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Wed, 19 Feb 2025 15:57:13 +0000 (GMT) Message-ID: <7433b986-f048-494d-a66a-5888cd37b081@linux.ibm.com> Date: Wed, 19 Feb 2025 10:57:13 -0500 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 5/7] ima: kexec: move IMA log copy from kexec load to execute To: steven chen , zohar@linux.ibm.com, roberto.sassu@huaweicloud.com, roberto.sassu@huawei.com, eric.snowberg@oracle.com, ebiederm@xmission.com, paul@paul-moore.com, code@tyhicks.com, bauermann@kolabnow.com, linux-integrity@vger.kernel.org, kexec@lists.infradead.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Cc: madvenka@linux.microsoft.com, nramas@linux.microsoft.com, James.Bottomley@HansenPartnership.com, bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com References: <20250218225502.747963-1-chenste@linux.microsoft.com> <20250218225502.747963-6-chenste@linux.microsoft.com> Content-Language: en-US From: Stefan Berger In-Reply-To: <20250218225502.747963-6-chenste@linux.microsoft.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: fIeIYbbJTYuYoV9uVtLxM_3bePvUUM8D X-Proofpoint-GUID: fIeIYbbJTYuYoV9uVtLxM_3bePvUUM8D X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-19_06,2025-02-19_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 impostorscore=0 suspectscore=0 mlxscore=0 clxscore=1015 bulkscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2502190122 On 2/18/25 5:55 PM, steven chen wrote: > ima_dump_measurement_list() is called during kexec 'load', which may > result in loss of IMA measurements during kexec soft reboot. It needs ... due to missed measurements that only occurred after kexec 'load'. Therefore, this function needs to be ... > to be called during kexec 'execute'. > > This patch includes the following changes: > - Implement kimage_file_post_load() function to be invoked after the new > Kernel image has been loaded for kexec. s/Kernel/kernel > - Call kimage_file_post_load() from kexec_file_load() syscall only for > kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH. It will > map the IMA segment, and register reboot notifier for the function > ima_update_kexec_buffer() which would copy the IMA log at kexec soft > reboot. > - Make kexec_segment_size variable local static to the file, for it to be ... to the file so that it becomes accessible ... > accessible both during kexec 'load' and 'execute'. > - Move ima_dump_measurement_list() call from ima_add_kexec_buffer() > to ima_update_kexec_buffer(). > - Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now > that the buffer is being copied at kexec 'execute', and resetting the > file at kexec 'load' will corrupt the buffer. s/will/would > > Signed-off-by: Tushar Sugandhi > Signed-off-by: steven chen With the above changes: Reviewed-by: Stefan Berger > --- > kernel/kexec_file.c | 8 ++++++ > security/integrity/ima/ima_kexec.c | 43 +++++++++++++++++++----------- > 2 files changed, 36 insertions(+), 15 deletions(-) > > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 606132253c79..76b6a877b842 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -201,6 +201,11 @@ kimage_validate_signature(struct kimage *image) > } > #endif > > +static void kimage_file_post_load(struct kimage *image) > +{ > + ima_kexec_post_load(image); > +} > + > /* > * In file mode list of segments is prepared by kernel. Copy relevant > * data from user space, do error checking, prepare segment list > @@ -428,6 +433,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, > > kimage_terminate(image); > > + if (!(flags & KEXEC_FILE_ON_CRASH)) > + kimage_file_post_load(image); > + > ret = machine_kexec_post_load(image); > if (ret) > goto out; > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index 0fa65f91414b..f9dd7ff95b84 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -19,6 +19,7 @@ > #ifdef CONFIG_IMA_KEXEC > static struct seq_file ima_kexec_file; > static void *ima_kexec_buffer; > +static size_t kexec_segment_size; > static bool ima_kexec_update_registered; > > static void ima_reset_kexec_file(struct seq_file *sf) > @@ -129,7 +130,6 @@ void ima_add_kexec_buffer(struct kimage *image) > /* use more understandable variable names than defined in kbuf */ > void *kexec_buffer = NULL; > size_t kexec_buffer_size = 0; > - size_t kexec_segment_size; > int ret; > > /* > @@ -154,13 +154,6 @@ void ima_add_kexec_buffer(struct kimage *image) > return; > } > > - ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, > - kexec_segment_size); > - if (ret < 0) { > - pr_err("Failed to dump IMA measurements. Error:%d.\n", ret); > - return; > - } > - > kbuf.buffer = kexec_buffer; > kbuf.bufsz = kexec_buffer_size; > kbuf.memsz = kexec_segment_size; > @@ -178,12 +171,6 @@ void ima_add_kexec_buffer(struct kimage *image) > image->ima_segment_index = image->nr_segments - 1; > image->is_ima_segment_index_set = true; > > - /* > - * kexec owns kexec_buffer after kexec_add_buffer() is called > - * and it will vfree() that buffer. > - */ > - ima_reset_kexec_file(&ima_kexec_file); > - > kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n", > kbuf.mem); > } > @@ -194,7 +181,33 @@ void ima_add_kexec_buffer(struct kimage *image) > static int ima_update_kexec_buffer(struct notifier_block *self, > unsigned long action, void *data) > { > - return NOTIFY_OK; > + void *buf = NULL; > + size_t buf_size = 0; > + int ret = NOTIFY_OK; > + > + if (!kexec_in_progress) { > + pr_info("No kexec in progress.\n"); > + return ret; > + } > + > + if (!ima_kexec_buffer) { > + pr_err("Kexec buffer not set.\n"); > + return ret; > + } > + > + ret = ima_dump_measurement_list(&buf_size, &buf, > + kexec_segment_size); > + > + if (ret) > + pr_err("Dump measurements failed. Error:%d\n", ret); > + > + if (buf_size != 0) > + memcpy(ima_kexec_buffer, buf, buf_size); > + > + kimage_unmap_segment(ima_kexec_buffer); > + ima_kexec_buffer = NULL; > + > + return ret; > } > > struct notifier_block update_buffer_nb = {