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// Copyright 2015 Big Switch Networks, Inc // (Algorithms for uBPF syscalls, originally in C) // Copyright 2016 6WIND S.A. <quentin.monnet@6wind.com> // (Translation to Rust, other syscalls) // // Licensed under the Apache License, Version 2.0 <http://www.apache.org/licenses/LICENSE-2.0> or // the MIT license <http://opensource.org/licenses/MIT>, at your option. This file may not be // copied, modified, or distributed except according to those terms. //! This module implements some built-in syscalls that can be called from within an eBPF program. //! //! These syscalls may originate from several places: //! //! * Some of them mimic the syscalls available in the Linux kernel. //! * Some of them were proposed as example syscalls in uBPF and they were adapted here. //! * Other syscalls may be specific to rbpf. //! //! The prototype for syscalls is always the same: five `u64` as arguments, and a `u64` as a return //! value. Hence some syscalls have unused arguments, or return a 0 value in all cases, in order to //! respect this convention. #![cfg_attr(rustfmt, rustfmt_skip)] extern crate libc; use std::u64; use time; use crate::{ebpf::{EbpfError, UserDefinedError}, memory_region::{MemoryRegion, translate_addr}}; // syscalls associated to kernel syscalls // See also linux/include/uapi/linux/bpf.h in Linux kernel sources. // bpf_ktime_getns() /// Index of syscall `bpf_ktime_getns()`, equivalent to `bpf_time_getns()`, in Linux kernel, see /// <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/bpf.h>. pub const BPF_KTIME_GETNS_IDX: u32 = 5; /// Get monotonic time (since boot time) in nanoseconds. All arguments are unused. /// /// # Examples /// /// ``` /// use solana_rbpf::syscalls::bpf_time_getns; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// let regions = [MemoryRegion::default()]; /// let t = bpf_time_getns::<UserError>(0, 0, 0, 0, 0, ®ions, ®ions).unwrap(); /// let d = t / 10u64.pow(9) / 60 / 60 / 24; /// let h = (t / 10u64.pow(9) / 60 / 60) % 24; /// let m = (t / 10u64.pow(9) / 60 ) % 60; /// let s = (t / 10u64.pow(9)) % 60; /// let ns = t % 10u64.pow(9); /// println!("Uptime: {:#x} == {} days {}:{}:{}, {} ns", t, d, h, m, s, ns); /// ``` #[allow(dead_code)] pub fn bpf_time_getns<E: UserDefinedError> ( _arg1: u64, _arg2: u64, _arg3: u64, _arg4: u64, _arg5: u64, _ro_regions: &[MemoryRegion], _rw_regions: &[MemoryRegion], ) -> Result<u64, EbpfError<E>> { Ok(time::precise_time_ns()) } // bpf_trace_printk() /// Index of syscall `bpf_trace_printk()`, equivalent to `bpf_trace_printf()`, in Linux kernel, see /// <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/bpf.h>. pub const BPF_TRACE_PRINTK_IDX: u32 = 6; /// Prints its **last three** arguments to standard output. The **first two** arguments are /// **unused**. Returns the number of bytes written. /// /// By ignoring the first two arguments, it creates a syscall that will have a behavior similar to /// the one of the equivalent syscall `bpf_trace_printk()` from Linux kernel. /// /// # Examples /// /// ``` /// use solana_rbpf::syscalls::bpf_trace_printf; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// let regions = [MemoryRegion::default()]; /// let res = bpf_trace_printf::<UserError>(0, 0, 1, 15, 32, ®ions, ®ions).unwrap(); /// assert_eq!(res as usize, "bpf_trace_printf: 0x1, 0xf, 0x20\n".len()); /// ``` /// /// This will print `bpf_trace_printf: 0x1, 0xf, 0x20`. /// /// The eBPF code needed to perform the call in this example would be nearly identical to the code /// obtained by compiling the following code from C to eBPF with clang: /// /// ```c /// #include <linux/bpf.h> /// #include "path/to/linux/samples/bpf/bpf_syscalls.h" /// /// int main(struct __sk_buff *skb) /// { /// // Only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed. /// // See <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/kernel/trace/bpf_trace.c>. /// char *fmt = "bpf_trace_printk %llx, %llx, %llx\n"; /// return bpf_trace_printk(fmt, sizeof(fmt), 1, 15, 32); /// } /// ``` /// /// This would equally print the three numbers in `/sys/kernel/debug/tracing` file each time the /// program is run. #[allow(dead_code)] pub fn bpf_trace_printf<E: UserDefinedError> ( _arg1: u64, _arg2: u64, arg3: u64, arg4: u64, arg5: u64, _ro_regions: &[MemoryRegion], _rw_regions: &[MemoryRegion] ) -> Result<u64, EbpfError<E>> { println!("bpf_trace_printf: {:#x}, {:#x}, {:#x}", arg3, arg4, arg5); let size_arg = | x | { if x == 0 { 1 } else { (x as f64).log(16.0).floor() as u64 + 1 } }; Ok("bpf_trace_printf: 0x, 0x, 0x\n".len() as u64 + size_arg(arg3) + size_arg(arg4) + size_arg(arg5)) } // syscalls coming from uBPF <https://github.com/iovisor/ubpf/blob/master/vm/test.c> /// The idea is to assemble five bytes into a single `u64`. For compatibility with the syscalls API, /// each argument must be a `u64`. /// /// # Examples /// /// ``` /// use solana_rbpf::syscalls::gather_bytes; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// let regions = [MemoryRegion::default()]; /// let gathered = gather_bytes::<UserError>(0x11, 0x22, 0x33, 0x44, 0x55, ®ions, ®ions).unwrap(); /// assert_eq!(gathered, 0x1122334455); /// ``` pub fn gather_bytes<E: UserDefinedError> ( arg1: u64, arg2: u64, arg3: u64, arg4: u64, arg5: u64, _ro_regions: &[MemoryRegion], _rw_regions: &[MemoryRegion] ) -> Result<u64, EbpfError<E>> { Ok(arg1.wrapping_shl(32) | arg2.wrapping_shl(24) | arg3.wrapping_shl(16) | arg4.wrapping_shl(8) | arg5) } /// Same as `void *memfrob(void *s, size_t n);` in `string.h` in C. See the GNU manual page (in /// section 3) for `memfrob`. The memory is directly modified, and the syscall returns 0 in all /// cases. Arguments 3 to 5 are unused. /// /// # Examples /// /// ``` /// use solana_rbpf::syscalls::memfrob; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// let val = vec![0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x22, 0x33]; /// let val_va = 0x1000; /// let regions = [MemoryRegion::new_from_slice(&val, val_va)]; /// /// memfrob::<UserError>(val_va, 8, 0, 0, 0, ®ions, ®ions); /// assert_eq!(val, vec![0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x3b, 0x08, 0x19]); /// memfrob::<UserError>(val_va, 8, 0, 0, 0, ®ions, ®ions); /// assert_eq!(val, vec![0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x22, 0x33]); /// ``` pub fn memfrob<E: UserDefinedError> ( addr: u64, len: u64, _arg3: u64, _arg4: u64, _arg5: u64, _ro_regions: &[MemoryRegion], rw_regions: &[MemoryRegion] ) -> Result<u64, EbpfError<E>> { let host_addr = translate_addr(addr, len as usize, "Store", 0, rw_regions)?; for i in 0..len { unsafe { let mut p = (host_addr + i) as *mut u8; *p ^= 0b101010; } } Ok(0) } // TODO: Try again when asm!() is available in stable Rust. // #![feature(asm)] // #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] // #[allow(unused_variables)] // pub fn memfrob (ptr: u64, len: u64, arg3: u64, arg4: u64, arg5: u64) -> Result<u64, Error> { // unsafe { // asm!( // "mov $0xf0, %rax" // ::: "mov $0xf1, %rcx" // ::: "mov $0xf2, %rdx" // ::: "mov $0xf3, %rsi" // ::: "mov $0xf4, %rdi" // ::: "mov $0xf5, %r8" // ::: "mov $0xf6, %r9" // ::: "mov $0xf7, %r10" // ::: "mov $0xf8, %r11" // ); // } // 0 // } /// Compute and return the square root of argument 1, cast as a float. Arguments 2 to 5 are /// unused. /// /// # Examples /// /// ``` /// use solana_rbpf::syscalls::sqrti; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// let regions = [MemoryRegion::default()]; /// let x = sqrti::<UserError>(9, 0, 0, 0, 0, ®ions, ®ions).unwrap(); /// assert_eq!(x, 3); /// ``` #[allow(dead_code)] pub fn sqrti<E: UserDefinedError> ( arg1: u64, _arg2: u64, _arg3: u64, _arg4: u64, _arg5: u64, _ro_regions: &[MemoryRegion], _rw_regions: &[MemoryRegion] ) -> Result<u64, EbpfError<E>> { Ok((arg1 as f64).sqrt() as u64) } /// C-like `strcmp`, return 0 if the strings are equal, and a non-null value otherwise. /// /// # Examples /// /// ``` /// use solana_rbpf::syscalls::strcmp; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// let foo = "This is a string."; /// let bar = "This is another sting."; /// let va_foo = 0x1000; /// let va_bar = 0x2000; /// let regions = [MemoryRegion::new_from_slice(foo.as_bytes(), va_foo)]; /// assert!(strcmp::<UserError>(va_foo, va_foo, 0, 0, 0, ®ions, ®ions).unwrap() == 0); /// let regions = [MemoryRegion::new_from_slice(foo.as_bytes(), va_foo), /// MemoryRegion::new_from_slice(bar.as_bytes(), va_bar)]; /// assert!(strcmp::<UserError>(va_foo, va_bar, 0, 0, 0, ®ions, ®ions).unwrap() != 0); /// ``` #[allow(dead_code)] pub fn strcmp<E: UserDefinedError> ( arg1: u64, arg2: u64, _arg3: u64, _arg4: u64, _arg5: u64, ro_regions: &[MemoryRegion], _rw_regions: &[MemoryRegion] ) -> Result<u64, EbpfError<E>> { // C-like strcmp, maybe shorter than converting the bytes to string and comparing? if arg1 == 0 || arg2 == 0 { return Ok(u64::MAX); } let mut a = translate_addr(arg1, 1, "Load", 0, ro_regions)?; let mut b = translate_addr(arg2, 1, "Load", 0, ro_regions)?; unsafe { let mut a_val = *(a as *const u8); let mut b_val = *(b as *const u8); while a_val == b_val && a_val != 0 && b_val != 0 { a +=1 ; b +=1 ; a_val = *(a as *const u8); b_val = *(b as *const u8); } if a_val >= b_val { Ok((a_val - b_val) as u64) } else { Ok((b_val - a_val) as u64) } } } // Some additional syscalls /// Returns a random u64 value comprised between `min` and `max` values (inclusive). Arguments 3 to /// 5 are unused. /// /// Relies on `rand()` function from libc, so `libc::srand()` should be called once before this /// syscall is used. /// /// # Examples /// /// ``` /// extern crate libc; /// extern crate solana_rbpf; /// extern crate time; /// /// use solana_rbpf::syscalls::rand; /// use solana_rbpf::memory_region::MemoryRegion; /// use solana_rbpf::user_error::UserError; /// /// unsafe { /// libc::srand(time::precise_time_ns() as u32) /// } /// /// let regions = [MemoryRegion::default()]; /// let n = rand::<UserError>(3, 6, 0, 0, 0, ®ions, ®ions).unwrap(); /// assert!(3 <= n && n <= 6); /// ``` #[allow(dead_code)] pub fn rand<E: UserDefinedError> ( min: u64, max: u64, _arg3: u64, _arg4: u64, _arg5: u64, _ro_regions: &[MemoryRegion], _rw_regions: &[MemoryRegion], ) -> Result<u64, EbpfError<E>> { let mut n = unsafe { (libc::rand() as u64).wrapping_shl(32) + libc::rand() as u64 }; if min < max { n = n % (max + 1 - min) + min; }; Ok(n) }