Keyrings Archive on lore.kernel.org
 help / color / Atom feed
From: David Howells <dhowells@redhat.com>
To: torvalds@linux-foundation.org
Cc: dhowells@redhat.com, jarkko.sakkinen@linux.intel.com,
	longman@redhat.com, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [GIT PULL] keys: Fix key->sem vs mmap_sem issue when reading key
Date: Mon, 30 Mar 2020 12:16:38 +0000
Message-ID: <1437197.1585570598@warthog.procyon.org.uk> (raw)

Hi Linus,

Here's a couple of patches that fix a circular dependency between holding
key->sem and mm->mmap_sem when reading data from a key.  One potential
issue is that a filesystem looking to use a key inside, say, ->readpages()
could deadlock if the key being read is the key that's required and the
buffer the key is being read into is on a page that needs to be fetched.

The case actually detected is a bit more involved - with a filesystem
calling request_key() and locking the target keyring for write - which
could be being read.

[Note: kbuild spotted a compiler(?) warning that I've not seen before,
 complaining "The scope of the variable 'oldxdr' can be reduced.
 [variableScope]".  It's unhappy that a variable that's declared at the top
 of the function hasn't been moved into an interior for-loop.  Is this
 something we're now requiring?  Anyway, I'd prefer to fix that with a
 follow up patch through the net tree rather than go for a 9th iteration on
 these patches.]

Thanks,
David
---
The following changes since commit 1b649e0bcae71c118c1333e02249a7510ba7f70a:

  Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net (2020-03-25 13:58:05 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git tags/keys-fixes-20200329

for you to fetch changes up to 4f0882491a148059a52480e753b7f07fc550e188:

  KEYS: Avoid false positive ENOMEM error on key read (2020-03-29 12:40:41 +0100)

----------------------------------------------------------------
Keyrings fixes

----------------------------------------------------------------
Waiman Long (2):
      KEYS: Don't write out to userspace while holding key semaphore
      KEYS: Avoid false positive ENOMEM error on key read

 include/keys/big_key-type.h               |   2 +-
 include/keys/user-type.h                  |   3 +-
 include/linux/key-type.h                  |   2 +-
 net/dns_resolver/dns_key.c                |   2 +-
 net/rxrpc/key.c                           |  27 +++-----
 security/keys/big_key.c                   |  11 ++--
 security/keys/encrypted-keys/encrypted.c  |   7 +-
 security/keys/internal.h                  |  12 ++++
 security/keys/keyctl.c                    | 103 +++++++++++++++++++++++++-----
 security/keys/keyring.c                   |   6 +-
 security/keys/request_key_auth.c          |   7 +-
 security/keys/trusted-keys/trusted_tpm1.c |  14 +---
 security/keys/user_defined.c              |   5 +-
 13 files changed, 126 insertions(+), 75 deletions(-)

             reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-30 12:16 David Howells [this message]
2020-04-04 20:00 ` Linus Torvalds
2020-04-05  3:10   ` Waiman Long
2020-04-05  9:03   ` David Howells
2020-04-05 17:31     ` Linus Torvalds
2020-04-06  2:38       ` Waiman Long
2020-04-04 20:05 ` pr-tracker-bot

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=1437197.1585570598@warthog.procyon.org.uk \
    --to=dhowells@redhat.com \
    --cc=jarkko.sakkinen@linux.intel.com \
    --cc=keyrings@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=longman@redhat.com \
    --cc=torvalds@linux-foundation.org \
    /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

Keyrings Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/keyrings/0 keyrings/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 keyrings keyrings/ https://lore.kernel.org/keyrings \
		keyrings@vger.kernel.org
	public-inbox-index keyrings

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.keyrings


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git