Efficiently adding a new section in an ELF file

Question

I want to add a new section to an ELF file (say E) which stores the integrity hash of .text section. Assume I chunk the .text section into T1,T2..Tn and get the hash H1,H2..Hn and add all hashes to the E in a new .my_hash section.

One naive way to do this would be to

• Scan file E and compute/store the hashes in a separate binary file B
• Convert B to B.o file
• Do objcopy --rename_section to rename .data section to .my_hash section
• Finally merge E.o (which assume I also have before generating E) and B.o

Any better way to do this?

Answer 1

Use objcopy --add-section. You may want --set-section-flags as well.