Merge #949

949: ptrace support for BSDs r=Susurrus a=xd009642

This PR adds support to the ptrace API for BSDs to close #947. It also adds a read and write method for reading and writing to a traced processes memory. The ptrace API created for linux offers this via a deprecated function so I added this so they can be feature equivalent without replicating a deprecated part of the API.

Due to the differences in ptrace on BSD and linux I've made a ptrace module to keep things readable.

Still to do - revert travis config to remove my feature branch and update the changelog. 

Co-authored-by: xd009642 <danielmckenna93@gmail.com>

CHANGELOG.md

@@ -25,6 +25,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#956](https://github.com/nix-rust/nix/pull/956))
 - Added a `fchownat` wrapper.
   ([#955](https://github.com/nix-rust/nix/pull/955))
+- Added support for `ptrace` on BSD operating systems ([#949](https://github.com/nix-rust/nix/pull/949))
+- Added `ptrace` functions for reads and writes to tracee memory and ptrace kill 
+  ([#949](https://github.com/nix-rust/nix/pull/949))
 
 ### Changed
 - Increased required Rust version to 1.22.1/

src/sys/mod.rs

@@ -38,7 +38,13 @@ pub mod mman;
 
 pub mod pthread;
 
-#[cfg(any(target_os = "android", target_os = "linux"))]
+#[cfg(any(target_os = "android",
+          target_os = "dragonfly",
+          target_os = "freebsd",
+          target_os = "linux",
+          target_os = "macos",
+          target_os = "netbsd",
+          target_os = "openbsd"))]
 pub mod ptrace;
 
 #[cfg(target_os = "linux")]

src/sys/ptrace/bsd.rs

@@ -0,0 +1,170 @@
+use errno::Errno;
+use libc::{self, c_int};
+use std::ptr;
+use sys::signal::Signal;
+use unistd::Pid;
+use Result;
+
+pub type RequestType = c_int;
+
+cfg_if! {
+    if #[cfg(any(target_os = "dragonfly", 
+                 target_os = "freebsd", 
+                 target_os = "macos",
+                 target_os = "openbsd"))] {
+        #[doc(hidden)]
+        pub type AddressType = *mut ::libc::c_char;
+    } else {
+        #[doc(hidden)]
+        pub type AddressType = *mut ::libc::c_void;
+    }
+}
+
+libc_enum! {
+    #[repr(i32)]
+    /// Ptrace Request enum defining the action to be taken.
+    pub enum Request {
+        PT_TRACE_ME,
+        PT_READ_I,
+        PT_READ_D,
+        #[cfg(target_os = "macos")]
+        PT_READ_U,
+        PT_WRITE_I,
+        PT_WRITE_D,
+        #[cfg(target_os = "macos")]
+        PT_WRITE_U,
+        PT_CONTINUE,
+        PT_KILL,
+        #[cfg(any(any(target_os = "dragonfly",
+                  target_os = "freebsd",
+                  target_os = "macos"),
+                  all(target_os = "openbsd", target_arch = "x86_64"),
+                  all(target_os = "netbsd", any(target_arch = "x86_64",
+                                                target_arch = "powerpc"))))]
+        PT_STEP,
+        PT_ATTACH,
+        PT_DETACH,
+        #[cfg(target_os = "macos")]
+        PT_SIGEXC,
+        #[cfg(target_os = "macos")]
+        PT_THUPDATE,
+        #[cfg(target_os = "macos")]
+        PT_ATTACHEXC
+    }
+}
+
+unsafe fn ptrace_other(
+    request: Request,
+    pid: Pid,
+    addr: AddressType,
+    data: c_int,
+) -> Result<c_int> {
+    Errno::result(libc::ptrace(
+        request as RequestType,
+        libc::pid_t::from(pid),
+        addr,
+        data,
+    )).map(|_| 0)
+}
+
+/// Sets the process as traceable, as with `ptrace(PT_TRACEME, ...)`
+///
+/// Indicates that this process is to be traced by its parent.
+/// This is the only ptrace request to be issued by the tracee.
+pub fn traceme() -> Result<()> {
+    unsafe { ptrace_other(Request::PT_TRACE_ME, Pid::from_raw(0), ptr::null_mut(), 0).map(|_| ()) }
+}
+
+/// Attach to a running process, as with `ptrace(PT_ATTACH, ...)`
+///
+/// Attaches to the process specified in pid, making it a tracee of the calling process.
+pub fn attach(pid: Pid) -> Result<()> {
+    unsafe { ptrace_other(Request::PT_ATTACH, pid, ptr::null_mut(), 0).map(|_| ()) }
+}
+
+/// Detaches the current running process, as with `ptrace(PT_DETACH, ...)`
+///
+/// Detaches from the process specified in pid allowing it to run freely
+pub fn detach(pid: Pid) -> Result<()> {
+    unsafe { ptrace_other(Request::PT_DETACH, pid, ptr::null_mut(), 0).map(|_| ()) }
+}
+
+/// Restart the stopped tracee process, as with `ptrace(PTRACE_CONT, ...)`
+///
+/// Continues the execution of the process with PID `pid`, optionally
+/// delivering a signal specified by `sig`.
+pub fn cont<T: Into<Option<Signal>>>(pid: Pid, sig: T) -> Result<()> {
+    let data = match sig.into() {
+        Some(s) => s as c_int,
+        None => 0,
+    };
+    unsafe {
+        // Ignore the useless return value
+        ptrace_other(Request::PT_CONTINUE, pid, 1 as AddressType, data).map(|_| ())
+    }
+}
+
+/// Issues a kill request as with `ptrace(PT_KILL, ...)`
+///
+/// This request is equivalent to `ptrace(PT_CONTINUE, ..., SIGKILL);` 
+pub fn kill(pid: Pid) -> Result<()> {
+    unsafe {
+        ptrace_other(Request::PT_KILL, pid, 0 as AddressType, 0).map(|_| ())
+    }
+}
+
+/// Move the stopped tracee process forward by a single step as with
+/// `ptrace(PT_STEP, ...)`
+///
+/// Advances the execution of the process with PID `pid` by a single step optionally delivering a
+/// signal specified by `sig`.
+///
+/// # Example
+/// ```rust
+/// extern crate nix;
+/// use nix::sys::ptrace::step;
+/// use nix::unistd::Pid;
+/// use nix::sys::signal::Signal;
+/// use nix::sys::wait::*;
+/// fn main() {
+///     // If a process changes state to the stopped state because of a SIGUSR1
+///     // signal, this will step the process forward and forward the user
+///     // signal to the stopped process
+///     match waitpid(Pid::from_raw(-1), None) {
+///         Ok(WaitStatus::Stopped(pid, Signal::SIGUSR1)) => {
+///             let _ = step(pid, Signal::SIGUSR1);
+///         }
+///         _ => {},
+///     }
+/// }
+/// ```
+#[cfg(
+    any(
+        any(target_os = "dragonfly", target_os = "freebsd", target_os = "macos"),
+        all(target_os = "openbsd", target_arch = "x86_64"),
+        all(target_os = "netbsd",
+            any(target_arch = "x86_64", target_arch = "powerpc")
+        )
+    )
+)]
+pub fn step<T: Into<Option<Signal>>>(pid: Pid, sig: T) -> Result<()> {
+    let data = match sig.into() {
+        Some(s) => s as c_int,
+        None => 0,
+    };
+    unsafe { ptrace_other(Request::PT_STEP, pid, ptr::null_mut(), data).map(|_| ()) }
+}
+
+/// Reads a word from a processes memory at the given address
+pub fn read(pid: Pid, addr: AddressType) -> Result<c_int> {
+    unsafe {
+        // Traditionally there was a difference between reading data or
+        // instruction memory but not in modern systems.
+        ptrace_other(Request::PT_READ_D, pid, addr, 0)
+    }
+}
+
+/// Writes a word into the processes memory at the given address
+pub fn write(pid: Pid, addr: AddressType, data: c_int) -> Result<()> {
+    unsafe { ptrace_other(Request::PT_WRITE_D, pid, addr, data).map(|_| ()) }
+}

src/sys/ptrace.rs → src/sys/ptrace/linux.rs

@@ -173,8 +173,10 @@ libc_bitflags! {
 pub unsafe fn ptrace(request: Request, pid: Pid, addr: *mut c_void, data: *mut c_void) -> Result<c_long> {
     use self::Request::*;
     match request {
-        PTRACE_PEEKTEXT | PTRACE_PEEKDATA | PTRACE_PEEKUSER => ptrace_peek(request, pid, addr, data),
-        PTRACE_GETSIGINFO | PTRACE_GETEVENTMSG | PTRACE_SETSIGINFO | PTRACE_SETOPTIONS => Err(Error::UnsupportedOperation),
+        PTRACE_PEEKTEXT | PTRACE_PEEKDATA | PTRACE_PEEKUSER | PTRACE_GETSIGINFO | 
+            PTRACE_GETEVENTMSG | PTRACE_SETSIGINFO | PTRACE_SETOPTIONS | 
+            PTRACE_POKETEXT | PTRACE_POKEDATA | PTRACE_POKEUSER | 
+            PTRACE_KILL => Err(Error::UnsupportedOperation),
         _ => ptrace_other(request, pid, addr, data)
     }
 }
@@ -320,6 +322,15 @@ pub fn cont<T: Into<Option<Signal>>>(pid: Pid, sig: T) -> Result<()> {
     }
 }
 
+/// Issues a kill request as with `ptrace(PTRACE_KILL, ...)`
+///
+/// This request is equivalent to `ptrace(PTRACE_CONT, ..., SIGKILL);`
+pub fn kill(pid: Pid) -> Result<()> {
+    unsafe {
+        ptrace_other(Request::PTRACE_KILL, pid, ptr::null_mut(), ptr::null_mut()).map(|_| ())
+    }
+}
+
 /// Move the stopped tracee process forward by a single step as with 
 /// `ptrace(PTRACE_SINGLESTEP, ...)`
 ///
@@ -354,3 +365,16 @@ pub fn step<T: Into<Option<Signal>>>(pid: Pid, sig: T) -> Result<()> {
         ptrace_other(Request::PTRACE_SINGLESTEP, pid, ptr::null_mut(), data).map(|_| ())
     }
 }
+
+
+/// Reads a word from a processes memory at the given address
+pub fn read(pid: Pid, addr: *mut c_void) -> Result<c_long> {
+    ptrace_peek(Request::PTRACE_PEEKDATA, pid, addr, ptr::null_mut())
+}
+
+/// Writes a word into the processes memory at the given address
+pub fn write(pid: Pid, addr: *mut c_void, data: *mut c_void) -> Result<()> {
+    unsafe {
+        ptrace_other(Request::PTRACE_POKEDATA, pid, addr, data).map(|_| ())
+    }
+}

src/sys/ptrace/mod.rs

@@ -0,0 +1,22 @@
+///! Provides helpers for making ptrace system calls 
+
+#[cfg(any(target_os = "android", target_os = "linux"))]
+mod linux;
+
+#[cfg(any(target_os = "android", target_os = "linux"))]
+pub use self::linux::*;
+
+#[cfg(any(target_os = "dragonfly",
+          target_os = "freebsd",
+          target_os = "macos",
+          target_os = "netbsd",
+          target_os = "openbsd"))]
+mod bsd;
+
+#[cfg(any(target_os = "dragonfly",
+          target_os = "freebsd",
+          target_os = "macos",
+          target_os = "netbsd",
+          target_os = "openbsd"
+          ))]
+pub use self::bsd::*;

test/sys/mod.rs

@@ -27,5 +27,10 @@ mod test_uio;
 mod test_epoll;
 mod test_pthread;
 #[cfg(any(target_os = "android",
-          target_os = "linux"))]
+          target_os = "dragonfly",
+          target_os = "freebsd",
+          target_os = "linux",
+          target_os = "macos",
+          target_os = "netbsd",
+          target_os = "openbsd"))]
 mod test_ptrace;

test/sys/test_ptrace.rs

@@ -1,7 +1,9 @@
 use nix::Error;
 use nix::errno::Errno;
 use nix::unistd::getpid;
-use nix::sys::ptrace::{self, Options};
+use nix::sys::ptrace;
+#[cfg(any(target_os = "android", target_os = "linux"))]
+use nix::sys::ptrace::Options;
 
 #[cfg(any(target_os = "android", target_os = "linux"))]
 use std::mem;
@@ -11,25 +13,29 @@ fn test_ptrace() {
     // Just make sure ptrace can be called at all, for now.
     // FIXME: qemu-user doesn't implement ptrace on all arches, so permit ENOSYS
     let err = ptrace::attach(getpid()).unwrap_err();
-    assert!(err == Error::Sys(Errno::EPERM) || err == Error::Sys(Errno::ENOSYS));
+    assert!(err == Error::Sys(Errno::EPERM) || err == Error::Sys(Errno::EINVAL) ||
+            err == Error::Sys(Errno::ENOSYS));
 }
 
 // Just make sure ptrace_setoptions can be called at all, for now.
 #[test]
+#[cfg(any(target_os = "android", target_os = "linux"))]
 fn test_ptrace_setoptions() {
     let err = ptrace::setoptions(getpid(), Options::PTRACE_O_TRACESYSGOOD).unwrap_err();
     assert!(err != Error::UnsupportedOperation);
 }
 
 // Just make sure ptrace_getevent can be called at all, for now.
 #[test]
+#[cfg(any(target_os = "android", target_os = "linux"))]
 fn test_ptrace_getevent() {
     let err = ptrace::getevent(getpid()).unwrap_err();
     assert!(err != Error::UnsupportedOperation);
 }
 
 // Just make sure ptrace_getsiginfo can be called at all, for now.
 #[test]
+#[cfg(any(target_os = "android", target_os = "linux"))]
 fn test_ptrace_getsiginfo() {
     if let Err(Error::UnsupportedOperation) = ptrace::getsiginfo(getpid()) {
         panic!("ptrace_getsiginfo returns Error::UnsupportedOperation!");
@@ -38,6 +44,7 @@ fn test_ptrace_getsiginfo() {
 
 // Just make sure ptrace_setsiginfo can be called at all, for now.
 #[test]
+#[cfg(any(target_os = "android", target_os = "linux"))]
 fn test_ptrace_setsiginfo() {
     let siginfo = unsafe { mem::uninitialized() };
     if let Err(Error::UnsupportedOperation) = ptrace::setsiginfo(getpid(), &siginfo) {
@@ -50,10 +57,12 @@ fn test_ptrace_setsiginfo() {
 fn test_ptrace_cont() {
     use nix::sys::ptrace;
     use nix::sys::signal::{raise, Signal};
-    use nix::sys::wait::{waitpid, WaitStatus};
+    use nix::sys::wait::{waitpid, WaitPidFlag, WaitStatus};
     use nix::unistd::fork;
     use nix::unistd::ForkResult::*;
 
+    let _m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");
+
     // FIXME: qemu-user doesn't implement ptrace on all architectures
     // and retunrs ENOSYS in this case.
     // We (ab)use this behavior to detect the affected platforms
@@ -79,9 +88,18 @@ fn test_ptrace_cont() {
             assert_eq!(waitpid(child, None), Ok(WaitStatus::Stopped(child, Signal::SIGTRAP)));
             ptrace::cont(child, None).unwrap();
             assert_eq!(waitpid(child, None), Ok(WaitStatus::Stopped(child, Signal::SIGTRAP)));
-            ptrace::cont(child, Signal::SIGKILL).unwrap();
+            ptrace::cont(child, Some(Signal::SIGKILL)).unwrap();
             match waitpid(child, None) {
-                Ok(WaitStatus::Signaled(pid, Signal::SIGKILL, _)) if pid == child => {}
+                Ok(WaitStatus::Signaled(pid, Signal::SIGKILL, _)) if pid == child => {
+                    // FIXME It's been observed on some systems (apple) the 
+                    // tracee may not be killed but remain as a zombie process
+                    // affecting other wait based tests. Add an extra kill just
+                    // to make sure there are no zombies.
+                    let _ = waitpid(child, Some(WaitPidFlag::WNOHANG));
+                    while ptrace::cont(child, Some(Signal::SIGKILL)).is_ok() {
+                        let _ = waitpid(child, Some(WaitPidFlag::WNOHANG));
+                    }
+                }
                 _ => panic!("The process should have been killed"),
             }
         },