Elf file format header

I like objdump. President James K. Polk President James K. Polk Amen to that. Oh, and IDA Pro ain't half-bad either for looking at elf files ; — joveha. PhiS PhiS 4, 21 21 silver badges 34 34 bronze badges. Guru Kas Guru Kas 21 1 1 bronze badge. Jichao Jichao Piotr Zierhoffer Piotr Zierhoffer 5, 1 1 gold badge 37 37 silver badges 57 57 bronze badges.

The Overflow Blog. Podcast Helping communities build their own LTE networks. Podcast Making Agile work for data science. Featured on Meta. As for the touch command, there are 27 section headers, and Listing 5 shows the first four of them plus the last one, only. Each line covers the section size, the section type as well as its address and memory offset. The first candidate we will have a look at is the file utility. The second candidate is readelf.

It displays detailed information about an ELF file. The list of switches is comparably long, and covers all the aspects of the ELF format. Using the switch -n short for —notes Listing 7 shows the note sections, only, that exist in the file touch — the ABI version tag, and the build ID bitstring.

As of , there has not been a new release or update since Number three is the package named elfutils [6] that is purely available for Linux. Last but not least we will mention objdump. This tool is similar to readelf but focuses on object files.

It provides a similar range of information about ELF files and other object formats. This set of utilities provides a number of tools that help to validate ELF files. As an example, dumpelf analyzes the ELF file, and returns a C header file containing the details — see Figure 2. Thanks to a combination of clever design and excellent documentation the ELF format works very well, and is still in use after 20 years. The utilities shown above allow you an insight view into an ELF file, and let you figure out what a program is doing.

These are the first steps for analyzing software — happy hacking! The writer would like to thank Axel Beckert for his support regarding the preparation of this article. For an executable program, these are the text section for the code, the data section for global variables and the rodata section that usually contains constant strings.

The ELF file contains headers that describe how these sections should be stored in memory. Note that depending on whether your file is a linkable or an executable file, the headers in the ELF file won't be the same: process. The 'flags' will tell you what's actually available in the ELF file. Here, we have symbol tables and relocation: all that we need to link the file against another, but virtually no information about how to load the file in memory even if that could be guessed.

We don't have the program entry point, for instance, and we have a sections table rather than a program header. The program that should be used to 'execute' the binary. Now we're requested to read c bytes, starting at file's start? They'll be to appear starting at virtual address 0x for the program to work properly. More bits to load, likely to be. Notice that the 'filesize' and 'memsize' differ, which means the.

The dynamic sections are used to store information used in the dynamic linking process, such as required libraries and relocation entries. That means, however, that a part of the code is mapped twice, but with different permissions. I suggest you do give them different physical pages too if you don't want to end up with modifiable code.

The format of this header is described in the ELF Specification. The most relevant sections for this purpose are 1.