[PATCH 06/11] iov_iter: handle the compat case in import_iovec

Christoph Hellwig
2020-09-21T14:36:02Z

Use in compat_syscall to import either native or the compat iovecs, and
remove the now superflous compat_import_iovec, which removes the need for
special compat logic in most callers. Only io_uring needs special
treatment given that it can call import_iovec from kernel threads acting
on behalf of native or compat syscalls. Expose the low-level
__import_iovec helper and use it in io_uring to explicitly pick a iovec
layout.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/scsi_ioctl.c | 12 ++----------
drivers/scsi/sg.c | 9 +--------
fs/aio.c | 38 ++++++++++++++------------------------
fs/io_uring.c | 20 ++++++++------------
fs/read_write.c | 6 ++++--
fs/splice.c | 2 +-
include/linux/uio.h | 10 +++-------
lib/iov_iter.c | 17 +++--------------
mm/process_vm_access.c | 7 ++++---
net/compat.c | 4 ++--
security/keys/compat.c | 5 ++---
11 files changed, 44 insertions(+), 86 deletions(-)

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index ef722f04f88a93..e08df86866ee5d 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -333,16 +333,8 @@ static int sg_io(struct request_queue *q, struct gendisk *bd_disk,
struct iov_iter i;
struct iovec *iov = NULL;

-#ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- ret = compat_import_iovec(rq_data_dir(rq),
- hdr->dxferp, hdr->iovec_count,
- 0, &iov, &i);
- else
-#endif
- ret = import_iovec(rq_data_dir(rq),
- hdr->dxferp, hdr->iovec_count,
- 0, &iov, &i);
+ ret = import_iovec(rq_data_dir(rq), hdr->dxferp,
+ hdr->iovec_count, 0, &iov, &i);
if (ret < 0)
goto out_free_cdb;

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 20472aaaf630a4..bfa8d77322d732 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1820,14 +1820,7 @@ sg_start_req(Sg_request *srp, unsigned char *cmd)
struct iovec *iov = NULL;
struct iov_iter i;

-#ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- res = compat_import_iovec(rw, hp->dxferp, iov_count,
- 0, &iov, &i);
- else
-#endif
- res = import_iovec(rw, hp->dxferp, iov_count,
- 0, &iov, &i);
+ res = import_iovec(rw, hp->dxferp, iov_count, 0, &iov, &i);
if (res < 0)
return res;

diff --git a/fs/aio.c b/fs/aio.c
index d5ec303855669d..b377f5c2048e18 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1478,8 +1478,7 @@ static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
}

static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
- struct iovec **iovec, bool vectored, bool compat,
- struct iov_iter *iter)
+ struct iovec **iovec, bool vectored, struct iov_iter *iter)
{
void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
size_t len = iocb->aio_nbytes;
@@ -1489,11 +1488,6 @@ static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
*iovec = NULL;
return ret;
}
-#ifdef CONFIG_COMPAT
- if (compat)
- return compat_import_iovec(rw, buf, len, UIO_FASTIOV, iovec,
- iter);
-#endif
return import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter);
}

@@ -1517,8 +1511,7 @@ static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
}
}

-static int aio_read(struct kiocb *req, const struct iocb *iocb,
- bool vectored, bool compat)
+static int aio_read(struct kiocb *req, const struct iocb *iocb, bool vectored)
{
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
struct iov_iter iter;
@@ -1535,7 +1528,7 @@ static int aio_read(struct kiocb *req, const struct iocb *iocb,
if (unlikely(!file->f_op->read_iter))
return -EINVAL;

- ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
+ ret = aio_setup_rw(READ, iocb, &iovec, vectored, &iter);
if (ret < 0)
return ret;
ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
@@ -1545,8 +1538,7 @@ static int aio_read(struct kiocb *req, const struct iocb *iocb,
return ret;
}

-static int aio_write(struct kiocb *req, const struct iocb *iocb,
- bool vectored, bool compat)
+static int aio_write(struct kiocb *req, const struct iocb *iocb, bool vectored)
{
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
struct iov_iter iter;
@@ -1563,7 +1555,7 @@ static int aio_write(struct kiocb *req, const struct iocb *iocb,
if (unlikely(!file->f_op->write_iter))
return -EINVAL;

- ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
+ ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, &iter);
if (ret < 0)
return ret;
ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
@@ -1799,8 +1791,7 @@ static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
}

static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
- struct iocb __user *user_iocb, struct aio_kiocb *req,
- bool compat)
+ struct iocb __user *user_iocb, struct aio_kiocb *req)
{
req->ki_filp = fget(iocb->aio_fildes);
if (unlikely(!req->ki_filp))
@@ -1833,13 +1824,13 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,

switch (iocb->aio_lio_opcode) {
case IOCB_CMD_PREAD:
- return aio_read(&req->rw, iocb, false, compat);
+ return aio_read(&req->rw, iocb, false);
case IOCB_CMD_PWRITE:
- return aio_write(&req->rw, iocb, false, compat);
+ return aio_write(&req->rw, iocb, false);
case IOCB_CMD_PREADV:
- return aio_read(&req->rw, iocb, true, compat);
+ return aio_read(&req->rw, iocb, true);
case IOCB_CMD_PWRITEV:
- return aio_write(&req->rw, iocb, true, compat);
+ return aio_write(&req->rw, iocb, true);
case IOCB_CMD_FSYNC:
return aio_fsync(&req->fsync, iocb, false);
case IOCB_CMD_FDSYNC:
@@ -1852,8 +1843,7 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
}
}

-static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
- bool compat)
+static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb)
{
struct aio_kiocb *req;
struct iocb iocb;
@@ -1882,7 +1872,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
if (unlikely(!req))
return -EAGAIN;

- err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
+ err = __io_submit_one(ctx, &iocb, user_iocb, req);

/* Done with the synchronous reference */
iocb_put(req);
@@ -1941,7 +1931,7 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
break;
}

- ret = io_submit_one(ctx, user_iocb, false);
+ ret = io_submit_one(ctx, user_iocb);
if (ret)
break;
}
@@ -1983,7 +1973,7 @@ COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
break;
}

- ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
+ ret = io_submit_one(ctx, compat_ptr(user_iocb));
if (ret)
break;
}
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3790c7fe9fee22..ba84ecea7cb1a4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2837,13 +2837,8 @@ static ssize_t __io_import_iovec(int rw, struct io_kiocb *req,
return ret;
}

-#ifdef CONFIG_COMPAT
- if (req->ctx->compat)
- return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
- iovec, iter);
-#endif
-
- return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
+ return __import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter,
+ req->ctx->compat);
}

static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
@@ -4179,8 +4174,9 @@ static int __io_recvmsg_copy_hdr(struct io_kiocb *req,
sr->len);
iomsg->iov = NULL;
} else {
- ret = import_iovec(READ, uiov, iov_len, UIO_FASTIOV,
- &iomsg->iov, &iomsg->msg.msg_iter);
+ ret = __import_iovec(READ, uiov, iov_len, UIO_FASTIOV,
+ &iomsg->iov, &iomsg->msg.msg_iter,
+ false);
if (ret > 0)
ret = 0;
}
@@ -4220,9 +4216,9 @@ static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
sr->len = iomsg->iov[0].iov_len;
iomsg->iov = NULL;
} else {
- ret = compat_import_iovec(READ, uiov, len, UIO_FASTIOV,
- &iomsg->iov,
- &iomsg->msg.msg_iter);
+ ret = __import_iovec(READ, (struct iovec __user *)uiov, len,
+ UIO_FASTIOV, &iomsg->iov,
+ &iomsg->msg.msg_iter, true);
if (ret < 0)
return ret;
}
diff --git a/fs/read_write.c b/fs/read_write.c
index e5e891a88442ef..0a68037580b455 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1078,7 +1078,8 @@ static size_t compat_readv(struct file *file,
struct iov_iter iter;
ssize_t ret;

- ret = compat_import_iovec(READ, vec, vlen, UIO_FASTIOV, &iov, &iter);
+ ret = import_iovec(READ, (const struct iovec __user *)vec, vlen,
+ UIO_FASTIOV, &iov, &iter);
if (ret >= 0) {
ret = do_iter_read(file, &iter, pos, flags);
kfree(iov);
@@ -1186,7 +1187,8 @@ static size_t compat_writev(struct file *file,
struct iov_iter iter;
ssize_t ret;

- ret = compat_import_iovec(WRITE, vec, vlen, UIO_FASTIOV, &iov, &iter);
+ ret = import_iovec(WRITE, (const struct iovec __user *)vec, vlen,
+ UIO_FASTIOV, &iov, &iter);
if (ret >= 0) {
file_start_write(file);
ret = do_iter_write(file, &iter, pos, flags);
diff --git a/fs/splice.c b/fs/splice.c
index d7c8a7c4db07ff..132d42b9871f9b 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1387,7 +1387,7 @@ COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, io
if (error)
return error;

- error = compat_import_iovec(type, iov32, nr_segs,
+ error = import_iovec(type, (struct iovec __user *)iov32, nr_segs,
ARRAY_SIZE(iovstack), &iov, &iter);
if (error >= 0) {
error = do_vmsplice(f.file, &iter, flags);
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 3835a8a8e9eae0..fff5d49dd0d53e 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -269,13 +269,9 @@ size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
ssize_t import_iovec(int type, const struct iovec __user * uvector,
unsigned nr_segs, unsigned fast_segs,
struct iovec **iov, struct iov_iter *i);
-
-#ifdef CONFIG_COMPAT
-struct compat_iovec;
-ssize_t compat_import_iovec(int type, const struct compat_iovec __user * uvector,
- unsigned nr_segs, unsigned fast_segs,
- struct iovec **iov, struct iov_iter *i);
-#endif
+ssize_t __import_iovec(int type, const struct iovec __user *uvector,
+ unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
+ struct iov_iter *i, bool compat);

int import_single_range(int type, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 8bfa47b63d39aa..632265178d8737 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1683,7 +1683,7 @@ static int compat_copy_iovecs_from_user(struct iovec *iov,
return ret;
}

-static ssize_t __import_iovec(int type, const struct iovec __user *uvector,
+ssize_t __import_iovec(int type, const struct iovec __user *uvector,
unsigned nr_segs, unsigned fast_segs, struct iovec **iovp,
struct iov_iter *i, bool compat)
{
@@ -1793,22 +1793,11 @@ ssize_t import_iovec(int type, const struct iovec __user * uvector,
unsigned nr_segs, unsigned fast_segs,
struct iovec **iov, struct iov_iter *i)
{
- return __import_iovec(type, uvector, nr_segs, fast_segs, iov, i, false);
+ return __import_iovec(type, uvector, nr_segs, fast_segs, iov, i,
+ in_compat_syscall());
}
EXPORT_SYMBOL(import_iovec);

-#ifdef CONFIG_COMPAT
-ssize_t compat_import_iovec(int type,
- const struct compat_iovec __user * uvector,
- unsigned nr_segs, unsigned fast_segs,
- struct iovec **iov, struct iov_iter *i)
-{
- return __import_iovec(type, (const struct iovec __user *)uvector,
- nr_segs, fast_segs, iov, i, true);
-}
-EXPORT_SYMBOL(compat_import_iovec);
-#endif
-
int import_single_range(int rw, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i)
{
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 40cd502c337534..b759ed264840d8 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -331,13 +331,14 @@ compat_process_vm_rw(compat_pid_t pid,
if (flags != 0)
return -EINVAL;

- rc = compat_import_iovec(dir, lvec, liovcnt, UIO_FASTIOV, &iov_l, &iter_l);
+ rc = import_iovec(dir, (const struct iovec __user *)iov_l, liovcnt,
+ UIO_FASTIOV, &iov_l, &iter_l);
if (rc < 0)
return rc;
if (!iov_iter_count(&iter_l))
goto free_iovecs;
- rc = compat_import_iovec(CHECK_IOVEC_ONLY, rvec, riovcnt, UIO_FASTIOV,
- &iov_r, &iter_r);
+ rc = import_iovec(CHECK_IOVEC_ONLY, iov_r, riovcnt, UIO_FASTIOV, &iov_r,
+ &iter_r);
if (rc <= 0)
goto free_iovecs;

diff --git a/net/compat.c b/net/compat.c
index 95ce707a30a31d..ddd15af3a2837b 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -98,8 +98,8 @@ int get_compat_msghdr(struct msghdr *kmsg,
if (err)
return err;

- err = compat_import_iovec(save_addr ? READ : WRITE, compat_ptr(ptr),
- len, UIO_FASTIOV, iov, &kmsg->msg_iter);
+ err = import_iovec(save_addr ? READ : WRITE, compat_ptr(ptr), len,
+ UIO_FASTIOV, iov, &kmsg->msg_iter);
return err < 0 ? err : 0;
}

diff --git a/security/keys/compat.c b/security/keys/compat.c
index 6ee9d8f6a4a5bb..7ae531db031cf8 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -33,9 +33,8 @@ static long compat_keyctl_instantiate_key_iov(
if (!_payload_iov)
ioc = 0;

- ret = compat_import_iovec(WRITE, _payload_iov, ioc,
- ARRAY_SIZE(iovstack), &iov,
- &from);
+ ret = import_iovec(WRITE, (const struct iovec __user *)_payload_iov,
+ ioc, ARRAY_SIZE(iovstack), &iov, &from);
if (ret < 0)
return ret;

--
2.28.0