sqlelf 0.4

Explore ELF objects through the power of SQL

sqlelf

Explore ELF objects through the power of SQL

A tool that utilizes SQLite's virtual table functionality to allow you to explore Linux ELF objects through SQL.

Traditionally exploring an ELF file was limited to tools such as objdump or readelf. While these tools are full featured in their parsing capability, the output format and ability to ask exploratory questions is limited.

SQL is the lingua franca for asking questions in a declarative manner. Let's enhance our ability to introspect binaries!

---
title: ELF Schema
---
erDiagram
    ELF_HEADERS ||--o{ ELF_SECTIONS : contains
    ELF_HEADERS {
        string path
        int type
        int version
        int machine
        int entry
    }
    ELF_SECTIONS {
        string path
        string name
        int offset
        int size
        int type
        blob content
    }
    ELF_HEADERS ||--o{ ELF_SYMBOLS : contains
    ELF_SECTIONS ||--o{ ELF_SYMBOLS : defined
    ELF_SYMBOLS {
        string path
        string name
        string demangled_name
        bool imported
        bool exported
        int section
        int size
    }
    ELF_HEADERS ||--o{ ELF_DYNAMIC_ENTRIES : defined
    ELF_DYNAMIC_ENTRIES {
        string path
        string tag
        string value
    }
    ELF_SECTIONS ||--o{ ELF_INSTRUCTIONS : contains
    ELF_INSTRUCTIONS {
        string path
        string section
        string mnemonic
        string address
        string operands
    }
    ELF_SECTIONS ||--o{ ELF_STRINGS : contains
    ELF_STRINGS {
        string path
        string section
        string value
    }
    ELF_HEADERS ||--o{ ELF_VERSION_REQUIREMENTS : contains
    ELF_VERSION_REQUIREMENTS {
        string path
        string file
        string name
    }
    ELF_HEADERS ||--o{ ELF_VERSION_DEFINITIONS : contains
    ELF_VERSION_DEFINITIONS {
        string path
        string name
        int flags
    }

Installation

❯ pip install sqlelf
❯ sqlelf /usr/bin/python3 -- \
--sql "select mnemonic, COUNT(*) from elf_instructions GROUP BY mnemonic ORDER BY 2 DESC LIMIT 3"

mov|223497
call|56209
jmp|48213

Usage

❯ sqlelf --help
usage: sqlelf [-h] FILE [FILE ...]

Analyze ELF files with the power of SQL

positional arguments:
  FILE        The ELF file to analyze

options:
  -h, --help            show this help message and exit
  -s SQL, --sql SQL     Potential SQL to execute. Omitting this enters the REPL.
  --recursive, --no-recursive
                        Load all shared libraries needed by each file using ldd

Note: You may provide directories for FILE. Avoid giving too many binaries though since they must all be parsed at startup.

Tour

You simply have to fire up sqlelf and give it a list of binaries or directories and start exploring ELF via SQL.

Simple demo showing a simple SELECT :

❯ sqlelf /usr/bin/ruby --sql "select * from elf_headers"
/usr/bin/ruby|DYNAMIC|x86_64|CURRENT|4400

❯ sqlelf /usr/bin/ruby /bin/ls
SQLite version 3.40.1 (APSW 3.40.0.0)
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .header ON
sqlite> select * from elf_headers;
path|type|machine|version|entry
/usr/bin/ruby|3|62|1|4400
/bin/ls|3|62|1|25040

A more intricate demo showing an INNER JOIN, WHERE and GROUP BY across two tables which each represent different portions of the ELF format.

SQLite version 3.40.1 (APSW 3.40.0.0)
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .header ON
sqlite> SELECT elf_headers.path, COUNT(*) as num_sections
    ..> FROM elf_headers
    ..> INNER JOIN elf_sections ON elf_headers.path = elf_sections.path
    ..> WHERE elf_headers.type = 3
    ..> GROUP BY elf_headers.path;
path|num_sections
/bin/ls|31
/usr/bin/pnmarith|27
/usr/bin/ruby|28

You can provide multiple SQL statements to the CLI. This is useful if you want to invoke many of the special dot commands. You can use .help to see the list of possible commands or refer to the apsw shell documentation.

For instance, to have sqelf emit JSON you can do the following:

❯ sqlelf /usr/bin/ruby --sql ".mode json" --sql "select path,name from elf_sections LIMIT 3;"
{ "path": "\/usr\/bin\/ruby", "name": ""},
{ "path": "\/usr\/bin\/ruby", "name": ".interp"},
{ "path": "\/usr\/bin\/ruby", "name": ".note.gnu.property"},

sqlelf will store the data from the ELF file into in-memory SQLite database. This allows you to run multiple queries against the same file(s) without having to reparse them and is much more efficient than iterating the ELF structures. This comes at the cost of startup time.

You can however dump the sqlite database to a file on disk and then load it back up later. This is useful if you want to run many queries against the same file(s) and don't want to pay the startup cost each time.

❯ sqlelf /nix/store/gjr9ylm023rl9di484g1wxcd1jp84xxv-nix-2.8.1/bin/nix \
    --sql ".dump /tmp/nix.sqlite"
❯ file /tmp/nix-backup.sqlite
/tmp/nix-backup.sqlite: SQLite 3.x database, last written using SQLite version 3043001, writer version 2,
    read version 2, file counter 3, database pages 14069, cookie 0x2, schema 4, UTF-8, version-valid-for 3

Queries

List all symbol resolutions (match import & export)

❯ sqlelf /usr/bin/ruby --sql "SELECT caller.path as 'caller.path',
       callee.path as 'calee.path',
       caller.name,
       caller.demangled_name
FROM ELF_SYMBOLS caller
INNER JOIN ELF_SYMBOLS callee
ON
caller.name = callee.name AND
caller.path != callee.path AND
caller.imported = TRUE AND
callee.exported = TRUE
LIMIT 25;"
┌──────────────────────────────────────────┬──────────────────────────────────────────┬──────────────────────┬──────────────────────┐
│               caller.path                │                calee.path                │         name         │    demangled_name    │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ ruby_run_node        │ ruby_run_node        │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ ruby_init            │ ruby_init            │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ ruby_options         │ ruby_options         │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ ruby_sysinit         │ ruby_sysinit         │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libc.so.6          │ __stack_chk_fail     │ __stack_chk_fail     │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ ruby_init_stack      │ ruby_init_stack      │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libc.so.6          │ setlocale            │ setlocale            │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libc.so.6          │ __libc_start_main    │ __libc_start_main    │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libc.so.6          │ __libc_start_main    │ __libc_start_main    │
│ /usr/bin/ruby                            │ /lib/x86_64-linux-gnu/libc.so.6          │ __cxa_finalize       │ __cxa_finalize       │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ initgroups           │ initgroups           │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libm.so.6          │ log10                │ log10                │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ chmod                │ chmod                │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libgmp.so.10       │ __gmpz_mul           │ __gmpz_mul           │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libm.so.6          │ lgamma_r             │ lgamma_r             │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ symlink              │ symlink              │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ mprotect             │ mprotect             │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ pipe2                │ pipe2                │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ seteuid              │ seteuid              │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ chdir                │ chdir                │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ fileno               │ fileno               │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ dup2                 │ dup2                 │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ pthread_cond_destroy │ pthread_cond_destroy │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libc.so.6          │ pthread_cond_destroy │ pthread_cond_destroy │
│ /lib/x86_64-linux-gnu/libruby-3.1.so.3.1 │ /lib/x86_64-linux-gnu/libm.so.6          │ atan2                │ atan2                │
└──────────────────────────────────────────┴──────────────────────────────────────────┴──────────────────────┴──────────────────────┘

Find symbols that are exported by more than one library

❯ sqlelf ./examples/shadowed-symbols/exe --recursive --sql "
SELECT name, version, count(*) as symbol_count, GROUP_CONCAT(path, ':') as libraries
FROM elf_symbols
WHERE exported = TRUE
GROUP BY name, version
HAVING count(*) >= 2;"
┌──────┬────────┬───────────┬────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ name │ versio │ symbol_co │                                                                       libraries                                                                        │
│      │   n    │    unt    │                                                                                                                                                        │
├──────┼────────┼───────────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ foo  │ NULL   │ 2         │ /usr/local/google/home/fmzakari/code/github.com/fzakaria/sqlelf/examples/shadowed-                                                                     │
│      │        │           │ symbols/x/libx.so:/usr/local/google/home/fmzakari/code/github.com/fzakaria/sqlelf/examples/shadowed-symbols/x/libx2.so                                 │
└──────┴────────┴───────────┴────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

List contained symbols, i.e. a symbol fully within the bounds of another

sqlelf ./examples/nested-symbols/exe --sql "
SELECT outer_symbol.path, 
    outer_symbol.name AS outer_symbol_name, 
    inner_symbol.name AS inner_symbol_name
FROM 
    elf_symbols AS outer_symbol, 
    elf_symbols AS inner_symbol
WHERE
    inner_symbol.section = '.text' AND
    outer_symbol.section = '.text' AND
    inner_symbol.path = outer_symbol.path AND
    inner_symbol.value > outer_symbol.value AND
    (inner_symbol.value + inner_symbol.size) < (outer_symbol.value + outer_symbol.size) AND
    inner_symbol.name != outer_symbol.name LIMIT 5;"
┌──────────────────────────────────┬───────────────────┬───────────────────┐
│               path               │ outer_symbol_name │ inner_symbol_name │
│ ./examples/nested-symbols/nested │ outer_function    │ inner_symbol      │
└──────────────────────────────────┴───────────────────┴───────────────────┘

Determine Python extension version

You will need to edit the SQL below to have the module name. For instance, the below assumes the module name is extension from the pypa/python-manylinux-demo.

❯ sqlelf pypa/python-manylinux-demo/build/lib.linux-x86_64-cpython-311/pymanylinuxdemo/extension.cpython-311-x86_64-linux-gnu.so \
> --sql "SELECT
            CASE name
                WHEN 'initextension' THEN 2
                WHEN 'PyInit_extension' THEN 3
                WHEN '_cffi_pypyinit_extension' THEN 2
                ELSE -1
            END AS python_version
        FROM elf_symbols
        WHERE name IN ('initextension', 'PyInit_extension', '_cffi_pypyinit_extension')
              AND exported = TRUE
              AND type = 'FUNC'
        LIMIT 1
        "
┌────────────────┐
│ python_version │
│ 3              │
└────────────────┘

Determine the NEEDED entries for a program

This may be improved in the future but for now there is a little knowledge of the polymorphic nature of the dynamic entries needed.

❯ sqlelf extension.cpython-311-x86_64-linux-gnu.so \
> --sql "SELECT elf_strings.path, elf_strings.value
FROM elf_dynamic_entries
INNER JOIN elf_strings ON elf_dynamic_entries.value = elf_strings.offset
WHERE elf_dynamic_entries.tag = 'NEEDED'"
┌───────────────────────────────────────────┬───────────────┐
│                   path                    │     value     │
│ extension.cpython-311-x86_64-linux-gnu.so │ libcblas.so.3 │
│ extension.cpython-311-x86_64-linux-gnu.so │ libc.so.6     │
└───────────────────────────────────────────┴───────────────┘

Determine the RPATH/RUNPATH entries for a program

This may be improved in the future but for now there is a little knowledge of the polymorphic nature of the dynamic entries needed.

The below uses a file built with NixOS as they all have RUNPATH set.

❯ sqlelf /nix/store/gjr9ylm023rl9di484g1wxcd1jp84xxv-nix-2.8.1/bin/nix \
 --sql "SELECT elf_strings.path, elf_strings.value
FROM elf_dynamic_entries
INNER JOIN elf_strings ON elf_dynamic_entries.value = elf_strings.offset
WHERE elf_dynamic_entries.tag = 'RUNPATH';"
┌─────────────────────────────────────────────────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                      path                       │                                                                                 value                                                                                 │
├─────────────────────────────────────────────────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ /nix/store/gjr9ylm023rl9di484g1wxcd1jp84xxv-    │ /nix/store/gjr9ylm023rl9di484g1wxcd1jp84xxv-                                                                                                                          │
│ nix-2.8.1/bin/nix                               │ nix-2.8.1/lib:/nix/store/pkxyfwarcq081rybpbnprjmnkiy1cz6g-libsodium-1.0.18/lib:/nix/store/r6mrf9pz4dpax6rcszcmbyrpsk8j6saz-                                           │
│                                                 │ editline-1.17.1/lib:/nix/store/ppm63lvkyfa58sgcnr2ddzh14dy1k9fn-boehm-gc-8.0.6/lib:/nix/store/sgw2i15l01rwxzj62745h30bsjmh7wc1-lowdown-0.11.1-                        │
│                                                 │ lib/lib:/nix/store/bvy2z17rzlvkx2sj7fy99ajm853yv898-glibc-2.34-210/lib:/nix/store/gka59hya7l7qp26s0rydcgq8hj0d7v7k-gcc-11.3.0-lib/lib                                 │
└─────────────────────────────────────────────────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

A recursive query can further be used to split the row into multiple rows.

❯ sqlelf /nix/store/gjr9ylm023rl9di484g1wxcd1jp84xxv-nix-2.8.1/bin/nix \
--sql "WITH split(rpath, str) AS (
    SELECT '', elf_strings.value||':' as rpath
    FROM elf_dynamic_entries
    INNER JOIN elf_strings ON elf_dynamic_entries.value = elf_strings.offset
    WHERE elf_dynamic_entries.tag = 'RUNPATH'
    UNION ALL SELECT
    substr(str, 0, instr(str, ':')),
    substr(str, instr(str, ':')+1)
    FROM split WHERE str!=''
) SELECT rpath FROM split WHERE rpath!='';"
WARNING:root:SQLITE_LOG: automatic index on elf_strings(offset) (284) SQLITE_WARNING SQLITE_WARNING_AUTOINDEX
┌────────────────────────────────────────────────────────────────────┐
│                               rpath                                │
│ /nix/store/gjr9ylm023rl9di484g1wxcd1jp84xxv-nix-2.8.1/lib          │
│ /nix/store/pkxyfwarcq081rybpbnprjmnkiy1cz6g-libsodium-1.0.18/lib   │
│ /nix/store/r6mrf9pz4dpax6rcszcmbyrpsk8j6saz-editline-1.17.1/lib    │
│ /nix/store/ppm63lvkyfa58sgcnr2ddzh14dy1k9fn-boehm-gc-8.0.6/lib     │
│ /nix/store/sgw2i15l01rwxzj62745h30bsjmh7wc1-lowdown-0.11.1-lib/lib │
│ /nix/store/bvy2z17rzlvkx2sj7fy99ajm853yv898-glibc-2.34-210/lib     │
│ /nix/store/gka59hya7l7qp26s0rydcgq8hj0d7v7k-gcc-11.3.0-lib/lib     │
└────────────────────────────────────────────────────────────────────┘

Development

You may want to install the package in editable mode as well to make development easier

> python3 -m venv venv
> source venv/bin/activate
> pip install --editable ".[dev]"

A helping Makefile is provided to run all the linters and formatters.

> make lint
> make fmt