Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

read/elf: add support for .dynamic sections #345

Merged
merged 1 commit into from
Aug 7, 2021
Merged

read/elf: add support for .dynamic sections #345

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
106 changes: 66 additions & 40 deletions examples/readobj.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -443,45 +443,7 @@ mod elf {
}
}

let proc = match elf.e_machine(endian) {
EM_SPARC => FLAGS_DT_SPARC,
EM_MIPS => FLAGS_DT_MIPS,
EM_ALPHA => FLAGS_DT_ALPHA,
EM_PPC => FLAGS_DT_PPC,
EM_PPC64 => FLAGS_DT_PPC64,
EM_IA_64 => FLAGS_DT_IA_64,
EM_ALTERA_NIOS2 => FLAGS_DT_NIOS2,
_ => &[],
};
for d in dynamic {
let tag = d.d_tag(endian).into();
let val = d.d_val(endian).into();
p.group("Dynamic", |p| {
if let Ok(tag) = tag.try_into() {
p.field_enums("Tag", tag, &[FLAGS_DT, proc]);
if tag == DT_NEEDED {
p.field_string(
"Value",
val,
val.try_into().ok().and_then(|val| dynstr.get(val).ok()),
);
} else {
p.field_hex("Value", val);
if tag == DT_FLAGS {
p.flags(val, 0, FLAGS_DF);
} else if tag == DT_FLAGS_1 {
p.flags(val, 0, FLAGS_DF_1);
}
}
} else {
p.field_hex("Tag", tag);
p.field_hex("Value", val);
}
});
if tag == DT_NULL.into() {
break;
}
}
print_dynamic(p, endian, elf, dynamic, dynstr);
}
}

Expand Down Expand Up @@ -541,14 +503,14 @@ mod elf {
SHT_REL => print_section_rel(p, endian, data, elf, sections, section),
SHT_RELA => print_section_rela(p, endian, data, elf, sections, section),
SHT_NOTE => print_section_notes(p, endian, data, elf, section),
SHT_DYNAMIC => print_section_dynamic(p, endian, data, elf, sections, section),
SHT_GROUP => print_section_group(p, endian, data, elf, sections, section),
SHT_HASH => print_hash(p, endian, data, elf, sections, section),
SHT_GNU_HASH => print_gnu_hash(p, endian, data, elf, sections, section),
SHT_GNU_VERDEF => print_gnu_verdef(p, endian, data, elf, sections, section),
SHT_GNU_VERNEED => print_gnu_verneed(p, endian, data, elf, sections, section),
SHT_GNU_VERSYM => print_gnu_versym(p, endian, data, elf, sections, section),
// TODO:
//SHT_DYNAMIC =>
//SHT_SHLIB =>
//SHT_INIT_ARRAY =>
//SHT_FINI_ARRAY =>
Expand Down Expand Up @@ -755,6 +717,22 @@ mod elf {
}
}

fn print_section_dynamic<Elf: FileHeader>(
p: &mut Printer<impl Write>,
endian: Elf::Endian,
data: &[u8],
elf: &Elf,
sections: &SectionTable<Elf>,
section: &Elf::SectionHeader,
) {
if let Ok(Some((dynamic, index))) = section.dynamic(endian, data) {
let strings = sections
.strings(endian, data, index)
.unwrap_or(StringTable::default());
print_dynamic(p, endian, elf, dynamic, strings);
}
}

fn print_section_group<Elf: FileHeader>(
p: &mut Printer<impl Write>,
endian: Elf::Endian,
Expand Down Expand Up @@ -810,6 +788,54 @@ mod elf {
}
}

fn print_dynamic<Elf: FileHeader>(
p: &mut Printer<impl Write>,
endian: Elf::Endian,
elf: &Elf,
dynamic: &[Elf::Dyn],
dynstr: StringTable,
) {
let proc = match elf.e_machine(endian) {
EM_SPARC => FLAGS_DT_SPARC,
EM_MIPS => FLAGS_DT_MIPS,
EM_ALPHA => FLAGS_DT_ALPHA,
EM_PPC => FLAGS_DT_PPC,
EM_PPC64 => FLAGS_DT_PPC64,
EM_IA_64 => FLAGS_DT_IA_64,
EM_ALTERA_NIOS2 => FLAGS_DT_NIOS2,
_ => &[],
};
for d in dynamic {
let tag = d.d_tag(endian).into();
let val = d.d_val(endian).into();
p.group("Dynamic", |p| {
if let Ok(tag) = tag.try_into() {
p.field_enums("Tag", tag, &[FLAGS_DT, proc]);
if d.is_string(endian) {
p.field_string(
"Value",
val,
val.try_into().ok().and_then(|val| dynstr.get(val).ok()),
);
} else {
p.field_hex("Value", val);
if tag == DT_FLAGS {
p.flags(val, 0, FLAGS_DF);
} else if tag == DT_FLAGS_1 {
p.flags(val, 0, FLAGS_DF_1);
}
}
} else {
p.field_hex("Tag", tag);
p.field_hex("Value", val);
}
});
if tag == DT_NULL.into() {
break;
}
}
}

fn print_hash<Elf: FileHeader>(
p: &mut Printer<impl Write>,
endian: Elf::Endian,
Expand Down
53 changes: 53 additions & 0 deletions src/read/elf/dynamic.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
use core::convert::TryInto;
use core::fmt::Debug;

use crate::elf;
Expand All @@ -12,6 +13,58 @@ pub trait Dyn: Debug + Pod {

fn d_tag(&self, endian: Self::Endian) -> Self::Word;
fn d_val(&self, endian: Self::Endian) -> Self::Word;

/// Try to convert the tag to a `u32`.
fn tag32(&self, endian: Self::Endian) -> Option<u32> {
self.d_tag(endian).into().try_into().ok()
}

/// Return true if the value is an offset in the dynamic string table.
fn is_string(&self, endian: Self::Endian) -> bool {
if let Some(tag) = self.tag32(endian) {
match tag {
elf::DT_NEEDED
| elf::DT_SONAME
| elf::DT_RPATH
| elf::DT_RUNPATH
| elf::DT_AUXILIARY
| elf::DT_FILTER => true,
_ => false,
}
} else {
false
}
}

/// Return true if the value is an address.
fn is_address(&self, endian: Self::Endian) -> bool {
if let Some(tag) = self.tag32(endian) {
match tag {
elf::DT_PLTGOT
| elf::DT_HASH
| elf::DT_STRTAB
| elf::DT_SYMTAB
| elf::DT_RELA
| elf::DT_INIT
| elf::DT_FINI
| elf::DT_SYMBOLIC
| elf::DT_REL
| elf::DT_DEBUG
| elf::DT_JMPREL
| elf::DT_FINI_ARRAY
| elf::DT_INIT_ARRAY
| elf::DT_PREINIT_ARRAY
| elf::DT_SYMTAB_SHNDX
| elf::DT_VERDEF
| elf::DT_VERNEED
| elf::DT_VERSYM
| elf::DT_ADDRRNGLO..=elf::DT_ADDRRNGHI => true,
_ => false,
}
} else {
false
}
}
}

impl<Endian: endian::Endian> Dyn for elf::Dyn32<Endian> {
Expand Down
40 changes: 40 additions & 0 deletions src/read/elf/section.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -148,6 +148,25 @@ impl<'data, Elf: FileHeader, R: ReadRef<'data>> SectionTable<'data, Elf, R> {
RelocationSections::parse(endian, self, symbol_section)
}

/// Return the contents of a dynamic section.
///
/// Also returns the linked string table index.
///
/// Returns `Ok(None)` if there is no `SHT_DYNAMIC` section.
/// Returns `Err` for invalid values.
pub fn dynamic(
&self,
endian: Elf::Endian,
data: R,
) -> read::Result<Option<(&'data [Elf::Dyn], SectionIndex)>> {
for section in self.sections {
if let Some(dynamic) = section.dynamic(endian, data)? {
return Ok(Some(dynamic));
}
}
Ok(None)
}

/// Return the header of a SysV hash section.
///
/// Returns `Ok(None)` if there is no SysV GNU hash section.
Expand Down Expand Up @@ -726,6 +745,27 @@ pub trait SectionHeader: Debug + Pod {
Ok(Some((rela, link)))
}

/// Return entries in a dynamic section.
///
/// Also returns the linked string table index.
///
/// Returns `Ok(None)` if the section type is not `SHT_DYNAMIC`.
/// Returns `Err` for invalid values.
fn dynamic<'data, R: ReadRef<'data>>(
&self,
endian: Self::Endian,
data: R,
) -> read::Result<Option<(&'data [<Self::Elf as FileHeader>::Dyn], SectionIndex)>> {
if self.sh_type(endian) != elf::SHT_DYNAMIC {
return Ok(None);
}
let dynamic = self
.data_as_array(endian, data)
.read_error("Invalid ELF dynamic section offset or size")?;
let link = SectionIndex(self.sh_link(endian) as usize);
Ok(Some((dynamic, link)))
}

/// Return a note iterator for the section data.
///
/// Returns `Ok(None)` if the section does not contain notes.
Expand Down