The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=1a28d9343c5b70d5404133d599e7e01c3d021d0f
commit 1a28d9343c5b70d5404133d599e7e01c3d021d0f Author: Konstantin Belousov <[email protected]> AuthorDate: 2021-11-11 18:07:44 +0000 Commit: Konstantin Belousov <[email protected]> CommitDate: 2022-01-02 16:43:01 +0000 rtld: load preloaded vdso (cherry picked from commit c210ef1347929cb3a0f46cdfdb3d4ad738e3af74) --- libexec/rtld-elf/rtld.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c index af29d3ead390..5819bf18e4b5 100644 --- a/libexec/rtld-elf/rtld.c +++ b/libexec/rtld-elf/rtld.c @@ -125,6 +125,7 @@ static void load_filtees(Obj_Entry *, int flags, RtldLockState *); static void unload_filtees(Obj_Entry *, RtldLockState *); static int load_needed_objects(Obj_Entry *, int); static int load_preload_objects(const char *, bool); +static int load_kpreload(const void *addr); static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int); static void map_stacks_exec(RtldLockState *); static int obj_disable_relro(Obj_Entry *); @@ -828,6 +829,13 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) if (!libmap_disable) libmap_disable = (bool)lm_init(libmap_override); + if (aux_info[AT_KPRELOAD] != NULL && + aux_info[AT_KPRELOAD]->a_un.a_ptr != NULL) { + dbg("loading kernel vdso"); + if (load_kpreload(aux_info[AT_KPRELOAD]->a_un.a_ptr) == -1) + rtld_die(); + } + dbg("loading LD_PRELOAD_FDS libraries"); if (load_preload_objects(ld_preload_fds, true) == -1) rtld_die(); @@ -2842,6 +2850,77 @@ errp: return (NULL); } +static int +load_kpreload(const void *addr) +{ + Obj_Entry *obj; + const Elf_Ehdr *ehdr; + const Elf_Phdr *phdr, *phlimit, *phdyn, *seg0, *segn; + static const char kname[] = "[vdso]"; + + ehdr = addr; + if (!check_elf_headers(ehdr, "kpreload")) + return (-1); + obj = obj_new(); + phdr = (const Elf_Phdr *)((const char *)addr + ehdr->e_phoff); + obj->phdr = phdr; + obj->phsize = ehdr->e_phnum * sizeof(*phdr); + phlimit = phdr + ehdr->e_phnum; + seg0 = segn = NULL; + + for (; phdr < phlimit; phdr++) { + switch (phdr->p_type) { + case PT_DYNAMIC: + phdyn = phdr; + break; + case PT_GNU_STACK: + /* Absense of PT_GNU_STACK implies stack_flags == 0. */ + obj->stack_flags = phdr->p_flags; + break; + case PT_LOAD: + if (seg0 == NULL || seg0->p_vaddr > phdr->p_vaddr) + seg0 = phdr; + if (segn == NULL || segn->p_vaddr + segn->p_memsz < + phdr->p_vaddr + phdr->p_memsz) + segn = phdr; + break; + } + } + + obj->mapbase = __DECONST(caddr_t, addr); + obj->mapsize = segn->p_vaddr + segn->p_memsz - (Elf_Addr)addr; + obj->vaddrbase = 0; + obj->relocbase = obj->mapbase; + + object_add_name(obj, kname); + obj->path = xstrdup(kname); + obj->dynamic = (const Elf_Dyn *)(obj->relocbase + phdyn->p_vaddr); + + if (!digest_dynamic(obj, 0)) { + obj_free(obj); + return (-1); + } + + /* + * We assume that kernel-preloaded object does not need + * relocation. It is currently written into read-only page, + * handling relocations would mean we need to allocate at + * least one additional page per AS. + */ + dbg("%s mapbase %p phdrs %p PT_LOAD phdr %p vaddr %p dynamic %p", + obj->path, obj->mapbase, obj->phdr, seg0, + obj->relocbase + seg0->p_vaddr, obj->dynamic); + + TAILQ_INSERT_TAIL(&obj_list, obj, next); + obj_count++; + obj_loads++; + linkmap_add(obj); /* for GDB & dlinfo() */ + max_stack_flags |= obj->stack_flags; + + LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, 0, 0, obj->path); + return (0); +} + Obj_Entry * obj_from_addr(const void *addr) {
