Re: [PATCH 7/8] fuse: propagate default and file acls on creation

Chen Linxuan
2025-09-16T06:41:44Z

On Tue, Sep 16, 2025 at 8:26 AM Darrick J. Wong <djwong@kernel.org> wrote:
>
> From: Darrick J. Wong <djwong@kernel.org>
>
> For local filesystems, propagate the default and file access ACLs to new
> children when creating them, just like the other in-kernel local
> filesystems.
>
> Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> ---
> fs/fuse/fuse_i.h | 4 ++
> fs/fuse/acl.c | 65 ++++++++++++++++++++++++++++++++++++++
> fs/fuse/dir.c | 92 +++++++++++++++++++++++++++++++++++++++++-------------
> 3 files changed, 138 insertions(+), 23 deletions(-)
>
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 52776b77efc0e4..b9306678dcda0d 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -1507,6 +1507,10 @@ struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap,
> struct dentry *dentry, int type);
> int fuse_set_acl(struct mnt_idmap *, struct dentry *dentry,
> struct posix_acl *acl, int type);
> +int fuse_acl_create(struct inode *dir, umode_t *mode,
> + struct posix_acl **default_acl, struct posix_acl **acl);
> +int fuse_init_acls(struct inode *inode, const struct posix_acl *default_acl,
> + const struct posix_acl *acl);
>
> /* readdir.c */
> int fuse_readdir(struct file *file, struct dir_context *ctx);
> diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
> index 4997827ee83c6d..4faee72f1365a5 100644
> --- a/fs/fuse/acl.c
> +++ b/fs/fuse/acl.c
> @@ -203,3 +203,68 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
>
> return ret;
> }
> +
> +int fuse_acl_create(struct inode *dir, umode_t *mode,
> + struct posix_acl **default_acl, struct posix_acl **acl)
> +{
> + struct fuse_conn *fc = get_fuse_conn(dir);
> +
> + if (fuse_is_bad(dir))
> + return -EIO;
> +
> + if (IS_POSIXACL(dir) && fuse_has_local_acls(fc))
> + return posix_acl_create(dir, mode, default_acl, acl);
> +
> + if (!fc->dont_mask)
> + *mode &= ~current_umask();
> +
> + *default_acl = NULL;
> + *acl = NULL;
> + return 0;
> +}
> +
> +static int __fuse_set_acl(struct inode *inode, const char *name,
> + const struct posix_acl *acl)
> +{
> + struct fuse_conn *fc = get_fuse_conn(inode);
> + size_t size = posix_acl_xattr_size(acl->a_count);
> + void *value;
> + int ret;
> +
> + if (size > PAGE_SIZE)
> + return -E2BIG;
> +
> + value = kmalloc(size, GFP_KERNEL);
> + if (!value)
> + return -ENOMEM;
> +
> + ret = posix_acl_to_xattr(fc->user_ns, acl, value, size);
> + if (ret < 0)
> + goto out_value;
> +
> + ret = fuse_setxattr(inode, name, value, size, 0, 0);
> +out_value:
> + kfree(value);
> + return ret;
> +}
> +
> +int fuse_init_acls(struct inode *inode, const struct posix_acl *default_acl,
> + const struct posix_acl *acl)
> +{
> + int ret;
> +
> + if (default_acl) {
> + ret = __fuse_set_acl(inode, XATTR_NAME_POSIX_ACL_DEFAULT,
> + default_acl);
> + if (ret)
> + return ret;
> + }
> +
> + if (acl) {
> + ret = __fuse_set_acl(inode, XATTR_NAME_POSIX_ACL_ACCESS, acl);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
> index a7f47e43692f1c..b116e42431ee12 100644
> --- a/fs/fuse/dir.c
> +++ b/fs/fuse/dir.c
> @@ -628,26 +628,28 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
> struct fuse_entry_out outentry;
> struct fuse_inode *fi;
> struct fuse_file *ff;
> + struct posix_acl *default_acl = NULL, *acl = NULL;
> int epoch, err;
> bool trunc = flags & O_TRUNC;
>
> /* Userspace expects S_IFREG in create mode */
> BUG_ON((mode & S_IFMT) != S_IFREG);
>
> + err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> + if (err)
> + return err;
> +
> epoch = atomic_read(&fm->fc->epoch);
> forget = fuse_alloc_forget();
> err = -ENOMEM;
> if (!forget)
> - goto out_err;
> + goto out_acl_release;
>
> err = -ENOMEM;
> ff = fuse_file_alloc(fm, true);
> if (!ff)
> goto out_put_forget_req;
>
> - if (!fm->fc->dont_mask)
> - mode &= ~current_umask();
> -
> flags &= ~O_NOCTTY;
> memset(&inarg, 0, sizeof(inarg));
> memset(&outentry, 0, sizeof(outentry));
> @@ -699,12 +701,16 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
> fuse_sync_release(NULL, ff, flags);
> fuse_queue_forget(fm->fc, forget, outentry.nodeid, 1);
> err = -ENOMEM;
> - goto out_err;
> + goto out_acl_release;
> }
> kfree(forget);
> d_instantiate(entry, inode);
> entry->d_time = epoch;
> fuse_change_entry_timeout(entry, &outentry);
> +
> + err = fuse_init_acls(inode, default_acl, acl);
> + if (err)
> + goto out_acl_release;
> fuse_dir_changed(dir);
> err = generic_file_open(inode, file);
> if (!err) {
> @@ -726,7 +732,9 @@ static int fuse_create_open(struct mnt_idmap *idmap, struct inode *dir,
> fuse_file_free(ff);
> out_put_forget_req:
> kfree(forget);
> -out_err:
> +out_acl_release:
> + posix_acl_release(default_acl);
> + posix_acl_release(acl);
> return err;
> }
>
> @@ -785,7 +793,9 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
> */
> static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_mount *fm,
> struct fuse_args *args, struct inode *dir,
> - struct dentry *entry, umode_t mode)
> + struct dentry *entry, umode_t mode,
> + struct posix_acl *default_acl,
> + struct posix_acl *acl)
> {
> struct fuse_entry_out outarg;
> struct inode *inode;
> @@ -793,14 +803,18 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
> struct fuse_forget_link *forget;
> int epoch, err;
>
> - if (fuse_is_bad(dir))
> - return ERR_PTR(-EIO);
> + if (fuse_is_bad(dir)) {
> + err = -EIO;
> + goto out_acl_release;
> + }
>
> epoch = atomic_read(&fm->fc->epoch);
>
> forget = fuse_alloc_forget();
> - if (!forget)
> - return ERR_PTR(-ENOMEM);
> + if (!forget) {
> + err = -ENOMEM;
> + goto out_acl_release;
> + }
>
> memset(&outarg, 0, sizeof(outarg));
> args->nodeid = get_node_id(dir);
> @@ -830,7 +844,8 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
> &outarg.attr, ATTR_TIMEOUT(&outarg), 0, 0);
> if (!inode) {
> fuse_queue_forget(fm->fc, forget, outarg.nodeid, 1);
> - return ERR_PTR(-ENOMEM);
> + err = -ENOMEM;
> + goto out_acl_release;
> }
> kfree(forget);
>
> @@ -846,19 +861,31 @@ static struct dentry *create_new_entry(struct mnt_idmap *idmap, struct fuse_moun
> entry->d_time = epoch;
> fuse_change_entry_timeout(entry, &outarg);
> }
> +
> + err = fuse_init_acls(inode, default_acl, acl);
> + if (err)
> + goto out_acl_release;
> fuse_dir_changed(dir);
> +
> + posix_acl_release(default_acl);
> + posix_acl_release(acl);
> return d;
>
> out_put_forget_req:
> if (err == -EEXIST)
> fuse_invalidate_entry(entry);
> kfree(forget);
> + out_acl_release:
> + posix_acl_release(default_acl);
> + posix_acl_release(acl);
> return ERR_PTR(err);
> }
>
> static int create_new_nondir(struct mnt_idmap *idmap, struct fuse_mount *fm,
> struct fuse_args *args, struct inode *dir,
> - struct dentry *entry, umode_t mode)
> + struct dentry *entry, umode_t mode,
> + struct posix_acl *default_acl,
> + struct posix_acl *acl)
> {
> /*
> * Note that when creating anything other than a directory we
> @@ -869,7 +896,8 @@ static int create_new_nondir(struct mnt_idmap *idmap, struct fuse_mount *fm,
> */
> WARN_ON_ONCE(S_ISDIR(mode));
>
> - return PTR_ERR(create_new_entry(idmap, fm, args, dir, entry, mode));
> + return PTR_ERR(create_new_entry(idmap, fm, args, dir, entry, mode,
> + default_acl, acl));
> }
>
> static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
> @@ -877,10 +905,13 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
> {
> struct fuse_mknod_in inarg;
> struct fuse_mount *fm = get_fuse_mount(dir);
> + struct posix_acl *default_acl, *acl;
> FUSE_ARGS(args);
> + int err;
>
> - if (!fm->fc->dont_mask)
> - mode &= ~current_umask();
> + err = fuse_acl_create(dir, &mode, &default_acl, &acl);

Please excuse me if this is a dumb question.
In this function (including fuse_mkdir and fuse_symlink),
why can't we pair fuse_acl_create and posix_acl_release together
within the same function,
just like in fuse_create_open?

Thanks,
Chen Linxuan

> + if (err)
> + return err;
>
> memset(&inarg, 0, sizeof(inarg));
> inarg.mode = mode;
> @@ -892,7 +923,8 @@ static int fuse_mknod(struct mnt_idmap *idmap, struct inode *dir,
> args.in_args[0].value = &inarg;
> args.in_args[1].size = entry->d_name.len + 1;
> args.in_args[1].value = entry->d_name.name;
> - return create_new_nondir(idmap, fm, &args, dir, entry, mode);
> + return create_new_nondir(idmap, fm, &args, dir, entry, mode,
> + default_acl, acl);
> }
>
> static int fuse_create(struct mnt_idmap *idmap, struct inode *dir,
> @@ -924,13 +956,17 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> {
> struct fuse_mkdir_in inarg;
> struct fuse_mount *fm = get_fuse_mount(dir);
> + struct posix_acl *default_acl, *acl;
> FUSE_ARGS(args);
> + int err;
>
> - if (!fm->fc->dont_mask)
> - mode &= ~current_umask();
> + mode |= S_IFDIR; /* vfs doesn't set S_IFDIR for us */
> + err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> + if (err)
> + return ERR_PTR(err);
>
> memset(&inarg, 0, sizeof(inarg));
> - inarg.mode = mode;
> + inarg.mode = mode & ~S_IFDIR;
> inarg.umask = current_umask();
> args.opcode = FUSE_MKDIR;
> args.in_numargs = 2;
> @@ -938,7 +974,8 @@ static struct dentry *fuse_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> args.in_args[0].value = &inarg;
> args.in_args[1].size = entry->d_name.len + 1;
> args.in_args[1].value = entry->d_name.name;
> - return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR);
> + return create_new_entry(idmap, fm, &args, dir, entry, S_IFDIR,
> + default_acl, acl);
> }
>
> static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> @@ -946,7 +983,14 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> {
> struct fuse_mount *fm = get_fuse_mount(dir);
> unsigned len = strlen(link) + 1;
> + struct posix_acl *default_acl, *acl;
> + umode_t mode = S_IFLNK | 0777;
> FUSE_ARGS(args);
> + int err;
> +
> + err = fuse_acl_create(dir, &mode, &default_acl, &acl);
> + if (err)
> + return err;
>
> args.opcode = FUSE_SYMLINK;
> args.in_numargs = 3;
> @@ -955,7 +999,8 @@ static int fuse_symlink(struct mnt_idmap *idmap, struct inode *dir,
> args.in_args[1].value = entry->d_name.name;
> args.in_args[2].size = len;
> args.in_args[2].value = link;
> - return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK);
> + return create_new_nondir(idmap, fm, &args, dir, entry, S_IFLNK,
> + default_acl, acl);
> }
>
> void fuse_flush_time_update(struct inode *inode)
> @@ -1155,7 +1200,8 @@ 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_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent, inode->i_mode);
> + err = create_new_nondir(&invalid_mnt_idmap, fm, &args, newdir, newent,
> + inode->i_mode, NULL, NULL);
> if (!err)
> fuse_update_ctime_in_cache(inode);
> else if (err == -EINTR)
>
>
>