diff options
Diffstat (limited to 'elf/dl-runtime.c')
| -rw-r--r-- | elf/dl-runtime.c | 320 |
1 files changed, 268 insertions, 52 deletions
diff --git a/elf/dl-runtime.c b/elf/dl-runtime.c index a0aecda..ee2b8b5 100644 --- a/elf/dl-runtime.c +++ b/elf/dl-runtime.c @@ -1,5 +1,5 @@ /* On-demand PLT fixup for shared objects. - Copyright (C) 1995-2002, 2003, 2004 Free Software Foundation, Inc. + Copyright (C) 1995-2006, 2007 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 @@ -22,8 +22,12 @@ #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> + #if (!defined ELF_MACHINE_NO_RELA && !defined ELF_MACHINE_PLT_REL) \ || ELF_MACHINE_NO_REL @@ -51,15 +55,15 @@ function. */ #ifndef ELF_MACHINE_NO_PLT -static ElfW(Addr) -__attribute ((used, noinline)) ARCH_FIXUP_ATTRIBUTE -fixup ( +DL_FIXUP_VALUE_TYPE +__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE +_dl_fixup ( # ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS - ELF_MACHINE_RUNTIME_FIXUP_ARGS, + ELF_MACHINE_RUNTIME_FIXUP_ARGS, # endif - /* GKM FIXME: Fix trampoline to pass bounds so we can do - without the `__unbounded' qualifier. */ - struct link_map *__unbounded l, ElfW(Word) reloc_offset) + /* GKM FIXME: Fix trampoline to pass bounds so we can do + without the `__unbounded' qualifier. */ + struct link_map *__unbounded l, ElfW(Word) reloc_offset) { const ElfW(Sym) *const symtab = (const void *) D_PTR (l, l_info[DT_SYMTAB]); @@ -70,7 +74,7 @@ fixup ( 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; - ElfW(Addr) value; + 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); @@ -80,8 +84,6 @@ fixup ( if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0) { const struct r_found_version *version = NULL; - // XXX Why exactly do we have the differentiation of the flags here? - int flags = DL_LOOKUP_ADD_DEPENDENCY; if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) { @@ -91,27 +93,35 @@ fixup ( version = &l->l_versions[ndx]; if (version->hash == 0) version = NULL; - else - flags = 0; } - result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, - l->l_scope, version, ELF_RTYPE_CLASS_PLT, - DL_LOOKUP_ADD_DEPENDENCY, 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 (); + + 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 (); /* Currently result contains the base load address (or link map) of the object that defines sym. Now add in the symbol offset. */ - value = (sym ? LOOKUP_VALUE_ADDRESS (result) + sym->st_value : 0); + 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 = l->l_addr + sym->st_value; -#ifdef DL_LOOKUP_RETURNS_MAP + value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + sym->st_value); result = l; -#endif } /* And now perhaps the relocation addend. */ @@ -127,45 +137,45 @@ fixup ( #if !defined PROF && !defined ELF_MACHINE_NO_PLT && !__BOUNDED_POINTERS__ -static ElfW(Addr) -__attribute ((used, noinline)) ARCH_FIXUP_ATTRIBUTE -profile_fixup ( +DL_FIXUP_VALUE_TYPE +__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE +_dl_profile_fixup ( #ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS - ELF_MACHINE_RUNTIME_FIXUP_ARGS, + ELF_MACHINE_RUNTIME_FIXUP_ARGS, #endif - struct link_map *l, ElfW(Word) reloc_offset, ElfW(Addr) retaddr) + struct link_map *l, ElfW(Word) reloc_offset, + ElfW(Addr) retaddr, void *regs, long int *framesizep) { void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = INTUSE(_dl_mcount); - ElfW(Addr) *resultp; - lookup_t result; - ElfW(Addr) value; /* This is the address in the array where we store the result of previous relocations. */ - resultp = &l->l_reloc_result[reloc_offset / sizeof (PLTREL)]; + struct reloc_result *reloc_result + = &l->l_reloc_result[reloc_offset / sizeof (PLTREL)]; + DL_FIXUP_VALUE_TYPE *resultp = &reloc_result->addr; - value = *resultp; - if (value == 0) + 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 void *) D_PTR (l, l_info[DT_STRTAB]); + 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) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)]; + 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) (sym->st_other), 0) == 0) + if (__builtin_expect (ELFW(ST_VISIBILITY) (refsym->st_other), 0) == 0) { const struct r_found_version *version = NULL; - // XXX Why exactly do we have the differentiation of the flags here? - int flags = DL_LOOKUP_ADD_DEPENDENCY; if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) { @@ -175,38 +185,208 @@ profile_fixup ( version = &l->l_versions[ndx]; if (version->hash == 0) version = NULL; - else - flags = 0; } - result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, - l->l_scope, version, - ELF_RTYPE_CLASS_PLT, - DL_LOOKUP_ADD_DEPENDENCY, 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 (); + + 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 = (sym ? LOOKUP_VALUE_ADDRESS (result) + sym->st_value : 0); + value = DL_FIXUP_MAKE_VALUE (result, + defsym != NULL + ? LOOKUP_VALUE_ADDRESS (result) + + defsym->st_value : 0); } else { /* We already found the symbol. The module (and therefore its load address) is also known. */ - value = l->l_addr + sym->st_value; -#ifdef DL_LOOKUP_RETURNS_MAP + value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + refsym->st_value); result = l; -#endif } /* 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 altvalue = 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) + { + unsigned int flags = altvalue; + 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) + { + altvalue = 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 = altvalue; + 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 (__builtin_expect (! GLRO(dl_bind_not), 1)) *resultp = value; } - (*mcount_fct) (retaddr, 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 altvalue = 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) + { + unsigned int flags = altvalue; + 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) + { + altvalue = 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; } @@ -214,9 +394,45 @@ profile_fixup ( #endif /* PROF && ELF_MACHINE_NO_PLT */ -/* This macro is defined in dl-machine.h to define the entry point called - by the PLT. The `fixup' function above does the real work, but a little - more twiddling is needed to get the stack right and jump to the address - finally resolved. */ +#include <stdio.h> +void +ARCH_FIXUP_ATTRIBUTE +_dl_call_pltexit (struct link_map *l, ElfW(Word) reloc_offset, + 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_offset / sizeof (PLTREL)]; + 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; + + /* 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); + } -ELF_MACHINE_RUNTIME_TRAMPOLINE + afct = afct->next; + } +#endif +} |