From patchwork Mon Jan 4 18:03:55 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Seth Forshee X-Patchwork-Id: 7949571 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 00DC99F1C0 for ; Mon, 4 Jan 2016 18:08:43 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BDBFD20138 for ; Mon, 4 Jan 2016 18:08:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69B5A2010B for ; Mon, 4 Jan 2016 18:08:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753006AbcADSId (ORCPT ); Mon, 4 Jan 2016 13:08:33 -0500 Received: from mail-io0-f172.google.com ([209.85.223.172]:36739 "EHLO mail-io0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751835AbcADSEq (ORCPT ); Mon, 4 Jan 2016 13:04:46 -0500 Received: by mail-io0-f172.google.com with SMTP id o67so442133352iof.3 for ; Mon, 04 Jan 2016 10:04:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=1kLesQiG4AKuxDOb1LIboPaKxqwcc854YtYJg8McPPg=; b=ufcEPgwzkpphtLm+x1SZWhiFM7sSYpqxDQE8Gj/O3zN0saWIQrkG0oPWW0cFW+ke+7 NN5+0Ol+43TbF82OSKY9EzC+sZJmRJzRDx6NGqcJl1TDpHYTJO+IODmRPsOA5O+mIsU+ noB7Wcazn6rTjjqJbQKBEMgw3i2cv6NEhWBSPgnekBRTLTpN1a7mSTlFPr/isr15efCq l8Zu8EaGyexaUsaieEtLV/n9DArO+HBiQzQ+ARLIptSWK5MGFl3dnvreItJK1d2bOWPK W3G7MFzO99zn4RmbJP2pqJgwsKB50NBv3wpRwW2We2+k2uGRiFDXch10c1Dd8mdl+Sbn ZcKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=1kLesQiG4AKuxDOb1LIboPaKxqwcc854YtYJg8McPPg=; b=WEJp1lGbXdbAKNLOGbugm2dEDfdomjoZ0xJP6+cxyh9y9o5DP2dnNyJnG4qV9nSucv kwFQtezEFbdd12iQiuXMIa3h7eM4yUzHSlks7wzIuwkL7UnQjpnlC11mfqyrsidq1P9d p7VRWeAeAeAie3Qbha3EVcoKi8NLCbCPu6NKEEcGlWhSNbYhDM1/IH69lvVc20SFR9Cj BrAMdFhcKqwK8SMXe9iFbssBnB8bYyGLq24NQYxxKoIxK4Q4KBs3uVL6VF+7opeWLVgC aI3Qngb4e1KseUOBdCdRgr+JQoQAypGqDjiTmNgsprEtfAoXYGdqFlqanRX8rPa5003x c+8g== X-Gm-Message-State: ALoCoQkmBzq6gKH1PKhjNZdIvtTZWTZbYzdp8kRelq+/2wxrgNL8lq1QsBFAazj61J5/V6TonjkND1w5lSN0c7Zi2Z4NwhbBMA== X-Received: by 10.107.137.67 with SMTP id l64mr78987170iod.102.1451930685341; Mon, 04 Jan 2016 10:04:45 -0800 (PST) Received: from localhost ([66.64.121.229]) by smtp.gmail.com with ESMTPSA id h19sm11280394igq.6.2016.01.04.10.04.44 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Mon, 04 Jan 2016 10:04:44 -0800 (PST) From: Seth Forshee To: "Eric W. Biederman" , Miklos Szeredi Cc: Alexander Viro , Serge Hallyn , Richard Weinberger , Austin S Hemmelgarn , linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, Seth Forshee Subject: [PATCH RESEND v2 16/18] fuse: Support fuse filesystems outside of init_user_ns Date: Mon, 4 Jan 2016 12:03:55 -0600 Message-Id: <1451930639-94331-17-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1451930639-94331-1-git-send-email-seth.forshee@canonical.com> References: <1451930639-94331-1-git-send-email-seth.forshee@canonical.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP In order to support mounts from namespaces other than init_user_ns, fuse must translate uids and gids to/from the userns of the process servicing requests on /dev/fuse. This patch does that, with a couple of restrictions on the namespace: - The userns for the fuse connection is fixed to the namespace from which /dev/fuse is opened. - The namespace must be the same as s_user_ns. These restrictions simplify the implementation by avoiding the need to pass around userns references and by allowing fuse to rely on the checks in inode_change_ok for ownership changes. Either restriction could be relaxed in the future if needed. For cuse the namespace used for the connection is also simply current_user_ns() at the time /dev/cuse is opened. Signed-off-by: Seth Forshee --- fs/fuse/cuse.c | 3 ++- fs/fuse/dev.c | 13 ++++++++----- fs/fuse/dir.c | 14 +++++++------- fs/fuse/fuse_i.h | 6 +++++- fs/fuse/inode.c | 35 +++++++++++++++++++++++------------ 5 files changed, 45 insertions(+), 26 deletions(-) diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index eae2c11268bc..a10aca57bfe4 100644 --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -48,6 +48,7 @@ #include #include #include +#include #include "fuse_i.h" @@ -498,7 +499,7 @@ static int cuse_channel_open(struct inode *inode, struct file *file) if (!cc) return -ENOMEM; - fuse_conn_init(&cc->fc); + fuse_conn_init(&cc->fc, current_user_ns()); fud = fuse_dev_alloc(&cc->fc); if (!fud) { diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index a4f6f30d6d86..11b4cb0a0e2f 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -127,8 +127,8 @@ static void __fuse_put_request(struct fuse_req *req) static void fuse_req_init_context(struct fuse_conn *fc, struct fuse_req *req) { - req->in.h.uid = from_kuid_munged(&init_user_ns, current_fsuid()); - req->in.h.gid = from_kgid_munged(&init_user_ns, current_fsgid()); + req->in.h.uid = from_kuid(fc->user_ns, current_fsuid()); + req->in.h.gid = from_kgid(fc->user_ns, current_fsgid()); req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns); } @@ -186,7 +186,8 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages, __set_bit(FR_WAITING, &req->flags); if (for_background) __set_bit(FR_BACKGROUND, &req->flags); - if (req->in.h.pid == 0) { + if (req->in.h.pid == 0 || req->in.h.uid == (uid_t)-1 || + req->in.h.gid == (gid_t)-1) { fuse_put_request(fc, req); return ERR_PTR(-EOVERFLOW); } @@ -1248,7 +1249,8 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file, struct fuse_in *in; unsigned reqsize; - if (task_active_pid_ns(current) != fc->pid_ns) + if (task_active_pid_ns(current) != fc->pid_ns || + current_user_ns() != fc->user_ns) return -EIO; restart: @@ -1880,7 +1882,8 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud, struct fuse_req *req; struct fuse_out_header oh; - if (task_active_pid_ns(current) != fc->pid_ns) + if (task_active_pid_ns(current) != fc->pid_ns || + current_user_ns() != fc->user_ns) return -EIO; if (nbytes < sizeof(struct fuse_out_header)) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 5e2e08712d3b..8fd9fe4dcd43 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -841,8 +841,8 @@ static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr, stat->ino = attr->ino; stat->mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777); stat->nlink = attr->nlink; - stat->uid = make_kuid(&init_user_ns, attr->uid); - stat->gid = make_kgid(&init_user_ns, attr->gid); + stat->uid = inode->i_uid; + stat->gid = inode->i_gid; stat->rdev = inode->i_rdev; stat->atime.tv_sec = attr->atime; stat->atime.tv_nsec = attr->atimensec; @@ -1455,17 +1455,17 @@ static bool update_mtime(unsigned ivalid, bool trust_local_mtime) return true; } -static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg, - bool trust_local_cmtime) +static void iattr_to_fattr(struct fuse_conn *fc, struct iattr *iattr, + struct fuse_setattr_in *arg, bool trust_local_cmtime) { unsigned ivalid = iattr->ia_valid; if (ivalid & ATTR_MODE) arg->valid |= FATTR_MODE, arg->mode = iattr->ia_mode; if (ivalid & ATTR_UID) - arg->valid |= FATTR_UID, arg->uid = from_kuid(&init_user_ns, iattr->ia_uid); + arg->valid |= FATTR_UID, arg->uid = from_kuid(fc->user_ns, iattr->ia_uid); if (ivalid & ATTR_GID) - arg->valid |= FATTR_GID, arg->gid = from_kgid(&init_user_ns, iattr->ia_gid); + arg->valid |= FATTR_GID, arg->gid = from_kgid(fc->user_ns, iattr->ia_gid); if (ivalid & ATTR_SIZE) arg->valid |= FATTR_SIZE, arg->size = iattr->ia_size; if (ivalid & ATTR_ATIME) { @@ -1625,7 +1625,7 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr, memset(&inarg, 0, sizeof(inarg)); memset(&outarg, 0, sizeof(outarg)); - iattr_to_fattr(attr, &inarg, trust_local_cmtime); + iattr_to_fattr(fc, attr, &inarg, trust_local_cmtime); if (file) { struct fuse_file *ff = file->private_data; inarg.valid |= FATTR_FH; diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 143b595197b6..5897805405ba 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -23,6 +23,7 @@ #include #include #include +#include /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 @@ -460,6 +461,9 @@ struct fuse_conn { /** The pid namespace for this mount */ struct pid_namespace *pid_ns; + /** The user namespace for this mount */ + struct user_namespace *user_ns; + /** The fuse mount flags for this mount */ unsigned flags; @@ -855,7 +859,7 @@ struct fuse_conn *fuse_conn_get(struct fuse_conn *fc); /** * Initialize fuse_conn */ -void fuse_conn_init(struct fuse_conn *fc); +void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns); /** * Release reference to fuse_conn diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 2f31874ea9db..b7bdfdac3521 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -167,8 +167,8 @@ void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr, inode->i_ino = fuse_squash_ino(attr->ino); inode->i_mode = (inode->i_mode & S_IFMT) | (attr->mode & 07777); set_nlink(inode, attr->nlink); - inode->i_uid = make_kuid(&init_user_ns, attr->uid); - inode->i_gid = make_kgid(&init_user_ns, attr->gid); + inode->i_uid = make_kuid(fc->user_ns, attr->uid); + inode->i_gid = make_kgid(fc->user_ns, attr->gid); inode->i_blocks = attr->blocks; inode->i_atime.tv_sec = attr->atime; inode->i_atime.tv_nsec = attr->atimensec; @@ -467,12 +467,15 @@ static int fuse_match_uint(substring_t *s, unsigned int *res) return err; } -static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev) +static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev, + struct user_namespace *user_ns) { char *p; memset(d, 0, sizeof(struct fuse_mount_data)); d->max_read = ~0; d->blksize = FUSE_DEFAULT_BLKSIZE; + d->user_id = make_kuid(user_ns, 0); + d->group_id = make_kgid(user_ns, 0); while ((p = strsep(&opt, ",")) != NULL) { int token; @@ -503,7 +506,7 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev) case OPT_USER_ID: if (fuse_match_uint(&args[0], &uv)) return 0; - d->user_id = make_kuid(current_user_ns(), uv); + d->user_id = make_kuid(user_ns, uv); if (!uid_valid(d->user_id)) return 0; d->user_id_present = 1; @@ -512,7 +515,7 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev) case OPT_GROUP_ID: if (fuse_match_uint(&args[0], &uv)) return 0; - d->group_id = make_kgid(current_user_ns(), uv); + d->group_id = make_kgid(user_ns, uv); if (!gid_valid(d->group_id)) return 0; d->group_id_present = 1; @@ -555,8 +558,10 @@ static int fuse_show_options(struct seq_file *m, struct dentry *root) struct super_block *sb = root->d_sb; struct fuse_conn *fc = get_fuse_conn_super(sb); - seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id)); - seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id)); + seq_printf(m, ",user_id=%u", + from_kuid_munged(fc->user_ns, fc->user_id)); + seq_printf(m, ",group_id=%u", + from_kgid_munged(fc->user_ns, fc->group_id)); if (fc->flags & FUSE_DEFAULT_PERMISSIONS) seq_puts(m, ",default_permissions"); if (fc->flags & FUSE_ALLOW_OTHER) @@ -587,7 +592,7 @@ static void fuse_pqueue_init(struct fuse_pqueue *fpq) fpq->connected = 1; } -void fuse_conn_init(struct fuse_conn *fc) +void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns) { memset(fc, 0, sizeof(*fc)); spin_lock_init(&fc->lock); @@ -611,6 +616,7 @@ void fuse_conn_init(struct fuse_conn *fc) fc->attr_version = 1; get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key)); fc->pid_ns = get_pid_ns(task_active_pid_ns(current)); + fc->user_ns = get_user_ns(user_ns); } EXPORT_SYMBOL_GPL(fuse_conn_init); @@ -620,6 +626,7 @@ void fuse_conn_put(struct fuse_conn *fc) if (fc->destroy_req) fuse_request_free(fc->destroy_req); put_pid_ns(fc->pid_ns); + put_user_ns(fc->user_ns); fc->release(fc); } } @@ -1046,7 +1053,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) sb->s_flags &= ~(MS_NOSEC | MS_I_VERSION); - if (!parse_fuse_opt(data, &d, is_bdev)) + if (!parse_fuse_opt(data, &d, is_bdev, sb->s_user_ns)) goto err; if (is_bdev) { @@ -1070,8 +1077,12 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) if (!file) goto err; - if ((file->f_op != &fuse_dev_operations) || - (file->f_cred->user_ns != &init_user_ns)) + /* + * Require mount to happen from the same user namespace which + * opened /dev/fuse to prevent potential attacks. + */ + if (file->f_op != &fuse_dev_operations || + file->f_cred->user_ns != sb->s_user_ns) goto err_fput; fc = kmalloc(sizeof(*fc), GFP_KERNEL); @@ -1079,7 +1090,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent) if (!fc) goto err_fput; - fuse_conn_init(fc); + fuse_conn_init(fc, sb->s_user_ns); fc->release = fuse_free_conn; fud = fuse_dev_alloc(fc);