Writing a normal image to the SD card works ok?

(In reply to Martin Bříza from comment #1)
> Writing a normal image to the SD card works ok?

nope, same error message

I'll check this on more computers. In case it works for me, I'll stop by in your cubicle.

Doesn't work in GNOME Disks either, the problem lies somewhere below in the stack, either in udisks/storage or even selinux.
Reassigning.

I find it unlikely you're using storaged in F26...

Thanks, I wasn't sure if we switched back or not. Sorry for using the wrong component. :)

(In reply to Martin Bříza from comment #4)
> Doesn't work in GNOME Disks either, the problem lies somewhere below in the
> stack, either in udisks/storage or even selinux.

Good guess! Here's what I've found out so far:

1. udisks2 is terminated with SIGTERM after processing the request to open a device for writing
2. it's udisks2 itself sending the SIGTERM
3. this all only happens with SELinux in enforcing mode

The OpenForRestore() method is using a bit special feature of DBus (and POSIX sockets in general) -- it passes an open file descriptor over the DBus (socket). So I guess SELinux has some special treatment for this?

So this is specific to an SD card accessed as an 'mmcblk' device, i.e. over the internal card reader. When I used and external card reader, which presents the card as a SATA/SCSI-like device (/dev/sdb), everything worked just fine. Also, when I created a loop device on top of the mmcblk device, everything worked fine on that loop device.

The difference is quite clear from the output of 'll -Z':

brw-rw----. 1 root disk system_u:object_r:fixed_disk_device_t:s0 8, 0 May 26 20:21 /dev/sdb

brw-rw----. 1 root disk system_u:object_r:fixed_disk_device_t:s0 7, 0 May 26 20:23 /dev/loop0

brw-rw----. 1 root disk system_u:object_r:removable_device_t:s0 179, 0 May 26 20:22 /dev/mmcblk0

The problem is clearly with the 'removable_device_t' label on the card being accessed over the mmc_block driver.

I just don't know yet, where the problematic definitions are as well as what defines labels on those devices. Just selinux-policy and udev, respectively, I guess?

Reassigning to selinux-policy as this is clearly a SELinux-related issue. I believe the policy needs an extra "rule" next to this one:

storage_raw_read_fixed_disk(udisks2_t)

which would enable the raw_read for removable_device_t.

selinux-policy-3.13.1-257.fc26 has been submitted as an update to Fedora 26. https://bodhi.fedoraproject.org/updates/FEDORA-2017-6a43388229

selinux-policy-3.13.1-257.fc26 has been pushed to the Fedora 26 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2017-6a43388229

selinux-policy-3.13.1-257.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.

I still have the same issue:

W@27747ms: Writing failed: "Message recipient disconnected from message bus without replying"

selinux-policy-3.13.1-257.fc26.noarch
mediawriter-4.1.0-1.fc26.x86_64

but when I disable selinux (setenforce 0), fmw works as expected. Reopening.

Lukas,

Could you set switch to permissive mode:
# setenforce 0

And then reproduce the scenario and attach output of: 
# ausearch -m AVC, USER_AVC -ts today 

THanks. 
Lukas.

Created attachment 1287287 [details]
ausearch -m AVC,USER_AVC -ts today

Also experienced currently on F27.

Works with a USB SD card writer; this error is thrown when using the laptop inbuilt SD card slot.

mediawriter-4.1.1-1.fc27.x86_64

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(In reply to Kevin R. Page from comment #16)
> Also experienced currently on F27.
> 
> Works with a USB SD card writer; this error is thrown when using the laptop
> inbuilt SD card slot.
> 
> mediawriter-4.1.1-1.fc27.x86_64

Same happened to me with mediawriter-4.1.4-1.fc28.x86_64. I'll let you know if this happens on F30 when I'll upgrade.