Documentation was already clear on this only stripping GPS tags.
But there are more potentially sensitive metadata tags (e.g. author
and possibly description) and the name alone suggests a broader effect.
Thus change the filter to strip all metadata except for colourspace info
and orientation (technically it strips everything and then readds
selected tags).
Explicitly stripping CommonIFD0 is needed since -all does not modify
IFD0 due to TIFF storing some actual image data there. CommonIFD0 then
strips a bunch of commonly used actual metadata tags from IFD0, to my
understanding leaving TIFF image data and custom metadata tags intact.
Alongside moving to certbot's nginx plugin, also use conf.d instead of
recreating the sites-{available,enabled} setup that Debian/Ubuntu uses.
Furthermore, also request a certificate for the media domain at the same
time since that's now required.
To save on bandwith and avoid OOMs with large files.
Ofc, this relies on the remote server
(a) sending a content-length header and
(b) being honest about the size.
Common fedi servers seem to provide the header and (b) at least raises
the required privilege of an malicious actor to a server infrastructure
admin of an explicitly allowed host.
A more complete defense which still works when faced with
a malicious server requires changes in upstream Finch;
see https://github.com/sneako/finch/issues/224
Even more than with user uploads, a same-domain proxy setup bears
significant security risks due to serving untrusted content under
the main domain space.
A risky setup like that should never be the default.
This actually was already intended before to eradict all future
path-traversal-style exploits and to fix issues with some
characters like akkoma#610 in 0b2ec0ccee. However, Dedupe and
AnonymizeFilename got mixed up. The latter only anonymises the name
in Content-Disposition headers GET parameters (with link_name),
_not_ the upload path.
Even without Dedupe, the upload path is prefixed by an UUID,
so it _should_ already be hard to guess for attackers. But now
we actually can be sure no path shenanigangs occur, uploads
reliably work and save some disk space.
While this makes the final path predictable, this prediction is
not exploitable. Insertion of a back-reference to the upload
itself requires pulling off a successfull preimage attack against
SHA-256, which is deemed infeasible for the foreseeable futures.
Dedupe was already included in the default list in config.exs
since 28cfb2c37a, but this will get overridde by whatever the
config generated by the "pleroma.instance gen" task chose.
Upload+delete tests running in parallel using Dedupe might be flaky, but
this was already true before and needs its own commit to fix eventually.
fixed up some grammer / wording. removed a setence and made wording more in line with what I could find in Admin-FE (especially wording of "rejecting" vs. dropping)
This vastly reduces idle CPU usage, which should generally be beneficial
for most small-to-medium sized instances.
Additionally update the documentation to specify how to override the vm.args
file for OTP installs
