bpf: convert bpf_token_create() to FD_PREPARE()

Link: https://patch.msgid.link/20251123-work-fd-prepare-v4-24-b6efa1706cfd@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c
index 0bbe412f854e90123daf1fad39b9130aa7eed6f7..feecd8f4dbf920c08a49c492a85f3d20ff51adae 100644 (file)
--- a/kernel/bpf/token.c
+++ b/kernel/bpf/token.c
@@ -110,16 +110,15 @@ const struct file_operations bpf_token_fops = {
 
 int bpf_token_create(union bpf_attr *attr)
 {
+       struct bpf_token *token __free(kfree) = NULL;
        struct bpf_mount_opts *mnt_opts;
-       struct bpf_token *token = NULL;
        struct user_namespace *userns;
        struct inode *inode;
-       struct file *file;
        CLASS(fd, f)(attr->token_create.bpffs_fd);
        struct path path;
        struct super_block *sb;
        umode_t mode;
-       int err, fd;
+       int err;
 
        if (fd_empty(f))
                return -EBADF;
@@ -166,23 +165,20 @@ int bpf_token_create(union bpf_attr *attr)
        inode->i_fop = &bpf_token_fops;
        clear_nlink(inode); /* make sure it is unlinked */
 
-       file = alloc_file_pseudo(inode, path.mnt, BPF_TOKEN_INODE_NAME, O_RDWR, &bpf_token_fops);
-       if (IS_ERR(file)) {
-               iput(inode);
-               return PTR_ERR(file);
-       }
+       FD_PREPARE(fdf, O_CLOEXEC,
+                  alloc_file_pseudo(inode, path.mnt, BPF_TOKEN_INODE_NAME,
+                                    O_RDWR, &bpf_token_fops));
+       if (fdf.err)
+               return fdf.err;
 
        token = kzalloc(sizeof(*token), GFP_USER);
-       if (!token) {
-               err = -ENOMEM;
-               goto out_file;
-       }
+       if (!token)
+               return -ENOMEM;
 
        atomic64_set(&token->refcnt, 1);
 
-       /* remember bpffs owning userns for future ns_capable() checks */
-       token->userns = get_user_ns(userns);
-
+       /* remember bpffs owning userns for future ns_capable() checks. */
+       token->userns = userns;
        token->allowed_cmds = mnt_opts->delegate_cmds;
        token->allowed_maps = mnt_opts->delegate_maps;
        token->allowed_progs = mnt_opts->delegate_progs;
@@ -190,24 +186,11 @@ int bpf_token_create(union bpf_attr *attr)
 
        err = security_bpf_token_create(token, attr, &path);
        if (err)
-               goto out_token;
-
-       fd = get_unused_fd_flags(O_CLOEXEC);
-       if (fd < 0) {
-               err = fd;
-               goto out_token;
-       }
-
-       file->private_data = token;
-       fd_install(fd, file);
-
-       return fd;
+               return err;
 
-out_token:
-       bpf_token_free(token);
-out_file:
-       fput(file);
-       return err;
+       get_user_ns(token->userns);
+       fd_prepare_file(fdf)->private_data = no_free_ptr(token);
+       return fd_publish(fdf);
 }
 
 int bpf_token_get_info_by_fd(struct bpf_token *token,