SHARED MODULES BROKEN pdb: Increase version number to fix ABI
Alexander Bokovoy
ab at samba.org
Thu Dec 11 04:18:43 MST 2014
On Thu, Dec 11, 2014 at 10:46 AM, Andrew Bartlett <abartlet at samba.org> wrote:
> On Fri, 2014-12-05 at 22:43 +1300, Andrew Bartlett wrote:
>> On Thu, 2014-12-04 at 09:56 +0100, Andreas Schneider wrote:
>> > On Thursday 04 December 2014 11:08:06 Garming Sam wrote:
>> > > Hi Andreas,
>> >
>> > Hi Garming,
>> >
>> > >
>> > > Does the attached patch fix the issues you have?
>> > >
>> > > So far, I've mostly just tested what was mentioned below but I thought I
>> > > should get back to you.
>> >
>> > yes, this fixes the issue but I don't think this is the right way to do it!
>>
>> Can you explain why you don't think it is the right way?
>>
>> This approach allows the subsystem to remain named pdb (otherwise all
>> the init functions have to update, the on-disk directories have to
>> update etc), while the subsystem becomes part of the on-disk library
>> samba-passdb.
>>
>> Indeed, had we done this the first time, we wouldn't have needed to
>> update the other dependencies, which was an oversight.
>>
>> > Alexander spent quite some time fixing the pdb mess so we are able to build an
>> > external pdb module which is needed for FreeIPA. I think this will break it
>> > again!
>> >
>> >
>> > So this is a NAK on the patch until Alexander says otherwise :)
>>
>> Can you please test if this is or is not the case, rather than
>> hand-waving?
>
> Ping?
>
> Can you please clearly state what still fails after this patch is
> applied, as this objection is blocking the 4.2 release via #10355 and
> #10720.
NACK to Garming's patch. The problem with it is that it doesn't solve
the problem, it only makes it worse.
pdb initialization code relies on the static variable representing
list of registered modules (backends).
When you turn pdb into a grouping subsystem instead of linking
everything against a proper dynamic library, you get 'backends' static
variable duplicated multiple times in each compilation unit that
references it. Unfortunately, nothing will help you here to check that
there are duplicates of 'backends' variable because it is static. We
also have some subsystems that depend on 'pdb' subsystem and they then
get loaded into the same process.
As result, when static modules initialized, they operate on a
different backends variable than when dynamic modules are loaded
because they come through different code paths, linked from different
subsystems.
You can easily verify that there are multiple definitions of that
variable by querying a symbol from source3/passdb/pdb_interface.c
(where static variable is defined), like smb_register_passdb.
Current state in master if I compile most of passdb modules shared as
Andreas mentioned in his email:
$ find bin -name '*.*o' |while read ; do usage=$(nm -a $REPLY |grep
smb_register_passdb) ; test $? -eq 0 && printf "%46s %s\n" "$REPLY"
"$usage"; done
bin/default/examples/pdb/libpdb-test.so 00000000000292f5 T
smb_register_passdb
bin/default/examples/pdb/test_1.o U
smb_register_passdb
bin/default/source3/pam_smbpass/libpamsmbpass.so 000000000002fce7 T
smb_register_passdb
bin/default/source3/passdb/libpdb-tdbsam.so 000000000002d11a T
smb_register_passdb
bin/default/source3/passdb/pdb_tdb_1.o U
smb_register_passdb
bin/default/source3/passdb/pdb_samba_dsdb_9.o U
smb_register_passdb
bin/default/source3/passdb/pdb_nds_3.o U
smb_register_passdb
bin/default/source3/passdb/pdb_wbc_sam_7.o U
smb_register_passdb
bin/default/source3/passdb/pdb_ldap_3.o U
smb_register_passdb
bin/default/source3/passdb/pypassdb.so 0000000000034de0 T
smb_register_passdb
bin/default/source3/passdb/libpdb-wbc-sam.so 0000000000029afc T
smb_register_passdb
bin/default/source3/passdb/libpdb-smbpasswd.so 000000000002ea8f T
smb_register_passdb
bin/default/source3/passdb/libpdb-ldapsam.so 00000000000454f8 T
smb_register_passdb
bin/default/source3/passdb/pdb_interface_28.o 000000000000001f T
smb_register_passdb
bin/default/source3/passdb/pdb_smbpasswd_5.o U
smb_register_passdb
bin/default/source3/passdb/pdb_ipa_3.o U
smb_register_passdb
bin/default/source3/libsamba-passdb.so 0000000000028c8c T
smb_register_passdb
bin/modules/samba-passdb/pdb_wbc_sam.so 0000000000029afc T
smb_register_passdb
bin/modules/samba-passdb/pdb_smbpasswd.so 000000000002ea8f T
smb_register_passdb
bin/modules/samba-passdb/pdb_ldapsam.so 00000000000454f8 T
smb_register_passdb
bin/modules/samba-passdb/pdb_tdbsam.so 000000000002d11a T
smb_register_passdb
bin/modules/samba-passdb/pdb_test.so 00000000000292f5 T
smb_register_passdb
bin/modules/pdb-modules/pdb_wbc_sam.so 0000000000029afc T
smb_register_passdb
bin/modules/pdb-modules/pdb_smbpasswd.so 000000000002ea8f T
smb_register_passdb
bin/modules/pdb-modules/pdb_ldapsam.so 00000000000454f8 T
smb_register_passdb
bin/modules/pdb-modules/pdb_tdbsam.so 000000000002d11a T
smb_register_passdb
bin/modules/pdb/test.so 00000000000292f5 T
smb_register_passdb
bin/modules/pdb/ldapsam.so 00000000000454f8 T
smb_register_passdb
bin/modules/pdb/tdbsam.so 000000000002d11a T
smb_register_passdb
bin/modules/pdb/smbpasswd.so 000000000002ea8f T
smb_register_passdb
bin/modules/pdb/wbc_sam.so 0000000000029afc T
smb_register_passdb
bin/python/samba/samba3/passdb.so 0000000000034de0 T
smb_register_passdb
bin/shared/pam_smbpass.so 000000000002fce7 T
smb_register_passdb
As you can see, there are 24 shared modules where smb_register_passdb
function is defined which means there are 24 places with 'backends'
static linked list. This is calling for a disaster.
With the attached patch I get:
$ find bin -name '*.*o' |while read ; do usage=$(nm -a $REPLY |grep
smb_register_passdb) ; test $? -eq 0 && printf "%46s %s\n" "$REPLY"
"$usage"; done
bin/default/examples/pdb/libpdb-test.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/default/examples/pdb/test_1.o U
smb_register_passdb
bin/default/source3/passdb/libpdb-tdbsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/default/source3/passdb/pdb_tdb_1.o U
smb_register_passdb
bin/default/source3/passdb/pdb_samba_dsdb_9.o U
smb_register_passdb
bin/default/source3/passdb/pdb_nds_3.o U
smb_register_passdb
bin/default/source3/passdb/pdb_wbc_sam_7.o U
smb_register_passdb
bin/default/source3/passdb/pdb_ldap_3.o U
smb_register_passdb
bin/default/source3/passdb/libpdb-wbc-sam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/default/source3/passdb/libpdb-smbpasswd.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/default/source3/passdb/libpdb-ldapsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/default/source3/passdb/pdb_interface_28.o 000000000000001f T
smb_register_passdb
bin/default/source3/passdb/pdb_smbpasswd_5.o U
smb_register_passdb
bin/default/source3/passdb/pdb_ipa_3.o U
smb_register_passdb
bin/default/source3/libsamba-passdb.so 0000000000028c8c T
smb_register_passdb
bin/modules/samba-passdb/pdb_wbc_sam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/samba-passdb/pdb_smbpasswd.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/samba-passdb/pdb_ldapsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/samba-passdb/pdb_tdbsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/samba-passdb/pdb_test.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb-modules/pdb_wbc_sam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb-modules/pdb_smbpasswd.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb-modules/pdb_ldapsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb-modules/pdb_tdbsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb/test.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb/ldapsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb/tdbsam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb/smbpasswd.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
bin/modules/pdb/wbc_sam.so U
smb_register_passdb@@SAMBA_PASSDB_0.2.0
As you can see, there is one place where the unit with
smb_register_passdb is defined (pdb_interface_28.o) and it is linked
into libsamba-passdb.so which is then used by all other code.
--
/ Alexander Bokovoy
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-passdb-ensure-every-user-of-passdb-code-uses-samba-p.patch
Type: text/x-patch
Size: 7233 bytes
Desc: not available
URL: <http://lists.samba.org/pipermail/samba-technical/attachments/20141211/419162de/attachment.bin>
More information about the samba-technical
mailing list