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authorJens Axboe <axboe@kernel.dk>2023-12-07 20:06:02 -0700
committerJens Axboe <axboe@kernel.dk>2023-12-12 07:42:57 -0700
commitdc18b89ab113e9c6c7a529316ddf7029fb55132d (patch)
tree682c2a5f7e58b4af465e4e59fba5bf417420e2cf /io_uring
parent055c15626a45b1ebc9f2f34981e705e1af171236 (diff)
io_uring/openclose: add support for IORING_OP_FIXED_FD_INSTALL
io_uring can currently open/close regular files or fixed/direct descriptors. Or you can instantiate a fixed descriptor from a regular one, and then close the regular descriptor. But you currently can't turn a purely fixed/direct descriptor into a regular file descriptor. IORING_OP_FIXED_FD_INSTALL adds support for installing a direct descriptor into the normal file table, just like receiving a file descriptor or opening a new file would do. This is all nicely abstracted into receive_fd(), and hence adding support for this is truly trivial. Since direct descriptors are only usable within io_uring itself, it can be useful to turn them into real file descriptors if they ever need to be accessed via normal syscalls. This can either be a transitory thing, or just a permanent transition for a given direct descriptor. By default, new fds are installed with O_CLOEXEC set. The application can disable O_CLOEXEC by setting IORING_FIXED_FD_NO_CLOEXEC in the sqe->install_fd_flags member. Suggested-by: Christian Brauner <brauner@kernel.org> Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
-rw-r--r--io_uring/opdef.c9
-rw-r--r--io_uring/openclose.c44
-rw-r--r--io_uring/openclose.h3
3 files changed, 56 insertions, 0 deletions
diff --git a/io_uring/opdef.c b/io_uring/opdef.c
index 799db44283c7..6705634e5f52 100644
--- a/io_uring/opdef.c
+++ b/io_uring/opdef.c
@@ -469,6 +469,12 @@ const struct io_issue_def io_issue_defs[] = {
.prep = io_eopnotsupp_prep,
#endif
},
+ [IORING_OP_FIXED_FD_INSTALL] = {
+ .needs_file = 1,
+ .audit_skip = 1,
+ .prep = io_install_fixed_fd_prep,
+ .issue = io_install_fixed_fd,
+ },
};
const struct io_cold_def io_cold_defs[] = {
@@ -704,6 +710,9 @@ const struct io_cold_def io_cold_defs[] = {
[IORING_OP_FUTEX_WAITV] = {
.name = "FUTEX_WAITV",
},
+ [IORING_OP_FIXED_FD_INSTALL] = {
+ .name = "FIXED_FD_INSTALL",
+ },
};
const char *io_uring_get_opcode(u8 opcode)
diff --git a/io_uring/openclose.c b/io_uring/openclose.c
index 74fc22461f48..0fe0dd305546 100644
--- a/io_uring/openclose.c
+++ b/io_uring/openclose.c
@@ -31,6 +31,11 @@ struct io_close {
u32 file_slot;
};
+struct io_fixed_install {
+ struct file *file;
+ unsigned int o_flags;
+};
+
static bool io_openat_force_async(struct io_open *open)
{
/*
@@ -254,3 +259,42 @@ err:
io_req_set_res(req, ret, 0);
return IOU_OK;
}
+
+int io_install_fixed_fd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_fixed_install *ifi;
+ unsigned int flags;
+
+ if (sqe->off || sqe->addr || sqe->len || sqe->buf_index ||
+ sqe->splice_fd_in || sqe->addr3)
+ return -EINVAL;
+
+ /* must be a fixed file */
+ if (!(req->flags & REQ_F_FIXED_FILE))
+ return -EBADF;
+
+ flags = READ_ONCE(sqe->install_fd_flags);
+ if (flags & ~IORING_FIXED_FD_NO_CLOEXEC)
+ return -EINVAL;
+
+ /* default to O_CLOEXEC, disable if IORING_FIXED_FD_NO_CLOEXEC is set */
+ ifi = io_kiocb_to_cmd(req, struct io_fixed_install);
+ ifi->o_flags = O_CLOEXEC;
+ if (flags & IORING_FIXED_FD_NO_CLOEXEC)
+ ifi->o_flags = 0;
+
+ return 0;
+}
+
+int io_install_fixed_fd(struct io_kiocb *req, unsigned int issue_flags)
+{
+ struct io_fixed_install *ifi;
+ int ret;
+
+ ifi = io_kiocb_to_cmd(req, struct io_fixed_install);
+ ret = receive_fd(req->file, NULL, ifi->o_flags);
+ if (ret < 0)
+ req_set_fail(req);
+ io_req_set_res(req, ret, 0);
+ return IOU_OK;
+}
diff --git a/io_uring/openclose.h b/io_uring/openclose.h
index 4b1c28d3a66c..8a93c98ad0ad 100644
--- a/io_uring/openclose.h
+++ b/io_uring/openclose.h
@@ -12,3 +12,6 @@ int io_openat2(struct io_kiocb *req, unsigned int issue_flags);
int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_close(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_install_fixed_fd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_install_fixed_fd(struct io_kiocb *req, unsigned int issue_flags);