From eb59c7b43dd5c64c38e4c3cd21e7ad75d8d29cb0 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Mon, 6 May 2024 13:18:48 -0300 Subject: [PATCH] elf: Make glibc.rtld.enable_secure ignore alias environment variables Tunable with environment variables aliases are also ignored if glibc.rtld.enable_secure is enabled. The tunable parsing is also optimized a bit, where the loop that checks each environment variable only checks for the tunables with aliases instead of all tables. Checked on aarch64-linux-gnu and x86_64-linux-gnu. Reviewed-by: Siddhesh Poyarekar --- elf/dl-tunables.c | 38 ++++++--- elf/tst-tunables-enable_secure.c | 136 +++++++++++++++++++++++++++---- scripts/gen-tunables.awk | 16 +++- 3 files changed, 165 insertions(+), 25 deletions(-) diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 63cf8c7ab5..147cc4cf23 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -300,6 +300,9 @@ __tunables_init (char **envp) if (__libc_enable_secure) return; + enum { tunable_num_env_alias = array_length (tunable_env_alias_list) }; + struct tunable_toset_t tunables_env_alias[tunable_num_env_alias] = { 0 }; + while ((envp = get_next_env (envp, &envname, &envval, &prev_envp)) != NULL) { /* The environment variable is allocated on the stack by the kernel, so @@ -311,29 +314,44 @@ __tunables_init (char **envp) continue; } - for (int i = 0; i < tunables_list_size; i++) + for (int i = 0; i < tunable_num_env_alias; i++) { - tunable_t *cur = &tunable_list[i]; - - /* Skip over tunables that have either been set already or should be - skipped. */ - if (cur->initialized || cur->env_alias[0] == '\0') - continue; - + tunable_t *cur = &tunable_list[tunable_env_alias_list[i]]; const char *name = cur->env_alias; - /* We have a match. Initialize and move on to the next line. */ + if (name[0] == '\0') + continue; + if (tunable_is_name (name, envname)) { size_t envvallen = 0; /* The environment variable is always null-terminated. */ for (const char *p = envval; *p != '\0'; p++, envvallen++); - tunable_initialize (cur, envval, envvallen); + tunables_env_alias[i] = + (struct tunable_toset_t) { cur, envval, envvallen }; break; } } } + + /* Check if glibc.rtld.enable_secure was set and skip over the environment + variables aliases. */ + if (__libc_enable_secure) + return; + + for (int i = 0; i < tunable_num_env_alias; i++) + { + /* Skip over tunables that have either been set or already initialized. */ + if (tunables_env_alias[i].t == NULL + || tunables_env_alias[i].t->initialized) + continue; + + if (!tunable_initialize (tunables_env_alias[i].t, + tunables_env_alias[i].value, + tunables_env_alias[i].len)) + parse_tunable_print_error (&tunables_env_alias[i]); + } } void diff --git a/elf/tst-tunables-enable_secure.c b/elf/tst-tunables-enable_secure.c index f5db1c84e9..99a065e8db 100644 --- a/elf/tst-tunables-enable_secure.c +++ b/elf/tst-tunables-enable_secure.c @@ -17,6 +17,10 @@ . */ #include +/* The test uses the tunable_env_alias_list size, which is only exported for + ld.so. This will result in a copy of tunable_list and + tunable_env_alias_list, which is ununsed by the test itself. */ +#define TUNABLES_INTERNAL 1 #include #include #include @@ -34,6 +38,8 @@ static int restart; static const struct test_t { const char *env; + const char *extraenv; + bool check_multiple; int32_t expected_malloc_check; int32_t expected_enable_secure; } tests[] = @@ -41,39 +47,124 @@ static const struct test_t /* Expected tunable format. */ /* Tunables should be ignored if enable_secure is set. */ { - "glibc.malloc.check=2:glibc.rtld.enable_secure=1", + "GLIBC_TUNABLES=glibc.malloc.check=2:glibc.rtld.enable_secure=1", + NULL, + false, 0, 1, }, /* Tunables should be ignored if enable_secure is set. */ { - "glibc.rtld.enable_secure=1:glibc.malloc.check=2", + "GLIBC_TUNABLES=glibc.rtld.enable_secure=1:glibc.malloc.check=2", + NULL, + false, 0, 1, }, /* Tunables should be set if enable_secure is unset. */ { - "glibc.rtld.enable_secure=0:glibc.malloc.check=2", + "GLIBC_TUNABLES=glibc.rtld.enable_secure=0:glibc.malloc.check=2", + NULL, + false, 2, 0, }, + /* Tunables should be ignored if enable_secure is set. */ + { + "GLIBC_TUNABLES=glibc.malloc.check=2:glibc.rtld.enable_secure=1", + "MALLOC_CHECK_=2", + false, + 0, + 1, + }, + /* Same as before, but with enviroment alias prior GLIBC_TUNABLES. */ + { + "MALLOC_CHECK_=2", + "GLIBC_TUNABLES=glibc.malloc.check=2:glibc.rtld.enable_secure=1", + false, + 0, + 1, + }, + /* Tunables should be ignored if enable_secure is set. */ + { + "GLIBC_TUNABLES=glibc.rtld.enable_secure=1:glibc.malloc.check=2", + "MALLOC_CHECK_=2", + false, + 0, + 1, + }, + { + "MALLOC_CHECK_=2", + "GLIBC_TUNABLES=glibc.rtld.enable_secure=1:glibc.malloc.check=2", + false, + 0, + 1, + }, + /* Tunables should be set if enable_secure is unset. */ + { + "GLIBC_TUNABLES=glibc.rtld.enable_secure=0:glibc.malloc.check=2", + /* Tunable have precedence over the environment variable. */ + "MALLOC_CHECK_=1", + false, + 2, + 0, + }, + { + "MALLOC_CHECK_=1", + "GLIBC_TUNABLES=glibc.rtld.enable_secure=0:glibc.malloc.check=2", + /* Tunable have precedence over the environment variable. */ + false, + 2, + 0, + }, + /* Tunables should be set if enable_secure is unset. */ + { + "GLIBC_TUNABLES=glibc.rtld.enable_secure=0", + /* Tunable have precedence over the environment variable. */ + "MALLOC_CHECK_=1", + false, + 1, + 0, + }, + /* Tunables should be set if enable_secure is unset. */ + { + "GLIBC_TUNABLES=glibc.rtld.enable_secure=0", + /* Tunable have precedence over the environment variable. */ + "MALLOC_CHECK_=1", + false, + 1, + 0, + }, + /* Check with tunables environment variable alias set multiple times. */ + { + "GLIBC_TUNABLES=glibc.rtld.enable_secure=1:glibc.malloc.check=2", + "MALLOC_CHECK_=2", + true, + 0, + 1, + }, + /* Tunables should be set if enable_secure is unset. */ + { + "GLIBC_TUNABLES=glibc.rtld.enable_secure=0", + /* Tunable have precedence over the environment variable. */ + "MALLOC_CHECK_=1", + true, + 1, + 0, + }, }; static int handle_restart (int i) { if (tests[i].expected_enable_secure == 1) - { - TEST_COMPARE (1, __libc_enable_secure); - } + TEST_COMPARE (1, __libc_enable_secure); else - { - TEST_COMPARE (tests[i].expected_malloc_check, - TUNABLE_GET_FULL (glibc, malloc, check, int32_t, NULL)); - TEST_COMPARE (tests[i].expected_enable_secure, - TUNABLE_GET_FULL (glibc, rtld, enable_secure, int32_t, - NULL)); - } + TEST_COMPARE (tests[i].expected_enable_secure, + TUNABLE_GET_FULL (glibc, rtld, enable_secure, int32_t, + NULL)); + TEST_COMPARE (tests[i].expected_malloc_check, + TUNABLE_GET_FULL (glibc, malloc, check, int32_t, NULL)); return 0; } @@ -106,14 +197,31 @@ do_test (int argc, char *argv[]) spargv[i] = NULL; } + enum { tunable_num_env_alias = array_length (tunable_env_alias_list) }; + for (int i = 0; i < array_length (tests); i++) { snprintf (nteststr, sizeof nteststr, "%d", i); printf ("[%d] Spawned test for %s\n", i, tests[i].env); setenv ("GLIBC_TUNABLES", tests[i].env, 1); + + char *envp[2 + tunable_num_env_alias + 1] = + { + (char *) tests[i].env, + (char *) tests[i].extraenv, + NULL, + }; + if (tests[i].check_multiple) + { + int j; + for (j=0; j < tunable_num_env_alias; j++) + envp[j + 2] = (char *) tests[i].extraenv; + envp[j + 2] = NULL; + } + struct support_capture_subprocess result - = support_capture_subprogram (spargv[0], spargv, NULL); + = support_capture_subprogram (spargv[0], spargv, envp); support_capture_subprocess_check (&result, "tst-tunables-enable_secure", 0, sc_allow_stderr); support_capture_subprocess_free (&result); diff --git a/scripts/gen-tunables.awk b/scripts/gen-tunables.awk index 9f5336381e..fc3b41376f 100644 --- a/scripts/gen-tunables.awk +++ b/scripts/gen-tunables.awk @@ -156,7 +156,7 @@ END { print "# define TUNABLE_ALIAS_MAX " (max_alias_len + 1) print "# include \"dl-tunable-types.h\"" # Finally, the tunable list. - print "static tunable_t tunable_list[] attribute_relro = {" + print "static tunable_t tunable_list[] attribute_relro __attribute_used__ = {" for (tnm in types) { split (tnm, indices, SUBSEP); t = indices[1]; @@ -168,5 +168,19 @@ END { default_val[t,n,m], env_alias[t,n,m]); } print "};" + + # Map of tunable with environment variables aliases used during parsing. */ + print "\nstatic const tunable_id_t tunable_env_alias_list[] =" + printf "{\n" + for (tnm in types) { + split (tnm, indices, SUBSEP); + t = indices[1]; + n = indices[2]; + m = indices[3]; + if (env_alias[t,n,m] != "{0}") { + printf (" TUNABLE_ENUM_NAME(%s, %s, %s),\n", t, n, m); + } + } + printf "};\n" print "#endif" }