Add wrapper for linux kernel module loading

- init_module and finit_module to load kernel modules
- delete_module to unload kernel modules

Author: bachp

src/kmod.rs

@@ -0,0 +1,90 @@
+//! Load and unload kernel modules.
+
+use libc;
+use std::os::unix::io::AsRawFd;
+use std::ffi::CStr;
+
+use errno::Errno;
+use Result;
+
+/// Loads an ELF image into kernel space, performs any necessary symbol relocations,
+/// initializes module parameters to values provided by the caller, and then runs the module's init function.
+/// This function requires privilege.
+///
+/// The module_image argument points to a buffer containing the binary image to be loaded.
+/// The module image should be a valid ELF image, built for the running kernel.
+///
+/// The param_values argument is a string containing space-delimited specifications of the values for module parameters.
+/// Each of the parameter specifications has the form:
+///
+/// `name[=value[,value...]]`
+///
+/// Example usage:
+///
+/// ```
+/// let mut f = File::open("mykernel.ko").unwrap();
+/// let mut contents: Vec<u8> = Vec::new();
+/// f.read_to_end(&mut contents).unwrap();
+/// init_module(&mut contents, &CString::new("").unwrap()).unwrap();
+/// ```
+///
+pub fn init_module(module_image: &[u8], param_values: &CStr) -> Result<()> {
+    let res = unsafe {
+        libc::syscall(
+            libc::SYS_init_module,
+            module_image.as_ptr(),
+            module_image.len(),
+            param_values.as_ptr(),
+        )
+    };
+
+    Errno::result(res).map(drop)
+}
+
+
+libc_bitflags!(
+    /// Flags used by the `finit_module` function.
+    pub struct ModuleInitFlags: libc::c_uint {
+        /// Ignore symbol version hashes.
+        MODULE_INIT_IGNORE_MODVERSIONS;
+        /// Ignore kernel version magic.
+        MODULE_INIT_IGNORE_VERMAGIC;
+    }
+);
+
+/// Loads a kernel module from a given file descriptor.
+///
+/// Example usage:
+///
+/// ```
+/// let f = File::open("mymod.ko").unwrap();
+/// finit_module(&f, &CString::new("").unwrap(), ModuleInitFlags::empty()).unwrap();
+/// ```
+///
+pub fn finit_module<T: AsRawFd>(fd: &T, param_values: &CStr, flags:ModuleInitFlags) -> Result<()> {
+    let res = unsafe { libc::syscall(libc::SYS_finit_module, fd.as_raw_fd(), param_values.as_ptr(), flags.bits()) };
+
+    Errno::result(res).map(drop)
+}
+
+libc_bitflags!(
+    /// Flags used by `delete_module`.
+    pub struct OFlags: libc::c_int {
+        O_NONBLOCK;
+        O_TRUNC;
+    }
+);
+
+/// Unloads the kernel module with the given name.
+///
+/// Example usage:
+///
+/// ```
+/// delete_module(&CString::new("mymod").unwrap(), OFlags::O_NONBLOCK).unwrap();
+/// ```
+///
+pub fn delete_module(name: &CStr, flags: OFlags) -> Result<()> {
+    let res = unsafe { libc::syscall(libc::SYS_delete_module, name.as_ptr(), flags.bits()) };
+
+    Errno::result(res).map(drop)
+}

src/lib.rs

@@ -43,6 +43,8 @@ pub mod fcntl;
           target_os = "openbsd"))]
 pub mod ifaddrs;
 #[cfg(any(target_os = "linux", target_os = "android"))]
+pub mod kmod;
+#[cfg(any(target_os = "linux", target_os = "android"))]
 pub mod mount;
 #[cfg(any(target_os = "dragonfly",
           target_os = "freebsd",