This is effectively a revert of 7b9a7ec5
plus fixing it a different way...

We found, when trying to run an application from an application which
had dropped privs that the kernel does security checks on undefined
capability bits.  This was ESPECIALLY difficult to debug as those
undefined bits are hidden from /proc/$PID/status.

Consider a root application which drops all capabilities from ALL 4
capability sets.  We assume, since the application is going to set
eff/perm/inh from an array that it will clear not only the defined caps
less than CAP_LAST_CAP, but also the higher 28ish bits which are
undefined future capabilities.

The BSET gets cleared differently.  Instead it is cleared one bit at a
time.  The problem here is that in security/commoncap.c::cap_task_prctl()
we actually check the validity of a capability being read.  So any task
which attempts to 'read all things set in bset' followed by 'unset all
things set in bset' will not even attempt to unset the undefined bits
higher than CAP_LAST_CAP.

So the 'parent' will look something like:
CapInh:	0000000000000000
CapPrm:	0000000000000000
CapEff:	0000000000000000
CapBnd:	ffffffc000000000

All of this 'should' be fine.  Given that these are undefined bits that
aren't supposed to have anything to do with permissions.  But they do...

So lets now consider a task which cleared the eff/perm/inh completely
and cleared all of the valid caps in the bset (but not the invalid caps
it couldn't read out of the kernel).  We know that this is exactly what
the libcap-ng library does and what the go capabilities library does.
They both leave you in that above situation if you try to clear all of
you capapabilities from all 4 sets.  If that root task calls execve()
the child task will pick up all caps not blocked by the bset.  The bset
however does not block bits higher than CAP_LAST_CAP.  So now the child
task has bits in eff which are not in the parent.  These are
'meaningless' undefined bits, but still bits which the parent doesn't
have.

The problem is now in cred_cap_issubset() (or any operation which does a
subset test) as the child, while a subset for valid cap bits, is not a
subset for invalid cap bits!  So now we set durring commit creds that
the child is not dumpable.  Given it is 'more priv' than its parent.  It
also means the parent cannot ptrace the child and other stupidity.

The solution here:
1) stop hiding capability bits in status
	This makes debugging easier!

2) stop giving any task undefined capability bits.  it's simple, it you
don't put those invalid bits in CAP_FULL_SET you won't get them in init
and you won't get them in any other task either.
	This fixes the cap_issubset() tests and resulting fallout (which
	made the init task in a docker container untraceable among other
	things)

3) mask out undefined bits when sys_capset() is called as it might use
~0, ~0 to denote 'all capabilities' for backward/forward compatibility.
	This lets 'capsh --caps="all=eip" -- -c /bin/bash' run.

4) mask out undefined bit when we read a file capability off of disk as
again likely all bits are set in the xattr for forward/backward
compatibility.
	This lets 'setcap all+pe /bin/bash; /bin/bash' run
Signed-off-by: Eric Paris <eparis@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Andrew G. Morgan <morgan@kernel.org>
Cc: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Steve Grubb <sgrubb@redhat.com>
Cc: Dan Walsh <dwalsh@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>

Merge tag 'keys-next-20140722' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into next

In function cap_task_prctl(), we would allocate a credential
unconditionally and then check if we support the requested function.
If not we would release this credential with abort_creds() by using
RCU method. But on some archs such as powerpc, the sys_prctl is heavily
used to get/set the floating point exception mode. So the unnecessary
allocating/releasing of credential not only introduce runtime overhead
but also do cause OOM due to the RCU implementation.

This patch removes abort_creds() from cap_task_prctl() by calling
prepare_creds() only when we need to modify it.
Reported-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>

Signed-off-by: David Howells <dhowells@redhat.com>

Signed-off-by: David Howells <dhowells@redhat.com>

Here's a set of changes that implement a PE file signature checker.

This provides the following facility:

 (1) Extract the signature from the PE file.  This is a PKCS#7 message
     containing, as its data, a hash of the signed parts of the file.

 (2) Digest the signed parts of the file.

 (3) Compare the digest with the one from the PKCS#7 message.

 (4) Validate the signatures on the PKCS#7 message and indicate
     whether it was matched by a trusted key.
Signed-off-by: David Howells <dhowells@redhat.com>

Here's a set of changes that implement a PKCS#7 message parser in the kernel.

The PKCS#7 message parsing will then be used to limit kexec to authenticated
kernels only if so configured.

The changes provide the following facilities:

 (1) Parse an ASN.1 PKCS#7 message and pick out useful bits such as the data
     content and the X.509 certificates used to sign it and all the data
     signatures.

 (2) Verify all the data signatures against the set of X.509 certificates
     available in the message.

 (3) Follow the certificate chains and verify that:

     (a) for every self-signed X.509 certificate, check that it validly signed
     	 itself, and:

     (b) for every non-self-signed certificate, if we have a 'parent'
     	 certificate, the former is validly signed by the latter.

 (4) Look for intersections between the certificate chains and the trusted
     keyring, if any intersections are found, verify that the trusted
     certificates signed the intersection point in the chain.

 (5) For testing purposes, a key type can be made available that will take a
     PKCS#7 message, check that the message is trustworthy, and if so, add its
     data content into the key.

Note that (5) has to be altered to take account of the preparsing patches
already committed to this branch.
Signed-off-by: David Howells <dhowells@redhat.com>

Here are a set of changes that make all but encrypted and trusted keys use
preparsing.  Unfortunately, encrypted and trusted keys incorrectly use the
update op to alter a key, so other changes will need to be made for them.

These changes permit payload parsing when instantiating or updating a key to be
done before locks are taken and to determine the amount of quota that will be
required in advance.  The latter will make it possible to do LRU discard before
any locks are taken.
Signed-off-by: David Howells <dhowells@redhat.com>

Provide key preparsing for the request_key_auth key type so that we can make
preparsing mandatory.  This does nothing as this type can only be set up
internally to the kernel.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>

Provide key preparsing in the keyring so that we can make preparsing
mandatory.  For keyrings, however, only an empty payload is permitted.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>

Make use of key preparsing in the big key type so that quota size determination
can take place prior to keyring locking when a key is being added.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>

Make use of key preparsing in the RxRPC protocol so that quota size
determination can take place prior to keyring locking when a key is being
added.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>

Make use of key preparsing in the DNS resolver so that quota size determination
can take place prior to keyring locking when a key is being added.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>

Ceph can use user_match() instead of defining its own identical function.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>
cc: Tommi Virtanen <tommi.virtanen@dreamhost.com>

Make use of key preparsing in Ceph so that quota size determination can take
place prior to keyring locking when a key is being added.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>
cc: Tommi Virtanen <tommi.virtanen@dreamhost.com>

Make use of key preparsing in user-defined and logon keys so that quota size
determination can take place prior to keyring locking when a key is being
added.

Also the idmapper key types need to change to match as they use the
user-defined key type routines.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>

Call the ->free_preparse() key type op even after ->preparse() returns an
error as it does cleaning up type stuff.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>

Allow a key type's preparsing routine to set the expiry time for a key.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>

struct key_preparsed_payload should have two payload pointers to correspond
with those in struct key.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>

Applying restrictive seccomp filter programs to large or diverse
codebases often requires handling threads which may be started early in
the process lifetime (e.g., by code that is linked in). While it is
possible to apply permissive programs prior to process start up, it is
difficult to further restrict the kernel ABI to those threads after that
point.

This change adds a new seccomp syscall flag to SECCOMP_SET_MODE_FILTER for
synchronizing thread group seccomp filters at filter installation time.

When calling seccomp(SECCOMP_SET_MODE_FILTER, SECCOMP_FILTER_FLAG_TSYNC,
filter) an attempt will be made to synchronize all threads in current's
threadgroup to its new seccomp filter program. This is possible iff all
threads are using a filter that is an ancestor to the filter current is
attempting to synchronize to. NULL filters (where the task is running as
SECCOMP_MODE_NONE) are also treated as ancestors allowing threads to be
transitioned into SECCOMP_MODE_FILTER. If prctrl(PR_SET_NO_NEW_PRIVS,
...) has been set on the calling thread, no_new_privs will be set for
all synchronized threads too. On success, 0 is returned. On failure,
the pid of one of the failing threads will be returned and no filters
will have been applied.

The race conditions against another thread are:
- requesting TSYNC (already handled by sighand lock)
- performing a clone (already handled by sighand lock)
- changing its filter (already handled by sighand lock)
- calling exec (handled by cred_guard_mutex)
The clone case is assisted by the fact that new threads will have their
seccomp state duplicated from their parent before appearing on the tasklist.

Holding cred_guard_mutex means that seccomp filters cannot be assigned
while in the middle of another thread's exec (potentially bypassing
no_new_privs or similar). The call to de_thread() may kill threads waiting
for the mutex.

Changes across threads to the filter pointer includes a barrier.

Based on patches by Will Drewry.
Suggested-by: Julien Tinnes <jln@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

This changes the mode setting helper to allow threads to change the
seccomp mode from another thread. We must maintain barriers to keep
TIF_SECCOMP synchronized with the rest of the seccomp state.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

Normally, task_struct.seccomp.filter is only ever read or modified by
the task that owns it (current). This property aids in fast access
during system call filtering as read access is lockless.

Updating the pointer from another task, however, opens up race
conditions. To allow cross-thread filter pointer updates, writes to the
seccomp fields are now protected by the sighand spinlock (which is shared
by all threads in the thread group). Read access remains lockless because
pointer updates themselves are atomic.  However, writes (or cloning)
often entail additional checking (like maximum instruction counts)
which require locking to perform safely.

In the case of cloning threads, the child is invisible to the system
until it enters the task list. To make sure a child can't be cloned from
a thread and left in a prior state, seccomp duplication is additionally
moved under the sighand lock. Then parent and child are certain have
the same seccomp state when they exit the lock.

Based on patches by Will Drewry and David Drysdale.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

In preparation for adding seccomp locking, move filter creation away
from where it is checked and applied. This will allow for locking where
no memory allocation is happening. The validation, filter attachment,
and seccomp mode setting can all happen under the future locks.

For extreme defensiveness, I've added a BUG_ON check for the calculated
size of the buffer allocation in case BPF_MAXINSN ever changes, which
shouldn't ever happen. The compiler should actually optimize out this
check since the test above it makes it impossible.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

Since seccomp transitions between threads requires updates to the
no_new_privs flag to be atomic, the flag must be part of an atomic flag
set. This moves the nnp flag into a separate task field, and introduces
accessors.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

Wires up the new seccomp syscall.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>

Wires up the new seccomp syscall.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>

This adds the new "seccomp" syscall with both an "operation" and "flags"
parameter for future expansion. The third argument is a pointer value,
used with the SECCOMP_SET_MODE_FILTER operation. Currently, flags must
be 0. This is functionally equivalent to prctl(PR_SET_SECCOMP, ...).

In addition to the TSYNC flag later in this patch series, there is a
non-zero chance that this syscall could be used for configuring a fixed
argument area for seccomp-tracer-aware processes to pass syscall arguments
in the future. Hence, the use of "seccomp" not simply "seccomp_add_filter"
for this syscall. Additionally, this syscall uses operation, flags,
and user pointer for arguments because strictly passing arguments via
a user pointer would mean seccomp itself would be unable to trivially
filter the seccomp syscall itself.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

Separates the two mode setting paths to make things more readable with
fewer #ifdefs within function bodies.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

To support splitting mode 1 from mode 2, extract the mode checking and
assignment logic into common functions.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

In preparation for having other callers of the seccomp mode setting
logic, split the prctl entry point away from the core logic that performs
seccomp mode setting.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>

Add myself as seccomp maintainer.
Suggested-by: James Morris <jmorris@namei.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

Provide a generic instantiation function for key types that use the preparse
hook.  This makes it easier to prereserve key quota before keyrings get locked
to retain the new key.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Sage Weil <sage@redhat.com>

When SIGNATURE=y but depends on CRYPTO=m, it selects MPILIB as module
producing build break. This patch makes digsig to select crypto for
correcting dependency.
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>

You can select MPILIB_EXTRA all you want, it doesn't exist ;-)

Surprised kconfig doesn't complain about that...
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>

Special kernel keys, such as those used to hold DNS results for AFS, CIFS and
NFS and those used to hold idmapper results for NFS, used to be
'invalidateable' with key_revoke().  However, since the default permissions for
keys were reduced:

	Commit: 96b5c8fe
	KEYS: Reduce initial permissions on keys

it has become impossible to do this.

Add a key flag (KEY_FLAG_ROOT_CAN_INVAL) that will permit a key to be
invalidated by root.  This should not be used for system keyrings as the
garbage collector will try and remove any invalidate key.  For system keyrings,
KEY_FLAG_ROOT_CAN_CLEAR can be used instead.

After this, from userspace, keyctl_invalidate() and "keyctl invalidate" can be
used by any possessor of CAP_SYS_ADMIN (typically root) to invalidate DNS and
idmapper keys.  Invalidated keys are immediately garbage collected and will be
immediately rerequested if needed again.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Steve Dickson <steved@redhat.com>

Require all keys added to the IMA keyring be signed by an
existing trusted key on the system trusted keyring.

Changelog v6:
- remove ifdef CONFIG_IMA_TRUSTED_KEYRING in C code - Dmitry
- update Kconfig dependency and help
- select KEYS_DEBUG_PROC_KEYS - Dmitry

Changelog v5:
- Move integrity_init_keyring() to init_ima() - Dmitry
- reset keyring[id] on failure - Dmitry

Changelog v1:
- don't link IMA trusted keyring to user keyring

Changelog:
- define stub integrity_init_keyring() function (reported-by Fengguang Wu)
- differentiate between regular and trusted keyring names.
- replace printk with pr_info (D. Kasatkin)
- only make the IMA keyring a trusted keyring (reported-by D. Kastatkin)
- define stub integrity_init_keyring() definition based on
  CONFIG_INTEGRITY_SIGNATURE, not CONFIG_INTEGRITY_ASYMMETRIC_KEYS.
  (reported-by Jim Davis)
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Acked-by: David Howells <dhowells@redhat.com>

Instead of allowing public keys, with certificates signed by any
key on the system trusted keyring, to be added to a trusted keyring,
this patch further restricts the certificates to those signed only by
builtin keys on the system keyring.

This patch defines a new option 'builtin' for the kernel parameter
'keys_ownerid' to allow trust validation using builtin keys.

Simplified Mimi's "KEYS: define an owner trusted keyring" patch

Changelog v7:
- rename builtin_keys to use_builtin_keys
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

Instead of allowing public keys, with certificates signed by any
key on the system trusted keyring, to be added to a trusted keyring,
this patch further restricts the certificates to those signed by a
particular key on the system keyring.

This patch defines a new kernel parameter 'ca_keys' to identify the
specific key which must be used for trust validation of certificates.

Simplified Mimi's "KEYS: define an owner trusted keyring" patch.

Changelog:
- support for builtin x509 public keys only
- export "asymmetric_keyid_match"
- remove ifndefs MODULE
- rename kernel boot parameter from keys_ownerid to ca_keys
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>