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-rw-r--r--Userland/Libraries/LibC/elf.h3
-rw-r--r--Userland/Libraries/LibELF/DynamicLinker.cpp8
-rw-r--r--Userland/Libraries/LibELF/DynamicLoader.cpp46
-rw-r--r--Userland/Libraries/LibELF/DynamicObject.cpp5
-rw-r--r--Userland/Libraries/LibELF/DynamicObject.h2
-rw-r--r--Userland/Libraries/LibELF/Image.cpp2
6 files changed, 56 insertions, 10 deletions
diff --git a/Userland/Libraries/LibC/elf.h b/Userland/Libraries/LibC/elf.h
index d61dc831d2..d43ec0e859 100644
--- a/Userland/Libraries/LibC/elf.h
+++ b/Userland/Libraries/LibC/elf.h
@@ -381,6 +381,7 @@ typedef struct {
#define STT_SECTION 3 /* section */
#define STT_FILE 4 /* file */
#define STT_TLS 6 /* thread local storage */
+#define STT_GNU_IFUNC 10
#define STT_LOPROC 13 /* reserved range for processor */
#define STT_HIPROC 15 /* specific symbol types */
@@ -812,6 +813,7 @@ struct elf_args {
#define R_386_RELATIVE 8 /* Base address + Addned */
#define R_386_TLS_TPOFF 14 /* Negative offset into the static TLS storage */
#define R_386_TLS_TPOFF32 37
+#define R_386_IRELATIVE 42 /* PLT entry resolved indirectly at runtime */
#define R_X86_64_NONE 0
#define R_X86_64_64 1
@@ -819,3 +821,4 @@ struct elf_args {
#define R_X86_64_JUMP_SLOT 7
#define R_X86_64_RELATIVE 8
#define R_X86_64_TPOFF64 18
+#define R_X86_64_IRELATIVE 37
diff --git a/Userland/Libraries/LibELF/DynamicLinker.cpp b/Userland/Libraries/LibELF/DynamicLinker.cpp
index 499632578b..d72ea3df80 100644
--- a/Userland/Libraries/LibELF/DynamicLinker.cpp
+++ b/Userland/Libraries/LibELF/DynamicLinker.cpp
@@ -469,10 +469,12 @@ static Result<void*, DlErrorMessage> __dlsym(void* handle, char const* symbol_na
symbol = DynamicLinker::lookup_global_symbol(symbol_name);
}
- if (symbol.has_value())
- return symbol.value().address.as_ptr();
+ if (!symbol.has_value())
+ return DlErrorMessage { String::formatted("Symbol {} not found", symbol_name) };
- return DlErrorMessage { String::formatted("Symbol {} not found", symbol_name) };
+ if (symbol.value().type == STT_GNU_IFUNC)
+ return (void*)reinterpret_cast<DynamicObject::IfuncResolver>(symbol.value().address.as_ptr())();
+ return symbol.value().address.as_ptr();
}
static Result<void, DlErrorMessage> __dladdr(void* addr, Dl_info* info)
diff --git a/Userland/Libraries/LibELF/DynamicLoader.cpp b/Userland/Libraries/LibELF/DynamicLoader.cpp
index 6a78df5af5..c57e5b2ed9 100644
--- a/Userland/Libraries/LibELF/DynamicLoader.cpp
+++ b/Userland/Libraries/LibELF/DynamicLoader.cpp
@@ -2,6 +2,7 @@
* Copyright (c) 2019-2020, Andrew Kaster <akaster@serenityos.org>
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2022, Daniel Bertalan <dani@danielbertalan.dev>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@@ -177,6 +178,15 @@ bool DynamicLoader::load_stage_2(unsigned flags)
return false;
}
}
+ } else {
+ // .text needs to be executable while we process relocations because it might contain IFUNC resolvers.
+ // We don't allow IFUNC resolvers in objects with textrels.
+ for (auto& text_segment : m_text_segments) {
+ if (mprotect(text_segment.address().as_ptr(), text_segment.size(), PROT_READ | PROT_EXEC) < 0) {
+ perror("mprotect .text: PROT_READ | PROT_EXEC");
+ return false;
+ }
+ }
}
do_main_relocations();
return true;
@@ -210,9 +220,12 @@ Result<NonnullRefPtr<DynamicObject>, DlErrorMessage> DynamicLoader::load_stage_3
setup_plt_trampoline();
}
- for (auto& text_segment : m_text_segments) {
- if (mprotect(text_segment.address().as_ptr(), text_segment.size(), PROT_READ | PROT_EXEC) < 0) {
- return DlErrorMessage { String::formatted("mprotect .text: PROT_READ | PROT_EXEC: {}", strerror(errno)) };
+ if (m_dynamic_object->has_text_relocations()) {
+ // If we don't have textrels, .text has already been made executable by this point in load_stage_2.
+ for (auto& text_segment : m_text_segments) {
+ if (mprotect(text_segment.address().as_ptr(), text_segment.size(), PROT_READ | PROT_EXEC) < 0) {
+ return DlErrorMessage { String::formatted("mprotect .text: PROT_READ | PROT_EXEC: {}", strerror(errno)) };
+ }
}
}
@@ -411,6 +424,10 @@ DynamicLoader::RelocationResult DynamicLoader::do_relocation(const ELF::DynamicO
else
patch_ptr = (FlatPtr*)(FlatPtr)relocation.offset();
+ auto call_ifunc_resolver = [](VirtualAddress address) {
+ return VirtualAddress { reinterpret_cast<DynamicObject::IfuncResolver>(address.get())() };
+ };
+
switch (relocation.type()) {
#if ARCH(I386)
case R_386_NONE:
@@ -438,6 +455,8 @@ DynamicLoader::RelocationResult DynamicLoader::do_relocation(const ELF::DynamicO
*patch_ptr = symbol_address.get() + relocation.addend();
else
*patch_ptr += symbol_address.get();
+ if (res.value().type == STT_GNU_IFUNC)
+ *patch_ptr = call_ifunc_resolver(VirtualAddress { *patch_ptr }).get();
break;
}
#if ARCH(I386)
@@ -467,8 +486,11 @@ DynamicLoader::RelocationResult DynamicLoader::do_relocation(const ELF::DynamicO
}
symbol_location = VirtualAddress { (FlatPtr)0 };
- } else
+ } else {
symbol_location = res.value().address;
+ if (res.value().type == STT_GNU_IFUNC)
+ symbol_location = call_ifunc_resolver(symbol_location);
+ }
VERIFY(symbol_location != m_dynamic_object->base_address());
*patch_ptr = symbol_location.get();
break;
@@ -500,6 +522,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_relocation(const ELF::DynamicO
auto res = lookup_symbol(symbol);
if (!res.has_value())
break;
+ VERIFY(symbol.type() != STT_GNU_IFUNC);
symbol_value = res.value().value;
dynamic_object_of_symbol = res.value().dynamic_object;
} else {
@@ -529,6 +552,19 @@ DynamicLoader::RelocationResult DynamicLoader::do_relocation(const ELF::DynamicO
}
break;
}
+#if ARCH(I386)
+ case R_386_IRELATIVE: {
+#else
+ case R_X86_64_IRELATIVE: {
+#endif
+ VirtualAddress resolver;
+ if (relocation.addend_used())
+ resolver = m_dynamic_object->base_address().offset(relocation.addend());
+ else
+ resolver = m_dynamic_object->base_address().offset(*patch_ptr);
+ *patch_ptr = call_ifunc_resolver(resolver).get();
+ break;
+ }
default:
// Raise the alarm! Someone needs to implement this relocation type
dbgln("Found a new exciting relocation type {}", relocation.type());
@@ -635,7 +671,7 @@ Optional<DynamicObject::SymbolLookupResult> DynamicLoader::lookup_symbol(const E
if (symbol.is_undefined() || symbol.bind() == STB_WEAK)
return DynamicLinker::lookup_global_symbol(symbol.name());
- return DynamicObject::SymbolLookupResult { symbol.value(), symbol.size(), symbol.address(), symbol.bind(), &symbol.object() };
+ return DynamicObject::SymbolLookupResult { symbol.value(), symbol.size(), symbol.address(), symbol.bind(), symbol.type(), &symbol.object() };
}
} // end namespace ELF
diff --git a/Userland/Libraries/LibELF/DynamicObject.cpp b/Userland/Libraries/LibELF/DynamicObject.cpp
index 2b0f6b42bb..a65ee51b53 100644
--- a/Userland/Libraries/LibELF/DynamicObject.cpp
+++ b/Userland/Libraries/LibELF/DynamicObject.cpp
@@ -471,7 +471,7 @@ auto DynamicObject::lookup_symbol(HashSymbol const& symbol) const -> Optional<Sy
auto symbol_result = result.value();
if (symbol_result.is_undefined())
return {};
- return SymbolLookupResult { symbol_result.value(), symbol_result.size(), symbol_result.address(), symbol_result.bind(), this };
+ return SymbolLookupResult { symbol_result.value(), symbol_result.size(), symbol_result.address(), symbol_result.bind(), symbol_result.type(), this };
}
NonnullRefPtr<DynamicObject> DynamicObject::create(String const& filename, VirtualAddress base_address, VirtualAddress dynamic_section_address)
@@ -495,6 +495,9 @@ VirtualAddress DynamicObject::patch_plt_entry(u32 relocation_offset)
auto result = DynamicLoader::lookup_symbol(symbol);
if (result.has_value()) {
symbol_location = result.value().address;
+
+ if (result.value().type == STT_GNU_IFUNC)
+ symbol_location = VirtualAddress { reinterpret_cast<IfuncResolver>(symbol_location.get())() };
} else if (symbol.bind() != STB_WEAK) {
dbgln("did not find symbol while doing relocations for library {}: {}", m_filename, symbol.name());
VERIFY_NOT_REACHED();
diff --git a/Userland/Libraries/LibELF/DynamicObject.h b/Userland/Libraries/LibELF/DynamicObject.h
index 6161a6c568..2a60c16ad0 100644
--- a/Userland/Libraries/LibELF/DynamicObject.h
+++ b/Userland/Libraries/LibELF/DynamicObject.h
@@ -255,6 +255,7 @@ public:
Symbol symbol(unsigned) const;
typedef void (*InitializationFunction)();
+ typedef ElfW(Addr) (*IfuncResolver)();
bool has_init_section() const { return m_init_offset != 0; }
bool has_init_array_section() const { return m_init_array_offset != 0; }
@@ -322,6 +323,7 @@ public:
size_t size { 0 };
VirtualAddress address;
unsigned bind { STB_LOCAL };
+ unsigned type { STT_FUNC };
const ELF::DynamicObject* dynamic_object { nullptr }; // The object in which the symbol is defined
};
diff --git a/Userland/Libraries/LibELF/Image.cpp b/Userland/Libraries/LibELF/Image.cpp
index 694a7721f3..da79f41f65 100644
--- a/Userland/Libraries/LibELF/Image.cpp
+++ b/Userland/Libraries/LibELF/Image.cpp
@@ -362,7 +362,7 @@ Optional<Image::Symbol> Image::find_demangled_function(StringView name) const
{
Optional<Image::Symbol> found;
for_each_symbol([&](Image::Symbol const& symbol) {
- if (symbol.type() != STT_FUNC)
+ if (symbol.type() != STT_FUNC && symbol.type() != STT_GNU_IFUNC)
return IterationDecision::Continue;
if (symbol.is_undefined())
return IterationDecision::Continue;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 18:33:18 +0000