| Message ID | 20181125151500.8298-5-nayna@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | add platform/firmware keys support for kernel verification by IMA | expand |
On Sun, 2018-11-25 at 20:44 +0530, Nayna Jain wrote: > From: Dave Howells <dhowells@redhat.com> > > Add a function to parse an EFI signature blob looking for elements of > interest. A list is made up of a series of sublists, where all the > elements in a sublist are of the same type, but sublists can be of > different types. > > For each sublist encountered, the function pointed to by the > get_handler_for_guid argument is called with the type specifier GUID and > returns either a pointer to a function to handle elements of that type or > NULL if the type is not of interest. > > If the sublist is of interest, each element is passed to the handler > function in turn. There are a few checkpatch.pl warnings that need to be addressed, including the missing SPDX license. Mimi > > Signed-off-by: David Howells <dhowells@redhat.com> > Signed-off-by: Nayna Jain <nayna@linux.ibm.com> > --- > Changelog: > > v0: > - removed the CONFIG EFI_SIGNATURE_LIST_PARSER > - moved efi_parser.c from certs to security/integrity/platform_certs > directory > > include/linux/efi.h | 9 ++ > security/integrity/Makefile | 3 +- > security/integrity/platform_certs/efi_parser.c | 112 +++++++++++++++++++++++++ > 3 files changed, 123 insertions(+), 1 deletion(-) > create mode 100644 security/integrity/platform_certs/efi_parser.c > > diff --git a/include/linux/efi.h b/include/linux/efi.h > index 99cba6fe1234..2016145e2d6d 100644 > --- a/include/linux/efi.h > +++ b/include/linux/efi.h > @@ -1138,6 +1138,15 @@ extern int efi_memattr_apply_permissions(struct mm_struct *mm, > char * __init efi_md_typeattr_format(char *buf, size_t size, > const efi_memory_desc_t *md); > > + > +typedef void (*efi_element_handler_t)(const char *source, > + const void *element_data, > + size_t element_size); > +extern int __init parse_efi_signature_list( > + const char *source, > + const void *data, size_t size, > + efi_element_handler_t (*get_handler_for_guid)(const efi_guid_t *)); > + > /** > * efi_range_is_wc - check the WC bit on an address range > * @start: starting kvirt address > diff --git a/security/integrity/Makefile b/security/integrity/Makefile > index 046ffc1bb42d..6ee9058866cd 100644 > --- a/security/integrity/Makefile > +++ b/security/integrity/Makefile > @@ -9,7 +9,8 @@ integrity-y := iint.o > integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o > integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o > integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o > -integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o > +integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o \ > + platform_certs/efi_parser.o > > subdir-$(CONFIG_IMA) += ima > obj-$(CONFIG_IMA) += ima/ > diff --git a/security/integrity/platform_certs/efi_parser.c b/security/integrity/platform_certs/efi_parser.c > new file mode 100644 > index 000000000000..4e396f98f5c7 > --- /dev/null > +++ b/security/integrity/platform_certs/efi_parser.c > @@ -0,0 +1,112 @@ > +/* EFI signature/key/certificate list parser > + * > + * Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved. > + * Written by David Howells (dhowells@redhat.com) > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public Licence > + * as published by the Free Software Foundation; either version > + * 2 of the Licence, or (at your option) any later version. > + */ > + > +#define pr_fmt(fmt) "EFI: "fmt > +#include <linux/module.h> > +#include <linux/printk.h> > +#include <linux/err.h> > +#include <linux/efi.h> > + > +/** > + * parse_efi_signature_list - Parse an EFI signature list for certificates > + * @source: The source of the key > + * @data: The data blob to parse > + * @size: The size of the data blob > + * @get_handler_for_guid: Get the handler func for the sig type (or NULL) > + * > + * Parse an EFI signature list looking for elements of interest. A list is > + * made up of a series of sublists, where all the elements in a sublist are of > + * the same type, but sublists can be of different types. > + * > + * For each sublist encountered, the @get_handler_for_guid function is called > + * with the type specifier GUID and returns either a pointer to a function to > + * handle elements of that type or NULL if the type is not of interest. > + * > + * If the sublist is of interest, each element is passed to the handler > + * function in turn. > + * > + * Error EBADMSG is returned if the list doesn't parse correctly and 0 is > + * returned if the list was parsed correctly. No error can be returned from > + * the @get_handler_for_guid function or the element handler function it > + * returns. > + */ > +int __init parse_efi_signature_list( > + const char *source, > + const void *data, size_t size, > + efi_element_handler_t (*get_handler_for_guid)(const efi_guid_t *)) > +{ > + efi_element_handler_t handler; > + unsigned offs = 0; > + > + pr_devel("-->%s(,%zu)\n", __func__, size); > + > + while (size > 0) { > + const efi_signature_data_t *elem; > + efi_signature_list_t list; > + size_t lsize, esize, hsize, elsize; > + > + if (size < sizeof(list)) > + return -EBADMSG; > + > + memcpy(&list, data, sizeof(list)); > + pr_devel("LIST[%04x] guid=%pUl ls=%x hs=%x ss=%x\n", > + offs, > + list.signature_type.b, list.signature_list_size, > + list.signature_header_size, list.signature_size); > + > + lsize = list.signature_list_size; > + hsize = list.signature_header_size; > + esize = list.signature_size; > + elsize = lsize - sizeof(list) - hsize; > + > + if (lsize > size) { > + pr_devel("<--%s() = -EBADMSG [overrun @%x]\n", > + __func__, offs); > + return -EBADMSG; > + } > + > + if (lsize < sizeof(list) || > + lsize - sizeof(list) < hsize || > + esize < sizeof(*elem) || > + elsize < esize || > + elsize % esize != 0) { > + pr_devel("- bad size combo @%x\n", offs); > + return -EBADMSG; > + } > + > + handler = get_handler_for_guid(&list.signature_type); > + if (!handler) { > + data += lsize; > + size -= lsize; > + offs += lsize; > + continue; > + } > + > + data += sizeof(list) + hsize; > + size -= sizeof(list) + hsize; > + offs += sizeof(list) + hsize; > + > + for (; elsize > 0; elsize -= esize) { > + elem = data; > + > + pr_devel("ELEM[%04x]\n", offs); > + handler(source, > + &elem->signature_data, > + esize - sizeof(*elem)); > + > + data += esize; > + size -= esize; > + offs += esize; > + } > + } > + > + return 0; > +}
diff --git a/include/linux/efi.h b/include/linux/efi.h index 99cba6fe1234..2016145e2d6d 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1138,6 +1138,15 @@ extern int efi_memattr_apply_permissions(struct mm_struct *mm, char * __init efi_md_typeattr_format(char *buf, size_t size, const efi_memory_desc_t *md); + +typedef void (*efi_element_handler_t)(const char *source, + const void *element_data, + size_t element_size); +extern int __init parse_efi_signature_list( + const char *source, + const void *data, size_t size, + efi_element_handler_t (*get_handler_for_guid)(const efi_guid_t *)); + /** * efi_range_is_wc - check the WC bit on an address range * @start: starting kvirt address diff --git a/security/integrity/Makefile b/security/integrity/Makefile index 046ffc1bb42d..6ee9058866cd 100644 --- a/security/integrity/Makefile +++ b/security/integrity/Makefile @@ -9,7 +9,8 @@ integrity-y := iint.o integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o -integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o +integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o \ + platform_certs/efi_parser.o subdir-$(CONFIG_IMA) += ima obj-$(CONFIG_IMA) += ima/ diff --git a/security/integrity/platform_certs/efi_parser.c b/security/integrity/platform_certs/efi_parser.c new file mode 100644 index 000000000000..4e396f98f5c7 --- /dev/null +++ b/security/integrity/platform_certs/efi_parser.c @@ -0,0 +1,112 @@ +/* EFI signature/key/certificate list parser + * + * Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#define pr_fmt(fmt) "EFI: "fmt +#include <linux/module.h> +#include <linux/printk.h> +#include <linux/err.h> +#include <linux/efi.h> + +/** + * parse_efi_signature_list - Parse an EFI signature list for certificates + * @source: The source of the key + * @data: The data blob to parse + * @size: The size of the data blob + * @get_handler_for_guid: Get the handler func for the sig type (or NULL) + * + * Parse an EFI signature list looking for elements of interest. A list is + * made up of a series of sublists, where all the elements in a sublist are of + * the same type, but sublists can be of different types. + * + * For each sublist encountered, the @get_handler_for_guid function is called + * with the type specifier GUID and returns either a pointer to a function to + * handle elements of that type or NULL if the type is not of interest. + * + * If the sublist is of interest, each element is passed to the handler + * function in turn. + * + * Error EBADMSG is returned if the list doesn't parse correctly and 0 is + * returned if the list was parsed correctly. No error can be returned from + * the @get_handler_for_guid function or the element handler function it + * returns. + */ +int __init parse_efi_signature_list( + const char *source, + const void *data, size_t size, + efi_element_handler_t (*get_handler_for_guid)(const efi_guid_t *)) +{ + efi_element_handler_t handler; + unsigned offs = 0; + + pr_devel("-->%s(,%zu)\n", __func__, size); + + while (size > 0) { + const efi_signature_data_t *elem; + efi_signature_list_t list; + size_t lsize, esize, hsize, elsize; + + if (size < sizeof(list)) + return -EBADMSG; + + memcpy(&list, data, sizeof(list)); + pr_devel("LIST[%04x] guid=%pUl ls=%x hs=%x ss=%x\n", + offs, + list.signature_type.b, list.signature_list_size, + list.signature_header_size, list.signature_size); + + lsize = list.signature_list_size; + hsize = list.signature_header_size; + esize = list.signature_size; + elsize = lsize - sizeof(list) - hsize; + + if (lsize > size) { + pr_devel("<--%s() = -EBADMSG [overrun @%x]\n", + __func__, offs); + return -EBADMSG; + } + + if (lsize < sizeof(list) || + lsize - sizeof(list) < hsize || + esize < sizeof(*elem) || + elsize < esize || + elsize % esize != 0) { + pr_devel("- bad size combo @%x\n", offs); + return -EBADMSG; + } + + handler = get_handler_for_guid(&list.signature_type); + if (!handler) { + data += lsize; + size -= lsize; + offs += lsize; + continue; + } + + data += sizeof(list) + hsize; + size -= sizeof(list) + hsize; + offs += sizeof(list) + hsize; + + for (; elsize > 0; elsize -= esize) { + elem = data; + + pr_devel("ELEM[%04x]\n", offs); + handler(source, + &elem->signature_data, + esize - sizeof(*elem)); + + data += esize; + size -= esize; + offs += esize; + } + } + + return 0; +}