rtld: Support multiple PT_GNU_RELRO program headers
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Authored by jhb on Dec 3 2024, 6:53 PM.

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Reviewers

kib
jrtc27

Commits

rGfda0403eb083: rtld: Support multiple PT_GNU_RELRO program headers

Summary

Iterate over all the program headers in obj_remap_relro and remove the
relro fields from Obj_Entry.

Skip the call to obj_enforce_relro() in relocate_object() for the rtld
object as well as the main program object. obj_enforce_relro() is
called later when it safe to reference globals such as page_size.

Obtained from: CheriBSD

Diff Detail

Repository

rG FreeBSD src repository

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Unit

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Build Status

Buildable 60962
Build 57846: arc lint + arc unit

Event Timeline

jhb created this revision.Dec 3 2024, 6:53 PM

Herald added subscribers: bdragon, imp. · View Herald TranscriptDec 3 2024, 6:53 PM

jhb requested review of this revision.Dec 3 2024, 6:53 PM

Harbormaster completed remote builds in B60933: Diff 147410.Dec 3 2024, 6:53 PM

jhb added inline comments.Dec 3 2024, 6:56 PM

libexec/rtld-elf/rtld.c
5911	I think I picked the wrong one of the 3 copies of this and that this should be: relro_size = rtld_trunc_page(ph->p_vaddr + ph->p_memsz) - rtld_trunc_page(ph->p_vaddr);

kib added inline comments.Dec 3 2024, 8:09 PM

libexec/rtld-elf/rtld.c
5911	Not relro_size = rtld_round_page(ph->p_vaddr + ph->p_memsz) - rtld_trunc_page(ph->p_vaddr); ?

jhb added inline comments.Dec 3 2024, 9:16 PM

libexec/rtld-elf/map_object.c
327	This should have used `rtld_round_page`
libexec/rtld-elf/rtld.c
1677	This should have used `rtld_round_page`
2375	This is missing adding the sub-page offset of `ph->p_vaddr` to to the input to `rtld_round_page`
5911	Geeze, yeah, I guess all 3 versions were broken in some fashion then.