From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1791) id 028EB3857B86; Tue, 5 Dec 2023 20:34:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 028EB3857B86 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1701808455; bh=yHo2l7Jx1oZkoQ3q897EfLGH3gN+20s6QXPDvhZfvaY=; h=From:To:Subject:Date:From; b=ArXtAw/jM9czfZ4tD4KMMGX5FxVYZrjO+8aCs9xCITVjlff5G2EMMFbEhuPiSfh2/ IvcCqyO2A+eyIjOe6fSW/fQbKVFvCotc4Ehqk9s1k2saluSYbPVDdGygYJX9BNIwUu ZpqWy7jJAVJ5vY0LbXNdDF/5IHE0Cp6xg0rFodxI= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc] elf: Refactor process_envvars X-Act-Checkin: glibc X-Git-Author: Adhemerval Zanella X-Git-Refname: refs/heads/master X-Git-Oldrev: 61d848b554c8dd1f017b9d187b2a2f6675dbdbe4 X-Git-Newrev: 4369019520a3396304f5382f29da667cebb98695 Message-Id: <20231205203415.028EB3857B86@sourceware.org> Date: Tue, 5 Dec 2023 20:34:15 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=4369019520a3396304f5382f29da667cebb98695 commit 4369019520a3396304f5382f29da667cebb98695 Author: Adhemerval Zanella Date: Wed Nov 22 17:43:25 2023 -0300 elf: Refactor process_envvars It splits between process_envvars_secure and process_envvars_default, with the former used to process arguments for __libc_enable_secure. It does not have any semantic change, just simplify the code so there is no need to handle __libc_enable_secure on each len switch. Checked on x86_64-linux-gnu and aarch64-linux-gnu. Reviewed-by: Siddhesh Poyarekar Diff: --- elf/rtld.c | 132 +++++++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 84 insertions(+), 48 deletions(-) diff --git a/elf/rtld.c b/elf/rtld.c index d9a6c33b31..f0b0f3328d 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -2533,7 +2533,67 @@ a filename can be specified using the LD_DEBUG_OUTPUT environment variable.\n"); } static void -process_envvars (struct dl_main_state *state) +process_envvars_secure (struct dl_main_state *state) +{ + char **runp = _environ; + char *envline; + + while ((envline = _dl_next_ld_env_entry (&runp)) != NULL) + { + size_t len = 0; + + while (envline[len] != '\0' && envline[len] != '=') + ++len; + + if (envline[len] != '=') + /* This is a "LD_" variable at the end of the string without + a '=' character. Ignore it since otherwise we will access + invalid memory below. */ + continue; + + switch (len) + { + case 5: + /* For __libc_enable_secure mode, audit pathnames containing slashes + are ignored. Also, shared audit objects are only loaded only from + the standard search directories and only if they have set-user-ID + mode bit enabled. */ + if (memcmp (envline, "AUDIT", 5) == 0) + audit_list_add_string (&state->audit_list, &envline[6]); + break; + + case 7: + /* For __libc_enable_secure mode, preload pathnames containing slashes + are ignored. Also, shared objects are only preloaded from the + standard search directories and only if they have set-user-ID mode + bit enabled. */ + if (memcmp (envline, "PRELOAD", 7) == 0) + state->preloadlist = &envline[8]; + break; + } + } + + /* Extra security for SUID binaries. Remove all dangerous environment + variables. */ + const char *nextp = UNSECURE_ENVVARS; + do + { + unsetenv (nextp); + nextp = strchr (nextp, '\0') + 1; + } + while (*nextp != '\0'); + + if (GLRO(dl_debug_mask) != 0 + || GLRO(dl_verbose) != 0 + || GLRO(dl_lazy) != 1 + || GLRO(dl_bind_not) != 0 + || state->mode != rtld_mode_normal + || state->version_info) + _exit (5); +} + +static void +process_envvars_default (struct dl_main_state *state) { char **runp = _environ; char *envline; @@ -2556,15 +2616,13 @@ process_envvars (struct dl_main_state *state) { case 4: /* Warning level, verbose or not. */ - if (!__libc_enable_secure - && memcmp (envline, "WARN", 4) == 0) + if (memcmp (envline, "WARN", 4) == 0) GLRO(dl_verbose) = envline[5] != '\0'; break; case 5: /* Debugging of the dynamic linker? */ - if (!__libc_enable_secure - && memcmp (envline, "DEBUG", 5) == 0) + if (memcmp (envline, "DEBUG", 5) == 0) { process_dl_debug (state, &envline[6]); break; @@ -2579,8 +2637,7 @@ process_envvars (struct dl_main_state *state) case 7: /* Print information about versions. */ - if (!__libc_enable_secure - && memcmp (envline, "VERBOSE", 7) == 0) + if (memcmp (envline, "VERBOSE", 7) == 0) { state->version_info = envline[8] != '\0'; break; @@ -2597,43 +2654,37 @@ process_envvars (struct dl_main_state *state) } /* Which shared object shall be profiled. */ - if (!__libc_enable_secure - && memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0') + if (memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0') GLRO(dl_profile) = &envline[8]; break; case 8: /* Do we bind early? */ - if (!__libc_enable_secure - && memcmp (envline, "BIND_NOW", 8) == 0) + if (memcmp (envline, "BIND_NOW", 8) == 0) { GLRO(dl_lazy) = envline[9] == '\0'; break; } - if (! __libc_enable_secure - && memcmp (envline, "BIND_NOT", 8) == 0) + if (memcmp (envline, "BIND_NOT", 8) == 0) GLRO(dl_bind_not) = envline[9] != '\0'; break; case 9: /* Test whether we want to see the content of the auxiliary array passed up from the kernel. */ - if (!__libc_enable_secure - && memcmp (envline, "SHOW_AUXV", 9) == 0) + if (memcmp (envline, "SHOW_AUXV", 9) == 0) _dl_show_auxv (); break; case 11: /* Path where the binary is found. */ - if (!__libc_enable_secure - && memcmp (envline, "ORIGIN_PATH", 11) == 0) + if (memcmp (envline, "ORIGIN_PATH", 11) == 0) GLRO(dl_origin_path) = &envline[12]; break; case 12: /* The library search path. */ - if (!__libc_enable_secure - && memcmp (envline, "LIBRARY_PATH", 12) == 0) + if (memcmp (envline, "LIBRARY_PATH", 12) == 0) { state->library_path = &envline[13]; state->library_path_source = "LD_LIBRARY_PATH"; @@ -2641,30 +2692,26 @@ process_envvars (struct dl_main_state *state) } /* Where to place the profiling data file. */ - if (!__libc_enable_secure - && memcmp (envline, "DEBUG_OUTPUT", 12) == 0) + if (memcmp (envline, "DEBUG_OUTPUT", 12) == 0) { debug_output = &envline[13]; break; } - if (!__libc_enable_secure - && memcmp (envline, "DYNAMIC_WEAK", 12) == 0) + if (memcmp (envline, "DYNAMIC_WEAK", 12) == 0) GLRO(dl_dynamic_weak) = 1; break; case 14: /* Where to place the profiling data file. */ - if (!__libc_enable_secure - && memcmp (envline, "PROFILE_OUTPUT", 14) == 0 + if (memcmp (envline, "PROFILE_OUTPUT", 14) == 0 && envline[15] != '\0') GLRO(dl_profile_output) = &envline[15]; break; case 20: /* The mode of the dynamic linker can be set. */ - if (!__libc_enable_secure - && memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0) + if (memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0) { state->mode = rtld_mode_trace; state->mode_trace_program @@ -2674,30 +2721,10 @@ process_envvars (struct dl_main_state *state) } } - /* Extra security for SUID binaries. Remove all dangerous environment - variables. */ - if (__glibc_unlikely (__libc_enable_secure)) - { - const char *nextp = UNSECURE_ENVVARS; - do - { - unsetenv (nextp); - nextp = strchr (nextp, '\0') + 1; - } - while (*nextp != '\0'); - - if (GLRO(dl_debug_mask) != 0 - || GLRO(dl_verbose) != 0 - || GLRO(dl_lazy) != 1 - || GLRO(dl_bind_not) != 0 - || state->mode != rtld_mode_normal - || state->version_info) - _exit (5); - } /* If we have to run the dynamic linker in debugging mode and the LD_DEBUG_OUTPUT environment variable is given, we write the debug messages to this file. */ - else if (GLRO(dl_debug_mask) != 0 && debug_output != NULL) + if (GLRO(dl_debug_mask) != 0 && debug_output != NULL) { const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW; size_t name_len = strlen (debug_output); @@ -2716,6 +2743,15 @@ process_envvars (struct dl_main_state *state) } } +static void +process_envvars (struct dl_main_state *state) +{ + if (__glibc_unlikely (__libc_enable_secure)) + process_envvars_secure (state); + else + process_envvars_default (state); +} + #if HP_TIMING_INLINE static void print_statistics_item (const char *title, hp_timing_t time,