security_inode_getsecurity() provides the text string value
of a security attribute. It does not provide a "secctx".
The code in xattr_getsecurity() that calls security_inode_getsecurity()
and then calls security_release_secctx() happened to work because
SElinux and Smack treat the attribute and the secctx the same way.
It fails for cap_inode_getsecurity(), because that module has no
secctx that ever needs releasing. It turns out that Smack is the
one that's doing things wrong by not allocating memory when instructed
to do so by the "alloc" parameter.
The fix is simple enough. Change the security_release_secctx() to
kfree() because it isn't a secctx being returned by
security_inode_getsecurity(). Change Smack to allocate the string when
told to do so.
Note: this also fixes memory leaks for LSMs which implement
inode_getsecurity but not release_secctx, such as capabilities.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reported-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>
From David Howells:
"There are two sets of patches here:
(1) A bunch of core keyrings bug fixes from Eric Biggers.
(2) Fixing big_key to use safe crypto from Jason A. Donenfeld."
This started out as just replacing the use of crypto/rng with
get_random_bytes_wait, so that we wouldn't use bad randomness at boot
time. But, upon looking further, it appears that there were even deeper
underlying cryptographic problems, and that this seems to have been
committed with very little crypto review. So, I rewrote the whole thing,
trying to keep to the conventions introduced by the previous author, to
fix these cryptographic flaws.
It makes no sense to seed crypto/rng at boot time and then keep
using it like this, when in fact there's already get_random_bytes_wait,
which can ensure there's enough entropy and be a much more standard way
of generating keys. Since this sensitive material is being stored
untrusted, using ECB and no authentication is simply not okay at all. I
find it surprising and a bit horrifying that this code even made it past
basic crypto review, which perhaps points to some larger issues. This
patch moves from using AES-ECB to using AES-GCM. Since keys are uniquely
generated each time, we can set the nonce to zero. There was also a race
condition in which the same key would be reused at the same time in
different threads. A mutex fixes this issue now.
So, to summarize, this commit fixes the following vulnerabilities:
* Low entropy key generation, allowing an attacker to potentially
guess or predict keys.
* Unauthenticated encryption, allowing an attacker to modify the
cipher text in particular ways in order to manipulate the plaintext,
which is is even more frightening considering the next point.
* Use of ECB mode, allowing an attacker to trivially swap blocks or
compare identical plaintext blocks.
* Key re-use.
* Faulty memory zeroing.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kirill Marinushkin <k.marinushkin@gmail.com>
Cc: security@kernel.org
Cc: stable@vger.kernel.org
kmemdup() is preferred to kmalloc() followed by memcpy().
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
When checking for permission to view keys whilst reading from
/proc/keys, we should use the credentials with which the /proc/keys file
was opened. This is because, in a classic type of exploit, it can be
possible to bypass checks for the *current* credentials by passing the
file descriptor to a suid program.
Following commit 34dbbcdbf6 ("Make file credentials available to the
seqfile interfaces") we can finally fix it. So let's do it.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
In key_user_lookup(), if there is no key_user for the given uid, we drop
key_user_lock, allocate a new key_user, and search the tree again. But
we failed to set 'parent' to NULL at the beginning of the second search.
If the tree were to be empty for the second search, the insertion would
be done with an invalid 'parent', scribbling over freed memory.
Fortunately this can't actually happen currently because the tree always
contains at least the root_key_user. But it still should be fixed to
make the code more robust.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.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>
Userspace can call keyctl_read() on a keyring to get the list of IDs of
keys in the keyring. But if the user-supplied buffer is too small, the
kernel would write the full list anyway --- which will corrupt whatever
userspace memory happened to be past the end of the buffer. Fix it by
only filling the space that is available.
Fixes: b2a4df200d ("KEYS: Expand the capacity of a keyring")
Cc: <stable@vger.kernel.org> [v3.13+]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
In keyctl_read_key(), if key_permission() were to return an error code
other than EACCES, we would leak a the reference to the key. This can't
actually happen currently because key_permission() can only return an
error code other than EACCES if security_key_permission() does, only
SELinux and Smack implement that hook, and neither can return an error
code other than EACCES. But it should still be fixed, as it is a bug
waiting to happen.
Fixes: 29db919063 ("[PATCH] Keys: Add LSM hooks for key management [try #3]")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
In keyctl_assume_authority(), if keyctl_change_reqkey_auth() were to
fail, we would leak the reference to the 'authkey'. Currently this can
only happen if prepare_creds() fails to allocate memory. But it still
should be fixed, as it is a more severe bug waiting to happen.
This patch also moves the read of 'authkey->serial' to before the
reference to the authkey is dropped. Doing the read after dropping the
reference is very fragile because it assumes we still hold another
reference to the key. (Which we do, in current->cred->request_key_auth,
but there's no reason not to write it in the "obviously correct" way.)
Fixes: d84f4f992c ("CRED: Inaugurate COW credentials")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
If key_instantiate_and_link() were to fail (which fortunately isn't
possible currently), the call to key_revoke(authkey) would crash with a
NULL pointer dereference in request_key_auth_revoke() because the key
has not yet been instantiated.
Fix this by removing the call to key_revoke(). key_put() is sufficient,
as it's not possible for an uninstantiated authkey to have been used for
anything yet.
Fixes: b5f545c880 ("[PATCH] keys: Permit running process to instantiate keys")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
In request_key_auth_new(), if key_alloc() or key_instantiate_and_link()
were to fail, we would leak a reference to the 'struct cred'. Currently
this can only happen if key_alloc() fails to allocate memory. But it
still should be fixed, as it is a more severe bug waiting to happen.
Fix it by cleaning things up to use a helper function which frees a
'struct request_key_auth' correctly.
Fixes: d84f4f992c ("CRED: Inaugurate COW credentials")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Pull misc security layer update from James Morris:
"This is the remaining 'general' change in the security tree for v4.14,
following the direct merging of SELinux (+ TOMOYO), AppArmor, and
seccomp.
That's everything now for the security tree except IMA, which will
follow shortly (I've been traveling for the past week with patchy
internet)"
* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
security: fix description of values returned by cap_inode_need_killpriv
cap_inode_need_killpriv returns 1 if security.capability exists and
has a value and inode_killpriv() is required, 0 otherwise. Fix the
description of the return value to reflect this.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Pull apparmor updates from John Johansen:
"This is the apparmor pull request, similar to SELinux and seccomp.
It's the same series that I was sent to James' security tree + one
regression fix that was found after the series was sent to James and
would have been sent for v4.14-rc2.
Features:
- in preparation for secid mapping add support for absolute root view
based labels
- add base infastructure for socket mediation
- add mount mediation
- add signal mediation
minor cleanups and changes:
- be defensive, ensure unconfined profiles have dfas initialized
- add more debug asserts to apparmorfs
- enable policy unpacking to audit different reasons for failure
- cleanup conditional check for label in label_print
- Redundant condition: prev_ns. in [label.c:1498]
Bug Fixes:
- fix regression in apparmorfs DAC access permissions
- fix build failure on sparc caused by undeclared signals
- fix sparse report of incorrect type assignment when freeing label proxies
- fix race condition in null profile creation
- Fix an error code in aafs_create()
- Fix logical error in verify_header()
- Fix shadowed local variable in unpack_trans_table()"
* tag 'apparmor-pr-2017-09-22' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
apparmor: fix apparmorfs DAC access permissions
apparmor: fix build failure on sparc caused by undeclared signals
apparmor: fix incorrect type assignment when freeing proxies
apparmor: ensure unconfined profiles have dfas initialized
apparmor: fix race condition in null profile creation
apparmor: move new_null_profile to after profile lookup fns()
apparmor: add base infastructure for socket mediation
apparmor: add more debug asserts to apparmorfs
apparmor: make policy_unpack able to audit different info messages
apparmor: add support for absolute root view based labels
apparmor: cleanup conditional check for label in label_print
apparmor: add mount mediation
apparmor: add the ability to mediate signals
apparmor: Redundant condition: prev_ns. in [label.c:1498]
apparmor: Fix an error code in aafs_create()
apparmor: Fix logical error in verify_header()
apparmor: Fix shadowed local variable in unpack_trans_table()
The DAC access permissions for several apparmorfs files are wrong.
.access - needs to be writable by all tasks to perform queries
the others in the set only provide a read fn so should be read only.
With policy namespace virtualization all apparmor needs to control
the permission and visibility checks directly which means DAC
access has to be allowed for all user, group, and other.
BugLink: http://bugs.launchpad.net/bugs/1713103
Fixes: c97204baf8 ("apparmor: rename apparmor file fns and data to indicate use")
Signed-off-by: John Johansen <john.johansen@canonical.com>
In file included from security/apparmor/ipc.c:23:0:
security/apparmor/include/sig_names.h:26:3: error: 'SIGSTKFLT' undeclared here (not in a function)
[SIGSTKFLT] = 16, /* -, 16, - */
^
security/apparmor/include/sig_names.h:26:3: error: array index in initializer not of integer type
security/apparmor/include/sig_names.h:26:3: note: (near initialization for 'sig_map')
security/apparmor/include/sig_names.h:51:3: error: 'SIGUNUSED' undeclared here (not in a function)
[SIGUNUSED] = 34, /* -, 31, - */
^
security/apparmor/include/sig_names.h:51:3: error: array index in initializer not of integer type
security/apparmor/include/sig_names.h:51:3: note: (near initialization for 'sig_map')
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: c6bf1adaecaa ("apparmor: add the ability to mediate signals")
Signed-off-by: John Johansen <john.johansen@canonical.com>
sparse reports
poisoning the proxy->label before freeing the struct is resulting in
a sparse build warning.
../security/apparmor/label.c:52:30: warning: incorrect type in assignment (different address spaces)
../security/apparmor/label.c:52:30: expected struct aa_label [noderef] <asn:4>*label
../security/apparmor/label.c:52:30: got struct aa_label *<noident>
fix with RCU_INIT_POINTER as this is one of those cases where
rcu_assign_pointer() is not needed.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Generally unconfined has early bailout tests and does not need the
dfas initialized, however if an early bailout test is ever missed
it will result in an oops.
Be defensive and initialize the unconfined profile to have null dfas
(no permission) so if an early bailout test is missed we fail
closed (no perms granted) instead of oopsing.
Signed-off-by: John Johansen <john.johansen@canonical.com>
There is a race when null- profile is being created between the
initial lookup/creation of the profile and lock/addition of the
profile. This could result in multiple version of a profile being
added to the list which need to be removed/replaced.
Since these are learning profile their is no affect on mediation.
Signed-off-by: John Johansen <john.johansen@canonical.com>
new_null_profile will need to use some of the profile lookup fns()
so move instead of doing forward fn declarations.
Signed-off-by: John Johansen <john.johansen@canonical.com>
