From: Junio C Hamano <gitster@pobox.com>
To: "Carlo Marcelo Arenas Belón" <carenas@gmail.com>
Cc: git@vger.kernel.org, bagasdotme@gmail.com,
phillip.wood123@gmail.com, Johannes.Schindelin@gmx.de,
"Guy Maurel" <guy.j@maurel.de>,
"SZEDER Gábor" <szeder.dev@gmail.com>,
"Randall Becker" <rsbecker@nexbridge.com>
Subject: Re: [RFC PATCH v4 2/3] git-compat-util: avoid failing dir ownership checks if running privileged
Date: Mon, 09 May 2022 09:54:52 -0700 [thread overview]
Message-ID: <xmqq1qx2ejdv.fsf@gitster.g> (raw)
In-Reply-To: <20220507185624.k5n6xihvzcuuj3vt@carlos-mbp.lan> ("Carlo Marcelo Arenas Belón"'s message of "Sat, 7 May 2022 11:56:24 -0700")
Carlo Marcelo Arenas Belón <carenas@gmail.com> writes:
>> In exchange, the only attack scenario the code prevents is this,
>> IIUC.
>>
>> * You, the aspiring cracker, are a user not allowed to run "sudo" on
>> the box, and you know your uid is 1000
>>
>> * You look for another user, a potential victim, whose uid is 1000
>> modulo 65536 (if your uid_t is 16-bit) and who can run "sudo" on
>> the box.
>>
>> * You prepare a malicious repository, invite that user there and
>> ask them to run "sudo something" there.
>>
>> I'd say such an attack vector is not likely,...
Sorry, I was totally wrong here.
It is not just "not likely", but such an attack, with a potential
victim not futzing with SUDO_UID environment themselves, would not
work at all. The value of SUDO_UID and the original uid of the
potential victim by definition should fit in the uid_t type. So if
you, the aspiring cracker, have UID 1000, nobody else on the system
has UID that is congruent modulo uid_t and wrap-around attack does
not exist. As long as the type we use to read SUDO_UID string into
a variable is not narrower than uid_t, there.
Of course you can tell any user who runs "sudo" to set SUDO_UID to
1000 + 64k and cause wrap-around, but then you can tell them to set
SUDO_UID to 1000 without relying on wrap-around and have the same
effect. So, let's stop worrying about this bogus scenario.
As to the "we can break compilation with -Wsign-compare on a system
with signed uid_t", I agree that is true if we have
env_id <= (uid_t) -1
there. But I am not sure if that is the most effective way to smoke
out platforms where this code has trouble working correctly. Also,
I would think that a system with signed uid_t is a possibility, but
a user with a negative UID?
I do not think even nobody4 was negative ;-)
next prev parent reply other threads:[~2022-05-09 16:56 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
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 [this message]
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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