diff options
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/dl-main.h | 98 | ||||
| -rw-r--r-- | elf/rtld.c | 155 |
2 files changed, 157 insertions, 96 deletions
diff --git a/elf/dl-main.h b/elf/dl-main.h new file mode 100644 index 0000000000..bcc9bcf2e8 --- /dev/null +++ b/elf/dl-main.h @@ -0,0 +1,98 @@ +/* Information collection during ld.so startup. + Copyright (C) 1995-2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#ifndef _DL_MAIN +#define _DL_MAIN + +#include <limits.h> + +/* Length limits for names and paths, to protect the dynamic linker, + particularly when __libc_enable_secure is active. */ +#ifdef NAME_MAX +# define SECURE_NAME_LIMIT NAME_MAX +#else +# define SECURE_NAME_LIMIT 255 +#endif +#ifdef PATH_MAX +# define SECURE_PATH_LIMIT PATH_MAX +#else +# define SECURE_PATH_LIMIT 1024 +#endif + +/* Strings containing colon-separated lists of audit modules. */ +struct audit_list +{ + /* Array of strings containing colon-separated path lists. Each + audit module needs its own namespace, so pre-allocate the largest + possible list. */ + const char *audit_strings[DL_NNS]; + + /* Number of entries added to audit_strings. */ + size_t length; + + /* Index into the audit_strings array (for the iteration phase). */ + size_t current_index; + + /* Tail of audit_strings[current_index] which still needs + processing. */ + const char *current_tail; + + /* Scratch buffer for returning a name which is part of the strings + in audit_strings. */ + char fname[SECURE_NAME_LIMIT]; +}; + +/* This is a list of all the modes the dynamic loader can be in. */ +enum rtld_mode + { + rtld_mode_normal, rtld_mode_list, rtld_mode_verify, rtld_mode_trace, + }; + +/* Aggregated state information extracted from environment variables + and the ld.so command line. */ +struct dl_main_state +{ + struct audit_list audit_list; + + /* The library search path. */ + const char *library_path; + + /* The list preloaded objects from LD_PRELOAD. */ + const char *preloadlist; + + /* The preload list passed as a command argument. */ + const char *preloadarg; + + enum rtld_mode mode; + + /* True if any of the debugging options is enabled. */ + bool any_debug; + + /* True if information about versions has to be printed. */ + bool version_info; +}; + +/* Helper function to invoke _dl_init_paths with the right arguments + from *STATE. */ +static inline void +call_init_paths (const struct dl_main_state *state) +{ + _dl_init_paths (state->library_path); +} + +#endif /* _DL_MAIN */ diff --git a/elf/rtld.c b/elf/rtld.c index 9918fda05e..8e35c3a330 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -47,6 +47,7 @@ #include <not-cancel.h> #include <array_length.h> #include <libc-early-init.h> +#include <dl-main.h> #include <assert.h> @@ -111,42 +112,6 @@ static void print_missing_version (int errcode, const char *objname, /* Print the various times we collected. */ static void print_statistics (const hp_timing_t *total_timep); -/* Length limits for names and paths, to protect the dynamic linker, - particularly when __libc_enable_secure is active. */ -#ifdef NAME_MAX -# define SECURE_NAME_LIMIT NAME_MAX -#else -# define SECURE_NAME_LIMIT 255 -#endif -#ifdef PATH_MAX -# define SECURE_PATH_LIMIT PATH_MAX -#else -# define SECURE_PATH_LIMIT 1024 -#endif - -/* Strings containing colon-separated lists of audit modules. */ -struct audit_list -{ - /* Array of strings containing colon-separated path lists. Each - audit module needs its own namespace, so pre-allocate the largest - possible list. */ - const char *audit_strings[DL_NNS]; - - /* Number of entries added to audit_strings. */ - size_t length; - - /* Index into the audit_strings array (for the iteration phase). */ - size_t current_index; - - /* Tail of audit_strings[current_index] which still needs - processing. */ - const char *current_tail; - - /* Scratch buffer for returning a name which is part of the strings - in audit_strings. */ - char fname[SECURE_NAME_LIMIT]; -}; - /* Creates an empty audit list. */ static void audit_list_init (struct audit_list *); @@ -167,13 +132,13 @@ static void audit_list_add_dynamic_tag (struct audit_list *, audit_list_add_dynamic_tags calls. */ static const char *audit_list_next (struct audit_list *); -/* This is a list of all the modes the dynamic loader can be in. */ -enum mode { normal, list, verify, trace }; +/* Initialize *STATE with the defaults. */ +static void dl_main_state_init (struct dl_main_state *state); /* Process all environments variables the dynamic linker must recognize. Since all of them start with `LD_' we are a bit smarter while finding all the entries. */ -static void process_envvars (enum mode *modep, struct audit_list *); +static void process_envvars (struct dl_main_state *state); #ifdef DL_ARGV_NOT_RELRO int _dl_argc attribute_hidden; @@ -316,6 +281,18 @@ audit_list_count (struct audit_list *list) return naudit; } +static void +dl_main_state_init (struct dl_main_state *state) +{ + audit_list_init (&state->audit_list); + state->library_path = NULL; + state->preloadlist = NULL; + state->preloadarg = NULL; + state->mode = rtld_mode_normal; + state->any_debug = false; + state->version_info = false; +} + #ifndef HAVE_INLINED_SYSCALLS /* Set nonzero during loading and initialization of executable and libraries, cleared before the executable's entry point runs. This @@ -900,15 +877,6 @@ security_init (void) #include <setup-vdso.h> -/* The library search path. */ -static const char *library_path attribute_relro; -/* The list preloaded objects. */ -static const char *preloadlist attribute_relro; -/* Nonzero if information about versions has to be printed. */ -static int version_info attribute_relro; -/* The preload list passed as a command argument. */ -static const char *preloadarg attribute_relro; - /* The LD_PRELOAD environment variable gives list of libraries separated by white space or colons that are loaded before the executable's dependencies and prepended to the global scope list. @@ -1150,7 +1118,6 @@ dl_main (const ElfW(Phdr) *phdr, ElfW(auxv_t) *auxv) { const ElfW(Phdr) *ph; - enum mode mode; struct link_map *main_map; size_t file_size; char *file; @@ -1160,8 +1127,8 @@ dl_main (const ElfW(Phdr) *phdr, bool rtld_is_main = false; void *tcbp = NULL; - struct audit_list audit_list; - audit_list_init (&audit_list); + struct dl_main_state state; + dl_main_state_init (&state); GL(dl_init_static_tls) = &_dl_nothread_init_static_tls; @@ -1176,7 +1143,7 @@ dl_main (const ElfW(Phdr) *phdr, GL(dl_make_stack_executable_hook) = &_dl_make_stack_executable; /* Process the environment variable which control the behaviour. */ - process_envvars (&mode, &audit_list); + process_envvars (&state); #ifndef HAVE_INLINED_SYSCALLS /* Set up a flag which tells we are just starting. */ @@ -1210,7 +1177,7 @@ dl_main (const ElfW(Phdr) *phdr, while (_dl_argc > 1) if (! strcmp (_dl_argv[1], "--list")) { - mode = list; + state.mode = rtld_mode_list; GLRO(dl_lazy) = -1; /* This means do no dependency analysis. */ ++_dl_skip_args; @@ -1219,7 +1186,7 @@ dl_main (const ElfW(Phdr) *phdr, } else if (! strcmp (_dl_argv[1], "--verify")) { - mode = verify; + state.mode = rtld_mode_verify; ++_dl_skip_args; --_dl_argc; @@ -1235,7 +1202,7 @@ dl_main (const ElfW(Phdr) *phdr, else if (! strcmp (_dl_argv[1], "--library-path") && _dl_argc > 2) { - library_path = _dl_argv[2]; + state.library_path = _dl_argv[2]; _dl_skip_args += 2; _dl_argc -= 2; @@ -1252,7 +1219,7 @@ dl_main (const ElfW(Phdr) *phdr, } else if (! strcmp (_dl_argv[1], "--audit") && _dl_argc > 2) { - audit_list_add_string (&audit_list, _dl_argv[2]); + audit_list_add_string (&state.audit_list, _dl_argv[2]); _dl_skip_args += 2; _dl_argc -= 2; @@ -1260,7 +1227,7 @@ dl_main (const ElfW(Phdr) *phdr, } else if (! strcmp (_dl_argv[1], "--preload") && _dl_argc > 2) { - preloadarg = _dl_argv[2]; + state.preloadarg = _dl_argv[2]; _dl_skip_args += 2; _dl_argc -= 2; _dl_argv += 2; @@ -1328,7 +1295,7 @@ of this helper program; chances are you did not intend to run this program.\n\ break; } - if (__builtin_expect (mode, normal) == verify) + if (__glibc_unlikely (state.mode == rtld_mode_verify)) { const char *objname; const char *err_str = NULL; @@ -1357,7 +1324,7 @@ of this helper program; chances are you did not intend to run this program.\n\ /* Now the map for the main executable is available. */ main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded; - if (__builtin_expect (mode, normal) == normal + if (__glibc_likely (state.mode == rtld_mode_normal) && GL(dl_rtld_map).l_info[DT_SONAME] != NULL && main_map->l_info[DT_SONAME] != NULL && strcmp ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB]) @@ -1604,7 +1571,7 @@ of this helper program; chances are you did not intend to run this program.\n\ _dl_setup_hash (main_map); } - if (__builtin_expect (mode, normal) == verify) + if (__glibc_unlikely (state.mode == rtld_mode_verify)) { /* We were called just to verify that this is a dynamic executable using us as the program interpreter. Exit with an @@ -1634,7 +1601,7 @@ of this helper program; chances are you did not intend to run this program.\n\ /* Initialize the data structures for the search paths for shared objects. */ - _dl_init_paths (library_path); + call_init_paths (&state); /* Initialize _r_debug. */ struct r_debug *r = _dl_debug_initialize (GL(dl_rtld_map).l_addr, @@ -1699,14 +1666,14 @@ of this helper program; chances are you did not intend to run this program.\n\ /* Assign a module ID. Do this before loading any audit modules. */ GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid (); - audit_list_add_dynamic_tag (&audit_list, main_map, DT_AUDIT); - audit_list_add_dynamic_tag (&audit_list, main_map, DT_DEPAUDIT); + audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_AUDIT); + audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_DEPAUDIT); /* If we have auditing DSOs to load, do it now. */ bool need_security_init = true; - if (audit_list.length > 0) + if (state.audit_list.length > 0) { - size_t naudit = audit_list_count (&audit_list); + size_t naudit = audit_list_count (&state.audit_list); /* Since we start using the auditing DSOs right away we need to initialize the data structures now. */ @@ -1719,7 +1686,7 @@ of this helper program; chances are you did not intend to run this program.\n\ security_init (); need_security_init = false; - load_audit_modules (main_map, &audit_list); + load_audit_modules (main_map, &state.audit_list); /* The count based on audit strings may overestimate the number of audit modules that got loaded, but not underestimate. */ @@ -1774,19 +1741,21 @@ of this helper program; chances are you did not intend to run this program.\n\ struct link_map **preloads = NULL; unsigned int npreloads = 0; - if (__glibc_unlikely (preloadlist != NULL)) + if (__glibc_unlikely (state.preloadlist != NULL)) { RTLD_TIMING_VAR (start); rtld_timer_start (&start); - npreloads += handle_preload_list (preloadlist, main_map, "LD_PRELOAD"); + npreloads += handle_preload_list (state.preloadlist, main_map, + "LD_PRELOAD"); rtld_timer_accum (&load_time, start); } - if (__glibc_unlikely (preloadarg != NULL)) + if (__glibc_unlikely (state.preloadarg != NULL)) { RTLD_TIMING_VAR (start); rtld_timer_start (&start); - npreloads += handle_preload_list (preloadarg, main_map, "--preload"); + npreloads += handle_preload_list (state.preloadarg, main_map, + "--preload"); rtld_timer_accum (&load_time, start); } @@ -1893,7 +1862,8 @@ of this helper program; chances are you did not intend to run this program.\n\ { RTLD_TIMING_VAR (start); rtld_timer_start (&start); - _dl_map_object_deps (main_map, preloads, npreloads, mode == trace, 0); + _dl_map_object_deps (main_map, preloads, npreloads, + state.mode == rtld_mode_trace, 0); rtld_timer_accum (&load_time, start); } @@ -1920,7 +1890,7 @@ of this helper program; chances are you did not intend to run this program.\n\ rtld_multiple_ref = true; GL(dl_rtld_map).l_prev = main_map->l_searchlist.r_list[i - 1]; - if (__builtin_expect (mode, normal) == normal) + if (__glibc_likely (state.mode == rtld_mode_normal)) { GL(dl_rtld_map).l_next = (i + 1 < main_map->l_searchlist.r_nlist ? main_map->l_searchlist.r_list[i + 1] @@ -1953,8 +1923,8 @@ of this helper program; chances are you did not intend to run this program.\n\ versions we need. */ { struct version_check_args args; - args.doexit = mode == normal; - args.dotrace = mode == trace; + args.doexit = state.mode == rtld_mode_normal; + args.dotrace = state.mode == rtld_mode_trace; _dl_receive_error (print_missing_version, version_check_doit, &args); } @@ -1974,7 +1944,7 @@ of this helper program; chances are you did not intend to run this program.\n\ earlier. */ security_init (); - if (__builtin_expect (mode, normal) != normal) + if (__glibc_unlikely (state.mode != rtld_mode_normal)) { /* We were run just to list the shared libraries. It is important that we do this before real relocation, because the @@ -2076,7 +2046,7 @@ of this helper program; chances are you did not intend to run this program.\n\ (size_t) l->l_map_start); } - if (__builtin_expect (mode, trace) != trace) + if (__glibc_unlikely (state.mode != rtld_mode_trace)) for (i = 1; i < (unsigned int) _dl_argc; ++i) { const ElfW(Sym) *ref = NULL; @@ -2130,7 +2100,7 @@ of this helper program; chances are you did not intend to run this program.\n\ } } #define VERNEEDTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (DT_VERNEED)) - if (version_info) + if (state.version_info) { /* Print more information. This means here, print information about the versions needed. */ @@ -2492,13 +2462,10 @@ print_missing_version (int errcode __attribute__ ((unused)), objname, errstring); } -/* Nonzero if any of the debugging options is enabled. */ -static int any_debug attribute_relro; - /* Process the string given as the parameter which explains which debugging options are enabled. */ static void -process_dl_debug (const char *dl_debug) +process_dl_debug (struct dl_main_state *state, const char *dl_debug) { /* When adding new entries make sure that the maximal length of a name is correctly handled in the LD_DEBUG_HELP code below. */ @@ -2555,7 +2522,7 @@ process_dl_debug (const char *dl_debug) && memcmp (dl_debug, debopts[cnt].name, len) == 0) { GLRO(dl_debug_mask) |= debopts[cnt].mask; - any_debug = 1; + state->any_debug = true; break; } @@ -2609,11 +2576,10 @@ extern char **_environ attribute_hidden; static void -process_envvars (enum mode *modep, struct audit_list *audit_list) +process_envvars (struct dl_main_state *state) { char **runp = _environ; char *envline; - enum mode mode = normal; char *debug_output = NULL; /* This is the default place for profiling data file. */ @@ -2645,25 +2611,25 @@ process_envvars (enum mode *modep, struct audit_list *audit_list) /* Debugging of the dynamic linker? */ if (memcmp (envline, "DEBUG", 5) == 0) { - process_dl_debug (&envline[6]); + process_dl_debug (state, &envline[6]); break; } if (memcmp (envline, "AUDIT", 5) == 0) - audit_list_add_string (audit_list, &envline[6]); + audit_list_add_string (&state->audit_list, &envline[6]); break; case 7: /* Print information about versions. */ if (memcmp (envline, "VERBOSE", 7) == 0) { - version_info = envline[8] != '\0'; + state->version_info = envline[8] != '\0'; break; } /* List of objects to be preloaded. */ if (memcmp (envline, "PRELOAD", 7) == 0) { - preloadlist = &envline[8]; + state->preloadlist = &envline[8]; break; } @@ -2712,7 +2678,7 @@ process_envvars (enum mode *modep, struct audit_list *audit_list) if (!__libc_enable_secure && memcmp (envline, "LIBRARY_PATH", 12) == 0) { - library_path = &envline[13]; + state->library_path = &envline[13]; break; } @@ -2754,7 +2720,7 @@ process_envvars (enum mode *modep, struct audit_list *audit_list) /* The mode of the dynamic linker can be set. */ if (memcmp (envline, "TRACE_PRELINKING", 16) == 0) { - mode = trace; + state->mode = rtld_mode_trace; GLRO(dl_verbose) = 1; GLRO(dl_debug_mask) |= DL_DEBUG_PRELINK; GLRO(dl_trace_prelink) = &envline[17]; @@ -2764,7 +2730,7 @@ process_envvars (enum mode *modep, struct audit_list *audit_list) case 20: /* The mode of the dynamic linker can be set. */ if (memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0) - mode = trace; + state->mode = rtld_mode_trace; break; /* We might have some extra environment variable to handle. This @@ -2777,9 +2743,6 @@ process_envvars (enum mode *modep, struct audit_list *audit_list) } } - /* The caller wants this information. */ - *modep = mode; - /* Extra security for SUID binaries. Remove all dangerous environment variables. */ if (__builtin_expect (__libc_enable_secure, 0)) @@ -2808,13 +2771,13 @@ process_envvars (enum mode *modep, struct audit_list *audit_list) GLRO(dl_debug_mask) = 0; } - if (mode != normal) + if (state->mode != rtld_mode_normal) _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 (any_debug && debug_output != NULL) + else if (state->any_debug && debug_output != NULL) { const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW; size_t name_len = strlen (debug_output); |