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SubjectRe: aio: compat_ioctl issue?
Date
Michael Tokarev <mjt@tls.msk.ru> writes:

> Jeff Moyer wrote:
>> Michael Tokarev <mjt@tls.msk.ru> writes:
> []
>>> And when running real thing it crashes. I tested it
>>> on 2.6.32 (trivial corrections to the patch required).
>>
>> Could you just post your version of the patch so I can have a look?
>
> I think there's no need since in 2.6.33 (where your patch applies
> without any offsets) it crashes in exactly the same way:

Sorry for taking so long on this. I only tested the case where niovs >
fast_segs, and I missed an obvious thing: I didn't assign the return
pointer to the proper iovec.

So, this patch should get you going.

Cheers,
Jeff

diff --git a/fs/aio.c b/fs/aio.c
index 1cf12b3..5a38805 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -36,6 +36,7 @@
#include <linux/blkdev.h>
#include <linux/mempool.h>
#include <linux/hash.h>
+#include <linux/compat.h>

#include <asm/kmap_types.h>
#include <asm/uaccess.h>
@@ -1384,13 +1385,20 @@ static ssize_t aio_fsync(struct kiocb *iocb)
return ret;
}

-static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb)
+static ssize_t aio_setup_vectored_rw(int type, struct kiocb *kiocb, bool compat)
{
ssize_t ret;

- ret = rw_copy_check_uvector(type, (struct iovec __user *)kiocb->ki_buf,
- kiocb->ki_nbytes, 1,
- &kiocb->ki_inline_vec, &kiocb->ki_iovec);
+ if (compat)
+ ret = compat_rw_copy_check_uvector(type,
+ (struct compat_iovec __user *)kiocb->ki_buf,
+ kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
+ &kiocb->ki_iovec);
+ else
+ ret = rw_copy_check_uvector(type,
+ (struct iovec __user *)kiocb->ki_buf,
+ kiocb->ki_nbytes, 1, &kiocb->ki_inline_vec,
+ &kiocb->ki_iovec);
if (ret < 0)
goto out;

@@ -1420,7 +1428,7 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb)
* Performs the initial checks and aio retry method
* setup for the kiocb at the time of io submission.
*/
-static ssize_t aio_setup_iocb(struct kiocb *kiocb)
+static ssize_t aio_setup_iocb(struct kiocb *kiocb, bool compat)
{
struct file *file = kiocb->ki_filp;
ssize_t ret = 0;
@@ -1469,7 +1477,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
ret = security_file_permission(file, MAY_READ);
if (unlikely(ret))
break;
- ret = aio_setup_vectored_rw(READ, kiocb);
+ ret = aio_setup_vectored_rw(READ, kiocb, compat);
if (ret)
break;
ret = -EINVAL;
@@ -1483,7 +1491,7 @@ static ssize_t aio_setup_iocb(struct kiocb *kiocb)
ret = security_file_permission(file, MAY_WRITE);
if (unlikely(ret))
break;
- ret = aio_setup_vectored_rw(WRITE, kiocb);
+ ret = aio_setup_vectored_rw(WRITE, kiocb, compat);
if (ret)
break;
ret = -EINVAL;
@@ -1548,7 +1556,8 @@ static void aio_batch_free(struct hlist_head *batch_hash)
}

static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
- struct iocb *iocb, struct hlist_head *batch_hash)
+ struct iocb *iocb, struct hlist_head *batch_hash,
+ bool compat)
{
struct kiocb *req;
struct file *file;
@@ -1609,7 +1618,7 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
req->ki_left = req->ki_nbytes = iocb->aio_nbytes;
req->ki_opcode = iocb->aio_lio_opcode;

- ret = aio_setup_iocb(req);
+ ret = aio_setup_iocb(req, compat);

if (ret)
goto out_put_req;
@@ -1637,20 +1646,8 @@ out_put_req:
return ret;
}

-/* sys_io_submit:
- * Queue the nr iocbs pointed to by iocbpp for processing. Returns
- * the number of iocbs queued. May return -EINVAL if the aio_context
- * specified by ctx_id is invalid, if nr is < 0, if the iocb at
- * *iocbpp[0] is not properly initialized, if the operation specified
- * is invalid for the file descriptor in the iocb. May fail with
- * -EFAULT if any of the data structures point to invalid data. May
- * fail with -EBADF if the file descriptor specified in the first
- * iocb is invalid. May fail with -EAGAIN if insufficient resources
- * are available to queue any iocbs. Will return 0 if nr is 0. Will
- * fail with -ENOSYS if not implemented.
- */
-SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
- struct iocb __user * __user *, iocbpp)
+long do_io_submit(aio_context_t ctx_id, long nr,
+ struct iocb __user *__user * iocbpp, bool compat)
{
struct kioctx *ctx;
long ret = 0;
@@ -1687,7 +1684,7 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
break;
}

- ret = io_submit_one(ctx, user_iocb, &tmp, batch_hash);
+ ret = io_submit_one(ctx, user_iocb, &tmp, batch_hash, compat);
if (ret)
break;
}
@@ -1696,6 +1693,24 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
put_ioctx(ctx);
return i ? i : ret;
}
+
+/* sys_io_submit:
+ * Queue the nr iocbs pointed to by iocbpp for processing. Returns
+ * the number of iocbs queued. May return -EINVAL if the aio_context
+ * specified by ctx_id is invalid, if nr is < 0, if the iocb at
+ * *iocbpp[0] is not properly initialized, if the operation specified
+ * is invalid for the file descriptor in the iocb. May fail with
+ * -EFAULT if any of the data structures point to invalid data. May
+ * fail with -EBADF if the file descriptor specified in the first
+ * iocb is invalid. May fail with -EAGAIN if insufficient resources
+ * are available to queue any iocbs. Will return 0 if nr is 0. Will
+ * fail with -ENOSYS if not implemented.
+ */
+SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
+ struct iocb __user * __user *, iocbpp)
+{
+ return do_io_submit(ctx_id, nr, iocbpp, 0);
+}

/* lookup_kiocb
* Finds a given iocb for cancellation.
diff --git a/fs/compat.c b/fs/compat.c
index 00d90c2..efbcb31 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -567,6 +567,61 @@ out:
return ret;
}

+/* A write operation does a read from user space and vice versa */
+#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
+
+ssize_t compat_rw_copy_check_uvector(int type,
+ const struct compat_iovec __user *uiov32, unsigned long niov,
+ unsigned long fast_segs, struct iovec *fast_pointer,
+ struct iovec **ret_pointer)
+{
+ ssize_t tot_len = 0;
+ struct iovec *kiov = fast_pointer;
+
+ if (niov == 0)
+ goto out;
+ if (niov > UIO_MAXIOV) {
+ tot_len = -EINVAL;
+ goto out;
+ }
+ if (niov > fast_segs) {
+ kiov = kmalloc(niov*sizeof(struct iovec), GFP_KERNEL);
+ if (kiov == NULL) {
+ tot_len = -ENOMEM;
+ goto out;
+ }
+ }
+ *ret_pointer = kiov;
+
+ while (niov > 0) {
+ compat_uptr_t buf;
+ compat_size_t len;
+
+ if (get_user(len, &uiov32->iov_len) ||
+ get_user(buf, &uiov32->iov_base)) {
+ tot_len = -EFAULT;
+ goto out;
+ }
+ if (len < 0 || (tot_len + len < tot_len)) {
+ tot_len = -EINVAL;
+ goto out;
+ }
+ if (!access_ok(vrfy_dir(type), buf, len)) {
+ tot_len = -EFAULT;
+ goto out;
+ }
+ tot_len += len;
+ kiov->iov_base = compat_ptr(buf);
+ kiov->iov_len = (__kernel_size_t) len;
+ uiov32++;
+ kiov++;
+ niov--;
+ }
+
+out:
+ return tot_len;
+}
+
static inline long
copy_iocb(long nr, u32 __user *ptr32, struct iocb __user * __user *ptr64)
{
@@ -599,7 +654,7 @@ compat_sys_io_submit(aio_context_t ctx_id, int nr, u32 __user *iocb)
iocb64 = compat_alloc_user_space(nr * sizeof(*iocb64));
ret = copy_iocb(nr, iocb, iocb64);
if (!ret)
- ret = sys_io_submit(ctx_id, nr, iocb64);
+ ret = do_io_submit(ctx_id, nr, iocb64, 1);
return ret;
}

diff --git a/include/linux/aio.h b/include/linux/aio.h
index 811dbb3..54b6ef8 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -212,6 +212,8 @@ extern void kick_iocb(struct kiocb *iocb);
extern int aio_complete(struct kiocb *iocb, long res, long res2);
struct mm_struct;
extern void exit_aio(struct mm_struct *mm);
+extern long do_io_submit(aio_context_t ctx_id, long nr,
+ struct iocb __user *__user * iocbpp, bool compat);
#else
static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
static inline int aio_put_req(struct kiocb *iocb) { return 0; }
@@ -219,6 +221,9 @@ static inline void kick_iocb(struct kiocb *iocb) { }
static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
struct mm_struct;
static inline void exit_aio(struct mm_struct *mm) { }
+static inline long do_io_submit(aio_context_t ctx_id, long nr,
+ struct iocb __user * __user * iocbpp,
+ bool compat) { }
#endif /* CONFIG_AIO */

static inline struct kiocb *list_kiocb(struct list_head *h)
diff --git a/include/linux/compat.h b/include/linux/compat.h
index ef68119..8251f61 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -353,5 +353,9 @@ asmlinkage long compat_sys_newfstatat(unsigned int dfd, char __user * filename,
asmlinkage long compat_sys_openat(unsigned int dfd, const char __user *filename,
int flags, int mode);

+extern ssize_t compat_rw_copy_check_uvector(int type,
+ const struct compat_iovec __user *uiov32, unsigned long niov,
+ unsigned long fast_segs, struct iovec *fast_pointer,
+ struct iovec **ret_pointer);
#endif /* CONFIG_COMPAT */
#endif /* _LINUX_COMPAT_H */

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