[1/2] LUKS: better error message when creating too large files
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Message ID 20190721181508.28608-2-mlevitsk@redhat.com
State New
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Series
  • [1/2] LUKS: better error message when creating too large files
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Commit Message

Maxim Levitsky July 21, 2019, 6:15 p.m. UTC
Currently if you attampt to create too large file with luks you
get the following error message:

Formatting 'test.luks', fmt=luks size=17592186044416 key-secret=sec0
qemu-img: test.luks: Could not resize file: File too large

While for raw format the error message is
qemu-img: test.img: The image size is too large for file format 'raw'


The reason for this is that qemu-img checks for errono of the failure,
and presents the later error when it is -EFBIG

However crypto generic code 'swallows' the errno and replaces it
with -EIO.

As an attempt to make it better, we can make luks driver,
detect -EFBIG and in this case present a better error message,
which is what this patch does

The new error message is:

qemu-img: error creating test.luks: The requested file size is too large

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1534898
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 block/crypto.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

Comments

Daniel P. Berrangé July 22, 2019, 9:05 a.m. UTC | #1
On Sun, Jul 21, 2019 at 09:15:07PM +0300, Maxim Levitsky wrote:
> Currently if you attampt to create too large file with luks you
> get the following error message:
> 
> Formatting 'test.luks', fmt=luks size=17592186044416 key-secret=sec0
> qemu-img: test.luks: Could not resize file: File too large
> 
> While for raw format the error message is
> qemu-img: test.img: The image size is too large for file format 'raw'
> 
> 
> The reason for this is that qemu-img checks for errono of the failure,
> and presents the later error when it is -EFBIG
> 
> However crypto generic code 'swallows' the errno and replaces it
> with -EIO.
> 
> As an attempt to make it better, we can make luks driver,
> detect -EFBIG and in this case present a better error message,
> which is what this patch does
> 
> The new error message is:
> 
> qemu-img: error creating test.luks: The requested file size is too large
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1534898
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  block/crypto.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Regards,
Daniel
Maxim Levitsky Sept. 12, 2019, 10:44 p.m. UTC | #2
On Mon, 2019-07-22 at 10:05 +0100, Daniel P. Berrangé wrote:
> On Sun, Jul 21, 2019 at 09:15:07PM +0300, Maxim Levitsky wrote:
> > Currently if you attampt to create too large file with luks you
> > get the following error message:
> > 
> > Formatting 'test.luks', fmt=luks size=17592186044416 key-secret=sec0
> > qemu-img: test.luks: Could not resize file: File too large
> > 
> > While for raw format the error message is
> > qemu-img: test.img: The image size is too large for file format 'raw'
> > 
> > 
> > The reason for this is that qemu-img checks for errono of the failure,
> > and presents the later error when it is -EFBIG
> > 
> > However crypto generic code 'swallows' the errno and replaces it
> > with -EIO.
> > 
> > As an attempt to make it better, we can make luks driver,
> > detect -EFBIG and in this case present a better error message,
> > which is what this patch does
> > 
> > The new error message is:
> > 
> > qemu-img: error creating test.luks: The requested file size is too large
> > 
> > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1534898
> > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> > ---
> >  block/crypto.c | 25 +++++++++++++++++++++----
> >  1 file changed, 21 insertions(+), 4 deletions(-)
> 
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> 
> Regards,
> Daniel
Hi!

Do you think that we should merge this or, shall I close the bugreport
as WONTFIX?

Best regards,
	Maxim Levitsky

Patch
diff mbox series

diff --git a/block/crypto.c b/block/crypto.c
index 8237424ae6..73b1013fa1 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -102,18 +102,35 @@  static ssize_t block_crypto_init_func(QCryptoBlock *block,
                                       Error **errp)
 {
     struct BlockCryptoCreateData *data = opaque;
+    Error *local_error = NULL;
+    int ret;
 
     if (data->size > INT64_MAX || headerlen > INT64_MAX - data->size) {
-        error_setg(errp, "The requested file size is too large");
-        return -EFBIG;
+        ret = -EFBIG;
+        goto error;
     }
 
     /* User provided size should reflect amount of space made
      * available to the guest, so we must take account of that
      * which will be used by the crypto header
      */
-    return blk_truncate(data->blk, data->size + headerlen, PREALLOC_MODE_OFF,
-                        errp);
+    ret = blk_truncate(data->blk, data->size + headerlen, PREALLOC_MODE_OFF,
+                       &local_error);
+
+    if (ret >= 0) {
+        return ret;
+    }
+
+error:
+    if (ret == -EFBIG) {
+        /* Replace the error message with a better one */
+        error_free(local_error);
+        error_setg(errp, "The requested file size is too large");
+    } else {
+        error_propagate(errp, local_error);
+    }
+
+    return ret;
 }