From: Al Viro <viro@zeniv.linux.org.uk>
To: linux-fsdevel@vger.kernel.org
Cc: Tycho Andersen <tycho@tycho.pizza>,
Andrei Vagin <avagin@google.com>, Andrei Vagin <avagin@gmail.com>,
Christian Brauner <brauner@kernel.org>,
Pavel Tikhomirov <snorcht@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
criu@lists.linux.dev, Linux API <linux-api@vger.kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: [RFC][CFT] selftest for permission checks in mount propagation changes
Date: Thu, 14 Aug 2025 07:37:45 +0100 [thread overview]
Message-ID: <20250814063745.GP222315@ZenIV> (raw)
In-Reply-To: <20250814055702.GO222315@ZenIV>
> void do_unshare(void)
> {
> FILE *f;
> uid_t uid = geteuid();
> gid_t gid = getegid();
> unshare(CLONE_NEWNS|CLONE_NEWUSER);
> f = fopen("/proc/self/uid_map", "w");
> fprintf(f, "0 %d 1", uid);
> fclose(f);
> f = fopen("/proc/self/setgroups", "w");
> fprintf(f, "deny");
> fclose(f);
> f = fopen("/proc/self/gid_map", "w");
> fprintf(f, "0 %d 1", gid);
> fclose(f);
> mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL);
> }
This obviously needs error checking - in this form it won't do
anything good without userns enabled (coredump on the first
fprintf() in there, since there won't be /proc/self/uid_map);
should probably just report CLONE_NEWUSER failure, warn about
skipped tests, fall back to unshare(CLONE_NEWNS) and skip
everything in in_child()...
next prev parent reply other threads:[~2025-08-14 6:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CANaxB-xXgW1FEj6ydBT2=cudTbP=fX6x8S53zNkWcw1poL=L2A@mail.gmail.com>
[not found] ` <20250724230052.GW2580412@ZenIV>
2025-07-26 17:12 ` do_change_type(): refuse to operate on unmounted/not ours mounts Andrei Vagin
2025-07-26 17:53 ` Al Viro
2025-07-26 21:01 ` Andrei Vagin
2025-07-31 2:40 ` Pavel Tikhomirov
2025-07-31 7:53 ` Christian Brauner
2025-07-31 8:11 ` Pavel Tikhomirov
2025-08-13 18:56 ` Al Viro
2025-08-13 19:09 ` Tycho Andersen
2025-08-13 19:41 ` Al Viro
2025-08-14 4:08 ` Pavel Tikhomirov
2025-08-14 4:42 ` Al Viro
2025-08-14 5:51 ` [PATCH][RFC][CFT] use uniform permission checks for all mount propagation changes Al Viro
2025-08-14 5:57 ` [RFC][CFT] selftest for permission checks in " Al Viro
2025-08-14 6:37 ` Al Viro [this message]
2025-08-14 7:07 ` do_change_type(): refuse to operate on unmounted/not ours mounts Pavel Tikhomirov
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