[libpas] Implement primary support for MTE but disabled

[Achierius]

86ccfc6

[libpas] Implement primary support for MTE but disabled
https://bugs.webkit.org/show_bug.cgi?id=299488
rdar://161273712

Reviewed by Daniel Liu

As announced on September 9th, the SoCs used in the next generation of
iPhones will include support for ARM'S Memory Tagging Extension
functionality. As part of Apple's MIE (Memory Integrity Enforcement)
feature, libpas should thus implement support for MTE and related
memory-safety functionality to ensure that WebKit is up to par with the
new memory safety standards set by the rest of the system.

In particular, this patch ensures that when possible we allocate memory
with backing MTE tag pages and tag allocations made within them prior to
returning allocation memory to the caller. Not all memory can be tagged
this way: in particular, objects >= 32K and objects which may be
referenced via compact pointers cannot be MTE tagged. There are other
exceptions as well, depending on process/object-type/platform.
It also implements a variety of hardening strategies to further
strengthen the feature and prevent certain well-known kinds of attacks.

To begin with, we will land this feature disabled behind
PAS_USE_OPENSOURCE_MTE. A later patch will enable it in stages.

Canonical link: https://commits.webkit.org/301336@main

96ceae2

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		⏳ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash c50fd4f)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	❌ 🛠 ios	❌ 🛠 mac	❌ 🛠 wpe	❌ 🛠 win	❌ 🛠 ios-apple
✅ 🧪 bindings	❌ 🛠 ios-sim	❌ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2	❌ 🧪 win-tests	⏳ 🛠 mac-apple
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	❌ 🧪 api-mac	❌ 🧪 api-wpe		❌ 🛠 vision-apple
✅ 🧪 webkitpy	❌ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	❌ 🛠 wpe-cairo
❌ 🛠 🧪 jsc	❌ 🧪 api-ios	❌ 🧪 mac-wk2	❌ 🛠 gtk
❌ 🛠 🧪 jsc-arm64	❌ 🛠 vision	❌ 🧪 mac-AS-debug-wk2	❌ 🧪 gtk-wk2
	❌ 🛠 vision-sim	❌ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
	⏳ 🧪 vision-wk2	❌ 🧪 mac-intel-wk2	❌ 🛠 playstation
	❌ 🛠 tv	❌ 🛠 mac-safer-cpp	❌ 🛠 jsc-armv7
	❌ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	❌ 🛠 watch
	❌ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash b72d9b4)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	❌ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	❌ 🧪 win-tests	❌ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	❌ 🧪 api-wpe		❌ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	❌ 🛠 jsc-armv7
	✅ 🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash ee954d3)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	⏳ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	💥 🧪 win-tests	⏳ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		⏳ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[danlliu]

r=me

[webkit-early-warning-system]

EWS run on previous version of this PR (hash ef56726)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	❌ 🛠 ios	❌ 🛠 mac	❌ 🛠 wpe	⏳ 🛠 win	❌ 🛠 ios-apple
✅ 🧪 bindings	❌ 🛠 ios-sim	🛠 mac-AS-debug	❌ 🧪 wpe-wk2	⏳ 🧪 win-tests	❌ 🛠 mac-apple
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	❌ 🧪 api-mac	❌ 🧪 api-wpe		❌ 🛠 vision-apple
✅ 🧪 webkitpy	❌ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	❌ 🛠 wpe-cairo
❌ 🛠 🧪 jsc	❌ 🧪 api-ios	❌ 🧪 mac-wk2	❌ 🛠 gtk
❌ 🛠 🧪 jsc-arm64	❌ 🛠 vision	🧪 mac-AS-debug-wk2	❌ 🧪 gtk-wk2
	❌ 🛠 vision-sim	❌ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
	⏳ 🧪 vision-wk2	❌ 🧪 mac-intel-wk2	❌ 🛠 playstation
	🛠 tv	🛠 mac-safer-cpp	❌ 🛠 jsc-armv7
	🛠 tv-sim		❌ 🧪 jsc-armv7-tests
	🛠 watch
	🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 96ceae2)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		⏳ 🛠 vision-apple
✅ 🧪 webkitpy	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp	✅ 🛠 jsc-armv7
	✅ 🛠 tv-sim		✅ 🧪 jsc-armv7-tests
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 301336@main (86ccfc6): https://commits.webkit.org/301336@main

Reviewed commits have been landed. Closing PR #51952 and removing active labels.