.Net Foundation Code Conversations, 15 Aug 2017

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From YouTube: The File API in IIS Administration API with Jimmy Campbell

Description

Jimmy Campbell shows how you can use the IIS Administration API to manipulate files on your servers running IIS, then digs into the code to show how they secured remote file administration in .NET Core.
Source code for this presentation: https://github.com/microsoft/iis_administration

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Hi, welcome to code conversations. today, we're continuing our conversation with.

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Jimmy campbell about is administration api. Yes, thanks for having me so today,.

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We're going to be talking about the iis administration api, like you said, and I.

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Want to take this opportunity to dive into the file api that we added to the.

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To the api to allow people to add it to content on their web servers,, maybe.

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Deploy websites, make sure everything is running fine, edit web.configs inline.

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It's allowing you to perform any file operation that you want on your web.

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Servers and now we have that exposed through this api cool, we'll go into that.

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So this is the api explorer tool that we talked about in our previous code. Conversations.

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So this is showing us what the file api is returning to us. So when.

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We go, we see, we have these root directories, here:, inetpub and c sites.

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So what do these mean?? Well, this api provides access to the filesystem on.

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Your iis machines, but it doesn't have complete control.

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It only has control over the directories that you say it can manipulate so for.

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Example, inet pub by default. It has read access on the system and this is the.

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Iis folder, so it makes sense that you want to be able to read folders or read.

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Content in this directory, so we see on our api explorer. We have read access to.

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Inet pub- and this is this- is important because it brings up some of the.

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Security stumbling points or security considerations we have when we develop.

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An api like this, so what does the code look like that allows us to constrain.

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Something so powerful, such as manipulation of files to specific.

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Directories so first, I want to give it a little demo of what the file api allows us to do.

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So you see, I actually switched over to another application and.

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We haven't showed this one yet in a code conversation., this is an.

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Angular 2 application written in typescript that.

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We're working on and this consumes the iis administration api.. You can see it's.

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Located at manage.iis.net it's in a central location, so anybody can access.

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It and what this does is this allows you to connect to an installation with api.

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That you have on an iis server. okay. and your calls are not made to us at manage.iis.net.

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Your calls are made directly to api, we're not in the middle, but.

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It'll provides a user interface for you to consume this api in a really easy to use. Way.

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Right, okay. so, like you talked about before these arrest, endpoints and here's.

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An example: this is an angular app, that's making those rest calls directly into.

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That api running on my server exactly so this is a so. This is the files view for.

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The ui, the angular 2 ui, and what we do, what we can do here is we can see all.

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The files for this website, so this is a website that I just made this morning.

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And what I'm going to do is I'm actually going to upload a dotnet new application.

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Into the folder for this website and then I'm going to browse it just to show.

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That this is what the file api allows us to do, or at least one of the things that.

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Allows has many capabilities, but this is one thing.

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So you see, I'm uploading the files to the angular 2 or using my api, and the application is giving us this.

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Nice little progress bar, so I was really happy to work on ramsevak yeah, so I've.

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Spent a lot of time on that thing. Actually, so I'm really happy with that.

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So we uploaded the files now I'm going to browse the website, just the standard.

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.Net new application, like I said, but this is what the api is, allowing us to.

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Do and in conjunction with the ui so now now that we've seen the file api in use.

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Kind of talk about what it provides us now, I want to jump into the code sure.

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That's what that's, what I'm going to go ahead and do ok, so the first part about.

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The filesystem api is realizing that we have a lot of power here there we can. We.

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Can mess things up if we manipulate some things, we don't want to touch. right.

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So, ultimately, how do we secure this thing and the way we do this in our code.

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Is one method and it's on the screen right now: that's get claims. So if you.

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Look in my appsettings.json.right here you'll see that I allow these two paths.

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To be manipulated, I allow these two paths manipulated by file api, and this is.

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Actually a dev configuration, so I'm glad I have this up because I actually want.

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To say, you should probably never expose, read and write to your whole system, but.

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I'm developing right now, so I specifically want to be able to touch my whole system.

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But in reality you probably want to limit it to something a folder. We.

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Specifically, have websites that's what the fit file api is touching. okay.. So we.

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Say we have directories that we want the api to be able to touch, and we have one.

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Method that says, if there's ever a physical path, that we are going to touch.

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In this api, is this an allowed directory in the configuration and do they have.

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Read or write access, if that's what they're trying to do., so this getclaims.

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Right here, so we pass a physical path, maybe,, maybe c:\inetpub\wwwroot, and we're.

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Going to reference the app settings, we have that loaded into memory, we're going.

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To check to see is that a full path, so this is the utility method we have right.

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Here it's going to do things like is: is this a non normalized path like? Is that.

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Dot dot in it, because there's a lot of weird things you are doing rational and.

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Also says make sure the environment variables are expanded if it's not a.

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Path, that's totally. Okay, we're not going to touch it. Look you don't have access.

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To it, so it's up to it's up to the consumers of this api here right in the.

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Application to make sure they pass it a good path. okay,. So this right here is going.

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To say whether or not you have the access to that path, so you get the.

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Claims. claims would be read or write so give it a path you get claims. That's the.

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Basis of all the security and now one step up from that, when you have the base.

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We have this file perm I'll, go into the interface the I file provider actually.

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The ifileprovider now this is abstracting all access to the file system.

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Now this is something I think is good to talk about. In a code conversation.

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Because one thing has software engineers that we try to do is.

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Program against the interface rather than implementation., this is a good.

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Example because, as you can see, we have these things ifileinfo, we have.

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Ifileprovider, which tracks the file system so we're not ever calling file.getfile or.

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Something like that in our code and it's not over the top, and it also allows us.

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To do things so it allows us to make sure our security is in check, because.

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Under the hood, it's calling down to get claims every time.. It allows us to make.

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Sure that if we want to extend the file system in some way in the future, right.

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For example, some physical path that doesn't exist on the physical file.

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System, but it's made up like maybe our application knows it. We can abstract.

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That in this ifileprovider interface and maybe getfile..., maybe getgile to.

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Cert colon slash, slash something returns a certificate as an abstract, as as a.

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File so that's kind of the beauty of what we get from programming against.

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Interface rather than implementation, so those are the two big parts that allow.

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Us to create powerful file system api, having a good security starting point.

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And then abstracting it all with this interface, the ifileprovider.

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You can see we have insulate implementation here. This is the guy.

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That's actually making sure any windows, authentication errors or anything. It's.

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Going to happen when it's touching, the file system is handled, but nobody else.

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Is ever going to care about the file system? This allowed us to be able to secure file system api., and it's also the kind of approach we're going to take one.

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Where, as we develop, certificates and stuff like that.

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cool.- and you mentioned before, this is all out on github right?, this is open. Source?.

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Absolutely., so this is the open source repository..., the iis.

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Administration api... I'll go to the github repository right here, as you can see.

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This is it, you can browse the source, file. Issue, make a suggestion. If you want.

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To start contributing,, I advise or... I welcome that.

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Start today and you could shape this product.

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cool. all right, thank you. thanks. So much. thanks for having me.