Make modinfo work properly (fixes #80)

Author: geofft

hello-world/src/lib.rs

@@ -30,7 +30,7 @@ impl Drop for HelloWorldModule {
 
 linux_kernel_module::kernel_module!(
     HelloWorldModule,
-    author: "Fish in a Barrel Contributors",
-    description: "An extremely simple kernel module",
-    license: "GPL"
+    author: b"Fish in a Barrel Contributors",
+    description: b"An extremely simple kernel module",
+    license: b"GPL"
 );

src/lib.rs

@@ -36,9 +36,9 @@ pub use crate::types::{CStr, Mode};
 ///
 /// linux_kernel_module::kernel_module!(
 ///     MyKernelModule,
-///     author: "Fish in a Barrel Contributors",
-///     description: "My very own kernel module!",
-///     license: "GPL"
+///     author: b"Fish in a Barrel Contributors",
+///     description: b"My very own kernel module!",
+///     license: b"GPL"
 /// );
 #[macro_export]
 macro_rules! kernel_module {
@@ -72,13 +72,43 @@ macro_rules! kernel_module {
         )*
     };
 
-    (@attribute $name:ident, $value:expr) => {
+    // TODO: The modinfo attributes below depend on the compiler placing
+    // the variables in order in the .modinfo section, so that you end up
+    // with b"key=value\0" in order in the section. This is a reasonably
+    // standard trick in C, but I'm not sure that rustc guarantees it.
+    //
+    // Ideally we'd be able to use concat_bytes! + stringify_bytes! +
+    // some way of turning a string literal (or at least a string
+    // literal token) into a bytes literal, and get a single static
+    // [u8; * N] with the whole thing, but those don't really exist yet.
+    // Most of the alternatives (e.g. .as_bytes() as a const fn) give
+    // you a pointer, not an array, which isn't right.
+
+    (@attribute author, $value:expr) => {
+        #[link_section = ".modinfo"]
+        pub static AUTHOR_KEY: [u8; 7] = *b"author=";
+        #[link_section = ".modinfo"]
+        pub static AUTHOR_VALUE: [u8; $value.len()] = *$value;
+        #[link_section = ".modinfo"]
+        pub static AUTHOR_NUL: [u8; 1] = *b"\0";
+    };
+
+    (@attribute description, $value:expr) => {
+        #[link_section = ".modinfo"]
+        pub static DESCRIPTION_KEY: [u8; 12] = *b"description=";
+        #[link_section = ".modinfo"]
+        pub static DESCRIPTION_VALUE: [u8; $value.len()] = *$value;
+        #[link_section = ".modinfo"]
+        pub static DESCRIPTION_NUL: [u8; 1] = *b"\0";
+    };
+
+    (@attribute license, $value:expr) => {
+        #[link_section = ".modinfo"]
+        pub static LICENSE_KEY: [u8; 8] = *b"license=";
+        #[link_section = ".modinfo"]
+        pub static LICENSE_VALUE: [u8; $value.len()] = *$value;
         #[link_section = ".modinfo"]
-        #[allow(non_upper_case_globals)]
-        // TODO: Generate a name the same way the kernel's `__MODULE_INFO` does.
-        // TODO: This needs to be a `[u8; _]`, since the kernel defines this as a  `const char []`.
-        // See https://github.com/rust-lang/rfcs/pull/2545
-        pub static $name: &'static [u8] = concat!(stringify!($name), "=", $value, '\0').as_bytes();
+        pub static LICENSE_NUL: [u8; 1] = *b"\0";
     };
 }
 

tests/chrdev-region-allocation/src/lib.rs

@@ -20,7 +20,7 @@ impl linux_kernel_module::KernelModule for ChrdevRegionAllocationTestModule {
 
 linux_kernel_module::kernel_module!(
     ChrdevRegionAllocationTestModule,
-    author: "Fish in a Barrel Contributors",
-    description: "A module for testing character device region allocation",
-    license: "GPL"
+    author: b"Fish in a Barrel Contributors",
+    description: b"A module for testing character device region allocation",
+    license: b"GPL"
 );

tests/chrdev/src/lib.rs

@@ -124,7 +124,7 @@ impl linux_kernel_module::KernelModule for ChrdevTestModule {
 
 linux_kernel_module::kernel_module!(
     ChrdevTestModule,
-    author: "Fish in a Barrel Contributors",
-    description: "A module for testing character devices",
-    license: "GPL"
+    author: b"Fish in a Barrel Contributors",
+    description: b"A module for testing character devices",
+    license: b"GPL"
 );

tests/filesystem/src/lib.rs

@@ -27,7 +27,7 @@ impl linux_kernel_module::KernelModule for TestFSModule {
 
 linux_kernel_module::kernel_module!(
     TestFSModule,
-    author: "Fish in a Barrel Contributors",
-    description: "A module for testing filesystem::register",
-    license: "GPL"
+    author: b"Fish in a Barrel Contributors",
+    description: b"A module for testing filesystem::register",
+    license: b"GPL"
 );

tests/modinfo/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "modinfo-tests"
+version = "0.1.0"
+authors = ["Alex Gaynor <alex.gaynor@gmail.com>", "Geoffrey Thomas <geofft@ldpreload.com>"]
+edition = "2018"
+
+[lib]
+crate-type = ["staticlib"]
+test = false
+
+[features]
+default = ["linux-kernel-module"]
+
+[dependencies]
+linux-kernel-module = { path = "../..", optional = true }
+
+[dev-dependencies]
+kernel-module-testlib = { path = "../../testlib" }

tests/modinfo/src/lib.rs

@@ -0,0 +1,18 @@
+#![no_std]
+
+use linux_kernel_module;
+
+struct ModinfoTestModule;
+
+impl linux_kernel_module::KernelModule for ModinfoTestModule {
+    fn init() -> linux_kernel_module::KernelResult<Self> {
+        Ok(ModinfoTestModule)
+    }
+}
+
+linux_kernel_module::kernel_module!(
+    ModinfoTestModule,
+    author: b"Fish in a Barrel Contributors",
+    description: b"Empty module for testing modinfo",
+    license: b"GPL"
+);

tests/modinfo/tests/tests.rs

@@ -0,0 +1,38 @@
+use std::env;
+use std::fs;
+use std::path::Path;
+use std::process::Command;
+
+use kernel_module_testlib::with_kernel_module;
+
+#[test]
+fn test_modinfo() {
+    let module = env::var("KERNEL_MODULE").unwrap();
+
+    for (key, value) in &[
+        ("author", "Fish in a Barrel Contributors"),
+        ("description", "Empty module for testing modinfo"),
+        ("license", "GPL"),
+    ] {
+        let modinfo = Command::new("modinfo")
+            .arg("-F")
+            .arg(key)
+            .arg(&module)
+            .output()
+            .unwrap();
+        assert!(modinfo.status.success());
+        assert_eq!(&std::str::from_utf8(&modinfo.stdout).unwrap().trim(), value);
+    }
+}
+
+#[test]
+fn test_no_proprietary_taint() {
+    let module = env::var("KERNEL_MODULE").unwrap();
+    let module_name = Path::new(&module).file_stem().unwrap();
+    let sysfs_path = Path::new("/sys/module").join(module_name).join("taint");
+
+    with_kernel_module(|| {
+        let taints = fs::read_to_string(&sysfs_path).unwrap();
+        assert!(!taints.contains("P"));
+    });
+}

tests/printk/src/lib.rs

@@ -16,7 +16,7 @@ impl linux_kernel_module::KernelModule for PrintkTestModule {
 
 linux_kernel_module::kernel_module!(
     PrintkTestModule,
-    author: "Fish in a Barrel Contributors",
-    description: "A module for testing println!()",
-    license: "GPL"
+    author: b"Fish in a Barrel Contributors",
+    description: b"A module for testing println!()",
+    license: b"GPL"
 );

tests/random/src/lib.rs

@@ -44,7 +44,7 @@ impl linux_kernel_module::KernelModule for RandomTestModule {
 
 linux_kernel_module::kernel_module!(
     RandomTestModule,
-    author: "Fish in a Barrel Contributors",
-    description: "A module for testing the CSPRNG",
-    license: "GPL"
+    author: b"Fish in a Barrel Contributors",
+    description: b"A module for testing the CSPRNG",
+    license: b"GPL"
 );