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2021-06-07Fix incautious handling of possibly-miscoded strings in client code.Tom Lane
An incorrectly-encoded multibyte character near the end of a string could cause various processing loops to run past the string's terminating NUL, with results ranging from no detectable issue to a program crash, depending on what happens to be in the following memory. This isn't an issue in the server, because we take care to verify the encoding of strings before doing any interesting processing on them. However, that lack of care leaked into client-side code which shouldn't assume that anyone has validated the encoding of its input. Although this is certainly a bug worth fixing, the PG security team elected not to regard it as a security issue, primarily because any untrusted text should be sanitized by PQescapeLiteral or the like before being incorporated into a SQL or psql command. (If an app fails to do so, the same technique can be used to cause SQL injection, with probably much more dire consequences than a mere client-program crash.) Those functions were already made proof against this class of problem, cf CVE-2006-2313. To fix, invent PQmblenBounded() which is like PQmblen() except it won't return more than the number of bytes remaining in the string. In HEAD we can make this a new libpq function, as PQmblen() is. It seems imprudent to change libpq's API in stable branches though, so in the back branches define PQmblenBounded as a macro in the files that need it. (Note that just changing PQmblen's behavior would not be a good idea; notably, it would completely break the escaping functions' defense against this exact problem. So we just want a version for those callers that don't have any better way of handling this issue.) Per private report from houjingyi. Back-patch to all supported branches.
2018-11-26Fix translation of special characters in psql's LaTeX output modes.Tom Lane
latex_escaped_print() mistranslated \ and failed to provide any translation for # ^ and ~, all of which would typically lead to LaTeX document syntax errors. In addition it didn't translate < > and |, which would typically render as unexpected characters. To some extent this represents shortcomings in ancient versions of LaTeX, which if memory serves had no easy way to render these control characters as ASCII text. But that's been fixed for, um, decades. In any case there is no value in emitting guaranteed-to-fail output for these characters. Noted while fooling with test cases added by commit 9a98984f4. Back-patch the code change to all supported versions.
2018-08-23Fix lexing of standard multi-character operators in edge cases.Andrew Gierth
Commits c6b3c939b (which fixed the precedence of >=, <=, <> operators) and 865f14a2d (which added support for the standard => notation for named arguments) created a class of lexer tokens which look like multi-character operators but which have their own token IDs distinct from Op. However, longest-match rules meant that following any of these tokens with another operator character, as in (1<>-1), would cause them to be incorrectly returned as Op. The error here isn't immediately obvious, because the parser would usually still find the correct operator via the Op token, but there were more subtle problems: 1. If immediately followed by a comment or +-, >= <= <> would be given the old precedence of Op rather than the correct new precedence; 2. If followed by a comment, != would be returned as Op rather than as NOT_EQUAL, causing it not to be found at all; 3. If followed by a comment or +-, the => token for named arguments would be lexed as Op, causing the argument to be mis-parsed as a simple expression, usually causing an error. Fix by explicitly checking for the operators in the {operator} code block in addition to all the existing special cases there. Backpatch to 9.5 where the problem was introduced. Analysis and patch by me; review by Tom Lane. Discussion: https://postgr.es/m/87va851ppl.fsf@news-spur.riddles.org.uk
2018-08-23Reduce an unnecessary O(N^3) loop in lexer.Andrew Gierth
The lexer's handling of operators contained an O(N^3) hazard when dealing with long strings of + or - characters; it seems hard to prevent this case from being O(N^2), but the additional N multiplier was not needed. Backpatch all the way since this has been there since 7.x, and it presents at least a mild hazard in that trying to do Bind, PREPARE or EXPLAIN on a hostile query could take excessive time (without honouring cancels or timeouts) even if the query was never executed.
2018-02-26Empty search_path in Autovacuum and non-psql/pgbench clients.Noah Misch
This makes the client programs behave as documented regardless of the connect-time search_path and regardless of user-created objects. Today, a malicious user with CREATE permission on a search_path schema can take control of certain of these clients' queries and invoke arbitrary SQL functions under the client identity, often a superuser. This is exploitable in the default configuration, where all users have CREATE privilege on schema "public". This changes behavior of user-defined code stored in the database, like pg_index.indexprs and pg_extension_config_dump(). If they reach code bearing unqualified names, "does not exist" or "no schema has been selected to create in" errors might appear. Users may fix such errors by schema-qualifying affected names. After upgrading, consider watching server logs for these errors. The --table arguments of src/bin/scripts clients have been lax; for example, "vacuumdb -Zt pg_am\;CHECKPOINT" performed a checkpoint. That now fails, but for now, "vacuumdb -Zt 'pg_am(amname);CHECKPOINT'" still performs a checkpoint. Back-patch to 9.3 (all supported versions). Reviewed by Tom Lane, though this fix strategy was not his first choice. Reported by Arseniy Sharoglazov. Security: CVE-2018-1058
2016-12-07Restore psql's SIGPIPE setting if popen() fails.Tom Lane
Ancient oversight in PageOutput(): if popen() fails, we'd better reset the SIGPIPE handler before returning stdout, because ClosePager() won't. Noticed while fixing the empty-PAGER issue.
2016-12-07Handle empty or all-blank PAGER setting more sanely in psql.Tom Lane
If the PAGER environment variable is set but contains an empty string, psql would pass it to "sh" which would silently exit, causing whatever query output we were printing to vanish entirely. This is quite mystifying; it took a long time for us to figure out that this was the cause of Joseph Brenner's trouble report. Rather than allowing that to happen, we should treat this as another way to specify "no pager". (We could alternatively treat it as selecting the default pager, but it seems more likely that the former is what the user meant to achieve by setting PAGER this way.) Nonempty, but all-white-space, PAGER values have the same behavior, and it's pretty easy to test for that, so let's handle that case the same way. Most other cases of faulty PAGER values will result in the shell printing some kind of complaint to stderr, which should be enough to diagnose the problem, so we don't need to work harder than this. (Note that there's been an intentional decision not to be very chatty about apparent failure returns from the pager process, since that may happen if, eg, the user quits the pager with control-C or some such. I'd just as soon not start splitting hairs about which exit codes might merit making our own report.) libpq's old PQprint() function was already on board with ignoring empty PAGER values, but for consistency, make it ignore all-white-space values as well. It's been like this a long time, so back-patch to all supported branches. Discussion: https://postgr.es/m/CAFfgvXWLOE2novHzYjmQK8-J6TmHz42G8f3X0SORM44+stUGmw@mail.gmail.com
2016-08-16Fix assorted places in psql to print version numbers >= 10 in new style.Tom Lane
This is somewhat cosmetic, since as long as you know what you are looking at, "10.0" is a serviceable substitute for "10". But there is a potential for confusion between version numbers with minor numbers and those without --- we don't want people asking "why is psql saying 10.0 when my server is 10.2". Therefore, back-patch as far as practical, which turns out to be 9.3. I could have redone the patch to use fprintf(stderr) in place of psql_error(), but it seems more work than is warranted for branches that will be EOL or nearly so by the time v10 comes out. Although only psql seems to contain any code that needs this, I chose to put the support function into fe_utils, since it seems likely we'll need it in other client programs in future. (In 9.3-9.5, use dumputils.c, the predecessor of fe_utils/string_utils.c.) In HEAD, also fix the backend code that whines about loadable-library version mismatch. I don't see much need to back-patch that.
2016-08-08Obstruct shell, SQL, and conninfo injection via database and role names.Noah Misch
Due to simplistic quoting and confusion of database names with conninfo strings, roles with the CREATEDB or CREATEROLE option could escalate to superuser privileges when a superuser next ran certain maintenance commands. The new coding rule for PQconnectdbParams() calls, documented at conninfo_array_parse(), is to pass expand_dbname=true and wrap literal database names in a trivial connection string. Escape zero-length values in appendConnStrVal(). Back-patch to 9.1 (all supported versions). Nathan Bossart, Michael Paquier, and Noah Misch. Reviewed by Peter Eisentraut. Reported by Nathan Bossart. Security: CVE-2016-5424
2016-08-08Promote pg_dumpall shell/connstr quoting functions to src/fe_utils.Noah Misch
Rename these newly-extern functions with terms more typical of their new neighbors. No functional changes; a subsequent commit will use them in more places. Back-patch to 9.1 (all supported versions). Back branches lack src/fe_utils, so instead rename the functions in place; the subsequent commit will copy them into the other programs using them. Security: CVE-2016-5424
2016-05-15Fix comment.Tom Lane
Reference to getThreadLocalPQExpBuffer here seems inappropriate, since we aren't necessarily using that instantiation of getLocalPQExpBuffer.
2016-05-06Move and rename fmtReloptionsArray().Dean Rasheed
Move fmtReloptionsArray() from pg_dump.c to string_utils.c so that it is available to other frontend code. In particular psql's \ev and \sv commands need it to handle view reloptions. Also rename the function to appendReloptionsArray(), which is a more accurate description of what it does. Author: Dean Rasheed Reviewed-by: Peter Eisentraut Discussion: http://www.postgresql.org/message-id/CAEZATCWZjCgKRyM-agE0p8ax15j9uyQoF=qew7D2xB6cF76T8A@mail.gmail.com
2016-04-08Support \crosstabview in psqlAlvaro Herrera
\crosstabview is a completely different way to display results from a query: instead of a vertical display of rows, the data values are placed in a grid where the column and row headers come from the data itself, similar to a spreadsheet. The sort order of the horizontal header can be specified by using another column in the query, and the vertical header determines its ordering from the order in which they appear in the query. This only allows displaying a single value in each cell. If more than one value correspond to the same cell, an error is thrown. Merging of values can be done in the query itself, if necessary. This may be revisited in the future. Author: Daniel Verité Reviewed-by: Pavel Stehule, Dean Rasheed
2016-03-24Move psql's psqlscan.l into src/fe_utils.Tom Lane
This completes (at least for now) the project of getting rid of ad-hoc linkages among the src/bin/ subdirectories. Everything they share is now in src/fe_utils/ and is included from a static library at link time. A side benefit is that we can restore the FLEX_NO_BACKUP check for psqlscanslash.l. We might need to think of another way to do that check if we ever need to build two lexers with that property in the same source directory, but there's no foreseeable reason to need that.
2016-03-24Move psql's print.c and mbprint.c into src/fe_utils.Tom Lane
Just turning the crank ...
2016-03-24Create src/fe_utils/, and move stuff into there from pg_dump's dumputils.Tom Lane
Per discussion, we want to create a static library and put the stuff into it that until now has been shared across src/bin/ directories by ad-hoc methods like symlinking a source file. This commit creates the library and populates it with a couple of files that contain the widely-useful portions of pg_dump's dumputils.c file. dumputils.c survives, because it has some stuff that didn't seem appropriate for fe_utils, but it's significantly smaller and is no longer referenced from any other directory. Follow-on patches will move more stuff into fe_utils. The Mkvcbuild.pm hacking here is just a best guess; we'll see how the buildfarm likes it.