├── .gitignore ├── .travis.yml ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md ├── appveyor.yml ├── examples └── patch.rs └── src └── lib.rs /.gitignore: -------------------------------------------------------------------------------- 1 | target/ 2 | Cargo.lock 3 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: rust 2 | 3 | rust: 4 | - stable 5 | - beta 6 | - nightly 7 | 8 | matrix: 9 | allow_failures: 10 | - rust: nightly 11 | 12 | fast_finish: true 13 | 14 | script: 15 | - cargo test --verbose --all -- --test-threads=1 16 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "guerrilla" 3 | version = "0.1.5-alpha.0" 4 | description = "Guerrilla (or Monkey) Patching in Rust for (unsafe) fun and profit." 5 | license = "MIT/Apache-2.0" 6 | readme = "README.md" 7 | repository = "https://github.com/mehcode/guerrilla" 8 | documentation = "https://docs.rs/guerrilla" 9 | authors = ["Ryan Leckey "] 10 | 11 | [target.'cfg(any(unix, macos))'.dependencies] 12 | libc = "0.2.43" 13 | 14 | [target.'cfg(windows)'.dependencies] 15 | winapi = { version = "0.3.6", features = [ "memoryapi" ] } 16 | 17 | [dev-dependencies] 18 | chrono = "0.4.6" 19 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. For the purposes of this definition, 18 | "control" means (i) the power, direct or indirect, to cause the 19 | direction or management of such entity, whether by contract or 20 | otherwise, or (ii) ownership of fifty percent (50%) or more of the 21 | outstanding shares, or (iii) beneficial ownership of such entity. 22 | 23 | "You" (or "Your") shall mean an individual or Legal Entity 24 | exercising permissions granted by this License. 25 | 26 | "Source" form shall mean the preferred form for making modifications, 27 | including but not limited to software source code, documentation 28 | source, and configuration files. 29 | 30 | "Object" form shall mean any form resulting from mechanical 31 | transformation or translation of a Source form, including but 32 | not limited to compiled object code, generated documentation, 33 | and conversions to other media types. 34 | 35 | "Work" shall mean the work of authorship, whether in Source or 36 | Object form, made available under the License, as indicated by a 37 | copyright notice that is included in or attached to the work 38 | (an example is provided in the Appendix below). 39 | 40 | "Derivative Works" shall mean any work, whether in Source or Object 41 | form, that is based on (or derived from) the Work and for which the 42 | editorial revisions, annotations, elaborations, or other modifications 43 | represent, as a whole, an original work of authorship. For the purposes 44 | of this License, Derivative Works shall not include works that remain 45 | separable from, or merely link (or bind by name) to the interfaces of, 46 | the Work and Derivative Works thereof. 47 | 48 | "Contribution" shall mean any work of authorship, including 49 | the original version of the Work and any modifications or additions 50 | to that Work or Derivative Works thereof, that is intentionally 51 | submitted to Licensor for inclusion in the Work by the copyright owner 52 | or by an individual or Legal Entity authorized to submit on behalf of 53 | the copyright owner. For the purposes of this definition, "submitted" 54 | means any form of electronic, verbal, or written communication sent 55 | to the Licensor or its representatives, including but not limited to 56 | communication on electronic mailing lists, source code control systems, 57 | and issue tracking systems that are managed by, or on behalf of, the 58 | Licensor for the purpose of discussing and improving the Work, but 59 | excluding communication that is conspicuously marked or otherwise 60 | designated in writing by the copyright owner as "Not a Contribution." 61 | 62 | "Contributor" shall mean Licensor and any individual or Legal Entity 63 | on behalf of whom a Contribution has been received by Licensor and 64 | subsequently incorporated within the Work. 65 | 66 | 2. Grant of Copyright License. Subject to the terms and conditions of 67 | this License, each Contributor hereby grants to You a perpetual, 68 | worldwide, non-exclusive, no-charge, royalty-free, irrevocable 69 | copyright license to reproduce, prepare Derivative Works of, 70 | publicly display, publicly perform, sublicense, and distribute the 71 | Work and such Derivative Works in Source or Object form. 72 | 73 | 3. Grant of Patent License. Subject to the terms and conditions of 74 | this License, each Contributor hereby grants to You a perpetual, 75 | worldwide, non-exclusive, no-charge, royalty-free, irrevocable 76 | (except as stated in this section) patent license to make, have made, 77 | use, offer to sell, sell, import, and otherwise transfer the Work, 78 | where such license applies only to those patent claims licensable 79 | by such Contributor that are necessarily infringed by their 80 | Contribution(s) alone or by combination of their Contribution(s) 81 | with the Work to which such Contribution(s) was submitted. If You 82 | institute patent litigation against any entity (including a 83 | cross-claim or counterclaim in a lawsuit) alleging that the Work 84 | or a Contribution incorporated within the Work constitutes direct 85 | or contributory patent infringement, then any patent licenses 86 | granted to You under this License for that Work shall terminate 87 | as of the date such litigation is filed. 88 | 89 | 4. Redistribution. You may reproduce and distribute copies of the 90 | Work or Derivative Works thereof in any medium, with or without 91 | modifications, and in Source or Object form, provided that You 92 | meet the following conditions: 93 | 94 | (a) You must give any other recipients of the Work or 95 | Derivative Works a copy of this License; and 96 | 97 | (b) You must cause any modified files to carry prominent notices 98 | stating that You changed the files; and 99 | 100 | (c) You must retain, in the Source form of any Derivative Works 101 | that You distribute, all copyright, patent, trademark, and 102 | attribution notices from the Source form of the Work, 103 | excluding those notices that do not pertain to any part of 104 | the Derivative Works; and 105 | 106 | (d) If the Work includes a "NOTICE" text file as part of its 107 | distribution, then any Derivative Works that You distribute must 108 | include a readable copy of the attribution notices contained 109 | within such NOTICE file, excluding those notices that do not 110 | pertain to any part of the Derivative Works, in at least one 111 | of the following places: within a NOTICE text file distributed 112 | as part of the Derivative Works; within the Source form or 113 | documentation, if provided along with the Derivative Works; or, 114 | within a display generated by the Derivative Works, if and 115 | wherever such third-party notices normally appear. The contents 116 | of the NOTICE file are for informational purposes only and 117 | do not modify the License. You may add Your own attribution 118 | notices within Derivative Works that You distribute, alongside 119 | or as an addendum to the NOTICE text from the Work, provided 120 | that such additional attribution notices cannot be construed 121 | as modifying the License. 122 | 123 | You may add Your own copyright statement to Your modifications and 124 | may provide additional or different license terms and conditions 125 | for use, reproduction, or distribution of Your modifications, or 126 | for any such Derivative Works as a whole, provided Your use, 127 | reproduction, and distribution of the Work otherwise complies with 128 | the conditions stated in this License. 129 | 130 | 5. Submission of Contributions. Unless You explicitly state otherwise, 131 | any Contribution intentionally submitted for inclusion in the Work 132 | by You to the Licensor shall be under the terms and conditions of 133 | this License, without any additional terms or conditions. 134 | Notwithstanding the above, nothing herein shall supersede or modify 135 | the terms of any separate license agreement you may have executed 136 | with Licensor regarding such Contributions. 137 | 138 | 6. Trademarks. This License does not grant permission to use the trade 139 | names, trademarks, service marks, or product names of the Licensor, 140 | except as required for reasonable and customary use in describing the 141 | origin of the Work and reproducing the content of the NOTICE file. 142 | 143 | 7. Disclaimer of Warranty. Unless required by applicable law or 144 | agreed to in writing, Licensor provides the Work (and each 145 | Contributor provides its Contributions) on an "AS IS" BASIS, 146 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 147 | implied, including, without limitation, any warranties or conditions 148 | of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A 149 | PARTICULAR PURPOSE. You are solely responsible for determining the 150 | appropriateness of using or redistributing the Work and assume any 151 | risks associated with Your exercise of permissions under this License. 152 | 153 | 8. Limitation of Liability. In no event and under no legal theory, 154 | whether in tort (including negligence), contract, or otherwise, 155 | unless required by applicable law (such as deliberate and grossly 156 | negligent acts) or agreed to in writing, shall any Contributor be 157 | liable to You for damages, including any direct, indirect, special, 158 | incidental, or consequential damages of any character arising as a 159 | result of this License or out of the use or inability to use the 160 | Work (including but not limited to damages for loss of goodwill, 161 | work stoppage, computer failure or malfunction, or any and all 162 | other commercial damages or losses), even if such Contributor 163 | has been advised of the possibility of such damages. 164 | 165 | 9. Accepting Warranty or Additional Liability. While redistributing 166 | the Work or Derivative Works thereof, You may choose to offer, 167 | and charge a fee for, acceptance of support, warranty, indemnity, 168 | or other liability obligations and/or rights consistent with this 169 | License. However, in accepting such obligations, You may act only 170 | on Your own behalf and on Your sole responsibility, not on behalf 171 | of any other Contributor, and only if You agree to indemnify, 172 | defend, and hold each Contributor harmless for any liability 173 | incurred by, or claims asserted against, such Contributor by reason 174 | of your accepting any such warranty or additional liability. 175 | 176 | END OF TERMS AND CONDITIONS 177 | 178 | APPENDIX: How to apply the Apache License to your work. 179 | 180 | To apply the Apache License to your work, attach the following 181 | boilerplate notice, with the fields enclosed by brackets "[]" 182 | replaced with your own identifying information. (Don't include 183 | the brackets!) The text should be enclosed in the appropriate 184 | comment syntax for the file format. We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright 2018 Ryan Leckey 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /LICENSE-MIT: -------------------------------------------------------------------------------- 1 | Copyright (c) 2018 Ryan Leckey 2 | 3 | Permission is hereby granted, free of charge, to any 4 | person obtaining a copy of this software and associated 5 | documentation files (the "Software"), to deal in the 6 | Software without restriction, including without 7 | limitation the rights to use, copy, modify, merge, 8 | publish, distribute, sublicense, and/or sell copies of 9 | the Software, and to permit persons to whom the Software 10 | is furnished to do so, subject to the following 11 | conditions: 12 | 13 | The above copyright notice and this permission notice 14 | shall be included in all copies or substantial portions 15 | of the Software. 16 | 17 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 18 | ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 19 | TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 20 | PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 21 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 22 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 24 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 25 | DEALINGS IN THE SOFTWARE. 26 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Guerrilla 2 | [![Crates.io](https://img.shields.io/crates/v/guerrilla.svg?style=popout-square)](https://crates.io/crates/guerrilla) 3 | [![Travis (.com)](https://img.shields.io/travis/com/mehcode/guerrilla.svg?label=Travis%20CI&style=flat-square)](https://travis-ci.com/mehcode/guerrilla) 4 | [![AppVeyor](https://img.shields.io/appveyor/ci/mehcode/guerrilla.svg?label=AppVeyor&style=flat-square)](https://ci.appveyor.com/project/mehcode/guerrilla) 5 | ![License](https://img.shields.io/crates/l/guerrilla.svg?style=popout-square) 6 | > Guerrilla (or Monkey) Patching in Rust for (unsafe) fun and profit. 7 | 8 | Provides aribtrary monkey patching in Rust. Please do not use this crate for anything outside of testing. 9 | It will not end well. 10 | 11 | Can patch (almost) any function in Rust (free, associated, instance, generic, etc.). 12 | 13 | ## Usage 14 | 15 | ```rust 16 | extern crate guerrilla; 17 | 18 | #[inline(never)] 19 | fn say_hi(name: &str) { 20 | println!("hello, {}", name); 21 | } 22 | 23 | fn main() { 24 | // Variadic generics would be wondeful so we could have a [guerrilla::patch] 25 | let _guard = guerrilla::patch1(say_hi, |name| { 26 | // So sneaky... like a sneaky sneaky snek 27 | println!("bye, {}", name); 28 | }); 29 | 30 | // [...] 31 | // Thousands of lines codes further in the project 32 | // [...] 33 | 34 | say_hi("Steve"); 35 | 36 | // Once the guard is dropped the patch reverts the function to its original 37 | // behavior. 38 | drop(_guard); 39 | 40 | say_hi("Bob"); 41 | } 42 | ``` 43 | 44 | ## License 45 | 46 | Licensed under either of 47 | 48 | * Apache License, Version 2.0 49 | ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) 50 | * MIT license 51 | ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) 52 | 53 | at your option. 54 | 55 | ## Contribution 56 | 57 | Unless you explicitly state otherwise, any contribution intentionally submitted 58 | for inclusion in the work by you, as defined in the Apache-2.0 license, shall be 59 | dual licensed as above, without any additional terms or conditions. 60 | 61 | ## Credits 62 | 63 | Inspired (and derived) from [monkey-patching-in-go](https://bou.ke/blog/monkey-patching-in-go/). 64 | -------------------------------------------------------------------------------- /appveyor.yml: -------------------------------------------------------------------------------- 1 | os: Visual Studio 2017 2 | 3 | environment: 4 | matrix: 5 | # Stable 64-bit MSVC 6 | - channel: stable 7 | target: x86_64-pc-windows-msvc 8 | 9 | # Stable 32-bit MSVC 10 | - channel: stable 11 | target: i686-pc-windows-msvc 12 | 13 | # Beta 64-bit MSVC 14 | - channel: beta 15 | target: x86_64-pc-windows-msvc 16 | 17 | # Beta 32-bit MSVC 18 | - channel: beta 19 | target: i686-pc-windows-msvc 20 | 21 | # Nightly 64-bit MSVC 22 | - channel: nightly 23 | target: x86_64-pc-windows-msvc 24 | 25 | # Nightly 32-bit MSVC 26 | - channel: nightly 27 | target: i686-pc-windows-msvc 28 | 29 | # Stable 64-bit GNU 30 | - channel: stable 31 | target: x86_64-pc-windows-gnu 32 | 33 | # Stable 32-bit GNU 34 | - channel: stable 35 | target: i686-pc-windows-gnu 36 | 37 | # Beta 64-bit GNU 38 | - channel: beta 39 | target: x86_64-pc-windows-gnu 40 | 41 | # Beta 32-bit GNU 42 | - channel: beta 43 | target: i686-pc-windows-gnu 44 | 45 | # Nightly 64-bit GNU 46 | - channel: nightly 47 | target: x86_64-pc-windows-gnu 48 | 49 | # Nightly 32-bit GNU 50 | - channel: nightly 51 | target: i686-pc-windows-gnu 52 | 53 | matrix: 54 | allow_failures: 55 | - channel: nightly 56 | 57 | install: 58 | - appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe 59 | - rustup-init -yv --default-toolchain %channel% --default-host %target% 60 | - set PATH=%PATH%;%USERPROFILE%\.cargo\bin 61 | - rustc -vV 62 | - cargo -vV 63 | 64 | build: false 65 | 66 | test_script: 67 | - cargo test --verbose -- --test-threads=1 68 | -------------------------------------------------------------------------------- /examples/patch.rs: -------------------------------------------------------------------------------- 1 | extern crate guerrilla; 2 | 3 | #[inline(never)] 4 | fn say_hi(name: &str) { 5 | println!("hello, {}", name); 6 | } 7 | 8 | fn main() { 9 | // Variadic generics would be wondeful so we could have a [guerrilla::patch] 10 | let _guard = guerrilla::patch1(say_hi, |name| { 11 | // So sneaky... like a sneaky sneaky snek 12 | println!("bye, {}", name); 13 | }); 14 | 15 | // [...] 16 | // Thousands of lines codes further in the project 17 | // [...] 18 | 19 | say_hi("Steve"); 20 | 21 | // Once the guard is dropped the patch reverts the function to its original 22 | // behavior. 23 | drop(_guard); 24 | 25 | say_hi("Bob"); 26 | } 27 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | #![no_std] 2 | 3 | #[cfg(test)] 4 | extern crate chrono; 5 | 6 | #[cfg(any(macos, unix))] 7 | extern crate libc; 8 | 9 | #[cfg(test)] 10 | #[macro_use] 11 | extern crate std; 12 | 13 | #[cfg(windows)] 14 | extern crate winapi; 15 | 16 | #[cfg(windows)] 17 | unsafe fn copy_to_protected_address(dst: *mut u8, src: &[u8]) { 18 | use winapi::shared::minwindef::DWORD; 19 | use winapi::um::memoryapi::VirtualProtect; 20 | use winapi::um::winnt::PAGE_EXECUTE_READWRITE; 21 | 22 | let mut old_permissions: DWORD = 0; 23 | let rv = VirtualProtect( 24 | dst as _, 25 | src.len(), 26 | PAGE_EXECUTE_READWRITE, 27 | (&mut old_permissions) as _, 28 | ); 29 | 30 | assert_eq!(rv, 1); 31 | 32 | core::ptr::copy(src.as_ptr(), dst, src.len()); 33 | 34 | let mut temp: DWORD = 0; 35 | let rv = VirtualProtect(dst as _, src.len(), old_permissions, (&mut temp) as _); 36 | 37 | assert_eq!(rv, 1); 38 | } 39 | 40 | #[cfg(any(macos, unix))] 41 | unsafe fn copy_to_protected_address(dst: *mut u8, src: &[u8]) { 42 | use libc::{c_void, mprotect, sysconf, PROT_EXEC, PROT_READ, PROT_WRITE, _SC_PAGESIZE}; 43 | 44 | let page_size = sysconf(_SC_PAGESIZE) as usize; 45 | let page_start = ((dst as usize) & !(page_size - 1)) as *mut c_void; 46 | 47 | let rv = mprotect(page_start, page_size, PROT_EXEC | PROT_READ | PROT_WRITE); 48 | assert_eq!(rv, 0); 49 | 50 | core::ptr::copy(src.as_ptr(), dst, src.len()); 51 | 52 | let rv = mprotect(page_start, page_size, PROT_EXEC | PROT_READ); 53 | assert_eq!(rv, 0); 54 | } 55 | 56 | #[cfg(target_arch = "x86")] 57 | const JMP_MAX_SIZE: usize = 7; 58 | 59 | #[cfg(target_arch = "x86_64")] 60 | const JMP_MAX_SIZE: usize = 12; 61 | 62 | #[cfg(target_arch = "x86")] 63 | #[inline] 64 | fn assemble_jmp_to_address(address: usize, mut relative: isize) -> ([u8; JMP_MAX_SIZE], usize) { 65 | use core::{i32, i8}; 66 | if (relative - 2 >= (i8::MIN as isize)) && (relative - 2 <= (i8::MAX as isize)) { 67 | relative -= 2; 68 | ( 69 | [ 70 | // jmp rel8 71 | 0xEB, 72 | relative as u8, 73 | 0, 74 | 0, 75 | 0, 76 | 0, 77 | 0, 78 | ], 79 | 2, 80 | ) 81 | } else if (relative - 5 >= (i32::MIN as isize)) && (relative - 5 <= (i32::MAX as isize)) { 82 | relative -= 5; 83 | ( 84 | [ 85 | // jmp rel32 86 | 0xE9, 87 | relative as u8, 88 | (relative >> 8) as u8, 89 | (relative >> 16) as u8, 90 | (relative >> 24) as u8, 91 | 0, 92 | 0, 93 | ], 94 | 5, 95 | ) 96 | } else { 97 | ( 98 | [ 99 | // mov edx, # 100 | 0xBA, 101 | address as u8, 102 | (address >> 8) as u8, 103 | (address >> 16) as u8, 104 | (address >> 24) as u8, 105 | // jmp edx 106 | 0xFF, 107 | 0xE2, 108 | ], 109 | 7, 110 | ) 111 | } 112 | } 113 | 114 | #[cfg(target_arch = "x86_64")] 115 | #[inline] 116 | fn assemble_jmp_to_address(address: usize, mut relative: isize) -> ([u8; JMP_MAX_SIZE], usize) { 117 | use core::{i32, i8}; 118 | if (relative - 2 >= (i8::MIN as isize)) && (relative - 2 <= (i8::MAX as isize)) { 119 | relative -= 2; 120 | ( 121 | [ 122 | // jmp rel8 123 | 0xEB, 124 | relative as u8, 125 | 0, 126 | 0, 127 | 0, 128 | 0, 129 | 0, 130 | 0, 131 | 0, 132 | 0, 133 | 0, 134 | 0, 135 | ], 136 | 2, 137 | ) 138 | } else if (relative - 5 >= (i32::MIN as isize)) && (relative - 5 <= (i32::MAX as isize)) { 139 | relative -= 5; 140 | ( 141 | [ 142 | // jmp rel32 143 | 0xE9, 144 | relative as u8, 145 | (relative >> 8) as u8, 146 | (relative >> 16) as u8, 147 | (relative >> 24) as u8, 148 | 0, 149 | 0, 150 | 0, 151 | 0, 152 | 0, 153 | 0, 154 | 0, 155 | ], 156 | 5, 157 | ) 158 | } else { 159 | ( 160 | [ 161 | // movabs rdx, # 162 | 0x48, 163 | 0xBA, 164 | address as u8, 165 | (address >> 8) as u8, 166 | (address >> 16) as u8, 167 | (address >> 24) as u8, 168 | (address >> 32) as u8, 169 | (address >> 40) as u8, 170 | (address >> 48) as u8, 171 | (address >> 56) as u8, 172 | // jmp rdx 173 | 0xFF, 174 | 0xE2, 175 | ], 176 | 12, 177 | ) 178 | } 179 | } 180 | 181 | /// When this structure is dropped (falls out of scope), the patch will be reverted and the function will return 182 | /// to its original state. 183 | pub struct PatchGuard { 184 | ptr: *mut u8, 185 | len: usize, 186 | data: [u8; JMP_MAX_SIZE], 187 | } 188 | 189 | impl Drop for PatchGuard { 190 | fn drop(&mut self) { 191 | unsafe { 192 | copy_to_protected_address(self.ptr, &self.data[..self.len]); 193 | } 194 | } 195 | } 196 | 197 | #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] 198 | const UNSAFE_LEADING_BYTES: [u8; 4] = [ 199 | 0xC3, // ret near 200 | 0xCB, // ret far 201 | 0xC2, // ret near imm16 202 | 0xCA, // ret far imm16 203 | ]; 204 | 205 | macro_rules! define_patch { 206 | ($name:ident($($arguments:ident,)*)) => ( 207 | /// Patch replaces a function with another. Accepts closures as replacement functions as long as they 208 | /// do not bind to the environment. 209 | pub fn $name(target: fn($($arguments,)*) -> R, func: fn($($arguments,)*) -> R) -> PatchGuard { 210 | let target = target as *mut u8; 211 | let mut original = [0; JMP_MAX_SIZE]; 212 | 213 | let leading_byte = unsafe { (*target) }; 214 | if UNSAFE_LEADING_BYTES.contains(&leading_byte) { 215 | panic!("target function is too small (1 byte) to patch"); 216 | } 217 | 218 | let target_address = target as usize; 219 | let func_address = func as usize; 220 | 221 | let relative = if target_address > func_address { 222 | -((target_address - func_address) as isize) 223 | } else { 224 | ((func_address - target_address) as isize) 225 | }; 226 | 227 | let (patch, len) = assemble_jmp_to_address(func_address, relative); 228 | 229 | unsafe { 230 | core::ptr::copy(target, original.as_mut_ptr(), JMP_MAX_SIZE); 231 | } 232 | 233 | unsafe { 234 | copy_to_protected_address(target, &patch[..len]); 235 | } 236 | 237 | PatchGuard { 238 | ptr: target, 239 | len, 240 | data: original, 241 | } 242 | } 243 | ); 244 | } 245 | 246 | define_patch!(patch0()); 247 | define_patch!(patch1(A,)); 248 | define_patch!(patch2(A, B,)); 249 | define_patch!(patch3(A, B, C,)); 250 | define_patch!(patch4(A, B, C, D,)); 251 | define_patch!(patch5(A, B, C, D, E,)); 252 | define_patch!(patch6(A, B, C, D, E, F,)); 253 | define_patch!(patch7(A, B, C, D, E, F, G,)); 254 | define_patch!(patch8(A, B, C, D, E, F, G, H,)); 255 | define_patch!(patch9(A, B, C, D, E, F, G, H, I,)); 256 | 257 | #[cfg(test)] 258 | #[inline(never)] 259 | fn tiny() {} 260 | 261 | #[cfg(test)] 262 | #[inline(never)] 263 | fn the_ultimate_question() -> u32 { 264 | 42 265 | } 266 | 267 | #[cfg(test)] 268 | #[inline(never)] 269 | fn other_question() -> u32 { 270 | 23 271 | } 272 | 273 | #[cfg(test)] 274 | #[inline(never)] 275 | fn default() -> T { 276 | T::default() 277 | } 278 | 279 | #[cfg(test)] 280 | mod tests { 281 | use super::*; 282 | use chrono::{Datelike, TimeZone, Timelike, Utc}; 283 | 284 | #[test] 285 | fn test_patch() { 286 | assert_eq!(the_ultimate_question(), 42); 287 | 288 | { 289 | let _guard = patch0(the_ultimate_question, || 24); 290 | 291 | assert_eq!(the_ultimate_question(), 24); 292 | } 293 | 294 | assert_eq!(the_ultimate_question(), 42); 295 | } 296 | 297 | // Test smallest possible function (in debug mode) 298 | // In 32-bit this should panic and properly detect we cannot patch a 1-byte function 299 | #[test] 300 | fn test_tiny() { 301 | assert_eq!(tiny(), ()); 302 | 303 | if let Err(err) = std::panic::catch_unwind(|| { 304 | let _guard = patch0(tiny, || ()); 305 | 306 | assert_eq!(tiny(), ()); 307 | assert_eq!(the_ultimate_question(), 42); 308 | assert_eq!(other_question(), 23); 309 | }) { 310 | let err = err.downcast::<&'static str>().unwrap(); 311 | assert_eq!(*err, "target function is too small (1 byte) to patch"); 312 | } 313 | 314 | assert_eq!(tiny(), ()); 315 | } 316 | 317 | #[test] 318 | fn test_functions_independent() { 319 | assert_eq!(the_ultimate_question(), 42); 320 | assert_eq!(other_question(), 23); 321 | 322 | { 323 | let _guard = patch0(the_ultimate_question, || 32); 324 | 325 | assert_eq!(the_ultimate_question(), 32); 326 | assert_eq!(other_question(), 23); 327 | } 328 | 329 | assert_eq!(the_ultimate_question(), 42); 330 | assert_eq!(other_question(), 23); 331 | } 332 | 333 | #[test] 334 | fn test_patch_generic() { 335 | assert_eq!(default::(), 0); 336 | 337 | { 338 | let _guard = patch0(default::, || 1); 339 | 340 | assert_eq!(default::(), 1); 341 | } 342 | 343 | assert_eq!(default::(), 0); 344 | } 345 | 346 | #[test] 347 | fn test_patch_external() { 348 | let now = Utc::now(); 349 | assert!(now.year() >= 2018); 350 | 351 | { 352 | let _guard = patch0(Utc::now, || Utc.ymd(1, 1, 1).and_hms(1, 1, 1)); 353 | 354 | let now = Utc::now(); 355 | assert_eq!(now.year(), 1); 356 | assert_eq!(now.hour(), 1); 357 | } 358 | 359 | assert!(now.year() >= 2018); 360 | } 361 | 362 | #[test] 363 | fn test_patch_existing_local() { 364 | assert_eq!(the_ultimate_question(), 42); 365 | assert_eq!(other_question(), 23); 366 | 367 | { 368 | let _guard = patch0(the_ultimate_question, other_question); 369 | 370 | assert_eq!(the_ultimate_question(), 23); 371 | assert_eq!(other_question(), 23); 372 | } 373 | 374 | assert_eq!(the_ultimate_question(), 42); 375 | assert_eq!(other_question(), 23); 376 | } 377 | } 378 | --------------------------------------------------------------------------------