postgres

Author SHA1 Message Date

Author	SHA1	Message	Date
Tom Lane	7eeb1d9861	Make contrib modules' installation scripts more secure. Hostile objects located within the installation-time search_path could capture references in an extension's installation or upgrade script. If the extension is being installed with superuser privileges, this opens the door to privilege escalation. While such hazards have existed all along, their urgency increases with the v13 "trusted extensions" feature, because that lets a non-superuser control the installation path for a superuser-privileged script. Therefore, make a number of changes to make such situations more secure: * Tweak the construction of the installation-time search_path to ensure that references to objects in pg_catalog can't be subverted; and explicitly add pg_temp to the end of the path to prevent attacks using temporary objects. * Disable check_function_bodies within installation/upgrade scripts, so that any security gaps in SQL-language or PL-language function bodies cannot create a risk of unwanted installation-time code execution. * Adjust lookup of type input/receive functions and join estimator functions to complain if there are multiple candidate functions. This prevents capture of references to functions whose signature is not the first one checked; and it's arguably more user-friendly anyway. * Modify various contrib upgrade scripts to ensure that catalog modification queries are executed with secure search paths. (These are in-place modifications with no extension version changes, since it is the update process itself that is at issue, not the end result.) Extensions that depend on other extensions cannot be made fully secure by these methods alone; therefore, revert the "trusted" marking that commit `eb67623c9` applied to earthdistance and hstore_plperl, pending some better solution to that set of issues. Also add documentation around these issues, to help extension authors write secure installation scripts. Patch by me, following an observation by Andres Freund; thanks to Noah Misch for review. Security: CVE-2020-14350	6 years ago
Tom Lane	de1d042f59	Support index-only scans in contrib/cube and contrib/seg GiST indexes. To do this, we only have to remove the compress and decompress support functions, which have never done anything more than detoasting. In the wake of commit `d3a4f89d8`, this results in automatically enabling index-only scans, since the core code will now know that the stored representation is the same as the original data (up to detoasting). The only exciting part of this is that ALTER OPERATOR FAMILY lacks a way to drop a support function that was declared as being part of an opclass rather than being loose in the family. For the moment, we'll hack our way to a solution with a manual update of the pg_depend entry type, which is what distinguishes the two cases. Perhaps someday it'll be worth providing a cleaner way to do that, but for now it seems like a very niche problem. Note that the underlying C functions remain, to support use of the shared libraries with older versions of the modules' SQL declarations. Someday we may be able to remove them, but not soon. Andrey Borodin, reviewed by me Discussion: https://postgr.es/m/D0F53A05-4F4A-4DEC-8339-3C069FA0EE11@yandex-team.ru	8 years ago

Tom Lane

Make contrib modules' installation scripts more secure.

Hostile objects located within the installation-time search_path could
capture references in an extension's installation or upgrade script.
If the extension is being installed with superuser privileges, this
opens the door to privilege escalation.  While such hazards have existed
all along, their urgency increases with the v13 "trusted extensions"
feature, because that lets a non-superuser control the installation path
for a superuser-privileged script.  Therefore, make a number of changes
to make such situations more secure:

* Tweak the construction of the installation-time search_path to ensure
that references to objects in pg_catalog can't be subverted; and
explicitly add pg_temp to the end of the path to prevent attacks using
temporary objects.

* Disable check_function_bodies within installation/upgrade scripts,
so that any security gaps in SQL-language or PL-language function bodies
cannot create a risk of unwanted installation-time code execution.

* Adjust lookup of type input/receive functions and join estimator
functions to complain if there are multiple candidate functions.  This
prevents capture of references to functions whose signature is not the
first one checked; and it's arguably more user-friendly anyway.

* Modify various contrib upgrade scripts to ensure that catalog
modification queries are executed with secure search paths.  (These
are in-place modifications with no extension version changes, since
it is the update process itself that is at issue, not the end result.)

Extensions that depend on other extensions cannot be made fully secure
by these methods alone; therefore, revert the "trusted" marking that
commit eb67623c9 applied to earthdistance and hstore_plperl, pending
some better solution to that set of issues.

Also add documentation around these issues, to help extension authors
write secure installation scripts.

Patch by me, following an observation by Andres Freund; thanks
to Noah Misch for review.

Security: CVE-2020-14350

6 years ago

Tom Lane

de1d042f59

Support index-only scans in contrib/cube and contrib/seg GiST indexes.

To do this, we only have to remove the compress and decompress support
functions, which have never done anything more than detoasting.
In the wake of commit d3a4f89d8, this results in automatically enabling
index-only scans, since the core code will now know that the stored
representation is the same as the original data (up to detoasting).

The only exciting part of this is that ALTER OPERATOR FAMILY lacks
a way to drop a support function that was declared as being part of
an opclass rather than being loose in the family.  For the moment,
we'll hack our way to a solution with a manual update of the pg_depend
entry type, which is what distinguishes the two cases.  Perhaps
someday it'll be worth providing a cleaner way to do that, but for
now it seems like a very niche problem.

Note that the underlying C functions remain, to support use of the shared
libraries with older versions of the modules' SQL declarations.  Someday
we may be able to remove them, but not soon.

Andrey Borodin, reviewed by me

Discussion: https://postgr.es/m/D0F53A05-4F4A-4DEC-8339-3C069FA0EE11@yandex-team.ru

8 years ago

2 Commits (e35add48ccc2e5aa94de360f1a43c6c150bda54a)