From: "Mickaël Salaün" <mic@digikod.net>
To: Jarkko Sakkinen <jarkko@kernel.org>
Cc: "David Howells" <dhowells@redhat.com>,
"David Woodhouse" <dwmw2@infradead.org>,
"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>,
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,
"Mimi Zohar" <zohar@linux.vnet.ibm.com>
Subject: Re: [PATCH v3 04/10] certs: Fix blacklist flag type confusion
Date: Wed, 20 Jan 2021 12:15:10 +0100 [thread overview]
Message-ID: <fc4d5812-238c-baf7-d7f6-cc123bdb855d@digikod.net> (raw)
In-Reply-To: <YAepvxOBcEU0paqA@kernel.org>
On 20/01/2021 04:55, Jarkko Sakkinen wrote:
> On Thu, Jan 14, 2021 at 04:19:03PM +0100, Mickaël Salaün wrote:
>> From: David Howells <dhowells@redhat.com>
>>
>> KEY_FLAG_KEEP is not meant to be passed to keyring_alloc() or key_alloc(),
>> as these only take KEY_ALLOC_* flags. KEY_FLAG_KEEP has the same value as
>> KEY_ALLOC_BYPASS_RESTRICTION, but fortunately only key_create_or_update()
>> uses it. LSMs using the key_alloc hook don't check that flag.
>>
>> KEY_FLAG_KEEP is then ignored but fortunately (again) the root user cannot
>> write to the blacklist keyring, so it is not possible to remove a key/hash
>> from it.
>>
>> Fix this by adding a KEY_ALLOC_SET_KEEP flag that tells key_alloc() to set
>> KEY_FLAG_KEEP on the new key. blacklist_init() can then, correctly, pass
>> this to keyring_alloc().
>
> OK, so thing work by luck now, but given the new patches which allow
> to append new keys they would break, right?
Without this fix, patch 9/10 would allow to remove and modify keys from
the blacklist keyring.
>
>> We can also use this in ima_mok_init() rather than setting the flag
>> manually.
>
> What does ima_mok_init() do?
This was initially an addition from David Howells, I only fixed the
argument bit-ORing. ima_mok_init() allocates a blacklist keyring (with
different properties) dedicated to IMA.
>> Note that this doesn't fix an observable bug with the current
>> implementation but it is required to allow addition of new hashes to the
>> blacklist in the future without making it possible for them to be removed.
>>
>> Fixes: 734114f8782f ("KEYS: Add a system blacklist keyring")
>> cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
>
> Nit: Cc
OK
>
>> Cc: David Woodhouse <dwmw2@infradead.org>
>> Reported-by: Mickaël Salaün <mic@linux.microsoft.com>
>> Signed-off-by: David Howells <dhowells@redhat.com>
>> [mic@linux.microsoft.com: fix ima_mok_init()]
>> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
>> ---
>>
>> Changes since v2:
>> * Cherry-pick rewritten v1 patch from
>> https://lore.kernel.org/lkml/2659836.1607940186@warthog.procyon.org.uk/
>> to rebase on v5.11-rc3 and fix ima_mok_init().
>> ---
>> certs/blacklist.c | 2 +-
>> include/linux/key.h | 1 +
>> security/integrity/ima/ima_mok.c | 4 +---
>> security/keys/key.c | 2 ++
>> 4 files changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/certs/blacklist.c b/certs/blacklist.c
>> index a888b934a1cd..029471947838 100644
>> --- a/certs/blacklist.c
>> +++ b/certs/blacklist.c
>> @@ -162,7 +162,7 @@ static int __init blacklist_init(void)
>> KEY_USR_VIEW | KEY_USR_READ |
>> KEY_USR_SEARCH,
>> KEY_ALLOC_NOT_IN_QUOTA |
>> - KEY_FLAG_KEEP,
>> + KEY_ALLOC_SET_KEEP,
>> NULL, NULL);
>> if (IS_ERR(blacklist_keyring))
>> panic("Can't allocate system blacklist keyring\n");
>> diff --git a/include/linux/key.h b/include/linux/key.h
>> index 0f2e24f13c2b..eed3ce139a32 100644
>> --- a/include/linux/key.h
>> +++ b/include/linux/key.h
>> @@ -289,6 +289,7 @@ extern struct key *key_alloc(struct key_type *type,
>> #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
>> #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
>> #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
>> +#define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */
>>
>> extern void key_revoke(struct key *key);
>> extern void key_invalidate(struct key *key);
>> diff --git a/security/integrity/ima/ima_mok.c b/security/integrity/ima/ima_mok.c
>> index 36cadadbfba4..5594dd38ab04 100644
>> --- a/security/integrity/ima/ima_mok.c
>> +++ b/security/integrity/ima/ima_mok.c
>> @@ -38,13 +38,11 @@ __init int ima_mok_init(void)
>> (KEY_POS_ALL & ~KEY_POS_SETATTR) |
>> KEY_USR_VIEW | KEY_USR_READ |
>> KEY_USR_WRITE | KEY_USR_SEARCH,
>> - KEY_ALLOC_NOT_IN_QUOTA,
>> + KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_SET_KEEP,
>> restriction, NULL);
>>
>> if (IS_ERR(ima_blacklist_keyring))
>> panic("Can't allocate IMA blacklist keyring.");
>> -
>> - set_bit(KEY_FLAG_KEEP, &ima_blacklist_keyring->flags);
>> return 0;
>> }
>> device_initcall(ima_mok_init);
>> diff --git a/security/keys/key.c b/security/keys/key.c
>> index ebe752b137aa..c45afdd1dfbb 100644
>> --- a/security/keys/key.c
>> +++ b/security/keys/key.c
>> @@ -303,6 +303,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
>> key->flags |= 1 << KEY_FLAG_BUILTIN;
>> if (flags & KEY_ALLOC_UID_KEYRING)
>> key->flags |= 1 << KEY_FLAG_UID_KEYRING;
>> + if (flags & KEY_ALLOC_SET_KEEP)
>> + key->flags |= 1 << KEY_FLAG_KEEP;
>>
>> #ifdef KEY_DEBUGGING
>> key->magic = KEY_DEBUG_MAGIC;
>> --
>> 2.30.0
>>
>
> Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
>
> /Jarkko
>
next prev parent reply other threads:[~2021-01-20 12:40 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-14 15:18 [PATCH v3 00/10] Enable root to update the blacklist keyring Mickaël Salaün
2021-01-14 15:19 ` [PATCH v3 01/10] certs/blacklist: fix kernel doc interface issue Mickaël Salaün
2021-01-20 3:39 ` Jarkko Sakkinen
2021-01-14 15:19 ` [PATCH v3 02/10] certs: Fix blacklisted hexadecimal hash string check Mickaël Salaün
2021-01-20 3:43 ` Jarkko Sakkinen
2021-01-20 11:12 ` Mickaël Salaün
2021-01-20 23:44 ` Jarkko Sakkinen
2021-01-14 15:19 ` [PATCH v3 03/10] PKCS#7: Fix missing include Mickaël Salaün
2021-01-20 3:44 ` Jarkko Sakkinen
2021-01-14 15:19 ` [PATCH v3 04/10] certs: Fix blacklist flag type confusion Mickaël Salaün
2021-01-20 3:55 ` Jarkko Sakkinen
2021-01-20 11:15 ` Mickaël Salaün [this message]
2021-01-20 23:45 ` Jarkko Sakkinen
2021-01-14 15:19 ` [PATCH v3 05/10] certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID Mickaël Salaün
2021-01-20 5:15 ` Jarkko Sakkinen
2021-01-20 11:17 ` Mickaël Salaün
2021-01-20 23:48 ` Jarkko Sakkinen
2021-01-14 15:19 ` [PATCH v3 06/10] certs: Make blacklist_vet_description() more strict Mickaël Salaün
2021-01-20 4:16 ` Jarkko Sakkinen
2021-01-20 11:23 ` Mickaël Salaün
2021-01-14 15:19 ` [PATCH v3 07/10] certs: Factor out the blacklist hash creation Mickaël Salaün
2021-01-14 15:19 ` [PATCH v3 08/10] certs: Check that builtin blacklist hashes are valid Mickaël Salaün
2021-01-20 5:19 ` Jarkko Sakkinen
2021-01-20 11:57 ` Mickaël Salaün
2021-01-20 23:53 ` Jarkko Sakkinen
2021-01-21 9:18 ` Mickaël Salaün
2021-01-21 15:21 ` Jarkko Sakkinen
2021-01-14 15:19 ` [PATCH v3 09/10] certs: Allow root user to append signed hashes to the blacklist keyring Mickaël Salaün
2021-01-15 13:06 ` Mimi Zohar
2021-01-20 5:23 ` Jarkko Sakkinen
2021-01-20 11:24 ` Mickaël Salaün
2021-01-14 15:19 ` [PATCH v3 10/10] tools/certs: Add print-cert-tbs-hash.sh Mickaël Salaün
2021-01-15 9:28 ` [PATCH v3 00/10] Enable root to update the blacklist keyring Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=fc4d5812-238c-baf7-d7f6-cc123bdb855d@digikod.net \
--to=mic@digikod.net \
--cc=davem@davemloft.net \
--cc=dhowells@redhat.com \
--cc=dwmw2@infradead.org \
--cc=herbert@gondor.apana.org.au \
--cc=jarkko@kernel.org \
--cc=jmorris@namei.org \
--cc=keyrings@vger.kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=mic@linux.microsoft.com \
--cc=serge@hallyn.com \
--cc=zohar@linux.ibm.com \
--cc=zohar@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).