UBUNTU: SAUCE: (namespace) fuse: Support fuse filesystems outside of init_user_ns

[mirror_ubuntu-zesty-kernel.git] / fs / fuse / inode.c

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 5b97ad598dc5898c9b486d161823b334c154dc32..29a8fbeef986def43a5c8284666c19cd8fa15785 100644 (file)
--- 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;
@@ -484,7 +484,8 @@ 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));
@@ -520,7 +521,7 @@ 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;
@@ -529,7 +530,7 @@ 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;
@@ -572,8 +573,8 @@ 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->default_permissions)
                seq_puts(m, ",default_permissions");
        if (fc->allow_other)
@@ -604,7 +605,7 @@ 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);
@@ -628,6 +629,7 @@ 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);
 
@@ -637,6 +639,7 @@ 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);
        }
 }
@@ -1069,7 +1072,7 @@ 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) {
@@ -1094,8 +1097,12 @@ 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);
@@ -1103,7 +1110,7 @@ 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);