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Sun, 10 Apr 2016 14:15:06 -0700 Received: by char.us.oracle.com (Postfix, from userid 1000) id CD3006A00FB; Sun, 10 Apr 2016 17:15:04 -0400 (EDT) From: Konrad Rzeszutek Wilk To: xen-devel@lists.xenproject.org, konrad@kernel.org, sasha.levin@oracle.com, andrew.cooper3@citrix.com, ross.lagerwall@citrix.com, mpohlack@amazon.de Date: Sun, 10 Apr 2016 17:14:41 -0400 Message-Id: <1460322896-1115-10-git-send-email-konrad.wilk@oracle.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1460322896-1115-1-git-send-email-konrad.wilk@oracle.com> References: <1460322896-1115-1-git-send-email-konrad.wilk@oracle.com> X-Source-IP: userv0021.oracle.com [156.151.31.71] Cc: Keir Fraser , Julien Grall , Stefano Stabellini , Jan Beulich , Konrad Rzeszutek Wilk Subject: [Xen-devel] [PATCH v7 09/24] xsplice: Implement payload loading X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Ross Lagerwall Add support for loading xsplice payloads. This is somewhat similar to the Linux kernel module loader, implementing the following steps: - Verify the elf file. - Parse the elf file. - Allocate a region of memory mapped within a free area of [xen_virt_end, XEN_VIRT_END]. - Copy allocated sections into the new region. Split them in three regions - .text, .data, and .rodata. MUST have at least .text. - Resolve section symbols. All other symbols must be absolute addresses. (Note that patch titled "xsplice,symbols: Implement symbol name resolution on address" implements that) - Perform relocations. - Secure the the regions (.text,.data,.rodata) with proper permissions. We capitalize on the vmalloc callback API (see patch titled: "rm/x86/vmap: Add vmalloc_xen, vfree_xen and vm_init_type") to allocate a region of memory within the [xen_virt_end, XEN_VIRT_END] for the code. We also use the "x86/mm: Introduce modify_xen_mappings()" to change the virtual address page-table permissions. Signed-off-by: Ross Lagerwall Signed-off-by: Konrad Rzeszutek Wilk Reviewed-by: Andrew Cooper Acked-by: Julien Grall --- Cc: Stefano Stabellini Cc: Julien Grall Cc: Keir Fraser Cc: Jan Beulich Cc: Andrew Cooper v2: - Change the 'xsplice_patch_func' structure layout/size. - Add more error checking. Fix memory leak. - Move elf_resolve and elf_perform relocs in elf file. - Print the payload address and pages in keyhandler. v3: - Make it build under ARM - Build it without using the return_ macro. - Add fixes from Ross. - Add the _return macro back - but only use it during debug builds. - Remove the macro, prefix arch_ on arch specific calls. v4: - Move alloc_payload to arch specific file. - Use void* instead of uint8_t, use const - Add copyrights - Unroll the vmap code to add ASSERT. Change while to not incur potential long error loop - Use vmalloc/vfree cb APIs - Secure .text pages to be RX instead of RWX. v5: - Fix allocation of virtual addresses only allowing one page to be allocated. - Create .text, .data, and .rodata regions with different permissions. - Make the find_space_t not a typedef to pointer to a function. - Allocate memory in here. v6: Drop parentheses on typedefs. - s/an xSplice/a xSplice/ - Rebase on "vmap: Add vmalloc_cb" - Rebase on "vmap: Add vmalloc_type and vm_init_type" - s/uint8_t/void/ on load_addr - Set xsplice_elf on stack without using memset. v7: - Changed the check on delta = elf->hdr->e_shoff + elf->hdr->e_shnum * elf->hdr->e_shentsize; The sections can be right at the back of the file (different linker!), so the failing conditional for 'if (delta >= elf->len)' is incorrect and should have been '>'. - Changed dprintk(XENLOG_DEBUG to XENLOG_ERR, then back to DEBUG. Converted some of the printk to dprintk. - Rebase on " arm/x86/vmap: Add vmalloc_xen, vfree_xen and vm_init_type" - Changed some of the printk XENLOG_ERR to XENLOG_DEBUG - Check the idx in the relocation to make sure it is within bounds and implemented. - Use "x86/mm: Introduce modify_xen_mappings()" - Introduce PRIxElfAddr - Check for overflow in R_X86_64_PC32 - Return -EOPNOTSUPP if we don't support types in ELF64_R_TYPE --- --- xen/arch/arm/Makefile | 1 + xen/arch/arm/xsplice.c | 54 ++++++++++ xen/arch/x86/Makefile | 1 + xen/arch/x86/xsplice.c | 188 +++++++++++++++++++++++++++++++++++ xen/common/xsplice.c | 226 +++++++++++++++++++++++++++++++++++++++++- xen/common/xsplice_elf.c | 124 ++++++++++++++++++++++- xen/include/xen/elfstructs.h | 4 + xen/include/xen/xsplice.h | 29 ++++++ xen/include/xen/xsplice_elf.h | 9 +- 9 files changed, 631 insertions(+), 5 deletions(-) create mode 100644 xen/arch/arm/xsplice.c create mode 100644 xen/arch/x86/xsplice.c diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile index 0328b50..eae5cb3 100644 --- a/xen/arch/arm/Makefile +++ b/xen/arch/arm/Makefile @@ -40,6 +40,7 @@ obj-y += device.o obj-y += decode.o obj-y += processor.o obj-y += smc.o +obj-$(CONFIG_XSPLICE) += xsplice.o #obj-bin-y += ....o diff --git a/xen/arch/arm/xsplice.c b/xen/arch/arm/xsplice.c new file mode 100644 index 0000000..4465244 --- /dev/null +++ b/xen/arch/arm/xsplice.c @@ -0,0 +1,54 @@ +/* + * Copyright (C) 2016 Citrix Systems R&D Ltd. + */ +#include +#include +#include +#include + +int arch_xsplice_verify_elf(const struct xsplice_elf *elf) +{ + return -ENOSYS; +} + +int arch_xsplice_perform_rel(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela) +{ + return -ENOSYS; +} + +int arch_xsplice_perform_rela(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela) +{ + return -ENOSYS; +} + +void *arch_xsplice_alloc_payload(unsigned int pages) +{ + return NULL; +} + +int arch_xsplice_secure(void *va, unsigned int pages, enum va_type type) +{ + return -ENOSYS; +} + +void arch_xsplice_free_payload(void *va) +{ +} + +void arch_xsplice_init(void) +{ +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile index 729065b..8a6a7d5 100644 --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -64,6 +64,7 @@ obj-y += vm_event.o obj-y += xstate.o obj-$(crash_debug) += gdbstub.o +obj-$(CONFIG_XSPLICE) += xsplice.o x86_emulate.o: x86_emulate/x86_emulate.c x86_emulate/x86_emulate.h diff --git a/xen/arch/x86/xsplice.c b/xen/arch/x86/xsplice.c new file mode 100644 index 0000000..8ee6c5c --- /dev/null +++ b/xen/arch/x86/xsplice.c @@ -0,0 +1,188 @@ +/* + * Copyright (C) 2016 Citrix Systems R&D Ltd. + */ + +#include +#include +#include +#include +#include +#include +#include + +int arch_xsplice_verify_elf(const struct xsplice_elf *elf) +{ + + const Elf_Ehdr *hdr = elf->hdr; + + if ( hdr->e_machine != EM_X86_64 ) + { + dprintk(XENLOG_ERR, XSPLICE "%s: Unsupported ELF Machine type!\n", + elf->name); + return -EOPNOTSUPP; + } + + return 0; +} + +int arch_xsplice_perform_rel(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela) +{ + dprintk(XENLOG_ERR, XSPLICE "%s: SHT_REL relocation unsupported\n", + elf->name); + return -EOPNOTSUPP; +} + +int arch_xsplice_perform_rela(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela) +{ + const Elf_RelA *r; + unsigned int symndx, i; + uint64_t val; + uint8_t *dest; + + if ( !rela->sec->sh_entsize || !rela->sec->sh_size || + rela->sec->sh_entsize != sizeof(Elf_RelA) ) + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: Section relative header is corrupted!\n", + elf->name); + return -EINVAL; + } + + for ( i = 0; i < (rela->sec->sh_size / rela->sec->sh_entsize); i++ ) + { + r = rela->data + i * rela->sec->sh_entsize; + if ( (unsigned long)r > (unsigned long)(elf->hdr + elf->len) ) + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: Relative entry %u in %s is past end!\n", + elf->name, i, rela->name); + return -EINVAL; + } + + symndx = ELF64_R_SYM(r->r_info); + if ( symndx > elf->nsym ) + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: Relative symbol wants symbol@%u which is past end!\n", + elf->name, symndx); + return -EINVAL; + } + + dest = base->load_addr + r->r_offset; + val = r->r_addend + elf->sym[symndx].sym->st_value; + + switch ( ELF64_R_TYPE(r->r_info) ) + { + case R_X86_64_NONE: + break; + + case R_X86_64_64: + *(uint64_t *)dest = val; + break; + + case R_X86_64_PLT32: + /* + * Xen uses -fpic which normally uses PLT relocations + * except that it sets visibility to hidden which means + * that they are not used. However, when gcc cannot + * inline memcpy it emits memcpy with default visibility + * which then creates a PLT relocation. It can just be + * treated the same as R_X86_64_PC32. + */ + /* Fall through */ + case R_X86_64_PC32: + val -= (uint64_t)dest; + *(uint32_t *)dest = val; + if ( (s64)val != *(s32 *)dest ) + { + printk(XENLOG_DEBUG XSPLICE "%s: Overflow in relocation %u in %s for %s!\n", + elf->name, i, rela->name, base->name); + return -EOVERFLOW; + } + break; + + default: + printk(XENLOG_DEBUG XSPLICE "%s: Unhandled relocation %lu\n", + elf->name, ELF64_R_TYPE(r->r_info)); + return -EOPNOTSUPP; + } + } + + return 0; +} + +/* + * The function prepares a xSplice payload by allocating space which + * then can be used for loading the allocated sections, resolving symbols, + * performing relocations, etc. + */ +void *arch_xsplice_alloc_payload(unsigned int pages) +{ + unsigned int i; + void *p; + + ASSERT(pages); + + p = vmalloc_xen(pages * PAGE_SIZE); + WARN_ON(!p); + if ( p ) + { + /* By default they are PAGE_HYPERVISOR aka PAGE_HYPERVISOR_RWX.*/ + for ( i = 0; i < pages; i++ ) + clear_page(p + (i * PAGE_SIZE) ); + } + return p; +} + +/* + * Once the resolving symbols, performing relocations, etc is complete + * we secure the memory by putting in the proper page table attributes + * for the desired type. + */ +int arch_xsplice_secure(void *va, unsigned int pages, enum va_type type) +{ + unsigned long start = (unsigned long)va; + int flag; + + ASSERT(va); + ASSERT(pages); + + if ( type == XSPLICE_VA_RX ) /* PAGE_HYPERVISOR_RX */ + flag = _PAGE_PRESENT; + else if ( type == XSPLICE_VA_RW ) /* PAGE_HYPERVISOR_RW */ + flag = _PAGE_RW | _PAGE_NX | _PAGE_PRESENT; + else /* PAGE_HYPERVISOR_RO */ + flag = _PAGE_NX | _PAGE_PRESENT; + + /* The ones we are allowed to modify are: _PAGE_NX|_PAGE_RW|_PAGE_PRESENT */ + modify_xen_mappings(start, start + pages * PAGE_SIZE, flag); + + return 0; +} + +void arch_xsplice_free_payload(void *va) +{ + vfree_xen(va); +} + +void arch_xsplice_init(void) +{ + void *start, *end; + + start = (void *)xen_virt_end; + end = (void *)(XEN_VIRT_END - NR_CPUS * PAGE_SIZE); + + BUG_ON(end <= start); + + vm_init_type(VMAP_XEN, start, end); +} +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c index 120fd5c..cbee264 100644 --- a/xen/common/xsplice.c +++ b/xen/common/xsplice.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include @@ -28,6 +29,13 @@ struct payload { uint32_t state; /* One of the XSPLICE_STATE_*. */ int32_t rc; /* 0 or -XEN_EXX. */ struct list_head list; /* Linked to 'payload_list'. */ + void *text_addr; /* Virtual address of .text. */ + size_t text_size; /* .. and its size. */ + void *rw_addr; /* Virtual address of .data. */ + size_t rw_size; /* .. and its size (if any). */ + void *ro_addr; /* Virtual address of .rodata. */ + size_t ro_size; /* .. and its size (if any). */ + size_t pages; /* Total pages for [text,rw,ro]_addr */ char name[XEN_XSPLICE_NAME_SIZE]; /* Name of it. */ }; @@ -85,19 +93,215 @@ static struct payload *find_payload(const char *name) return found; } +/* + * Functions related to XEN_SYSCTL_XSPLICE_UPLOAD (see xsplice_upload), and + * freeing payload (XEN_SYSCTL_XSPLICE_ACTION:XSPLICE_ACTION_UNLOAD). + */ + +static void free_payload_data(struct payload *payload) +{ + /* Set to zero until "move_payload". */ + if ( !payload->text_addr ) + return; + + arch_xsplice_free_payload(payload->text_addr); + + payload->text_addr = NULL; + payload->ro_addr = NULL; + payload->rw_addr = NULL; + payload->pages = 0; +} + +/* +* calc_section computes the size (taking into account section alignment). +* +* It also modifies sh_entsize with the offset of from the start of +* virtual address space. This is used in move_payload to figure out the +* destination location. +*/ +static void calc_section(struct xsplice_elf_sec *sec, size_t *size) +{ + Elf_Shdr *s = sec->sec; + size_t align_size; + + align_size = ROUNDUP(*size, s->sh_addralign); + s->sh_entsize = align_size; + + *size = s->sh_size + align_size; +} + +static int move_payload(struct payload *payload, struct xsplice_elf *elf) +{ + uint8_t *buf; + unsigned int i; + size_t size = 0; + + /* Compute text regions. */ + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + if ( (elf->sec[i].sec->sh_flags & (SHF_ALLOC|SHF_EXECINSTR)) == + (SHF_ALLOC|SHF_EXECINSTR) ) + calc_section(&elf->sec[i], &payload->text_size); + } + + /* Compute rw data. */ + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) && + !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) && + (elf->sec[i].sec->sh_flags & SHF_WRITE) ) + calc_section(&elf->sec[i], &payload->rw_size); + } + + /* Compute ro data. */ + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) && + !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) && + !(elf->sec[i].sec->sh_flags & SHF_WRITE) ) + calc_section(&elf->sec[i], &payload->ro_size); + } + + /* Do not accept wx. */ + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + if ( !(elf->sec[i].sec->sh_flags & SHF_ALLOC) && + (elf->sec[i].sec->sh_flags & SHF_EXECINSTR) && + (elf->sec[i].sec->sh_flags & SHF_WRITE) ) + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: No WX sections!\n", elf->name); + return -EINVAL; + } + } + + /* + * Total of all three regions - RX, RW, and RO. We have to have + * keep them in seperate pages so we PAGE_ALIGN the RX and RW to have + * them on seperate pages. The last one will by default fall on its + * own page. + */ + size = PAGE_ALIGN(payload->text_size) + PAGE_ALIGN(payload->rw_size) + + payload->ro_size; + + size = PFN_UP(size); + buf = arch_xsplice_alloc_payload(size); + if ( !buf ) + { + printk(XENLOG_ERR XSPLICE "%s: Could not allocate memory for payload!\n", + elf->name); + return -ENOMEM; + } + payload->pages = size; + payload->text_addr = buf; + payload->rw_addr = payload->text_addr + PAGE_ALIGN(payload->text_size); + payload->ro_addr = payload->rw_addr + PAGE_ALIGN(payload->rw_size); + + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + if ( elf->sec[i].sec->sh_flags & SHF_ALLOC ) + { + if ( (elf->sec[i].sec->sh_flags & SHF_EXECINSTR) ) + buf = payload->text_addr; + else if ( (elf->sec[i].sec->sh_flags & SHF_WRITE) ) + buf = payload->rw_addr; + else + buf = payload->ro_addr; + + elf->sec[i].load_addr = buf + elf->sec[i].sec->sh_entsize; + + /* Don't copy NOBITS - such as BSS. */ + if ( elf->sec[i].sec->sh_type != SHT_NOBITS ) + { + memcpy(elf->sec[i].load_addr, elf->sec[i].data, + elf->sec[i].sec->sh_size); + dprintk(XENLOG_DEBUG, XSPLICE "%s: Loaded %s at 0x%p\n", + elf->name, elf->sec[i].name, elf->sec[i].load_addr); + } + } + } + + return 0; +} + +static int secure_payload(struct payload *payload, struct xsplice_elf *elf) +{ + int rc; + unsigned int text_pages, rw_pages, ro_pages; + + text_pages = PFN_UP(payload->text_size); + ASSERT(text_pages); + + rc = arch_xsplice_secure(payload->text_addr, text_pages, XSPLICE_VA_RX); + if ( rc ) + return rc; + + rw_pages = PFN_UP(payload->rw_size); + if ( rw_pages ) + { + rc = arch_xsplice_secure(payload->rw_addr, rw_pages, XSPLICE_VA_RW); + if ( rc ) + return rc; + } + + ro_pages = PFN_UP(payload->ro_size); + if ( ro_pages ) + { + rc = arch_xsplice_secure(payload->ro_addr, ro_pages, XSPLICE_VA_RO); + } + + ASSERT(ro_pages + rw_pages + text_pages == payload->pages); + + return rc; +} + static void free_payload(struct payload *data) { ASSERT(spin_is_locked(&payload_lock)); list_del(&data->list); payload_cnt--; payload_version++; + free_payload_data(data); xfree(data); } +static int load_payload_data(struct payload *payload, void *raw, size_t len) +{ + struct xsplice_elf elf = { .name = payload->name, .len = len }; + int rc = 0; + + rc = xsplice_elf_load(&elf, raw); + if ( rc ) + goto out; + + rc = move_payload(payload, &elf); + if ( rc ) + goto out; + + rc = xsplice_elf_resolve_symbols(&elf); + if ( rc ) + goto out; + + rc = xsplice_elf_perform_relocs(&elf); + if ( rc ) + goto out; + + rc = secure_payload(payload, &elf); + + out: + if ( rc ) + free_payload_data(payload); + + /* Free our temporary data structure. */ + xsplice_elf_free(&elf); + + return rc; +} + static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload) { struct payload *data = NULL, *found; char n[XEN_XSPLICE_NAME_SIZE]; + void *raw_data = NULL; int rc; rc = verify_payload(upload, n); @@ -125,9 +329,20 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload) goto out; } - rc = 0; + rc = -ENOMEM; + raw_data = vmalloc(upload->size); + if ( !raw_data ) + goto out; + + rc = -EFAULT; + if ( __copy_from_guest(raw_data, upload->payload, upload->size) ) + goto out; memcpy(data->name, n, strlen(n)); + rc = load_payload_data(data, raw_data, upload->size); + if ( rc ) + goto out; + data->state = XSPLICE_STATE_CHECKED; INIT_LIST_HEAD(&data->list); @@ -138,6 +353,8 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload) out: spin_unlock(&payload_lock); + vfree(raw_data); + if ( rc ) xfree(data); @@ -379,8 +596,9 @@ static void xsplice_printall(unsigned char key) } list_for_each_entry ( data, &payload_list, list ) - printk(" name=%s state=%s(%d)\n", data->name, - state2str(data->state), data->state); + printk(" name=%s state=%s(%d) %p (.data=%p, .rodata=%p) using %zu pages.\n", + data->name, state2str(data->state), data->state, data->text_addr, + data->rw_addr, data->ro_addr, data->pages); spin_unlock(&payload_lock); } @@ -388,6 +606,8 @@ static void xsplice_printall(unsigned char key) static int __init xsplice_init(void) { register_keyhandler('x', xsplice_printall, "print xsplicing info", 1); + + arch_xsplice_init(); return 0; } __initcall(xsplice_init); diff --git a/xen/common/xsplice_elf.c b/xen/common/xsplice_elf.c index ffa5c95..7262fc2 100644 --- a/xen/common/xsplice_elf.c +++ b/xen/common/xsplice_elf.c @@ -101,7 +101,7 @@ static int elf_resolve_sections(struct xsplice_elf *elf, const void *data) } elf->symtab = &sec[i]; - + elf->symtab_idx = i; /* * elf->symtab->sec->sh_link would point to the right section * but we hadn't finished parsing all the sections. @@ -249,9 +249,127 @@ static int elf_get_sym(struct xsplice_elf *elf, const void *data) return 0; } +int xsplice_elf_resolve_symbols(struct xsplice_elf *elf) +{ + unsigned int i; + int rc = 0; + + /* + * The first entry of an ELF symbol table is the "undefined symbol index". + * aka reserved so we skip it. + */ + ASSERT(elf->sym); + + for ( i = 1; i < elf->nsym; i++ ) + { + uint16_t idx = elf->sym[i].sym->st_shndx; + + rc = 0; + switch ( idx ) + { + case SHN_COMMON: + printk(XENLOG_DEBUG XSPLICE "%s: Unexpected common symbol: %s\n", + elf->name, elf->sym[i].name); + rc = -EINVAL; + break; + + case SHN_UNDEF: + printk(XENLOG_DEBUG XSPLICE "%s: Unknown symbol: %s\n", + elf->name, elf->sym[i].name); + rc = -ENOENT; + break; + + case SHN_ABS: + dprintk(XENLOG_DEBUG, XSPLICE "%s: Absolute symbol: %s => %#"PRIxElfAddr"\n", + elf->name, elf->sym[i].name, elf->sym[i].sym->st_value); + break; + + default: + /* SHN_COMMON and SHN_ABS are above. */ + if ( idx > SHN_LORESERVE ) + rc = -EOPNOTSUPP; + /* SHN_UNDEF (0) above. */ + else if ( idx > elf->hdr->e_shnum && idx < SHN_LORESERVE ) + rc = -EINVAL; + + if ( rc ) + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: Unknown type=%#"PRIx16"\n", + elf->name, idx); + break; + } + + if ( !(elf->sec[idx].sec->sh_flags & SHF_ALLOC) ) + break; + + elf->sym[i].sym->st_value += (unsigned long)elf->sec[idx].load_addr; + if ( elf->sym[i].name ) + printk(XENLOG_DEBUG XSPLICE "%s: Symbol resolved: %s => %#"PRIxElfAddr"(%s)\n", + elf->name, elf->sym[i].name, + elf->sym[i].sym->st_value, elf->sec[idx].name); + } + + if ( rc ) + break; + } + + return rc; +} + +int xsplice_elf_perform_relocs(struct xsplice_elf *elf) +{ + struct xsplice_elf_sec *rela, *base; + unsigned int i; + int rc = 0; + + /* + * The first entry of an ELF symbol table is the "undefined symbol index". + * aka reserved so we skip it. + */ + ASSERT(elf->sym); + + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + rela = &elf->sec[i]; + + if ( (rela->sec->sh_type != SHT_RELA) && + (rela->sec->sh_type != SHT_REL) ) + continue; + + /* Is it a valid relocation section? */ + if ( rela->sec->sh_info >= elf->hdr->e_shnum ) + continue; + + base = &elf->sec[rela->sec->sh_info]; + + /* Don't relocate non-allocated sections. */ + if ( !(base->sec->sh_flags & SHF_ALLOC) ) + continue; + + if ( rela->sec->sh_link != elf->symtab_idx ) + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: Relative link of %s is incorrect (%d, expected=%d)\n", + elf->name, rela->name, rela->sec->sh_link, elf->symtab_idx); + rc = -EINVAL; + break; + } + + if ( rela->sec->sh_type == SHT_RELA ) + rc = arch_xsplice_perform_rela(elf, base, rela); + else /* SHT_REL */ + rc = arch_xsplice_perform_rel(elf, base, rela); + + if ( rc ) + break; + } + + return rc; +} + static int xsplice_header_check(const struct xsplice_elf *elf) { const Elf_Ehdr *hdr = elf->hdr; + int rc; if ( sizeof(*elf->hdr) > elf->len ) { @@ -276,6 +394,10 @@ static int xsplice_header_check(const struct xsplice_elf *elf) return -EOPNOTSUPP; } + rc = arch_xsplice_verify_elf(elf); + if ( rc ) + return rc; + if ( elf->hdr->e_shstrndx == SHN_UNDEF ) { dprintk(XENLOG_DEBUG, XSPLICE "%s: Section name idx is undefined!?\n", diff --git a/xen/include/xen/elfstructs.h b/xen/include/xen/elfstructs.h index 85f35ed..be55985 100644 --- a/xen/include/xen/elfstructs.h +++ b/xen/include/xen/elfstructs.h @@ -472,6 +472,8 @@ typedef struct { #endif #if defined(ELFSIZE) && (ELFSIZE == 32) +#define PRIxElfAddr "08x" + #define Elf_Ehdr Elf32_Ehdr #define Elf_Phdr Elf32_Phdr #define Elf_Shdr Elf32_Shdr @@ -497,6 +499,8 @@ typedef struct { #define AuxInfo Aux32Info #elif defined(ELFSIZE) && (ELFSIZE == 64) +#define PRIxElfAddr "lx" + #define Elf_Ehdr Elf64_Ehdr #define Elf_Phdr Elf64_Phdr #define Elf_Shdr Elf64_Shdr diff --git a/xen/include/xen/xsplice.h b/xen/include/xen/xsplice.h index cd805a8..83e4f31 100644 --- a/xen/include/xen/xsplice.h +++ b/xen/include/xen/xsplice.h @@ -6,6 +6,9 @@ #ifndef __XEN_XSPLICE_H__ #define __XEN_XSPLICE_H__ +struct xsplice_elf; +struct xsplice_elf_sec; +struct xsplice_elf_sym; struct xen_sysctl_xsplice_op; #ifdef CONFIG_XSPLICE @@ -15,6 +18,32 @@ struct xen_sysctl_xsplice_op; int xsplice_op(struct xen_sysctl_xsplice_op *); +/* Arch hooks. */ +int arch_xsplice_verify_elf(const struct xsplice_elf *elf); +int arch_xsplice_perform_rel(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela); +int arch_xsplice_perform_rela(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela); +enum va_type { + XSPLICE_VA_RX, /* .text */ + XSPLICE_VA_RW, /* .data */ + XSPLICE_VA_RO, /* .rodata */ +}; + +#include +void *arch_xsplice_alloc_payload(unsigned int pages); + +/* + * Function to secure the allocate pages (from arch_xsplice_alloc_payload) + * with the right page permissions. + */ +int arch_xsplice_secure(void *va, unsigned int pages, enum va_type types); + +void arch_xsplice_free_payload(void *va); + +void arch_xsplice_init(void); #else #include /* For -ENOSYS */ diff --git a/xen/include/xen/xsplice_elf.h b/xen/include/xen/xsplice_elf.h index 89acb77..6892f59 100644 --- a/xen/include/xen/xsplice_elf.h +++ b/xen/include/xen/xsplice_elf.h @@ -15,6 +15,8 @@ struct xsplice_elf_sec { elf_resolve_section_names. */ const void *data; /* Pointer to the section (done by elf_resolve_sections). */ + void *load_addr; /* A pointer to the allocated destination. + Done by load_payload_data. */ }; struct xsplice_elf_sym { @@ -29,8 +31,10 @@ struct xsplice_elf { struct xsplice_elf_sec *sec; /* Array of sections, allocated by us. */ struct xsplice_elf_sym *sym; /* Array of symbols , allocated by us. */ unsigned int nsym; - const struct xsplice_elf_sec *symtab;/* Pointer to .symtab section - aka to sec[x]. */ + const struct xsplice_elf_sec *symtab;/* Pointer to .symtab section - aka to + sec[symtab_idx]. */ const struct xsplice_elf_sec *strtab;/* Pointer to .strtab section - aka to sec[y]. */ + unsigned int symtab_idx; }; const struct xsplice_elf_sec *xsplice_elf_sec_by_name(const struct xsplice_elf *elf, @@ -38,6 +42,9 @@ const struct xsplice_elf_sec *xsplice_elf_sec_by_name(const struct xsplice_elf * int xsplice_elf_load(struct xsplice_elf *elf, const void *data); void xsplice_elf_free(struct xsplice_elf *elf); +int xsplice_elf_resolve_symbols(struct xsplice_elf *elf); +int xsplice_elf_perform_relocs(struct xsplice_elf *elf); + #endif /* __XEN_XSPLICE_ELF_H__ */ /*