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From: "Mickaël Salaün" <mic@digikod.net>
To: David Howells <dhowells@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Jarkko Sakkinen <jarkko@kernel.org>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"David S . Miller" <davem@davemloft.net>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"James Morris" <jmorris@namei.org>,
	"Mickaël Salaün" <mic@linux.microsoft.com>,
	"Mimi Zohar" <zohar@linux.ibm.com>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	"Tyler Hicks" <tyhicks@linux.microsoft.com>,
	keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	"Ben Boeckel" <mathstuf@gmail.com>
Subject: [PATCH v4 03/10] certs: Fix blacklisted hexadecimal hash string check
Date: Thu, 21 Jan 2021 16:55:06 +0100
Message-ID: <20210121155513.539519-4-mic@digikod.net> (raw)
In-Reply-To: <20210121155513.539519-1-mic@digikod.net>

From: Mickaël Salaün <mic@linux.microsoft.com>

When looking for a blacklisted hash, bin2hex() is used to transform a
binary hash to an ascii (lowercase) hexadecimal string.  This string is
then search for in the description of the keys from the blacklist
keyring.  When adding a key to the blacklist keyring,
blacklist_vet_description() checks the hash prefix and the hexadecimal
string, but not that this string is lowercase.  It is then valid to set
hashes with uppercase hexadecimal, which will be silently ignored by the
kernel.

Add an additional check to blacklist_vet_description() to check that
hexadecimal strings are in lowercase.

Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Ben Boeckel <mathstuf@gmail.com>
---

Changes since v2:
* Cherry-pick v1 patch from
  https://lore.kernel.org/lkml/2659836.1607940186@warthog.procyon.org.uk/
  to rebase on v5.11-rc3.
* Rearrange Cc order.
---
 certs/blacklist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/certs/blacklist.c b/certs/blacklist.c
index 6514f9ebc943..4e1a58170d5c 100644
--- a/certs/blacklist.c
+++ b/certs/blacklist.c
@@ -37,7 +37,7 @@ static int blacklist_vet_description(const char *desc)
 found_colon:
 	desc++;
 	for (; *desc; desc++) {
-		if (!isxdigit(*desc))
+		if (!isxdigit(*desc) || isupper(*desc))
 			return -EINVAL;
 		n++;
 	}
-- 
2.30.0


  parent reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-21 15:55 [PATCH v4 00/10] Enable root to update the blacklist keyring Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 01/10] tools/certs: Add print-cert-tbs-hash.sh Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 02/10] certs: Check that builtin blacklist hashes are valid Mickaël Salaün
2021-01-21 15:55 ` Mickaël Salaün [this message]
2021-01-21 15:55 ` [PATCH v4 04/10] certs: Fix blacklist flag type confusion Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 05/10] certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 06/10] certs: Make blacklist_vet_description() more strict Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 07/10] certs/blacklist: fix kernel doc interface issue Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 08/10] certs: Factor out the blacklist hash creation Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 09/10] PKCS#7: Fix missing include Mickaël Salaün
2021-01-21 15:55 ` [PATCH v4 10/10] certs: Allow root user to append signed hashes to the blacklist keyring Mickaël Salaün
2021-01-28 16:52 ` [PATCH v4 00/10] Enable root to update " David Howells
2021-01-28 17:38   ` Mickaël Salaün
2021-01-28 18:00     ` Mickaël Salaün
2021-01-30 19:39   ` Jarkko Sakkinen

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