[PATCH v1 1/3] fs/fuse: introduce and use fuse_simple_idmap_request() helper

[PATCH v1 1/3] fs/fuse: introduce and use fuse_simple_idmap_request() helper

[Alexander Mikhalitsyn]

Let's convert all existing callers properly.

No functional changes intended.

Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
---
 fs/fuse/dax.c     |  4 ++--
 fs/fuse/dev.c     |  6 +++---
 fs/fuse/dir.c     | 26 +++++++++++++-------------
 fs/fuse/file.c    | 32 ++++++++++++++++----------------
 fs/fuse/fuse_i.h  | 18 ++++++++++++++++--
 fs/fuse/inode.c   |  6 +++---
 fs/fuse/ioctl.c   |  2 +-
 fs/fuse/readdir.c |  4 ++--
 fs/fuse/xattr.c   |  8 ++++----
 9 files changed, 60 insertions(+), 46 deletions(-)

diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 6d8368d66dd4..12ef91d170bb 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -207,7 +207,7 @@ static int fuse_setup_one_mapping(struct inode *inode, unsigned long start_idx,
 	args.in_numargs = 1;
 	args.in_args[0].size = sizeof(inarg);
 	args.in_args[0].value = &inarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err < 0)
 		return err;
 	dmap->writable = writable;
@@ -245,7 +245,7 @@ static int fuse_send_removemapping(struct inode *inode,
 	args.in_args[0].value = inargp;
 	args.in_args[1].size = inargp->count * sizeof(*remove_one);
 	args.in_args[1].value = remove_one;
-	return fuse_simple_request(NULL, fm, &args);
+	return fuse_simple_request(fm, &args);
 }
 
 static int dmap_removemapping_list(struct inode *inode, unsigned int num,
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5ca2ab48527e..04a6490a587c 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -539,9 +539,9 @@ static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
 		__set_bit(FR_ASYNC, &req->flags);
 }
 
-ssize_t fuse_simple_request(struct mnt_idmap *idmap,
-			    struct fuse_mount *fm,
-			    struct fuse_args *args)
+ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
+			      struct fuse_mount *fm,
+			      struct fuse_args *args)
 {
 	struct fuse_conn *fc = fm->fc;
 	struct fuse_req *req;
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 99f9948bf68b..491e112819be 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -230,7 +230,7 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 		parent = dget_parent(entry);
 		fuse_lookup_init(fm->fc, &args, get_node_id(d_inode(parent)),
 				 &entry->d_name, &outarg);
-		ret = fuse_simple_request(NULL, fm, &args);
+		ret = fuse_simple_request(fm, &args);
 		dput(parent);
 		/* Zero nodeid is same as -ENOENT */
 		if (!ret && !outarg.nodeid)
@@ -383,7 +383,7 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name
 	attr_version = fuse_get_attr_version(fm->fc);
 
 	fuse_lookup_init(fm->fc, &args, nodeid, name, outarg);
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	/* Zero nodeid is same as -ENOENT, but with valid timeout */
 	if (err || !outarg->nodeid)
 		goto out_put_forget;
@@ -677,7 +677,7 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
 	if (err)
 		goto out_free_ff;
 
-	err = fuse_simple_request(idmap, fm, &args);
+	err = fuse_simple_idmap_request(idmap, fm, &args);
 	free_ext_value(&args);
 	if (err)
 		goto out_free_ff;
@@ -809,7 +809,7 @@ static int create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
 			goto out_put_forget_req;
 	}
 
-	err = fuse_simple_request(idmap, fm, args);
+	err = fuse_simple_idmap_request(idmap, fm, args);
 	free_ext_value(args);
 	if (err)
 		goto out_put_forget_req;
@@ -994,7 +994,7 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 	args.in_numargs = 1;
 	args.in_args[0].size = entry->d_name.len + 1;
 	args.in_args[0].value = entry->d_name.name;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (!err) {
 		fuse_dir_changed(dir);
 		fuse_entry_unlinked(entry);
@@ -1017,7 +1017,7 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
 	args.in_numargs = 1;
 	args.in_args[0].size = entry->d_name.len + 1;
 	args.in_args[0].value = entry->d_name.name;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (!err) {
 		fuse_dir_changed(dir);
 		fuse_entry_unlinked(entry);
@@ -1047,7 +1047,7 @@ static int fuse_rename_common(struct mnt_idmap *idmap, struct inode *olddir, str
 	args.in_args[1].value = oldent->d_name.name;
 	args.in_args[2].size = newent->d_name.len + 1;
 	args.in_args[2].value = newent->d_name.name;
-	err = fuse_simple_request(idmap, fm, &args);
+	err = fuse_simple_idmap_request(idmap, fm, &args);
 	if (!err) {
 		/* ctime changes */
 		fuse_update_ctime(d_inode(oldent));
@@ -1222,7 +1222,7 @@ static int fuse_do_statx(struct mnt_idmap *idmap, struct inode *inode,
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err)
 		return err;
 
@@ -1280,7 +1280,7 @@ static int fuse_do_getattr(struct mnt_idmap *idmap, struct inode *inode,
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (!err) {
 		if (fuse_invalid_attr(&outarg.attr) ||
 		    inode_wrong_type(inode, outarg.attr.mode)) {
@@ -1492,7 +1492,7 @@ static int fuse_access(struct inode *inode, int mask)
 	args.in_numargs = 1;
 	args.in_args[0].size = sizeof(inarg);
 	args.in_args[0].value = &inarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fm->fc->no_access = 1;
 		err = 0;
@@ -1604,7 +1604,7 @@ static int fuse_readlink_page(struct inode *inode, struct page *page)
 	ap.args.page_zeroing = true;
 	ap.args.out_numargs = 1;
 	ap.args.out_args[0].size = desc.length;
-	res = fuse_simple_request(NULL, fm, &ap.args);
+	res = fuse_simple_request(fm, &ap.args);
 
 	fuse_invalidate_atime(inode);
 
@@ -1889,7 +1889,7 @@ int fuse_flush_times(struct inode *inode, struct fuse_file *ff)
 	}
 	fuse_setattr_fill(fm->fc, &args, inode, &inarg, &outarg);
 
-	return fuse_simple_request(NULL, fm, &args);
+	return fuse_simple_request(fm, &args);
 }
 
 /*
@@ -2002,7 +2002,7 @@ int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 			inarg.valid |= FATTR_KILL_SUIDGID;
 	}
 	fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err) {
 		if (err == -EINTR)
 			fuse_invalidate_attr(inode);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index ca553d7a7c9e..b8afeca12487 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -48,7 +48,7 @@ static int fuse_send_open(struct fuse_mount *fm, u64 nodeid,
 	args.out_args[0].size = sizeof(*outargp);
 	args.out_args[0].value = outargp;
 
-	return fuse_simple_request(NULL, fm, &args);
+	return fuse_simple_request(fm, &args);
 }
 
 struct fuse_file *fuse_file_alloc(struct fuse_mount *fm, bool release)
@@ -111,7 +111,7 @@ static void fuse_file_put(struct fuse_file *ff, bool sync)
 		if (!args) {
 			/* Do nothing when server does not implement 'open' */
 		} else if (sync) {
-			fuse_simple_request(NULL, ff->fm, args);
+			fuse_simple_request(ff->fm, args);
 			fuse_release_end(ff->fm, args, 0);
 		} else {
 			args->end = fuse_release_end;
@@ -539,7 +539,7 @@ static int fuse_flush(struct file *file, fl_owner_t id)
 	args.in_args[0].value = &inarg;
 	args.force = true;
 
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fm->fc->no_flush = 1;
 		err = 0;
@@ -572,7 +572,7 @@ int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
 	args.in_numargs = 1;
 	args.in_args[0].size = sizeof(inarg);
 	args.in_args[0].value = &inarg;
-	return fuse_simple_request(NULL, fm, &args);
+	return fuse_simple_request(fm, &args);
 }
 
 static int fuse_fsync(struct file *file, loff_t start, loff_t end,
@@ -814,7 +814,7 @@ static ssize_t fuse_send_read(struct fuse_io_args *ia, loff_t pos, size_t count,
 	if (ia->io->async)
 		return fuse_async_req_send(fm, ia, count);
 
-	return fuse_simple_request(NULL, fm, &ia->ap.args);
+	return fuse_simple_request(fm, &ia->ap.args);
 }
 
 static void fuse_read_update_size(struct inode *inode, loff_t size,
@@ -878,7 +878,7 @@ static int fuse_do_readpage(struct file *file, struct page *page)
 		desc.length--;
 
 	fuse_read_args_fill(&ia, file, pos, desc.length, FUSE_READ);
-	res = fuse_simple_request(NULL, fm, &ia.ap.args);
+	res = fuse_simple_request(fm, &ia.ap.args);
 	if (res < 0)
 		return res;
 	/*
@@ -976,7 +976,7 @@ static void fuse_send_readpages(struct fuse_io_args *ia, struct file *file)
 		if (!err)
 			return;
 	} else {
-		res = fuse_simple_request(NULL, fm, &ap->args);
+		res = fuse_simple_request(fm, &ap->args);
 		err = res < 0 ? res : 0;
 	}
 	fuse_readpages_end(fm, &ap->args, err);
@@ -1101,7 +1101,7 @@ static ssize_t fuse_send_write(struct fuse_io_args *ia, loff_t pos,
 	if (ia->io->async)
 		return fuse_async_req_send(fm, ia, count);
 
-	err = fuse_simple_request(NULL, fm, &ia->ap.args);
+	err = fuse_simple_request(fm, &ia->ap.args);
 	if (!err && ia->write.out.size > count)
 		err = -EIO;
 
@@ -1147,7 +1147,7 @@ static ssize_t fuse_send_write_pages(struct fuse_io_args *ia,
 	if (fm->fc->handle_killpriv_v2 && !capable(CAP_FSETID))
 		ia->write.in.write_flags |= FUSE_WRITE_KILL_SUIDGID;
 
-	err = fuse_simple_request(NULL, fm, &ap->args);
+	err = fuse_simple_request(fm, &ap->args);
 	if (!err && ia->write.out.size > count)
 		err = -EIO;
 
@@ -2662,7 +2662,7 @@ static int fuse_getlk(struct file *file, struct file_lock *fl)
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (!err)
 		err = convert_fuse_file_lock(fm->fc, &outarg.lk, fl);
 
@@ -2686,7 +2686,7 @@ static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
 	}
 
 	fuse_lk_fill(&args, file, fl, opcode, pid_nr, flock, &inarg);
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 
 	/* locking is restartable */
 	if (err == -EINTR)
@@ -2760,7 +2760,7 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS)
 		fm->fc->no_bmap = 1;
 
@@ -2792,7 +2792,7 @@ static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err) {
 		if (err == -ENOSYS) {
 			fm->fc->no_lseek = 1;
@@ -2925,7 +2925,7 @@ __poll_t fuse_file_poll(struct file *file, poll_table *wait)
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 
 	if (!err)
 		return demangle_poll(outarg.revents);
@@ -3147,7 +3147,7 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
 	args.in_numargs = 1;
 	args.in_args[0].size = sizeof(inarg);
 	args.in_args[0].value = &inarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fm->fc->no_fallocate = 1;
 		err = -EOPNOTSUPP;
@@ -3259,7 +3259,7 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fc->no_copy_file_range = 1;
 		err = -EOPNOTSUPP;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 7dd0661aeab6..b2c7834f21b5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1147,8 +1147,22 @@ void __exit fuse_ctl_cleanup(void);
 /**
  * Simple request sending that does request allocation and freeing
  */
-ssize_t fuse_simple_request(struct mnt_idmap *idmap, struct fuse_mount *fm,
-			    struct fuse_args *args);
+ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
+			      struct fuse_mount *fm,
+			      struct fuse_args *args);
+
+static inline ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
+{
+	return __fuse_simple_request(NULL, fm, args);
+}
+
+static inline ssize_t fuse_simple_idmap_request(struct mnt_idmap *idmap,
+						struct fuse_mount *fm,
+						struct fuse_args *args)
+{
+	return __fuse_simple_request(idmap, fm, args);
+}
+
 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
 			   gfp_t gfp_flags);
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index d7edb3fb829f..fd3321e29a3e 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -586,7 +586,7 @@ static void fuse_send_destroy(struct fuse_mount *fm)
 		args.opcode = FUSE_DESTROY;
 		args.force = true;
 		args.nocreds = true;
-		fuse_simple_request(NULL, fm, &args);
+		fuse_simple_request(fm, &args);
 	}
 }
 
@@ -624,7 +624,7 @@ static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 	args.out_numargs = 1;
 	args.out_args[0].size = sizeof(outarg);
 	args.out_args[0].value = &outarg;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (!err)
 		convert_fuse_statfs(buf, &outarg.st);
 	return err;
@@ -713,7 +713,7 @@ static int fuse_sync_fs(struct super_block *sb, int wait)
 	args.nodeid = get_node_id(sb->s_root->d_inode);
 	args.out_numargs = 0;
 
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fc->sync_fs = 0;
 		err = 0;
diff --git a/fs/fuse/ioctl.c b/fs/fuse/ioctl.c
index b40dd931167d..572ce8a82ceb 100644
--- a/fs/fuse/ioctl.c
+++ b/fs/fuse/ioctl.c
@@ -18,7 +18,7 @@ static ssize_t fuse_send_ioctl(struct fuse_mount *fm, struct fuse_args *args,
 	args->out_args[0].size = sizeof(*outarg);
 	args->out_args[0].value = outarg;
 
-	ret = fuse_simple_request(NULL, fm, args);
+	ret = fuse_simple_request(fm, args);
 
 	/* Translate ENOSYS, which shouldn't be returned from fs */
 	if (ret == -ENOSYS)
diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index e8a093289421..0377b6dc24c8 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -279,7 +279,7 @@ static void fuse_force_forget(struct file *file, u64 nodeid)
 	args.force = true;
 	args.noreply = true;
 
-	fuse_simple_request(NULL, fm, &args);
+	fuse_simple_request(fm, &args);
 	/* ignore errors */
 }
 
@@ -358,7 +358,7 @@ static int fuse_readdir_uncached(struct file *file, struct dir_context *ctx)
 				    FUSE_READDIR);
 	}
 	locked = fuse_lock_inode(inode);
-	res = fuse_simple_request(NULL, fm, &ap->args);
+	res = fuse_simple_request(fm, &ap->args);
 	fuse_unlock_inode(inode, locked);
 	if (res >= 0) {
 		if (!res) {
diff --git a/fs/fuse/xattr.c b/fs/fuse/xattr.c
index 0a9b60de3668..9f568d345c51 100644
--- a/fs/fuse/xattr.c
+++ b/fs/fuse/xattr.c
@@ -37,7 +37,7 @@ int fuse_setxattr(struct inode *inode, const char *name, const void *value,
 	args.in_args[1].value = name;
 	args.in_args[2].size = size;
 	args.in_args[2].value = value;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fm->fc->no_setxattr = 1;
 		err = -EOPNOTSUPP;
@@ -79,7 +79,7 @@ ssize_t fuse_getxattr(struct inode *inode, const char *name, void *value,
 		args.out_args[0].size = sizeof(outarg);
 		args.out_args[0].value = &outarg;
 	}
-	ret = fuse_simple_request(NULL, fm, &args);
+	ret = fuse_simple_request(fm, &args);
 	if (!ret && !size)
 		ret = min_t(size_t, outarg.size, XATTR_SIZE_MAX);
 	if (ret == -ENOSYS) {
@@ -141,7 +141,7 @@ ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
 		args.out_args[0].size = sizeof(outarg);
 		args.out_args[0].value = &outarg;
 	}
-	ret = fuse_simple_request(NULL, fm, &args);
+	ret = fuse_simple_request(fm, &args);
 	if (!ret && !size)
 		ret = min_t(size_t, outarg.size, XATTR_LIST_MAX);
 	if (ret > 0 && size)
@@ -167,7 +167,7 @@ int fuse_removexattr(struct inode *inode, const char *name)
 	args.in_numargs = 1;
 	args.in_args[0].size = strlen(name) + 1;
 	args.in_args[0].value = name;
-	err = fuse_simple_request(NULL, fm, &args);
+	err = fuse_simple_request(fm, &args);
 	if (err == -ENOSYS) {
 		fm->fc->no_removexattr = 1;
 		err = -EOPNOTSUPP;
-- 
2.34.1

[PATCH v1 2/3] fs/mnt_idmapping: introduce an invalid_mnt_idmap

[Alexander Mikhalitsyn]

Link: https://lore.kernel.org/linux-fsdevel/20240904-baugrube-erhoben-b3c1c49a2645@brauner/
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
---
 fs/mnt_idmapping.c            | 22 ++++++++++++++++++++--
 include/linux/mnt_idmapping.h |  1 +
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/fs/mnt_idmapping.c b/fs/mnt_idmapping.c
index 3c60f1eaca61..cbca6500848e 100644
--- a/fs/mnt_idmapping.c
+++ b/fs/mnt_idmapping.c
@@ -32,6 +32,15 @@ struct mnt_idmap nop_mnt_idmap = {
 };
 EXPORT_SYMBOL_GPL(nop_mnt_idmap);
 
+/*
+ * Carries the invalid idmapping of a full 0-4294967295 {g,u}id range.
+ * This means that all {g,u}ids are mapped to INVALID_VFS{G,U}ID.
+ */
+struct mnt_idmap invalid_mnt_idmap = {
+	.count	= REFCOUNT_INIT(1),
+};
+EXPORT_SYMBOL_GPL(invalid_mnt_idmap);
+
 /**
  * initial_idmapping - check whether this is the initial mapping
  * @ns: idmapping to check
@@ -75,6 +84,8 @@ vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
 
 	if (idmap == &nop_mnt_idmap)
 		return VFSUIDT_INIT(kuid);
+	if (idmap == &invalid_mnt_idmap)
+		return INVALID_VFSUID;
 	if (initial_idmapping(fs_userns))
 		uid = __kuid_val(kuid);
 	else
@@ -112,6 +123,8 @@ vfsgid_t make_vfsgid(struct mnt_idmap *idmap,
 
 	if (idmap == &nop_mnt_idmap)
 		return VFSGIDT_INIT(kgid);
+	if (idmap == &invalid_mnt_idmap)
+		return INVALID_VFSGID;
 	if (initial_idmapping(fs_userns))
 		gid = __kgid_val(kgid);
 	else
@@ -140,6 +153,8 @@ kuid_t from_vfsuid(struct mnt_idmap *idmap,
 
 	if (idmap == &nop_mnt_idmap)
 		return AS_KUIDT(vfsuid);
+	if (idmap == &invalid_mnt_idmap)
+		return INVALID_UID;
 	uid = map_id_up(&idmap->uid_map, __vfsuid_val(vfsuid));
 	if (uid == (uid_t)-1)
 		return INVALID_UID;
@@ -167,6 +182,8 @@ kgid_t from_vfsgid(struct mnt_idmap *idmap,
 
 	if (idmap == &nop_mnt_idmap)
 		return AS_KGIDT(vfsgid);
+	if (idmap == &invalid_mnt_idmap)
+		return INVALID_GID;
 	gid = map_id_up(&idmap->gid_map, __vfsgid_val(vfsgid));
 	if (gid == (gid_t)-1)
 		return INVALID_GID;
@@ -296,7 +313,7 @@ struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns)
  */
 struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap)
 {
-	if (idmap != &nop_mnt_idmap)
+	if (idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap)
 		refcount_inc(&idmap->count);
 
 	return idmap;
@@ -312,7 +329,8 @@ EXPORT_SYMBOL_GPL(mnt_idmap_get);
  */
 void mnt_idmap_put(struct mnt_idmap *idmap)
 {
-	if (idmap != &nop_mnt_idmap && refcount_dec_and_test(&idmap->count))
+	if (idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap &&
+	    refcount_dec_and_test(&idmap->count))
 		free_mnt_idmap(idmap);
 }
 EXPORT_SYMBOL_GPL(mnt_idmap_put);
diff --git a/include/linux/mnt_idmapping.h b/include/linux/mnt_idmapping.h
index cd4d5c8781f5..b1b219bc3422 100644
--- a/include/linux/mnt_idmapping.h
+++ b/include/linux/mnt_idmapping.h
@@ -9,6 +9,7 @@ struct mnt_idmap;
 struct user_namespace;
 
 extern struct mnt_idmap nop_mnt_idmap;
+extern struct mnt_idmap invalid_mnt_idmap;
 extern struct user_namespace init_user_ns;
 
 typedef struct {
-- 
2.34.1

[PATCH v1 3/3] fs/fuse: convert to use invalid_mnt_idmap

[Alexander Mikhalitsyn]

We should convert fs/fuse code to use a newly introduced
invalid_mnt_idmap instead of passing a NULL as idmap pointer.

Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
---
 fs/fuse/dev.c    | 47 +++++++++++++++++++++++------------------------
 fs/fuse/dir.c    |  6 +++---
 fs/fuse/fuse_i.h |  2 +-
 3 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 04a6490a587c..e42b2f38d35f 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -114,7 +114,11 @@ static struct fuse_req *fuse_get_req(struct mnt_idmap *idmap,
 {
 	struct fuse_conn *fc = fm->fc;
 	struct fuse_req *req;
+	bool no_idmap = (fm->sb->s_iflags & SB_I_NOIDMAP);
+	kuid_t fsuid;
+	kgid_t fsgid;
 	int err;
+
 	atomic_inc(&fc->num_waiting);
 
 	if (fuse_block_alloc(fc, for_background)) {
@@ -148,29 +152,24 @@ static struct fuse_req *fuse_get_req(struct mnt_idmap *idmap,
 	if (for_background)
 		__set_bit(FR_BACKGROUND, &req->flags);
 
-	if ((fm->sb->s_iflags & SB_I_NOIDMAP) || idmap) {
-		kuid_t idmapped_fsuid;
-		kgid_t idmapped_fsgid;
+	/*
+	 * Keep the old behavior when idmappings support was not
+	 * declared by a FUSE server.
+	 *
+	 * For those FUSE servers who support idmapped mounts,
+	 * we send UID/GID only along with "inode creation"
+	 * fuse requests, otherwise idmap == &invalid_mnt_idmap and
+	 * req->in.h.{u,g}id will be equal to FUSE_INVALID_UIDGID.
+	 */
+	fsuid = no_idmap ? current_fsuid() : mapped_fsuid(idmap, fc->user_ns);
+	fsgid = no_idmap ? current_fsgid() : mapped_fsgid(idmap, fc->user_ns);
+	req->in.h.uid = from_kuid(fc->user_ns, fsuid);
+	req->in.h.gid = from_kgid(fc->user_ns, fsgid);
 
-		/*
-		 * Note, that when
-		 * (fm->sb->s_iflags & SB_I_NOIDMAP) is true, then
-		 * (idmap == &nop_mnt_idmap) is always true and therefore,
-		 * mapped_fsuid(idmap, fc->user_ns) == current_fsuid().
-		 */
-		idmapped_fsuid = idmap ? mapped_fsuid(idmap, fc->user_ns) : current_fsuid();
-		idmapped_fsgid = idmap ? mapped_fsgid(idmap, fc->user_ns) : current_fsgid();
-		req->in.h.uid = from_kuid(fc->user_ns, idmapped_fsuid);
-		req->in.h.gid = from_kgid(fc->user_ns, idmapped_fsgid);
-
-		if (unlikely(req->in.h.uid == ((uid_t)-1) ||
-			     req->in.h.gid == ((gid_t)-1))) {
-			fuse_put_request(req);
-			return ERR_PTR(-EOVERFLOW);
-		}
-	} else {
-		req->in.h.uid = FUSE_INVALID_UIDGID;
-		req->in.h.gid = FUSE_INVALID_UIDGID;
+	if (no_idmap && unlikely(req->in.h.uid == ((uid_t)-1) ||
+				 req->in.h.gid == ((gid_t)-1))) {
+		fuse_put_request(req);
+		return ERR_PTR(-EOVERFLOW);
 	}
 
 	return req;
@@ -619,7 +618,7 @@ int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
 		__set_bit(FR_BACKGROUND, &req->flags);
 	} else {
 		WARN_ON(args->nocreds);
-		req = fuse_get_req(NULL, fm, true);
+		req = fuse_get_req(&invalid_mnt_idmap, fm, true);
 		if (IS_ERR(req))
 			return PTR_ERR(req);
 	}
@@ -641,7 +640,7 @@ static int fuse_simple_notify_reply(struct fuse_mount *fm,
 	struct fuse_req *req;
 	struct fuse_iqueue *fiq = &fm->fc->iq;
 
-	req = fuse_get_req(NULL, fm, false);
+	req = fuse_get_req(&invalid_mnt_idmap, fm, false);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 491e112819be..54104dd48af7 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1093,7 +1093,7 @@ static int fuse_rename2(struct mnt_idmap *idmap, struct inode *olddir,
 		if (fc->no_rename2 || fc->minor < 23)
 			return -EINVAL;
 
-		err = fuse_rename_common((flags & RENAME_WHITEOUT) ? idmap : NULL,
+		err = fuse_rename_common((flags & RENAME_WHITEOUT) ? idmap : &invalid_mnt_idmap,
 					 olddir, oldent, newdir, newent, flags,
 					 FUSE_RENAME2,
 					 sizeof(struct fuse_rename2_in));
@@ -1102,7 +1102,7 @@ static int fuse_rename2(struct mnt_idmap *idmap, struct inode *olddir,
 			err = -EINVAL;
 		}
 	} else {
-		err = fuse_rename_common(NULL, olddir, oldent, newdir, newent, 0,
+		err = fuse_rename_common(&invalid_mnt_idmap, olddir, oldent, newdir, newent, 0,
 					 FUSE_RENAME,
 					 sizeof(struct fuse_rename_in));
 	}
@@ -1127,7 +1127,7 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
 	args.in_args[0].value = &inarg;
 	args.in_args[1].size = newent->d_name.len + 1;
 	args.in_args[1].value = newent->d_name.name;
-	err = create_new_entry(NULL, fm, &args, newdir, newent, inode->i_mode);
+	err = create_new_entry(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
 	if (!err)
 		fuse_update_ctime_in_cache(inode);
 	else if (err == -EINTR)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b2c7834f21b5..e6cc3d552b13 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1153,7 +1153,7 @@ ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
 
 static inline ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
 {
-	return __fuse_simple_request(NULL, fm, args);
+	return __fuse_simple_request(&invalid_mnt_idmap, fm, args);
 }
 
 static inline ssize_t fuse_simple_idmap_request(struct mnt_idmap *idmap,
-- 
2.34.1

Re: [PATCH v1 1/3] fs/fuse: introduce and use fuse_simple_idmap_request() helper

[Christian Brauner]

On Fri, Sep 06, 2024 at 04:34:51PM GMT, Alexander Mikhalitsyn wrote:
> Let's convert all existing callers properly.
> 
> No functional changes intended.
> 
> Suggested-by: Christian Brauner <brauner@kernel.org>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> ---

Reviewed-by: Christian Brauner <brauner@kernel.org>

Re: [PATCH v1 2/3] fs/mnt_idmapping: introduce an invalid_mnt_idmap

[Christian Brauner]

On Fri, Sep 06, 2024 at 04:34:52PM GMT, Alexander Mikhalitsyn wrote:
> Link: https://lore.kernel.org/linux-fsdevel/20240904-baugrube-erhoben-b3c1c49a2645@brauner/
> Suggested-by: Christian Brauner <brauner@kernel.org>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> ---
>  fs/mnt_idmapping.c            | 22 ++++++++++++++++++++--
>  include/linux/mnt_idmapping.h |  1 +
>  2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/mnt_idmapping.c b/fs/mnt_idmapping.c
> index 3c60f1eaca61..cbca6500848e 100644
> --- a/fs/mnt_idmapping.c
> +++ b/fs/mnt_idmapping.c
> @@ -32,6 +32,15 @@ struct mnt_idmap nop_mnt_idmap = {
>  };
>  EXPORT_SYMBOL_GPL(nop_mnt_idmap);
>  
> +/*
> + * Carries the invalid idmapping of a full 0-4294967295 {g,u}id range.
> + * This means that all {g,u}ids are mapped to INVALID_VFS{G,U}ID.
> + */
> +struct mnt_idmap invalid_mnt_idmap = {
> +	.count	= REFCOUNT_INIT(1),
> +};
> +EXPORT_SYMBOL_GPL(invalid_mnt_idmap);
> +
>  /**
>   * initial_idmapping - check whether this is the initial mapping
>   * @ns: idmapping to check
> @@ -75,6 +84,8 @@ vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
>  
>  	if (idmap == &nop_mnt_idmap)
>  		return VFSUIDT_INIT(kuid);
> +	if (idmap == &invalid_mnt_idmap)
> +		return INVALID_VFSUID;

Could possibly deserve an:

if (unlikely(idmap == &invalid_mnt_idmap))
	return INVALID_VFSUID;

and technically I guess we could also do:

if (likely(idmap == &nop_mnt_idmap))
	return VFSUIDT_INIT(kuid);

but not that relevant for this patch.

Re: [PATCH v1 3/3] fs/fuse: convert to use invalid_mnt_idmap

[Christian Brauner]

On Fri, Sep 06, 2024 at 04:34:53PM GMT, Alexander Mikhalitsyn wrote:
> We should convert fs/fuse code to use a newly introduced
> invalid_mnt_idmap instead of passing a NULL as idmap pointer.
> 
> Suggested-by: Christian Brauner <brauner@kernel.org>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> ---

Reviewed-by: Christian Brauner <brauner@kernel.org>

Re: [PATCH v1 2/3] fs/mnt_idmapping: introduce an invalid_mnt_idmap

[Christian Brauner]

On Mon, Sep 09, 2024 at 02:57:51PM GMT, Christian Brauner wrote:
> On Fri, Sep 06, 2024 at 04:34:52PM GMT, Alexander Mikhalitsyn wrote:
> > Link: https://lore.kernel.org/linux-fsdevel/20240904-baugrube-erhoben-b3c1c49a2645@brauner/
> > Suggested-by: Christian Brauner <brauner@kernel.org>
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> > ---
> >  fs/mnt_idmapping.c            | 22 ++++++++++++++++++++--
> >  include/linux/mnt_idmapping.h |  1 +
> >  2 files changed, 21 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/mnt_idmapping.c b/fs/mnt_idmapping.c
> > index 3c60f1eaca61..cbca6500848e 100644
> > --- a/fs/mnt_idmapping.c
> > +++ b/fs/mnt_idmapping.c
> > @@ -32,6 +32,15 @@ struct mnt_idmap nop_mnt_idmap = {
> >  };
> >  EXPORT_SYMBOL_GPL(nop_mnt_idmap);
> >  
> > +/*
> > + * Carries the invalid idmapping of a full 0-4294967295 {g,u}id range.
> > + * This means that all {g,u}ids are mapped to INVALID_VFS{G,U}ID.
> > + */
> > +struct mnt_idmap invalid_mnt_idmap = {
> > +	.count	= REFCOUNT_INIT(1),
> > +};
> > +EXPORT_SYMBOL_GPL(invalid_mnt_idmap);
> > +
> >  /**
> >   * initial_idmapping - check whether this is the initial mapping
> >   * @ns: idmapping to check
> > @@ -75,6 +84,8 @@ vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
> >  
> >  	if (idmap == &nop_mnt_idmap)
> >  		return VFSUIDT_INIT(kuid);
> > +	if (idmap == &invalid_mnt_idmap)
> > +		return INVALID_VFSUID;
> 
> Could possibly deserve an:
> 
> if (unlikely(idmap == &invalid_mnt_idmap))
> 	return INVALID_VFSUID;
> 
> and technically I guess we could also do:
> 
> if (likely(idmap == &nop_mnt_idmap))
> 	return VFSUIDT_INIT(kuid);
> 
> but not that relevant for this patch.

Forgot:

Reviewed-by: Christian Brauner <brauner@kernel.org>

Re: [PATCH v1 2/3] fs/mnt_idmapping: introduce an invalid_mnt_idmap

[Aleksandr Mikhalitsyn]

On Mon, Sep 9, 2024 at 2:57 PM Christian Brauner <brauner@kernel.org> wrote:
>
> On Fri, Sep 06, 2024 at 04:34:52PM GMT, Alexander Mikhalitsyn wrote:
> > Link: https://lore.kernel.org/linux-fsdevel/20240904-baugrube-erhoben-b3c1c49a2645@brauner/
> > Suggested-by: Christian Brauner <brauner@kernel.org>
> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> > ---
> >  fs/mnt_idmapping.c            | 22 ++++++++++++++++++++--
> >  include/linux/mnt_idmapping.h |  1 +
> >  2 files changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/mnt_idmapping.c b/fs/mnt_idmapping.c
> > index 3c60f1eaca61..cbca6500848e 100644
> > --- a/fs/mnt_idmapping.c
> > +++ b/fs/mnt_idmapping.c
> > @@ -32,6 +32,15 @@ struct mnt_idmap nop_mnt_idmap = {
> >  };
> >  EXPORT_SYMBOL_GPL(nop_mnt_idmap);
> >
> > +/*
> > + * Carries the invalid idmapping of a full 0-4294967295 {g,u}id range.
> > + * This means that all {g,u}ids are mapped to INVALID_VFS{G,U}ID.
> > + */
> > +struct mnt_idmap invalid_mnt_idmap = {
> > +     .count  = REFCOUNT_INIT(1),
> > +};
> > +EXPORT_SYMBOL_GPL(invalid_mnt_idmap);
> > +
> >  /**
> >   * initial_idmapping - check whether this is the initial mapping
> >   * @ns: idmapping to check
> > @@ -75,6 +84,8 @@ vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
> >
> >       if (idmap == &nop_mnt_idmap)
> >               return VFSUIDT_INIT(kuid);
> > +     if (idmap == &invalid_mnt_idmap)
> > +             return INVALID_VFSUID;
>
> Could possibly deserve an:
>
> if (unlikely(idmap == &invalid_mnt_idmap))
>         return INVALID_VFSUID;
>
> and technically I guess we could also do:
>
> if (likely(idmap == &nop_mnt_idmap))
>         return VFSUIDT_INIT(kuid);
>
> but not that relevant for this patch.

Yeah, I'm happy to submit that change (if you don't mind) a bit later
when this will be merged,
cause in this case we can add this likely()/unlikely() at once for
both nop_mnt_idmap/invalid_mnt_idmap.

Kind regards,
Alex

Re: [PATCH v1 2/3] fs/mnt_idmapping: introduce an invalid_mnt_idmap

[Aleksandr Mikhalitsyn]

Gentle ping :)

On Fri, Sep 6, 2024 at 4:35 PM Alexander Mikhalitsyn
<aleksandr.mikhalitsyn@canonical.com> wrote:
>
> Link: https://lore.kernel.org/linux-fsdevel/20240904-baugrube-erhoben-b3c1c49a2645@brauner/
> Suggested-by: Christian Brauner <brauner@kernel.org>
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
> ---
>  fs/mnt_idmapping.c            | 22 ++++++++++++++++++++--
>  include/linux/mnt_idmapping.h |  1 +
>  2 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/fs/mnt_idmapping.c b/fs/mnt_idmapping.c
> index 3c60f1eaca61..cbca6500848e 100644
> --- a/fs/mnt_idmapping.c
> +++ b/fs/mnt_idmapping.c
> @@ -32,6 +32,15 @@ struct mnt_idmap nop_mnt_idmap = {
>  };
>  EXPORT_SYMBOL_GPL(nop_mnt_idmap);
>
> +/*
> + * Carries the invalid idmapping of a full 0-4294967295 {g,u}id range.
> + * This means that all {g,u}ids are mapped to INVALID_VFS{G,U}ID.
> + */
> +struct mnt_idmap invalid_mnt_idmap = {
> +       .count  = REFCOUNT_INIT(1),
> +};
> +EXPORT_SYMBOL_GPL(invalid_mnt_idmap);
> +
>  /**
>   * initial_idmapping - check whether this is the initial mapping
>   * @ns: idmapping to check
> @@ -75,6 +84,8 @@ vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
>
>         if (idmap == &nop_mnt_idmap)
>                 return VFSUIDT_INIT(kuid);
> +       if (idmap == &invalid_mnt_idmap)
> +               return INVALID_VFSUID;
>         if (initial_idmapping(fs_userns))
>                 uid = __kuid_val(kuid);
>         else
> @@ -112,6 +123,8 @@ vfsgid_t make_vfsgid(struct mnt_idmap *idmap,
>
>         if (idmap == &nop_mnt_idmap)
>                 return VFSGIDT_INIT(kgid);
> +       if (idmap == &invalid_mnt_idmap)
> +               return INVALID_VFSGID;
>         if (initial_idmapping(fs_userns))
>                 gid = __kgid_val(kgid);
>         else
> @@ -140,6 +153,8 @@ kuid_t from_vfsuid(struct mnt_idmap *idmap,
>
>         if (idmap == &nop_mnt_idmap)
>                 return AS_KUIDT(vfsuid);
> +       if (idmap == &invalid_mnt_idmap)
> +               return INVALID_UID;
>         uid = map_id_up(&idmap->uid_map, __vfsuid_val(vfsuid));
>         if (uid == (uid_t)-1)
>                 return INVALID_UID;
> @@ -167,6 +182,8 @@ kgid_t from_vfsgid(struct mnt_idmap *idmap,
>
>         if (idmap == &nop_mnt_idmap)
>                 return AS_KGIDT(vfsgid);
> +       if (idmap == &invalid_mnt_idmap)
> +               return INVALID_GID;
>         gid = map_id_up(&idmap->gid_map, __vfsgid_val(vfsgid));
>         if (gid == (gid_t)-1)
>                 return INVALID_GID;
> @@ -296,7 +313,7 @@ struct mnt_idmap *alloc_mnt_idmap(struct user_namespace *mnt_userns)
>   */
>  struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap)
>  {
> -       if (idmap != &nop_mnt_idmap)
> +       if (idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap)
>                 refcount_inc(&idmap->count);
>
>         return idmap;
> @@ -312,7 +329,8 @@ EXPORT_SYMBOL_GPL(mnt_idmap_get);
>   */
>  void mnt_idmap_put(struct mnt_idmap *idmap)
>  {
> -       if (idmap != &nop_mnt_idmap && refcount_dec_and_test(&idmap->count))
> +       if (idmap != &nop_mnt_idmap && idmap != &invalid_mnt_idmap &&
> +           refcount_dec_and_test(&idmap->count))
>                 free_mnt_idmap(idmap);
>  }
>  EXPORT_SYMBOL_GPL(mnt_idmap_put);
> diff --git a/include/linux/mnt_idmapping.h b/include/linux/mnt_idmapping.h
> index cd4d5c8781f5..b1b219bc3422 100644
> --- a/include/linux/mnt_idmapping.h
> +++ b/include/linux/mnt_idmapping.h
> @@ -9,6 +9,7 @@ struct mnt_idmap;
>  struct user_namespace;
>
>  extern struct mnt_idmap nop_mnt_idmap;
> +extern struct mnt_idmap invalid_mnt_idmap;
>  extern struct user_namespace init_user_ns;
>
>  typedef struct {
> --
> 2.34.1
>