io_uring: add support for IORING_OP_SYMLINKAT

IORING_OP_SYMLINKAT behaves like symlinkat(2) and takes the same flags
and arguments.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/io-uring/20210514145259.wtl4xcsp52woi6ab@wittgenstein/
Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20210708063447.3556403-11-dkadashev@gmail.com
[axboe: add splice_fd_in check]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/internal.h b/fs/internal.h
index d6b15da..2f9750a 100644 (file)
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -77,6 +77,7 @@ int may_linkat(struct user_namespace *mnt_userns, struct path *link);
 int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
                 struct filename *newname, unsigned int flags);
 int do_mkdirat(int dfd, struct filename *name, umode_t mode);
+int do_symlinkat(struct filename *from, int newdfd, struct filename *to);
 
 /*
  * namespace.c

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 8e14e71..33941df 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -669,6 +669,13 @@ struct io_mkdir {
        struct filename                 *filename;
 };
 
+struct io_symlink {
+       struct file                     *file;
+       int                             new_dfd;
+       struct filename                 *oldpath;
+       struct filename                 *newpath;
+};
+
 struct io_completion {
        struct file                     *file;
        u32                             cflags;
@@ -829,6 +836,7 @@ struct io_kiocb {
                struct io_rename        rename;
                struct io_unlink        unlink;
                struct io_mkdir         mkdir;
+               struct io_symlink       symlink;
                /* use only after cleaning per-op data, see io_clean_op() */
                struct io_completion    compl;
        };
@@ -1041,6 +1049,7 @@ static const struct io_op_def io_op_defs[] = {
        [IORING_OP_RENAMEAT] = {},
        [IORING_OP_UNLINKAT] = {},
        [IORING_OP_MKDIRAT] = {},
+       [IORING_OP_SYMLINKAT] = {},
 };
 
 /* requests with any of those set should undergo io_disarm_next() */
@@ -3655,6 +3664,55 @@ static int io_mkdirat(struct io_kiocb *req, int issue_flags)
        return 0;
 }
 
+static int io_symlinkat_prep(struct io_kiocb *req,
+                           const struct io_uring_sqe *sqe)
+{
+       struct io_symlink *sl = &req->symlink;
+       const char __user *oldpath, *newpath;
+
+       if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+               return -EINVAL;
+       if (sqe->ioprio || sqe->len || sqe->rw_flags || sqe->buf_index ||
+           sqe->splice_fd_in)
+               return -EINVAL;
+       if (unlikely(req->flags & REQ_F_FIXED_FILE))
+               return -EBADF;
+
+       sl->new_dfd = READ_ONCE(sqe->fd);
+       oldpath = u64_to_user_ptr(READ_ONCE(sqe->addr));
+       newpath = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+
+       sl->oldpath = getname(oldpath);
+       if (IS_ERR(sl->oldpath))
+               return PTR_ERR(sl->oldpath);
+
+       sl->newpath = getname(newpath);
+       if (IS_ERR(sl->newpath)) {
+               putname(sl->oldpath);
+               return PTR_ERR(sl->newpath);
+       }
+
+       req->flags |= REQ_F_NEED_CLEANUP;
+       return 0;
+}
+
+static int io_symlinkat(struct io_kiocb *req, int issue_flags)
+{
+       struct io_symlink *sl = &req->symlink;
+       int ret;
+
+       if (issue_flags & IO_URING_F_NONBLOCK)
+               return -EAGAIN;
+
+       ret = do_symlinkat(sl->oldpath, sl->new_dfd, sl->newpath);
+
+       req->flags &= ~REQ_F_NEED_CLEANUP;
+       if (ret < 0)
+               req_set_fail(req);
+       io_req_complete(req, ret);
+       return 0;
+}
+
 static int io_shutdown_prep(struct io_kiocb *req,
                            const struct io_uring_sqe *sqe)
 {
@@ -6054,6 +6112,8 @@ static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
                return io_unlinkat_prep(req, sqe);
        case IORING_OP_MKDIRAT:
                return io_mkdirat_prep(req, sqe);
+       case IORING_OP_SYMLINKAT:
+               return io_symlinkat_prep(req, sqe);
        }
 
        printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
@@ -6220,6 +6280,10 @@ static void io_clean_op(struct io_kiocb *req)
                case IORING_OP_MKDIRAT:
                        putname(req->mkdir.filename);
                        break;
+               case IORING_OP_SYMLINKAT:
+                       putname(req->symlink.oldpath);
+                       putname(req->symlink.newpath);
+                       break;
                }
        }
        if ((req->flags & REQ_F_POLLED) && req->apoll) {
@@ -6351,6 +6415,9 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
        case IORING_OP_MKDIRAT:
                ret = io_mkdirat(req, issue_flags);
                break;
+       case IORING_OP_SYMLINKAT:
+               ret = io_symlinkat(req, issue_flags);
+               break;
        default:
                ret = -EINVAL;
                break;

diff --git a/fs/namei.c b/fs/namei.c
index e2425c0..803fc95 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4223,8 +4223,7 @@ int vfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 }
 EXPORT_SYMBOL(vfs_symlink);
 
-static int do_symlinkat(struct filename *from, int newdfd,
-                 struct filename *to)
+int do_symlinkat(struct filename *from, int newdfd, struct filename *to)
 {
        int error;
        struct dentry *dentry;

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index a926407..61fd347 100644 (file)
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -134,6 +134,7 @@ enum {
        IORING_OP_RENAMEAT,
        IORING_OP_UNLINKAT,
        IORING_OP_MKDIRAT,
+       IORING_OP_SYMLINKAT,
 
        /* this goes last, obviously */
        IORING_OP_LAST,