The extra memory allocated for carrying the IMA measurement list across kexec is hard-coded as half a PAGE. Make it configurable.
Define a Kconfig option, IMA_KEXEC_EXTRA_MEMORY_KB, to configure the extra memory (in kb) to be allocated for IMA measurements added during kexec soft reboot. Ensure the default value of the option is set such that extra half a page of memory for additional measurements is allocated for the additional measurements. Update ima_add_kexec_buffer() function to allocate memory based on the Kconfig option value, rather than the currently hard-coded one. Suggested-by: Stefan Berger <[email protected]> Reviewed-by: Stefan Berger <[email protected]> Signed-off-by: Tushar Sugandhi <[email protected]> --- security/integrity/ima/Kconfig | 9 +++++++++ security/integrity/ima/ima_kexec.c | 15 ++++++++++----- 2 files changed, 19 insertions(+), 5 deletions(-) diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index b98bfe9efd0c..4c0fc53d6aa3 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -320,4 +320,13 @@ config IMA_DISABLE_HTABLE help This option disables htable to allow measurement of duplicate records. +config IMA_KEXEC_EXTRA_MEMORY_KB + int + depends on IMA_KEXEC + default 0 + help + IMA_KEXEC_EXTRA_MEMORY_KB determines the extra memory to be + allocated (in kb) for IMA measurements added during kexec soft reboot. + If set to the default value, an extra half a page of memory for those + additional measurements will be allocated. endif diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index dbeeb7f1355e..50903d4ce880 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -126,6 +126,7 @@ void ima_add_kexec_buffer(struct kimage *image) .buf_min = 0, .buf_max = ULONG_MAX, .top_down = true }; unsigned long binary_runtime_size; + unsigned long extra_size; /* use more understandable variable names than defined in kbuf */ void *kexec_buffer = NULL; @@ -133,15 +134,19 @@ void ima_add_kexec_buffer(struct kimage *image) int ret; /* - * Reserve an extra half page of memory for additional measurements - * added during the kexec load. + * Reserve extra memory for measurements added during kexec. */ - binary_runtime_size = ima_get_binary_runtime_size(); + if (CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB <= 0) + extra_size = PAGE_SIZE / 2; + else + extra_size = CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024; + binary_runtime_size = ima_get_binary_runtime_size() + extra_size; + if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE) kexec_segment_size = ULONG_MAX; else - kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + - PAGE_SIZE / 2, PAGE_SIZE); + kexec_segment_size = ALIGN(binary_runtime_size, PAGE_SIZE); + if ((kexec_segment_size == ULONG_MAX) || ((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) { pr_err("Binary measurement list too large.\n"); -- 2.25.1
