Clean up html on the website.

- Fixes some html validation issues.
- Fixes links on security basics blog post.
- Adds rel=noopener to links with target=_blank and adds a check to
  htmlproofer.
- Add favicon check to htmlproofer.

Fixes #3286
Fixes #3284

PiperOrigin-RevId: 321892602

1 files changed, 15 insertions, 8 deletions

diff --git a/website/blog/2019-11-18-security-basics.md b/website/blog/2019-11-18-security-basics.md
index fbdd511dd..76bbabc13 100644
--- a/website/blog/2019-11-18-security-basics.md
+++ b/website/blog/2019-11-18-security-basics.md
@@ -44,10 +44,10 @@ into it in the next section!
 
 # Design Principles
 
-gVisor was designed with some
-[common secure design principles](https://www.owasp.org/index.php/Security_by_Design_Principles)
-in mind: Defense-in-Depth, Principle of Least-Privilege, Attack Surface
-Reduction and Secure-by-Default[^1].
+gVisor was designed with some common
+[secure design](https://en.wikipedia.org/wiki/Secure_by_design) principles in
+mind: Defense-in-Depth, Principle of Least-Privilege, Attack Surface Reduction
+and Secure-by-Default[^1].
 
 In general, Design Principles outline good engineering practices, but in the
 case of security, they also can be thought of as a set of tactics. In a
@@ -282,16 +282,23 @@ stable.
 
 ## Notes
 
-[^1]: [https://www.owasp.org/index.php/Security_by_Design_Principles](https://www.owasp.org/index.php/Security_by_Design_Principles)
+[^1]: [https://en.wikipedia.org/wiki/Secure_by_design](https://en.wikipedia.org/wiki/Secure_by_design)
 [^2]: [https://gvisor.dev/docs/architecture_guide](https://gvisor.dev/docs/architecture_guide/)
 [^3]: [https://github.com/google/gvisor/blob/master/pkg/sentry/syscalls/linux/linux64_amd64.go](https://github.com/google/gvisor/blob/master/pkg/sentry/syscalls/syscalls.go)
-[^4]: Internally that is, it doesn't call to the Host OS to implement them, in
-    fact that is explicitly disallowed, more on that in the future.
+
+<!-- mdformat off(mdformat formats this into multiple lines) -->
+[^4]: Internally that is, it doesn't call to the Host OS to implement them, in fact that is explicitly disallowed, more on that in the future.
+<!-- mdformat on -->
+
 [^5]: [https://elixir.bootlin.com/linux/latest/source/arch/x86/entry/syscalls/syscall_64.tbl#L345](https://elixir.bootlin.com/linux/latest/source/arch/x86/entry/syscalls/syscall_64.tbl#L345)
 [^6]: [https://github.com/google/gvisor/tree/master/runsc/boot/filter](https://github.com/google/gvisor/tree/master/runsc/boot/filter)
 [^7]: [https://en.wikipedia.org/wiki/Dirty_COW](https://en.wikipedia.org/wiki/Dirty_COW)
 [^8]: [https://github.com/google/gvisor/blob/master/runsc/boot/config.go](https://github.com/google/gvisor/blob/master/runsc/boot/config.go)
-[^9]: [https://en.wikipedia.org/wiki/9P_(protocol)](https://en.wikipedia.org/wiki/9P_\(protocol\))
+
+<!-- mdformat off(mdformat breaks this url by escaping the parenthesis) -->
+[^9]: [https://en.wikipedia.org/wiki/9P_(protocol)](https://en.wikipedia.org/wiki/9P_(protocol))
+<!-- mdformat on -->
+
 [^10]: [https://gvisor.dev/docs/user_guide/networking/#network-passthrough](https://gvisor.dev/docs/user_guide/networking/#network-passthrough)
 [^11]: [https://github.com/google/gvisor/blob/c7e901f47a09eaac56bd4813227edff016fa6bff/pkg/sentry/platform/ptrace/subprocess.go#L390](https://github.com/google/gvisor/blob/c7e901f47a09eaac56bd4813227edff016fa6bff/pkg/sentry/platform/ptrace/subprocess.go#L390)
 [^12]: [https://github.com/google/gvisor/blob/c7e901f47a09eaac56bd4813227edff016fa6bff/pkg/sentry/platform/ring0/kernel_amd64.go#L182](https://github.com/google/gvisor/blob/c7e901f47a09eaac56bd4813227edff016fa6bff/pkg/sentry/platform/ring0/kernel_amd64.go#L182)