Date: Sat, 24 Jan 2009 22:35:04 GMT From: Robert Watson <rwatson@FreeBSD.org> To: Perforce Change Reviews <perforce@freebsd.org> Subject: PERFORCE change 156625 for review Message-ID: <200901242235.n0OMZ4nv087984@repoman.freebsd.org>
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http://perforce.freebsd.org/chv.cgi?CH=156625 Change 156625 by rwatson@rwatson_freebsd_capabilities on 2009/01/24 22:34:21 The capability-mode rtld-elf behaves a bit differently: we pass the binary to execute as file descriptor 3, which rtld will map and then execute. Do this by mocking up an AT_EXECFD ELF auxiliary argument -- let's see if this long-unused code in rtld works. Affected files ... .. //depot/projects/trustedbsd/capabilities/src/libexec/rtld-elf/rtld.c#5 edit Differences ... ==== //depot/projects/trustedbsd/capabilities/src/libexec/rtld-elf/rtld.c#5 (text+ko) ==== @@ -304,6 +304,10 @@ func_ptr_type _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) { +#ifdef IN_RTLD_CAP + struct stat sb; + Elf_Auxinfo aux_execfd; +#endif Elf_Auxinfo *aux_info[AT_COUNT]; int i; int argc; @@ -342,10 +346,32 @@ aux_info[auxp->a_type] = auxp; } +#ifdef IN_RTLD_CAP + /* + * In capability mode, the kernel has executed ld-elf-cap.so directly, + * and the parent has passed the executable it wants us to run as a file + * descriptor. The kernel doesn't know this, so rewrite our auxilary + * arguments so the remainder of rtld thinks the kernel passed the file + * descriptor using AT_EXECFD. + */ + if (aux_info[AT_EXECFD] == NULL) { + bzero(&aux_execfd, sizeof(aux_execfd)); + aux_execfd.a_type = AT_EXECFD; + aux_execfd.a_un.a_val = 3; + aux_info[AT_EXECFD] = &aux_execfd; + if (fstat(3, &sb) < 0) { + __progname = "ld-elf-cap.so"; + _rtld_error("executable file descriptor unusable"); + die(); + } + } +#endif + /* Initialize and relocate ourselves. */ assert(aux_info[AT_BASE] != NULL); init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); + /* XXXRW: Need to do something about program names in capability mode. */ __progname = obj_rtld.path; argv0 = argv[0] != NULL ? argv[0] : "(null)"; environ = env; @@ -527,23 +553,6 @@ return (func_ptr_type) obj_main->entry; } -#ifdef IN_RTLD_CAP -/* - * If we are ld-elf-cap.so, then we are directly executed using fexecve(2) - * and will need to behave a bit differently: - * - * (1) The ELF auxilary arguments are for our own binary. - * (2) The main binary we want to execute will be passed as a file descriptor - * so we'll mock up AT_COUNT. - */ -int -_rtld_cap_start(int argc, char *argv[]) -{ - - _exit(0); -} -#endif - Elf_Addr _rtld_bind(Obj_Entry *obj, Elf_Size reloff) {
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