diff options
Diffstat (limited to 'arch/x86/kernel/cpu/sgx/ioctl.c')
-rw-r--r-- | arch/x86/kernel/cpu/sgx/ioctl.c | 644 |
1 files changed, 601 insertions, 43 deletions
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 83df20e3e633..da8b8ea6b063 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -17,7 +17,7 @@ #include "encl.h" #include "encls.h" -static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl) +struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim) { struct sgx_va_page *va_page = NULL; void *err; @@ -30,7 +30,7 @@ static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl) if (!va_page) return ERR_PTR(-ENOMEM); - va_page->epc_page = sgx_alloc_va_page(); + va_page->epc_page = sgx_alloc_va_page(reclaim); if (IS_ERR(va_page->epc_page)) { err = ERR_CAST(va_page->epc_page); kfree(va_page); @@ -43,7 +43,7 @@ static struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl) return va_page; } -static void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page) +void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page) { encl->page_cnt--; @@ -64,7 +64,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) struct file *backing; long ret; - va_page = sgx_encl_grow(encl); + va_page = sgx_encl_grow(encl, true); if (IS_ERR(va_page)) return PTR_ERR(va_page); else if (va_page) @@ -107,6 +107,7 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) set_bit(SGX_ENCL_DEBUG, &encl->flags); encl->secs.encl = encl; + encl->secs.type = SGX_PAGE_TYPE_SECS; encl->base = secs->base; encl->size = secs->size; encl->attributes = secs->attributes; @@ -168,38 +169,6 @@ static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg) return ret; } -static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl, - unsigned long offset, - u64 secinfo_flags) -{ - struct sgx_encl_page *encl_page; - unsigned long prot; - - encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL); - if (!encl_page) - return ERR_PTR(-ENOMEM); - - encl_page->desc = encl->base + offset; - encl_page->encl = encl; - - prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ) | - _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) | - _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC); - - /* - * TCS pages must always RW set for CPU access while the SECINFO - * permissions are *always* zero - the CPU ignores the user provided - * values and silently overwrites them with zero permissions. - */ - if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS) - prot |= PROT_READ | PROT_WRITE; - - /* Calculate maximum of the VM flags for the page. */ - encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0); - - return encl_page; -} - static int sgx_validate_secinfo(struct sgx_secinfo *secinfo) { u64 perm = secinfo->flags & SGX_SECINFO_PERMISSION_MASK; @@ -306,7 +275,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, return PTR_ERR(epc_page); } - va_page = sgx_encl_grow(encl); + va_page = sgx_encl_grow(encl, true); if (IS_ERR(va_page)) { ret = PTR_ERR(va_page); goto err_out_free; @@ -344,6 +313,7 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src, */ encl_page->encl = encl; encl_page->epc_page = epc_page; + encl_page->type = (secinfo->flags & SGX_SECINFO_PAGE_TYPE_MASK) >> 8; encl->secs_child_cnt++; if (flags & SGX_PAGE_MEASURE) { @@ -372,6 +342,29 @@ err_out_free: return ret; } +/* + * Ensure user provided offset and length values are valid for + * an enclave. + */ +static int sgx_validate_offset_length(struct sgx_encl *encl, + unsigned long offset, + unsigned long length) +{ + if (!IS_ALIGNED(offset, PAGE_SIZE)) + return -EINVAL; + + if (!length || !IS_ALIGNED(length, PAGE_SIZE)) + return -EINVAL; + + if (offset + length < offset) + return -EINVAL; + + if (offset + length - PAGE_SIZE >= encl->size) + return -EINVAL; + + return 0; +} + /** * sgx_ioc_enclave_add_pages() - The handler for %SGX_IOC_ENCLAVE_ADD_PAGES * @encl: an enclave pointer @@ -425,14 +418,10 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg) if (copy_from_user(&add_arg, arg, sizeof(add_arg))) return -EFAULT; - if (!IS_ALIGNED(add_arg.offset, PAGE_SIZE) || - !IS_ALIGNED(add_arg.src, PAGE_SIZE)) - return -EINVAL; - - if (!add_arg.length || add_arg.length & (PAGE_SIZE - 1)) + if (!IS_ALIGNED(add_arg.src, PAGE_SIZE)) return -EINVAL; - if (add_arg.offset + add_arg.length - PAGE_SIZE >= encl->size) + if (sgx_validate_offset_length(encl, add_arg.offset, add_arg.length)) return -EINVAL; if (copy_from_user(&secinfo, (void __user *)add_arg.secinfo, @@ -674,6 +663,565 @@ static long sgx_ioc_enclave_provision(struct sgx_encl *encl, void __user *arg) return sgx_set_attribute(&encl->attributes_mask, params.fd); } +/* + * Ensure enclave is ready for SGX2 functions. Readiness is checked + * by ensuring the hardware supports SGX2 and the enclave is initialized + * and thus able to handle requests to modify pages within it. + */ +static int sgx_ioc_sgx2_ready(struct sgx_encl *encl) +{ + if (!(cpu_feature_enabled(X86_FEATURE_SGX2))) + return -ENODEV; + + if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) + return -EINVAL; + + return 0; +} + +/* + * Some SGX functions require that no cached linear-to-physical address + * mappings are present before they can succeed. Collaborate with + * hardware via ENCLS[ETRACK] to ensure that all cached + * linear-to-physical address mappings belonging to all threads of + * the enclave are cleared. See sgx_encl_cpumask() for details. + * + * Must be called with enclave's mutex held from the time the + * SGX function requiring that no cached linear-to-physical mappings + * are present is executed until this ETRACK flow is complete. + */ +static int sgx_enclave_etrack(struct sgx_encl *encl) +{ + void *epc_virt; + int ret; + + epc_virt = sgx_get_epc_virt_addr(encl->secs.epc_page); + ret = __etrack(epc_virt); + if (ret) { + /* + * ETRACK only fails when there is an OS issue. For + * example, two consecutive ETRACK was sent without + * completed IPI between. + */ + pr_err_once("ETRACK returned %d (0x%x)", ret, ret); + /* + * Send IPIs to kick CPUs out of the enclave and + * try ETRACK again. + */ + on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1); + ret = __etrack(epc_virt); + if (ret) { + pr_err_once("ETRACK repeat returned %d (0x%x)", + ret, ret); + return -EFAULT; + } + } + on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1); + + return 0; +} + +/** + * sgx_enclave_restrict_permissions() - Restrict EPCM permissions + * @encl: Enclave to which the pages belong. + * @modp: Checked parameters from user on which pages need modifying and + * their new permissions. + * + * Return: + * - 0: Success. + * - -errno: Otherwise. + */ +static long +sgx_enclave_restrict_permissions(struct sgx_encl *encl, + struct sgx_enclave_restrict_permissions *modp) +{ + struct sgx_encl_page *entry; + struct sgx_secinfo secinfo; + unsigned long addr; + unsigned long c; + void *epc_virt; + int ret; + + memset(&secinfo, 0, sizeof(secinfo)); + secinfo.flags = modp->permissions & SGX_SECINFO_PERMISSION_MASK; + + for (c = 0 ; c < modp->length; c += PAGE_SIZE) { + addr = encl->base + modp->offset + c; + + sgx_reclaim_direct(); + + mutex_lock(&encl->lock); + + entry = sgx_encl_load_page(encl, addr); + if (IS_ERR(entry)) { + ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT; + goto out_unlock; + } + + /* + * Changing EPCM permissions is only supported on regular + * SGX pages. Attempting this change on other pages will + * result in #PF. + */ + if (entry->type != SGX_PAGE_TYPE_REG) { + ret = -EINVAL; + goto out_unlock; + } + + /* + * Apart from ensuring that read-access remains, do not verify + * the permission bits requested. Kernel has no control over + * how EPCM permissions can be relaxed from within the enclave. + * ENCLS[EMODPR] can only remove existing EPCM permissions, + * attempting to set new permissions will be ignored by the + * hardware. + */ + + /* Change EPCM permissions. */ + epc_virt = sgx_get_epc_virt_addr(entry->epc_page); + ret = __emodpr(&secinfo, epc_virt); + if (encls_faulted(ret)) { + /* + * All possible faults should be avoidable: + * parameters have been checked, will only change + * permissions of a regular page, and no concurrent + * SGX1/SGX2 ENCLS instructions since these + * are protected with mutex. + */ + pr_err_once("EMODPR encountered exception %d\n", + ENCLS_TRAPNR(ret)); + ret = -EFAULT; + goto out_unlock; + } + if (encls_failed(ret)) { + modp->result = ret; + ret = -EFAULT; + goto out_unlock; + } + + ret = sgx_enclave_etrack(encl); + if (ret) { + ret = -EFAULT; + goto out_unlock; + } + + mutex_unlock(&encl->lock); + } + + ret = 0; + goto out; + +out_unlock: + mutex_unlock(&encl->lock); +out: + modp->count = c; + + return ret; +} + +/** + * sgx_ioc_enclave_restrict_permissions() - handler for + * %SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS + * @encl: an enclave pointer + * @arg: userspace pointer to a &struct sgx_enclave_restrict_permissions + * instance + * + * SGX2 distinguishes between relaxing and restricting the enclave page + * permissions maintained by the hardware (EPCM permissions) of pages + * belonging to an initialized enclave (after SGX_IOC_ENCLAVE_INIT). + * + * EPCM permissions cannot be restricted from within the enclave, the enclave + * requires the kernel to run the privileged level 0 instructions ENCLS[EMODPR] + * and ENCLS[ETRACK]. An attempt to relax EPCM permissions with this call + * will be ignored by the hardware. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl, + void __user *arg) +{ + struct sgx_enclave_restrict_permissions params; + long ret; + + ret = sgx_ioc_sgx2_ready(encl); + if (ret) + return ret; + + if (copy_from_user(¶ms, arg, sizeof(params))) + return -EFAULT; + + if (sgx_validate_offset_length(encl, params.offset, params.length)) + return -EINVAL; + + if (params.permissions & ~SGX_SECINFO_PERMISSION_MASK) + return -EINVAL; + + /* + * Fail early if invalid permissions requested to prevent ENCLS[EMODPR] + * from faulting later when the CPU does the same check. + */ + if ((params.permissions & SGX_SECINFO_W) && + !(params.permissions & SGX_SECINFO_R)) + return -EINVAL; + + if (params.result || params.count) + return -EINVAL; + + ret = sgx_enclave_restrict_permissions(encl, ¶ms); + + if (copy_to_user(arg, ¶ms, sizeof(params))) + return -EFAULT; + + return ret; +} + +/** + * sgx_enclave_modify_types() - Modify type of SGX enclave pages + * @encl: Enclave to which the pages belong. + * @modt: Checked parameters from user about which pages need modifying + * and their new page type. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_enclave_modify_types(struct sgx_encl *encl, + struct sgx_enclave_modify_types *modt) +{ + unsigned long max_prot_restore; + enum sgx_page_type page_type; + struct sgx_encl_page *entry; + struct sgx_secinfo secinfo; + unsigned long prot; + unsigned long addr; + unsigned long c; + void *epc_virt; + int ret; + + page_type = modt->page_type & SGX_PAGE_TYPE_MASK; + + /* + * The only new page types allowed by hardware are PT_TCS and PT_TRIM. + */ + if (page_type != SGX_PAGE_TYPE_TCS && page_type != SGX_PAGE_TYPE_TRIM) + return -EINVAL; + + memset(&secinfo, 0, sizeof(secinfo)); + + secinfo.flags = page_type << 8; + + for (c = 0 ; c < modt->length; c += PAGE_SIZE) { + addr = encl->base + modt->offset + c; + + sgx_reclaim_direct(); + + mutex_lock(&encl->lock); + + entry = sgx_encl_load_page(encl, addr); + if (IS_ERR(entry)) { + ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT; + goto out_unlock; + } + + /* + * Borrow the logic from the Intel SDM. Regular pages + * (SGX_PAGE_TYPE_REG) can change type to SGX_PAGE_TYPE_TCS + * or SGX_PAGE_TYPE_TRIM but TCS pages can only be trimmed. + * CET pages not supported yet. + */ + if (!(entry->type == SGX_PAGE_TYPE_REG || + (entry->type == SGX_PAGE_TYPE_TCS && + page_type == SGX_PAGE_TYPE_TRIM))) { + ret = -EINVAL; + goto out_unlock; + } + + max_prot_restore = entry->vm_max_prot_bits; + + /* + * Once a regular page becomes a TCS page it cannot be + * changed back. So the maximum allowed protection reflects + * the TCS page that is always RW from kernel perspective but + * will be inaccessible from within enclave. Before doing + * so, do make sure that the new page type continues to + * respect the originally vetted page permissions. + */ + if (entry->type == SGX_PAGE_TYPE_REG && + page_type == SGX_PAGE_TYPE_TCS) { + if (~entry->vm_max_prot_bits & (VM_READ | VM_WRITE)) { + ret = -EPERM; + goto out_unlock; + } + prot = PROT_READ | PROT_WRITE; + entry->vm_max_prot_bits = calc_vm_prot_bits(prot, 0); + + /* + * Prevent page from being reclaimed while mutex + * is released. + */ + if (sgx_unmark_page_reclaimable(entry->epc_page)) { + ret = -EAGAIN; + goto out_entry_changed; + } + + /* + * Do not keep encl->lock because of dependency on + * mmap_lock acquired in sgx_zap_enclave_ptes(). + */ + mutex_unlock(&encl->lock); + + sgx_zap_enclave_ptes(encl, addr); + + mutex_lock(&encl->lock); + + sgx_mark_page_reclaimable(entry->epc_page); + } + + /* Change EPC type */ + epc_virt = sgx_get_epc_virt_addr(entry->epc_page); + ret = __emodt(&secinfo, epc_virt); + if (encls_faulted(ret)) { + /* + * All possible faults should be avoidable: + * parameters have been checked, will only change + * valid page types, and no concurrent + * SGX1/SGX2 ENCLS instructions since these are + * protected with mutex. + */ + pr_err_once("EMODT encountered exception %d\n", + ENCLS_TRAPNR(ret)); + ret = -EFAULT; + goto out_entry_changed; + } + if (encls_failed(ret)) { + modt->result = ret; + ret = -EFAULT; + goto out_entry_changed; + } + + ret = sgx_enclave_etrack(encl); + if (ret) { + ret = -EFAULT; + goto out_unlock; + } + + entry->type = page_type; + + mutex_unlock(&encl->lock); + } + + ret = 0; + goto out; + +out_entry_changed: + entry->vm_max_prot_bits = max_prot_restore; +out_unlock: + mutex_unlock(&encl->lock); +out: + modt->count = c; + + return ret; +} + +/** + * sgx_ioc_enclave_modify_types() - handler for %SGX_IOC_ENCLAVE_MODIFY_TYPES + * @encl: an enclave pointer + * @arg: userspace pointer to a &struct sgx_enclave_modify_types instance + * + * Ability to change the enclave page type supports the following use cases: + * + * * It is possible to add TCS pages to an enclave by changing the type of + * regular pages (%SGX_PAGE_TYPE_REG) to TCS (%SGX_PAGE_TYPE_TCS) pages. + * With this support the number of threads supported by an initialized + * enclave can be increased dynamically. + * + * * Regular or TCS pages can dynamically be removed from an initialized + * enclave by changing the page type to %SGX_PAGE_TYPE_TRIM. Changing the + * page type to %SGX_PAGE_TYPE_TRIM marks the page for removal with actual + * removal done by handler of %SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl() called + * after ENCLU[EACCEPT] is run on %SGX_PAGE_TYPE_TRIM page from within the + * enclave. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_ioc_enclave_modify_types(struct sgx_encl *encl, + void __user *arg) +{ + struct sgx_enclave_modify_types params; + long ret; + + ret = sgx_ioc_sgx2_ready(encl); + if (ret) + return ret; + + if (copy_from_user(¶ms, arg, sizeof(params))) + return -EFAULT; + + if (sgx_validate_offset_length(encl, params.offset, params.length)) + return -EINVAL; + + if (params.page_type & ~SGX_PAGE_TYPE_MASK) + return -EINVAL; + + if (params.result || params.count) + return -EINVAL; + + ret = sgx_enclave_modify_types(encl, ¶ms); + + if (copy_to_user(arg, ¶ms, sizeof(params))) + return -EFAULT; + + return ret; +} + +/** + * sgx_encl_remove_pages() - Remove trimmed pages from SGX enclave + * @encl: Enclave to which the pages belong + * @params: Checked parameters from user on which pages need to be removed + * + * Return: + * - 0: Success. + * - -errno: Otherwise. + */ +static long sgx_encl_remove_pages(struct sgx_encl *encl, + struct sgx_enclave_remove_pages *params) +{ + struct sgx_encl_page *entry; + struct sgx_secinfo secinfo; + unsigned long addr; + unsigned long c; + void *epc_virt; + int ret; + + memset(&secinfo, 0, sizeof(secinfo)); + secinfo.flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X; + + for (c = 0 ; c < params->length; c += PAGE_SIZE) { + addr = encl->base + params->offset + c; + + sgx_reclaim_direct(); + + mutex_lock(&encl->lock); + + entry = sgx_encl_load_page(encl, addr); + if (IS_ERR(entry)) { + ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT; + goto out_unlock; + } + + if (entry->type != SGX_PAGE_TYPE_TRIM) { + ret = -EPERM; + goto out_unlock; + } + + /* + * ENCLS[EMODPR] is a no-op instruction used to inform if + * ENCLU[EACCEPT] was run from within the enclave. If + * ENCLS[EMODPR] is run with RWX on a trimmed page that is + * not yet accepted then it will return + * %SGX_PAGE_NOT_MODIFIABLE, after the trimmed page is + * accepted the instruction will encounter a page fault. + */ + epc_virt = sgx_get_epc_virt_addr(entry->epc_page); + ret = __emodpr(&secinfo, epc_virt); + if (!encls_faulted(ret) || ENCLS_TRAPNR(ret) != X86_TRAP_PF) { + ret = -EPERM; + goto out_unlock; + } + + if (sgx_unmark_page_reclaimable(entry->epc_page)) { + ret = -EBUSY; + goto out_unlock; + } + + /* + * Do not keep encl->lock because of dependency on + * mmap_lock acquired in sgx_zap_enclave_ptes(). + */ + mutex_unlock(&encl->lock); + + sgx_zap_enclave_ptes(encl, addr); + + mutex_lock(&encl->lock); + + sgx_encl_free_epc_page(entry->epc_page); + encl->secs_child_cnt--; + entry->epc_page = NULL; + xa_erase(&encl->page_array, PFN_DOWN(entry->desc)); + sgx_encl_shrink(encl, NULL); + kfree(entry); + + mutex_unlock(&encl->lock); + } + + ret = 0; + goto out; + +out_unlock: + mutex_unlock(&encl->lock); +out: + params->count = c; + + return ret; +} + +/** + * sgx_ioc_enclave_remove_pages() - handler for %SGX_IOC_ENCLAVE_REMOVE_PAGES + * @encl: an enclave pointer + * @arg: userspace pointer to &struct sgx_enclave_remove_pages instance + * + * Final step of the flow removing pages from an initialized enclave. The + * complete flow is: + * + * 1) User changes the type of the pages to be removed to %SGX_PAGE_TYPE_TRIM + * using the %SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl(). + * 2) User approves the page removal by running ENCLU[EACCEPT] from within + * the enclave. + * 3) User initiates actual page removal using the + * %SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl() that is handled here. + * + * First remove any page table entries pointing to the page and then proceed + * with the actual removal of the enclave page and data in support of it. + * + * VA pages are not affected by this removal. It is thus possible that the + * enclave may end up with more VA pages than needed to support all its + * pages. + * + * Return: + * - 0: Success + * - -errno: Otherwise + */ +static long sgx_ioc_enclave_remove_pages(struct sgx_encl *encl, + void __user *arg) +{ + struct sgx_enclave_remove_pages params; + long ret; + + ret = sgx_ioc_sgx2_ready(encl); + if (ret) + return ret; + + if (copy_from_user(¶ms, arg, sizeof(params))) + return -EFAULT; + + if (sgx_validate_offset_length(encl, params.offset, params.length)) + return -EINVAL; + + if (params.count) + return -EINVAL; + + ret = sgx_encl_remove_pages(encl, ¶ms); + + if (copy_to_user(arg, ¶ms, sizeof(params))) + return -EFAULT; + + return ret; +} + long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) { struct sgx_encl *encl = filep->private_data; @@ -695,6 +1243,16 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) case SGX_IOC_ENCLAVE_PROVISION: ret = sgx_ioc_enclave_provision(encl, (void __user *)arg); break; + case SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS: + ret = sgx_ioc_enclave_restrict_permissions(encl, + (void __user *)arg); + break; + case SGX_IOC_ENCLAVE_MODIFY_TYPES: + ret = sgx_ioc_enclave_modify_types(encl, (void __user *)arg); + break; + case SGX_IOC_ENCLAVE_REMOVE_PAGES: + ret = sgx_ioc_enclave_remove_pages(encl, (void __user *)arg); + break; default: ret = -ENOIOCTLCMD; break; |