Re: Minor issues in .pgpass

On 2020/01/22 9:06, David Fetter wrote:
> On Tue, Jan 21, 2020 at 03:27:50PM +0900, Fujii Masao wrote:
>> Hi,
>>
>> When I was researching the maximum length of password in PostgreSQL
>> to answer the question from my customer, I found that there are two
>> minor issues in .pgpass file.
>>
>> (1) If the length of a line in .pgpass file is larger than 319B,
>>         libpq silently treats each 319B in the line as a separate
>>         setting line.
> 
> This seems like a potentially serious bug. For example, a truncated
> password could get retried enough times to raise intruder alarms, and
> it wouldn't be easy to track down.
> 
>> (2) The document explains that a line beginning with # is treated
>>         as a comment in .pgpass. But as far as I read the code,
>>         there is no code doing such special handling.
> 
> This is a flat-out bug, as it violates a promise the documentation has
> made.
> 
>>         Also if the length of that "comment" line is larger than 319B,
>>         the latter part of the line can be treated as valid setting.
> 
>> You may think that these unexpected behaviors are not so harmful
>> in practice because "usually" the length of password setting line is
>> less than 319B and the hostname beginning with # is less likely to be
>> used. But the problem exists. And there are people who want to use
>> large password or to write a long comment (e.g., with multibyte
>> characters like Japanese) in .pgass, so these may be more harmful
>> in the near future.
>>
>> For (1), I think that we should make libpq warn if the length of a line
>> is larger than 319B, and throw away the remaining part beginning from
>> 320B position. Whether to enlarge the length of a line should be
>> a separate discussion, I think.
> 
> Agreed.
> 
>> For (2), libpq should treat any lines beginning with # as comments.

Patch attached. This patch does the above (1) and (2).

> Would it make sense for lines starting with whitespace and then # to
> be treated as comments, too, e.g.:

Could you tell me why you want to treat such a line as comment?
Basically I don't want to change the existing rules for parsing
.pgpass file more thane necessary.

Regards,

-- 
Fujii Masao
NTT DATA CORPORATION
Advanced Platform Technology Group
Research and Development Headquarters