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macsyscalls

Glossary

Entitlement

A signed key/value pair embedded in a macOS Mach-O binary that grants its process access to gated kernel and framework APIs.

An entitlement is a key-value pair embedded in a macOS Mach-O binary's code signature that declares a capability the binary should have. The kernel and the framework layer both check entitlements when deciding whether to grant a privileged operation.

A typical entitlement plist embedded in a debugger binary looks like:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.security.cs.debugger</key>
    <true/>
    <key>com.apple.security.cs.disable-library-validation</key>
    <true/>
</dict>
</plist>

Entitlements come in three classes by who can sign them:

  • Public — anyone with a Developer ID can claim them (com.apple.security.cs.debugger, com.apple.security.cs.allow-jit, etc.). Documented in Apple's Hardened Runtime guide.
  • Restricted — granted on a case-by-case basis after application to Apple (com.apple.developer.endpoint-security.client, com.apple.developer.system-extension.install).
  • Apple-private — only Apple-signed binaries can carry them (com.apple.system-task-ports, com.apple.private.tcc.allow, hundreds of others).

AMFI is responsible for verifying that an entitlement was actually signed by a trusted authority. A binary cannot grant itself an entitlement by editing its plist — the signature would no longer validate.

For syscall work, the most relevant entitlement is com.apple.security.cs.debugger, which is the path Xcode uses to take a task port on a debug-allowed target.