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This patch allows the kexec_file_load syscall to verify the PE signed
kernel image signature based on the preboot keys stored in the .platform
keyring, as fall back, if the signature verification failed due to not
finding the public key in the secondary or builtin keyrings.
This commit adds a VERIFY_USE_PLATFORM_KEYRING similar to previous
VERIFY_USE_SECONDARY_KEYRING indicating that verify_pkcs7_signature
should verify the signature using platform keyring. Also, decrease
the error message log level when verification failed with -ENOKEY,
so that if called tried multiple time with different keyring it
won't generate extra noises.
Signed-off-by: Kairui Song <kasong@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com> (for kexec_file_load part)
[zohar@linux.ibm.com: tweaked the first paragraph of the patch description,
and fixed checkpatch warning.]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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commit 9dc92c45177a ("integrity: Define a trusted platform keyring")
introduced a .platform keyring for storing preboot keys, used for
verifying kernel image signatures. Currently only IMA-appraisal is able
to use the keyring to verify kernel images that have their signature
stored in xattr.
This patch exposes the .platform keyring, making it accessible for
verifying PE signed kernel images as well.
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Kairui Song <kasong@redhat.com>
Cc: David Howells <dhowells@redhat.com>
[zohar@linux.ibm.com: fixed checkpatch errors, squashed with patch fix]
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
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Replace the use of a magic number that indicates that verify_*_signature()
should use the secondary keyring with a symbol.
Signed-off-by: Yannik Sembritzki <yannik@sembritzki.me>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: keyrings@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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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>
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The first argument to the restrict_link_func_t functions was a keyring
pointer. These functions are called by the key subsystem with this
argument set to the destination keyring, but restrict_link_by_signature
expects a pointer to the relevant trusted keyring.
Restrict functions may need something other than a single struct key
pointer to allow or reject key linkage, so the data used to make that
decision (such as the trust keyring) is moved to a new, fourth
argument. The first argument is now always the destination keyring.
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
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Add a secondary system keyring that can be added to by root whilst the
system is running - provided the key being added is vouched for by a key
built into the kernel or already added to the secondary keyring.
Rename .system_keyring to .builtin_trusted_keys to distinguish it more
obviously from the new keyring (called .secondary_trusted_keys).
The new keyring needs to be enabled with CONFIG_SECONDARY_TRUSTED_KEYRING.
If the secondary keyring is enabled, a link is created from that to
.builtin_trusted_keys so that the the latter will automatically be searched
too if the secondary keyring is searched.
Signed-off-by: David Howells <dhowells@redhat.com>
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Remove KEY_FLAG_TRUSTED and KEY_ALLOC_TRUSTED as they're no longer
meaningful. Also we can drop the trusted flag from the preparse structure.
Given this, we no longer need to pass the key flags through to
restrict_link().
Further, we can now get rid of keyring_restrict_trusted_only() also.
Signed-off-by: David Howells <dhowells@redhat.com>
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Move the point at which a key is determined to be trustworthy to
__key_link() so that we use the contents of the keyring being linked in to
to determine whether the key being linked in is trusted or not.
What is 'trusted' then becomes a matter of what's in the keyring.
Currently, the test is done when the key is parsed, but given that at that
point we can only sensibly refer to the contents of the system trusted
keyring, we can only use that as the basis for working out the
trustworthiness of a new key.
With this change, a trusted keyring is a set of keys that once the
trusted-only flag is set cannot be added to except by verification through
one of the contained keys.
Further, adding a key into a trusted keyring, whilst it might grant
trustworthiness in the context of that keyring, does not automatically
grant trustworthiness in the context of a second keyring to which it could
be secondarily linked.
To accomplish this, the authentication data associated with the key source
must now be retained. For an X.509 cert, this means the contents of the
AuthorityKeyIdentifier and the signature data.
If system keyrings are disabled then restrict_link_by_builtin_trusted()
resolves to restrict_link_reject(). The integrity digital signature code
still works correctly with this as it was previously using
KEY_FLAG_TRUSTED_ONLY, which doesn't permit anything to be added if there
is no system keyring against which trust can be determined.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add a facility whereby proposed new links to be added to a keyring can be
vetted, permitting them to be rejected if necessary. This can be used to
block public keys from which the signature cannot be verified or for which
the signature verification fails. It could also be used to provide
blacklisting.
This affects operations like add_key(), KEYCTL_LINK and KEYCTL_INSTANTIATE.
To this end:
(1) A function pointer is added to the key struct that, if set, points to
the vetting function. This is called as:
int (*restrict_link)(struct key *keyring,
const struct key_type *key_type,
unsigned long key_flags,
const union key_payload *key_payload),
where 'keyring' will be the keyring being added to, key_type and
key_payload will describe the key being added and key_flags[*] can be
AND'ed with KEY_FLAG_TRUSTED.
[*] This parameter will be removed in a later patch when
KEY_FLAG_TRUSTED is removed.
The function should return 0 to allow the link to take place or an
error (typically -ENOKEY, -ENOPKG or -EKEYREJECTED) to reject the
link.
The pointer should not be set directly, but rather should be set
through keyring_alloc().
Note that if called during add_key(), preparse is called before this
method, but a key isn't actually allocated until after this function
is called.
(2) KEY_ALLOC_BYPASS_RESTRICTION is added. This can be passed to
key_create_or_update() or key_instantiate_and_link() to bypass the
restriction check.
(3) KEY_FLAG_TRUSTED_ONLY is removed. The entire contents of a keyring
with this restriction emplaced can be considered 'trustworthy' by
virtue of being in the keyring when that keyring is consulted.
(4) key_alloc() and keyring_alloc() take an extra argument that will be
used to set restrict_link in the new key. This ensures that the
pointer is set before the key is published, thus preventing a window
of unrestrictedness. Normally this argument will be NULL.
(5) As a temporary affair, keyring_restrict_trusted_only() is added. It
should be passed to keyring_alloc() as the extra argument instead of
setting KEY_FLAG_TRUSTED_ONLY on a keyring. This will be replaced in
a later patch with functions that look in the appropriate places for
authoritative keys.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
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Make the determination of the trustworthiness of a key dependent on whether
a key that can verify it is present in the supplied ring of trusted keys
rather than whether or not the verifying key has KEY_FLAG_TRUSTED set.
verify_pkcs7_signature() will return -ENOKEY if the PKCS#7 message trust
chain cannot be verified.
Signed-off-by: David Howells <dhowells@redhat.com>
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Generalise system_verify_data() to provide access to internal content
through a callback. This allows all the PKCS#7 stuff to be hidden inside
this function and removed from the PE file parser and the PKCS#7 test key.
If external content is not required, NULL should be passed as data to the
function. If the callback is not required, that can be set to NULL.
The function is now called verify_pkcs7_signature() to contrast with
verify_pefile_signature() and the definitions of both have been moved into
linux/verification.h along with the key_being_used_for enum.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add KEY_ALLOC_BUILT_IN to convey that a key should have KEY_FLAG_BUILTIN
set rather than setting it after the fact.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
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Move certificate handling out of the kernel/ directory and into a certs/
directory to get all the weird stuff in one place and move the generated
signing keys into this directory.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>
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Kairui Song
Yannik Sembritzki
Mat Martineau
David Howells