From owner-dev-commits-src-all@freebsd.org Tue Aug 17 12:06:50 2021 Return-Path: Delivered-To: dev-commits-src-all@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id A4AA266322C; Tue, 17 Aug 2021 12:06:50 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4GpqWt3ZXzz4hf2; Tue, 17 Aug 2021 12:06:50 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 5FA7B1D07B; Tue, 17 Aug 2021 12:06:50 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 17HC6o6q038611; Tue, 17 Aug 2021 12:06:50 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 17HC6o6i038610; Tue, 17 Aug 2021 12:06:50 GMT (envelope-from git) Date: Tue, 17 Aug 2021 12:06:50 GMT Message-Id: <202108171206.17HC6o6i038610@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Konstantin Belousov Subject: git: bfd4c875a105 - main - rtld: avoid use of of getenv(3) for evaluating rtld env vars (LD_XXX) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: kib X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: bfd4c875a10560aaa2f41e82114df79fde008fdb Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-all@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for all branches of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Aug 2021 12:06:50 -0000 The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=bfd4c875a10560aaa2f41e82114df79fde008fdb commit bfd4c875a10560aaa2f41e82114df79fde008fdb Author: Konstantin Belousov AuthorDate: 2021-08-16 12:59:05 +0000 Commit: Konstantin Belousov CommitDate: 2021-08-17 12:05:47 +0000 rtld: avoid use of of getenv(3) for evaluating rtld env vars (LD_XXX) Scan through the set of environment variables during initialization and store values in the corresponding ld_env_var_desc structure, in the single pass at init time. This does not eliminate use of getenv(3) and unsetenv(3) completely, but provides a foundation to do that as the next step. Also organize the scan in a way that makes it easier to support aliases like LD_DEBUG vs. LD_64_DEBUG. Suggested by: arichardson Reviewed by: arichardson, markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D31545 --- libexec/rtld-elf/rtld.c | 144 ++++++++++++++++++++++++++++-------------------- 1 file changed, 83 insertions(+), 61 deletions(-) diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c index 6826dde8a160..39c41fe0ed24 100644 --- a/libexec/rtld-elf/rtld.c +++ b/libexec/rtld-elf/rtld.c @@ -367,82 +367,105 @@ enum { }; struct ld_env_var_desc { - char n[64]; - bool unsecure; + const char *n; + char *val; + const bool unsecure; }; +#define LD_ENV_DESC(var, unsec) \ + [LD_##var] = { .n = #var, .unsecure = unsec } static struct ld_env_var_desc ld_env_vars[] = { - [LD_BIND_NOW] = - { .n = "BIND_NOW", .unsecure = false }, - [LD_PRELOAD] = - { .n = "PRELOAD", .unsecure = true }, - [LD_LIBMAP] = - { .n = "LIBMAP", .unsecure = true }, - [LD_LIBRARY_PATH] = - { .n = "LIBRARY_PATH", .unsecure = true }, - [LD_LIBRARY_PATH_FDS] = - { .n = "LIBRARY_PATH_FDS", .unsecure = true }, - [LD_LIBMAP_DISABLE] = - { .n = "LIBMAP_DISABLE", .unsecure = true }, - [LD_BIND_NOT] = - { .n = "BIND_NOT", .unsecure = true }, - [LD_DEBUG] = - { .n = "DEBUG", .unsecure = true }, - [LD_ELF_HINTS_PATH] = - { .n = "ELF_HINTS_PATH", .unsecure = true }, - [LD_LOADFLTR] = - { .n = "LOADFLTR", .unsecure = true }, - [LD_LIBRARY_PATH_RPATH] = - { .n = "LIBRARY_PATH_RPATH", .unsecure = true }, - [LD_PRELOAD_FDS] = - { .n = "PRELOAD_FDS", .unsecure = true }, - [LD_DYNAMIC_WEAK] = - { .n = "DYNAMIC_WEAK", .unsecure = true }, - [LD_TRACE_LOADED_OBJECTS] = - { .n = "TRACE_LOADED_OBJECTS", .unsecure = false }, - [LD_UTRACE] = - { .n = "UTRACE", .unsecure = false }, - [LD_DUMP_REL_PRE] = - { .n = "DUMP_REL_PRE", .unsecure = false }, - [LD_DUMP_REL_POST] = - { .n = "DUMP_REL_POST", .unsecure = false }, - [LD_TRACE_LOADED_OBJECTS_PROGNAME] = - { .n = "TRACE_LOADED_OBJECTS_PROGNAME", .unsecure = false}, - [LD_TRACE_LOADED_OBJECTS_FMT1] = - { .n = "TRACE_LOADED_OBJECTS_FMT1", .unsecure = false}, - [LD_TRACE_LOADED_OBJECTS_FMT2] = - { .n = "TRACE_LOADED_OBJECTS_FMT2", .unsecure = false}, - [LD_TRACE_LOADED_OBJECTS_ALL] = - { .n = "TRACE_LOADED_OBJECTS_ALL", .unsecure = false}, + LD_ENV_DESC(BIND_NOW, false), + LD_ENV_DESC(PRELOAD, true), + LD_ENV_DESC(LIBMAP, true), + LD_ENV_DESC(LIBRARY_PATH, true), + LD_ENV_DESC(LIBRARY_PATH_FDS, true), + LD_ENV_DESC(LIBMAP_DISABLE, true), + LD_ENV_DESC(BIND_NOT, true), + LD_ENV_DESC(DEBUG, true), + LD_ENV_DESC(ELF_HINTS_PATH, true), + LD_ENV_DESC(LOADFLTR, true), + LD_ENV_DESC(LIBRARY_PATH_RPATH, true), + LD_ENV_DESC(PRELOAD_FDS, true), + LD_ENV_DESC(DYNAMIC_WEAK, true), + LD_ENV_DESC(TRACE_LOADED_OBJECTS, false), + LD_ENV_DESC(UTRACE, false), + LD_ENV_DESC(DUMP_REL_PRE, false), + LD_ENV_DESC(DUMP_REL_POST, false), + LD_ENV_DESC(TRACE_LOADED_OBJECTS_PROGNAME, false), + LD_ENV_DESC(TRACE_LOADED_OBJECTS_FMT1, false), + LD_ENV_DESC(TRACE_LOADED_OBJECTS_FMT2, false), + LD_ENV_DESC(TRACE_LOADED_OBJECTS_ALL, false), }; -static const char * -ld_var(int idx) +static char * +ld_get_env_var(int idx) { - return (ld_env_vars[idx].n); + return (ld_env_vars[idx].val); } static char * -ld_get_env_var(int idx) +rtld_get_env_val(char **env, const char *name, size_t name_len) { - return (getenv(ld_var(idx))); + char **m, *n, *v; + + for (m = env; *m != NULL; m++) { + n = *m; + v = strchr(n, '='); + if (v == NULL) { + /* corrupt environment? */ + continue; + } + if (v - n == (ptrdiff_t)name_len && + strncmp(name, n, name_len) == 0) + return (v + 1); + } + return (NULL); } static void -rtld_init_env_vars(void) +rtld_init_env_vars_for_prefix(char **env, const char *env_prefix) { struct ld_env_var_desc *lvd; - size_t sz; + size_t prefix_len, nlen; + char **m, *n, *v; int i; - sz = strlen(ld_env_prefix); - for (i = 0; i < (int)nitems(ld_env_vars); i++) { - lvd = &ld_env_vars[i]; - memmove(lvd->n + sz, lvd->n, strlen(lvd->n) + 1); - memcpy(lvd->n, ld_env_prefix, sz); + prefix_len = strlen(env_prefix); + for (m = env; *m != NULL; m++) { + n = *m; + if (strncmp(env_prefix, n, prefix_len) != 0) { + /* Not a rtld environment variable. */ + continue; + } + n += prefix_len; + v = strchr(n, '='); + if (v == NULL) { + /* corrupt environment? */ + continue; + } + for (i = 0; i < (int)nitems(ld_env_vars); i++) { + lvd = &ld_env_vars[i]; + if (lvd->val != NULL) { + /* Saw higher-priority variable name already. */ + continue; + } + nlen = strlen(lvd->n); + if (v - n == (ptrdiff_t)nlen && + strncmp(lvd->n, n, nlen) == 0) { + lvd->val = v + 1; + break; + } + } } } +static void +rtld_init_env_vars(char **env) +{ + rtld_init_env_vars_for_prefix(env, ld_env_prefix); +} + /* * Main entry point for dynamic linking. The first argument is the * stack pointer. The stack is expected to be laid out as described @@ -548,7 +571,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) direct_exec = false; md_abi_variant_hook(aux_info); - rtld_init_env_vars(); + rtld_init_env_vars(env); fd = -1; if (aux_info[AT_EXECFD] != NULL) { @@ -667,12 +690,11 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) if (!trust) { for (i = 0; i < (int)nitems(ld_env_vars); i++) { lvd = &ld_env_vars[i]; - if (lvd->unsecure && unsetenv(lvd->n)) { - _rtld_error("environment corrupt; aborting"); - rtld_die(); - } + if (lvd->unsecure) + lvd->val = NULL; } } + ld_debug = ld_get_env_var(LD_DEBUG); if (ld_bind_now == NULL) ld_bind_not = ld_get_env_var(LD_BIND_NOT) != NULL;