Auto merge of #83619 - petrochenkov:nx, r=nagisa

bors · bors · commit cb0e0db641bb · 2021-03-28T21:36:27.000Z
linker: Use data execution prevention options by default when linker supports them

Do it in a centralized way in `link.rs` instead of individual target specs.
r? `@nagisa`
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -1651,6 +1651,10 @@ fn linker_with_args<'a, B: ArchiveBuilder<'a>>(
         cmd.add_eh_frame_header();
     }
 
+    // NO-OPT-OUT, OBJECT-FILES-NO, AUDIT-ORDER
+    // Make the binary compatible with data execution prevention schemes.
+    cmd.add_no_exec();
+
     // NO-OPT-OUT, OBJECT-FILES-NO
     // Avoid linking to dynamic libraries unless they satisfy some undefined symbols
     // at the point at which they are specified on the command line.
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -130,6 +130,7 @@ pub trait Linker {
     fn group_end(&mut self);
     fn linker_plugin_lto(&mut self);
     fn add_eh_frame_header(&mut self) {}
+    fn add_no_exec(&mut self) {}
     fn add_as_needed(&mut self) {}
     fn finalize(&mut self);
 }
@@ -643,6 +644,14 @@ impl<'a> Linker for GccLinker<'a> {
         self.linker_arg("--eh-frame-hdr");
     }
 
+    fn add_no_exec(&mut self) {
+        if self.sess.target.is_like_windows {
+            self.linker_arg("--nxcompat");
+        } else if self.sess.target.linker_is_gnu {
+            self.linker_arg("-znoexecstack");
+        }
+    }
+
     fn add_as_needed(&mut self) {
         if self.sess.target.linker_is_gnu {
             self.linker_arg("--as-needed");
@@ -885,6 +894,10 @@ impl<'a> Linker for MsvcLinker<'a> {
     fn linker_plugin_lto(&mut self) {
         // Do nothing
     }
+
+    fn add_no_exec(&mut self) {
+        self.cmd.arg("/NXCOMPAT");
+    }
 }
 
 pub struct EmLinker<'a> {
diff --git a/compiler/rustc_target/src/spec/dragonfly_base.rs b/compiler/rustc_target/src/spec/dragonfly_base.rs
@@ -1,23 +1,13 @@
-use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions};
+use crate::spec::{RelroLevel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut args = LinkArgs::new();
-    args.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // Always enable NX protection when it is available
-            "-Wl,-z,noexecstack".to_string(),
-        ],
-    );
-
     TargetOptions {
         os: "dragonfly".to_string(),
         dynamic_linking: true,
         executables: true,
         os_family: Some("unix".to_string()),
         linker_is_gnu: true,
         has_rpath: true,
-        pre_link_args: args,
         position_independent_executables: true,
         relro_level: RelroLevel::Full,
         dwarf_version: Some(2),
diff --git a/compiler/rustc_target/src/spec/freebsd_base.rs b/compiler/rustc_target/src/spec/freebsd_base.rs
@@ -1,23 +1,13 @@
-use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions};
+use crate::spec::{RelroLevel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut args = LinkArgs::new();
-    args.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // Always enable NX protection when it is available
-            "-Wl,-z,noexecstack".to_string(),
-        ],
-    );
-
     TargetOptions {
         os: "freebsd".to_string(),
         dynamic_linking: true,
         executables: true,
         os_family: Some("unix".to_string()),
         linker_is_gnu: true,
         has_rpath: true,
-        pre_link_args: args,
         position_independent_executables: true,
         eliminate_frame_pointer: false, // FIXME 43575
         relro_level: RelroLevel::Full,
diff --git a/compiler/rustc_target/src/spec/linux_base.rs b/compiler/rustc_target/src/spec/linux_base.rs
@@ -1,23 +1,13 @@
-use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions};
+use crate::spec::{RelroLevel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut args = LinkArgs::new();
-    args.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // Always enable NX protection when it is available
-            "-Wl,-z,noexecstack".to_string(),
-        ],
-    );
-
     TargetOptions {
         os: "linux".to_string(),
         dynamic_linking: true,
         executables: true,
         os_family: Some("unix".to_string()),
         linker_is_gnu: true,
         has_rpath: true,
-        pre_link_args: args,
         position_independent_executables: true,
         relro_level: RelroLevel::Full,
         has_elf_tls: true,
diff --git a/compiler/rustc_target/src/spec/linux_kernel_base.rs b/compiler/rustc_target/src/spec/linux_kernel_base.rs
@@ -1,11 +1,6 @@
-use crate::spec::{
-    LinkArgs, LinkerFlavor, PanicStrategy, RelocModel, RelroLevel, StackProbeType, TargetOptions,
-};
+use crate::spec::{PanicStrategy, RelocModel, RelroLevel, StackProbeType, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut pre_link_args = LinkArgs::new();
-    pre_link_args.insert(LinkerFlavor::Gcc, vec!["-Wl,-z,noexecstack".to_string()]);
-
     TargetOptions {
         env: "gnu".to_string(),
         disable_redzone: true,
@@ -17,7 +12,6 @@ pub fn opts() -> TargetOptions {
         needs_plt: true,
         relro_level: RelroLevel::Full,
         relocation_model: RelocModel::Static,
-        pre_link_args,
 
         ..Default::default()
     }
diff --git a/compiler/rustc_target/src/spec/msvc_base.rs b/compiler/rustc_target/src/spec/msvc_base.rs
@@ -5,13 +5,6 @@ pub fn opts() -> TargetOptions {
         // Suppress the verbose logo and authorship debugging output, which would needlessly
         // clog any log files.
         "/NOLOGO".to_string(),
-        // Tell the compiler that non-code sections can be marked as non-executable,
-        // including stack pages.
-        // UEFI is fully compatible to non-executable data pages.
-        // In fact, firmware might enforce this, so we better let the linker know about this,
-        // so it will fail if the compiler ever tries placing code on the stack
-        // (e.g., trampoline constructs and alike).
-        "/NXCOMPAT".to_string(),
     ];
     let mut pre_link_args = LinkArgs::new();
     pre_link_args.insert(LinkerFlavor::Msvc, pre_link_args_msvc.clone());
diff --git a/compiler/rustc_target/src/spec/openbsd_base.rs b/compiler/rustc_target/src/spec/openbsd_base.rs
@@ -1,15 +1,6 @@
-use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions};
+use crate::spec::{RelroLevel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut args = LinkArgs::new();
-    args.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // Always enable NX protection when it is available
-            "-Wl,-z,noexecstack".to_string(),
-        ],
-    );
-
     TargetOptions {
         os: "openbsd".to_string(),
         dynamic_linking: true,
@@ -18,7 +9,6 @@ pub fn opts() -> TargetOptions {
         linker_is_gnu: true,
         has_rpath: true,
         abi_return_struct_as_int: true,
-        pre_link_args: args,
         position_independent_executables: true,
         eliminate_frame_pointer: false, // FIXME 43575
         relro_level: RelroLevel::Full,
diff --git a/compiler/rustc_target/src/spec/redox_base.rs b/compiler/rustc_target/src/spec/redox_base.rs
@@ -1,15 +1,6 @@
-use crate::spec::{LinkArgs, LinkerFlavor, RelroLevel, TargetOptions};
+use crate::spec::{RelroLevel, TargetOptions};
 
 pub fn opts() -> TargetOptions {
-    let mut args = LinkArgs::new();
-    args.insert(
-        LinkerFlavor::Gcc,
-        vec![
-            // Always enable NX protection when it is available
-            "-Wl,-z,noexecstack".to_string(),
-        ],
-    );
-
     TargetOptions {
         os: "redox".to_string(),
         env: "relibc".to_string(),
@@ -18,7 +9,6 @@ pub fn opts() -> TargetOptions {
         os_family: Some("unix".to_string()),
         linker_is_gnu: true,
         has_rpath: true,
-        pre_link_args: args,
         position_independent_executables: true,
         relro_level: RelroLevel::Full,
         has_elf_tls: true,
diff --git a/compiler/rustc_target/src/spec/windows_gnu_base.rs b/compiler/rustc_target/src/spec/windows_gnu_base.rs
@@ -9,8 +9,6 @@ pub fn opts() -> TargetOptions {
             // Tell GCC to avoid linker plugins, because we are not bundling
             // them with Windows installer, and Rust does its own LTO anyways.
             "-fno-use-linker-plugin".to_string(),
-            // Always enable DEP (NX bit) when it is available
-            "-Wl,--nxcompat".to_string(),
             // Enable ASLR
             "-Wl,--dynamicbase".to_string(),
             // ASLR will rebase it anyway so leaving that option enabled only leads to confusion
diff --git a/compiler/rustc_target/src/spec/x86_64_fortanix_unknown_sgx.rs b/compiler/rustc_target/src/spec/x86_64_fortanix_unknown_sgx.rs
@@ -4,8 +4,6 @@ use super::{LinkerFlavor, LldFlavor, PanicStrategy, Target, TargetOptions};
 
 pub fn target() -> Target {
     const PRE_LINK_ARGS: &[&str] = &[
-        "-z",
-        "noexecstack",
         "-e",
         "elf_entry",
         "-Bstatic",
