To be sure, the
special memzero_explicit() has to be used.
This patch introduces a new kvfree_sensitive() for freeing those sensitive
data objects allocated by kvmalloc(). The relevant places where
kvfree_sensitive() can be used are modified to use it.
Fixes: 4f0882491a ("KEYS: Avoid false positive ENOMEM error on key read")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Link: http://lkml.kernel.org/r/20200407200318.11711-1-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the meaning of combining the KEY_NEED_* constants is undefined, make
it so that you can't do that by turning them into an enum.
The enum is also given some extra values to represent special
circumstances, such as:
(1) The '0' value is reserved and causes a warning to trap the parameter
being unset.
(2) The key is to be unlinked and we require no permissions on it, only
the keyring, (this replaces the KEY_LOOKUP_FOR_UNLINK flag).
(3) An override due to CAP_SYS_ADMIN.
(4) An override due to an instantiation token being present.
(5) The permissions check is being deferred to later key_permission()
calls.
The extra values give the opportunity for LSMs to audit these situations.
[Note: This really needs overhauling so that lookup_user_key() tells
key_task_permission() and the LSM what operation is being done and leaves
it to those functions to decide how to map that onto the available
permits. However, I don't really want to make these change in the middle
of the notifications patchset.]
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
cc: Paul Moore <paul@paul-moore.com>
cc: Stephen Smalley <stephen.smalley.work@gmail.com>
cc: Casey Schaufler <casey@schaufler-ca.com>
cc: keyrings@vger.kernel.org
cc: selinux@vger.kernel.org
Add a key/keyring change notification facility whereby notifications about
changes in key and keyring content and attributes can be received.
Firstly, an event queue needs to be created:
pipe2(fds, O_NOTIFICATION_PIPE);
ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, 256);
then a notification can be set up to report notifications via that queue:
struct watch_notification_filter filter = {
.nr_filters = 1,
.filters = {
[0] = {
.type = WATCH_TYPE_KEY_NOTIFY,
.subtype_filter[0] = UINT_MAX,
},
},
};
ioctl(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter);
keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fds[1], 0x01);
After that, records will be placed into the queue when events occur in
which keys are changed in some way. Records are of the following format:
struct key_notification {
struct watch_notification watch;
__u32 key_id;
__u32 aux;
} *n;
Where:
n->watch.type will be WATCH_TYPE_KEY_NOTIFY.
n->watch.subtype will indicate the type of event, such as
NOTIFY_KEY_REVOKED.
n->watch.info & WATCH_INFO_LENGTH will indicate the length of the
record.
n->watch.info & WATCH_INFO_ID will be the second argument to
keyctl_watch_key(), shifted.
n->key will be the ID of the affected key.
n->aux will hold subtype-dependent information, such as the key
being linked into the keyring specified by n->key in the case of
NOTIFY_KEY_LINKED.
Note that it is permissible for event records to be of variable length -
or, at least, the length may be dependent on the subtype. Note also that
the queue can be shared between multiple notifications of various types.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
By allocating a kernel buffer with a user-supplied buffer length, it
is possible that a false positive ENOMEM error may be returned because
the user-supplied length is just too large even if the system do have
enough memory to hold the actual key data.
Moreover, if the buffer length is larger than the maximum amount of
memory that can be returned by kmalloc() (2^(MAX_ORDER-1) number of
pages), a warning message will also be printed.
To reduce this possibility, we set a threshold (PAGE_SIZE) over which we
do check the actual key length first before allocating a buffer of the
right size to hold it. The threshold is arbitrary, it is just used to
trigger a buffer length check. It does not limit the actual key length
as long as there is enough memory to satisfy the memory request.
To further avoid large buffer allocation failure due to page
fragmentation, kvmalloc() is used to allocate the buffer so that vmapped
pages can be used when there is not a large enough contiguous set of
pages available for allocation.
In the extremely unlikely scenario that the key keeps on being changed
and made longer (still <= buflen) in between 2 __keyctl_read_key()
calls, the __keyctl_read_key() calling loop in keyctl_read_key() may
have to be iterated a large number of times, but definitely not infinite.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
KEYS_COMPAT now always takes the value of COMPAT && KEYS. But the
security/keys/ directory is only compiled if KEYS is enabled, so in
practice KEYS_COMPAT is the same as COMPAT. Therefore, remove the
unnecessary KEYS_COMPAT and just use COMPAT directly.
(Also remove an outdated comment from compat.c.)
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull keyring ACL support from David Howells:
"This changes the permissions model used by keys and keyrings to be
based on an internal ACL by the following means:
- Replace the permissions mask internally with an ACL that contains a
list of ACEs, each with a specific subject with a permissions mask.
Potted default ACLs are available for new keys and keyrings.
ACE subjects can be macroised to indicate the UID and GID specified
on the key (which remain). Future commits will be able to add
additional subject types, such as specific UIDs or domain
tags/namespaces.
Also split a number of permissions to give finer control. Examples
include splitting the revocation permit from the change-attributes
permit, thereby allowing someone to be granted permission to revoke
a key without allowing them to change the owner; also the ability
to join a keyring is split from the ability to link to it, thereby
stopping a process accessing a keyring by joining it and thus
acquiring use of possessor permits.
- Provide a keyctl to allow the granting or denial of one or more
permits to a specific subject. Direct access to the ACL is not
granted, and the ACL cannot be viewed"
* tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
keys: Provide KEYCTL_GRANT_PERMISSION
keys: Replace uid/gid/perm permissions checking with an ACL
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Merge tag 'keys-namespace-20190627' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull keyring namespacing from David Howells:
"These patches help make keys and keyrings more namespace aware.
Firstly some miscellaneous patches to make the process easier:
- Simplify key index_key handling so that the word-sized chunks
assoc_array requires don't have to be shifted about, making it
easier to add more bits into the key.
- Cache the hash value in the key so that we don't have to calculate
on every key we examine during a search (it involves a bunch of
multiplications).
- Allow keying_search() to search non-recursively.
Then the main patches:
- Make it so that keyring names are per-user_namespace from the point
of view of KEYCTL_JOIN_SESSION_KEYRING so that they're not
accessible cross-user_namespace.
keyctl_capabilities() shows KEYCTL_CAPS1_NS_KEYRING_NAME for this.
- Move the user and user-session keyrings to the user_namespace
rather than the user_struct. This prevents them propagating
directly across user_namespaces boundaries (ie. the KEY_SPEC_*
flags will only pick from the current user_namespace).
- Make it possible to include the target namespace in which the key
shall operate in the index_key. This will allow the possibility of
multiple keys with the same description, but different target
domains to be held in the same keyring.
keyctl_capabilities() shows KEYCTL_CAPS1_NS_KEY_TAG for this.
- Make it so that keys are implicitly invalidated by removal of a
domain tag, causing them to be garbage collected.
- Institute a network namespace domain tag that allows keys to be
differentiated by the network namespace in which they operate. New
keys that are of a type marked 'KEY_TYPE_NET_DOMAIN' are assigned
the network domain in force when they are created.
- Make it so that the desired network namespace can be handed down
into the request_key() mechanism. This allows AFS, NFS, etc. to
request keys specific to the network namespace of the superblock.
This also means that the keys in the DNS record cache are
thenceforth namespaced, provided network filesystems pass the
appropriate network namespace down into dns_query().
For DNS, AFS and NFS are good, whilst CIFS and Ceph are not. Other
cache keyrings, such as idmapper keyrings, also need to set the
domain tag - for which they need access to the network namespace of
the superblock"
* tag 'keys-namespace-20190627' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
keys: Pass the network namespace into request_key mechanism
keys: Network namespace domain tag
keys: Garbage collect keys for which the domain has been removed
keys: Include target namespace in match criteria
keys: Move the user and user-session keyrings to the user_namespace
keys: Namespace keyring names
keys: Add a 'recurse' flag for keyring searches
keys: Cache the hash value to avoid lots of recalculation
keys: Simplify key description management
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Merge tag 'keys-request-20190626' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull request_key improvements from David Howells:
"These are all request_key()-related, including a fix and some improvements:
- Fix the lack of a Link permission check on a key found by
request_key(), thereby enabling request_key() to link keys that
don't grant this permission to the target keyring (which must still
grant Write permission).
Note that the key must be in the caller's keyrings already to be
found.
- Invalidate used request_key authentication keys rather than
revoking them, so that they get cleaned up immediately rather than
hanging around till the expiry time is passed.
- Move the RCU locks outwards from the keyring search functions so
that a request_key_rcu() can be provided. This can be called in RCU
mode, so it can't sleep and can't upcall - but it can be called
from LOOKUP_RCU pathwalk mode.
- Cache the latest positive result of request_key*() temporarily in
task_struct so that filesystems that make a lot of request_key()
calls during pathwalk can take advantage of it to avoid having to
redo the searching. This requires CONFIG_KEYS_REQUEST_CACHE=y.
It is assumed that the key just found is likely to be used multiple
times in each step in an RCU pathwalk, and is likely to be reused
for the next step too.
Note that the cleanup of the cache is done on TIF_NOTIFY_RESUME,
just before userspace resumes, and on exit"
* tag 'keys-request-20190626' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
keys: Kill off request_key_async{,_with_auxdata}
keys: Cache result of request_key*() temporarily in task_struct
keys: Provide request_key_rcu()
keys: Move the RCU locks outwards from the keyring search functions
keys: Invalidate used request_key authentication keys
keys: Fix request_key() lack of Link perm check on found key
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Merge tag 'keys-misc-20190619' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull misc keyring updates from David Howells:
"These are some miscellaneous keyrings fixes and improvements:
- Fix a bunch of warnings from sparse, including missing RCU bits and
kdoc-function argument mismatches
- Implement a keyctl to allow a key to be moved from one keyring to
another, with the option of prohibiting key replacement in the
destination keyring.
- Grant Link permission to possessors of request_key_auth tokens so
that upcall servicing daemons can more easily arrange things such
that only the necessary auth key is passed to the actual service
program, and not all the auth keys a daemon might possesss.
- Improvement in lookup_user_key().
- Implement a keyctl to allow keyrings subsystem capabilities to be
queried.
The keyutils next branch has commits to make available, document and
test the move-key and capabilities code:
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git/log
They're currently on the 'next' branch"
* tag 'keys-misc-20190619' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
keys: Add capability-checking keyctl function
keys: Reuse keyring_index_key::desc_len in lookup_user_key()
keys: Grant Link permission to possessers of request_key auth keys
keys: Add a keyctl to move a key between keyrings
keys: Hoist locking out of __key_link_begin()
keys: Break bits out of key_unlink()
keys: Change keyring_serialise_link_sem to a mutex
keys: sparse: Fix kdoc mismatches
keys: sparse: Fix incorrect RCU accesses
keys: sparse: Fix key_fs[ug]id_changed()
Provide a keyctl() operation to grant/remove permissions. The grant
operation, wrapped by libkeyutils, looks like:
int ret = keyctl_grant_permission(key_serial_t key,
enum key_ace_subject_type type,
unsigned int subject,
unsigned int perm);
Where key is the key to be modified, type and subject represent the subject
to which permission is to be granted (or removed) and perm is the set of
permissions to be granted. 0 is returned on success. SET_SECURITY
permission is required for this.
The subject type currently must be KEY_ACE_SUBJ_STANDARD for the moment
(other subject types will come along later).
For subject type KEY_ACE_SUBJ_STANDARD, the following subject values are
available:
KEY_ACE_POSSESSOR The possessor of the key
KEY_ACE_OWNER The owner of the key
KEY_ACE_GROUP The key's group
KEY_ACE_EVERYONE Everyone
perm lists the permissions to be granted:
KEY_ACE_VIEW Can view the key metadata
KEY_ACE_READ Can read the key content
KEY_ACE_WRITE Can update/modify the key content
KEY_ACE_SEARCH Can find the key by searching/requesting
KEY_ACE_LINK Can make a link to the key
KEY_ACE_SET_SECURITY Can set security
KEY_ACE_INVAL Can invalidate
KEY_ACE_REVOKE Can revoke
KEY_ACE_JOIN Can join this keyring
KEY_ACE_CLEAR Can clear this keyring
If an ACE already exists for the subject, then the permissions mask will be
overwritten; if perm is 0, it will be deleted.
Currently, the internal ACL is limited to a maximum of 16 entries.
For example:
int ret = keyctl_grant_permission(key,
KEY_ACE_SUBJ_STANDARD,
KEY_ACE_OWNER,
KEY_ACE_VIEW | KEY_ACE_READ);
Signed-off-by: David Howells <dhowells@redhat.com>
Replace the uid/gid/perm permissions checking on a key with an ACL to allow
the SETATTR and SEARCH permissions to be split. This will also allow a
greater range of subjects to represented.
============
WHY DO THIS?
============
The problem is that SETATTR and SEARCH cover a slew of actions, not all of
which should be grouped together.
For SETATTR, this includes actions that are about controlling access to a
key:
(1) Changing a key's ownership.
(2) Changing a key's security information.
(3) Setting a keyring's restriction.
And actions that are about managing a key's lifetime:
(4) Setting an expiry time.
(5) Revoking a key.
and (proposed) managing a key as part of a cache:
(6) Invalidating a key.
Managing a key's lifetime doesn't really have anything to do with
controlling access to that key.
Expiry time is awkward since it's more about the lifetime of the content
and so, in some ways goes better with WRITE permission. It can, however,
be set unconditionally by a process with an appropriate authorisation token
for instantiating a key, and can also be set by the key type driver when a
key is instantiated, so lumping it with the access-controlling actions is
probably okay.
As for SEARCH permission, that currently covers:
(1) Finding keys in a keyring tree during a search.
(2) Permitting keyrings to be joined.
(3) Invalidation.
But these don't really belong together either, since these actions really
need to be controlled separately.
Finally, there are number of special cases to do with granting the
administrator special rights to invalidate or clear keys that I would like
to handle with the ACL rather than key flags and special checks.
===============
WHAT IS CHANGED
===============
The SETATTR permission is split to create two new permissions:
(1) SET_SECURITY - which allows the key's owner, group and ACL to be
changed and a restriction to be placed on a keyring.
(2) REVOKE - which allows a key to be revoked.
The SEARCH permission is split to create:
(1) SEARCH - which allows a keyring to be search and a key to be found.
(2) JOIN - which allows a keyring to be joined as a session keyring.
(3) INVAL - which allows a key to be invalidated.
The WRITE permission is also split to create:
(1) WRITE - which allows a key's content to be altered and links to be
added, removed and replaced in a keyring.
(2) CLEAR - which allows a keyring to be cleared completely. This is
split out to make it possible to give just this to an administrator.
(3) REVOKE - see above.
Keys acquire ACLs which consist of a series of ACEs, and all that apply are
unioned together. An ACE specifies a subject, such as:
(*) Possessor - permitted to anyone who 'possesses' a key
(*) Owner - permitted to the key owner
(*) Group - permitted to the key group
(*) Everyone - permitted to everyone
Note that 'Other' has been replaced with 'Everyone' on the assumption that
you wouldn't grant a permit to 'Other' that you wouldn't also grant to
everyone else.
Further subjects may be made available by later patches.
The ACE also specifies a permissions mask. The set of permissions is now:
VIEW Can view the key metadata
READ Can read the key content
WRITE Can update/modify the key content
SEARCH Can find the key by searching/requesting
LINK Can make a link to the key
SET_SECURITY Can change owner, ACL, expiry
INVAL Can invalidate
REVOKE Can revoke
JOIN Can join this keyring
CLEAR Can clear this keyring
The KEYCTL_SETPERM function is then deprecated.
The KEYCTL_SET_TIMEOUT function then is permitted if SET_SECURITY is set,
or if the caller has a valid instantiation auth token.
The KEYCTL_INVALIDATE function then requires INVAL.
The KEYCTL_REVOKE function then requires REVOKE.
The KEYCTL_JOIN_SESSION_KEYRING function then requires JOIN to join an
existing keyring.
The JOIN permission is enabled by default for session keyrings and manually
created keyrings only.
======================
BACKWARD COMPATIBILITY
======================
To maintain backward compatibility, KEYCTL_SETPERM will translate the
permissions mask it is given into a new ACL for a key - unless
KEYCTL_SET_ACL has been called on that key, in which case an error will be
returned.
It will convert possessor, owner, group and other permissions into separate
ACEs, if each portion of the mask is non-zero.
SETATTR permission turns on all of INVAL, REVOKE and SET_SECURITY. WRITE
permission turns on WRITE, REVOKE and, if a keyring, CLEAR. JOIN is turned
on if a keyring is being altered.
The KEYCTL_DESCRIBE function translates the ACL back into a permissions
mask to return depending on possessor, owner, group and everyone ACEs.
It will make the following mappings:
(1) INVAL, JOIN -> SEARCH
(2) SET_SECURITY -> SETATTR
(3) REVOKE -> WRITE if SETATTR isn't already set
(4) CLEAR -> WRITE
Note that the value subsequently returned by KEYCTL_DESCRIBE may not match
the value set with KEYCTL_SETATTR.
=======
TESTING
=======
This passes the keyutils testsuite for all but a couple of tests:
(1) tests/keyctl/dh_compute/badargs: The first wrong-key-type test now
returns EOPNOTSUPP rather than ENOKEY as READ permission isn't removed
if the type doesn't have ->read(). You still can't actually read the
key.
(2) tests/keyctl/permitting/valid: The view-other-permissions test doesn't
work as Other has been replaced with Everyone in the ACL.
Signed-off-by: David Howells <dhowells@redhat.com>
If a key operation domain (such as a network namespace) has been removed
then attempt to garbage collect all the keys that use it.
Signed-off-by: David Howells <dhowells@redhat.com>
Move the user and user-session keyrings to the user_namespace struct rather
than pinning them from the user_struct struct. This prevents these
keyrings from propagating across user-namespaces boundaries with regard to
the KEY_SPEC_* flags, thereby making them more useful in a containerised
environment.
The issue is that a single user_struct may be represent UIDs in several
different namespaces.
The way the patch does this is by attaching a 'register keyring' in each
user_namespace and then sticking the user and user-session keyrings into
that. It can then be searched to retrieve them.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jann Horn <jannh@google.com>
Add a 'recurse' flag for keyring searches so that the flag can be omitted
and recursion disabled, thereby allowing just the nominated keyring to be
searched and none of the children.
Signed-off-by: David Howells <dhowells@redhat.com>
Cache the hash of the key's type and description in the index key so that
we're not recalculating it every time we look at a key during a search.
The hash function does a bunch of multiplications, so evading those is
probably worthwhile - especially as this is done for every key examined
during a search.
This also allows the methods used by assoc_array to get chunks of index-key
to be simplified.
Signed-off-by: David Howells <dhowells@redhat.com>
Simplify key description management by cramming the word containing the
length with the first few chars of the description also. This simplifies
the code that generates the index-key used by assoc_array. It should speed
up key searching a bit too.
Signed-off-by: David Howells <dhowells@redhat.com>
Move the RCU locks outwards from the keyring search functions so that it
will become possible to provide an RCU-capable partial request_key()
function in a later commit.
Signed-off-by: David Howells <dhowells@redhat.com>
Add a keyctl function that requests a set of capability bits to find out
what features are supported.
Signed-off-by: David Howells <dhowells@redhat.com>
Add a keyctl to atomically move a link to a key from one keyring to
another. The key must exist in "from" keyring and a flag can be given to
cause the operation to fail if there's a matching key already in the "to"
keyring.
This can be done with:
keyctl(KEYCTL_MOVE,
key_serial_t key,
key_serial_t from_keyring,
key_serial_t to_keyring,
unsigned int flags);
The key being moved must grant Link permission and both keyrings must grant
Write permission.
flags should be 0 or KEYCTL_MOVE_EXCL, with the latter preventing
displacement of a matching key from the "to" keyring.
Signed-off-by: David Howells <dhowells@redhat.com>
Hoist the locking of out of __key_link_begin() and into its callers. This
is necessary to allow the upcoming key_move() operation to correctly order
taking of the source keyring semaphore, the destination keyring semaphore
and the keyring serialisation lock.
Signed-off-by: David Howells <dhowells@redhat.com>
Based on 1 normalized pattern(s):
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
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the request_key() upcall mechanism there's a dependency loop by which if
a key type driver overrides the ->request_key hook and the userspace side
manages to lose the authorisation key, the auth key and the internal
construction record (struct key_construction) can keep each other pinned.
Fix this by the following changes:
(1) Killing off the construction record and using the auth key instead.
(2) Including the operation name in the auth key payload and making the
payload available outside of security/keys/.
(3) The ->request_key hook is given the authkey instead of the cons
record and operation name.
Changes (2) and (3) allow the auth key to naturally be cleaned up if the
keyring it is in is destroyed or cleared or the auth key is unlinked.
Fixes: 7ee02a316600 ("keys: Fix dependency loop between construction record and auth key")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
Export lookup_user_key() symbol in order to allow nvdimm passphrase
update to retrieve user injected keys.
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Provide five keyctl functions that permit userspace to make use of the new
key type ops for accessing and driving asymmetric keys.
(*) Query an asymmetric key.
long keyctl(KEYCTL_PKEY_QUERY,
key_serial_t key, unsigned long reserved,
struct keyctl_pkey_query *info);
Get information about an asymmetric key. The information is returned
in the keyctl_pkey_query struct:
__u32 supported_ops;
A bit mask of flags indicating which ops are supported. This is
constructed from a bitwise-OR of:
KEYCTL_SUPPORTS_{ENCRYPT,DECRYPT,SIGN,VERIFY}
__u32 key_size;
The size in bits of the key.
__u16 max_data_size;
__u16 max_sig_size;
__u16 max_enc_size;
__u16 max_dec_size;
The maximum sizes in bytes of a blob of data to be signed, a signature
blob, a blob to be encrypted and a blob to be decrypted.
reserved must be set to 0. This is intended for future use to hand
over one or more passphrases needed unlock a key.
If successful, 0 is returned. If the key is not an asymmetric key,
EOPNOTSUPP is returned.
(*) Encrypt, decrypt, sign or verify a blob using an asymmetric key.
long keyctl(KEYCTL_PKEY_ENCRYPT,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);
long keyctl(KEYCTL_PKEY_DECRYPT,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);
long keyctl(KEYCTL_PKEY_SIGN,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);
long keyctl(KEYCTL_PKEY_VERIFY,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
const void *in2);
Use an asymmetric key to perform a public-key cryptographic operation
a blob of data.
The parameter block pointed to by params contains a number of integer
values:
__s32 key_id;
__u32 in_len;
__u32 out_len;
__u32 in2_len;
For a given operation, the in and out buffers are used as follows:
Operation ID in,in_len out,out_len in2,in2_len
======================= =============== =============== ===========
KEYCTL_PKEY_ENCRYPT Raw data Encrypted data -
KEYCTL_PKEY_DECRYPT Encrypted data Raw data -
KEYCTL_PKEY_SIGN Raw data Signature -
KEYCTL_PKEY_VERIFY Raw data - Signature
info is a string of key=value pairs that supply supplementary
information.
The __spare space in the parameter block must be set to 0. This is
intended, amongst other things, to allow the passing of passphrases
required to unlock a key.
If successful, encrypt, decrypt and sign all return the amount of data
written into the output buffer. Verification returns 0 on success.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Denis Kenzior <denkenz@gmail.com>
Tested-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
The 'struct key' will use 'time_t' which we try to remove in the
kernel, since 'time_t' is not year 2038 safe on 32bit systems.
Also the 'struct keyring_search_context' will use 'timespec' type
to record current time, which is also not year 2038 safe on 32bit
systems.
Thus this patch replaces 'time_t' with 'time64_t' which is year 2038
safe for 'struct key', and replace 'timespec' with 'time64_t' for the
'struct keyring_search_context', since we only look at the the seconds
part of 'timespec' variable. Moreover we also change the codes where
using the 'time_t' and 'timespec', and we can get current time by
ktime_get_real_seconds() instead of current_kernel_time(), and use
'TIME64_MAX' macro to initialize the 'time64_t' type variable.
Especially in proc.c file, we have replaced 'unsigned long' and 'timespec'
type with 'u64' and 'time64_t' type to save the timeout value, which means
user will get one 'u64' type timeout value by issuing proc_keys_show()
function.
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
It was possible for an unprivileged user to create the user and user
session keyrings for another user. For example:
sudo -u '#3000' sh -c 'keyctl add keyring _uid.4000 "" @u
keyctl add keyring _uid_ses.4000 "" @u
sleep 15' &
sleep 1
sudo -u '#4000' keyctl describe @u
sudo -u '#4000' keyctl describe @us
This is problematic because these "fake" keyrings won't have the right
permissions. In particular, the user who created them first will own
them and will have full access to them via the possessor permissions,
which can be used to compromise the security of a user's keys:
-4: alswrv-----v------------ 3000 0 keyring: _uid.4000
-5: alswrv-----v------------ 3000 0 keyring: _uid_ses.4000
Fix it by marking user and user session keyrings with a flag
KEY_FLAG_UID_KEYRING. Then, when searching for a user or user session
keyring by name, skip all keyrings that don't have the flag set.
Fixes: 69664cf16a ("keys: don't generate user and user session keyrings unless they're accessed")
Cc: <stable@vger.kernel.org> [v2.6.26+]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
randstruct plugin, including the task_struct.
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Merge tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull structure randomization updates from Kees Cook:
"Now that IPC and other changes have landed, enable manual markings for
randstruct plugin, including the task_struct.
This is the rest of what was staged in -next for the gcc-plugins, and
comes in three patches, largest first:
- mark "easy" structs with __randomize_layout
- mark task_struct with an optional anonymous struct to isolate the
__randomize_layout section
- mark structs to opt _out_ of automated marking (which will come
later)
And, FWIW, this continues to pass allmodconfig (normal and patched to
enable gcc-plugins) builds of x86_64, i386, arm64, arm, powerpc, and
s390 for me"
* tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
randstruct: opt-out externally exposed function pointer structs
task_struct: Allow randomized layout
randstruct: Mark various structs for randomization
This marks many critical kernel structures for randomization. These are
structures that have been targeted in the past in security exploits, or
contain functions pointers, pointers to function pointer tables, lists,
workqueues, ref-counters, credentials, permissions, or are otherwise
sensitive. This initial list was extracted from Brad Spengler/PaX Team's
code in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.
Left out of this list is task_struct, which requires special handling
and will be covered in a subsequent patch.
Signed-off-by: Kees Cook <keescook@chromium.org>
The wait_bit*() types and APIs are mixed into wait.h, but they
are a pretty orthogonal extension of wait-queues.
Furthermore, only about 50 kernel files use these APIs, while
over 1000 use the regular wait-queue functionality.
So clean up the main wait.h by moving the wait-bit functionality
out of it, into a separate .h and .c file:
include/linux/wait_bit.h for types and APIs
kernel/sched/wait_bit.c for the implementation
Update all header dependencies.
This reduces the size of wait.h rather significantly, by about 30%.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
SP800-56A defines the use of DH with key derivation function based on a
counter. The input to the KDF is defined as (DH shared secret || other
information). The value for the "other information" is to be provided by
the caller.
The KDF is implemented using the hash support from the kernel crypto API.
The implementation uses the symmetric hash support as the input to the
hash operation is usually very small. The caller is allowed to specify
the hash name that he wants to use to derive the key material allowing
the use of all supported hashes provided with the kernel crypto API.
As the KDF implements the proper truncation of the DH shared secret to
the requested size, this patch fills the caller buffer up to its size.
The patch is tested with a new test added to the keyutils user space
code which uses a CAVS test vector testing the compliance with
SP800-56A.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Keyrings recently gained restrict_link capabilities that allow
individual keys to be validated prior to linking. This functionality
was only available using internal kernel APIs.
With the KEYCTL_RESTRICT_KEYRING command existing keyrings can be
configured to check the content of keys before they are linked, and
then allow or disallow linkage of that key to the keyring.
To restrict a keyring, call:
keyctl(KEYCTL_RESTRICT_KEYRING, key_serial_t keyring, const char *type,
const char *restriction)
where 'type' is the name of a registered key type and 'restriction' is a
string describing how key linkage is to be restricted. The restriction
option syntax is specific to each key type.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Replace struct key's restrict_link function pointer with a pointer to
the new struct key_restriction. The structure contains pointers to the
restriction function as well as relevant data for evaluating the
restriction.
The garbage collector checks restrict_link->keytype when key types are
unregistered. Restrictions involving a removed key type are converted
to use restrict_link_reject so that restrictions cannot be removed by
unregistering key types.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The values computed during Diffie-Hellman key exchange are often used
in combination with key derivation functions to create cryptographic
keys. Add a placeholder for a later implementation to configure a
key derivation function that will transform the Diffie-Hellman
result returned by the KEYCTL_DH_COMPUTE command.
[This patch was stripped down from a patch produced by Mat Martineau that
had a bug in the compat code - so for the moment Stephan's patch simply
requires that the placeholder argument must be NULL]
Original-signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
This adds userspace access to Diffie-Hellman computations through a
new keyctl() syscall command to calculate shared secrets or public
keys using input parameters stored in the keyring.
Input key ids are provided in a struct due to the current 5-arg limit
for the keyctl syscall. Only user keys are supported in order to avoid
exposing the content of logon or encrypted keys.
The output is written to the provided buffer, based on the assumption
that the values are only needed in userspace.
Future support for other types of key derivation would involve a new
command, like KEYCTL_ECDH_COMPUTE.
Once Diffie-Hellman support is included in the crypto API, this code
can be converted to use the crypto API to take advantage of possible
hardware acceleration and reduce redundant code.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Since the keyring facility can be viewed as a cache (at least in some
applications), the local expiration time on the key should probably be viewed
as a 'needs updating after this time' property rather than an absolute 'anyone
now wanting to use this object is out of luck' property.
Since request_key() is the main interface for the usage of keys, this should
update or replace an expired key rather than issuing EKEYEXPIRED if the local
expiration has been reached (ie. it should refresh the cache).
For absolute conditions where refreshing the cache probably doesn't help, the
key can be negatively instantiated using KEYCTL_REJECT_KEY with EKEYEXPIRED
given as the error to issue. This will still cause request_key() to return
EKEYEXPIRED as that was explicitly set.
In the future, if the key type has an update op available, we might want to
upcall with the expired key and allow the upcall to update it. We would pass
a different operation name (the first column in /etc/request-key.conf) to the
request-key program.
request_key() returning EKEYEXPIRED is causing an NFS problem which Chuck
Lever describes thusly:
After about 10 minutes, my NFSv4 functional tests fail because the
ownership of the test files goes to "-2". Looking at /proc/keys
shows that the id_resolv keys that map to my test user ID have
expired. The ownership problem persists until the expired keys are
purged from the keyring, and fresh keys are obtained.
I bisected the problem to 3.13 commit b2a4df200d ("KEYS: Expand
the capacity of a keyring"). This commit inadvertantly changes the
API contract of the internal function keyring_search_aux().
The root cause appears to be that b2a4df200d made "no state check"
the default behavior. "No state check" means the keyring search
iterator function skips checking the key's expiry timeout, and
returns expired keys. request_key_and_link() depends on getting
an -EAGAIN result code to know when to perform an upcall to refresh
an expired key.
This patch can be tested directly by:
keyctl request2 user debug:fred a @s
keyctl timeout %user:debug:fred 3
sleep 4
keyctl request2 user debug:fred a @s
Without the patch, the last command gives error EKEYEXPIRED, but with the
command it gives a new key.
Reported-by: Carl Hetherington <cth@carlh.net>
Reported-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Chuck Lever <chuck.lever@oracle.com>
Make the key matching functions pointed to by key_match_data::cmp return bool
rather than int.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
A previous patch added a ->match_preparse() method to the key type. This is
allowed to override the function called by the iteration algorithm.
Therefore, we can just set a default that simply checks for an exact match of
the key description with the original criterion data and allow match_preparse
to override it as needed.
The key_type::match op is then redundant and can be removed, as can the
user_match() function.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Remove key_type::def_lookup_type as it's no longer used. The information now
defaults to KEYRING_SEARCH_LOOKUP_DIRECT but may be overridden by
type->match_preparse().
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Preparse the match data. This provides several advantages:
(1) The preparser can reject invalid criteria up front.
(2) The preparser can convert the criteria to binary data if necessary (the
asymmetric key type really wants to do binary comparison of the key IDs).
(3) The preparser can set the type of search to be performed. This means
that it's not then a one-off setting in the key type.
(4) The preparser can set an appropriate comparator function.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Move the flags representing required permission to linux/key.h as the perm
parameter of security_key_permission() is in terms of them - and not the
permissions mask flags used in key->perm.
Whilst we're at it:
(1) Rename them to be KEY_NEED_xxx rather than KEY_xxx to avoid collisions
with symbols in uapi/linux/input.h.
(2) Don't use key_perm_t for a mask of required permissions, but rather limit
it to the permissions mask attached to the key and arguments related
directly to that.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Add support for per-user_namespace registers of persistent per-UID kerberos
caches held within the kernel.
This allows the kerberos cache to be retained beyond the life of all a user's
processes so that the user's cron jobs can work.
The kerberos cache is envisioned as a keyring/key tree looking something like:
struct user_namespace
\___ .krb_cache keyring - The register
\___ _krb.0 keyring - Root's Kerberos cache
\___ _krb.5000 keyring - User 5000's Kerberos cache
\___ _krb.5001 keyring - User 5001's Kerberos cache
\___ tkt785 big_key - A ccache blob
\___ tkt12345 big_key - Another ccache blob
Or possibly:
struct user_namespace
\___ .krb_cache keyring - The register
\___ _krb.0 keyring - Root's Kerberos cache
\___ _krb.5000 keyring - User 5000's Kerberos cache
\___ _krb.5001 keyring - User 5001's Kerberos cache
\___ tkt785 keyring - A ccache
\___ krbtgt/REDHAT.COM@REDHAT.COM big_key
\___ http/REDHAT.COM@REDHAT.COM user
\___ afs/REDHAT.COM@REDHAT.COM user
\___ nfs/REDHAT.COM@REDHAT.COM user
\___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key
\___ http/KERNEL.ORG@KERNEL.ORG big_key
What goes into a particular Kerberos cache is entirely up to userspace. Kernel
support is limited to giving you the Kerberos cache keyring that you want.
The user asks for their Kerberos cache by:
krb_cache = keyctl_get_krbcache(uid, dest_keyring);
The uid is -1 or the user's own UID for the user's own cache or the uid of some
other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to
mess with the cache.
The cache returned is a keyring named "_krb.<uid>" that the possessor can read,
search, clear, invalidate, unlink from and add links to. Active LSMs get a
chance to rule on whether the caller is permitted to make a link.
Each uid's cache keyring is created when it first accessed and is given a
timeout that is extended each time this function is called so that the keyring
goes away after a while. The timeout is configurable by sysctl but defaults to
three days.
Each user_namespace struct gets a lazily-created keyring that serves as the
register. The cache keyrings are added to it. This means that standard key
search and garbage collection facilities are available.
The user_namespace struct's register goes away when it does and anything left
in it is then automatically gc'd.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>
cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
