From: Christian Brauner <christian.brauner@ubuntu.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
linux-fsdevel@vger.kernel.org
Cc: "John Johansen" <john.johansen@canonical.com>,
"James Morris" <jmorris@namei.org>,
"Mimi Zohar" <zohar@linux.ibm.com>,
"Dmitry Kasatkin" <dmitry.kasatkin@gmail.com>,
"Stephen Smalley" <stephen.smalley.work@gmail.com>,
"Casey Schaufler" <casey@schaufler-ca.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Andreas Dilger" <adilger.kernel@dilger.ca>,
"OGAWA Hirofumi" <hirofumi@mail.parknet.co.jp>,
"Geoffrey Thomas" <geofft@ldpreload.com>,
"Mrunal Patel" <mpatel@redhat.com>,
"Josh Triplett" <josh@joshtriplett.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Amir Goldstein" <amir73il@gmail.com>,
"Miklos Szeredi" <miklos@szeredi.hu>,
"Theodore Tso" <tytso@mit.edu>, "Alban Crequy" <alban@kinvolk.io>,
"Tycho Andersen" <tycho@tycho.ws>,
"David Howells" <dhowells@redhat.com>,
"James Bottomley" <James.Bottomley@hansenpartnership.com>,
"Jann Horn" <jannh@google.com>,
"Seth Forshee" <seth.forshee@canonical.com>,
"Stéphane Graber" <stgraber@ubuntu.com>,
"Aleksa Sarai" <cyphar@cyphar.com>,
"Lennart Poettering" <lennart@poettering.net>,
"Eric W. Biederman" <ebiederm@xmission.com>,
smbarber@chromium.org, "Phil Estes" <estesp@gmail.com>,
"Serge Hallyn" <serge@hallyn.com>,
"Kees Cook" <keescook@chromium.org>,
"Todd Kjos" <tkjos@google.com>,
"Jonathan Corbet" <corbet@lwn.net>,
containers@lists.linux-foundation.org,
linux-security-module@vger.kernel.org, linux-api@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-unionfs@vger.kernel.org,
linux-audit@redhat.com, linux-integrity@vger.kernel.org,
selinux@vger.kernel.org,
"Christian Brauner" <christian.brauner@ubuntu.com>
Subject: [PATCH 19/34] namei: add lookup helpers with idmapped mounts aware permission checking
Date: Thu, 29 Oct 2020 01:32:37 +0100 [thread overview]
Message-ID: <20201029003252.2128653-20-christian.brauner@ubuntu.com> (raw)
In-Reply-To: <20201029003252.2128653-1-christian.brauner@ubuntu.com>
The lookup_one_len(), lookup_one_len_unlocked(), and lookup_positive_unlocked()
helpers are used by filesystems targeted in this first iteration to lookup
dentries if the caller is privileged over the inode of the base dentry. Add
three new helpers lookup_one_len_mapped(), lookup_one_len_mapped_unlocked(),
and lookup_one_len_mapped_unlocked() to handle idmapped mounts. If the inode is
accessed through an idmapped mount it is mapped according to the mount's user
namespace. Afterwards the permissions checks are identical to non-idmapped
mounts. If the initial user namespace is passed all mapping operations are a
nop so non-idmapped mounts will not see a change in behavior and will also not
see any performance impact. It also means that the non-idmapped-mount aware
helpers can be implemented on top of their idmapped-mount aware counterparts by
passing the initial user namespace.
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
fs/namei.c | 47 ++++++++++++++++++++++++++++++++-----------
include/linux/namei.h | 6 ++++++
2 files changed, 41 insertions(+), 12 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index a8a3de936cfc..7901ea09e80e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2517,8 +2517,9 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
}
EXPORT_SYMBOL(vfs_path_lookup);
-static int lookup_one_len_common(const char *name, struct dentry *base,
- int len, struct qstr *this)
+static int lookup_one_len_common(const char *name, struct dentry *base, int len,
+ struct qstr *this,
+ struct user_namespace *mnt_user_ns)
{
this->name = name;
this->len = len;
@@ -2546,7 +2547,7 @@ static int lookup_one_len_common(const char *name, struct dentry *base,
return err;
}
- return inode_permission(base->d_inode, MAY_EXEC);
+ return mapped_inode_permission(mnt_user_ns, base->d_inode, MAY_EXEC);
}
/**
@@ -2570,7 +2571,7 @@ struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len
WARN_ON_ONCE(!inode_is_locked(base->d_inode));
- err = lookup_one_len_common(name, base, len, &this);
+ err = lookup_one_len_common(name, base, len, &this, &init_user_ns);
if (err)
return ERR_PTR(err);
@@ -2589,7 +2590,8 @@ EXPORT_SYMBOL(try_lookup_one_len);
*
* The caller must hold base->i_mutex.
*/
-struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
+struct dentry *lookup_one_len_mapped(const char *name, struct dentry *base, int len,
+ struct user_namespace *mnt_user_ns)
{
struct dentry *dentry;
struct qstr this;
@@ -2597,13 +2599,19 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
WARN_ON_ONCE(!inode_is_locked(base->d_inode));
- err = lookup_one_len_common(name, base, len, &this);
+ err = lookup_one_len_common(name, base, len, &this, mnt_user_ns);
if (err)
return ERR_PTR(err);
dentry = lookup_dcache(&this, base, 0);
return dentry ? dentry : __lookup_slow(&this, base, 0);
}
+EXPORT_SYMBOL(lookup_one_len_mapped);
+
+struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
+{
+ return lookup_one_len_mapped(name, base, len, &init_user_ns);
+}
EXPORT_SYMBOL(lookup_one_len);
/**
@@ -2618,14 +2626,14 @@ EXPORT_SYMBOL(lookup_one_len);
* Unlike lookup_one_len, it should be called without the parent
* i_mutex held, and will take the i_mutex itself if necessary.
*/
-struct dentry *lookup_one_len_unlocked(const char *name,
- struct dentry *base, int len)
+struct dentry *lookup_one_len_mapped_unlocked(const char *name, struct dentry *base,
+ int len, struct user_namespace *mnt_user_ns)
{
struct qstr this;
int err;
struct dentry *ret;
- err = lookup_one_len_common(name, base, len, &this);
+ err = lookup_one_len_common(name, base, len, &this, mnt_user_ns);
if (err)
return ERR_PTR(err);
@@ -2634,6 +2642,13 @@ struct dentry *lookup_one_len_unlocked(const char *name,
ret = lookup_slow(&this, base, 0);
return ret;
}
+EXPORT_SYMBOL(lookup_one_len_mapped_unlocked);
+
+struct dentry *lookup_one_len_unlocked(const char *name,
+ struct dentry *base, int len)
+{
+ return lookup_one_len_mapped_unlocked(name, base, len, &init_user_ns);
+}
EXPORT_SYMBOL(lookup_one_len_unlocked);
/*
@@ -2644,16 +2659,24 @@ EXPORT_SYMBOL(lookup_one_len_unlocked);
* need to be very careful; pinned positives have ->d_inode stable, so
* this one avoids such problems.
*/
-struct dentry *lookup_positive_unlocked(const char *name,
- struct dentry *base, int len)
+struct dentry *lookup_positive_mapped_unlocked(const char *name,
+ struct dentry *base, int len,
+ struct user_namespace *mnt_user_ns)
{
- struct dentry *ret = lookup_one_len_unlocked(name, base, len);
+ struct dentry *ret = lookup_one_len_mapped_unlocked(name, base, len, mnt_user_ns);
if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) {
dput(ret);
ret = ERR_PTR(-ENOENT);
}
return ret;
}
+EXPORT_SYMBOL(lookup_positive_mapped_unlocked);
+
+struct dentry *lookup_positive_unlocked(const char *name,
+ struct dentry *base, int len)
+{
+ return lookup_positive_mapped_unlocked(name, base, len, &init_user_ns);
+}
EXPORT_SYMBOL(lookup_positive_unlocked);
#ifdef CONFIG_UNIX98_PTYS
diff --git a/include/linux/namei.h b/include/linux/namei.h
index a4bb992623c4..42dbe4c2653a 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -68,8 +68,14 @@ extern struct dentry *kern_path_locked(const char *, struct path *);
extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
+extern struct dentry *lookup_one_len_mapped(const char *, struct dentry *, int,
+ struct user_namespace *);
extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
+extern struct dentry *lookup_one_len_mapped_unlocked(const char *, struct dentry *,
+ int, struct user_namespace *);
extern struct dentry *lookup_positive_unlocked(const char *, struct dentry *, int);
+extern struct dentry *lookup_positive_mapped_unlocked(const char *, struct dentry *,
+ int, struct user_namespace *);
extern int follow_down_one(struct path *);
extern int follow_down(struct path *);
--
2.29.0
next prev parent reply other threads:[~2020-10-29 0:38 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 0:32 [PATCH 00/34] fs: idmapped mounts Christian Brauner
2020-10-29 0:32 ` [PATCH 01/34] namespace: take lock_mount_hash() directly when changing flags Christian Brauner
2020-11-01 14:41 ` Christoph Hellwig
2020-11-02 13:33 ` Christian Brauner
2020-10-29 0:32 ` [PATCH 02/34] namespace: only take read lock in do_reconfigure_mnt() Christian Brauner
2020-10-29 0:32 ` [PATCH 03/34] fs: add mount_setattr() Christian Brauner
2020-11-01 14:42 ` Christoph Hellwig
2020-11-02 13:34 ` Christian Brauner
2020-10-29 0:32 ` [PATCH 04/34] tests: add mount_setattr() selftests Christian Brauner
2020-10-29 0:32 ` [PATCH 05/34] fs: introduce MOUNT_ATTR_IDMAP Christian Brauner
2020-11-01 14:45 ` Christoph Hellwig
2020-11-02 13:29 ` Christian Brauner
2020-10-29 0:32 ` [PATCH 06/34] fs: add id translation helpers Christian Brauner
2020-11-01 14:46 ` Christoph Hellwig
2020-11-02 13:25 ` Christian Brauner
2020-10-29 0:32 ` [PATCH 07/34] capability: handle idmapped mounts Christian Brauner
2020-11-01 14:48 ` Christoph Hellwig
2020-11-02 13:23 ` Christian Brauner
2020-10-29 0:32 ` [PATCH 08/34] namei: add idmapped mount aware permission helpers Christian Brauner
2020-10-29 0:32 ` [PATCH 09/34] inode: add idmapped mount aware init and " Christian Brauner
2020-10-29 0:32 ` [PATCH 10/34] attr: handle idmapped mounts Christian Brauner
2020-10-29 0:32 ` [PATCH 11/34] acl: " Christian Brauner
2020-10-29 0:32 ` [PATCH 12/34] xattr: " Christian Brauner
2020-10-29 0:32 ` [PATCH 13/34] selftests: add idmapped mounts xattr selftest Christian Brauner
2020-10-29 0:32 ` [PATCH 14/34] commoncap: handle idmapped mounts Christian Brauner
2020-10-29 0:32 ` [PATCH 15/34] stat: add mapped_generic_fillattr() Christian Brauner
2020-10-29 0:32 ` [PATCH 16/34] namei: handle idmapped mounts in may_*() helpers Christian Brauner
2020-10-29 0:32 ` [PATCH 17/34] namei: introduce struct renamedata Christian Brauner
2020-10-29 0:32 ` [PATCH 18/34] namei: prepare for idmapped mounts Christian Brauner
2020-10-29 0:32 ` Christian Brauner [this message]
2020-10-29 0:32 ` [PATCH 20/34] open: handle idmapped mounts in do_truncate() Christian Brauner
2020-10-29 0:32 ` [PATCH 21/34] open: handle idmapped mounts Christian Brauner
2020-10-29 0:32 ` [PATCH 22/34] af_unix: " Christian Brauner
2020-10-29 0:32 ` [PATCH 23/34] utimes: " Christian Brauner
2020-10-29 0:32 ` [PATCH 24/34] would_dump: " Christian Brauner
2020-10-29 0:32 ` [PATCH 25/34] exec: " Christian Brauner
2020-10-29 0:32 ` [PATCH 26/34] fs: add helpers for idmap mounts Christian Brauner
2020-10-29 0:32 ` [PATCH 27/34] apparmor: handle idmapped mounts Christian Brauner
2020-10-29 0:32 ` [PATCH 28/34] audit: " Christian Brauner
2020-10-29 0:32 ` [PATCH 29/34] ima: " Christian Brauner
2020-10-29 0:32 ` [PATCH 30/34] ext4: support " Christian Brauner
2020-10-29 0:32 ` [PATCH 31/34] expfs: handle " Christian Brauner
2020-10-29 0:32 ` [PATCH 32/34] overlayfs: handle idmapped lower directories Christian Brauner
2020-10-30 11:10 ` Amir Goldstein
2020-10-30 11:52 ` Christian Brauner
2020-10-29 0:32 ` [PATCH 33/34] overlayfs: handle idmapped merged mounts Christian Brauner
2020-10-30 9:57 ` Amir Goldstein
2020-10-29 0:32 ` [PATCH 34/34] fat: handle idmapped mounts Christian Brauner
2020-10-29 2:27 ` [PATCH 00/34] fs: " Dave Chinner
2020-10-29 16:19 ` Christian Brauner
2020-10-29 7:20 ` Sargun Dhillon
2020-10-29 15:47 ` Eric W. Biederman
2020-10-29 15:51 ` Aleksa Sarai
2020-10-29 16:37 ` Eric W. Biederman
2020-10-30 2:18 ` Serge E. Hallyn
2020-10-30 15:07 ` Seth Forshee
2020-10-30 16:03 ` Serge E. Hallyn
2020-11-03 14:10 ` Alban Crequy
2020-10-29 16:05 ` Lennart Poettering
2020-10-29 16:36 ` Sargun Dhillon
2020-10-29 16:54 ` Eric W. Biederman
[not found] ` <20201029161231.GA108315@cisco>
2020-10-29 16:23 ` Serge E. Hallyn
2020-10-29 16:44 ` Eric W. Biederman
2020-10-29 18:04 ` Stéphane Graber
2020-10-29 21:58 ` Andy Lutomirski
2020-10-30 12:01 ` Christian Brauner
2020-10-30 16:17 ` Serge E. Hallyn
2020-10-31 17:43 ` Andy Lutomirski
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