From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B23B2C34031 for ; Wed, 19 Feb 2020 02:33:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D30F22B48 for ; Wed, 19 Feb 2020 02:33:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726964AbgBSCdb (ORCPT ); Tue, 18 Feb 2020 21:33:31 -0500 Received: from mail.hallyn.com ([178.63.66.53]:49358 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726799AbgBSCdb (ORCPT ); Tue, 18 Feb 2020 21:33:31 -0500 Received: by mail.hallyn.com (Postfix, from userid 1001) id 9396D46B; Tue, 18 Feb 2020 20:33:26 -0600 (CST) Date: Tue, 18 Feb 2020 20:33:26 -0600 From: "Serge E. Hallyn" To: Christian Brauner Cc: =?iso-8859-1?Q?St=E9phane?= Graber , "Eric W. Biederman" , Aleksa Sarai , Jann Horn , smbarber@chromium.org, Seth Forshee , Alexander Viro , Alexey Dobriyan , Serge Hallyn , James Morris , Kees Cook , Jonathan Corbet , Phil Estes , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, containers@lists.linux-foundation.org, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org Subject: Re: [PATCH v3 01/25] user_namespace: introduce fsid mappings infrastructure Message-ID: <20200219023326.GA19144@mail.hallyn.com> References: <20200218143411.2389182-1-christian.brauner@ubuntu.com> <20200218143411.2389182-2-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200218143411.2389182-2-christian.brauner@ubuntu.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Tue, Feb 18, 2020 at 03:33:47PM +0100, Christian Brauner wrote: > This introduces the infrastructure to setup fsid mappings which will be used in > later patches. > All new code depends on CONFIG_USER_NS_FSID=y. It currently defaults to "N". > If CONFIG_USER_NS_FSID is not set, no new code is added. > > In this patch fsuid_m_show() and fsgid_m_show() are introduced. They are > identical to uid_m_show() and gid_m_show() until we introduce from_kfsuid() and > from_kfsgid() in a follow-up patch. > > Signed-off-by: Christian Brauner Acked-by: Serge Hallyn > --- > /* v2 */ > - Randy Dunlap : > - Fix typo in USER_NS_FSID kconfig documentation. > > /* v3 */ > unchanged > --- > include/linux/user_namespace.h | 10 +++ > init/Kconfig | 11 +++ > kernel/user.c | 22 ++++++ > kernel/user_namespace.c | 122 +++++++++++++++++++++++++++++++++ > 4 files changed, 165 insertions(+) > > diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h > index 6ef1c7109fc4..e44742b0cf8a 100644 > --- a/include/linux/user_namespace.h > +++ b/include/linux/user_namespace.h > @@ -56,6 +56,10 @@ enum ucount_type { > struct user_namespace { > struct uid_gid_map uid_map; > struct uid_gid_map gid_map; > +#ifdef CONFIG_USER_NS_FSID > + struct uid_gid_map fsuid_map; > + struct uid_gid_map fsgid_map; > +#endif > struct uid_gid_map projid_map; > atomic_t count; > struct user_namespace *parent; > @@ -127,6 +131,12 @@ struct seq_operations; > extern const struct seq_operations proc_uid_seq_operations; > extern const struct seq_operations proc_gid_seq_operations; > extern const struct seq_operations proc_projid_seq_operations; > +#ifdef CONFIG_USER_NS_FSID > +extern const struct seq_operations proc_fsuid_seq_operations; > +extern const struct seq_operations proc_fsgid_seq_operations; > +extern ssize_t proc_fsuid_map_write(struct file *, const char __user *, size_t, loff_t *); > +extern ssize_t proc_fsgid_map_write(struct file *, const char __user *, size_t, loff_t *); > +#endif > extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *); > extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *); > extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *); > diff --git a/init/Kconfig b/init/Kconfig > index cfee56c151f1..d4d0beeba48f 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1111,6 +1111,17 @@ config USER_NS > > If unsure, say N. > > +config USER_NS_FSID > + bool "User namespace fsid mappings" > + depends on USER_NS > + default n > + help > + This allows containers to alter their filesystem id mappings. > + With this containers with different id mappings can still share > + the same filesystem. > + > + If unsure, say N. > + > config PID_NS > bool "PID Namespaces" > default y > diff --git a/kernel/user.c b/kernel/user.c > index 5235d7f49982..2ccaea9b810b 100644 > --- a/kernel/user.c > +++ b/kernel/user.c > @@ -55,6 +55,28 @@ struct user_namespace init_user_ns = { > }, > }, > }, > +#ifdef CONFIG_USER_NS_FSID > + .fsuid_map = { > + .nr_extents = 1, > + { > + .extent[0] = { > + .first = 0, > + .lower_first = 0, > + .count = 4294967295U, > + }, > + }, > + }, > + .fsgid_map = { > + .nr_extents = 1, > + { > + .extent[0] = { > + .first = 0, > + .lower_first = 0, > + .count = 4294967295U, > + }, > + }, > + }, > +#endif > .count = ATOMIC_INIT(3), > .owner = GLOBAL_ROOT_UID, > .group = GLOBAL_ROOT_GID, > diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c > index 8eadadc478f9..cbdf456f95f0 100644 > --- a/kernel/user_namespace.c > +++ b/kernel/user_namespace.c > @@ -191,6 +191,16 @@ static void free_user_ns(struct work_struct *work) > kfree(ns->projid_map.forward); > kfree(ns->projid_map.reverse); > } > +#ifdef CONFIG_USER_NS_FSID > + if (ns->fsgid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { > + kfree(ns->fsgid_map.forward); > + kfree(ns->fsgid_map.reverse); > + } > + if (ns->fsuid_map.nr_extents > UID_GID_MAP_MAX_BASE_EXTENTS) { > + kfree(ns->fsuid_map.forward); > + kfree(ns->fsuid_map.reverse); > + } > +#endif > retire_userns_sysctls(ns); > key_free_user_ns(ns); > ns_free_inum(&ns->ns); > @@ -637,6 +647,50 @@ static int projid_m_show(struct seq_file *seq, void *v) > return 0; > } > > +#ifdef CONFIG_USER_NS_FSID > +static int fsuid_m_show(struct seq_file *seq, void *v) > +{ > + struct user_namespace *ns = seq->private; > + struct uid_gid_extent *extent = v; > + struct user_namespace *lower_ns; > + uid_t lower; > + > + lower_ns = seq_user_ns(seq); > + if ((lower_ns == ns) && lower_ns->parent) > + lower_ns = lower_ns->parent; > + > + lower = from_kuid(lower_ns, KUIDT_INIT(extent->lower_first)); > + > + seq_printf(seq, "%10u %10u %10u\n", > + extent->first, > + lower, > + extent->count); > + > + return 0; > +} > + > +static int fsgid_m_show(struct seq_file *seq, void *v) > +{ > + struct user_namespace *ns = seq->private; > + struct uid_gid_extent *extent = v; > + struct user_namespace *lower_ns; > + gid_t lower; > + > + lower_ns = seq_user_ns(seq); > + if ((lower_ns == ns) && lower_ns->parent) > + lower_ns = lower_ns->parent; > + > + lower = from_kgid(lower_ns, KGIDT_INIT(extent->lower_first)); > + > + seq_printf(seq, "%10u %10u %10u\n", > + extent->first, > + lower, > + extent->count); > + > + return 0; > +} > +#endif > + > static void *m_start(struct seq_file *seq, loff_t *ppos, > struct uid_gid_map *map) > { > @@ -674,6 +728,22 @@ static void *projid_m_start(struct seq_file *seq, loff_t *ppos) > return m_start(seq, ppos, &ns->projid_map); > } > > +#ifdef CONFIG_USER_NS_FSID > +static void *fsuid_m_start(struct seq_file *seq, loff_t *ppos) > +{ > + struct user_namespace *ns = seq->private; > + > + return m_start(seq, ppos, &ns->fsuid_map); > +} > + > +static void *fsgid_m_start(struct seq_file *seq, loff_t *ppos) > +{ > + struct user_namespace *ns = seq->private; > + > + return m_start(seq, ppos, &ns->fsgid_map); > +} > +#endif > + > static void *m_next(struct seq_file *seq, void *v, loff_t *pos) > { > (*pos)++; > @@ -706,6 +776,22 @@ const struct seq_operations proc_projid_seq_operations = { > .show = projid_m_show, > }; > > +#ifdef CONFIG_USER_NS_FSID > +const struct seq_operations proc_fsuid_seq_operations = { > + .start = fsuid_m_start, > + .stop = m_stop, > + .next = m_next, > + .show = fsuid_m_show, > +}; > + > +const struct seq_operations proc_fsgid_seq_operations = { > + .start = fsgid_m_start, > + .stop = m_stop, > + .next = m_next, > + .show = fsgid_m_show, > +}; > +#endif > + > static bool mappings_overlap(struct uid_gid_map *new_map, > struct uid_gid_extent *extent) > { > @@ -1081,6 +1167,42 @@ ssize_t proc_projid_map_write(struct file *file, const char __user *buf, > &ns->projid_map, &ns->parent->projid_map); > } > > +#ifdef CONFIG_USER_NS_FSID > +ssize_t proc_fsuid_map_write(struct file *file, const char __user *buf, > + size_t size, loff_t *ppos) > +{ > + struct seq_file *seq = file->private_data; > + struct user_namespace *ns = seq->private; > + struct user_namespace *seq_ns = seq_user_ns(seq); > + > + if (!ns->parent) > + return -EPERM; > + > + if ((seq_ns != ns) && (seq_ns != ns->parent)) > + return -EPERM; > + > + return map_write(file, buf, size, ppos, CAP_SETUID, &ns->fsuid_map, > + &ns->parent->fsuid_map); > +} > + > +ssize_t proc_fsgid_map_write(struct file *file, const char __user *buf, > + size_t size, loff_t *ppos) > +{ > + struct seq_file *seq = file->private_data; > + struct user_namespace *ns = seq->private; > + struct user_namespace *seq_ns = seq_user_ns(seq); > + > + if (!ns->parent) > + return -EPERM; > + > + if ((seq_ns != ns) && (seq_ns != ns->parent)) > + return -EPERM; > + > + return map_write(file, buf, size, ppos, CAP_SETGID, &ns->fsgid_map, > + &ns->parent->fsgid_map); > +} > +#endif > + > static bool new_idmap_permitted(const struct file *file, > struct user_namespace *ns, int cap_setid, > struct uid_gid_map *new_map) > -- > 2.25.0