diff options
| -rw-r--r-- | csu/init-first.c | 4 | ||||
| -rw-r--r-- | csu/libc-start.c | 5 | ||||
| -rw-r--r-- | elf/Makefile | 5 | ||||
| -rw-r--r-- | elf/Versions | 1 | ||||
| -rw-r--r-- | elf/dl-call-libc-early-init.c | 41 | ||||
| -rw-r--r-- | elf/dl-load.c | 9 | ||||
| -rw-r--r-- | elf/dl-lookup-direct.c | 116 | ||||
| -rw-r--r-- | elf/dl-open.c | 25 | ||||
| -rw-r--r-- | elf/libc-early-init.h | 35 | ||||
| -rw-r--r-- | elf/libc_early_init.c | 27 | ||||
| -rw-r--r-- | elf/rtld.c | 4 | ||||
| -rw-r--r-- | sysdeps/generic/ldsodefs.h | 17 | ||||
| -rw-r--r-- | sysdeps/mach/hurd/i386/init-first.c | 4 |
13 files changed, 283 insertions, 10 deletions
diff --git a/csu/init-first.c b/csu/init-first.c index 264e6f348d..d214af7116 100644 --- a/csu/init-first.c +++ b/csu/init-first.c @@ -16,7 +16,6 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ -#include <ctype.h> #include <stdio.h> #include <stdlib.h> #include <fcntl.h> @@ -75,9 +74,6 @@ _init_first (int argc, char **argv, char **envp) __init_misc (argc, argv, envp); - /* Initialize ctype data. */ - __ctype_init (); - #if defined SHARED && !defined NO_CTORS_DTORS_SECTIONS __libc_global_ctors (); #endif diff --git a/csu/libc-start.c b/csu/libc-start.c index 12468c5a89..ccc743c9d1 100644 --- a/csu/libc-start.c +++ b/csu/libc-start.c @@ -22,6 +22,7 @@ #include <ldsodefs.h> #include <exit-thread.h> #include <libc-internal.h> +#include <elf/libc-early-init.h> #include <elf/dl-tunables.h> @@ -238,6 +239,10 @@ LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL), __cxa_atexit ((void (*) (void *)) rtld_fini, NULL, NULL); #ifndef SHARED + /* Perform early initialization. In the shared case, this function + is called from the dynamic loader as early as possible. */ + __libc_early_init (); + /* Call the initializer of the libc. This is only needed here if we are compiling for the static library in which case we haven't run the constructors in `_dl_start_user'. */ diff --git a/elf/Makefile b/elf/Makefile index 6919e53c14..77da61ae64 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -25,7 +25,7 @@ headers = elf.h bits/elfclass.h link.h bits/link.h routines = $(all-dl-routines) dl-support dl-iteratephdr \ dl-addr dl-addr-obj enbl-secure dl-profstub \ dl-origin dl-libc dl-sym dl-sysdep dl-error \ - dl-reloc-static-pie + dl-reloc-static-pie libc_early_init # The core dynamic linking functions are in libc for the static and # profiled libraries. @@ -33,7 +33,8 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps hwcaps \ runtime init fini debug misc \ version profile tls origin scope \ execstack open close trampoline \ - exception sort-maps) + exception sort-maps lookup-direct \ + call-libc-early-init) ifeq (yes,$(use-ldconfig)) dl-routines += dl-cache endif diff --git a/elf/Versions b/elf/Versions index 705489fc51..3be879c4ad 100644 --- a/elf/Versions +++ b/elf/Versions @@ -26,6 +26,7 @@ libc { _dl_open_hook; _dl_open_hook2; _dl_sym; _dl_vsym; __libc_dlclose; __libc_dlopen_mode; __libc_dlsym; __libc_dlvsym; + __libc_early_init; # Internal error handling support. Interposes the functions in ld.so. _dl_signal_exception; _dl_catch_exception; diff --git a/elf/dl-call-libc-early-init.c b/elf/dl-call-libc-early-init.c new file mode 100644 index 0000000000..41e9ad9aad --- /dev/null +++ b/elf/dl-call-libc-early-init.c @@ -0,0 +1,41 @@ +/* Invoke the early initialization function in libc.so. + Copyright (C) 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/>. */ + +#include <assert.h> +#include <ldsodefs.h> +#include <libc-early-init.h> +#include <link.h> +#include <stddef.h> + +void +_dl_call_libc_early_init (struct link_map *libc_map) +{ + /* There is nothing to do if we did not actually load libc.so. */ + if (libc_map == NULL) + return; + + const ElfW(Sym) *sym + = _dl_lookup_direct (libc_map, "__libc_early_init", + 0x069682ac, /* dl_new_hash output. */ + "GLIBC_PRIVATE", + 0x0963cf85); /* _dl_elf_hash output. */ + assert (sym != NULL); + __typeof (__libc_early_init) *early_init + = DL_SYMBOL_ADDRESS (libc_map, sym); + early_init (); +} diff --git a/elf/dl-load.c b/elf/dl-load.c index a6b80f9395..06f2ba7264 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -30,6 +30,7 @@ #include <sys/param.h> #include <sys/stat.h> #include <sys/types.h> +#include <gnu/lib-names.h> /* Type for the buffer we put the ELF header and hopefully the program header. This buffer does not really have to be too large. In most @@ -1374,6 +1375,14 @@ cannot enable executable stack as shared object requires"); add_name_to_object (l, ((const char *) D_PTR (l, l_info[DT_STRTAB]) + l->l_info[DT_SONAME]->d_un.d_val)); + /* If we have newly loaded libc.so, update the namespace + description. */ + if (GL(dl_ns)[nsid].libc_map == NULL + && l->l_info[DT_SONAME] != NULL + && strcmp (((const char *) D_PTR (l, l_info[DT_STRTAB]) + + l->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0) + GL(dl_ns)[nsid].libc_map = l; + /* _dl_close can only eventually undo the module ID assignment (via remove_slotinfo) if this function returns a pointer to a link map. Therefore, delay this step until all possibilities for diff --git a/elf/dl-lookup-direct.c b/elf/dl-lookup-direct.c new file mode 100644 index 0000000000..5637ae89de --- /dev/null +++ b/elf/dl-lookup-direct.c @@ -0,0 +1,116 @@ +/* Look up a symbol in a single specified object. + 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/>. */ + +#include <ldsodefs.h> +#include <string.h> +#include <elf_machine_sym_no_match.h> +#include <dl-hash.h> + +/* This function corresponds to do_lookup_x in elf/dl-lookup.c. The + variant here is simplified because it requires symbol + versioning. */ +static const ElfW(Sym) * +check_match (const struct link_map *const map, const char *const undef_name, + const char *version, uint32_t version_hash, + const Elf_Symndx symidx) +{ + const ElfW(Sym) *symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); + const ElfW(Sym) *sym = &symtab[symidx]; + + unsigned int stt = ELFW(ST_TYPE) (sym->st_info); + if (__glibc_unlikely ((sym->st_value == 0 /* No value. */ + && sym->st_shndx != SHN_ABS + && stt != STT_TLS) + || elf_machine_sym_no_match (sym))) + return NULL; + + /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC, + STT_COMMON, STT_TLS, and STT_GNU_IFUNC since these are no + code/data definitions. */ +#define ALLOWED_STT \ + ((1 << STT_NOTYPE) | (1 << STT_OBJECT) | (1 << STT_FUNC) \ + | (1 << STT_COMMON) | (1 << STT_TLS) | (1 << STT_GNU_IFUNC)) + if (__glibc_unlikely (((1 << stt) & ALLOWED_STT) == 0)) + return NULL; + + const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); + + if (strcmp (strtab + sym->st_name, undef_name) != 0) + /* Not the symbol we are looking for. */ + return NULL; + + ElfW(Half) ndx = map->l_versyms[symidx] & 0x7fff; + if (map->l_versions[ndx].hash != version_hash + || strcmp (map->l_versions[ndx].name, version) != 0) + /* It's not the version we want. */ + return NULL; + + return sym; +} + + +/* This function corresponds to do_lookup_x in elf/dl-lookup.c. The + variant here is simplified because it does not search object + dependencies. It is optimized for a successful lookup. */ +const ElfW(Sym) * +_dl_lookup_direct (struct link_map *map, + const char *undef_name, uint32_t new_hash, + const char *version, uint32_t version_hash) +{ + const ElfW(Addr) *bitmask = map->l_gnu_bitmask; + if (__glibc_likely (bitmask != NULL)) + { + Elf32_Word bucket = map->l_gnu_buckets[new_hash % map->l_nbuckets]; + if (bucket != 0) + { + const Elf32_Word *hasharr = &map->l_gnu_chain_zero[bucket]; + + do + if (((*hasharr ^ new_hash) >> 1) == 0) + { + Elf_Symndx symidx = ELF_MACHINE_HASH_SYMIDX (map, hasharr); + const ElfW(Sym) *sym = check_match (map, undef_name, + version, version_hash, + symidx); + if (sym != NULL) + return sym; + } + while ((*hasharr++ & 1u) == 0); + } + } + else + { + /* Fallback code for lack of GNU_HASH support. */ + uint32_t old_hash = _dl_elf_hash (undef_name); + + /* Use the old SysV-style hash table. Search the appropriate + hash bucket in this object's symbol table for a definition + for the same symbol name. */ + for (Elf_Symndx symidx = map->l_buckets[old_hash % map->l_nbuckets]; + symidx != STN_UNDEF; + symidx = map->l_chain[symidx]) + { + const ElfW(Sym) *sym = check_match (map, undef_name, + version, version_hash, symidx); + if (sym != NULL) + return sym; + } + } + + return NULL; +} diff --git a/elf/dl-open.c b/elf/dl-open.c index 7b3b177aa6..ac7ab495e4 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -34,6 +34,7 @@ #include <atomic.h> #include <libc-internal.h> #include <array_length.h> +#include <libc-early-init.h> #include <dl-dst.h> #include <dl-prop.h> @@ -57,6 +58,13 @@ struct dl_open_args (non-negative). */ unsigned int original_global_scope_pending_adds; + /* Set to true by dl_open_worker if libc.so was already loaded into + the namespace at the time dl_open_worker was called. This is + used to determine whether libc.so early initialization has + already been done before, and whether to roll back the cached + libc_map value in the namespace in case of a dlopen failure. */ + bool libc_already_loaded; + /* Original parameters to the program and the current environment. */ int argc; char **argv; @@ -500,6 +508,11 @@ dl_open_worker (void *a) args->nsid = call_map->l_ns; } + /* The namespace ID is now known. Keep track of whether libc.so was + already loaded, to determine whether it is necessary to call the + early initialization routine (or clear libc_map on error). */ + args->libc_already_loaded = GL(dl_ns)[args->nsid].libc_map != NULL; + /* Retain the old value, so that it can be restored. */ args->original_global_scope_pending_adds = GL (dl_ns)[args->nsid]._ns_global_scope_pending_adds; @@ -734,6 +747,11 @@ dl_open_worker (void *a) if (relocation_in_progress) LIBC_PROBE (reloc_complete, 3, args->nsid, r, new); + /* If libc.so was not there before, attempt to call its early + initialization routine. */ + if (!args->libc_already_loaded) + _dl_call_libc_early_init (GL(dl_ns)[args->nsid].libc_map); + #ifndef SHARED DL_STATIC_INIT (new); #endif @@ -828,6 +846,8 @@ no more namespaces available for dlmopen()")); args.caller_dlopen = caller_dlopen; args.map = NULL; args.nsid = nsid; + /* args.libc_already_loaded is always assigned by dl_open_worker + (before any explicit/non-local returns). */ args.argc = argc; args.argv = argv; args.env = env; @@ -856,6 +876,11 @@ no more namespaces available for dlmopen()")); /* See if an error occurred during loading. */ if (__glibc_unlikely (exception.errstring != NULL)) { + /* Avoid keeping around a dangling reference to the libc.so link + map in case it has been cached in libc_map. */ + if (!args.libc_already_loaded) + GL(dl_ns)[nsid].libc_map = NULL; + /* Remove the object from memory. It may be in an inconsistent state if relocation failed, for example. */ if (args.map) diff --git a/elf/libc-early-init.h b/elf/libc-early-init.h new file mode 100644 index 0000000000..5185fa8895 --- /dev/null +++ b/elf/libc-early-init.h @@ -0,0 +1,35 @@ +/* Early initialization of libc.so. + Copyright (C) 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 _LIBC_EARLY_INIT_H +#define _LIBC_EARLY_INIT_H + +struct link_map; + +/* If LIBC_MAP is not NULL, look up the __libc_early_init symbol in it + and call this function. */ +void _dl_call_libc_early_init (struct link_map *libc_map) attribute_hidden; + +/* In the shared case, this function is defined in libc.so and invoked + from ld.so (or on the fist static dlopen) after complete relocation + of a new loaded libc.so, but before user-defined ELF constructors + run. In the static case, this function is called directly from the + startup code. */ +void __libc_early_init (void); + +#endif /* _LIBC_EARLY_INIT_H */ diff --git a/elf/libc_early_init.c b/elf/libc_early_init.c new file mode 100644 index 0000000000..7f4ca332b8 --- /dev/null +++ b/elf/libc_early_init.c @@ -0,0 +1,27 @@ +/* Early initialization of libc.so, libc.so side. + Copyright (C) 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/>. */ + +#include <ctype.h> +#include <libc-early-init.h> + +void +__libc_early_init (void) +{ + /* Initialize ctype data. */ + __ctype_init (); +} diff --git a/elf/rtld.c b/elf/rtld.c index b2ea21c98b..0016db86a7 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -46,6 +46,7 @@ #include <stackinfo.h> #include <not-cancel.h> #include <array_length.h> +#include <libc-early-init.h> #include <assert.h> @@ -2372,6 +2373,9 @@ ERROR: '%s': cannot process note segment.\n", _dl_argv[0]); rtld_timer_accum (&relocate_time, start); } + /* Relocation is complete. Perform early libc initialization. */ + _dl_call_libc_early_init (GL(dl_ns)[LM_ID_BASE].libc_map); + /* Do any necessary cleanups for the startup OS interface code. We do these now so that no calls are made after rtld re-relocation which might be resolved to different functions than we expect. diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 497938ffa2..5ff4a2831b 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -336,6 +336,10 @@ struct rtld_global recursive dlopen calls from ELF constructors. */ unsigned int _ns_global_scope_pending_adds; + /* Once libc.so has been loaded into the namespace, this points to + its link map. */ + struct link_map *libc_map; + /* Search table for unique objects. */ struct unique_sym_table { @@ -946,6 +950,19 @@ extern lookup_t _dl_lookup_symbol_x (const char *undef, attribute_hidden; +/* Restricted version of _dl_lookup_symbol_x. Searches MAP (and only + MAP) for the symbol UNDEF_NAME, with GNU hash NEW_HASH (computed + with dl_new_hash), symbol version VERSION, and symbol version hash + VERSION_HASH (computed with _dl_elf_hash). Returns a pointer to + the symbol table entry in MAP on success, or NULL on failure. MAP + must have symbol versioning information, or otherwise the result is + undefined. */ +const ElfW(Sym) *_dl_lookup_direct (struct link_map *map, + const char *undef_name, + uint32_t new_hash, + const char *version, + uint32_t version_hash) attribute_hidden; + /* Add the new link_map NEW to the end of the namespace list. */ extern void _dl_add_to_namespace_list (struct link_map *new, Lmid_t nsid) attribute_hidden; diff --git a/sysdeps/mach/hurd/i386/init-first.c b/sysdeps/mach/hurd/i386/init-first.c index 92bf45223f..a7dd4895d9 100644 --- a/sysdeps/mach/hurd/i386/init-first.c +++ b/sysdeps/mach/hurd/i386/init-first.c @@ -17,7 +17,6 @@ <https://www.gnu.org/licenses/>. */ #include <assert.h> -#include <ctype.h> #include <hurd.h> #include <stdio.h> #include <unistd.h> @@ -85,9 +84,6 @@ posixland_init (int argc, char **argv, char **envp) #endif __init_misc (argc, argv, envp); - /* Initialize ctype data. */ - __ctype_init (); - #if defined SHARED && !defined NO_CTORS_DTORS_SECTIONS __libc_global_ctors (); #endif |