Re: [PATCH v1 0/1] Unprivileged chroot
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From: Mickaël Salaün <mic@digikod.net>
Date: 2021-03-10 18:18:38
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On 10/03/2021 18:22, Casey Schaufler wrote:
On 3/10/2021 8:09 AM, Mickaël Salaün wrote:quoted
Hi, The chroot system call is currently limited to be used by processes with the CAP_SYS_CHROOT capability. This protects against malicious procesess willing to trick SUID-like binaries. The following patch allows unprivileged users to safely use chroot(2).Mount namespaces have pretty well obsoleted chroot(). CAP_SYS_CHROOT is one of the few fine grained capabilities. We're still finding edge cases (e.g. ptrace) where no_new_privs is imperfect. I doesn't seem that there is a compelling reason to remove the privilege requirement on chroot().
What is the link between chroot and ptrace? What is interesting with CAP_SYS_CHROOT?
quoted
This patch is a follow-up of a previous one sent by Andy Lutomirski some time ago: https://lore.kernel.org/lkml/0e2f0f54e19bff53a3739ecfddb4ffa9a6dbde4d.1327858005.git.luto@amacapital.net/ (local) This patch can be applied on top of v5.12-rc2 . I would really appreciate constructive reviews. Regards, Mickaël Salaün (1): fs: Allow no_new_privs tasks to call chroot(2) fs/open.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 61 insertions(+), 3 deletions(-) base-commit: a38fd8748464831584a19438cbb3082b5a2dab15