Author: jonathan Date: Wed May 17 22:51:28 2017 New Revision: 318431 URL: https://svnweb.freebsd.org/changeset/base/318431
Log: Allow rtld direct-exec to take a file descriptor. When executing rtld directly, allow a file descriptor to be explicitly specified rather than opened from the given path. This, together with the LD_LIBRARY_PATH_FDS environment variable, allows dynamically-linked applications to be executed from within capability mode. Also add some rudimentary argument parsing (without pulling in getopt or the like) to accept this file descriptor, a help (-h) option and a basic usage string. Reviewed by: kib Sponsored by: NSERC, RDC Differential Revision: https://reviews.freebsd.org/D10751 Modified: head/libexec/rtld-elf/rtld.c Modified: head/libexec/rtld-elf/rtld.c ============================================================================== --- head/libexec/rtld-elf/rtld.c Wed May 17 22:29:25 2017 (r318430) +++ head/libexec/rtld-elf/rtld.c Wed May 17 22:51:28 2017 (r318431) @@ -115,8 +115,10 @@ static void objlist_push_head(Objlist *, static void objlist_push_tail(Objlist *, Obj_Entry *); static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *); static void objlist_remove(Objlist *, Obj_Entry *); +static int parse_args(char* argv[], int argc, bool *use_pathp, int *fdp); static int parse_integer(const char *); static void *path_enumerate(const char *, path_enum_proc, void *); +static void print_usage(const char *argv0); static void release_object(Obj_Entry *); static int relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj, int flags, RtldLockState *lockstate); @@ -350,9 +352,9 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_ char **argv, *argv0, **env, **envp, *kexecpath, *library_path_rpath; caddr_t imgentry; char buf[MAXPATHLEN]; - int argc, fd, i, mib[2], phnum; + int argc, fd, i, mib[2], phnum, rtld_argc; size_t len; - bool dir_enable; + bool dir_enable, explicit_fd, search_in_path; /* * On entry, the dynamic linker itself has not been relocated yet. @@ -428,15 +430,19 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_ } dbg("opening main program in direct exec mode"); if (argc >= 2) { - argv0 = argv[1]; - fd = open(argv0, O_RDONLY | O_CLOEXEC | O_VERIFY); + rtld_argc = parse_args(argv, argc, &search_in_path, &fd); + argv0 = argv[rtld_argc]; + explicit_fd = (fd != -1); + if (!explicit_fd) + fd = open(argv0, O_RDONLY | O_CLOEXEC | O_VERIFY); if (fd == -1) { rtld_printf("Opening %s: %s\n", argv0, rtld_strerror(errno)); rtld_die(); } if (fstat(fd, &st) == -1) { - rtld_printf("Stat %s: %s\n", argv0, + _rtld_error("failed to fstat FD %d (%s): %s", fd, + explicit_fd ? "user-provided descriptor" : argv0, rtld_strerror(errno)); rtld_die(); } @@ -469,26 +475,23 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_ /* * For direct exec mode, argv[0] is the interpreter - * name, we must remove it and shift arguments left by - * 1 before invoking binary main. Since stack layout + * name, we must remove it and shift arguments left + * before invoking binary main. Since stack layout * places environment pointers and aux vectors right * after the terminating NULL, we must shift * environment and aux as well. - * XXX Shift will be > 1 when options are implemented. */ + main_argc = argc - rtld_argc; + for (i = 0; i <= main_argc; i++) + argv[i] = argv[i + rtld_argc]; + *argcp -= rtld_argc; + environ = env = envp = argv + main_argc + 1; do { - *argv = *(argv + 1); - argv++; - } while (*argv != NULL); - *argcp -= 1; - main_argc = argc - 1; - environ = env = envp = argv; - do { - *envp = *(envp + 1); + *envp = *(envp + rtld_argc); envp++; } while (*envp != NULL); aux = auxp = (Elf_Auxinfo *)envp; - auxpf = (Elf_Auxinfo *)(envp + 1); + auxpf = (Elf_Auxinfo *)(envp + rtld_argc); for (;; auxp++, auxpf++) { *auxp = *auxpf; if (auxp->a_type == AT_NULL) @@ -5274,6 +5277,81 @@ symlook_init_from_req(SymLook *dst, cons /* + * Parse a set of command-line arguments. + */ +static int +parse_args(char* argv[], int argc, bool *use_pathp, int *fdp) +{ + const char *arg; + int fd, i, j, arglen; + char opt; + + dbg("Parsing command-line arguments"); + *use_pathp = false; + *fdp = -1; + + for (i = 1; i < argc; i++ ) { + arg = argv[i]; + dbg("argv[%d]: '%s'", i, arg); + + /* + * rtld arguments end with an explicit "--" or with the first + * non-prefixed argument. + */ + if (strcmp(arg, "--") == 0) { + i++; + break; + } + if (arg[0] != '-') + break; + + /* + * All other arguments are single-character options that can + * be combined, so we need to search through `arg` for them. + */ + arglen = strlen(arg); + for (j = 1; j < arglen; j++) { + opt = arg[j]; + if (opt == 'h') { + print_usage(argv[0]); + rtld_die(); + } else if (opt == 'f') { + /* + * -f XX can be used to specify a descriptor for the + * binary named at the command line (i.e., the later + * argument will specify the process name but the + * descriptor is what will actually be executed) + */ + if (j != arglen - 1) { + /* -f must be the last option in, e.g., -abcf */ + _rtld_error("invalid options: %s", arg); + rtld_die(); + } + i++; + fd = parse_integer(argv[i]); + if (fd == -1) { + _rtld_error("invalid file descriptor: '%s'", + argv[i]); + rtld_die(); + } + *fdp = fd; + break; + /* TODO: + } else if (opt == 'p') { + *use_pathp = true; + */ + } else { + rtld_printf("invalid argument: '%s'\n", arg); + print_usage(argv[0]); + rtld_die(); + } + } + } + + return (i); +} + +/* * Parse a file descriptor number without pulling in more of libc (e.g. atoi). */ static int @@ -5300,6 +5378,20 @@ parse_integer(const char *str) return (n); } +void print_usage(const char *argv0) +{ + + rtld_printf("Usage: %s [-h] [-f <FD>] [--] <binary> [<args>]\n" + "\n" + "Options:\n" + " -h Display this help message\n" + /* TODO: " -p Search in PATH for named binary\n" */ + " -f <FD> Execute <FD> instead of searching for <binary>\n" + " -- End of RTLD options\n" + " <binary> Name of process to execute\n" + " <args> Arguments to the executed process\n", argv0); +} + /* * Overrides for libc_pic-provided functions. */ _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
