diff --git a/libexec/rtld-elf/map_object.c b/libexec/rtld-elf/map_object.c index f4f6f4221816..30af4cefddbe 100644 --- a/libexec/rtld-elf/map_object.c +++ b/libexec/rtld-elf/map_object.c @@ -39,7 +39,6 @@ #include "rtld.h" static Elf_Ehdr *get_elf_header(int, const char *, const struct stat *); -static int convert_prot(int); /* Elf flags -> mmap protection */ static int convert_flags(int); /* Elf flags -> mmap flags */ /* @@ -445,7 +444,7 @@ obj_new(void) * Given a set of ELF protection flags, return the corresponding protection * flags for MMAP. */ -static int +int convert_prot(int elfflags) { int prot = 0; diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c index 912358c0c1d1..6a405c30f508 100644 --- a/libexec/rtld-elf/rtld.c +++ b/libexec/rtld-elf/rtld.c @@ -2626,6 +2626,40 @@ relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj, return (error); } +/* + * Prepare for, or clean after, relocating an object marked with + * DT_TEXTREL or DF_TEXTREL. Before relocating, all read-only + * segments are remapped read-write. After relocations are done, the + * segment's permissions are returned back to the modes specified in + * the phdrs. If any relocation happened, or always for wired + * program, COW is triggered. + */ +static int +reloc_textrel_prot(Obj_Entry *obj, bool before) +{ + const Elf_Phdr *ph; + void *base; + size_t l, sz; + int prot; + + for (l = obj->phsize / sizeof(*ph), ph = obj->phdr; l > 0; + l--, ph++) { + if (ph->p_type != PT_LOAD || (ph->p_flags & PF_W) != 0) + continue; + base = obj->relocbase + trunc_page(ph->p_vaddr); + sz = round_page(ph->p_vaddr + ph->p_filesz) - + trunc_page(ph->p_vaddr); + prot = convert_prot(ph->p_flags) | (before ? PROT_WRITE : 0); + if (mprotect(base, sz, prot) == -1) { + _rtld_error("%s: Cannot write-%sable text segment: %s", + obj->path, before ? "en" : "dis", + rtld_strerror(errno)); + return (-1); + } + } + return (0); +} + /* * Relocate single object. * Returns 0 on success, or -1 on failure. @@ -2648,28 +2682,17 @@ relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj, return (-1); } - if (obj->textrel) { - /* There are relocations to the write-protected text segment. */ - if (mprotect(obj->mapbase, obj->textsize, - PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { - _rtld_error("%s: Cannot write-enable text segment: %s", - obj->path, rtld_strerror(errno)); - return (-1); - } - } + /* There are relocations to the write-protected text segment. */ + if (obj->textrel && reloc_textrel_prot(obj, true) != 0) + return (-1); /* Process the non-PLT non-IFUNC relocations. */ if (reloc_non_plt(obj, rtldobj, flags, lockstate)) return (-1); - if (obj->textrel) { /* Re-protected the text segment. */ - if (mprotect(obj->mapbase, obj->textsize, - PROT_READ|PROT_EXEC) == -1) { - _rtld_error("%s: Cannot write-protect text segment: %s", - obj->path, rtld_strerror(errno)); - return (-1); - } - } + /* Re-protected the text segment. */ + if (obj->textrel && reloc_textrel_prot(obj, false) != 0) + return (-1); /* Set the special PLT or GOT entries. */ init_pltgot(obj); diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h index 5fbfb271a3bf..8b7024b841ad 100644 --- a/libexec/rtld-elf/rtld.h +++ b/libexec/rtld-elf/rtld.h @@ -385,6 +385,7 @@ void *allocate_module_tls(int index); bool allocate_tls_offset(Obj_Entry *obj); void free_tls_offset(Obj_Entry *obj); const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long); +int convert_prot(int elfflags); /* * MD function declarations.