From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758690AbcH3RqC (ORCPT ); Tue, 30 Aug 2016 13:46:02 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:41186 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758614AbcH3Rp5 (ORCPT ); Tue, 30 Aug 2016 13:45:57 -0400 X-IBM-Helo: d24dlp02.br.ibm.com X-IBM-MailFrom: bauerman@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org;linux-security-module@vger.kernel.org From: Thiago Jung Bauermann To: kexec@lists.infradead.org Cc: linux-security-module@vger.kernel.org, linux-ima-devel@lists.sourceforge.net, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Eric Biederman , Dave Young , Vivek Goyal , Baoquan He , Michael Ellerman , Stewart Smith , Mimi Zohar , Eric Richter , Andrew Morton , Balbir Singh , Thiago Jung Bauermann Subject: [PATCH v4 4/5] kexec_file: Add mechanism to update kexec segments. Date: Tue, 30 Aug 2016 14:45:04 -0300 X-Mailer: git-send-email 1.9.1 In-Reply-To: <1472579105-26296-1-git-send-email-bauerman@linux.vnet.ibm.com> References: <1472579105-26296-1-git-send-email-bauerman@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16083017-0032-0000-0000-0000027C702D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16083017-0033-0000-0000-00000EC7E432 Message-Id: <1472579105-26296-5-git-send-email-bauerman@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-08-30_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=13 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1608300169 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org kexec_update_segment allows a given segment in kexec_image to have its contents updated. This is useful if the current kernel wants to send information to the next kernel that is up-to-date at the time of reboot. Signed-off-by: Thiago Jung Bauermann --- include/linux/kexec.h | 2 ++ kernel/kexec_core.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 100 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index edadff6c86ff..ff3aa93649e2 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -256,6 +256,8 @@ extern int kexec_purgatory_get_set_symbol(struct kimage *image, unsigned int size, bool get_value); extern void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name); +int kexec_update_segment(const char *buffer, size_t bufsz, + unsigned long load_addr, size_t memsz); extern void __crash_kexec(struct pt_regs *); extern void crash_kexec(struct pt_regs *); int kexec_should_crash(struct task_struct *); diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 561675589511..d3f1ebf66222 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -721,6 +721,104 @@ static struct page *kimage_alloc_page(struct kimage *image, return page; } +/** + * kexec_update_segment - update the contents of a kimage segment + * @buffer: New contents of the segment. + * @bufsz: @buffer size. + * @load_addr: Segment's physical address in the next kernel. + * @memsz: Segment size. + * + * This function assumes kexec_mutex is held. + * + * Return: 0 on success, negative errno on error. + */ +int kexec_update_segment(const char *buffer, size_t bufsz, + unsigned long load_addr, size_t memsz) +{ + int i; + unsigned long entry; + unsigned long *ptr = NULL; + void *dest = NULL; + + if (kexec_image == NULL) { + pr_err("Can't update segment: no kexec image loaded.\n"); + return -EINVAL; + } + + /* + * kexec_add_buffer rounds up segment sizes to PAGE_SIZE, so + * we have to do it here as well. + */ + memsz = ALIGN(memsz, PAGE_SIZE); + + for (i = 0; i < kexec_image->nr_segments; i++) + /* We only support updating whole segments. */ + if (load_addr == kexec_image->segment[i].mem && + memsz == kexec_image->segment[i].memsz) { + if (!kexec_image->segment[i].skip_checksum) { + pr_err("Trying to update non-modifiable segment.\n"); + return -EINVAL; + } + + break; + } + if (i == kexec_image->nr_segments) { + pr_err("Couldn't find segment to update: 0x%lx, size 0x%zx\n", + load_addr, memsz); + return -EINVAL; + } + + for (entry = kexec_image->head; !(entry & IND_DONE) && memsz; + entry = *ptr++) { + void *addr = (void *) (entry & PAGE_MASK); + + switch (entry & IND_FLAGS) { + case IND_DESTINATION: + dest = addr; + break; + case IND_INDIRECTION: + ptr = __va(entry & PAGE_MASK); + break; + case IND_SOURCE: + /* Shouldn't happen, but verify just to be safe. */ + if (dest == NULL) { + pr_err("Invalid kexec entries list."); + return -EINVAL; + } + + if (dest == (void *) load_addr) { + void *page_addr; + unsigned long offset; + size_t uchunk, mchunk; + + page_addr = kmap_atomic(kmap_to_page(addr)); + + offset = load_addr & ~PAGE_MASK; + mchunk = min_t(size_t, memsz, + PAGE_SIZE - offset); + uchunk = min(bufsz, mchunk); + memcpy(page_addr + offset, buffer, uchunk); + + kunmap_atomic(page_addr); + + bufsz -= uchunk; + load_addr += mchunk; + buffer += mchunk; + memsz -= mchunk; + } + dest += PAGE_SIZE; + } + + /* Shouldn't happen, but verify just to be safe. */ + if (ptr == NULL) { + pr_err("Invalid kexec entries list."); + return -EINVAL; + } + } + + return 0; +} + static int kimage_load_normal_segment(struct kimage *image, struct kexec_segment *segment) { -- 1.9.1