The PKCS#7 test key type should use the secondary keyring instead of the
built-in keyring if available as the source of trustworthy keys.
Signed-off-by: David Howells <dhowells@redhat.com>
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>
Make the system trusted keyring depend on the asymmetric key type as
there's not a lot of point having it if you can't then load asymmetric keys
onto it.
This requires the ASYMMETRIC_KEY_TYPE to be made a bool, not a tristate, as
the Kconfig language doesn't then correctly force ASYMMETRIC_KEY_TYPE to
'y' rather than 'm' if SYSTEM_TRUSTED_KEYRING is 'y'.
Making SYSTEM_TRUSTED_KEYRING *select* ASYMMETRIC_KEY_TYPE instead doesn't
work as the Kconfig interpreter then wrongly complains about dependency
loops.
Signed-off-by: David Howells <dhowells@redhat.com>
We should call verify_signature() rather than directly calling
public_key_verify_signature() if we have a struct key to use as we
shouldn't be poking around in the private data of the key struct as that's
subtype dependent.
Signed-off-by: David Howells <dhowells@redhat.com>
Generalise x509_request_asymmetric_key(). It doesn't really have any
dependencies on X.509 features as it uses generalised IDs and the
public_key structs that contain data extracted from X.509.
Signed-off-by: David Howells <dhowells@redhat.com>
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>
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>
There's a bug in the code determining whether a certificate is self-signed
or not: if they have neither AKID nor SKID then we just assume that the
cert is self-signed, which may not be true.
Fix this by checking that the raw subject name matches the raw issuer name
and that the public key algorithm for the key and signature are both the
same in addition to requiring that the AKID bits match.
Signed-off-by: David Howells <dhowells@redhat.com>
Extract the signature digest for an X.509 certificate earlier, at the end
of x509_cert_parse() rather than leaving it to the callers thereof since it
has to be called anyway.
Further, immediately after that, check the signature on self-signed
certificates, also rather in the callers of x509_cert_parse().
We note in the x509_certificate struct the following bits of information:
(1) Whether the signature is self-signed (even if we can't check the
signature due to missing crypto).
(2) Whether the key held in the certificate needs unsupported crypto to be
used. We may get a PKCS#7 message with X.509 certs that we can't make
use of - we just ignore them and give ENOPKG at the end it we couldn't
verify anything if at least one of these unusable certs are in the
chain of trust.
(3) Whether the signature held in the certificate needs unsupported crypto
to be checked. We can still use the key held in this certificate,
even if we can't check the signature on it - if it is held in the
system trusted keyring, for instance. We just can't add it to a ring
of trusted keys or follow it further up the chain of trust.
Making these checks earlier allows x509_check_signature() to be removed and
replaced with direct calls to public_key_verify_signature().
Signed-off-by: David Howells <dhowells@redhat.com>
Point to the public_key_signature struct from the pkcs7_signed_info struct
rather than embedding it. This makes the code consistent with the X.509
signature handling and makes it possible to have a common cleanup function.
We also save a copy of the digest in the signature without sharing the
memory with the crypto layer metadata.
Signed-off-by: David Howells <dhowells@redhat.com>
Retain the key verification data (ie. the struct public_key_signature)
including the digest and the key identifiers.
Note that this means that we need to take a separate copy of the digest in
x509_get_sig_params() rather than lumping it in with the crypto layer data.
Signed-off-by: David Howells <dhowells@redhat.com>
Add key identifier pointers to public_key_signature struct so that they can
be used to retain the identifier of the key to be used to verify the
signature in both PKCS#7 and X.509.
Signed-off-by: David Howells <dhowells@redhat.com>
Allow authentication data to be stored in an asymmetric key in the 4th
element of the key payload and provide a way for it to be destroyed.
For the public key subtype, this will be a public_key_signature struct.
Signed-off-by: David Howells <dhowells@redhat.com>
Pull crypto fix from Herbert Xu:
"This fixes a bug in pkcs7_validate_trust and its users where the
output value may in fact be taken from uninitialised memory"
* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
PKCS#7: pkcs7_validate_trust(): initialize the _trusted output argument
Despite what the DocBook comment to pkcs7_validate_trust() says, the
*_trusted argument is never set to false.
pkcs7_validate_trust() only positively sets *_trusted upon encountering
a trusted PKCS#7 SignedInfo block.
This is quite unfortunate since its callers, system_verify_data() for
example, depend on pkcs7_validate_trust() clearing *_trusted on non-trust.
Indeed, UBSAN splats when attempting to load the uninitialized local
variable 'trusted' from system_verify_data() in pkcs7_validate_trust():
UBSAN: Undefined behaviour in crypto/asymmetric_keys/pkcs7_trust.c:194:14
load of value 82 is not a valid value for type '_Bool'
[...]
Call Trace:
[<ffffffff818c4d35>] dump_stack+0xbc/0x117
[<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169
[<ffffffff8194113b>] ubsan_epilogue+0xd/0x4e
[<ffffffff819419fa>] __ubsan_handle_load_invalid_value+0x111/0x158
[<ffffffff819418e9>] ? val_to_string.constprop.12+0xcf/0xcf
[<ffffffff818334a4>] ? x509_request_asymmetric_key+0x114/0x370
[<ffffffff814b83f0>] ? kfree+0x220/0x370
[<ffffffff818312c2>] ? public_key_verify_signature_2+0x32/0x50
[<ffffffff81835e04>] pkcs7_validate_trust+0x524/0x5f0
[<ffffffff813c391a>] system_verify_data+0xca/0x170
[<ffffffff813c3850>] ? top_trace_array+0x9b/0x9b
[<ffffffff81510b29>] ? __vfs_read+0x279/0x3d0
[<ffffffff8129372f>] mod_verify_sig+0x1ff/0x290
[...]
The implication is that pkcs7_validate_trust() effectively grants trust
when it really shouldn't have.
Fix this by explicitly setting *_trusted to false at the very beginning
of pkcs7_validate_trust().
Cc: <stable@vger.kernel.org>
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Move the RSA EMSA-PKCS1-v1_5 encoding from the asymmetric-key public_key
subtype to the rsa crypto module's pkcs1pad template. This means that the
public_key subtype no longer has any dependencies on public key type.
To make this work, the following changes have been made:
(1) The rsa pkcs1pad template is now used for RSA keys. This strips off the
padding and returns just the message hash.
(2) In a previous patch, the pkcs1pad template gained an optional second
parameter that, if given, specifies the hash used. We now give this,
and pkcs1pad checks the encoded message E(M) for the EMSA-PKCS1-v1_5
encoding and verifies that the correct digest OID is present.
(3) The crypto driver in crypto/asymmetric_keys/rsa.c is now reduced to
something that doesn't care about what the encryption actually does
and and has been merged into public_key.c.
(4) CONFIG_PUBLIC_KEY_ALGO_RSA is gone. Module signing must set
CONFIG_CRYPTO_RSA=y instead.
Thoughts:
(*) Should the encoding style (eg. raw, EMSA-PKCS1-v1_5) also be passed to
the padding template? Should there be multiple padding templates
registered that share most of the code?
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
The ASN.1 GeneralizedTime object carries an ISO 8601 format date and time.
The time is permitted to show midnight as 00:00 or 24:00 (the latter being
equivalent of 00:00 of the following day).
The permitted value is checked in x509_decode_time() but the actual
handling is left to mktime64().
Without this patch, certain X.509 certificates will be rejected and could
lead to an unbootable kernel.
Note that with this patch we also permit any 24:mm:ss time and extend this
to UTCTime, which whilst not strictly correct don't permit much leeway in
fiddling date strings.
Reported-by: Rudolf Polzer <rpolzer@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
cc: David Woodhouse <David.Woodhouse@intel.com>
cc: John Stultz <john.stultz@linaro.org>
The format of ASN.1 GeneralizedTime seems to be specified by ISO 8601
[X.680 46.3] and this apparently supports leap seconds (ie. the seconds
field is 60). It's not entirely clear that ASN.1 expects it, but we can
relax the seconds check slightly for GeneralizedTime.
This results in us passing a time with sec as 60 to mktime64(), which
handles it as being a duplicate of the 0th second of the next minute.
We can't really do otherwise without giving the kernel much greater
knowledge of where all the leap seconds are. Unfortunately, this would
require change the mapping of the kernel's current-time-in-seconds.
UTCTime, however, only supports a seconds value in the range 00-59, but for
the sake of simplicity allow this with UTCTime also.
Without this patch, certain X.509 certificates will be rejected,
potentially making a kernel unbootable.
Reported-by: Rudolf Polzer <rpolzer@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
cc: David Woodhouse <David.Woodhouse@intel.com>
cc: John Stultz <john.stultz@linaro.org>
There are still a couple of minor issues in the X.509 leap year handling:
(1) To avoid doing a modulus-by-400 in addition to a modulus-by-100 when
determining whether the year is a leap year or not, I divided the year
by 100 after doing the modulus-by-100, thereby letting the compiler do
one instruction for both, and then did a modulus-by-4.
Unfortunately, I then passed the now-modified year value to mktime64()
to construct a time value.
Since this isn't a fast path and since mktime64() does a bunch of
divisions, just condense down to "% 400". It's also easier to read.
(2) The default month length for any February where the year doesn't
divide by four exactly is obtained from the month_length[] array where
the value is 29, not 28.
This is fixed by altering the table.
Reported-by: Rudolf Polzer <rpolzer@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
cc: stable@vger.kernel.org
The boolean want is not initialized and hence garbage. The default should
be false (later it is only set to true on tne sinfo->authattrs check).
Found with static analysis using CoverityScan
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David Howells <dhowells@redhat.com>
David Howells
Linus Torvalds
Nicolai Stange
Colin Ian King
Tadeusz Struk