diff --git a/NEWS b/NEWS index 9294a7b953..ed8ac0d0df 100644 --- a/NEWS +++ b/NEWS @@ -230,6 +230,9 @@ Major new features: execute programs that do not have any dynamic dependency (that is, they are statically linked). This feature is Linux-specific. +* The audit libraries will avoid unnecessary slowdown if it is not required + PLT tracking (by not implementing the la_pltenter or la_pltexit callbacks). + Deprecated and removed features, and other changes affecting compatibility: * The function pthread_mutex_consistent_np has been deprecated; programs diff --git a/elf/Makefile b/elf/Makefile index 5e4ffeb530..6368b6a112 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -231,13 +231,15 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \ tst-tls20 tst-tls21 tst-dlmopen-dlerror tst-dlmopen-gethostbyname \ tst-dl-is_dso tst-ro-dynamic \ tst-audit18 \ + tst-audit19b \ tst-rtld-run-static \ # reldep9 tests-internal += loadtest unload unload2 circleload1 \ neededtest neededtest2 neededtest3 neededtest4 \ tst-tls3 tst-tls6 tst-tls7 tst-tls8 tst-dlmopen2 \ tst-ptrguard1 tst-stackguard1 \ - tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split + tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split \ + tst-audit19a tests-container += tst-pldd tst-dlopen-tlsmodid-container \ tst-dlopen-self-container tst-preload-pthread-libc test-srcs = tst-pathopt @@ -377,6 +379,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \ tst-dlmopen-gethostbyname-mod tst-ro-dynamic-mod \ tst-auditmod18 \ tst-audit18mod \ + tst-auditmod19a \ + tst-auditmod19b \ + tst-audit19bmod \ # Most modules build with _ISOMAC defined, but those filtered out # depend on internal headers. @@ -1566,6 +1571,13 @@ $(objpfx)tst-audit18.out: $(objpfx)tst-auditmod18.so \ $(objpfx)tst-audit18mod.so tst-audit18-ARGS = -- $(host-test-program-cmd) +$(objpfx)tst-audit19a.out: $(objpfx)tst-auditmod19a.so +tst-audit19a-ENV = LD_AUDIT=$(objpfx)tst-auditmod19a.so + +$(objpfx)tst-audit19b.out: $(objpfx)tst-auditmod19b.so +$(objpfx)tst-audit19b: $(objpfx)tst-audit19bmod.so +tst-audit19b-ARGS = -- $(host-test-program-cmd) + # tst-sonamemove links against an older implementation of the library. LDFLAGS-tst-sonamemove-linkmod1.so = \ -Wl,--version-script=tst-sonamemove-linkmod1.map \ diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c index 0d5b727c64..98a24b3b9d 100644 --- a/elf/dl-reloc.c +++ b/elf/dl-reloc.c @@ -205,12 +205,28 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[], int skip_ifunc = reloc_mode & __RTLD_NOIFUNC; #ifdef SHARED + bool consider_symbind = false; /* If we are auditing, install the same handlers we need for profiling. */ if ((reloc_mode & __RTLD_AUDIT) == 0) - consider_profiling |= GLRO(dl_audit) != NULL; + { + struct audit_ifaces *afct = GLRO(dl_audit); + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + /* Profiling is needed only if PLT hooks are provided. */ + if (afct->ARCH_LA_PLTENTER != NULL + || afct->ARCH_LA_PLTEXIT != NULL) + consider_profiling = 1; + if (afct->symbind != NULL) + consider_symbind = true; + + afct = afct->next; + } + } #elif defined PROF /* Never use dynamic linker profiling for gprof profiling code. */ # define consider_profiling 0 +#else +# define consider_symbind 0 #endif if (l->l_relocated) @@ -272,7 +288,7 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[], ELF_DYNAMIC_RELOCATE (l, scope, lazy, consider_profiling, skip_ifunc); #ifndef PROF - if (__glibc_unlikely (consider_profiling) + if ((consider_profiling || consider_symbind) && l->l_info[DT_PLTRELSZ] != NULL) { /* Allocate the array which will contain the already found diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c index e42f6e8b8d..77a5cccdcb 100644 --- a/elf/dl-runtime.c +++ b/elf/dl-runtime.c @@ -124,6 +124,37 @@ _dl_fixup ( && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)) value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value)); +#ifdef SHARED + /* Auditing checkpoint: we have a new binding. Provide the auditing + libraries the possibility to change the value and tell us whether further + auditing is wanted. + The l_reloc_result is only allocated if there is an audit module which + provides a la_symbind. */ + if (l->l_reloc_result != NULL) + { + /* This is the address in the array where we store the result of previous + relocations. */ + struct reloc_result *reloc_result + = &l->l_reloc_result[reloc_index (pltgot, reloc_arg, sizeof (PLTREL))]; + unsigned int init = atomic_load_acquire (&reloc_result->init); + if (init == 0) + { + _dl_audit_symbind (l, reloc_result, sym, &value, result); + + /* Store the result for later runs. */ + if (__glibc_likely (! GLRO(dl_bind_not))) + { + reloc_result->addr = value; + /* Guarantee all previous writes complete before init is + updated. See CONCURRENCY NOTES below. */ + atomic_store_release (&reloc_result->init, 1); + } + } + else + value = reloc_result->addr; + } +#endif + /* Finally, fix up the plt itself. */ if (__glibc_unlikely (GLRO(dl_bind_not))) return value; diff --git a/elf/rtld.c b/elf/rtld.c index 4952170621..b215ce6909 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -1017,13 +1017,7 @@ ERROR: audit interface '%s' requires version %d (maximum supported version %d); "la_objsearch\0" "la_objopen\0" "la_preinit\0" -#if __ELF_NATIVE_CLASS == 32 - "la_symbind32\0" -#elif __ELF_NATIVE_CLASS == 64 - "la_symbind64\0" -#else -# error "__ELF_NATIVE_CLASS must be defined" -#endif + LA_SYMBIND "\0" #define STRING(s) __STRING (s) "la_" STRING (ARCH_LA_PLTENTER) "\0" "la_" STRING (ARCH_LA_PLTEXIT) "\0" diff --git a/elf/tst-audit19a.c b/elf/tst-audit19a.c new file mode 100644 index 0000000000..035cde9351 --- /dev/null +++ b/elf/tst-audit19a.c @@ -0,0 +1,38 @@ +/* Check if DT_AUDIT a module without la_plt{enter,exit} symbols does not incur + in profiling (BZ#15533). + Copyright (C) 2021 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 + . */ + +#include +#include +#include + +static int +do_test (void) +{ + void *h = xdlopen ("tst-auditmod19a.so", RTLD_NOW); + + struct link_map *lmap; + TEST_VERIFY_EXIT (dlinfo (h, RTLD_DI_LINKMAP, &lmap) == 0); + + /* The internal array is only allocated if profiling is enabled. */ + TEST_VERIFY (lmap->l_reloc_result == NULL); + + return 0; +} + +#include diff --git a/elf/tst-audit19b.c b/elf/tst-audit19b.c new file mode 100644 index 0000000000..da015734f2 --- /dev/null +++ b/elf/tst-audit19b.c @@ -0,0 +1,94 @@ +/* Check if DT_AUDIT a module with la_plt{enter,exit} call la_symbind + for lazy resolution. + Copyright (C) 2021 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 + . */ + +#include +#include +#include +#include +#include +#include +#include + +static int restart; +#define CMDLINE_OPTIONS \ + { "restart", no_argument, &restart, 1 }, + +int tst_audit18bmod1_func (void); + +static int +handle_restart (void) +{ + TEST_COMPARE (tst_audit18bmod1_func (), 10); + return 0; +} + +static inline bool +startswith (const char *str, const char *pre) +{ + size_t lenpre = strlen (pre); + size_t lenstr = strlen (str); + return lenstr < lenpre ? false : memcmp (pre, str, lenpre) == 0; +} + +static int +do_test (int argc, char *argv[]) +{ + /* We must have either: + - One our fource parameters left if called initially: + + path to ld.so optional + + "--library-path" optional + + the library path optional + + the application name */ + + if (restart) + return handle_restart (); + + char *spargv[9]; + int i = 0; + for (; i < argc - 1; i++) + spargv[i] = argv[i + 1]; + spargv[i++] = (char *) "--direct"; + spargv[i++] = (char *) "--restart"; + spargv[i] = NULL; + + setenv ("LD_AUDIT", "tst-auditmod18b.so", 0); + struct support_capture_subprocess result + = support_capture_subprogram (spargv[0], spargv); + support_capture_subprocess_check (&result, "tst-audit18b", 0, sc_allow_stderr); + + bool find_symbind = false; + + FILE *out = fmemopen (result.err.buffer, result.err.length, "r"); + TEST_VERIFY (out != NULL); + char *buffer = NULL; + size_t buffer_length = 0; + while (xgetline (&buffer, &buffer_length, out)) + if (startswith (buffer, "la_symbind: tst_audit18bmod1_func") == 0) + find_symbind = true; + + TEST_COMPARE (find_symbind, true); + + free (buffer); + xfclose (out); + + return 0; +} + +#define TEST_FUNCTION_ARGV do_test +#include diff --git a/elf/tst-audit19bmod.c b/elf/tst-audit19bmod.c new file mode 100644 index 0000000000..9ffdcd8f3f --- /dev/null +++ b/elf/tst-audit19bmod.c @@ -0,0 +1,23 @@ +/* Extra module for tst-audit18b. + Copyright (C) 2021 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 + . */ + +int +tst_audit18bmod1_func (void) +{ + return 10; +} diff --git a/elf/tst-auditmod19a.c b/elf/tst-auditmod19a.c new file mode 100644 index 0000000000..f582040994 --- /dev/null +++ b/elf/tst-auditmod19a.c @@ -0,0 +1,25 @@ +/* Audit module for tst-audit18a. + Copyright (C) 2021 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 + . */ + +#include + +unsigned int +la_version (unsigned int version) +{ + return LAV_CURRENT; +} diff --git a/elf/tst-auditmod19b.c b/elf/tst-auditmod19b.c new file mode 100644 index 0000000000..e2248b2a75 --- /dev/null +++ b/elf/tst-auditmod19b.c @@ -0,0 +1,46 @@ +/* Audit module for tst-audit18b. + Copyright (C) 2021 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 + . */ + +#include +#include +#include + +unsigned int +la_version (unsigned int version) +{ + return LAV_CURRENT; +} + +unsigned int +la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie) +{ + return LA_FLG_BINDTO | LA_FLG_BINDFROM; +} + +uintptr_t +#if __ELF_NATIVE_CLASS == 32 +la_symbind32 (Elf32_Sym *sym, unsigned int ndx, uintptr_t *refcook, + uintptr_t *defcook, unsigned int *flags, const char *symname) +#else +la_symbind64 (Elf64_Sym *sym, unsigned int ndx, uintptr_t *refcook, + uintptr_t *defcook, unsigned int *flags, const char *symname) +#endif +{ + fprintf (stderr, "la_symbind: %s\n", symname); + return sym->st_value; +} diff --git a/include/link.h b/include/link.h index c1c382ccfa..6a9f788d2b 100644 --- a/include/link.h +++ b/include/link.h @@ -367,8 +367,10 @@ extern struct r_debug_extended _r_debug_extended attribute_hidden; #if __ELF_NATIVE_CLASS == 32 # define symbind symbind32 +# define LA_SYMBIND "la_symbind32" #elif __ELF_NATIVE_CLASS == 64 # define symbind symbind64 +# define LA_SYMBIND "la_symbind64" #else # error "__ELF_NATIVE_CLASS must be defined" #endif