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authorLinus Torvalds <torvalds@linux-foundation.org>2018-06-07 18:50:57 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-07 18:50:57 +0300
commitda315f6e03988a7127680bbc26e1028991b899b8 (patch)
treefc4a41dbb22ac0a7a2f683dc5c5c6789957ce5e8 /fs/fuse/inode.c
parent1c8c5a9d38f607c0b6fd12c91cbe1a4418762a21 (diff)
parent543b8f8662fe6d21f19958b666ab0051af9db21a (diff)
downloadlinux-da315f6e03988a7127680bbc26e1028991b899b8.tar.xz
Merge tag 'fuse-update-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
Pull fuse updates from Miklos Szeredi: "The most interesting part of this update is user namespace support, mostly done by Eric Biederman. This enables safe unprivileged fuse mounts within a user namespace. There are also a couple of fixes for bugs found by syzbot and miscellaneous fixes and cleanups" * tag 'fuse-update-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: fuse: don't keep dead fuse_conn at fuse_fill_super(). fuse: fix control dir setup and teardown fuse: fix congested state leak on aborted connections fuse: Allow fully unprivileged mounts fuse: Ensure posix acls are translated outside of init_user_ns fuse: add writeback documentation fuse: honor AT_STATX_FORCE_SYNC fuse: honor AT_STATX_DONT_SYNC fuse: Restrict allow_other to the superblock's namespace or a descendant fuse: Support fuse filesystems outside of init_user_ns fuse: Fail all requests with invalid uids or gids fuse: Remove the buggy retranslation of pids in fuse_dev_do_read fuse: return -ECONNABORTED on /dev/fuse read after abort fuse: atomic_o_trunc should truncate pagecache
Diffstat (limited to 'fs/fuse/inode.c')
-rw-r--r--fs/fuse/inode.c50
1 files changed, 34 insertions, 16 deletions
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index ef309958e060..ffcaf98044b9 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;
@@ -371,7 +371,7 @@ void fuse_unlock_inode(struct inode *inode)
static void fuse_umount_begin(struct super_block *sb)
{
- fuse_abort_conn(get_fuse_conn_super(sb));
+ fuse_abort_conn(get_fuse_conn_super(sb), false);
}
static void fuse_send_destroy(struct fuse_conn *fc)
@@ -393,7 +393,7 @@ static void fuse_put_super(struct super_block *sb)
fuse_send_destroy(fc);
- fuse_abort_conn(fc);
+ fuse_abort_conn(fc, false);
mutex_lock(&fuse_mutex);
list_del(&fc->entry);
fuse_ctl_remove_conn(fc);
@@ -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)
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;
@@ -565,8 +566,8 @@ 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)
@@ -597,7 +598,7 @@ 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);
@@ -621,6 +622,7 @@ 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);
@@ -630,6 +632,7 @@ 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);
}
}
@@ -918,6 +921,8 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
fc->posix_acl = 1;
fc->sb->s_xattr = fuse_acl_xattr_handlers;
}
+ if (arg->flags & FUSE_ABORT_ERROR)
+ fc->abort_err = 1;
} else {
ra_pages = fc->max_read / PAGE_SIZE;
fc->no_lock = 1;
@@ -948,7 +953,8 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
FUSE_FLOCK_LOCKS | FUSE_HAS_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |
- FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL;
+ FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
+ FUSE_ABORT_ERROR;
req->in.h.opcode = FUSE_INIT;
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);
@@ -1061,7 +1067,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
sb->s_flags &= ~(SB_NOSEC | SB_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) {
@@ -1089,16 +1095,27 @@ 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;
+ /*
+ * If we are not in the initial user namespace posix
+ * acls must be translated.
+ */
+ if (sb->s_user_ns != &init_user_ns)
+ sb->s_xattr = fuse_no_acl_xattr_handlers;
+
fc = kmalloc(sizeof(*fc), GFP_KERNEL);
err = -ENOMEM;
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);
@@ -1179,6 +1196,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
fuse_dev_free(fud);
err_put_conn:
fuse_conn_put(fc);
+ sb->s_fs_info = NULL;
err_fput:
fput(file);
err:
@@ -1208,7 +1226,7 @@ static void fuse_kill_sb_anon(struct super_block *sb)
static struct file_system_type fuse_fs_type = {
.owner = THIS_MODULE,
.name = "fuse",
- .fs_flags = FS_HAS_SUBTYPE,
+ .fs_flags = FS_HAS_SUBTYPE | FS_USERNS_MOUNT,
.mount = fuse_mount,
.kill_sb = fuse_kill_sb_anon,
};