On 5/11/20 9:33 AM, Eric W. Biederman wrote: > What I do see is that interp_data is just a parameter that is smuggled > into the call of search binary handler. And the next binary handler > needs to be binfmt_elf for it to make much sense, as only binfmt_elf > (and binfmt_elf_fdpic) deals with BINPRM_FLAGS_EXECFD. The binfmt_elf_fdpic driver is separate from binfmt_elf for the same reason ext2/ext3/ext4 used to have 3 drivers: fdpic is really just binfmt_elf with the 4 main sections (text, data, bss, rodata) able to move independently of each other (each tracked with its own base pointer). It's kind of -fPIE on steroids, and various security people have sniffed at it over the years to give ASLR more degrees of freedom on with-MMU systems. Many moons ago Rich Felker proposed teaching the fdpic loader how to load normal ELF binaries so there's just the one loader (there's a flag in the ELF header to say whether the sections are independent or not). Rob
