Embedding Binary Objects in C
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Embedding Binary Objects in C
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Re: Embedding Binary Objects in C
#2Is it possible to automate this with cmake?
Re: Embedding Binary Objects in C
#3Or, as any CTFer worth their salt will tell you,
__asm__(“.incbin file”);Re: Embedding Binary Objects in C
#4Where did they define the symbols `_binary_quine_c_start` and `_binary_quine_c_end`? I would expect that the symbol names would need to be passed to the command that produced the object file from the binary file:
ld -r -b binary quine.c -o myself.o -m elf_amd64Re: Embedding Binary Objects in C
#5There's also gnu's objcopy.
This post covers a lot of different approaches, and has lots of tips: https://www.devever.net/~hl/incbin
Re: Embedding Binary Objects in C
#6Where did they define the symbols `_binary_quine_c_start` and `_binary_quine_c_end`? I would expect that the symbol names would need to be passed to the command that produced the object file from the binary file: ld -r -b binary quine.c -o myself.o -m elf_amd64
> I would expect that the symbol names would need to be passed to the command that produced the object file from the binary file:
It's the other way around. The command produces these symbols basing on the file name:
$ readelf --symbols myself.o
Symbol table '.symtab' contains 5 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 SECTION LOCAL DEFAULT 1
2: 0000000000000000 0 NOTYPE GLOBAL DEFAULT 1 _binary_quine_c_start
3: 0000000000000113 0 NOTYPE GLOBAL DEFAULT ABS _binary_quine_c_size
4: 0000000000000113 0 NOTYPE GLOBAL DEFAULT 1 _binary_quine_c_endRe: Embedding Binary Objects in C
#7There's also gnu's objcopy. This post covers a lot of different approaches, and has lots of tips: https://www.devever.net/~hl/incbin
thanks
Re: Embedding Binary Objects in C
#8Is it possible to automate this with cmake?
I used to have this automated as part of a makefile, so I'd say yes.
Re: Embedding Binary Objects in C
#9Where did they define the symbols `_binary_quine_c_start` and `_binary_quine_c_end`? I would expect that the symbol names would need to be passed to the command that produced the object file from the binary file: ld -r -b binary quine.c -o myself.o -m elf_amd64
Those are standardized named generated by ld, derived from the file name (in this case "quine", which is treated by the author both as C source and a binary data file).
I bet there's a CLI switch to change the defaults.
Re: Embedding Binary Objects in C
#10Related Twitter discussion: https://twitter.com/taviso/status/1250518818197245953