From: Jens Axboe axboe@kernel.dk
mainline inclusion from mainline-5.8-rc1 commit fd2206e4e97b5bae422d9f2f9ebbc79bc97e44a5 category: feature bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27 CVE: NA ---------------------------
A previous commit enabled this functionality, which also enabled O_PATH to work correctly with io_uring. But we can't safely close the ring itself, as the file handle isn't reference counted inside io_uring_enter(). Instead of jumping through hoops to enable ring closure, add a "soft" ->needs_file option, ->needs_file_no_error. This enables O_PATH file descriptors to work, but still catches the case of trying to close the ring itself.
Reported-by: Jann Horn jannh@google.com Fixes: 904fbcb115c8 ("io_uring: remove 'fd is io_uring' from close path") Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: yangerkun yangerkun@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Cheng Jian cj.chengjian@huawei.com --- fs/io_uring.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 8516dffe6649..aceede48ccf2 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -701,6 +701,8 @@ struct io_op_def { unsigned needs_mm : 1; /* needs req->file assigned */ unsigned needs_file : 1; + /* don't fail if file grab fails */ + unsigned needs_file_no_error : 1; /* hash wq insertion if file is a regular file */ unsigned hash_reg_file : 1; /* unbound wq insertion if file is a non-regular file */ @@ -807,6 +809,8 @@ static const struct io_op_def io_op_defs[] = { .needs_fs = 1, }, [IORING_OP_CLOSE] = { + .needs_file = 1, + .needs_file_no_error = 1, .file_table = 1, }, [IORING_OP_FILES_UPDATE] = { @@ -3371,6 +3375,10 @@ static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) return -EBADF;
req->close.fd = READ_ONCE(sqe->fd); + if ((req->file && req->file->f_op == &io_uring_fops) || + req->close.fd == req->ctx->ring_fd) + return -EBADF; + return 0; }
@@ -5376,19 +5384,20 @@ static int io_file_get(struct io_submit_state *state, struct io_kiocb *req, return -EBADF; fd = array_index_nospec(fd, ctx->nr_user_files); file = io_file_from_index(ctx, fd); - if (!file) - return -EBADF; - req->fixed_file_refs = ctx->file_data->cur_refs; - percpu_ref_get(req->fixed_file_refs); + if (file) { + req->fixed_file_refs = ctx->file_data->cur_refs; + percpu_ref_get(req->fixed_file_refs); + } } else { trace_io_uring_file_get(ctx, fd); file = __io_file_get(state, fd); - if (unlikely(!file)) - return -EBADF; }
- *out_file = file; - return 0; + if (file || io_op_defs[req->opcode].needs_file_no_error) { + *out_file = file; + return 0; + } + return -EBADF; }
static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req,