[[!meta title="Problems with root-owned gpg keyrings"]]
/var/lib/monkeysphere/gnupg-host/ is root-owned, and the public
keyring in that directory is controlled by the superuser.
We currently expect the monkeysphere user to read from (but not
write to) that keyring. But using a keyring in a directory that you
don't control appears to trigger a subtle bug in
gpg that has been unresolved for quite
a long time.
With some of the new error checking i'm doing in
monkeysphere-server, typical operations that involve both keyrings
as the non-privileged user can fail with an error message like:
gpg: failed to rebuild keyring cache: file open error
Running the relevant operation a second time as the same user usually
lets things go through without a failure, but this seems like it would
be hiding a bug, rather than getting it fixed correctly.
Are there other ways we can deal with this problem?
--dkg
Here is an example when using monkeysphere-server
add-identity-certifier on a host with a newly-installed monkeysphere
installaton. Note that running the same command a second time works
as expected:
0 pip:~# monkeysphere-server c+ 0EE5BE979282D80B9F7540F1CCD2ED94D21739E9
gpg: requesting key D21739E9 from hkp server pool.sks-keyservers.net
gpg: key D21739E9: public key "Daniel Kahn Gillmor <dkg@fifthhorseman.net>" imported
gpg: can't create `/var/lib/monkeysphere/gnupg-host/pubring.gpg.tmp': Permission denied
gpg: failed to rebuild keyring cache: file open error
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: next trustdb check due at 2009-03-30
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
Could not receive a key with this ID from the 'pool.sks-keyservers.net' keyserver.
255 pip:~# monkeysphere-server c+ 0EE5BE979282D80B9F7540F1CCD2ED94D21739E9
gpg: requesting key D21739E9 from hkp server pool.sks-keyservers.net
gpg: key D21739E9: "Daniel Kahn Gillmor <dkg@fifthhorseman.net>" not changed
gpg: Total number processed: 1
gpg: unchanged: 1
key found:
pub 4096R/D21739E9 2007-06-02 [expires: 2012-05-31]
Key fingerprint = 0EE5 BE97 9282 D80B 9F75 40F1 CCD2 ED94 D217 39E9
uid [ unknown] Daniel Kahn Gillmor <dkg@fifthhorseman.net>
uid [ unknown] Daniel Kahn Gillmor <dkg@openflows.com>
uid [ unknown] Daniel Kahn Gillmor <dkg@astro.columbia.edu>
uid [ unknown] Daniel Kahn Gillmor <dkg-debian.org@fifthhorseman.net>
uid [ unknown] [jpeg image of size 3515]
sub 2048R/4BFA08E4 2008-06-19 [expires: 2009-06-19]
sub 4096R/21484CFF 2007-06-02 [expires: 2012-05-31]
Are you sure you want to add the above key as a
certifier of users on this system? (y/N) y
gpg: key D21739E9: public key "Daniel Kahn Gillmor <dkg@fifthhorseman.net>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: next trustdb check due at 2009-03-30
gpg (GnuPG) 1.4.9; Copyright (C) 2008 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
pub 4096R/D21739E9 created: 2007-06-02 expires: 2012-05-31 usage: SC
trust: unknown validity: unknown
[ unknown] (1). Daniel Kahn Gillmor <dkg@fifthhorseman.net>
[ unknown] (2) Daniel Kahn Gillmor <dkg@openflows.com>
[ unknown] (3) Daniel Kahn Gillmor <dkg@astro.columbia.edu>
[ unknown] (4) Daniel Kahn Gillmor <dkg-debian.org@fifthhorseman.net>
[ unknown] (5) [jpeg image of size 3515]
pub 4096R/D21739E9 created: 2007-06-02 expires: 2012-05-31 usage: SC
trust: unknown validity: unknown
Primary key fingerprint: 0EE5 BE97 9282 D80B 9F75 40F1 CCD2 ED94 D217 39E9
Daniel Kahn Gillmor <dkg@fifthhorseman.net>
Daniel Kahn Gillmor <dkg@openflows.com>
Daniel Kahn Gillmor <dkg@astro.columbia.edu>
Daniel Kahn Gillmor <dkg-debian.org@fifthhorseman.net>
[jpeg image of size 3515]
This key is due to expire on 2012-05-31.
Please decide how far you trust this user to correctly verify other users' keys
(by looking at passports, checking fingerprints from different sources, etc.)
1 = I trust marginally
2 = I trust fully
Please enter the depth of this trust signature.
A depth greater than 1 allows the key you are signing to make
trust signatures on your behalf.
Please enter a domain to restrict this signature, or enter for none.
Are you sure that you want to sign this key with your
key "ssh://pip.fifthhorseman.net" (9B83C17D)
The signature will be marked as non-exportable.
gpg: can't create `/var/lib/monkeysphere/gnupg-host/pubring.gpg.tmp': Permission denied
gpg: failed to rebuild keyring cache: file open error
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 1 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 1f, 0u
gpg: next trustdb check due at 2009-03-30
Identity certifier added.
0 pip:~#
