From: David Gibson <david@gibson.dropbear.id.au>
To: passt-dev@passt.top
Subject: Re: [PATCH 07/28] Clean up parsing in conf_runas()
Date: Thu, 29 Sep 2022 11:44:21 +1000 [thread overview]
Message-ID: <YzT4dYUdDb2ahSCU@yekko> (raw)
In-Reply-To: <20220928225755.6bfb59f9@elisabeth>
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On Wed, Sep 28, 2022 at 10:57:55PM +0200, Stefano Brivio wrote:
> On Wed, 28 Sep 2022 14:33:18 +1000
> David Gibson <david(a)gibson.dropbear.id.au> wrote:
>
> > conf_runas() handles several of the different possible cases for the
> > --runas argument in a slightly odd order. Although it can parse both
> > numeric UIDs/GIDs and user/group names, it can't parse a numeric UID
> > combined with a group name or vice versa. That's not obviously useful, but
> > it's slightly surprising gap to have.
>
> Ah, actually, I had noticed that: I usually type my UID as number, but
> I can't remember GIDs... then I had half a mind of "fixing" that, and
> never got to it.
>
> > [...]
> >
> > +++ b/conf.c
> > @@ -859,46 +859,50 @@ dns6:
> > *
> > * Return: 0 on success, negative error code on failure
> > */
> > -static int conf_runas(const char *opt, unsigned int *uid, unsigned int *gid)
> > +static int conf_runas(char *opt, unsigned int *uid, unsigned int *gid)
>
> While I like your approach better than the existing one, I see one
> detail that, albeit minor, might drive somebody mad: if the UID is
> valid, but the GID isn't, we go back to conf_ugid():
>
> if (ret)
> err("Invalid --runas option: %s", runas);
>
> and print the UID part, only, because we cut before the separator.
Urgh, right. This is why having worked a bit with Rust and Go, I'm
really coming to hate C-style strings: even really rudimentary parsing
usually requires either allocation & copies or modifying logically
read-only inputs.
> Perhaps we could simply put the separator back before returning
> -EINVAL (instead of copying the buffer) -- we just have zero or one
> occurrences of ':'.
That would work, although making sure we do that on every exit path
looks messier than I'd like. I went with a different approach of
removing that message from the caller, and instead printing more
specific messages for each of the cases within conf_runas(). A little
more involved, but I think gives a marginally better UX overall.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2022-09-29 1:44 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-28 4:33 [PATCH 00/28] Fixes for static checkers David Gibson
2022-09-28 4:33 ` [PATCH 01/28] Clean up parsing of port ranges David Gibson
2022-09-28 20:57 ` Stefano Brivio
2022-09-29 1:04 ` David Gibson
2022-09-28 4:33 ` [PATCH 02/28] clang-tidy: Suppress warning about unchecked error in logfn macro David Gibson
2022-09-28 4:33 ` [PATCH 03/28] clang-tidy: Fix spurious null pointer warning in pasta_start_ns() David Gibson
2022-09-28 4:33 ` [PATCH 04/28] clang-tidy: Remove duplicate #include from icmp.c David Gibson
2022-09-28 4:33 ` [PATCH 05/28] Catch failures when installing signal handlers David Gibson
2022-09-28 4:33 ` [PATCH 06/28] Pack DHCPv6 "on wire" structures David Gibson
2022-09-28 4:33 ` [PATCH 07/28] Clean up parsing in conf_runas() David Gibson
2022-09-28 20:57 ` Stefano Brivio
2022-09-29 1:44 ` David Gibson [this message]
2022-09-28 4:33 ` [PATCH 08/28] cppcheck: Reduce scope of some variables David Gibson
2022-09-28 4:33 ` [PATCH 09/28] Don't shadow 'i' in conf_ports() David Gibson
2022-09-28 4:33 ` [PATCH 10/28] Don't shadow global function names David Gibson
2022-09-28 4:33 ` [PATCH 11/28] Stricter checking for nsholder.c David Gibson
2022-09-28 4:33 ` [PATCH 12/28] cppcheck: Work around false positive NULL pointer dereference error David Gibson
2022-09-28 4:33 ` [PATCH 13/28] cppcheck: Use inline suppression for ffsl() David Gibson
2022-09-28 4:33 ` [PATCH 14/28] cppcheck: Use inline suppressions for qrap.c David Gibson
2022-09-28 4:33 ` [PATCH 15/28] cppcheck: Use inline suppression for strtok() in conf.c David Gibson
2022-09-28 4:33 ` [PATCH 16/28] Avoid ugly 'end' members in netlink structures David Gibson
2022-09-28 4:33 ` [PATCH 17/28] cppcheck: Broaden suppression for unused struct members David Gibson
2022-09-28 4:33 ` [PATCH 18/28] cppcheck: Remove localtime suppression for pcap.c David Gibson
2022-09-28 4:33 ` [PATCH 19/28] qrap: Handle case of PATH environment variable being unset David Gibson
2022-09-28 4:33 ` [PATCH 20/28] cppcheck: Suppress same-value-in-ternary branches warning David Gibson
2022-09-28 20:58 ` Stefano Brivio
2022-09-29 1:00 ` David Gibson
2022-09-28 4:33 ` [PATCH 21/28] cppcheck: Suppress NULL pointer warning in tcp_sock_consume() David Gibson
2022-09-28 20:58 ` Stefano Brivio
2022-09-29 1:07 ` David Gibson
2022-09-28 4:33 ` [PATCH 22/28] Regenerate seccomp.h if seccomp.sh changes David Gibson
2022-09-28 4:33 ` [PATCH 23/28] cppcheck: Avoid errors due to zeroes in bitwise ORs David Gibson
2022-09-28 4:33 ` [PATCH 24/28] cppcheck: Remove unused knownConditionTrueFalse suppression David Gibson
2022-09-28 20:58 ` Stefano Brivio
2022-09-29 1:24 ` David Gibson
2022-09-28 4:33 ` [PATCH 25/28] cppcheck: Remove unused objectIndex suppressions David Gibson
2022-09-28 20:58 ` Stefano Brivio
2022-09-29 1:12 ` David Gibson
2022-09-28 4:33 ` [PATCH 26/28] cppcheck: Remove unused va_list_usedBeforeStarted suppression David Gibson
2022-09-28 4:33 ` [PATCH 27/28] Mark unused functions for cppcheck David Gibson
2022-09-28 4:33 ` [PATCH 28/28] cppcheck: Remove unused unmatchedSuppression suppressions David Gibson
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