In the current IMA implementation, ima_dump_measurement_list() is called during the kexec 'load' operation. This can result in loss of IMA measurements taken between the 'load' and 'execute' phases when the system goes through Kexec soft reboot to a new Kernel. The call to the function ima_dump_measurement_list() needs to be moved out of the function ima_add_kexec_buffer() and needs to be called during the kexec 'execute' operation. Implement a function ima_update_kexec_buffer() that is called during kexec 'execute', allowing IMA to update the measurement list with the events between kexec 'load' and 'execute'. Move the ima_dump_measurement_list() call from ima_add_kexec_buffer() to ima_update_kexec_buffer(). Make ima_kexec_buffer and kexec_segment_size variables global, so that they can be accessed during both kexec 'load' and 'execute'. Add functions ima_measurements_suspend() and ima_measurements_resume() to set and reset the 'suspend_ima_measurements' variable respectively, to suspend/resume IMA measurements. Use the existing 'ima_extend_list_mutex' to ensure that the operations are thread-safe. These function calls will help maintaining the integrity of the IMA log while it is being copied to the new Kernel's buffer. Add a reboot notifier_block 'update_buffer_nb' to ensure the function ima_update_kexec_buffer() gets called during kexec soft-reboot. Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx> --- security/integrity/ima/ima.h | 2 ++ security/integrity/ima/ima_kexec.c | 58 +++++++++++++++++++++++++----- security/integrity/ima/ima_queue.c | 18 ++++++++++ 3 files changed, 69 insertions(+), 9 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index c29db699c996..49a6047dd8eb 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -161,6 +161,8 @@ bool ima_template_has_modsig(const struct ima_template_desc *ima_template); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); +void ima_measurements_suspend(void); +void ima_measurements_resume(void); unsigned long ima_get_binary_runtime_size(void); int ima_init_template(void); void ima_init_template_list(void); diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index 307e07991865..2c11bbe6efef 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -17,6 +17,8 @@ #ifdef CONFIG_IMA_KEXEC struct seq_file ima_kexec_file; struct ima_kexec_hdr ima_khdr; +static void *ima_kexec_buffer; +static size_t kexec_segment_size; void ima_clear_kexec_file(void) { @@ -142,7 +144,6 @@ 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; - size_t kexec_segment_size; int ret; /* @@ -167,14 +168,6 @@ 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("%s: Failed to dump IMA measurements. Error:%d.\n", - __func__, ret); - return; - } - kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; @@ -192,6 +185,53 @@ void ima_add_kexec_buffer(struct kimage *image) pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n", kbuf.mem); } + +/* + * Called during kexec execute so that IMA can update the measurement list. + */ +static int ima_update_kexec_buffer(struct notifier_block *self, + unsigned long action, void *data) +{ + void *buf = NULL; + size_t buf_size; + bool resume = false; + int ret; + + if (!kexec_in_progress) { + pr_info("%s: No kexec in progress.\n", __func__); + return NOTIFY_OK; + } + + if (!ima_kexec_buffer) { + pr_err("%s: Kexec buffer not set.\n", __func__); + return NOTIFY_OK; + } + + ima_measurements_suspend(); + + buf_size = ima_get_binary_runtime_size(); + ret = ima_dump_measurement_list(&buf_size, &buf, + kexec_segment_size); + + if (!buf || ret < 0) { + pr_err("%s: Dump measurements failed. Error:%d\n", + __func__, ret); + resume = true; + goto out; + } + memcpy(ima_kexec_buffer, buf, buf_size); +out: + ima_kexec_buffer = NULL; + + if (resume) + ima_measurements_resume(); + + return NOTIFY_OK; +} +struct notifier_block update_buffer_nb = { + .notifier_call = ima_update_kexec_buffer, +}; + #endif /* IMA_KEXEC */ /* diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c index 532da87ce519..9e7d1196006e 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -44,6 +44,11 @@ struct ima_h_table ima_htable = { */ static DEFINE_MUTEX(ima_extend_list_mutex); +/* + * Used internally by the kernel to suspend-resume ima measurements. + */ +static atomic_t suspend_ima_measurements; + /* lookup up the digest value in the hash table, and return the entry */ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value, int pcr) @@ -147,6 +152,19 @@ static int ima_pcr_extend(struct tpm_digest *digests_arg, int pcr) pr_err("Error Communicating to TPM chip, result: %d\n", result); return result; } +void ima_measurements_suspend(void) +{ + mutex_lock(&ima_extend_list_mutex); + atomic_set(&suspend_ima_measurements, 1); + mutex_unlock(&ima_extend_list_mutex); +} + +void ima_measurements_resume(void) +{ + mutex_lock(&ima_extend_list_mutex); + atomic_set(&suspend_ima_measurements, 0); + mutex_unlock(&ima_extend_list_mutex); +} /* * Add template entry to the measurement list and hash table, and -- 2.25.1 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec