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Add support for GNU RELRO.

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Submitted by:	John Marino <draco marino st>
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2012-01-30 19:52:17 +00:00
parent 1b38b22739
commit 6d7610d75a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=230784
3 changed files with 28 additions and 0 deletions
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12
libexec/rtld-elf/map_object.c
View File

@ -84,6 +84,8 @@ map_object(int fd, const char *path, const struct stat *sb)
Elf_Addr bss_vlimit;
caddr_t bss_addr;
Elf_Word stack_flags;
Elf_Addr relro_page;
size_t relro_size;
hdr = get_elf_header(fd, path);
if (hdr == NULL)
@ -100,6 +102,8 @@ map_object(int fd, const char *path, const struct stat *sb)
nsegs = -1;
phdyn = phinterp = phtls = NULL;
phdr_vaddr = 0;
relro_page = 0;
relro_size = 0;
segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
while (phdr < phlimit) {
@ -134,6 +138,11 @@ map_object(int fd, const char *path, const struct stat *sb)
case PT_GNU_STACK:
stack_flags = phdr->p_flags;
break;
case PT_GNU_RELRO:
relro_page = phdr->p_vaddr;
relro_size = phdr->p_memsz;
break;
}
++phdr;
@ -269,6 +278,9 @@ map_object(int fd, const char *path, const struct stat *sb)
obj->tlsinit = mapbase + phtls->p_vaddr;
}
obj->stack_flags = stack_flags;
obj->relro_page = obj->relocbase + trunc_page(relro_page);
obj->relro_size = round_page(relro_size);
return obj;
}

13
libexec/rtld-elf/rtld.c
View File

@ -1114,6 +1114,11 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
case PT_GNU_STACK:
obj->stack_flags = ph->p_flags;
break;
case PT_GNU_RELRO:
obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
obj->relro_size = round_page(ph->p_memsz);
break;
}
}
if (nsegs < 1) {
@ -2007,6 +2012,14 @@ relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
if (reloc_jmpslots(obj, lockstate) == -1)
return -1;
if (obj->relro_size > 0) {
if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
_rtld_error("%s: Cannot enforce relro protection: %s",
obj->path, strerror(errno));
return -1;
}
}
/*
* Set up the magic number and version in the Obj_Entry. These
* were checked in the crt1.o from the original ElfKit, so we

3
libexec/rtld-elf/rtld.h
View File

@ -168,6 +168,9 @@ typedef struct Struct_Obj_Entry {
size_t tlsoffset; /* Offset of static TLS block for this module */
size_t tlsalign; /* Alignment of static TLS block */
caddr_t relro_page;
size_t relro_size;
/* Items from the dynamic section. */
Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
const Elf_Rel *rel; /* Relocation entries */