From e26ed573b62f69d9813e72fda4ee3da6eaf4d7b7 Mon Sep 17 00:00:00 2001 From: Joakim Tjernlund Date: Fri, 5 Jan 2007 10:20:37 +0000 Subject: Support SecurePLTs for PowerPC. You need a toolchain that supports config option --enable-secureplt. The assembler must also supports R_PPC_REL16* relocations. gcc 4.1.1 and binutils 2.17 is known to do this. --- ldso/ldso/powerpc/dl-startup.h | 7 +++ ldso/ldso/powerpc/dl-sysdep.h | 52 +++++++++++++------ ldso/ldso/powerpc/elfinterp.c | 113 +++++++++++++++++++++++++---------------- 3 files changed, 114 insertions(+), 58 deletions(-) (limited to 'ldso/ldso') diff --git a/ldso/ldso/powerpc/dl-startup.h b/ldso/ldso/powerpc/dl-startup.h index becfa191e..a5a8a83f2 100644 --- a/ldso/ldso/powerpc/dl-startup.h +++ b/ldso/ldso/powerpc/dl-startup.h @@ -16,8 +16,15 @@ asm( " bl _dl_start@local\n" /* Perform relocation */ /* Save the address of the apps entry point in CTR register */ " mtctr 3\n" /* application entry point */ +#ifdef HAVE_ASM_PPC_REL16 + " bcl 20,31,1f\n" + "1: mflr 31\n" + " addis 31,31,_GLOBAL_OFFSET_TABLE_-1b@ha\n" + " addi 31,31,_GLOBAL_OFFSET_TABLE_-1b@l\n" +#else " bl _GLOBAL_OFFSET_TABLE_-4@local\n" /* Put our GOT pointer in r31, */ " mflr 31\n" +#endif " addi 1,1,16\n" /* Restore SP */ " lwz 7,_dl_skip_args@got(31)\n" /* load EA of _dl_skip_args */ " lwz 7,0(7)\n" /* Load word from _dl_skip_args */ diff --git a/ldso/ldso/powerpc/dl-sysdep.h b/ldso/ldso/powerpc/dl-sysdep.h index a06aa8aff..44f9c955c 100644 --- a/ldso/ldso/powerpc/dl-sysdep.h +++ b/ldso/ldso/powerpc/dl-sysdep.h @@ -89,23 +89,38 @@ void _dl_init_got(unsigned long *lpnt,struct elf_resolve *tpnt); DT_RELA table. */ #define ELF_MACHINE_PLTREL_OVERLAP 1 +/* Return the value of the GOT pointer. */ +static inline Elf32_Addr * __attribute__ ((const)) +ppc_got (void) +{ + Elf32_Addr *got; +#ifdef HAVE_ASM_PPC_REL16 + asm (" bcl 20,31,1f\n" + "1:mflr %0\n" + " addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n" + " addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n" + : "=b" (got) : : "lr"); +#else + asm (" bl _GLOBAL_OFFSET_TABLE_-4@local" + : "=l" (got)); +#endif + return got; +} + /* Return the link-time address of _DYNAMIC, stored as the first value in the GOT. */ -static inline Elf32_Addr +static inline Elf32_Addr __attribute__ ((const)) elf_machine_dynamic (void) { - Elf32_Addr *got; - asm (" bl _GLOBAL_OFFSET_TABLE_-4@local" - : "=l"(got)); - return *got; + return *ppc_got(); } /* Return the run-time load address of the shared object. */ -static inline Elf32_Addr +static inline Elf32_Addr __attribute__ ((const)) elf_machine_load_address (void) { - unsigned int *got; - unsigned int *branchaddr; + Elf32_Addr *branchaddr; + Elf32_Addr runtime_dynamic; /* This is much harder than you'd expect. Possibly I'm missing something. The 'obvious' way: @@ -136,19 +151,17 @@ elf_machine_load_address (void) the address ourselves. That gives us the following code: */ /* Get address of the 'b _DYNAMIC@local'... */ - asm ("bl 0f ;" + asm ("bcl 20,31,0f;" "b _DYNAMIC@local;" "0:" : "=l"(branchaddr)); - /* ... and the address of the GOT. */ - asm (" bl _GLOBAL_OFFSET_TABLE_-4@local" - : "=l"(got)); - /* So now work out the difference between where the branch actually points, and the offset of that location in memory from the start of the file. */ - return ((Elf32_Addr)branchaddr - *got - + ((int)(*branchaddr << 6 & 0xffffff00) >> 6)); + runtime_dynamic = ((Elf32_Addr) branchaddr + + ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6)); + + return runtime_dynamic - elf_machine_dynamic (); } static inline void @@ -163,3 +176,12 @@ elf_machine_relative (Elf32_Addr load_off, const Elf32_Addr rel_addr, *reloc_addr = load_off + rpnt->r_addend; } while (--relative_count); } + +#define ARCH_NUM 1 +#define DT_PPC_GOT_IDX (DT_NUM + OS_NUM) + +#define ARCH_DYNAMIC_INFO(dpnt, dynamic, debug_addr) \ +do { \ +if (dpnt->d_tag == DT_PPC_GOT) \ + dynamic[DT_PPC_GOT_IDX] = dpnt->d_un.d_ptr; \ +} while (0) diff --git a/ldso/ldso/powerpc/elfinterp.c b/ldso/ldso/powerpc/elfinterp.c index d2a164287..b48625a37 100644 --- a/ldso/ldso/powerpc/elfinterp.c +++ b/ldso/ldso/powerpc/elfinterp.c @@ -41,6 +41,12 @@ void _dl_init_got(unsigned long *plt,struct elf_resolve *tpnt) Elf32_Word rel_offset_words; Elf32_Word dlrr = (Elf32_Word) _dl_linux_resolve; + if (tpnt->dynamic_info[DT_JMPREL] == 0) + return; + if (tpnt->dynamic_info[DT_PPC_GOT_IDX] != 0) { + tpnt->dynamic_info[DT_PPC_GOT_IDX] += tpnt->loadaddr; + return; + } num_plt_entries = tpnt->dynamic_info[DT_PLTRELSZ] / sizeof(ELF_RELOC); rel_offset_words = PLT_DATA_START_WORDS(num_plt_entries); data_words = (Elf32_Word) (plt + rel_offset_words); @@ -148,32 +154,35 @@ unsigned long _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry) if (_dl_debug_reloc && _dl_debug_detail) _dl_dprintf(_dl_debug_file, "%x\n", finaladdr); #endif - delta = finaladdr - (Elf32_Word)reloc_addr; - if (delta<<6>>6 == delta) { - *reloc_addr = OPCODE_B(delta); - } else if (finaladdr <= 0x01fffffc) { - *reloc_addr = OPCODE_BA (finaladdr); + if (tpnt->dynamic_info[DT_PPC_GOT_IDX] != 0) { + *reloc_addr = finaladdr; } else { - /* Warning: we don't handle double-sized PLT entries */ - Elf32_Word *plt, *data_words, index, offset; + delta = finaladdr - (Elf32_Word)reloc_addr; + if (delta<<6>>6 == delta) { + *reloc_addr = OPCODE_B(delta); + } else if (finaladdr <= 0x01fffffc) { + *reloc_addr = OPCODE_BA (finaladdr); + } else { + /* Warning: we don't handle double-sized PLT entries */ + Elf32_Word *plt, *data_words, index, offset; + + plt = (Elf32_Word *)tpnt->dynamic_info[DT_PLTGOT]; + offset = reloc_addr - plt; + index = (offset - PLT_INITIAL_ENTRY_WORDS)/2; + data_words = (Elf32_Word *)tpnt->data_words; + reloc_addr += 1; - plt = (Elf32_Word *)tpnt->dynamic_info[DT_PLTGOT]; - offset = reloc_addr - plt; - index = (offset - PLT_INITIAL_ENTRY_WORDS)/2; - data_words = (Elf32_Word *)tpnt->data_words; - reloc_addr += 1; + data_words[index] = finaladdr; + PPC_SYNC; + *reloc_addr = OPCODE_B ((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1)) * 4); + } - data_words[index] = finaladdr; + /* instructions were modified */ + PPC_DCBST(reloc_addr); PPC_SYNC; - *reloc_addr = OPCODE_B ((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1)) * 4); + PPC_ICBI(reloc_addr); + PPC_ISYNC; } - - /* instructions were modified */ - PPC_DCBST(reloc_addr); - PPC_SYNC; - PPC_ICBI(reloc_addr); - PPC_ISYNC; - return finaladdr; } @@ -219,28 +228,33 @@ _dl_do_reloc (struct elf_resolve *tpnt,struct dyn_elf *scope, goto out_nocode; /* No code code modified */ case R_PPC_JMP_SLOT: { - Elf32_Sword delta = finaladdr - (Elf32_Word)reloc_addr; - if (delta<<6>>6 == delta) { - *reloc_addr = OPCODE_B(delta); - } else if (finaladdr <= 0x01fffffc) { - *reloc_addr = OPCODE_BA (finaladdr); + if (tpnt->dynamic_info[DT_PPC_GOT_IDX] != 0) { + *reloc_addr = finaladdr; + goto out_nocode; /* No code code modified */ } else { - /* Warning: we don't handle double-sized PLT entries */ - Elf32_Word *plt, *data_words, index, offset; - - plt = (Elf32_Word *)tpnt->dynamic_info[DT_PLTGOT]; - offset = reloc_addr - plt; - index = (offset - PLT_INITIAL_ENTRY_WORDS)/2; - data_words = (Elf32_Word *)tpnt->data_words; - - data_words[index] = finaladdr; - reloc_addr[0] = OPCODE_LI(11,index*4); - reloc_addr[1] = OPCODE_B((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1)) * 4); - - /* instructions were modified */ - PPC_DCBST(reloc_addr+1); - PPC_SYNC; - PPC_ICBI(reloc_addr+1); + Elf32_Sword delta = finaladdr - (Elf32_Word)reloc_addr; + if (delta<<6>>6 == delta) { + *reloc_addr = OPCODE_B(delta); + } else if (finaladdr <= 0x01fffffc) { + *reloc_addr = OPCODE_BA (finaladdr); + } else { + /* Warning: we don't handle double-sized PLT entries */ + Elf32_Word *plt, *data_words, index, offset; + + plt = (Elf32_Word *)tpnt->dynamic_info[DT_PLTGOT]; + offset = reloc_addr - plt; + index = (offset - PLT_INITIAL_ENTRY_WORDS)/2; + data_words = (Elf32_Word *)tpnt->data_words; + + data_words[index] = finaladdr; + reloc_addr[0] = OPCODE_LI(11,index*4); + reloc_addr[1] = OPCODE_B((PLT_LONGBRANCH_ENTRY_WORDS - (offset+1)) * 4); + + /* instructions were modified */ + PPC_DCBST(reloc_addr+1); + PPC_SYNC; + PPC_ICBI(reloc_addr+1); + } } break; } @@ -309,9 +323,22 @@ void _dl_parse_lazy_relocation_information(struct dyn_elf *rpnt, Elf32_Word *plt, offset, i, num_plt_entries, rel_offset_words; num_plt_entries = rel_size / sizeof(ELF_RELOC); + plt = (Elf32_Word *)tpnt->dynamic_info[DT_PLTGOT]; + if (tpnt->dynamic_info[DT_PPC_GOT_IDX] != 0) { + /* Secure PLT */ + Elf32_Addr *got = (Elf32_Addr *)tpnt->dynamic_info[DT_PPC_GOT_IDX]; + Elf32_Word dlrr = (Elf32_Word) _dl_linux_resolve; + + got[1] = (Elf32_Addr) dlrr; + got[2] = (Elf32_Addr) tpnt; + + /* Relocate everything in .plt by the load address offset. */ + while (num_plt_entries-- != 0) + *plt++ += tpnt->loadaddr; + return; + } rel_offset_words = PLT_DATA_START_WORDS(num_plt_entries); - plt = (Elf32_Word *)tpnt->dynamic_info[DT_PLTGOT]; /* Set up the lazy PLT entries. */ offset = PLT_INITIAL_ENTRY_WORDS; 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