6 files changed, 43 insertions, 27 deletions

diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index ec85765502f1..5a48cee6d7d3 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -34,7 +34,7 @@ struct posix_acl *fuse_get_acl(struct inode *inode, int type)
                 return ERR_PTR(-ENOMEM);
         size = fuse_getxattr(inode, name, value, PAGE_SIZE);
         if (size > 0)
-                acl = posix_acl_from_xattr(&init_user_ns, value, size);
+                acl = posix_acl_from_xattr(fc->user_ns, value, size);
         else if ((size == 0) || (size == -ENODATA) ||
                  (size == -EOPNOTSUPP && fc->no_getxattr))
                 acl = NULL;
@@ -81,7 +81,7 @@ int fuse_set_acl(struct inode *inode, struct posix_acl *acl, int type)
                 if (!value)
                         return -ENOMEM;
 
-                ret = posix_acl_to_xattr(&init_user_ns, acl, value, size);
+                ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
                 if (ret < 0) {
                         kfree(value);
                         return ret;
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index 31d33b69957f..8f68181256c0 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -48,6 +48,7 @@
 #include <linux/stat.h>
 #include <linux/module.h>
 #include <linux/uio.h>
+#include <linux/user_namespace.h>
 
 #include "fuse_i.h"
 
@@ -498,7 +499,11 @@ static int cuse_channel_open(struct inode *inode, struct file *file)
         if (!cc)
                 return -ENOMEM;
 
-        fuse_conn_init(&cc->fc);
+        /*
+         * Limit the cuse channel to requests that can
+         * be represented in file->f_cred->user_ns.
+         */
+        fuse_conn_init(&cc->fc, file->f_cred->user_ns);
 
         fud = fuse_dev_alloc(&cc->fc);
         if (!fud) {
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 4852f8803156..686631f12001 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -156,8 +156,8 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
                 goto out;
         }
 
-        req->in.h.uid = from_kuid(&init_user_ns, current_fsuid());
-        req->in.h.gid = from_kgid(&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);
 
         __set_bit(FR_WAITING, &req->flags);
@@ -257,8 +257,8 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
         if (!req)
                 req = get_reserved_req(fc, file);
 
-        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_munged(fc->user_ns, current_fsuid());
+        req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
         req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
 
         __set_bit(FR_WAITING, &req->flags);
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 7a980b4462d9..cf8a1cd7a62e 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -858,8 +858,8 @@ 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;
@@ -1475,17 +1475,17 @@ 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) {
@@ -1657,7 +1657,7 @@ int fuse_do_setattr(struct dentry *dentry, 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 7d2e7deea64b..f630951df8dc 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -26,6 +26,7 @@
 #include <linux/xattr.h>
 #include <linux/pid_namespace.h>
 #include <linux/refcount.h>
+#include <linux/user_namespace.h>
 
 /** Max number of pages that can be used in a single read request */
 #define FUSE_MAX_PAGES_PER_REQ 32
@@ -466,6 +467,9 @@ 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;
+
         /** Maximum read size */
         unsigned max_read;
 
@@ -876,7 +880,7 @@ 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 3c9b675d99da..1643043d4fe5 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -171,8 +171,8 @@ 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;
@@ -477,7 +477,8 @@ 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));
@@ -513,7 +514,7 @@ 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;
@@ -522,7 +523,7 @@ static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)