/* SPDX-License-Identifier: GPL-2.0-only */ #include #include #include #include #include #include /* option_table.h is autogenerated */ #include "option_table.h" /* Don't warn for checking >= LB_CKS_RANGE_START even though it may be 0. */ #pragma GCC diagnostic ignored "-Wtype-limits" /* * This routine returns the value of the requested bits. * input bit = bit count from the beginning of the CMOS image * length = number of bits to include in the value * ret = a character pointer to where the value is to be returned * returns CB_SUCCESS = successful, cb_err code if an error occurred */ static enum cb_err get_cmos_value(unsigned long bit, unsigned long length, void *vret) { unsigned char *ret; unsigned long byte, byte_bit; unsigned long i; unsigned char uchar; /* * The table is checked when it is built to ensure all * values are valid. */ ret = vret; byte = bit / 8; /* find the byte where the data starts */ byte_bit = bit % 8; /* find the bit in the byte where the data starts */ if (length < 9) { /* one byte or less */ uchar = cmos_read(byte); /* load the byte */ uchar >>= byte_bit; /* shift the bits to byte align */ /* clear unspecified bits */ ret[0] = uchar & ((1 << length) - 1); } else { /* more than one byte so transfer the whole bytes */ for (i = 0; length; i++, length -= 8, byte++) { /* load the byte */ ret[i] = cmos_read(byte); } } return CB_SUCCESS; } static enum cb_err locate_cmos_layout(struct region_device *rdev) { uint32_t cbfs_type = CBFS_COMPONENT_CMOS_LAYOUT; MAYBE_STATIC_BSS struct cbfsf fh = {}; /* * In case VBOOT is enabled and this function is called from SMM, * we have multiple CMOS layout files and to locate them we'd need to * include VBOOT into SMM... * * Support only one CMOS layout in the 'COREBOOT' region for now. */ if (!region_device_sz(&(fh.data))) { if (cbfs_locate_file_in_region(&fh, "COREBOOT", "cmos_layout.bin", &cbfs_type)) { printk(BIOS_ERR, "RTC: cmos_layout.bin could not be found. " "Options are disabled\n"); return CB_CMOS_LAYOUT_NOT_FOUND; } } cbfs_file_data(rdev, &fh); return CB_SUCCESS; } enum cb_err cmos_get_option(void *dest, const char *name) { struct cmos_option_table *ct; struct region_device rdev; struct cmos_entries *ce; size_t namelen; int found = 0; /* Figure out how long name is */ namelen = strnlen(name, CMOS_MAX_NAME_LENGTH); if (locate_cmos_layout(&rdev) != CB_SUCCESS) { return CB_CMOS_LAYOUT_NOT_FOUND; } ct = rdev_mmap_full(&rdev); if (!ct) { printk(BIOS_ERR, "RTC: cmos_layout.bin could not be mapped. " "Options are disabled\n"); return CB_CMOS_LAYOUT_NOT_FOUND; } /* find the requested entry record */ ce = (struct cmos_entries *)((unsigned char *)ct + ct->header_length); for (; ce->tag == LB_TAG_OPTION; ce = (struct cmos_entries *)((unsigned char *)ce + ce->size)) { if (memcmp(ce->name, name, namelen) == 0) { found = 1; break; } } if (!found) { printk(BIOS_DEBUG, "No CMOS option '%s'.\n", name); rdev_munmap(&rdev, ct); return CB_CMOS_OPTION_NOT_FOUND; } if (!cmos_checksum_valid(LB_CKS_RANGE_START, LB_CKS_RANGE_END, LB_CKS_LOC)) { rdev_munmap(&rdev, ct); return CB_CMOS_CHECKSUM_INVALID; } if (get_cmos_value(ce->bit, ce->length, dest) != CB_SUCCESS) { rdev_munmap(&rdev, ct); return CB_CMOS_ACCESS_ERROR; } rdev_munmap(&rdev, ct); return CB_SUCCESS; } static enum cb_err set_cmos_value(unsigned long bit, unsigned long length, void *vret) { unsigned char *ret; unsigned long byte, byte_bit; unsigned long i; unsigned char uchar, mask; unsigned int chksum_update_needed = 0; ret = vret; byte = bit / 8; /* find the byte where the data starts */ byte_bit = bit % 8; /* find the bit where the data starts */ if (length <= 8) { /* one byte or less */ mask = (1 << length) - 1; mask <<= byte_bit; uchar = cmos_read(byte); uchar &= ~mask; uchar |= (ret[0] << byte_bit); cmos_write(uchar, byte); if (byte >= LB_CKS_RANGE_START && byte <= LB_CKS_RANGE_END) chksum_update_needed = 1; } else { /* more that one byte so transfer the whole bytes */ if (byte_bit || length % 8) return CB_ERR_ARG; for (i = 0; length; i++, length -= 8, byte++) { cmos_write(ret[i], byte); if (byte >= LB_CKS_RANGE_START && byte <= LB_CKS_RANGE_END) chksum_update_needed = 1; } } if (chksum_update_needed) { cmos_set_checksum(LB_CKS_RANGE_START, LB_CKS_RANGE_END, LB_CKS_LOC); } return CB_SUCCESS; } enum cb_err cmos_set_option(const char *name, void *value) { struct cmos_option_table *ct; struct region_device rdev; struct cmos_entries *ce; unsigned long length; size_t namelen; int found = 0; /* Figure out how long name is */ namelen = strnlen(name, CMOS_MAX_NAME_LENGTH); if (locate_cmos_layout(&rdev) != CB_SUCCESS) { return CB_CMOS_LAYOUT_NOT_FOUND; } ct = rdev_mmap_full(&rdev); if (!ct) { printk(BIOS_ERR, "RTC: cmos_layout.bin could not be mapped. " "Options are disabled\n"); return CB_CMOS_LAYOUT_NOT_FOUND; } /* find the requested entry record */ ce = (struct cmos_entries *)((unsigned char *)ct + ct->header_length); for (; ce->tag == LB_TAG_OPTION; ce = (struct cmos_entries *)((unsigned char *)ce + ce->size)) { if (memcmp(ce->name, name, namelen) == 0) { found = 1; break; } } if (!found) { printk(BIOS_DEBUG, "WARNING: No CMOS option '%s'.\n", name); rdev_munmap(&rdev, ct); return CB_CMOS_OPTION_NOT_FOUND; } length = ce->length; if (ce->config == 's') { length = MAX(strlen((const char *)value) * 8, ce->length - 8); /* make sure the string is null terminated */ if (set_cmos_value(ce->bit + ce->length - 8, 8, &(u8[]){0}) != CB_SUCCESS) { rdev_munmap(&rdev, ct); return CB_CMOS_ACCESS_ERROR; } } if (set_cmos_value(ce->bit, length, value) != CB_SUCCESS) { rdev_munmap(&rdev, ct); return CB_CMOS_ACCESS_ERROR; } rdev_munmap(&rdev, ct); return CB_SUCCESS; } int cmos_lb_cks_valid(void) { return cmos_checksum_valid(LB_CKS_RANGE_START, LB_CKS_RANGE_END, LB_CKS_LOC); } void sanitize_cmos(void) { const unsigned char *cmos_default; const bool cmos_need_reset = CONFIG(STATIC_OPTION_TABLE) || cmos_error() || !cmos_lb_cks_valid(); size_t length = 128; size_t i; if (CONFIG(TPM_MEASURED_BOOT) || cmos_need_reset) { cmos_default = cbfs_boot_map_with_leak("cmos.default", CBFS_COMPONENT_CMOS_DEFAULT, &length); if (!cmos_default || !cmos_need_reset) return; u8 control_state = cmos_disable_rtc(); for (i = 14; i < MIN(128, length); i++) cmos_write_inner(cmos_default[i], i); cmos_restore_rtc(control_state); } }