Message ID | 68608ef426b88e73e0e3178497bcfe34dd8a66ef.1581182210.git.fweimer@redhat.com |
---|---|
State | New |
Headers | show |
Series | Avoid malloc symbol interposition in the dynamic loader [BZ #25486] | expand |
On 2/8/20 2:01 PM, Florian Weimer wrote: > The definitions are moved into a new file, elf/dl-sym-post.h, so that > this code can be used by the dynamic loader as well. OK for master. I like the cleanup. Reviewed-by: Carlos O'Donell <carlos@redhat.com> > --- > elf/dl-sym-post.h | 106 ++++++++++++++++++++++++++++++++++++++++++++++ > elf/dl-sym.c | 86 ++----------------------------------- > 2 files changed, 110 insertions(+), 82 deletions(-) > create mode 100644 elf/dl-sym-post.h > > diff --git a/elf/dl-sym-post.h b/elf/dl-sym-post.h > new file mode 100644 > index 0000000000..4c4f574633 > --- /dev/null > +++ b/elf/dl-sym-post.h > @@ -0,0 +1,106 @@ > +/* Post-processing of a symbol produced by dlsym, dlvsym. > + Copyright (C) 1999-2020 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/>. */ > + > + > +/* Return the link map containing the caller address. */ > +static struct link_map * > +_dl_sym_find_caller_link_map (ElfW(Addr) caller) > +{ > + struct link_map *l = _dl_find_dso_for_object (caller); > + if (l != NULL) > + return l; > + else > + /* If the address is not recognized the call comes from the main > + program (we hope). */ > + return GL(dl_ns)[LM_ID_BASE]._ns_loaded; > +} OK. > + > +/* Translates RESULT, *REF, VALUE into a symbol address from the point > + of view of MATCH. Performs IFUNC resolution and auditing if > + necessary. If MATCH is NULL, CALLER is used to determine it. */ > +static void * > +_dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value, > + ElfW(Addr) caller, struct link_map *match) > +{ > + /* Resolve indirect function address. */ > + if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC)) > + { > + DL_FIXUP_VALUE_TYPE fixup > + = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value); > + fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup)); > + value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup); > + } > + > +#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. */ > + if (__glibc_unlikely (GLRO(dl_naudit) > 0)) > + { > + const char *strtab = (const char *) D_PTR (result, > + l_info[DT_STRTAB]); > + /* Compute index of the symbol entry in the symbol table of > + the DSO with the definition. */ > + unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, > + l_info[DT_SYMTAB])); > + > + if (match == NULL) > + match = _dl_sym_find_caller_link_map (caller); > + > + if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) > + { > + unsigned int altvalue = 0; > + struct audit_ifaces *afct = GLRO(dl_audit); > + /* Synthesize a symbol record where the st_value field is > + the result. */ > + ElfW(Sym) sym = *ref; > + sym.st_value = (ElfW(Addr)) value; > + > + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) > + { > + struct auditstate *match_audit > + = link_map_audit_state (match, cnt); > + struct auditstate *result_audit > + = link_map_audit_state (result, cnt); > + if (afct->symbind != NULL > + && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0 > + || ((result_audit->bindflags & LA_FLG_BINDTO) > + != 0))) > + { > + unsigned int flags = altvalue | LA_SYMB_DLSYM; > + uintptr_t new_value > + = afct->symbind (&sym, ndx, > + &match_audit->cookie, > + &result_audit->cookie, > + &flags, strtab + ref->st_name); > + if (new_value != (uintptr_t) sym.st_value) > + { > + altvalue = LA_SYMB_ALTVALUE; > + sym.st_value = new_value; > + } > + } > + > + afct = afct->next; > + } > + > + value = (void *) sym.st_value; > + } > + } > +#endif > + return value; > +} OK. > diff --git a/elf/dl-sym.c b/elf/dl-sym.c > index b43a50e544..361b926ea9 100644 > --- a/elf/dl-sym.c > +++ b/elf/dl-sym.c > @@ -28,6 +28,7 @@ > #include <sysdep-cancel.h> > #include <dl-tls.h> > #include <dl-irel.h> > +#include <dl-sym-post.h> > > > #ifdef SHARED > @@ -80,19 +81,6 @@ call_dl_lookup (void *ptr) > args->flags, NULL); > } > > -/* Return the link map containing the caller address. */ > -static inline struct link_map * > -find_caller_link_map (ElfW(Addr) caller) > -{ > - struct link_map *l = _dl_find_dso_for_object (caller); > - if (l != NULL) > - return l; > - else > - /* If the address is not recognized the call comes from the main > - program (we hope). */ > - return GL(dl_ns)[LM_ID_BASE]._ns_loaded; > -} > - > static void * > do_sym (void *handle, const char *name, void *who, > struct r_found_version *vers, int flags) > @@ -106,7 +94,7 @@ do_sym (void *handle, const char *name, void *who, > > if (handle == RTLD_DEFAULT) > { > - match = find_caller_link_map (caller); > + match = _dl_sym_find_caller_link_map (caller); > > /* Search the global scope. We have the simple case where > we look up in the scope of an object which was part of > @@ -140,7 +128,7 @@ do_sym (void *handle, const char *name, void *who, > } > else if (handle == RTLD_NEXT) > { > - match = find_caller_link_map (caller); > + match = _dl_sym_find_caller_link_map (caller); > > if (__glibc_unlikely (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded)) > { > @@ -179,73 +167,7 @@ RTLD_NEXT used in code not dynamically loaded")); > #endif > value = DL_SYMBOL_ADDRESS (result, ref); > > - /* Resolve indirect function address. */ > - if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC)) > - { > - DL_FIXUP_VALUE_TYPE fixup > - = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value); > - fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup)); > - value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup); > - } > - > -#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. */ > - if (__glibc_unlikely (GLRO(dl_naudit) > 0)) > - { > - const char *strtab = (const char *) D_PTR (result, > - l_info[DT_STRTAB]); > - /* Compute index of the symbol entry in the symbol table of > - the DSO with the definition. */ > - unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, > - l_info[DT_SYMTAB])); > - > - if (match == NULL) > - match = find_caller_link_map (caller); > - > - if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) > - { > - unsigned int altvalue = 0; > - struct audit_ifaces *afct = GLRO(dl_audit); > - /* Synthesize a symbol record where the st_value field is > - the result. */ > - ElfW(Sym) sym = *ref; > - sym.st_value = (ElfW(Addr)) value; > - > - for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) > - { > - struct auditstate *match_audit > - = link_map_audit_state (match, cnt); > - struct auditstate *result_audit > - = link_map_audit_state (result, cnt); > - if (afct->symbind != NULL > - && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0 > - || ((result_audit->bindflags & LA_FLG_BINDTO) > - != 0))) > - { > - unsigned int flags = altvalue | LA_SYMB_DLSYM; > - uintptr_t new_value > - = afct->symbind (&sym, ndx, > - &match_audit->cookie, > - &result_audit->cookie, > - &flags, strtab + ref->st_name); > - if (new_value != (uintptr_t) sym.st_value) > - { > - altvalue = LA_SYMB_ALTVALUE; > - sym.st_value = new_value; > - } > - } > - > - afct = afct->next; > - } > - > - value = (void *) sym.st_value; > - } > - } > -#endif > - > - return value; > + return _dl_sym_post (result, ref, value, caller, match); > } > > return NULL; >
diff --git a/elf/dl-sym-post.h b/elf/dl-sym-post.h new file mode 100644 index 0000000000..4c4f574633 --- /dev/null +++ b/elf/dl-sym-post.h @@ -0,0 +1,106 @@ +/* Post-processing of a symbol produced by dlsym, dlvsym. + Copyright (C) 1999-2020 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/>. */ + + +/* Return the link map containing the caller address. */ +static struct link_map * +_dl_sym_find_caller_link_map (ElfW(Addr) caller) +{ + struct link_map *l = _dl_find_dso_for_object (caller); + if (l != NULL) + return l; + else + /* If the address is not recognized the call comes from the main + program (we hope). */ + return GL(dl_ns)[LM_ID_BASE]._ns_loaded; +} + +/* Translates RESULT, *REF, VALUE into a symbol address from the point + of view of MATCH. Performs IFUNC resolution and auditing if + necessary. If MATCH is NULL, CALLER is used to determine it. */ +static void * +_dl_sym_post (lookup_t result, const ElfW(Sym) *ref, void *value, + ElfW(Addr) caller, struct link_map *match) +{ + /* Resolve indirect function address. */ + if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC)) + { + DL_FIXUP_VALUE_TYPE fixup + = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value); + fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup)); + value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup); + } + +#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. */ + if (__glibc_unlikely (GLRO(dl_naudit) > 0)) + { + const char *strtab = (const char *) D_PTR (result, + l_info[DT_STRTAB]); + /* Compute index of the symbol entry in the symbol table of + the DSO with the definition. */ + unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, + l_info[DT_SYMTAB])); + + if (match == NULL) + match = _dl_sym_find_caller_link_map (caller); + + if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) + { + unsigned int altvalue = 0; + struct audit_ifaces *afct = GLRO(dl_audit); + /* Synthesize a symbol record where the st_value field is + the result. */ + ElfW(Sym) sym = *ref; + sym.st_value = (ElfW(Addr)) value; + + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + struct auditstate *match_audit + = link_map_audit_state (match, cnt); + struct auditstate *result_audit + = link_map_audit_state (result, cnt); + if (afct->symbind != NULL + && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0 + || ((result_audit->bindflags & LA_FLG_BINDTO) + != 0))) + { + unsigned int flags = altvalue | LA_SYMB_DLSYM; + uintptr_t new_value + = afct->symbind (&sym, ndx, + &match_audit->cookie, + &result_audit->cookie, + &flags, strtab + ref->st_name); + if (new_value != (uintptr_t) sym.st_value) + { + altvalue = LA_SYMB_ALTVALUE; + sym.st_value = new_value; + } + } + + afct = afct->next; + } + + value = (void *) sym.st_value; + } + } +#endif + return value; +} diff --git a/elf/dl-sym.c b/elf/dl-sym.c index b43a50e544..361b926ea9 100644 --- a/elf/dl-sym.c +++ b/elf/dl-sym.c @@ -28,6 +28,7 @@ #include <sysdep-cancel.h> #include <dl-tls.h> #include <dl-irel.h> +#include <dl-sym-post.h> #ifdef SHARED @@ -80,19 +81,6 @@ call_dl_lookup (void *ptr) args->flags, NULL); } -/* Return the link map containing the caller address. */ -static inline struct link_map * -find_caller_link_map (ElfW(Addr) caller) -{ - struct link_map *l = _dl_find_dso_for_object (caller); - if (l != NULL) - return l; - else - /* If the address is not recognized the call comes from the main - program (we hope). */ - return GL(dl_ns)[LM_ID_BASE]._ns_loaded; -} - static void * do_sym (void *handle, const char *name, void *who, struct r_found_version *vers, int flags) @@ -106,7 +94,7 @@ do_sym (void *handle, const char *name, void *who, if (handle == RTLD_DEFAULT) { - match = find_caller_link_map (caller); + match = _dl_sym_find_caller_link_map (caller); /* Search the global scope. We have the simple case where we look up in the scope of an object which was part of @@ -140,7 +128,7 @@ do_sym (void *handle, const char *name, void *who, } else if (handle == RTLD_NEXT) { - match = find_caller_link_map (caller); + match = _dl_sym_find_caller_link_map (caller); if (__glibc_unlikely (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded)) { @@ -179,73 +167,7 @@ RTLD_NEXT used in code not dynamically loaded")); #endif value = DL_SYMBOL_ADDRESS (result, ref); - /* Resolve indirect function address. */ - if (__glibc_unlikely (ELFW(ST_TYPE) (ref->st_info) == STT_GNU_IFUNC)) - { - DL_FIXUP_VALUE_TYPE fixup - = DL_FIXUP_MAKE_VALUE (result, (ElfW(Addr)) value); - fixup = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (fixup)); - value = (void *) DL_FIXUP_VALUE_CODE_ADDR (fixup); - } - -#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. */ - if (__glibc_unlikely (GLRO(dl_naudit) > 0)) - { - const char *strtab = (const char *) D_PTR (result, - l_info[DT_STRTAB]); - /* Compute index of the symbol entry in the symbol table of - the DSO with the definition. */ - unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, - l_info[DT_SYMTAB])); - - if (match == NULL) - match = find_caller_link_map (caller); - - if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) - { - unsigned int altvalue = 0; - struct audit_ifaces *afct = GLRO(dl_audit); - /* Synthesize a symbol record where the st_value field is - the result. */ - ElfW(Sym) sym = *ref; - sym.st_value = (ElfW(Addr)) value; - - for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) - { - struct auditstate *match_audit - = link_map_audit_state (match, cnt); - struct auditstate *result_audit - = link_map_audit_state (result, cnt); - if (afct->symbind != NULL - && ((match_audit->bindflags & LA_FLG_BINDFROM) != 0 - || ((result_audit->bindflags & LA_FLG_BINDTO) - != 0))) - { - unsigned int flags = altvalue | LA_SYMB_DLSYM; - uintptr_t new_value - = afct->symbind (&sym, ndx, - &match_audit->cookie, - &result_audit->cookie, - &flags, strtab + ref->st_name); - if (new_value != (uintptr_t) sym.st_value) - { - altvalue = LA_SYMB_ALTVALUE; - sym.st_value = new_value; - } - } - - afct = afct->next; - } - - value = (void *) sym.st_value; - } - } -#endif - - return value; + return _dl_sym_post (result, ref, value, caller, match); } return NULL;