From: "Serge E. Hallyn" <serge@hallyn.com>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: "Stéphane Graber" <stgraber@ubuntu.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Jann Horn" <jannh@google.com>,
smbarber@chromium.org,
"Seth Forshee" <seth.forshee@canonical.com>,
"Alexander Viro" <viro@zeniv.linux.org.uk>,
"Alexey Dobriyan" <adobriyan@gmail.com>,
"Serge Hallyn" <serge@hallyn.com>,
"James Morris" <jmorris@namei.org>,
"Kees Cook" <keescook@chromium.org>,
"Jonathan Corbet" <corbet@lwn.net>,
"Phil Estes" <estesp@gmail.com>,
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
Date: Tue, 18 Feb 2020 20:33:26 -0600 [thread overview]
Message-ID: <20200219023326.GA19144@mail.hallyn.com> (raw)
In-Reply-To: <20200218143411.2389182-2-christian.brauner@ubuntu.com>
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 <christian.brauner@ubuntu.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
> ---
> /* v2 */
> - Randy Dunlap <rdunlap@infradead.org>:
> - 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
next prev parent reply other threads:[~2020-02-19 2:33 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 14:33 [PATCH v3 00/25] user_namespace: introduce fsid mappings Christian Brauner
2020-02-18 14:33 ` [PATCH v3 01/25] user_namespace: introduce fsid mappings infrastructure Christian Brauner
2020-02-19 2:33 ` Serge E. Hallyn [this message]
2020-02-18 14:33 ` [PATCH v3 02/25] proc: add /proc/<pid>/fsuid_map Christian Brauner
2020-02-19 2:33 ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 03/25] proc: add /proc/<pid>/fsgid_map Christian Brauner
2020-02-19 2:33 ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 04/25] fsuidgid: add fsid mapping helpers Christian Brauner
2020-02-18 14:33 ` [PATCH v3 05/25] user_namespace: refactor map_write() Christian Brauner
2020-02-19 2:35 ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 06/25] user_namespace: make map_write() support fsid mappings Christian Brauner
2020-02-19 16:18 ` Jann Horn
2020-02-18 14:33 ` [PATCH v3 07/25] proc: task_state(): use from_kfs{g,u}id_munged Christian Brauner
2020-02-19 2:36 ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 08/25] cred: add kfs{g,u}id Christian Brauner
2020-02-18 14:33 ` [PATCH v3 09/25] fs: add is_userns_visible() helper Christian Brauner
2020-02-19 2:42 ` Serge E. Hallyn
2020-02-19 12:06 ` Christian Brauner
2020-02-19 17:18 ` Andy Lutomirski
2020-02-20 14:26 ` Serge E. Hallyn
2020-02-18 14:33 ` [PATCH v3 10/25] namei: may_{o_}create(): handle fsid mappings Christian Brauner
2020-02-18 14:33 ` [PATCH v3 11/25] inode: inode_owner_or_capable(): " Christian Brauner
2020-02-18 22:25 ` Christoph Hellwig
2020-02-19 12:29 ` Christian Brauner
2020-02-18 14:33 ` [PATCH v3 12/25] capability: privileged_wrt_inode_uidgid(): " Christian Brauner
2020-02-18 14:33 ` [PATCH v3 13/25] stat: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 14/25] open: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 15/25] posix_acl: " Christian Brauner
2020-02-18 22:26 ` Christoph Hellwig
2020-02-19 12:56 ` Christian Brauner
2020-02-18 14:34 ` [PATCH v3 16/25] attr: notify_change(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 17/25] commoncap: cap_bprm_set_creds(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 18/25] commoncap: cap_task_fix_setuid(): " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 19/25] commoncap: handle fsid mappings with vfs caps Christian Brauner
2020-02-19 15:53 ` Jann Horn
2020-02-18 14:34 ` [PATCH v3 20/25] exec: bprm_fill_uid(): handle fsid mappings Christian Brauner
2020-02-18 14:34 ` [PATCH v3 21/25] ptrace: adapt ptrace_may_access() to always uses unmapped fsids Christian Brauner
2020-02-18 14:34 ` [PATCH v3 22/25] devpts: handle fsid mappings Christian Brauner
2020-02-18 14:34 ` [PATCH v3 23/25] keys: " Christian Brauner
2020-02-18 14:34 ` [PATCH v3 24/25] sys: handle fsid mappings in set*id() calls Christian Brauner
2020-02-19 15:42 ` Jann Horn
2020-02-18 14:34 ` [PATCH v3 25/25] selftests: add simple fsid mapping selftests Christian Brauner
2020-02-18 23:50 ` [PATCH v3 00/25] user_namespace: introduce fsid mappings James Bottomley
2020-02-19 12:27 ` Christian Brauner
2020-02-19 15:36 ` James Bottomley
2020-02-19 15:33 ` Jann Horn
2020-02-19 19:35 ` Serge E. Hallyn
2020-02-19 21:48 ` Serge E. Hallyn
2020-02-19 21:56 ` Tycho Andersen
2020-02-27 19:33 ` Josef Bacik
2020-03-02 14:34 ` Serge E. Hallyn
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