From: Shiz Last-Updated: Sun, 20 May 2018 00:05:00 +0200 Subject: [PATCH] Add support for static PIE executables Note that static PIE binaries are reported as dynamically linked by file(1): $ rustc -C target-feature=+crt-static hello_world.rb $ file hello_world ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically \ linked, not stripped, with debug_info In addition, ldd(1) reports that it's linked with ldd, as it can't find any dependencies except itself loaded into the process: $ ldd hello_world ldd (0x237fcc81000) Static PIE binaries are dynamic binaries without a loader or any DT_NEEDED entries. The important is that they do not depend on libc or any other system library, just like static binaries, but more secure. $ readelf -d hello_world Dynamic section at offset 0x2de40 contains 17 entries: Tag Type Name/Value 0x0000000000000010 (SYMBOLIC) 0x0 0x000000000000000c (INIT) 0x17a0 0x000000000000000d (FINI) 0x2003c 0x000000006ffffef5 (GNU_HASH) 0x1c8 0x0000000000000005 (STRTAB) 0x278 0x0000000000000006 (SYMTAB) 0x200 0x000000000000000a (STRSZ) 60 (bytes) 0x000000000000000b (SYMENT) 24 (bytes) 0x0000000000000015 (DEBUG) 0x0 0x0000000000000003 (PLTGOT) 0x22df90 0x0000000000000007 (RELA) 0x2b8 0x0000000000000008 (RELASZ) 5352 (bytes) 0x0000000000000009 (RELAENT) 24 (bytes) 0x0000000000000018 (BIND_NOW) 0x000000006ffffffb (FLAGS_1) Flags: NOW PIE 0x000000006ffffff9 (RELACOUNT) 223 0x0000000000000000 (NULL) 0x0 --- a/src/librustc_target/spec/linux_musl_base.rs +++ b/src/librustc_target/spec/linux_musl_base.rs @@ -25,5 +25,8 @@ // These targets allow the user to choose between static and dynamic linking. base.crt_static_respected = true; + // Static position-independent executables are supported. + base.static_position_independent_executables = true; + base } --- a/src/librustc_target/spec/mod.rs +++ b/src/librustc_target/spec/mod.rs @@ -576,6 +576,8 @@ /// the functions in the executable are not randomized and can be used /// during an exploit of a vulnerability in any code. pub position_independent_executables: bool, + /// As above, but also support for static position independent executables. + pub static_position_independent_executables: bool, /// Determines if the target always requires using the PLT for indirect /// library calls or not. This controls the default value of the `-Z plt` flag. pub needs_plt: bool, @@ -729,8 +729,9 @@ has_rpath: false, no_default_libraries: true, position_independent_executables: false, + static_position_independent_executables: false, needs_plt: false, relro_level: RelroLevel::None, pre_link_objects_exe: Vec::new(), pre_link_objects_dll: Vec::new(), post_link_objects: Vec::new(), --- a/src/librustc_codegen_ssa/back/link.rs +++ b/src/librustc_codegen_ssa/back/link.rs @@ -1058,12 +1058,7 @@ let mut position_independent_executable = false; if t.options.position_independent_executables { - let empty_vec = Vec::new(); - let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec); - let more_args = &sess.opts.cg.link_arg; - let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter()); - - if is_pic(sess) && !sess.crt_static() && !args.any(|x| *x == "-static") { + if is_pic(sess) && (!sess.crt_static() || t.options.static_position_independent_executables) { position_independent_executable = true; } } --- a/src/librustc_target/spec/mod.rs +++ b/src/librustc_target/spec/mod.rs @@ -1023,8 +1023,9 @@ key!(has_rpath, bool); key!(no_default_libraries, bool); key!(position_independent_executables, bool); + key!(static_position_independent_executables, bool); key!(needs_plt, bool); key!(relro_level, RelroLevel)?; key!(archive_format); key!(allow_asm, bool); key!(custom_unwind_resume, bool); @@ -1233,8 +1233,9 @@ target_option_val!(has_rpath); target_option_val!(no_default_libraries); target_option_val!(position_independent_executables); + target_option_val!(static_position_independent_executables); target_option_val!(needs_plt); target_option_val!(relro_level); target_option_val!(archive_format); target_option_val!(allow_asm); target_option_val!(custom_unwind_resume);