From 27485f94b9cdda84f8330d09e4e2fe1c73a52ae4 Mon Sep 17 00:00:00 2001
From: trinity-1686a <trinity@deuxfleurs.fr>
Date: Mon, 7 Feb 2022 19:40:16 +0100
Subject: [PATCH] add length support to post policy

---
 src/api/s3_post_object.rs | 96 +++++++++++++++++++++++++++++++++------
 1 file changed, 81 insertions(+), 15 deletions(-)

diff --git a/src/api/s3_post_object.rs b/src/api/s3_post_object.rs
index 52229303..20b2e13c 100644
--- a/src/api/s3_post_object.rs
+++ b/src/api/s3_post_object.rs
@@ -2,9 +2,11 @@ use std::collections::HashMap;
 use std::convert::TryInto;
 use std::ops::RangeInclusive;
 use std::sync::Arc;
+use std::task::{Context, Poll};
 
+use bytes::Bytes;
 use chrono::{DateTime, Duration, Utc};
-use futures::StreamExt;
+use futures::{Stream, StreamExt};
 use hyper::header::{self, HeaderMap, HeaderName, HeaderValue};
 use hyper::{Body, Request, Response, StatusCode};
 use multer::{Constraints, Multipart, SizeLimit};
@@ -29,7 +31,7 @@ pub async fn handle_post_object(
 		.and_then(|ct| multer::parse_boundary(ct).ok())
 		.ok_or_bad_request("Counld not get multipart boundary")?;
 
-	// 16k seems plenty for a header. 5G is the max size of a single part, so it seemrs reasonable
+	// 16k seems plenty for a header. 5G is the max size of a single part, so it seems reasonable
 	// for a PostObject
 	let constraints = Constraints::new().size_limit(
 		SizeLimit::new()
@@ -119,9 +121,9 @@ pub async fn handle_post_object(
 
 		let conditions = decoded_policy.into_conditions()?;
 
-		for (key, value) in params.iter() {
-			let key = key.as_str();
-			if key.eq_ignore_ascii_case("content-type") {
+		for (param_key, value) in params.iter() {
+			let param_key = param_key.as_str();
+			if param_key.eq_ignore_ascii_case("content-type") {
 				for cond in &conditions.content_type {
 					let ok = match cond {
 						Operation::Equal(s) => value == s,
@@ -132,13 +134,29 @@ pub async fn handle_post_object(
 					if !ok {
 						return Err(Error::BadRequest(format!(
 							"Key '{}' has value not allowed in policy",
-							key
+							param_key
+						)));
+					}
+				}
+			} else if param_key == "key" {
+				let conds = conditions.params.get("key").ok_or_else(|| {
+					Error::BadRequest(format!("Key '{}' is not allowed in policy", param_key))
+				})?;
+				for cond in conds {
+					let ok = match cond {
+						Operation::Equal(s) => s == &key,
+						Operation::StartsWith(s) => key.starts_with(s),
+					};
+					if !ok {
+						return Err(Error::BadRequest(format!(
+							"Key '{}' has value not allowed in policy",
+							param_key
 						)));
 					}
 				}
 			} else {
-				let conds = conditions.params.get(key).ok_or_else(|| {
-					Error::BadRequest(format!("Key '{}' is not allowed in policy", key))
+				let conds = conditions.params.get(param_key).ok_or_else(|| {
+					Error::BadRequest(format!("Key '{}' is not allowed in policy", param_key))
 				})?;
 				for cond in conds {
 					let ok = match cond {
@@ -148,16 +166,13 @@ pub async fn handle_post_object(
 					if !ok {
 						return Err(Error::BadRequest(format!(
 							"Key '{}' has value not allowed in policy",
-							key
+							param_key
 						)));
 					}
 				}
 			}
 		}
 
-		// TODO validate policy against request
-		// unsafe to merge until implemented
-
 		let content_type = field
 			.content_type()
 			.map(AsRef::as_ref)
@@ -169,10 +184,11 @@ pub async fn handle_post_object(
 		params.append(header::CONTENT_TYPE, content_type);
 		let headers = get_headers(&params)?;
 
+		let stream = field.map(|r| r.map_err(Into::into));
 		let res = save_stream(
 			garage,
 			headers,
-			field.map(|r| r.map_err(Into::into)),
+			StreamLimiter::new(stream, conditions.content_length),
 			bucket_id,
 			&key,
 			None,
@@ -183,9 +199,10 @@ pub async fn handle_post_object(
 		let resp = if let Some(target) = params
 			.get("success_action_redirect")
 			.and_then(|h| h.to_str().ok())
+			.and_then(|u| url::Url::parse(u).ok())
+			.filter(|u| u.scheme() == "https" || u.scheme() == "http")
 		{
-			// TODO should validate it's a valid url
-			let target = target.to_owned();
+			let target = target.to_string();
 			Response::builder()
 				.status(StatusCode::SEE_OTHER)
 				.header(header::LOCATION, target.clone())
@@ -309,3 +326,52 @@ enum Operation {
 	Equal(String),
 	StartsWith(String),
 }
+
+struct StreamLimiter<T> {
+	inner: T,
+	length: RangeInclusive<u64>,
+	read: u64,
+}
+
+impl<T> StreamLimiter<T> {
+	fn new(stream: T, length: RangeInclusive<u64>) -> Self {
+		StreamLimiter {
+			inner: stream,
+			length,
+			read: 0,
+		}
+	}
+}
+
+impl<T> Stream for StreamLimiter<T>
+where
+	T: Stream<Item = Result<Bytes, Error>> + Unpin,
+{
+	type Item = Result<Bytes, Error>;
+	fn poll_next(
+		mut self: std::pin::Pin<&mut Self>,
+		ctx: &mut Context<'_>,
+	) -> Poll<Option<Self::Item>> {
+		let res = std::pin::Pin::new(&mut self.inner).poll_next(ctx);
+		match &res {
+			Poll::Ready(Some(Ok(bytes))) => {
+				self.read += bytes.len() as u64;
+				// optimization to fail early when we know before the end it's too long
+				if self.length.end() < &self.read {
+					return Poll::Ready(Some(Err(Error::BadRequest(
+						"File size does not match policy".to_owned(),
+					))));
+				}
+			}
+			Poll::Ready(None) => {
+				if !self.length.contains(&self.read) {
+					return Poll::Ready(Some(Err(Error::BadRequest(
+						"File size does not match policy".to_owned(),
+					))));
+				}
+			}
+			_ => {}
+		}
+		res
+	}
+}