diff --git a/Documentation/livepatch/module-elf-format.rst b/Documentation/livepatch/module-elf-format.rst index 2a591e6f8e6c..8c6b894c4661 100644 --- a/Documentation/livepatch/module-elf-format.rst +++ b/Documentation/livepatch/module-elf-format.rst @@ -14,8 +14,7 @@ This document outlines the Elf format requirements that livepatch modules must f 4. Livepatch symbols 4.1 A livepatch module's symbol table 4.2 Livepatch symbol format - 5. Architecture-specific sections - 6. Symbol table and Elf section access + 5. Symbol table and Elf section access 1. Background and motivation ============================ @@ -298,17 +297,7 @@ Examples: Note that the 'Ndx' (Section index) for these symbols is SHN_LIVEPATCH (0xff20). "OS" means OS-specific. -5. Architecture-specific sections -================================= -Architectures may override arch_klp_init_object_loaded() to perform -additional arch-specific tasks when a target module loads, such as applying -arch-specific sections. On x86 for example, we must apply per-object -.altinstructions and .parainstructions sections when a target module loads. -These sections must be prefixed with ".klp.arch.$objname." so that they can -be easily identified when iterating through a patch module's Elf sections -(See arch/x86/kernel/livepatch.c for a complete example). - -6. Symbol table and Elf section access +5. Symbol table and Elf section access ====================================== A livepatch module's symbol table is accessible through module->symtab. diff --git a/MAINTAINERS b/MAINTAINERS index 465210f17948..02cbbe88b65f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9936,10 +9936,12 @@ S: Maintained T: git git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching.git F: Documentation/ABI/testing/sysfs-kernel-livepatch F: Documentation/livepatch/ +F: arch/powerpc/include/asm/livepatch.h +F: arch/s390/include/asm/livepatch.h F: arch/x86/include/asm/livepatch.h -F: arch/x86/kernel/livepatch.c F: include/linux/livepatch.h F: kernel/livepatch/ +F: lib/livepatch/ F: samples/livepatch/ F: tools/testing/selftests/livepatch/ diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h index a470f1fa9f2a..324438889fe1 100644 --- a/arch/s390/include/asm/uaccess.h +++ b/arch/s390/include/asm/uaccess.h @@ -276,6 +276,6 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo } int copy_to_user_real(void __user *dest, void *src, unsigned long count); -void s390_kernel_write(void *dst, const void *src, size_t size); +void *s390_kernel_write(void *dst, const void *src, size_t size); #endif /* __S390_UACCESS_H */ diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c index ba8f19bb438b..4055f1c49814 100644 --- a/arch/s390/kernel/module.c +++ b/arch/s390/kernel/module.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -174,10 +175,12 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, } static int apply_rela_bits(Elf_Addr loc, Elf_Addr val, - int sign, int bits, int shift) + int sign, int bits, int shift, + void *(*write)(void *dest, const void *src, size_t len)) { unsigned long umax; long min, max; + void *dest = (void *)loc; if (val & ((1UL << shift) - 1)) return -ENOEXEC; @@ -194,26 +197,33 @@ static int apply_rela_bits(Elf_Addr loc, Elf_Addr val, return -ENOEXEC; } - if (bits == 8) - *(unsigned char *) loc = val; - else if (bits == 12) - *(unsigned short *) loc = (val & 0xfff) | + if (bits == 8) { + unsigned char tmp = val; + write(dest, &tmp, 1); + } else if (bits == 12) { + unsigned short tmp = (val & 0xfff) | (*(unsigned short *) loc & 0xf000); - else if (bits == 16) - *(unsigned short *) loc = val; - else if (bits == 20) - *(unsigned int *) loc = (val & 0xfff) << 16 | - (val & 0xff000) >> 4 | - (*(unsigned int *) loc & 0xf00000ff); - else if (bits == 32) - *(unsigned int *) loc = val; - else if (bits == 64) - *(unsigned long *) loc = val; + write(dest, &tmp, 2); + } else if (bits == 16) { + unsigned short tmp = val; + write(dest, &tmp, 2); + } else if (bits == 20) { + unsigned int tmp = (val & 0xfff) << 16 | + (val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff); + write(dest, &tmp, 4); + } else if (bits == 32) { + unsigned int tmp = val; + write(dest, &tmp, 4); + } else if (bits == 64) { + unsigned long tmp = val; + write(dest, &tmp, 8); + } return 0; } static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, - const char *strtab, struct module *me) + const char *strtab, struct module *me, + void *(*write)(void *dest, const void *src, size_t len)) { struct mod_arch_syminfo *info; Elf_Addr loc, val; @@ -241,17 +251,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, case R_390_64: /* Direct 64 bit. */ val += rela->r_addend; if (r_type == R_390_8) - rc = apply_rela_bits(loc, val, 0, 8, 0); + rc = apply_rela_bits(loc, val, 0, 8, 0, write); else if (r_type == R_390_12) - rc = apply_rela_bits(loc, val, 0, 12, 0); + rc = apply_rela_bits(loc, val, 0, 12, 0, write); else if (r_type == R_390_16) - rc = apply_rela_bits(loc, val, 0, 16, 0); + rc = apply_rela_bits(loc, val, 0, 16, 0, write); else if (r_type == R_390_20) - rc = apply_rela_bits(loc, val, 1, 20, 0); + rc = apply_rela_bits(loc, val, 1, 20, 0, write); else if (r_type == R_390_32) - rc = apply_rela_bits(loc, val, 0, 32, 0); + rc = apply_rela_bits(loc, val, 0, 32, 0, write); else if (r_type == R_390_64) - rc = apply_rela_bits(loc, val, 0, 64, 0); + rc = apply_rela_bits(loc, val, 0, 64, 0, write); break; case R_390_PC16: /* PC relative 16 bit. */ case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */ @@ -260,15 +270,15 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, case R_390_PC64: /* PC relative 64 bit. */ val += rela->r_addend - loc; if (r_type == R_390_PC16) - rc = apply_rela_bits(loc, val, 1, 16, 0); + rc = apply_rela_bits(loc, val, 1, 16, 0, write); else if (r_type == R_390_PC16DBL) - rc = apply_rela_bits(loc, val, 1, 16, 1); + rc = apply_rela_bits(loc, val, 1, 16, 1, write); else if (r_type == R_390_PC32DBL) - rc = apply_rela_bits(loc, val, 1, 32, 1); + rc = apply_rela_bits(loc, val, 1, 32, 1, write); else if (r_type == R_390_PC32) - rc = apply_rela_bits(loc, val, 1, 32, 0); + rc = apply_rela_bits(loc, val, 1, 32, 0, write); else if (r_type == R_390_PC64) - rc = apply_rela_bits(loc, val, 1, 64, 0); + rc = apply_rela_bits(loc, val, 1, 64, 0, write); break; case R_390_GOT12: /* 12 bit GOT offset. */ case R_390_GOT16: /* 16 bit GOT offset. */ @@ -283,33 +293,33 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, case R_390_GOTPLT64: /* 64 bit offset to jump slot. */ case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */ if (info->got_initialized == 0) { - Elf_Addr *gotent; + Elf_Addr *gotent = me->core_layout.base + + me->arch.got_offset + + info->got_offset; - gotent = me->core_layout.base + me->arch.got_offset + - info->got_offset; - *gotent = val; + write(gotent, &val, sizeof(*gotent)); info->got_initialized = 1; } val = info->got_offset + rela->r_addend; if (r_type == R_390_GOT12 || r_type == R_390_GOTPLT12) - rc = apply_rela_bits(loc, val, 0, 12, 0); + rc = apply_rela_bits(loc, val, 0, 12, 0, write); else if (r_type == R_390_GOT16 || r_type == R_390_GOTPLT16) - rc = apply_rela_bits(loc, val, 0, 16, 0); + rc = apply_rela_bits(loc, val, 0, 16, 0, write); else if (r_type == R_390_GOT20 || r_type == R_390_GOTPLT20) - rc = apply_rela_bits(loc, val, 1, 20, 0); + rc = apply_rela_bits(loc, val, 1, 20, 0, write); else if (r_type == R_390_GOT32 || r_type == R_390_GOTPLT32) - rc = apply_rela_bits(loc, val, 0, 32, 0); + rc = apply_rela_bits(loc, val, 0, 32, 0, write); else if (r_type == R_390_GOT64 || r_type == R_390_GOTPLT64) - rc = apply_rela_bits(loc, val, 0, 64, 0); + rc = apply_rela_bits(loc, val, 0, 64, 0, write); else if (r_type == R_390_GOTENT || r_type == R_390_GOTPLTENT) { val += (Elf_Addr) me->core_layout.base - loc; - rc = apply_rela_bits(loc, val, 1, 32, 1); + rc = apply_rela_bits(loc, val, 1, 32, 1, write); } break; case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */ @@ -320,25 +330,29 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */ case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */ if (info->plt_initialized == 0) { - unsigned int *ip; - ip = me->core_layout.base + me->arch.plt_offset + - info->plt_offset; - ip[0] = 0x0d10e310; /* basr 1,0 */ - ip[1] = 0x100a0004; /* lg 1,10(1) */ + unsigned int insn[5]; + unsigned int *ip = me->core_layout.base + + me->arch.plt_offset + + info->plt_offset; + + insn[0] = 0x0d10e310; /* basr 1,0 */ + insn[1] = 0x100a0004; /* lg 1,10(1) */ if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) { unsigned int *ij; ij = me->core_layout.base + me->arch.plt_offset + me->arch.plt_size - PLT_ENTRY_SIZE; - ip[2] = 0xa7f40000 + /* j __jump_r1 */ + insn[2] = 0xa7f40000 + /* j __jump_r1 */ (unsigned int)(u16) (((unsigned long) ij - 8 - (unsigned long) ip) / 2); } else { - ip[2] = 0x07f10000; /* br %r1 */ + insn[2] = 0x07f10000; /* br %r1 */ } - ip[3] = (unsigned int) (val >> 32); - ip[4] = (unsigned int) val; + insn[3] = (unsigned int) (val >> 32); + insn[4] = (unsigned int) val; + + write(ip, insn, sizeof(insn)); info->plt_initialized = 1; } if (r_type == R_390_PLTOFF16 || @@ -357,17 +371,17 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, val += rela->r_addend - loc; } if (r_type == R_390_PLT16DBL) - rc = apply_rela_bits(loc, val, 1, 16, 1); + rc = apply_rela_bits(loc, val, 1, 16, 1, write); else if (r_type == R_390_PLTOFF16) - rc = apply_rela_bits(loc, val, 0, 16, 0); + rc = apply_rela_bits(loc, val, 0, 16, 0, write); else if (r_type == R_390_PLT32DBL) - rc = apply_rela_bits(loc, val, 1, 32, 1); + rc = apply_rela_bits(loc, val, 1, 32, 1, write); else if (r_type == R_390_PLT32 || r_type == R_390_PLTOFF32) - rc = apply_rela_bits(loc, val, 0, 32, 0); + rc = apply_rela_bits(loc, val, 0, 32, 0, write); else if (r_type == R_390_PLT64 || r_type == R_390_PLTOFF64) - rc = apply_rela_bits(loc, val, 0, 64, 0); + rc = apply_rela_bits(loc, val, 0, 64, 0, write); break; case R_390_GOTOFF16: /* 16 bit offset to GOT. */ case R_390_GOTOFF32: /* 32 bit offset to GOT. */ @@ -375,20 +389,20 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, val = val + rela->r_addend - ((Elf_Addr) me->core_layout.base + me->arch.got_offset); if (r_type == R_390_GOTOFF16) - rc = apply_rela_bits(loc, val, 0, 16, 0); + rc = apply_rela_bits(loc, val, 0, 16, 0, write); else if (r_type == R_390_GOTOFF32) - rc = apply_rela_bits(loc, val, 0, 32, 0); + rc = apply_rela_bits(loc, val, 0, 32, 0, write); else if (r_type == R_390_GOTOFF64) - rc = apply_rela_bits(loc, val, 0, 64, 0); + rc = apply_rela_bits(loc, val, 0, 64, 0, write); break; case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */ case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */ val = (Elf_Addr) me->core_layout.base + me->arch.got_offset + rela->r_addend - loc; if (r_type == R_390_GOTPC) - rc = apply_rela_bits(loc, val, 1, 32, 0); + rc = apply_rela_bits(loc, val, 1, 32, 0, write); else if (r_type == R_390_GOTPCDBL) - rc = apply_rela_bits(loc, val, 1, 32, 1); + rc = apply_rela_bits(loc, val, 1, 32, 1, write); break; case R_390_COPY: case R_390_GLOB_DAT: /* Create GOT entry. */ @@ -412,9 +426,10 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, return 0; } -int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, +static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, - struct module *me) + struct module *me, + void *(*write)(void *dest, const void *src, size_t len)) { Elf_Addr base; Elf_Sym *symtab; @@ -430,13 +445,27 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, n = sechdrs[relsec].sh_size / sizeof(Elf_Rela); for (i = 0; i < n; i++, rela++) { - rc = apply_rela(rela, base, symtab, strtab, me); + rc = apply_rela(rela, base, symtab, strtab, me, write); if (rc) return rc; } return 0; } +int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, + unsigned int symindex, unsigned int relsec, + struct module *me) +{ + bool early = me->state == MODULE_STATE_UNFORMED; + void *(*write)(void *, const void *, size_t) = memcpy; + + if (!early) + write = s390_kernel_write; + + return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, + write); +} + int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *me) diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c index de7ca4b6718f..22a0be655f27 100644 --- a/arch/s390/mm/maccess.c +++ b/arch/s390/mm/maccess.c @@ -55,19 +55,22 @@ static notrace long s390_kernel_write_odd(void *dst, const void *src, size_t siz */ static DEFINE_SPINLOCK(s390_kernel_write_lock); -void notrace s390_kernel_write(void *dst, const void *src, size_t size) +notrace void *s390_kernel_write(void *dst, const void *src, size_t size) { + void *tmp = dst; unsigned long flags; long copied; spin_lock_irqsave(&s390_kernel_write_lock, flags); while (size) { - copied = s390_kernel_write_odd(dst, src, size); - dst += copied; + copied = s390_kernel_write_odd(tmp, src, size); + tmp += copied; src += copied; size -= copied; } spin_unlock_irqrestore(&s390_kernel_write_lock, flags); + + return dst; } static int __no_sanitize_address __memcpy_real(void *dest, void *src, size_t count) diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index 0f40eccbd759..375ab720e4aa 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -362,3 +362,19 @@ void __init check_bugs(void) void apply_alternatives(struct alt_instr *start, struct alt_instr *end) { } + +void *text_poke(void *addr, const void *opcode, size_t len) +{ + /* + * In UML, the only reference to this function is in + * apply_relocate_add(), which shouldn't ever actually call this + * because UML doesn't have live patching. + */ + WARN_ON(1); + + return memcpy(addr, opcode, len); +} + +void text_poke_sync(void) +{ +} diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 2a7c3afa62e2..8ef4369a4f06 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -90,7 +90,6 @@ obj-$(CONFIG_X86_MPPARSE) += mpparse.o obj-y += apic/ obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups_32.o obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o -obj-$(CONFIG_LIVEPATCH) += livepatch.o obj-$(CONFIG_FUNCTION_TRACER) += ftrace_$(BITS).o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o diff --git a/arch/x86/kernel/livepatch.c b/arch/x86/kernel/livepatch.c deleted file mode 100644 index 6a68e41206e7..000000000000 --- a/arch/x86/kernel/livepatch.c +++ /dev/null @@ -1,53 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0-or-later -/* - * livepatch.c - x86-specific Kernel Live Patching Core - */ - -#include -#include -#include -#include - -/* Apply per-object alternatives. Based on x86 module_finalize() */ -void arch_klp_init_object_loaded(struct klp_patch *patch, - struct klp_object *obj) -{ - int cnt; - struct klp_modinfo *info; - Elf_Shdr *s, *alt = NULL, *para = NULL; - void *aseg, *pseg; - const char *objname; - char sec_objname[MODULE_NAME_LEN]; - char secname[KSYM_NAME_LEN]; - - info = patch->mod->klp_info; - objname = obj->name ? obj->name : "vmlinux"; - - /* See livepatch core code for BUILD_BUG_ON() explanation */ - BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); - - for (s = info->sechdrs; s < info->sechdrs + info->hdr.e_shnum; s++) { - /* Apply per-object .klp.arch sections */ - cnt = sscanf(info->secstrings + s->sh_name, - ".klp.arch.%55[^.].%127s", - sec_objname, secname); - if (cnt != 2) - continue; - if (strcmp(sec_objname, objname)) - continue; - if (!strcmp(".altinstructions", secname)) - alt = s; - if (!strcmp(".parainstructions", secname)) - para = s; - } - - if (alt) { - aseg = (void *) alt->sh_addr; - apply_alternatives(aseg, aseg + alt->sh_size); - } - - if (para) { - pseg = (void *) para->sh_addr; - apply_paravirt(pseg, pseg + para->sh_size); - } -} diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index d5c72cb877b3..23c95a53d20e 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -126,11 +127,12 @@ int apply_relocate(Elf32_Shdr *sechdrs, return 0; } #else /*X86_64*/ -int apply_relocate_add(Elf64_Shdr *sechdrs, +static int __apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, - struct module *me) + struct module *me, + void *(*write)(void *dest, const void *src, size_t len)) { unsigned int i; Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; @@ -162,19 +164,19 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, case R_X86_64_64: if (*(u64 *)loc != 0) goto invalid_relocation; - *(u64 *)loc = val; + write(loc, &val, 8); break; case R_X86_64_32: if (*(u32 *)loc != 0) goto invalid_relocation; - *(u32 *)loc = val; + write(loc, &val, 4); if (val != *(u32 *)loc) goto overflow; break; case R_X86_64_32S: if (*(s32 *)loc != 0) goto invalid_relocation; - *(s32 *)loc = val; + write(loc, &val, 4); if ((s64)val != *(s32 *)loc) goto overflow; break; @@ -183,7 +185,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, if (*(u32 *)loc != 0) goto invalid_relocation; val -= (u64)loc; - *(u32 *)loc = val; + write(loc, &val, 4); #if 0 if ((s64)val != *(s32 *)loc) goto overflow; @@ -193,7 +195,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, if (*(u64 *)loc != 0) goto invalid_relocation; val -= (u64)loc; - *(u64 *)loc = val; + write(loc, &val, 8); break; default: pr_err("%s: Unknown rela relocation: %llu\n", @@ -215,6 +217,33 @@ overflow: me->name); return -ENOEXEC; } + +int apply_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + int ret; + bool early = me->state == MODULE_STATE_UNFORMED; + void *(*write)(void *, const void *, size_t) = memcpy; + + if (!early) { + write = text_poke; + mutex_lock(&text_mutex); + } + + ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, + write); + + if (!early) { + text_poke_sync(); + mutex_unlock(&text_mutex); + } + + return ret; +} + #endif int module_finalize(const Elf_Ehdr *hdr, diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h index e894e74905f3..2614247a9781 100644 --- a/include/linux/livepatch.h +++ b/include/linux/livepatch.h @@ -195,9 +195,6 @@ struct klp_patch { int klp_enable_patch(struct klp_patch *); -void arch_klp_init_object_loaded(struct klp_patch *patch, - struct klp_object *obj); - /* Called from the module loader during module coming/going states */ int klp_module_coming(struct module *mod); void klp_module_going(struct module *mod); @@ -234,6 +231,11 @@ void klp_shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor); struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id); struct klp_state *klp_get_prev_state(unsigned long id); +int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, + const char *shstrtab, const char *strtab, + unsigned int symindex, unsigned int secindex, + const char *objname); + #else /* !CONFIG_LIVEPATCH */ static inline int klp_module_coming(struct module *mod) { return 0; } @@ -242,6 +244,15 @@ static inline bool klp_patch_pending(struct task_struct *task) { return false; } static inline void klp_update_patch_state(struct task_struct *task) {} static inline void klp_copy_process(struct task_struct *child) {} +static inline +int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, + const char *shstrtab, const char *strtab, + unsigned int symindex, unsigned int secindex, + const char *objname) +{ + return 0; +} + #endif /* CONFIG_LIVEPATCH */ #endif /* _LINUX_LIVEPATCH_H_ */ diff --git a/include/linux/module.h b/include/linux/module.h index d849d06e4d44..2e6670860d27 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -866,14 +866,6 @@ extern int module_sysfs_initialized; #define __MODULE_STRING(x) __stringify(x) -#ifdef CONFIG_STRICT_MODULE_RWX -extern void module_enable_ro(const struct module *mod, bool after_init); -extern void module_disable_ro(const struct module *mod); -#else -static inline void module_enable_ro(const struct module *mod, bool after_init) { } -static inline void module_disable_ro(const struct module *mod) { } -#endif - #ifdef CONFIG_GENERIC_BUG void module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *, struct module *); diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index c3512e7e0801..f76fdb925532 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -191,18 +191,21 @@ static int klp_find_object_symbol(const char *objname, const char *name, return -EINVAL; } -static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) +static int klp_resolve_symbols(Elf64_Shdr *sechdrs, const char *strtab, + unsigned int symndx, Elf_Shdr *relasec, + const char *sec_objname) { - int i, cnt, vmlinux, ret; - char objname[MODULE_NAME_LEN]; - char symname[KSYM_NAME_LEN]; - char *strtab = pmod->core_kallsyms.strtab; + int i, cnt, ret; + char sym_objname[MODULE_NAME_LEN]; + char sym_name[KSYM_NAME_LEN]; Elf_Rela *relas; Elf_Sym *sym; unsigned long sympos, addr; + bool sym_vmlinux; + bool sec_vmlinux = !strcmp(sec_objname, "vmlinux"); /* - * Since the field widths for objname and symname in the sscanf() + * Since the field widths for sym_objname and sym_name in the sscanf() * call are hard-coded and correspond to MODULE_NAME_LEN and * KSYM_NAME_LEN respectively, we must make sure that MODULE_NAME_LEN * and KSYM_NAME_LEN have the values we expect them to have. @@ -216,27 +219,40 @@ static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) relas = (Elf_Rela *) relasec->sh_addr; /* For each rela in this klp relocation section */ for (i = 0; i < relasec->sh_size / sizeof(Elf_Rela); i++) { - sym = pmod->core_kallsyms.symtab + ELF_R_SYM(relas[i].r_info); + sym = (Elf64_Sym *)sechdrs[symndx].sh_addr + ELF_R_SYM(relas[i].r_info); if (sym->st_shndx != SHN_LIVEPATCH) { pr_err("symbol %s is not marked as a livepatch symbol\n", strtab + sym->st_name); return -EINVAL; } - /* Format: .klp.sym.objname.symname,sympos */ + /* Format: .klp.sym.sym_objname.sym_name,sympos */ cnt = sscanf(strtab + sym->st_name, ".klp.sym.%55[^.].%127[^,],%lu", - objname, symname, &sympos); + sym_objname, sym_name, &sympos); if (cnt != 3) { pr_err("symbol %s has an incorrectly formatted name\n", strtab + sym->st_name); return -EINVAL; } + sym_vmlinux = !strcmp(sym_objname, "vmlinux"); + + /* + * Prevent module-specific KLP rela sections from referencing + * vmlinux symbols. This helps prevent ordering issues with + * module special section initializations. Presumably such + * symbols are exported and normal relas can be used instead. + */ + if (!sec_vmlinux && sym_vmlinux) { + pr_err("invalid access to vmlinux symbol '%s' from module-specific livepatch relocation section", + sym_name); + return -EINVAL; + } + /* klp_find_object_symbol() treats a NULL objname as vmlinux */ - vmlinux = !strcmp(objname, "vmlinux"); - ret = klp_find_object_symbol(vmlinux ? NULL : objname, - symname, sympos, &addr); + ret = klp_find_object_symbol(sym_vmlinux ? NULL : sym_objname, + sym_name, sympos, &addr); if (ret) return ret; @@ -246,54 +262,59 @@ static int klp_resolve_symbols(Elf_Shdr *relasec, struct module *pmod) return 0; } -static int klp_write_object_relocations(struct module *pmod, - struct klp_object *obj) +/* + * At a high-level, there are two types of klp relocation sections: those which + * reference symbols which live in vmlinux; and those which reference symbols + * which live in other modules. This function is called for both types: + * + * 1) When a klp module itself loads, the module code calls this function to + * write vmlinux-specific klp relocations (.klp.rela.vmlinux.* sections). + * These relocations are written to the klp module text to allow the patched + * code/data to reference unexported vmlinux symbols. They're written as + * early as possible to ensure that other module init code (.e.g., + * jump_label_apply_nops) can access any unexported vmlinux symbols which + * might be referenced by the klp module's special sections. + * + * 2) When a to-be-patched module loads -- or is already loaded when a + * corresponding klp module loads -- klp code calls this function to write + * module-specific klp relocations (.klp.rela.{module}.* sections). These + * are written to the klp module text to allow the patched code/data to + * reference symbols which live in the to-be-patched module or one of its + * module dependencies. Exported symbols are supported, in addition to + * unexported symbols, in order to enable late module patching, which allows + * the to-be-patched module to be loaded and patched sometime *after* the + * klp module is loaded. + */ +int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs, + const char *shstrtab, const char *strtab, + unsigned int symndx, unsigned int secndx, + const char *objname) { - int i, cnt, ret = 0; - const char *objname, *secname; + int cnt, ret; char sec_objname[MODULE_NAME_LEN]; - Elf_Shdr *sec; + Elf_Shdr *sec = sechdrs + secndx; - if (WARN_ON(!klp_is_object_loaded(obj))) + /* + * Format: .klp.rela.sec_objname.section_name + * See comment in klp_resolve_symbols() for an explanation + * of the selected field width value. + */ + cnt = sscanf(shstrtab + sec->sh_name, ".klp.rela.%55[^.]", + sec_objname); + if (cnt != 1) { + pr_err("section %s has an incorrectly formatted name\n", + shstrtab + sec->sh_name); return -EINVAL; - - objname = klp_is_module(obj) ? obj->name : "vmlinux"; - - /* For each klp relocation section */ - for (i = 1; i < pmod->klp_info->hdr.e_shnum; i++) { - sec = pmod->klp_info->sechdrs + i; - secname = pmod->klp_info->secstrings + sec->sh_name; - if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) - continue; - - /* - * Format: .klp.rela.sec_objname.section_name - * See comment in klp_resolve_symbols() for an explanation - * of the selected field width value. - */ - cnt = sscanf(secname, ".klp.rela.%55[^.]", sec_objname); - if (cnt != 1) { - pr_err("section %s has an incorrectly formatted name\n", - secname); - ret = -EINVAL; - break; - } - - if (strcmp(objname, sec_objname)) - continue; - - ret = klp_resolve_symbols(sec, pmod); - if (ret) - break; - - ret = apply_relocate_add(pmod->klp_info->sechdrs, - pmod->core_kallsyms.strtab, - pmod->klp_info->symndx, i, pmod); - if (ret) - break; } - return ret; + if (strcmp(objname ? objname : "vmlinux", sec_objname)) + return 0; + + ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname); + if (ret) + return ret; + + return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod); } /* @@ -724,10 +745,27 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func) func->old_sympos ? func->old_sympos : 1); } -/* Arches may override this to finish any remaining arch-specific tasks */ -void __weak arch_klp_init_object_loaded(struct klp_patch *patch, - struct klp_object *obj) +static int klp_apply_object_relocs(struct klp_patch *patch, + struct klp_object *obj) { + int i, ret; + struct klp_modinfo *info = patch->mod->klp_info; + + for (i = 1; i < info->hdr.e_shnum; i++) { + Elf_Shdr *sec = info->sechdrs + i; + + if (!(sec->sh_flags & SHF_RELA_LIVEPATCH)) + continue; + + ret = klp_apply_section_relocs(patch->mod, info->sechdrs, + info->secstrings, + patch->mod->core_kallsyms.strtab, + info->symndx, i, obj->name); + if (ret) + return ret; + } + + return 0; } /* parts of the initialization that is done only when the object is loaded */ @@ -737,21 +775,18 @@ static int klp_init_object_loaded(struct klp_patch *patch, struct klp_func *func; int ret; - mutex_lock(&text_mutex); - - module_disable_ro(patch->mod); - ret = klp_write_object_relocations(patch->mod, obj); - if (ret) { - module_enable_ro(patch->mod, true); - mutex_unlock(&text_mutex); - return ret; + if (klp_is_module(obj)) { + /* + * Only write module-specific relocations here + * (.klp.rela.{module}.*). vmlinux-specific relocations were + * written earlier during the initialization of the klp module + * itself. + */ + ret = klp_apply_object_relocs(patch, obj); + if (ret) + return ret; } - arch_klp_init_object_loaded(patch, obj); - module_enable_ro(patch->mod, true); - - mutex_unlock(&text_mutex); - klp_for_each_func(obj, func) { ret = klp_find_object_symbol(obj->name, func->old_name, func->old_sympos, @@ -1139,6 +1174,11 @@ int klp_module_coming(struct module *mod) if (WARN_ON(mod->state != MODULE_STATE_COMING)) return -EINVAL; + if (!strcmp(mod->name, "vmlinux")) { + pr_err("vmlinux.ko: invalid module name"); + return -EINVAL; + } + mutex_lock(&klp_mutex); /* * Each module has to know that klp_module_coming() diff --git a/kernel/module.c b/kernel/module.c index be5413903d20..bca993c5f1bc 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2000,20 +2000,7 @@ static void frob_writable_data(const struct module_layout *layout, (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); } -/* livepatching wants to disable read-only so it can frob module. */ -void module_disable_ro(const struct module *mod) -{ - if (!rodata_enabled) - return; - - frob_text(&mod->core_layout, set_memory_rw); - frob_rodata(&mod->core_layout, set_memory_rw); - frob_ro_after_init(&mod->core_layout, set_memory_rw); - frob_text(&mod->init_layout, set_memory_rw); - frob_rodata(&mod->init_layout, set_memory_rw); -} - -void module_enable_ro(const struct module *mod, bool after_init) +static void module_enable_ro(const struct module *mod, bool after_init) { if (!rodata_enabled) return; @@ -2041,6 +2028,7 @@ static void module_enable_nx(const struct module *mod) #else /* !CONFIG_STRICT_MODULE_RWX */ static void module_enable_nx(const struct module *mod) { } +static void module_enable_ro(const struct module *mod, bool after_init) {} #endif /* CONFIG_STRICT_MODULE_RWX */ static void module_enable_x(const struct module *mod) { @@ -2337,11 +2325,13 @@ static int apply_relocations(struct module *mod, const struct load_info *info) if (!(info->sechdrs[infosec].sh_flags & SHF_ALLOC)) continue; - /* Livepatch relocation sections are applied by livepatch */ if (info->sechdrs[i].sh_flags & SHF_RELA_LIVEPATCH) - continue; - - if (info->sechdrs[i].sh_type == SHT_REL) + err = klp_apply_section_relocs(mod, info->sechdrs, + info->secstrings, + info->strtab, + info->index.sym, i, + NULL); + else if (info->sechdrs[i].sh_type == SHT_REL) err = apply_relocate(info->sechdrs, info->strtab, info->index.sym, i, mod); else if (info->sechdrs[i].sh_type == SHT_RELA)