Add HMAC/IP support for different remote IP's through proxies & Cloud… #49
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| if (isset($this->server["HTTP_X_FORWARDED_FOR"]) && filter_var($this->server["HTTP_X_FORWARDED_FOR"], FILTER_VALIDATE_IP)) | ||
| { | ||
| return $this->server["HTTP_X_FORWARDED_FOR"]; | ||
| } |
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Attackers can lie about X-Forwarded-For. This should be guarded by a configuration setting.
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What would you suggest? A configuration setting as in hmac_ip_allow_x_forwarded_for? Or something more general that would include both this option as well as CloudFlare for example?
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Yes, a configuration setting would be a good idea. Let people opt into this behavior.
| { | ||
| if (isset($this->server["HTTP_CF_CONNECTING_IP"]) && filter_var($this->server["HTTP_CF_CONNECTING_IP"], FILTER_VALIDATE_IP)) | ||
| { | ||
| return $this->server["HTTP_CF_CONNECTING_IP"]; |
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What if an attacker specifies a fake header here after discovering the server's real IP?
What if an attacker specifies this header for a non-CloudFlare IP?
Etc.
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Would you suggest validating against the REMOTE_ADDR to the CloudFlare IP ranges? https://www.cloudflare.com/ips/
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Yes, and this can be hard-coded. We can update it in the future if their list of IPs widens.
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@paragonie-security I've thought about your suggestion and played around a bit but I think there's several approaches that I wanted to check with you first. Especially for the IP filtering for CloudFlare, there's multiple options:
or
in that case there's also two options:
Could you share with me your preferences? |
The library's default is to have the HMAC IP check enabled. This gives issues with sites that run through CloudFlare as the remote IP that CloudFlare connects from is different through requests. Thus this could result in an invalid request already if you have a page open for 2 minutes.
The added functionality adds support for the CloudFlare connecting IP and other commonly used proxy methods. With these changes you can continue to use the HMAC check through CloudFlare/proxies.