From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seth Forshee Subject: [PATCH v4 19/21] fuse: Support fuse filesystems outside of init_user_ns Date: Tue, 26 Apr 2016 14:36:32 -0500 Message-ID: <1461699396-33000-20-git-send-email-seth.forshee@canonical.com> References: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1461699396-33000-1-git-send-email-seth.forshee-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: fuse-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: "Eric W. Biederman" , Miklos Szeredi Cc: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Serge Hallyn , Seth Forshee , dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, Miklos Szeredi , linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-raid-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, fuse-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Austin S Hemmelgarn , linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Alexander Viro , selinux-+05T5uksL2qpZYMLLGbcSA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Pavel Tikhomirov List-Id: linux-raid.ids 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 | 33 +++++++++++++++++++++------------ 5 files changed, 43 insertions(+), 26 deletions(-) diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index c5b6b7165489..98ebd0f4fd4c 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 4e91b2ac25a7..8fa1ce934df3 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 4b855b65d457..ecba75bf6640 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 = make_kuid(fc->user_ns, attr->uid); + stat->gid = make_kgid(fc->user_ns, attr->gid); stat->rdev = inode->i_rdev; stat->atime.tv_sec = attr->atime; stat->atime.tv_nsec = attr->atimensec; @@ -1459,17 +1459,17 @@ 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) { @@ -1629,7 +1629,7 @@ 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 9145445a759a..9f4c3c82edd6 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -24,6 +24,7 @@ #include #include #include +#include /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 @@ -469,6 +470,9 @@ 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; @@ -867,7 +871,7 @@ 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 eade0bfa4488..0a771145d853 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; @@ -467,7 +467,8 @@ 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)); @@ -503,7 +504,7 @@ 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 +513,7 @@ 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 +556,10 @@ 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 +590,7 @@ 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 +614,7 @@ 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 +624,7 @@ 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 +1051,7 @@ 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 +1075,12 @@ 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 +1088,7 @@ 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); -- 2.7.4 ------------------------------------------------------------------------------ Find and fix application performance issues faster with Applications Manager Applications Manager provides deep performance insights into multiple tiers of your business applications. It resolves application problems quickly and reduces your MTTR. Get your free trial! https://ad.doubleclick.net/ddm/clk/302982198;130105516;z -- fuse-devel mailing list To unsubscribe or subscribe, visit https://lists.sourceforge.net/lists/listinfo/fuse-devel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753212AbcDZTir (ORCPT ); Tue, 26 Apr 2016 15:38:47 -0400 Received: from mail-io0-f171.google.com ([209.85.223.171]:34497 "EHLO mail-io0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752983AbcDZThQ (ORCPT ); Tue, 26 Apr 2016 15:37:16 -0400 From: Seth Forshee To: "Eric W. Biederman" , Miklos Szeredi Cc: Alexander Viro , Serge Hallyn , Richard Weinberger , Austin S Hemmelgarn , Miklos Szeredi , Pavel Tikhomirov , 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, cgroups@vger.kernel.org, Seth Forshee Subject: [PATCH v4 19/21] fuse: Support fuse filesystems outside of init_user_ns Date: Tue, 26 Apr 2016 14:36:32 -0500 Message-Id: <1461699396-33000-20-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> References: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 33 +++++++++++++++++++++------------ 5 files changed, 43 insertions(+), 26 deletions(-) diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index c5b6b7165489..98ebd0f4fd4c 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 4e91b2ac25a7..8fa1ce934df3 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 4b855b65d457..ecba75bf6640 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 = make_kuid(fc->user_ns, attr->uid); + stat->gid = make_kgid(fc->user_ns, attr->gid); stat->rdev = inode->i_rdev; stat->atime.tv_sec = attr->atime; stat->atime.tv_nsec = attr->atimensec; @@ -1459,17 +1459,17 @@ 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) { @@ -1629,7 +1629,7 @@ 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 9145445a759a..9f4c3c82edd6 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -24,6 +24,7 @@ #include #include #include +#include /** Max number of pages that can be used in a single read request */ #define FUSE_MAX_PAGES_PER_REQ 32 @@ -469,6 +470,9 @@ 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; @@ -867,7 +871,7 @@ 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 eade0bfa4488..0a771145d853 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; @@ -467,7 +467,8 @@ 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)); @@ -503,7 +504,7 @@ 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 +513,7 @@ 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 +556,10 @@ 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 +590,7 @@ 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 +614,7 @@ 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 +624,7 @@ 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 +1051,7 @@ 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 +1075,12 @@ 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 +1088,7 @@ 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); -- 2.7.4