Description

erlend-aasland

opened on Sep 19, 2021

Issue body actions

BPO	45243
Nosy	@tiran, @berkerpeksag, @serhiy-storchaka, @zooba, @pablogsal, @erlend-aasland
PRs	bpo-45243: Add support for setting/getting sqlite3 connection limits #28463 bpo-45243: Expose SQLite connection limits as sqlite3.Connection attributes #28790 bpo-45243: Use connection limits to simplify sqlite3 tests #29356

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/erlend-aasland'
closed_at = <Date 2021-11-13.21:17:03.972>
created_at = <Date 2021-09-19.22:35:54.394>
labels = ['extension-modules', 'type-feature']
title = '[sqlite3] add support for changing connection limits'
updated_at = <Date 2021-11-13.21:17:03.972>
user = 'https://github.com/erlend-aasland'

bugs.python.org fields:

activity = <Date 2021-11-13.21:17:03.972>
actor = 'erlendaasland'
assignee = 'erlendaasland'
closed = True
closed_date = <Date 2021-11-13.21:17:03.972>
closer = 'erlendaasland'
components = ['Extension Modules']
creation = <Date 2021-09-19.22:35:54.394>
creator = 'erlendaasland'
dependencies = []
files = []
hgrepos = []
issue_num = 45243
keywords = ['patch']
message_count = 5.0
messages = ['402176', '402186', '405474', '405566', '405811']
nosy_count = 6.0
nosy_names = ['christian.heimes', 'berker.peksag', 'serhiy.storchaka', 'steve.dower', 'pablogsal', 'erlendaasland']
pr_nums = ['28463', '28790', '29356']
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45243'
versions = []

Activity

1. erlend-aasland commented on Sep 19, 2021

   

   erlend-aasland

   on Sep 19, 2021

   ContributorAuthor

   More actions

   I propose to add wrappers for the SQLite sqlite3_limit() C API. Using this API, it is possible to query and set limits on a connection basis. This will make it easier (and faster) to test various corner cases in the test suite without relying on test.support.bigmemtest.

   Quoting from the SQLite sqlite3_limit() docs:

   Run-time limits are intended for use in applications that manage both their
   own internal database and also databases that are controlled by untrusted
   external sources. An example application might be a web browser that has its
   own databases for storing history and separate databases controlled by
   JavaScript applications downloaded off the Internet. The internal databases
   can be given the large, default limits. Databases managed by external
   sources can be given much smaller limits designed to prevent a denial of
   service attack.

   See also:

   • https://sqlite.org/c3ref/limit.html
   • https://sqlite.org/c3ref/c_limit_attached.html
   • https://sqlite.org/limits.html

   Limit categories (C&P from SQLite docs)
   ---------------------------------------

   SQLITE_LIMIT_LENGTH
   The maximum size of any string or BLOB or table row, in bytes.

   SQLITE_LIMIT_SQL_LENGTH
   The maximum length of an SQL statement, in bytes.

   SQLITE_LIMIT_COLUMN
   The maximum number of columns in a table definition or in the result set of a SELECT or the maximum number of columns in an index or in an ORDER BY or GROUP BY clause.

   SQLITE_LIMIT_EXPR_DEPTH
   The maximum depth of the parse tree on any expression.

   SQLITE_LIMIT_COMPOUND_SELECT
   The maximum number of terms in a compound SELECT statement.

   SQLITE_LIMIT_VDBE_OP
   The maximum number of instructions in a virtual machine program used to implement an SQL statement. If sqlite3_prepare_v2() or the equivalent tries to allocate space for more than this many opcodes in a single prepared statement, an SQLITE_NOMEM error is returned.

   SQLITE_LIMIT_FUNCTION_ARG
   The maximum number of arguments on a function.

   SQLITE_LIMIT_ATTACHED
   The maximum number of attached databases.

   SQLITE_LIMIT_LIKE_PATTERN_LENGTH
   The maximum length of the pattern argument to the LIKE or GLOB operators.

   SQLITE_LIMIT_VARIABLE_NUMBER
   The maximum index number of any parameter in an SQL statement.

   SQLITE_LIMIT_TRIGGER_DEPTH
   The maximum depth of recursion for triggers.

   SQLITE_LIMIT_WORKER_THREADS
   The maximum number of auxiliary worker threads that a single prepared statement may start.
2. erlend-aasland

   self-assigned this

   on Sep 19, 2021
3. erlend-aasland

   added

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   type-featureA feature request or enhancementA feature request or enhancement

   on Sep 19, 2021
4. erlend-aasland

   self-assigned this

   on Sep 19, 2021
5. erlend-aasland

   added

   extension-modulesC modules in the Modules dirC modules in the Modules dir

   type-featureA feature request or enhancementA feature request or enhancement

   on Sep 19, 2021
6. erlend-aasland commented on Sep 19, 2021

   

   erlend-aasland

   on Sep 19, 2021

   ContributorAuthor

   More actions

   Christian, how about adding an audit event for something like sqlite3.Connection.setlimit()? My initial thought is: yes.
7. pablogsal commented on Nov 1, 2021

   

   pablogsal

   on Nov 1, 2021

   Member

   More actions

   New changeset b6b38a8 by Erlend Egeberg Aasland in branch 'main':
   bpo-45243: Add support for setting/getting sqlite3 connection limits (GH-28463)
   b6b38a8
8. erlend-aasland commented on Nov 2, 2021

   

   erlend-aasland

   on Nov 2, 2021

   ContributorAuthor

   More actions

   Steve, do you think it is worth it adding an audit hook for setting connection limits?

   Most of the limits are harmless, but limits that control recursion are more interesting.

   SQLITE_LIMIT_EXPR_DEPTH:

   Maximum Depth Of An Expression Tree
   
   SQLite parses expressions into a tree for processing. During code
   generation, SQLite walks this tree recursively. The depth of expression
   trees is therefore limited in order to avoid using too much stack space.
   [...] If the value is 0, then no limit is enforced.
   

   SQLITE_LIMIT_TRIGGER_DEPTH:

   Maximum Depth Of Trigger Recursion
   
   SQLite limits the depth of recursion of triggers in order to prevent a
   statement involving recursive triggers from using an unbounded amount of
   memory.
   

   Note also, how the SQLite docs talk about SQLITE_LIMIT_LENGTH:

   Maximum length of a string or BLOB
   
   [...] In security-sensitive applications it is best not to try to increase
   the maximum string and blob length. In fact, you might do well to lower
   the maximum string and blob length to something more in the range of a few
   million if that is possible.
   
9. serhiy-storchaka commented on Nov 5, 2021

   

   serhiy-storchaka

   on Nov 5, 2021

   Member

   More actions

   New changeset 3d42cd9 by Erlend Egeberg Aasland in branch 'main':
   bpo-45243: Use connection limits to simplify sqlite3 tests (GH-29356)
   3d42cd9
10. erlend-aasland

    closed this as completedon Nov 13, 2021
11. erlend-aasland

    closed this as completedon Nov 13, 2021
12. ezio-melotti

    transferred this issue fromon Apr 10, 2022
13. erlend-aasland

    added

    topic-sqlite3

    on May 16, 2022

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