On 10/03/2021 18:22, Casey Schaufler wrote: > On 3/10/2021 8:09 AM, Mickaël Salaün wrote: >> 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? > >> >> 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@xxxxxxxxxxxxxx/ >> >> 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 >
