Hi,
Could you please run 'readelf -W -l ' against this executable? Maybe it is
a statically linked executable.
It is determined by this expression:
bool is_statically_linked() { return !_is_dynamically_linked_executable &&
_ehdr.e_entry; }
and _is_dynamically_linked_executable is set to true if there is PT_INTERP
header.
On Sunday, September 10, 2023 at 5:24:43 AM UTC-4 n...@scylladb.com wrote:
> When I try to run the default scripts/build (the Lua shell) on Fedora 38
> (with https://github.com/cloudius-systems/osv/pull/1257),
> I get the error message added in this patch:
>
> $ scripts/run.py
> OSv v0.57.0-61-g72ed41c6
> eth0: 192.168.122.15
> Booted up in 156.82 ms
> Cmdline: /cli
>
> Statically linked executables are not supported yet!
>
> Why does it think the Lua executable is statically linked?
>
> --
> Nadav Har'El
> n...@scylladb.com
>
>
> On Thu, Aug 31, 2023 at 9:51 AM Commit Bot <b...@cloudius-systems.com>
> wrote:
>
>> From: Nadav Har'El <n...@scylladb.com>
>> Committer: Nadav Har'El <n...@scylladb.com>
>> Branch: master
>>
>> Merge 'Dynamic linker: support loading and processing statically linked
>> executables' from WALDEMAR KOZACZUK
>>
>> The two commits provide necessary modifications to the OSv dynamic linker
>> to support loading and processing statically linked executables.
>>
>> Please note these changes are NOT enough to make OSv run statically
>> linked executables.
>>
>> Closes #1253
>>
>> * github.com:cloudius-systems/osv:
>> dynamic linker: support loading and processing static ELF
>> dynamic linker: rename is_executable to is_dynamically_linked_executable
>>
>> ---
>> diff --git a/arch/aarch64/arch-elf.cc b/arch/aarch64/arch-elf.cc
>> --- a/arch/aarch64/arch-elf.cc
>> +++ b/arch/aarch64/arch-elf.cc
>> @@ -66,7 +66,7 @@ bool object::arch_relocate_rela(u32 type, u32 sym, void
>> *addr,
>> if (sym) {
>> auto sm = symbol(sym);
>> ulong tls_offset;
>> - if (sm.obj->is_executable()) {
>> + if (sm.obj->is_dynamically_linked_executable()) {
>> // If this is an executable (pie or position-dependant
>> one)
>> // then the variable is located in the reserved slot of
>> the TLS
>> // right where the kernel TLS lives
>> @@ -119,7 +119,7 @@ void object::arch_relocate_tls_desc(u32 sym, void
>> *addr, Elf64_Sxword addend)
>> ulong tls_offset;
>> if (sym) {
>> auto sm = symbol(sym);
>> - if (sm.obj->is_executable() || sm.obj->is_core()) {
>> + if (sm.obj->is_dynamically_linked_executable() ||
>> sm.obj->is_core()) {
>> // If this is an executable (pie or position-dependant one)
>> // then the variable is located in the reserved slot of the
>> TLS
>> // right where the kernel TLS lives
>> @@ -163,7 +163,7 @@ void object::prepare_initial_tls(void* buffer, size_t
>> size,
>>
>> void object::prepare_local_tls(std::vector<ptrdiff_t>& offsets)
>> {
>> - if (!_static_tls && !is_executable()) {
>> + if (!_static_tls && !is_dynamically_linked_executable()) {
>> return;
>> }
>>
>> diff --git a/arch/aarch64/arch-switch.hh b/arch/aarch64/arch-switch.hh
>> --- a/arch/aarch64/arch-switch.hh
>> +++ b/arch/aarch64/arch-switch.hh
>> @@ -120,7 +120,7 @@ void thread::setup_tcb()
>> assert(obj);
>> user_tls_size = obj->initial_tls_size();
>> user_tls_data = obj->initial_tls();
>> - if (obj->is_executable()) {
>> + if (obj->is_dynamically_linked_executable()) {
>> executable_tls_size = obj->get_tls_size();
>> }
>> }
>> diff --git a/arch/x64/arch-elf.cc b/arch/x64/arch-elf.cc
>> --- a/arch/x64/arch-elf.cc
>> +++ b/arch/x64/arch-elf.cc
>> @@ -138,7 +138,7 @@ bool object::arch_relocate_rela(u32 type, u32 sym,
>> void *addr,
>> if (sym) {
>> auto sm = symbol(sym);
>> ulong tls_offset;
>> - if (sm.obj->is_executable()) {
>> + if (sm.obj->is_dynamically_linked_executable()) {
>> // If this is an executable (pie or position-dependant
>> one)
>> // then the variable is located in the reserved slot of
>> the TLS
>> // right where the kernel TLS lives
>> @@ -202,7 +202,7 @@ void object::prepare_initial_tls(void* buffer, size_t
>> size,
>>
>> void object::prepare_local_tls(std::vector<ptrdiff_t>& offsets)
>> {
>> - if (!_static_tls && !is_executable()) {
>> + if (!_static_tls && !is_dynamically_linked_executable()) {
>> return;
>> }
>>
>> diff --git a/arch/x64/arch-switch.hh b/arch/x64/arch-switch.hh
>> --- a/arch/x64/arch-switch.hh
>> +++ b/arch/x64/arch-switch.hh
>> @@ -210,7 +210,7 @@ void thread::setup_tcb()
>> assert(obj);
>> user_tls_size = obj->initial_tls_size();
>> user_tls_data = obj->initial_tls();
>> - if (obj->is_executable()) {
>> + if (obj->is_dynamically_linked_executable()) {
>> executable_tls_size = obj->get_tls_size();
>> aligned_executable_tls_size = obj->get_aligned_tls_size();
>> }
>> diff --git a/core/elf.cc b/core/elf.cc
>> --- a/core/elf.cc
>> +++ b/core/elf.cc
>> @@ -123,7 +123,7 @@ object::object(program& prog, std::string pathname)
>> , _initial_tls_size(0)
>> , _dynamic_table(nullptr)
>> , _module_index(_prog.register_dtv(this))
>> - , _is_executable(false)
>> + , _is_dynamically_linked_executable(false)
>> , _init_called(false)
>> , _eh_frame(0)
>> , _visibility_thread(nullptr)
>> @@ -249,9 +249,6 @@ const char * object::symbol_name(const Elf64_Sym *
>> sym) {
>> }
>>
>> void* object::entry_point() const {
>> - if (!_is_executable) {
>> - return nullptr;
>> - }
>> return _base + _ehdr.e_entry;
>> }
>>
>> @@ -366,13 +363,13 @@ void object::set_base(void* base)
>> [](const Elf64_Phdr* a, const Elf64_Phdr*
>> b)
>> { return a->p_vaddr < b->p_vaddr; });
>>
>> - if (!is_core() && is_non_pie_executable()) {
>> - // Verify non-PIE executable does not collide with the kernel
>> + if (!is_core() && !is_pic()) {
>> + // Verify non-PIC executable ((aka position dependent)) does not
>> collide with the kernel
>> if (intersects_with_kernel(p->p_vaddr) ||
>> intersects_with_kernel(q->p_vaddr + q->p_memsz)) {
>> - abort("Non-PIE executable [%s] collides with kernel: [%p-%p]
>> !\n",
>> + abort("Non-PIC executable [%s] collides with kernel: [%p-%p]
>> !\n",
>> pathname().c_str(), p->p_vaddr, q->p_vaddr +
>> q->p_memsz);
>> }
>> - // Override the passed in value as the base for non-PIEs
>> (Position Dependant Executables)
>> + // Override the passed in value as the base for non-PICs
>> (Position Dependant Executables)
>> // needs to be set to 0 because all the addresses in it are
>> absolute
>> _base = 0x0;
>> } else {
>> @@ -484,7 +481,7 @@ void object::process_headers()
>> _dynamic_table = reinterpret_cast<Elf64_Dyn*>(_base +
>> phdr.p_vaddr);
>> break;
>> case PT_INTERP:
>> - _is_executable = true;
>> + _is_dynamically_linked_executable = true;
>> break;
>> case PT_NOTE: {
>> if (phdr.p_memsz < 16) {
>> @@ -536,10 +533,10 @@ void object::process_headers()
>> abort("Unknown p_type in executable %s: %d\n", pathname(),
>> phdr.p_type);
>> }
>> }
>> - if (!is_core() && _ehdr.e_type == ET_EXEC && !_is_executable) {
>> - abort("Statically linked executables are not supported!\n");
>> + if (!is_core() && is_statically_linked()) {
>> + abort("Statically linked executables are not supported yet!\n");
>> }
>> - if (_is_executable && _tls_segment) {
>> + if (_is_dynamically_linked_executable && _tls_segment) {
>> auto app_tls_size = get_aligned_tls_size();
>> ulong pie_static_tls_maximum_size = &_pie_static_tls_end -
>> &_pie_static_tls_start;
>> if (app_tls_size > pie_static_tls_maximum_size) {
>> @@ -600,6 +597,12 @@ void object::fix_permissions()
>> make_text_writable(false);
>> }
>>
>> + //Full RELRO applies to dynamically linked executables only
>> + if (is_statically_linked()) {
>> + return;
>> + }
>> +
>> + //Process GNU_RELRO segments only to make GOT and others read-only
>> for (auto&& phdr : _phdrs) {
>> if (phdr.p_type != PT_GNU_RELRO)
>> continue;
>> @@ -888,6 +891,9 @@ constexpr Elf64_Versym old_version_symbol_mask =
>> Elf64_Versym(1) << 15;
>>
>> Elf64_Sym* object::lookup_symbol_old(const char* name)
>> {
>> + if (!dynamic_exists(DT_SYMTAB)) {
>> + return nullptr;
>> + }
>> auto symtab = dynamic_ptr<Elf64_Sym>(DT_SYMTAB);
>> auto strtab = dynamic_ptr<char>(DT_STRTAB);
>> auto hashtab = dynamic_ptr<Elf64_Word>(DT_HASH);
>> @@ -917,6 +923,9 @@ dl_new_hash(const char *s)
>>
>> Elf64_Sym* object::lookup_symbol_gnu(const char* name, bool self_lookup)
>> {
>> + if (!dynamic_exists(DT_SYMTAB)) {
>> + return nullptr;
>> + }
>> auto symtab = dynamic_ptr<Elf64_Sym>(DT_SYMTAB);
>> auto strtab = dynamic_ptr<char>(DT_STRTAB);
>> auto hashtab = dynamic_ptr<Elf64_Word>(DT_GNU_HASH);
>> @@ -1019,6 +1028,9 @@ dladdr_info object::lookup_addr(const void* addr)
>> if (addr < _base || addr >= _end) {
>> return ret;
>> }
>> + if (!dynamic_exists(DT_STRTAB)) {
>> + return ret;
>> + }
>> ret.fname = _pathname.c_str();
>> ret.base = _base;
>> auto strtab = dynamic_ptr<char>(DT_STRTAB);
>> @@ -1068,6 +1080,9 @@ static std::string dirname(std::string path)
>>
>> void object::load_needed(std::vector<std::shared_ptr<object>>&
>> loaded_objects)
>> {
>> + if (!dynamic_exists(DT_NEEDED)) {
>> + return;
>> + }
>> std::vector<std::string> rpath;
>>
>> std::string rpath_str;
>> @@ -1263,7 +1278,7 @@ void object::init_static_tls()
>> if (obj->is_core()) {
>> continue;
>> }
>> - if (obj->is_executable()) {
>> + if (obj->is_dynamically_linked_executable()) {
>> obj->prepare_local_tls(_initial_tls_offsets);
>> elf_debug("Initialized local-exec static TLS for %s\n",
>> obj->pathname().c_str());
>> }
>> @@ -1462,7 +1477,7 @@ program::load_object(std::string name,
>> std::vector<std::string> extra_path,
>> osv::rcu_dispose(old_modules);
>> ef->load_segments();
>> ef->process_headers();
>> - if (!ef->is_non_pie_executable())
>> + if (ef->is_pic())
>> _next_alloc = ef->end();
>> add_debugger_obj(ef.get());
>> loaded_objects.push_back(ef);
>> diff --git a/include/osv/elf.hh b/include/osv/elf.hh
>> --- a/include/osv/elf.hh
>> +++ b/include/osv/elf.hh
>> @@ -378,9 +378,9 @@ public:
>> size_t initial_tls_size() { return _initial_tls_size; }
>> void* initial_tls() { return _initial_tls.get(); }
>> void* get_tls_segment() { return _tls_segment; }
>> - bool is_non_pie_executable() { return _ehdr.e_type == ET_EXEC; }
>> + bool is_pic() { return _ehdr.e_type != ET_EXEC; }
>> std::vector<ptrdiff_t>& initial_tls_offsets() { return
>> _initial_tls_offsets; }
>> - bool is_executable() { return _is_executable; }
>> + bool is_dynamically_linked_executable() { return
>> _is_dynamically_linked_executable; }
>> ulong get_tls_size();
>> ulong get_aligned_tls_size();
>> void copy_local_tls(void* to_addr);
>> @@ -415,6 +415,7 @@ private:
>> void prepare_local_tls(std::vector<ptrdiff_t>& offsets);
>> void alloc_static_tls();
>> void make_text_writable(bool flag);
>> + bool is_statically_linked() { return
>> !_is_dynamically_linked_executable && _ehdr.e_entry; }
>> protected:
>> program& _prog;
>> std::string _pathname;
>> @@ -435,7 +436,7 @@ protected:
>> Elf64_Dyn* _dynamic_table;
>> ulong _module_index;
>> std::unique_ptr<char[]> _section_names_cache;
>> - bool _is_executable;
>> + bool _is_dynamically_linked_executable;
>> bool is_core();
>> bool _init_called;
>> void* _eh_frame;
>> @@ -462,7 +463,7 @@ protected:
>> bool arch_relocate_jump_slot(symbol_module& sym, void *addr,
>> Elf64_Sxword addend);
>> void arch_relocate_tls_desc(u32 sym, void *addr, Elf64_Sxword
>> addend);
>> size_t static_tls_end() {
>> - if (is_core() || is_executable()) {
>> + if (is_core() || _is_dynamically_linked_executable) {
>> return 0;
>> }
>> return _static_tls_offset + get_tls_size();
>>
>
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