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Wed, 19 Mar 2025 20:53:45 +0000 (GMT) Message-ID: Subject: Re: [PATCH v10 6/8] ima: kexec: move IMA log copy from kexec load to execute From: Mimi Zohar To: steven chen , stefanb@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 Date: Wed, 19 Mar 2025 16:53:44 -0400 In-Reply-To: <20250318010448.954-7-chenste@linux.microsoft.com> References: <20250318010448.954-1-chenste@linux.microsoft.com> <20250318010448.954-7-chenste@linux.microsoft.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.52.4 (3.52.4-2.fc40) Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: NSEznNJZwO53Fdc7avUwq61S5_BLCk4K X-Proofpoint-GUID: NSEznNJZwO53Fdc7avUwq61S5_BLCk4K X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-19_07,2025-03-19_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 bulkscore=0 spamscore=0 malwarescore=0 mlxlogscore=999 suspectscore=0 adultscore=0 priorityscore=1501 mlxscore=0 lowpriorityscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503190137 On Mon, 2025-03-17 at 18:04 -0700, steven chen wrote: > ima_dump_measurement_list() is called during kexec 'load', which may > result in loss of IMA measurements during kexec soft reboot. Due to=20 > missed measurements that only occurred after kexec 'load', this function= =20 > needs to be called during kexec 'execute'. -> , defer calling ima_dump_measurement_list() to kexec 'execute'. >=20 > 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. > - 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 so that it= =20 > becomes accessible both during kexec 'load' and 'execute'. > - Move ima_dump_measurement_list() call from ima_add_kexec_buffer() > to ima_update_kexec_buffer(). > - Copy the measurement list as much as possible. Let's summarize the above changes, as below, and then remove the list. Define and call the new kimage_file_post_load() to call ima_kexec_post_load= (), which registers the reboot notifier (ima_update_kexec_buffer). Finally, move ima_dump_measurement_list() from ima_add_kexec_buffer() to ima_update_kexec_buffer() to defer copying the measurement list. > - 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' would corrupt the buffer. Instead of adding and then removing the ima_reset_kexec_file() call from ima_add_kexec_buffer(), defer adding the test in ima_alloc_kexec_file_buf()= to see if the segment size has changed. That should be a subsequent patch, af= ter this one. ima_reset_kexec_file() is then ever called from only one place. Combine ima_reset_kexec_file() with ima_free_kexec_file_buf(). thanks, Mimi >=20 > Signed-off-by: Tushar Sugandhi > Cc: Eric Biederman > Cc: Baoquan He =20 > Cc: Vivek Goyal > Cc: Dave Young > Signed-off-by: steven chen > Reviewed-by: Stefan Berger > --- > kernel/kexec_file.c | 10 ++++++ > security/integrity/ima/ima_kexec.c | 51 ++++++++++++++++++------------ > 2 files changed, 40 insertions(+), 21 deletions(-) >=20 > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 606132253c79..ab449b43aaee 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -201,6 +201,13 @@ kimage_validate_signature(struct kimage *image) > } > #endif > =20 > +static void kimage_file_post_load(struct kimage *image) > +{ > +#ifdef CONFIG_IMA_KEXEC > + ima_kexec_post_load(image); > +#endif > +} > + > /* > * In file mode list of segments is prepared by kernel. Copy relevant > * data from user space, do error checking, prepare segment list > @@ -428,6 +435,9 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int,= initrd_fd, > =20 > kimage_terminate(image); > =20 > + if (!(flags & KEXEC_FILE_ON_CRASH)) > + kimage_file_post_load(image); > + > ret =3D 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 9336c4f60650..c390c745f882 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -19,6 +19,7 @@ > #ifdef CONFIG_IMA_KEXEC > static bool ima_kexec_update_registered; > static struct seq_file ima_kexec_file; > +static size_t kexec_segment_size; > static void *ima_kexec_buffer; > =20 > static void ima_reset_kexec_file(struct seq_file *sf) > @@ -67,7 +68,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size= ) > * if the size of the allocated memory is not less than the size of I= MA measurement list > * copy the measurement list to the allocated memory. > * else > - * return error > + * copy the measurement list as much as possible. > */ > static int ima_dump_measurement_list(unsigned long *buffer_size, void **= buffer, > unsigned long segment_size) > @@ -95,9 +96,6 @@ static int ima_dump_measurement_list(unsigned long *buf= fer_size, void **buffer, > } > } > =20 > - if (ret < 0) > - goto out; > - > /* > * fill in reserved space with some buffer details > * (eg. version, buffer size, number of measurements) > @@ -117,7 +115,7 @@ static int ima_dump_measurement_list(unsigned long *b= uffer_size, void **buffer, > =20 > *buffer_size =3D ima_kexec_file.count; > *buffer =3D ima_kexec_file.buf; > -out: > + > return ret; > } > =20 > @@ -135,9 +133,8 @@ void ima_add_kexec_buffer(struct kimage *image) > unsigned long binary_runtime_size; > =20 > /* use more understandable variable names than defined in kbuf */ > + size_t kexec_buffer_size =3D 0; > void *kexec_buffer =3D NULL; > - size_t kexec_buffer_size; > - size_t kexec_segment_size; > int ret; > =20 > /* > @@ -162,13 +159,6 @@ void ima_add_kexec_buffer(struct kimage *image) > return; > } > =20 > - ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, > - kexec_segment_size); > - if (!kexec_buffer) { > - pr_err("Not enough memory for the kexec measurement buffer.\n"); > - return; > - } > - > kbuf.buffer =3D kexec_buffer; > kbuf.bufsz =3D kexec_buffer_size; > kbuf.memsz =3D kexec_segment_size; > @@ -186,12 +176,6 @@ void ima_add_kexec_buffer(struct kimage *image) > image->ima_segment_index =3D image->nr_segments - 1; > image->is_ima_segment_index_set =3D true; > =20 > - /* > - * 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); > } > @@ -202,7 +186,32 @@ 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; > + size_t buf_size =3D 0; > + int ret =3D NOTIFY_OK; > + void *buf =3D NULL; > + > + 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 =3D ima_dump_measurement_list(&buf_size, &buf, kexec_segment_size); > + > + if (ret) > + pr_err("Dump measurements failed. Error:%d\n", ret); > + > + if (buf_size !=3D 0) > + memcpy(ima_kexec_buffer, buf, buf_size); > + > + kimage_unmap_segment(ima_kexec_buffer); > + ima_kexec_buffer =3D NULL; > + > + return ret; > } > =20 > static struct notifier_block update_buffer_nb =3D {