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From: Carlo Arenas <carenas@gmail.com>
To: phillip.wood@dunelm.org.uk
Cc: "Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
	git@vger.kernel.org, gitster@pobox.com, bagasdotme@gmail.com,
	"Guy Maurel" <guy.j@maurel.de>,
	"SZEDER Gábor" <szeder.dev@gmail.com>,
	"Randall Becker" <rsbecker@nexbridge.com>
Subject: Re: [PATCH v3 2/3] git-compat-util: avoid failing dir ownership checks if running privileged
Date: Fri, 6 May 2022 12:15:06 -0700	[thread overview]
Message-ID: <CAPUEspiMsvNhQF-RjW5eu3Xco9gU7TFt4w9dOOcF1PGM4Z+ceQ@mail.gmail.com> (raw)
In-Reply-To: <c9fc0fc6-c688-022d-9476-aaa87c66d295@gmail.com>

On Thu, May 5, 2022 at 7:32 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
> On 05/05/2022 15:01, Johannes Schindelin wrote:
> > [...]
> >> +
> >> +/*
> >> + * this helper function overrides a ROOT_UID with the one provided by
> >> + * an environment variable, do not use unless the original user is
> >> + * root
> >> + */
> >> +static inline void extract_id_from_env(const char *env, uid_t *id)
> >> +{
> >> +    const char *real_uid = getenv(env);
> >> +
> >> +    /* discard any empty values */
> >> +    if (real_uid && *real_uid) {
> >> +            char *endptr;
> >> +            unsigned long env_id;
> >> +            int saved_errno = errno;
> >> +
> >> +            errno = 0;
> >> +            env_id = strtoul(real_uid, &endptr, 10);
> >> +            if (!errno && !*endptr && env_id <= (uid_t)-1)
> >
> > We should not look at `errno` here unless the return value of `strtoul()`
> > indicates that there might have been an error (i.e. when it is
> > `ULONG_MAX`). >
> > Likewise, we need to either initialize `endptr` or only look at it when
> > `strtoul()` succeeded.
>
> I don't think we need to do either of those, and indeed the function you
> suggest below does not do them. The standard guarantees that endptr is
> always set and there is no harm in unconditionally checking errno.

I think the point dscho was trying to make is that while you are
correct that the standard guarantees those two things and
implementation might decide to not do them, we obviously support
systems that are not POSIX.

The irony is that my first confusing attempt to implement this did
that before by explicitly ignoring errno and instead relying in the
"expected overflow/underflow" values to detect the cases we care for
(which is valid UID numbers that are most likely to be uint32_t) and
which was the same thing we got from my original (but hated) atoi.

> > We could side-step all of this, of course, if we simply did this:
> >
> >       euid = getuid();
> >       if (euid == ROOT_UID)
> >               euid = git_env_ulong("SUDO_UID", euid);
>
> That's a nice suggestion, I didn't know that function existed. It means
> we would die() if we could not parse SUDO_UID which I think is
> reasonable (we'd also accept a units suffix an the uid)

which is also why we can't use it, any possibly bogus or suspicious
value we get from SUDO_UID MUST be ignored.

Carlo

  reply	other threads:[~2022-05-06 19:16 UTC|newest]

Thread overview: 170+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-26 18:31 [RFC PATCH] git-compat-util: avoid failing dir ownership checks if running priviledged Carlo Marcelo Arenas Belón
2022-04-26 19:48 ` Derrick Stolee
2022-04-26 19:56   ` Junio C Hamano
2022-04-26 20:10     ` rsbecker
2022-04-26 20:45       ` Carlo Arenas
2022-04-26 21:10         ` Junio C Hamano
2022-04-26 20:12     ` Carlo Arenas
2022-04-26 20:26   ` Carlo Arenas
2022-04-29 16:16   ` Derrick Stolee
2022-04-27  0:05 ` [PATCH] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-04-27  9:33   ` Phillip Wood
2022-04-27 12:30     ` Phillip Wood
2022-04-27 14:15       ` rsbecker
2022-04-27 15:58       ` Carlo Arenas
2022-04-27 16:14         ` Phillip Wood
2022-04-27 18:54           ` Junio C Hamano
2022-04-27 20:59             ` Carlo Arenas
2022-04-27 21:09               ` rsbecker
2022-04-27 21:25               ` Junio C Hamano
2022-04-28 17:56             ` Phillip Wood
2022-04-27 15:38     ` Carlo Arenas
2022-04-27 15:50       ` rsbecker
2022-04-27 16:19       ` Junio C Hamano
2022-04-27 16:45         ` Carlo Arenas
2022-04-27 17:22         ` Phillip Wood
2022-04-27 17:49           ` rsbecker
2022-04-27 17:54             ` Carlo Arenas
2022-04-27 18:05               ` rsbecker
2022-04-27 18:11                 ` Carlo Arenas
2022-04-27 18:16                   ` rsbecker
2022-04-27 16:31       ` Phillip Wood
2022-04-27 16:54         ` Carlo Arenas
2022-04-27 17:28           ` Phillip Wood
2022-04-27 17:49             ` Carlo Arenas
2022-04-27 22:26   ` [RFC PATCH v2] " Carlo Marcelo Arenas Belón
2022-04-27 22:33     ` Junio C Hamano
2022-04-28  3:35     ` [PATCH 0/2] fix `sudo make install` regression in maint Carlo Marcelo Arenas Belón
2022-04-28  3:35       ` [PATCH 1/2] Documentation: explain how safe.directory works when running under sudo Carlo Marcelo Arenas Belón
2022-04-28  5:17         ` Junio C Hamano
2022-04-28  5:58           ` Carlo Arenas
2022-04-28  6:41             ` Junio C Hamano
2022-04-28  3:35       ` [PATCH 2/2] t: add tests for safe.directory when running with sudo Carlo Marcelo Arenas Belón
2022-04-28  5:34         ` Junio C Hamano
2022-04-28  4:57       ` [PATCH 0/2] fix `sudo make install` regression in maint Junio C Hamano
2022-04-28 10:58       ` [PATCH v2 0/3] " Carlo Marcelo Arenas Belón
2022-04-28 10:58         ` [PATCH v2 1/3] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-04-28 18:02           ` Phillip Wood
2022-04-28 18:57             ` Carlo Arenas
2022-04-28 10:58         ` [PATCH v2 2/3] Documentation: explain how safe.directory works when running under sudo Carlo Marcelo Arenas Belón
2022-04-30  6:17           ` Bagas Sanjaya
2022-04-30  6:39             ` Junio C Hamano
2022-04-30 14:15             ` Carlo Marcelo Arenas Belón
2022-04-28 10:58         ` [PATCH v2 3/3] t: add tests for safe.directory when running with sudo Carlo Marcelo Arenas Belón
2022-04-28 16:55           ` Junio C Hamano
2022-04-28 18:08             ` Phillip Wood
2022-04-28 18:12               ` Junio C Hamano
2022-05-06 17:50                 ` Carlo Arenas
2022-05-06 21:43                   ` Junio C Hamano
2022-05-06 22:57                     ` Carlo Arenas
2022-05-06 23:55                       ` Junio C Hamano
2022-05-07 11:57                         ` Carlo Marcelo Arenas Belón
2022-04-28 19:53             ` rsbecker
2022-04-28 20:22               ` Carlo Arenas
2022-04-28 20:43                 ` rsbecker
2022-04-28 20:51                   ` Junio C Hamano
2022-04-28 20:56                   ` Carlo Arenas
2022-04-28 21:55                     ` rsbecker
2022-04-28 22:21                       ` Junio C Hamano
2022-04-28 22:45                         ` rsbecker
2022-04-28 20:46                 ` Junio C Hamano
2022-04-28 20:32               ` Junio C Hamano
2022-04-28 20:40                 ` rsbecker
2022-04-28 20:48                 ` Carlo Arenas
2022-04-28 21:02             ` Carlo Arenas
2022-04-28 21:07               ` Junio C Hamano
2022-04-29  1:24                 ` Carlo Marcelo Arenas Belón
2022-04-29 18:50                   ` Junio C Hamano
2022-04-29 20:05                     ` Carlo Marcelo Arenas Belón
2022-05-02 18:39         ` [RFC PATCH v3 0/3] fix `sudo make install` regression in maint Carlo Marcelo Arenas Belón
2022-05-02 18:39           ` [RFC PATCH v3 1/3] t: document regression git safe.directory when using sudo Carlo Marcelo Arenas Belón
2022-05-02 21:35             ` Junio C Hamano
2022-05-02 23:07               ` Carlo Arenas
2022-05-02 18:39           ` [RFC PATCH v3 2/3] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-05-02 18:39           ` [RFC PATCH v3 3/3] t0034: enhance framework to allow testing more commands under sudo Carlo Marcelo Arenas Belón
2022-05-02 22:10             ` Junio C Hamano
2022-05-03  0:00               ` Carlo Arenas
2022-05-03  6:54         ` [PATCH v3 0/3] fix `sudo make install` regression in maint Carlo Marcelo Arenas Belón
2022-05-03  6:54           ` [PATCH v3 1/3] t: document regression git safe.directory when using sudo Carlo Marcelo Arenas Belón
2022-05-03 14:03             ` Phillip Wood
2022-05-03 15:56               ` Carlo Marcelo Arenas Belón
2022-05-04 11:15                 ` Phillip Wood
2022-05-04 13:02                   ` Carlo Arenas
2022-05-04 14:11                     ` Phillip Wood
2022-05-05 13:44             ` Johannes Schindelin
2022-05-05 14:34               ` Phillip Wood
2022-05-05 15:50               ` Junio C Hamano
2022-05-05 18:33               ` Junio C Hamano
2022-05-05 19:39                 ` Junio C Hamano
2022-05-06 21:03                   ` Carlo Arenas
2022-05-09  8:21                 ` Phillip Wood
2022-05-09 14:51                   ` Carlo Arenas
2022-05-09 15:18                     ` Phillip Wood
2022-05-09 16:01                   ` Junio C Hamano
2022-05-09 16:21                     ` Carlo Arenas
2022-05-06 17:39               ` Carlo Arenas
2022-05-03  6:54           ` [PATCH v3 2/3] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-05-05 14:01             ` Johannes Schindelin
2022-05-05 14:32               ` Phillip Wood
2022-05-06 19:15                 ` Carlo Arenas [this message]
2022-05-06 20:00                   ` Junio C Hamano
2022-05-06 20:22                     ` Carlo Arenas
2022-05-06 20:59                       ` Junio C Hamano
2022-05-06 21:40                         ` Carlo Arenas
2022-05-06 21:07                       ` rsbecker
2022-05-05 16:09               ` Junio C Hamano
2022-05-06 20:02               ` Carlo Arenas
2022-05-03  6:54           ` [PATCH v3 3/3] t0034: enhance framework to allow testing more commands under sudo Carlo Marcelo Arenas Belón
2022-05-03 14:12             ` Phillip Wood
2022-05-03 15:27               ` Junio C Hamano
2022-05-06 16:54               ` Carlo Arenas
2022-05-07 16:35           ` [RFC PATCH v4 0/3] fix `sudo make install` regression in maint Carlo Marcelo Arenas Belón
2022-05-07 16:35             ` [RFC PATCH v4 1/3] t: regression git needs safe.directory when using sudo Carlo Marcelo Arenas Belón
2022-05-07 16:35             ` [RFC PATCH v4 2/3] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-05-07 17:34               ` Junio C Hamano
2022-05-07 18:56                 ` Carlo Marcelo Arenas Belón
2022-05-09 16:54                   ` Junio C Hamano
2022-05-09 17:36                     ` rsbecker
2022-05-09 18:48                     ` Carlo Arenas
2022-05-09 19:16                       ` rsbecker
2022-05-09 19:41                       ` Junio C Hamano
2022-05-07 16:35             ` [RFC PATCH v4 3/3] t0034: add negative tests and allow git init to mostly work under sudo Carlo Marcelo Arenas Belón
2022-05-10 14:17             ` [RFC PATCH v4 0/3] fix `sudo make install` regression in maint Phillip Wood
2022-05-10 15:47               ` Carlo Arenas
2022-05-10 17:46             ` [PATCH " Carlo Marcelo Arenas Belón
2022-05-10 17:46               ` [PATCH v4 1/3] t: regression git needs safe.directory when using sudo Carlo Marcelo Arenas Belón
2022-05-10 22:10                 ` Junio C Hamano
2022-05-10 23:11                   ` Carlo Arenas
2022-05-10 23:44                     ` Junio C Hamano
2022-05-11  0:56                       ` Carlo Arenas
2022-05-11  1:11                         ` Junio C Hamano
2022-05-10 17:46               ` [PATCH v4 2/3] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-05-10 22:57                 ` Junio C Hamano
2022-05-11  7:34                   ` Carlo Arenas
2022-05-11 14:58                     ` Junio C Hamano
2022-05-10 17:46               ` [PATCH v4 3/3] t0034: add negative tests and allow git init to mostly work under sudo Carlo Marcelo Arenas Belón
2022-05-10 23:11                 ` Junio C Hamano
2022-05-10 23:25                   ` Junio C Hamano
2022-05-11 14:04                   ` Carlo Arenas
2022-05-11 15:29                     ` Junio C Hamano
2022-05-13  1:00               ` [PATCH v5 0/4] fix `sudo make install` regression in maint Carlo Marcelo Arenas Belón
2022-05-13  1:00                 ` [PATCH v5 1/4] t: regression git needs safe.directory when using sudo Carlo Marcelo Arenas Belón
2022-06-03 12:12                   ` SZEDER Gábor
2022-05-13  1:00                 ` [PATCH v5 2/4] git-compat-util: avoid failing dir ownership checks if running privileged Carlo Marcelo Arenas Belón
2022-06-03 11:05                   ` SZEDER Gábor
2022-06-03 16:54                     ` Junio C Hamano
2022-06-03 17:34                       ` SZEDER Gábor
2022-05-13  1:00                 ` [PATCH v5 3/4] t0034: add negative tests and allow git init to mostly work under sudo Carlo Marcelo Arenas Belón
2022-05-13  1:20                   ` Junio C Hamano
2022-05-14 14:36                     ` Carlo Arenas
2022-05-15 16:54                       ` Junio C Hamano
2022-05-15 19:21                         ` Carlo Arenas
2022-05-16  5:27                           ` Junio C Hamano
2022-05-16 13:07                             ` Carlo Marcelo Arenas Belón
2022-05-16 16:25                               ` Junio C Hamano
2022-05-13  1:00                 ` [PATCH v5 4/4] git-compat-util: allow root to access both SUDO_UID and root owned Carlo Marcelo Arenas Belón
2022-06-15 14:02                   ` Johannes Schindelin
2022-06-17 14:26                     ` Carlo Arenas
2022-06-17 16:00                       ` Junio C Hamano
2022-06-17 20:23                   ` [PATCH v6] " Carlo Marcelo Arenas Belón
2022-06-17 21:02                     ` Junio C Hamano

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