linux-kernel - [PATCH v1 1/9] certs: Fix blacklisted hexadecimal hash string check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20201120180426.922572-2-mic@digikod.net>
Date:   Fri, 20 Nov 2020 19:04:18 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     David Howells <dhowells@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     Mickaël Salaün <mic@...ikod.net>,
        "David S . Miller" <davem@...emloft.net>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        James Morris <jmorris@...ei.org>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Mickaël Salaün <mic@...ux.microsoft.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        "Serge E . Hallyn" <serge@...lyn.com>, keyrings@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: [PATCH v1 1/9] certs: Fix blacklisted hexadecimal hash string check

From: Mickaël Salaün <mic@...ux.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 Howells <dhowells@...hat.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Signed-off-by: Mickaël Salaün <mic@...ux.microsoft.com>
---
 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++;
 	}
-- 
2.29.2