commit c9385a3f2161dbda6072384bbbe6947beec97613 Author: Gary Guo Date: Wed Aug 25 02:55:49 2021 +0100 FDE finder diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..98ae53c --- /dev/null +++ b/.gitignore @@ -0,0 +1,3 @@ +.vscode/ +target +Cargo.lock diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..e592fc7 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,15 @@ +[package] +name = "unwind" +version = "0.1.0" +authors = ["Gary Guo "] +edition = "2018" + +[dependencies] +gimli = { version = "0.25.0", default-features = false, features = ["read"] } +libc = "0.2" +fallible-iterator = "0.1" +log = "0.4" +once_cell = "1.8" + +[profile.release] +debug = true diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..1b5ec8b --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,176 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + +TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + +1. Definitions. + + "License" shall mean the terms and conditions for use, reproduction, + and distribution as defined by Sections 1 through 9 of this document. + + "Licensor" shall mean the copyright owner or entity authorized by + the copyright owner that is granting the License. + + "Legal Entity" shall mean the union of the acting entity and all + other entities that control, are controlled by, or are under common + control with that entity. For the purposes of this definition, + "control" means (i) the power, direct or indirect, to cause the + direction or management of such entity, whether by contract or + otherwise, or (ii) ownership of fifty percent (50%) or more of the + outstanding shares, or (iii) beneficial ownership of such entity. + + "You" (or "Your") shall mean an individual or Legal Entity + exercising permissions granted by this License. + + "Source" form shall mean the preferred form for making modifications, + including but not limited to software source code, documentation + source, and configuration files. + + "Object" form shall mean any form resulting from mechanical + transformation or translation of a Source form, including but + not limited to compiled object code, generated documentation, + and conversions to other media types. + + "Work" shall mean the work of authorship, whether in Source or + Object form, made available under the License, as indicated by a + copyright notice that is included in or attached to the work + (an example is provided in the Appendix below). + + "Derivative Works" shall mean any work, whether in Source or Object + form, that is based on (or derived from) the Work and for which the + editorial revisions, annotations, elaborations, or other modifications + represent, as a whole, an original work of authorship. For the purposes + of this License, Derivative Works shall not include works that remain + separable from, or merely link (or bind by name) to the interfaces of, + the Work and Derivative Works thereof. + + "Contribution" shall mean any work of authorship, including + the original version of the Work and any modifications or additions + to that Work or Derivative Works thereof, that is intentionally + submitted to Licensor for inclusion in the Work by the copyright owner + or by an individual or Legal Entity authorized to submit on behalf of + the copyright owner. For the purposes of this definition, "submitted" + means any form of electronic, verbal, or written communication sent + to the Licensor or its representatives, including but not limited to + communication on electronic mailing lists, source code control systems, + and issue tracking systems that are managed by, or on behalf of, the + Licensor for the purpose of discussing and improving the Work, but + excluding communication that is conspicuously marked or otherwise + designated in writing by the copyright owner as "Not a Contribution." + + "Contributor" shall mean Licensor and any individual or Legal Entity + on behalf of whom a Contribution has been received by Licensor and + subsequently incorporated within the Work. + +2. Grant of Copyright License. Subject to the terms and conditions of + this License, each Contributor hereby grants to You a perpetual, + worldwide, non-exclusive, no-charge, royalty-free, irrevocable + copyright license to reproduce, prepare Derivative Works of, + publicly display, publicly perform, sublicense, and distribute the + Work and such Derivative Works in Source or Object form. + +3. Grant of Patent License. Subject to the terms and conditions of + this License, each Contributor hereby grants to You a perpetual, + worldwide, non-exclusive, no-charge, royalty-free, irrevocable + (except as stated in this section) patent license to make, have made, + use, offer to sell, sell, import, and otherwise transfer the Work, + where such license applies only to those patent claims licensable + by such Contributor that are necessarily infringed by their + Contribution(s) alone or by combination of their Contribution(s) + with the Work to which such Contribution(s) was submitted. If You + institute patent litigation against any entity (including a + cross-claim or counterclaim in a lawsuit) alleging that the Work + or a Contribution incorporated within the Work constitutes direct + or contributory patent infringement, then any patent licenses + granted to You under this License for that Work shall terminate + as of the date such litigation is filed. + +4. Redistribution. You may reproduce and distribute copies of the + Work or Derivative Works thereof in any medium, with or without + modifications, and in Source or Object form, provided that You + meet the following conditions: + + (a) You must give any other recipients of the Work or + Derivative Works a copy of this License; and + + (b) You must cause any modified files to carry prominent notices + stating that You changed the files; and + + (c) You must retain, in the Source form of any Derivative Works + that You distribute, all copyright, patent, trademark, and + attribution notices from the Source form of the Work, + excluding those notices that do not pertain to any part of + the Derivative Works; and + + (d) If the Work includes a "NOTICE" text file as part of its + distribution, then any Derivative Works that You distribute must + include a readable copy of the attribution notices contained + within such NOTICE file, excluding those notices that do not + pertain to any part of the Derivative Works, in at least one + of the following places: within a NOTICE text file distributed + as part of the Derivative Works; within the Source form or + documentation, if provided along with the Derivative Works; or, + within a display generated by the Derivative Works, if and + wherever such third-party notices normally appear. The contents + of the NOTICE file are for informational purposes only and + do not modify the License. You may add Your own attribution + notices within Derivative Works that You distribute, alongside + or as an addendum to the NOTICE text from the Work, provided + that such additional attribution notices cannot be construed + as modifying the License. + + You may add Your own copyright statement to Your modifications and + may provide additional or different license terms and conditions + for use, reproduction, or distribution of Your modifications, or + for any such Derivative Works as a whole, provided Your use, + reproduction, and distribution of the Work otherwise complies with + the conditions stated in this License. + +5. Submission of Contributions. Unless You explicitly state otherwise, + any Contribution intentionally submitted for inclusion in the Work + by You to the Licensor shall be under the terms and conditions of + this License, without any additional terms or conditions. + Notwithstanding the above, nothing herein shall supersede or modify + the terms of any separate license agreement you may have executed + with Licensor regarding such Contributions. + +6. Trademarks. This License does not grant permission to use the trade + names, trademarks, service marks, or product names of the Licensor, + except as required for reasonable and customary use in describing the + origin of the Work and reproducing the content of the NOTICE file. + +7. Disclaimer of Warranty. Unless required by applicable law or + agreed to in writing, Licensor provides the Work (and each + Contributor provides its Contributions) on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or + implied, including, without limitation, any warranties or conditions + of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A + PARTICULAR PURPOSE. You are solely responsible for determining the + appropriateness of using or redistributing the Work and assume any + risks associated with Your exercise of permissions under this License. + +8. Limitation of Liability. In no event and under no legal theory, + whether in tort (including negligence), contract, or otherwise, + unless required by applicable law (such as deliberate and grossly + negligent acts) or agreed to in writing, shall any Contributor be + liable to You for damages, including any direct, indirect, special, + incidental, or consequential damages of any character arising as a + result of this License or out of the use or inability to use the + Work (including but not limited to damages for loss of goodwill, + work stoppage, computer failure or malfunction, or any and all + other commercial damages or losses), even if such Contributor + has been advised of the possibility of such damages. + +9. Accepting Warranty or Additional Liability. While redistributing + the Work or Derivative Works thereof, You may choose to offer, + and charge a fee for, acceptance of support, warranty, indemnity, + or other liability obligations and/or rights consistent with this + License. However, in accepting such obligations, You may act only + on Your own behalf and on Your sole responsibility, not on behalf + of any other Contributor, and only if You agree to indemnify, + defend, and hold each Contributor harmless for any liability + incurred by, or claims asserted against, such Contributor by reason + of your accepting any such warranty or additional liability. + +END OF TERMS AND CONDITIONS diff --git a/LICENSE-MIT b/LICENSE-MIT new file mode 100644 index 0000000..31aa793 --- /dev/null +++ b/LICENSE-MIT @@ -0,0 +1,23 @@ +Permission is hereby granted, free of charge, to any +person obtaining a copy of this software and associated +documentation files (the "Software"), to deal in the +Software without restriction, including without +limitation the rights to use, copy, modify, merge, +publish, distribute, sublicense, and/or sell copies of +the Software, and to permit persons to whom the Software +is furnished to do so, subject to the following +conditions: + +The above copyright notice and this permission notice +shall be included in all copies or substantial portions +of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF +ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED +TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A +PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT +SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR +IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. diff --git a/src/find_fde/mod.rs b/src/find_fde/mod.rs new file mode 100644 index 0000000..ec0b658 --- /dev/null +++ b/src/find_fde/mod.rs @@ -0,0 +1,33 @@ +mod phdr; +mod registry; + +use crate::util::*; +use gimli::{BaseAddresses, EhFrame, FrameDescriptionEntry}; + +pub struct FDESearchResult { + pub fde: FrameDescriptionEntry, + pub bases: BaseAddresses, + pub eh_frame: EhFrame, +} + +pub trait FDEFinder { + fn find_fde(&self, pc: usize) -> Option; +} + +pub struct GlobalFinder(()); + +impl FDEFinder for GlobalFinder { + fn find_fde(&self, pc: usize) -> Option { + if let Some(v) = registry::get_finder().find_fde(pc) { + return Some(v); + } + if let Some(v) = phdr::get_finder().find_fde(pc) { + return Some(v); + } + None + } +} + +pub fn get_finder() -> &'static GlobalFinder { + &GlobalFinder(()) +} diff --git a/src/find_fde/phdr.rs b/src/find_fde/phdr.rs new file mode 100644 index 0000000..deacd3a --- /dev/null +++ b/src/find_fde/phdr.rs @@ -0,0 +1,130 @@ +use super::FDESearchResult; +use crate::util::{deref_pointer, get_unlimited_slice}; +use core::mem; +use core::slice; +use gimli::{BaseAddresses, EhFrame, EhFrameHdr, NativeEndian, UnwindSection}; +use libc::{c_int, c_void, dl_iterate_phdr, dl_phdr_info, PT_DYNAMIC, PT_GNU_EH_FRAME, PT_LOAD}; + +struct CallbackData { + pc: usize, + result: Option, +} + +pub struct PhdrFinder(()); + +pub fn get_finder() -> &'static PhdrFinder { + &PhdrFinder(()) +} + +impl super::FDEFinder for PhdrFinder { + fn find_fde(&self, pc: usize) -> Option { + let mut data = CallbackData { pc, result: None }; + unsafe { dl_iterate_phdr(Some(phdr_callback), &mut data as *mut CallbackData as _) }; + data.result + } +} + +unsafe extern "C" fn phdr_callback( + info: *mut dl_phdr_info, + _size: usize, + data: *mut c_void, +) -> c_int { + let data = &mut *(data as *mut CallbackData); + let phdrs = slice::from_raw_parts((*info).dlpi_phdr, (*info).dlpi_phnum as usize); + + let mut text = None; + let mut eh_frame_hdr = None; + let mut dynamic = None; + + for phdr in phdrs { + let start = (*info).dlpi_addr + phdr.p_vaddr; + match phdr.p_type { + PT_LOAD => { + let end = start + phdr.p_memsz; + let range = start..end; + if range.contains(&(data.pc as _)) { + text = Some(range); + } + } + PT_GNU_EH_FRAME => { + eh_frame_hdr = Some(start); + } + PT_DYNAMIC => { + dynamic = Some(start); + } + _ => (), + } + } + + let text = match text { + Some(v) => v, + None => return 0, + }; + + let eh_frame_hdr = match eh_frame_hdr { + Some(v) => v, + None => return 0, + }; + + let mut bases = BaseAddresses::default() + .set_eh_frame_hdr(eh_frame_hdr as _) + .set_text(text.start as _); + + // Find the GOT section. + if let Some(start) = dynamic { + const DT_NULL: usize = 0; + const DT_PLTGOT: usize = 3; + + let mut tags = start as *const [usize; 2]; + let mut tag = *tags; + while tag[0] != DT_NULL { + if tag[0] == DT_PLTGOT { + bases = bases.set_got(tag[1] as _); + break; + } + tags = tags.add(1); + tag = *tags; + } + } + + // Parse .eh_frame_hdr section. + let eh_frame_hdr = EhFrameHdr::new( + get_unlimited_slice(eh_frame_hdr as usize as _), + NativeEndian, + ) + .parse(&bases, mem::size_of::() as _); + let eh_frame_hdr = match eh_frame_hdr { + Ok(v) => v, + Err(_) => return 0, + }; + + let eh_frame = deref_pointer(eh_frame_hdr.eh_frame_ptr()); + bases = bases.set_eh_frame(eh_frame as _); + let eh_frame = EhFrame::new(get_unlimited_slice(eh_frame as usize as _), NativeEndian); + + // Use binary search table for address if available. + if let Some(table) = eh_frame_hdr.table() { + if let Ok(fde) = + table.fde_for_address(&eh_frame, &bases, data.pc as _, EhFrame::cie_from_offset) + { + data.result = Some(FDESearchResult { + fde, + bases, + eh_frame, + }); + return 1; + } + } + + // Otherwise do the linear search. + if let Ok(fde) = eh_frame.fde_for_address(&bases, data.pc as _, EhFrame::cie_from_offset) { + data.result = Some(FDESearchResult { + fde, + bases, + eh_frame, + }); + return 1; + } + + 0 +} diff --git a/src/find_fde/registry.rs b/src/find_fde/registry.rs new file mode 100644 index 0000000..f63b026 --- /dev/null +++ b/src/find_fde/registry.rs @@ -0,0 +1,205 @@ +use super::FDESearchResult; +use crate::util::get_unlimited_slice; +use core::mem::MaybeUninit; +use core::ptr; +use gimli::{BaseAddresses, EhFrame, NativeEndian, UnwindSection}; +use libc::c_void; +use once_cell::sync::Lazy; +use std::sync::Mutex; + +enum Table { + Single(*const c_void), + Multiple(*const *const c_void), +} + +struct Object { + next: *mut Object, + tbase: usize, + dbase: usize, + table: Table, +} + +struct RegistryInner { + object: *mut Object, +} + +unsafe impl Send for RegistryInner {} + +pub struct Registry { + inner: Mutex, +} + +pub fn get_finder() -> &'static Registry { + static LAZY: Lazy = Lazy::new(|| Registry { + inner: Mutex::new(RegistryInner { + object: ptr::null_mut(), + }), + }); + &*LAZY +} + +impl super::FDEFinder for Registry { + fn find_fde(&self, pc: usize) -> Option { + let guard = get_finder().inner.lock().unwrap(); + let mut cur = guard.object; + + unsafe { + while !cur.is_null() { + let bases = BaseAddresses::default() + .set_text((*cur).tbase as _) + .set_got((*cur).dbase as _); + match (*cur).table { + Table::Single(addr) => { + let eh_frame = EhFrame::new(get_unlimited_slice(addr as _), NativeEndian); + let bases = bases.clone().set_eh_frame(addr as usize as _); + if let Ok(fde) = + eh_frame.fde_for_address(&bases, pc as _, EhFrame::cie_from_offset) + { + return Some(FDESearchResult { + fde, + bases, + eh_frame, + }); + } + } + Table::Multiple(mut addrs) => { + let mut addr = *addrs; + while !addr.is_null() { + let eh_frame = + EhFrame::new(get_unlimited_slice(addr as _), NativeEndian); + let bases = bases.clone().set_eh_frame(addr as usize as _); + if let Ok(fde) = + eh_frame.fde_for_address(&bases, pc as _, EhFrame::cie_from_offset) + { + return Some(FDESearchResult { + fde, + bases, + eh_frame, + }); + } + + addrs = addrs.add(1); + addr = *addrs; + } + } + } + + cur = (*cur).next; + } + } + + None + } +} + +#[no_mangle] +unsafe extern "C" fn __register_frame_info_bases( + begin: *const c_void, + ob: *mut Object, + tbase: *const c_void, + dbase: *const c_void, +) { + if begin.is_null() { + return; + } + + ob.write(Object { + next: core::ptr::null_mut(), + tbase: tbase as _, + dbase: dbase as _, + table: Table::Single(begin), + }); + + let mut guard = get_finder().inner.lock().unwrap(); + (*ob).next = guard.object; + guard.object = ob; +} + +#[no_mangle] +unsafe extern "C" fn __register_frame_info(begin: *const c_void, ob: *mut Object) { + __register_frame_info_bases(begin, ob, core::ptr::null_mut(), core::ptr::null_mut()); +} + +#[no_mangle] +unsafe extern "C" fn __register_frame(begin: *const c_void) { + if begin.is_null() { + return; + } + + let storage = Box::into_raw(Box::new(MaybeUninit::::uninit())) as *mut Object; + __register_frame_info(begin, storage); +} + +#[no_mangle] +unsafe extern "C" fn __register_frame_info_table_bases( + begin: *const c_void, + ob: *mut Object, + tbase: *const c_void, + dbase: *const c_void, +) { + ob.write(Object { + next: core::ptr::null_mut(), + tbase: tbase as _, + dbase: dbase as _, + table: Table::Multiple(begin as _), + }); + + let mut guard = get_finder().inner.lock().unwrap(); + (*ob).next = guard.object; + guard.object = ob; +} + +#[no_mangle] +unsafe extern "C" fn __register_frame_info_table(begin: *const c_void, ob: *mut Object) { + __register_frame_info_table_bases(begin, ob, core::ptr::null_mut(), core::ptr::null_mut()); +} + +#[no_mangle] +unsafe extern "C" fn __register_frame_table(begin: *const c_void) { + if begin.is_null() { + return; + } + + let storage = Box::into_raw(Box::new(MaybeUninit::::uninit())) as *mut Object; + __register_frame_info_table(begin, storage); +} + +#[no_mangle] +unsafe extern "C" fn __deregister_frame_info_bases(begin: *const c_void) -> *mut Object { + if begin.is_null() { + return core::ptr::null_mut(); + } + + let mut guard = get_finder().inner.lock().unwrap(); + let mut prev = &mut guard.object; + let mut cur = *prev; + + while !cur.is_null() { + let found = match (*cur).table { + Table::Single(addr) => addr == begin, + _ => false, + }; + if found { + *prev = (*cur).next; + return cur; + } + prev = &mut (*cur).next; + cur = *prev; + } + + core::ptr::null_mut() +} + +#[no_mangle] +unsafe extern "C" fn __deregister_frame_info(begin: *const c_void) -> *mut Object { + __deregister_frame_info_bases(begin) +} + +#[no_mangle] +unsafe extern "C" fn __deregister_frame(begin: *const c_void) { + if begin.is_null() { + return; + } + let storage = __deregister_frame_info(begin); + drop(Box::from_raw(storage as *mut MaybeUninit)) +} diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..04b16d8 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,2 @@ +mod find_fde; +mod util; diff --git a/src/util.rs b/src/util.rs new file mode 100644 index 0000000..7e9687f --- /dev/null +++ b/src/util.rs @@ -0,0 +1,18 @@ +use gimli::{EndianSlice, NativeEndian, Pointer}; + +pub type StaticSlice = EndianSlice<'static, NativeEndian>; + +pub unsafe fn get_unlimited_slice<'a>(start: *const u8) -> &'a [u8] { + // Create the largest possible slice for this address. + let start = start as usize; + let end = start.saturating_add(isize::MAX as _); + let len = end - start; + core::slice::from_raw_parts(start as *const _, len) +} + +pub unsafe fn deref_pointer(ptr: Pointer) -> usize { + match ptr { + Pointer::Direct(x) => x as _, + Pointer::Indirect(x) => *(x as *const _), + } +}