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Support BTI in rtld
Read the elf note to decide when to set the guard page on arm64. Reviewed by: kib Sponsored by: Arm Ltd Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D39452
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@ -29,6 +29,8 @@
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#include <sys/types.h>
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#include <machine/sysarch.h>
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#include <stdlib.h>
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#include "debug.h"
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@ -52,6 +54,51 @@ void *_rtld_tlsdesc_dynamic(void *);
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void _exit(int);
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bool
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arch_digest_note(struct Struct_Obj_Entry *obj __unused, const Elf_Note *note)
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{
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const char *note_name;
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const uint32_t *note_data;
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note_name = (const char *)(note + 1);
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/* Only handle GNU notes */
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if (note->n_namesz != sizeof(ELF_NOTE_GNU) ||
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strncmp(note_name, ELF_NOTE_GNU, sizeof(ELF_NOTE_GNU)) != 0)
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return (false);
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/* Only handle GNU property notes */
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if (note->n_type != NT_GNU_PROPERTY_TYPE_0)
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return (false);
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/*
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* note_data[0] - Type
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* note_data[1] - Length
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* note_data[2] - Data
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* note_data[3] - Padding?
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*/
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note_data = (const uint32_t *)(note_name + note->n_namesz);
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/* Only handle AArch64 feature notes */
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if (note_data[0] != GNU_PROPERTY_AARCH64_FEATURE_1_AND)
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return (false);
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/* We expect at least 4 bytes of data */
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if (note_data[1] < 4)
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return (false);
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/* TODO: Only guard if HWCAP2_BTI is set */
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if ((note_data[2] & GNU_PROPERTY_AARCH64_FEATURE_1_BTI) != 0) {
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struct arm64_guard_page_args guard;
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guard.addr = (uintptr_t)obj->mapbase;
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guard.len = obj->mapsize;
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sysarch(ARM64_GUARD_PAGE, &guard);
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}
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return (true);
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}
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void
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init_pltgot(Obj_Entry *obj)
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{
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@ -45,6 +45,8 @@ struct Struct_Obj_Entry;
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(const Elf_Dyn *)_dynamic_addr; \
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})
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bool arch_digest_note(struct Struct_Obj_Entry *obj, const Elf_Note *note);
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *defobj, const struct Struct_Obj_Entry *obj,
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const Elf_Rel *rel);
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@ -39,6 +39,9 @@ struct Struct_Obj_Entry;
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Elf_Dyn *rtld_dynamic_addr(void);
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#define rtld_dynamic(obj) rtld_dynamic_addr()
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/* No architecture specific notes */
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#define arch_digest_note(obj, note) false
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *obj, const struct Struct_Obj_Entry *refobj,
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const Elf_Rel *rel);
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@ -39,6 +39,9 @@ struct Struct_Obj_Entry;
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/* Return the address of the .dynamic section in the dynamic linker. */
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#define rtld_dynamic(obj) (&_DYNAMIC)
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/* No architecture specific notes */
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#define arch_digest_note(obj, note) false
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *defobj, const struct Struct_Obj_Entry *obj,
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const Elf_Rel *rel);
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@ -39,6 +39,9 @@ struct Struct_Obj_Entry;
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#define rtld_dynamic(obj) \
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((const Elf_Dyn *)((obj)->relocbase + (Elf_Addr)&_DYNAMIC))
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/* No architecture specific notes */
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#define arch_digest_note(obj, note) false
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *obj, const struct Struct_Obj_Entry *refobj,
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const Elf_Rel *rel);
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@ -38,6 +38,9 @@ struct Struct_Obj_Entry;
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/* Return the address of the .dynamic section in the dynamic linker. */
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#define rtld_dynamic(obj) (&_DYNAMIC)
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/* No architecture specific notes */
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#define arch_digest_note(obj, note) false
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *defobj, const struct Struct_Obj_Entry *obj,
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const Elf_Rel *rel);
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@ -38,6 +38,9 @@ struct Struct_Obj_Entry;
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/* Return the address of the .dynamic section in the dynamic linker. */
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#define rtld_dynamic(obj) (&_DYNAMIC)
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/* No architecture specific notes */
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#define arch_digest_note(obj, note) false
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *defobj, const struct Struct_Obj_Entry *obj,
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const Elf_Rel *rel);
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@ -52,6 +52,9 @@ uint64_t set_gp(struct Struct_Obj_Entry *obj);
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(const Elf_Dyn *)_dynamic_addr; \
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})
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/* No architecture specific notes */
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#define arch_digest_note(obj, note) false
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Elf_Addr reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
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const struct Struct_Obj_Entry *defobj, const struct Struct_Obj_Entry *obj,
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const Elf_Rel *rel);
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@ -1729,6 +1729,9 @@ digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
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note = (const Elf_Note *)((const char *)(note + 1) +
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roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
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roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
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if (arch_digest_note(obj, note))
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continue;
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if (note->n_namesz != sizeof(NOTE_FREEBSD_VENDOR) ||
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note->n_descsz != sizeof(int32_t))
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continue;
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