git-annex/doc/special_remotes/web.mdwn

git-annex can use the WWW as a special remote, downloading urls to files.
See [[tips/using_the_web_as_a_special_remote]] for usage examples.

## notes

Currently git-annex only supports downloading content from the web; 
it cannot upload to it or remove content.

This special remote uses urls on the web as the source for content.
git-annex can also download content from a normal git remote, accessible by
http.
documentation for using the web 2011-07-01 20:01:26 +00:00			`git-annex can use the WWW as a special remote, downloading urls to files.`
wiki updates 2011-11-08 16:16:02 +00:00			`See [[tips/using_the_web_as_a_special_remote]] for usage examples.`
documentation for using the web 2011-07-01 20:01:26 +00:00
			`## notes`

			`Currently git-annex only supports downloading content from the web;`
			`it cannot upload to it or remove content.`
Added support for getting content from git remotes using http (and https). 2011-08-17 01:12:48 +00:00
limit url downloads to whitelisted schemes Security fix! Allowing any schemes, particularly file: and possibly others like scp: allowed file exfiltration by anyone who had write access to the git repository, since they could add an annexed file using such an url, or using an url that redirected to such an url, and wait for the victim to get it into their repository and send them a copy. * Added annex.security.allowed-url-schemes setting, which defaults to only allowing http and https URLs. Note especially that file:/ is no longer enabled by default. * Removed annex.web-download-command, since its interface does not allow supporting annex.security.allowed-url-schemes across redirects. If you used this setting, you may want to instead use annex.web-options to pass options to curl. With annex.web-download-command removed, nearly all url accesses in git-annex are made via Utility.Url via http-client or curl. http-client only supports http and https, so no problem there. (Disabling one and not the other is not implemented.) Used curl --proto to limit the allowed url schemes. Note that this will cause git annex fsck --from web to mark files using a disallowed url scheme as not being present in the web. That seems acceptable; fsck --from web also does that when a web server is not available. youtube-dl already disabled file: itself (probably for similar reasons). The scheme check was also added to youtube-dl urls for completeness, although that check won't catch any redirects it might follow. But youtube-dl goes off and does its own thing with other protocols anyway, so that's fine. Special remotes that support other domain-specific url schemes are not affected by this change. In the bittorrent remote, aria2c can still download magnet: links. The download of the .torrent file is otherwise now limited by annex.security.allowed-url-schemes. This does not address any external special remotes that might download an url themselves. Current thinking is all external special remotes will need to be audited for this problem, although many of them will use http libraries that only support http and not curl's menagarie. The related problem of accessing private localhost and LAN urls is not addressed by this commit. This commit was sponsored by Brett Eisenberg on Patreon. 2018-06-15 20:52:24 +00:00			`This special remote uses urls on the web as the source for content.`
Added support for getting content from git remotes using http (and https). 2011-08-17 01:12:48 +00:00			`git-annex can also download content from a normal git remote, accessible by`
			`http.`