unimore/kernel-hacking-2024-linux-steffo
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Eric Biggers 971b42c038 PKCS#7: fix certificate chain verification 
When pkcs7_verify_sig_chain() is building the certificate chain for a
SignerInfo using the certificates in the PKCS#7 message, it is passing
the wrong arguments to public_key_verify_signature().  Consequently,
when the next certificate is supposed to be used to verify the previous
certificate, the next certificate is actually used to verify itself.

An attacker can use this bug to create a bogus certificate chain that
has no cryptographic relationship between the beginning and end.

Fortunately I couldn't quite find a way to use this to bypass the
overall signature verification, though it comes very close.  Here's the
reasoning: due to the bug, every certificate in the chain beyond the
first actually has to be self-signed (where "self-signed" here refers to
the actual key and signature; an attacker might still manipulate the
certificate fields such that the self_signed flag doesn't actually get
set, and thus the chain doesn't end immediately).  But to pass trust
validation (pkcs7_validate_trust()), either the SignerInfo or one of the
certificates has to actually be signed by a trusted key.  Since only
self-signed certificates can be added to the chain, the only way for an
attacker to introduce a trusted signature is to include a self-signed
trusted certificate.

But, when pkcs7_validate_trust_one() reaches that certificate, instead
of trying to verify the signature on that certificate, it will actually
look up the corresponding trusted key, which will succeed, and then try
to verify the *previous* certificate, which will fail.  Thus, disaster
is narrowly averted (as far as I could tell).

Fixes: 6c2dc5ae4a ("X.509: Extract signature digest and make self-signed cert checks earlier")
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2018-02-22 14:38:33 +00:00
..
asymmetric_keys PKCS#7: fix certificate chain verification 2018-02-22 14:38:33 +00:00
async_tx License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
.gitignore
842.c
ablk_helper.c crypto: remove unused hardirq.h 2017-11-29 17:33:29 +11:00
ablkcipher.c
acompress.c
aead.c crypto: aead - prevent using AEADs without setting key 2018-01-12 23:03:39 +11:00
aes_generic.c
aes_ti.c
af_alg.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ahash.c crypto: hash - prevent using keyed hashes without setting key 2018-01-12 23:03:37 +11:00
akcipher.c
algapi.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-31 14:22:45 -08:00
algboss.c crypto: algboss - remove redundant setting of len to zero 2017-10-07 12:10:34 +08:00
algif_aead.c crypto: aead - prevent using AEADs without setting key 2018-01-12 23:03:39 +11:00
algif_hash.c crypto: hash - prevent using keyed hashes without setting key 2018-01-12 23:03:37 +11:00
algif_rng.c
algif_skcipher.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-31 14:22:45 -08:00
ansi_cprng.c
anubis.c
api.c crypto: algapi - convert cra_refcnt to refcount_t 2018-01-05 18:43:09 +11:00
arc4.c
authenc.c crypto: null - Get rid of crypto_{get,put}_default_null_skcipher2() 2017-12-22 19:29:08 +11:00
authencesn.c crypto: null - Get rid of crypto_{get,put}_default_null_skcipher2() 2017-12-22 19:29:08 +11:00
blkcipher.c crypto: remove unused hardirq.h 2017-11-29 17:33:29 +11:00
blowfish_common.c
blowfish_generic.c
camellia_generic.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
cast5_generic.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
cast6_generic.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
cast_common.c
cbc.c
ccm.c crypto: ccm - preserve the IV buffer 2017-11-03 21:35:35 +08:00
chacha20_generic.c crypto: chacha20 - Fix keystream alignment for chacha20_block() 2017-11-29 17:33:33 +11:00
chacha20poly1305.c crypto: chacha20poly1305 - validate the digest size 2017-12-22 19:02:33 +11:00
cipher.c
cmac.c
compress.c
crc32_generic.c crypto: hash - annotate algorithms taking optional key 2018-01-12 23:03:35 +11:00
crc32c_generic.c crypto: hash - annotate algorithms taking optional key 2018-01-12 23:03:35 +11:00
crct10dif_common.c
crct10dif_generic.c
cryptd.c crypto: hash - annotate algorithms taking optional key 2018-01-12 23:03:35 +11:00
crypto_engine.c
crypto_null.c
crypto_user.c crypto: algapi - convert cra_refcnt to refcount_t 2018-01-05 18:43:09 +11:00
crypto_wq.c
ctr.c crypto: algapi - make crypto_xor() take separate dst and src arguments 2017-08-04 09:27:15 +08:00
cts.c crypto: remove redundant backlog checks on EBUSY 2017-11-03 22:11:17 +08:00
deflate.c
des_generic.c
dh.c crypto: dh - Remove pointless checks for NULL 'p' and 'g' 2017-11-10 19:20:22 +08:00
dh_helper.c crypto: dh - Don't permit 'key' or 'g' size longer than 'p' 2017-11-10 19:20:17 +08:00
drbg.c crypto: drbg - move to generic async completion 2017-11-03 22:11:19 +08:00
ecb.c
ecc.c crypto: ecc - Fix NULL pointer deref. on no default_rng 2017-11-29 17:33:24 +11:00
ecc.h
ecc_curve_defs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
ecdh.c crypto: ecdh - remove empty exit() 2017-11-06 14:45:04 +08:00
ecdh_helper.c crypto: ecdh - return unsigned value for crypto_ecdh_key_len() 2017-10-12 22:55:00 +08:00
echainiv.c crypto: echainiv - Remove unused alg/spawn variable 2017-12-22 19:52:45 +11:00
fcrypt.c
fips.c
gcm.c crypto: null - Get rid of crypto_{get,put}_default_null_skcipher2() 2017-12-22 19:29:08 +11:00
gf128mul.c crypto: gf128mul - remove incorrect comment 2017-12-22 19:52:40 +11:00
ghash-generic.c crypto: ghash - remove checks for key being set 2018-01-12 23:03:38 +11:00
hash_info.c
hmac.c crypto: hmac - require that the underlying hash algorithm is unkeyed 2017-11-29 13:39:15 +11:00
internal.h crypto: algapi - remove unused notifications 2018-01-05 18:43:10 +11:00
jitterentropy-kcapi.c
jitterentropy.c
Kconfig Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-31 14:22:45 -08:00
keywrap.c crypto: keywrap - Add missing ULL suffixes for 64-bit constants 2017-11-29 17:33:26 +11:00
khazad.c
kpp.c
lrw.c crypto: remove redundant backlog checks on EBUSY 2017-11-03 22:11:17 +08:00
lz4.c
lz4hc.c
lzo.c
Makefile crypto: aes-generic - fix aes-generic regression on powerpc 2018-01-20 11:43:36 +11:00
mcryptd.c crypto: hash - annotate algorithms taking optional key 2018-01-12 23:03:35 +11:00
md4.c
md5.c
memneq.c
michael_mic.c
pcbc.c crypto: algapi - make crypto_xor() take separate dst and src arguments 2017-08-04 09:27:15 +08:00
pcrypt.c crypto: pcrypt - fix freeing pcrypt instances 2017-12-22 19:02:47 +11:00
poly1305_generic.c crypto: poly1305 - remove ->setkey() method 2018-01-12 23:03:14 +11:00
proc.c crypto: algapi - convert cra_refcnt to refcount_t 2018-01-05 18:43:09 +11:00
ripemd.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rmd128.c crypto: drop unnecessary return statements 2017-09-22 17:43:28 +08:00
rmd160.c crypto: drop unnecessary return statements 2017-09-22 17:43:28 +08:00
rmd256.c crypto: drop unnecessary return statements 2017-09-22 17:43:28 +08:00
rmd320.c crypto: drop unnecessary return statements 2017-09-22 17:43:28 +08:00
rng.c crypto: rng - ensure that the RNG is ready before using 2017-07-28 17:56:00 +08:00
rsa-pkcs1pad.c crypto: remove redundant backlog checks on EBUSY 2017-11-03 22:11:17 +08:00
rsa.c
rsa_helper.c crypto: rsa - fix buffer overread when stripping leading zeroes 2017-11-29 13:39:14 +11:00
rsaprivkey.asn1
rsapubkey.asn1
salsa20_generic.c crypto: salsa20 - export generic helpers 2018-01-12 23:03:42 +11:00
scatterwalk.c
scompress.c crypto: scompress - use sgl_alloc() and sgl_free() 2018-01-06 09:18:00 -07:00
seed.c
seqiv.c crypto: seqiv - Remove unused alg/spawn variable 2017-12-22 19:52:45 +11:00
serpent_generic.c crypto: serpent - improve __serpent_setkey with UBSAN 2017-08-09 20:17:54 +08:00
sha1_generic.c
sha3_generic.c crypto: sha3-generic - Use __optimize to support old compilers 2018-02-08 22:38:12 +11:00
sha256_generic.c
sha512_generic.c
shash.c crypto: hash - prevent using keyed hashes without setting key 2018-01-12 23:03:37 +11:00
simd.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
skcipher.c crypto: skcipher - prevent using skciphers without setting key 2018-01-12 23:03:39 +11:00
sm3_generic.c crypto: sm3 - add OSCCA SM3 secure hash 2017-09-22 17:43:07 +08:00
tcrypt.c crypto: tcrypt - free xoutbuf instead of axbuf 2018-01-12 23:03:07 +11:00
tcrypt.h
tea.c
testmgr.c crypto: testmgr - test misuse of result in ahash 2018-01-26 01:10:29 +11:00
testmgr.h crypto: testmgr - add new testcases for sha3 2018-01-26 01:10:34 +11:00
tgr192.c
twofish_common.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
twofish_generic.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
vmac.c
wp512.c
xcbc.c crypto: replace FSF address with web source in license notices 2017-11-29 17:33:25 +11:00
xor.c kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2017-11-15 18:21:04 -08:00
xts.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-14 10:52:09 -08:00