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Wed, 27 Apr 2016 12:28:00 -0700 Received: by char.us.oracle.com (Postfix, from userid 1000) id 1CFA96A012B; Wed, 27 Apr 2016 15:27:58 -0400 (EDT) From: Konrad Rzeszutek Wilk To: konrad@kernel.org, xen-devel@lists.xenproject.org, sasha.levin@oracle.com, andrew.cooper3@citrix.com, ross.lagerwall@citrix.com, mpohlack@amazon.de Date: Wed, 27 Apr 2016 15:27:05 -0400 Message-Id: <1461785241-4481-9-git-send-email-konrad.wilk@oracle.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1461785241-4481-1-git-send-email-konrad.wilk@oracle.com> References: <1461785241-4481-1-git-send-email-konrad.wilk@oracle.com> X-Source-IP: userv0021.oracle.com [156.151.31.71] Cc: Julien Grall , Stefano Stabellini , Keir Fraser , Jan Beulich , Konrad Rzeszutek Wilk Subject: [Xen-devel] [PATCH v10 08/24] 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 v[z|m]alloc_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 Acked-by: Julien Grall Reviewed-by: Jan Beulich --- 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 v8: - Change dprintk and printk XENLOG_DEBUG to XENLOG_ERR - Convert four of the printks in dprintk. v9: - Rebase on different spinlock usage in xsplice_upload. - Do proper bound and overflow checking. - Added 'const' on [text,ro,rw]_addr. - Made 'calc_section' and 'move_payload' use an dynamically allocated array for computed offsets instead of modifying sh_entsize. - Remove arch_xsplice_[alloc_payload|free] and use vzalloc_xen and vfree. - Collapse for loop in move_payload. - Move xsplice.o in Makefile - Add more checks in arch_xsplice_perform_rela (r_offset and sh_size % sh_entsize) - Use int32_t and int64_t in arch_xsplice_perform_rela. - Tighten the list of sh_flags we check - Use intermediate on 'buf' so that we can do 'const void *' - Use intermediate in xsplice_elf_resolve_symbols for 'const' of elf->sym. - Fail if (and only) SHF_ALLOC and SHT_NOBITS section is seen. v10: - Dropped Andrew's Reviewed-by - Expand arch_xsplice_verify_elf to check EI_CLASS and EI_ABIVERSION - In arch_xsplice_perform_rela drop check against !rela->sec->sh_entsize, add extra checks against r_offset + sizeof(type) neccessating an extra goto statement. - Make arch_xsplice_init be __init. - In free_payload_data check against ->pages instead of ->text_addr. - In move_payload use 'void *' instead of 'uint8_t *', use xmalloc_array for offset, expand on the 'Do Nothing' comment and the 'Ignoring'; Use vmalloc instead of vzalloc - which means for .bss we also use memset; drop the unary + when calculating address for rw_buf; Fix indention (I hope? I don't see an issue); also use offset[i] =UINT_MAX for sections we are not going to allocate or memcpy - and assert if we do hit those. - In xsplice_elf_resolve_symbols move check against !(elf->sec[idx].sec->sh_flags & SHF_ALLOC) back to what it was in v8. - In xsplice_elf_perform_relocs drop comment about first ELF symbol. - Different if/else if in upload function. v10.1 - patch posted as inline reply within v9 patchset: - Add check for EI_DATA and ditch EI_ABIVERSION out of platform specific checks. - In elf_resolve_symbols use const ElfSym and temporary variable (st_value) which is used to set value in const (and only in one place will we unconst the sym); change %#"PRIx.." to #x or #lx types as we don't use Elf types anymore. - Make the r_offset check be within switch statements to guard against NONE relocations. - Fix the 'else if' spacing issue; - Use different message when idx in symbols is out of bounds. v10.2 - patch posted as inline reply against the v10.1 above. - In 'move_payload' simplify loop calculating size. - In xsplice_elf_resolve_symbols use Elf_Addr instead of unsigned long. Also use %#"PRIx" to work on ARM32 --- xen/arch/arm/Makefile | 1 + xen/arch/arm/xsplice.c | 46 +++++++++ xen/arch/x86/Makefile | 1 + xen/arch/x86/xsplice.c | 173 +++++++++++++++++++++++++++++++ xen/common/xsplice.c | 233 +++++++++++++++++++++++++++++++++++++++++- xen/common/xsplice_elf.c | 118 +++++++++++++++++++++ xen/include/xen/elfstructs.h | 4 + xen/include/xen/xsplice.h | 24 +++++ xen/include/xen/xsplice_elf.h | 11 +- 9 files changed, 606 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-$(CONFIG_XSPLICE) += xsplice.o #obj-bin-y += ....o diff --git a/xen/arch/arm/xsplice.c b/xen/arch/arm/xsplice.c new file mode 100644 index 0000000..8cb7767 --- /dev/null +++ b/xen/arch/arm/xsplice.c @@ -0,0 +1,46 @@ +/* + * Copyright (C) 2016 Citrix Systems R&D Ltd. + */ +#include +#include +#include +#include +#include + +int arch_xsplice_verify_elf(const struct xsplice_elf *elf) +{ + return -ENOSYS; +} + +int arch_xsplice_perform_rel(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela) +{ + return -ENOSYS; +} + +int arch_xsplice_perform_rela(struct xsplice_elf *elf, + const struct xsplice_elf_sec *base, + const struct xsplice_elf_sec *rela) +{ + return -ENOSYS; +} + +int arch_xsplice_secure(const void *va, unsigned int pages, enum va_type type) +{ + return -ENOSYS; +} + +void __init arch_xsplice_init(void) +{ +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile index 729065b..f74fd2c 100644 --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -61,6 +61,7 @@ obj-y += x86_emulate.o obj-y += tboot.o obj-y += hpet.o obj-y += vm_event.o +obj-$(CONFIG_XSPLICE) += xsplice.o obj-y += xstate.o obj-$(crash_debug) += gdbstub.o diff --git a/xen/arch/x86/xsplice.c b/xen/arch/x86/xsplice.c new file mode 100644 index 0000000..82618f7 --- /dev/null +++ b/xen/arch/x86/xsplice.c @@ -0,0 +1,173 @@ +/* + * Copyright (C) 2016 Citrix Systems R&D Ltd. + */ + +#include +#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 || + hdr->e_ident[EI_CLASS] != ELFCLASS64 || + hdr->e_ident[EI_DATA] != ELFDATA2LSB ) + { + 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; + + /* Nothing to do. */ + if ( !rela->sec->sh_size ) + return 0; + + if ( rela->sec->sh_entsize < sizeof(Elf_RelA) || + rela->sec->sh_size % rela->sec->sh_entsize ) + { + dprintk(XENLOG_ERR, 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; + + symndx = ELF64_R_SYM(r->r_info); + + if ( symndx > elf->nsym ) + { + dprintk(XENLOG_ERR, XSPLICE "%s: Relative relocation 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: + if ( r->r_offset >= base->sec->sh_size || + (r->r_offset + sizeof(uint64_t)) > base->sec->sh_size ) + goto bad_offset; + + *(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. + */ + case R_X86_64_PC32: + if ( r->r_offset >= base->sec->sh_size || + (r->r_offset + sizeof(uint32_t)) > base->sec->sh_size ) + goto bad_offset; + + val -= (uint64_t)dest; + *(int32_t *)dest = val; + if ( (int64_t)val != *(int32_t *)dest ) + { + dprintk(XENLOG_ERR, XSPLICE "%s: Overflow in relocation %u in %s for %s!\n", + elf->name, i, rela->name, base->name); + return -EOVERFLOW; + } + break; + + default: + dprintk(XENLOG_ERR, XSPLICE "%s: Unhandled relocation %lu\n", + elf->name, ELF64_R_TYPE(r->r_info)); + return -EOPNOTSUPP; + } + } + + return 0; + + bad_offset: + dprintk(XENLOG_ERR, XSPLICE "%s: Relative relocation offset is past %s section!\n", + elf->name, base->name); + return -EINVAL; +} + +/* + * 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(const void *va, unsigned int pages, enum va_type type) +{ + unsigned long start = (unsigned long)va; + unsigned int flag; + + ASSERT(va); + ASSERT(pages); + + if ( type == XSPLICE_VA_RX ) + flag = PAGE_HYPERVISOR_RX; + else if ( type == XSPLICE_VA_RW ) + flag = PAGE_HYPERVISOR_RW; + else + flag = PAGE_HYPERVISOR_RO; + + modify_xen_mappings(start, start + pages * PAGE_SIZE, flag); + + return 0; +} + +void __init 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 73e50f0..1688c6c 100644 --- a/xen/common/xsplice.c +++ b/xen/common/xsplice.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include @@ -29,6 +30,13 @@ 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'. */ + const void *text_addr; /* Virtual address of .text. */ + size_t text_size; /* .. and its size. */ + const void *rw_addr; /* Virtual address of .data. */ + size_t rw_size; /* .. and its size (if any). */ + const void *ro_addr; /* Virtual address of .rodata. */ + size_t ro_size; /* .. and its size (if any). */ + unsigned int pages; /* Total pages for [text,rw,ro]_addr */ char name[XEN_XSPLICE_NAME_SIZE]; /* Name of it. */ }; @@ -83,19 +91,223 @@ 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->pages ) + return; + + vfree((void *)payload->text_addr); + + payload->pages = 0; +} + +/* +* calc_section computes the size (taking into account section alignment). +* +* Furthermore the offset is set with the offset from the start of the virtual +* address space for the payload (using passed in size). This is used in +* move_payload to figure out the destination location (load_addr). +*/ +static void calc_section(const struct xsplice_elf_sec *sec, size_t *size, + unsigned int *offset) +{ + const Elf_Shdr *s = sec->sec; + size_t align_size; + + align_size = ROUNDUP(*size, s->sh_addralign); + *offset = align_size; + *size = s->sh_size + align_size; +} + +static int move_payload(struct payload *payload, struct xsplice_elf *elf) +{ + void *text_buf, *ro_buf, *rw_buf; + unsigned int i; + size_t size = 0; + unsigned int *offset; + int rc = 0; + + offset = xmalloc_array(unsigned int, elf->hdr->e_shnum); + if ( !offset ) + return -ENOMEM; + + /* Compute size of different regions. */ + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + /* + * Do nothing. These are .rel.text, rel.*, .symtab, .strtab, + * and .shstrtab. For the non-relocate we allocate and copy these + * via other means - and the .rel we can ignore as we only use it + * once during loading. + */ + if ( !(elf->sec[i].sec->sh_flags & SHF_ALLOC) ) + { + offset[i] = UINT_MAX; + continue; + } + if ( (elf->sec[i].sec->sh_flags & SHF_EXECINSTR) && + !(elf->sec[i].sec->sh_flags & SHF_WRITE) ) + calc_section(&elf->sec[i], &payload->text_size, &offset[i]); + else if ( !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) && + (elf->sec[i].sec->sh_flags & SHF_WRITE) ) + calc_section(&elf->sec[i], &payload->rw_size, &offset[i]); + else if ( !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) && + !(elf->sec[i].sec->sh_flags & SHF_WRITE) ) + calc_section(&elf->sec[i], &payload->ro_size, &offset[i]); + else + { + dprintk(XENLOG_DEBUG, XSPLICE "%s: Not supporting %s section!\n", + elf->name, elf->sec[i].name); + rc = -EOPNOTSUPP; + goto out; + } + } + + /* + * 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); /* Nr of pages. */ + text_buf = vmalloc_xen(size * PAGE_SIZE); + if ( !text_buf ) + { + dprintk(XENLOG_ERR, XSPLICE "%s: Could not allocate memory for payload!\n", + elf->name); + rc = -ENOMEM; + goto out; + } + rw_buf = text_buf + PAGE_ALIGN(payload->text_size); + ro_buf = rw_buf + PAGE_ALIGN(payload->rw_size); + + payload->pages = size; + payload->text_addr = text_buf; + payload->rw_addr = rw_buf; + payload->ro_addr = ro_buf; + + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + if ( elf->sec[i].sec->sh_flags & SHF_ALLOC ) + { + void *buf; + + if ( elf->sec[i].sec->sh_flags & SHF_EXECINSTR ) + buf = text_buf; + else if ( elf->sec[i].sec->sh_flags & SHF_WRITE ) + buf = rw_buf; + else + buf = ro_buf; + + ASSERT(offset[i] != UINT_MAX); + + elf->sec[i].load_addr = buf + offset[i]; + + /* 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 %p\n", + elf->name, elf->sec[i].name, elf->sec[i].load_addr); + } + else + memset(elf->sec[i].load_addr, 0, elf->sec[i].sec->sh_size); + } + } + + out: + xfree(offset); + + return rc; +} + +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, *found; char n[XEN_XSPLICE_NAME_SIZE]; + void *raw_data; int rc; rc = verify_payload(upload, n); @@ -103,6 +315,7 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload) return rc; data = xzalloc(struct payload); + raw_data = vmalloc(upload->size); spin_lock(&payload_lock); @@ -111,11 +324,18 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload) rc = PTR_ERR(found); else if ( found ) rc = -EEXIST; - else if ( !data ) + else if ( !data || !raw_data ) rc = -ENOMEM; + else if ( __copy_from_guest(raw_data, upload->payload, upload->size) ) + rc = -EFAULT; else { 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); @@ -123,8 +343,12 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload) payload_cnt++; payload_version++; } + + out: spin_unlock(&payload_lock); + vfree(raw_data); + if ( rc ) xfree(data); @@ -359,8 +583,9 @@ 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 %u pages.\n", + data->name, state2str(data->state), data->state, data->text_addr, + data->rw_addr, data->ro_addr, data->pages); spin_unlock(&payload_lock); } @@ -368,6 +593,8 @@ 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 f046015..f51a161 100644 --- a/xen/common/xsplice_elf.c +++ b/xen/common/xsplice_elf.c @@ -100,6 +100,7 @@ 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. @@ -250,9 +251,122 @@ 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; + + ASSERT(elf->sym); + + for ( i = 1; i < elf->nsym; i++ ) + { + unsigned int idx = elf->sym[i].sym->st_shndx; + const Elf_Sym *sym = elf->sym[i].sym; + Elf_Addr st_value = sym->st_value; + + switch ( idx ) + { + case SHN_COMMON: + dprintk(XENLOG_ERR, XSPLICE "%s: Unexpected common symbol: %s\n", + elf->name, elf->sym[i].name); + rc = -EINVAL; + break; + + case SHN_UNDEF: + dprintk(XENLOG_ERR, 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, sym->st_value); + break; + + default: + /* SHN_COMMON and SHN_ABS are above. */ + if ( idx >= SHN_LORESERVE ) + rc = -EOPNOTSUPP; + else if ( idx >= elf->hdr->e_shnum ) + rc = -EINVAL; + + if ( rc ) + { + dprintk(XENLOG_ERR, XSPLICE "%s: Out of bounds symbol section %#x\n", + elf->name, idx); + break; + } + + /* Matches 'move_payload' which ignores such sections. */ + if ( !(elf->sec[idx].sec->sh_flags & SHF_ALLOC) ) + break; + + st_value += (unsigned long)elf->sec[idx].load_addr; + if ( elf->sym[i].name ) + dprintk(XENLOG_DEBUG, XSPLICE "%s: Symbol resolved: %s => %#"PRIxElfAddr" (%s)\n", + elf->name, elf->sym[i].name, + st_value, elf->sec[idx].name); + } + + if ( rc ) + break; + + ((Elf_Sym *)sym)->st_value = st_value; + } + + return rc; +} + +int xsplice_elf_perform_relocs(struct xsplice_elf *elf) +{ + struct xsplice_elf_sec *r, *base; + unsigned int i; + int rc = 0; + + ASSERT(elf->sym); + + for ( i = 1; i < elf->hdr->e_shnum; i++ ) + { + r = &elf->sec[i]; + + if ( (r->sec->sh_type != SHT_RELA) && + (r->sec->sh_type != SHT_REL) ) + continue; + + /* Is it a valid relocation section? */ + if ( r->sec->sh_info >= elf->hdr->e_shnum ) + continue; + + base = &elf->sec[r->sec->sh_info]; + + /* Don't relocate non-allocated sections. */ + if ( !(base->sec->sh_flags & SHF_ALLOC) ) + continue; + + if ( r->sec->sh_link != elf->symtab_idx ) + { + dprintk(XENLOG_ERR, XSPLICE "%s: Relative link of %s is incorrect (%d, expected=%d)\n", + elf->name, r->name, r->sec->sh_link, elf->symtab_idx); + rc = -EINVAL; + break; + } + + if ( r->sec->sh_type == SHT_RELA ) + rc = arch_xsplice_perform_rela(elf, base, r); + else /* SHT_REL */ + rc = arch_xsplice_perform_rel(elf, base, r); + + 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 ) { @@ -279,6 +393,10 @@ 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_ERR, XSPLICE "%s: Section name idx is undefined!?\n", diff --git a/xen/include/xen/elfstructs.h b/xen/include/xen/elfstructs.h index 85f35ed..2b9bd3f 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 PRIx64 + #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 7559877..857c264 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 +18,27 @@ 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 */ +}; + +/* + * Function to secure the allocate pages (from arch_xsplice_alloc_payload) + * with the right page permissions. + */ +int arch_xsplice_secure(const void *va, unsigned int pages, enum va_type types); + +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 686aaf0..750dc94 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 *strtab;/* Pointer to .strtab section - aka to sec[y]. */ + 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. */ + 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__ */ /*