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Diffstat (limited to 'REORG.TODO/elf/dl-runtime.c')
| -rw-r--r-- | REORG.TODO/elf/dl-runtime.c | 480 |
1 files changed, 480 insertions, 0 deletions
diff --git a/REORG.TODO/elf/dl-runtime.c b/REORG.TODO/elf/dl-runtime.c new file mode 100644 index 0000000000..7d1d240403 --- /dev/null +++ b/REORG.TODO/elf/dl-runtime.c @@ -0,0 +1,480 @@ +/* On-demand PLT fixup for shared objects. + Copyright (C) 1995-2017 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 + <http://www.gnu.org/licenses/>. */ + +#define IN_DL_RUNTIME 1 /* This can be tested in dl-machine.h. */ + +#include <alloca.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/param.h> +#include <ldsodefs.h> +#include <sysdep-cancel.h> +#include "dynamic-link.h" +#include <tls.h> +#include <dl-irel.h> + + +#if (!ELF_MACHINE_NO_RELA && !defined ELF_MACHINE_PLT_REL) \ + || ELF_MACHINE_NO_REL +# define PLTREL ElfW(Rela) +#else +# define PLTREL ElfW(Rel) +#endif + +/* The fixup functions might have need special attributes. If none + are provided define the macro as empty. */ +#ifndef ARCH_FIXUP_ATTRIBUTE +# define ARCH_FIXUP_ATTRIBUTE +#endif + +#ifndef reloc_offset +# define reloc_offset reloc_arg +# define reloc_index reloc_arg / sizeof (PLTREL) +#endif + + + +/* This function is called through a special trampoline from the PLT the + first time each PLT entry is called. We must perform the relocation + specified in the PLT of the given shared object, and return the resolved + function address to the trampoline, which will restart the original call + to that address. Future calls will bounce directly from the PLT to the + function. */ + +DL_FIXUP_VALUE_TYPE +attribute_hidden __attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE +_dl_fixup ( +# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS + ELF_MACHINE_RUNTIME_FIXUP_ARGS, +# endif + struct link_map *l, ElfW(Word) reloc_arg) +{ + const ElfW(Sym) *const symtab + = (const void *) D_PTR (l, l_info[DT_SYMTAB]); + const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]); + + const PLTREL *const reloc + = (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset); + const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)]; + void *const rel_addr = (void *)(l->l_addr + reloc->r_offset); + lookup_t result; + DL_FIXUP_VALUE_TYPE value; + + /* Sanity check that we're really looking at a PLT relocation. */ + assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT); + + /* Look up the target symbol. If the normal lookup rules are not + used don't look in the global scope. */ + if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0) + { + const struct r_found_version *version = NULL; + + if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) + { + const ElfW(Half) *vernum = + (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]); + ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff; + version = &l->l_versions[ndx]; + if (version->hash == 0) + version = NULL; + } + + /* We need to keep the scope around so do some locking. This is + not necessary for objects which cannot be unloaded or when + we are not using any threads (yet). */ + int flags = DL_LOOKUP_ADD_DEPENDENCY; + if (!RTLD_SINGLE_THREAD_P) + { + THREAD_GSCOPE_SET_FLAG (); + flags |= DL_LOOKUP_GSCOPE_LOCK; + } + +#ifdef RTLD_ENABLE_FOREIGN_CALL + RTLD_ENABLE_FOREIGN_CALL; +#endif + + result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, l->l_scope, + version, ELF_RTYPE_CLASS_PLT, flags, NULL); + + /* We are done with the global scope. */ + if (!RTLD_SINGLE_THREAD_P) + THREAD_GSCOPE_RESET_FLAG (); + +#ifdef RTLD_FINALIZE_FOREIGN_CALL + RTLD_FINALIZE_FOREIGN_CALL; +#endif + + /* Currently result contains the base load address (or link map) + of the object that defines sym. Now add in the symbol + offset. */ + value = DL_FIXUP_MAKE_VALUE (result, + sym ? (LOOKUP_VALUE_ADDRESS (result) + + sym->st_value) : 0); + } + else + { + /* We already found the symbol. The module (and therefore its load + address) is also known. */ + value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + sym->st_value); + result = l; + } + + /* And now perhaps the relocation addend. */ + value = elf_machine_plt_value (l, reloc, value); + + if (sym != NULL + && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)) + value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value)); + + /* Finally, fix up the plt itself. */ + if (__glibc_unlikely (GLRO(dl_bind_not))) + return value; + + return elf_machine_fixup_plt (l, result, reloc, rel_addr, value); +} + +#ifndef PROF +DL_FIXUP_VALUE_TYPE +__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE +_dl_profile_fixup ( +#ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS + ELF_MACHINE_RUNTIME_FIXUP_ARGS, +#endif + struct link_map *l, ElfW(Word) reloc_arg, + ElfW(Addr) retaddr, void *regs, long int *framesizep) +{ + void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = _dl_mcount; + + if (l->l_reloc_result == NULL) + { + /* BZ #14843: ELF_DYNAMIC_RELOCATE is called before l_reloc_result + is allocated. We will get here if ELF_DYNAMIC_RELOCATE calls a + resolver function to resolve an IRELATIVE relocation and that + resolver calls a function that is not yet resolved (lazy). For + example, the resolver in x86-64 libm.so calls __get_cpu_features + defined in libc.so. Skip audit and resolve the external function + in this case. */ + *framesizep = -1; + return _dl_fixup ( +# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS +# ifndef ELF_MACHINE_RUNTIME_FIXUP_PARAMS +# error Please define ELF_MACHINE_RUNTIME_FIXUP_PARAMS. +# endif + ELF_MACHINE_RUNTIME_FIXUP_PARAMS, +# endif + l, reloc_arg); + } + + /* 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]; + DL_FIXUP_VALUE_TYPE *resultp = &reloc_result->addr; + + DL_FIXUP_VALUE_TYPE value = *resultp; + if (DL_FIXUP_VALUE_CODE_ADDR (value) == 0) + { + /* This is the first time we have to relocate this object. */ + const ElfW(Sym) *const symtab + = (const void *) D_PTR (l, l_info[DT_SYMTAB]); + const char *strtab = (const char *) D_PTR (l, l_info[DT_STRTAB]); + + const PLTREL *const reloc + = (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset); + const ElfW(Sym) *refsym = &symtab[ELFW(R_SYM) (reloc->r_info)]; + const ElfW(Sym) *defsym = refsym; + lookup_t result; + + /* Sanity check that we're really looking at a PLT relocation. */ + assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT); + + /* Look up the target symbol. If the symbol is marked STV_PROTECTED + don't look in the global scope. */ + if (__builtin_expect (ELFW(ST_VISIBILITY) (refsym->st_other), 0) == 0) + { + const struct r_found_version *version = NULL; + + if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) + { + const ElfW(Half) *vernum = + (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]); + ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff; + version = &l->l_versions[ndx]; + if (version->hash == 0) + version = NULL; + } + + /* We need to keep the scope around so do some locking. This is + not necessary for objects which cannot be unloaded or when + we are not using any threads (yet). */ + int flags = DL_LOOKUP_ADD_DEPENDENCY; + if (!RTLD_SINGLE_THREAD_P) + { + THREAD_GSCOPE_SET_FLAG (); + flags |= DL_LOOKUP_GSCOPE_LOCK; + } + + result = _dl_lookup_symbol_x (strtab + refsym->st_name, l, + &defsym, l->l_scope, version, + ELF_RTYPE_CLASS_PLT, flags, NULL); + + /* We are done with the global scope. */ + if (!RTLD_SINGLE_THREAD_P) + THREAD_GSCOPE_RESET_FLAG (); + + /* Currently result contains the base load address (or link map) + of the object that defines sym. Now add in the symbol + offset. */ + value = DL_FIXUP_MAKE_VALUE (result, + defsym != NULL + ? LOOKUP_VALUE_ADDRESS (result) + + defsym->st_value : 0); + + if (defsym != NULL + && __builtin_expect (ELFW(ST_TYPE) (defsym->st_info) + == STT_GNU_IFUNC, 0)) + value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value)); + } + else + { + /* We already found the symbol. The module (and therefore its load + address) is also known. */ + value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + refsym->st_value); + + if (__builtin_expect (ELFW(ST_TYPE) (refsym->st_info) + == STT_GNU_IFUNC, 0)) + value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value)); + + result = l; + } + /* And now perhaps the relocation addend. */ + value = elf_machine_plt_value (l, reloc, 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. */ + if (defsym != NULL && GLRO(dl_naudit) > 0) + { + reloc_result->bound = result; + /* Compute index of the symbol entry in the symbol table of + the DSO with the definition. */ + reloc_result->boundndx = (defsym + - (ElfW(Sym) *) D_PTR (result, + l_info[DT_SYMTAB])); + + /* Determine whether any of the two participating DSOs is + interested in auditing. */ + if ((l->l_audit_any_plt | result->l_audit_any_plt) != 0) + { + unsigned int flags = 0; + struct audit_ifaces *afct = GLRO(dl_audit); + /* Synthesize a symbol record where the st_value field is + the result. */ + ElfW(Sym) sym = *defsym; + sym.st_value = DL_FIXUP_VALUE_ADDR (value); + + /* Keep track whether there is any interest in tracing + the call in the lower two bits. */ + assert (DL_NNS * 2 <= sizeof (reloc_result->flags) * 8); + assert ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) == 3); + reloc_result->enterexit = LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT; + + const char *strtab2 = (const void *) D_PTR (result, + l_info[DT_STRTAB]); + + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + /* XXX Check whether both DSOs must request action or + only one */ + if ((l->l_audit[cnt].bindflags & LA_FLG_BINDFROM) != 0 + && (result->l_audit[cnt].bindflags & LA_FLG_BINDTO) != 0) + { + if (afct->symbind != NULL) + { + uintptr_t new_value + = afct->symbind (&sym, reloc_result->boundndx, + &l->l_audit[cnt].cookie, + &result->l_audit[cnt].cookie, + &flags, + strtab2 + defsym->st_name); + if (new_value != (uintptr_t) sym.st_value) + { + flags |= LA_SYMB_ALTVALUE; + sym.st_value = new_value; + } + } + + /* Remember the results for every audit library and + store a summary in the first two bits. */ + reloc_result->enterexit + &= flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT); + reloc_result->enterexit + |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT)) + << ((cnt + 1) * 2)); + } + else + /* If the bind flags say this auditor is not interested, + set the bits manually. */ + reloc_result->enterexit + |= ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) + << ((cnt + 1) * 2)); + + afct = afct->next; + } + + reloc_result->flags = flags; + value = DL_FIXUP_ADDR_VALUE (sym.st_value); + } + else + /* Set all bits since this symbol binding is not interesting. */ + reloc_result->enterexit = (1u << DL_NNS) - 1; + } +#endif + + /* Store the result for later runs. */ + if (__glibc_likely (! GLRO(dl_bind_not))) + *resultp = value; + } + + /* By default we do not call the pltexit function. */ + long int framesize = -1; + +#ifdef SHARED + /* Auditing checkpoint: report the PLT entering and allow the + auditors to change the value. */ + if (DL_FIXUP_VALUE_CODE_ADDR (value) != 0 && GLRO(dl_naudit) > 0 + /* Don't do anything if no auditor wants to intercept this call. */ + && (reloc_result->enterexit & LA_SYMB_NOPLTENTER) == 0) + { + ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound, + l_info[DT_SYMTAB]) + + reloc_result->boundndx); + + /* Set up the sym parameter. */ + ElfW(Sym) sym = *defsym; + sym.st_value = DL_FIXUP_VALUE_ADDR (value); + + /* Get the symbol name. */ + const char *strtab = (const void *) D_PTR (reloc_result->bound, + l_info[DT_STRTAB]); + const char *symname = strtab + sym.st_name; + + /* Keep track of overwritten addresses. */ + unsigned int flags = reloc_result->flags; + + struct audit_ifaces *afct = GLRO(dl_audit); + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + if (afct->ARCH_LA_PLTENTER != NULL + && (reloc_result->enterexit + & (LA_SYMB_NOPLTENTER << (2 * (cnt + 1)))) == 0) + { + long int new_framesize = -1; + uintptr_t new_value + = afct->ARCH_LA_PLTENTER (&sym, reloc_result->boundndx, + &l->l_audit[cnt].cookie, + &reloc_result->bound->l_audit[cnt].cookie, + regs, &flags, symname, + &new_framesize); + if (new_value != (uintptr_t) sym.st_value) + { + flags |= LA_SYMB_ALTVALUE; + sym.st_value = new_value; + } + + /* Remember the results for every audit library and + store a summary in the first two bits. */ + reloc_result->enterexit + |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT)) + << (2 * (cnt + 1))); + + if ((reloc_result->enterexit & (LA_SYMB_NOPLTEXIT + << (2 * (cnt + 1)))) + == 0 && new_framesize != -1 && framesize != -2) + { + /* If this is the first call providing information, + use it. */ + if (framesize == -1) + framesize = new_framesize; + /* If two pltenter calls provide conflicting information, + use the larger value. */ + else if (new_framesize != framesize) + framesize = MAX (new_framesize, framesize); + } + } + + afct = afct->next; + } + + value = DL_FIXUP_ADDR_VALUE (sym.st_value); + } +#endif + + /* Store the frame size information. */ + *framesizep = framesize; + + (*mcount_fct) (retaddr, DL_FIXUP_VALUE_CODE_ADDR (value)); + + return value; +} + +#endif /* PROF */ + + +#include <stdio.h> +void +ARCH_FIXUP_ATTRIBUTE +_dl_call_pltexit (struct link_map *l, ElfW(Word) reloc_arg, + const void *inregs, void *outregs) +{ +#ifdef SHARED + /* This is the address in the array where we store the result of previous + relocations. */ + // XXX Maybe the bound information must be stored on the stack since + // XXX with bind_not a new value could have been stored in the meantime. + struct reloc_result *reloc_result = &l->l_reloc_result[reloc_index]; + ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound, + l_info[DT_SYMTAB]) + + reloc_result->boundndx); + + /* Set up the sym parameter. */ + ElfW(Sym) sym = *defsym; + sym.st_value = DL_FIXUP_VALUE_ADDR (reloc_result->addr); + + /* Get the symbol name. */ + const char *strtab = (const void *) D_PTR (reloc_result->bound, + l_info[DT_STRTAB]); + const char *symname = strtab + sym.st_name; + + struct audit_ifaces *afct = GLRO(dl_audit); + for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) + { + if (afct->ARCH_LA_PLTEXIT != NULL + && (reloc_result->enterexit + & (LA_SYMB_NOPLTEXIT >> (2 * cnt))) == 0) + { + afct->ARCH_LA_PLTEXIT (&sym, reloc_result->boundndx, + &l->l_audit[cnt].cookie, + &reloc_result->bound->l_audit[cnt].cookie, + inregs, outregs, symname); + } + + afct = afct->next; + } +#endif +} |