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Allow PT_NOTES segments to be located anywhere in the executable

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image.

The dynamic linker still requires that program headers of the
executable or dso are mapped by a PT_LOAD segment.

Reviewed by:	emaste, jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D3871
This commit is contained in:
Konstantin Belousov 2015-10-14 18:29:21 +00:00
parent 6c775eb64e
commit bd56d410c4
1 changed files with 21 additions and 3 deletions
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24
libexec/rtld-elf/map_object.c
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@ -88,6 +88,8 @@ map_object(int fd, const char *path, const struct stat *sb)
size_t relro_size;
Elf_Addr note_start;
Elf_Addr note_end;
char *note_map;
size_t note_map_len;
hdr = get_elf_header(fd, path);
if (hdr == NULL)
@ -108,6 +110,7 @@ map_object(int fd, const char *path, const struct stat *sb)
relro_size = 0;
note_start = 0;
note_end = 0;
note_map = NULL;
segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
while (phdr < phlimit) {
@ -150,9 +153,20 @@ map_object(int fd, const char *path, const struct stat *sb)
case PT_NOTE:
if (phdr->p_offset > PAGE_SIZE ||
phdr->p_offset + phdr->p_filesz > PAGE_SIZE)
break;
note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
phdr->p_offset + phdr->p_filesz > PAGE_SIZE) {
note_map_len = round_page(phdr->p_offset +
phdr->p_filesz) - trunc_page(phdr->p_offset);
note_map = mmap(NULL, note_map_len, PROT_READ,
MAP_PRIVATE, fd, trunc_page(phdr->p_offset));
if (note_map == MAP_FAILED) {
_rtld_error("%s: error mapping PT_NOTE (%d)", path, errno);
goto error;
}
note_start = (Elf_Addr)(note_map + phdr->p_offset -
trunc_page(phdr->p_offset));
} else {
note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
}
note_end = note_start + phdr->p_filesz;
break;
}
@ -295,12 +309,16 @@ map_object(int fd, const char *path, const struct stat *sb)
obj->relro_size = round_page(relro_size);
if (note_start < note_end)
digest_notes(obj, note_start, note_end);
if (note_map != NULL)
munmap(note_map, note_map_len);
munmap(hdr, PAGE_SIZE);
return (obj);
error1:
munmap(mapbase, mapsize);
error:
if (note_map != NULL && note_map != MAP_FAILED)
munmap(note_map, note_map_len);
munmap(hdr, PAGE_SIZE);
return (NULL);
}