On Fri, 3 May 2019 at 09:18, joeyli <jlee@xxxxxxxx> wrote: > > Hi Ard, > > On Thu, May 02, 2019 at 11:04:34AM +0200, Ard Biesheuvel wrote: > > On Thu, 2 May 2019 at 06:04, Lee, Chun-Yi <joeyli.kernel@xxxxxxxxx> wrote: > > > > > > When loading certificates list from UEFI variable, the original error > > > message direct shows the efi status code from UEFI firmware. It looks > > > ugly: > > > > > > [ 2.335031] Couldn't get size: 0x800000000000000e > > > [ 2.335032] Couldn't get UEFI MokListRT > > > [ 2.339985] Couldn't get size: 0x800000000000000e > > > [ 2.339987] Couldn't get UEFI dbx list > > > > > > So, this patch shows the status string instead of status code. > > > > > > On the other hand, the "Couldn't get UEFI" message doesn't need > > > to be exposed when db/dbx/mok variable do not exist. So, this > > > patch set the message level to debug. > > > > > > v3. > > > - Print messages similar to db/mok when loading dbx hash to blacklist: > > > [ 1.500952] EFI: Blacklisting hash of an executable: UEFI:dbx > > > [ 1.501773] blacklist: Loaded blacklisting hash > > > 'bin:80b4d96931bf0d02fd91a61e19d14f1da452e66db2408ca8604d411f92659f0a' > > > > > > - Setting messages for the existence of db/mok/dbx lists to debug level. > > > > > > v2. > > > Setting the MODSIGN messages level to debug. > > > > > > Link: > > > https://forums.opensuse.org/showthread.php/535324-MODSIGN-Couldn-t-get-UEFI-db-list?p=2897516#post2897516 > > > Cc: James Morris <jmorris@xxxxxxxxx> > > > Cc: Serge E. Hallyn" <serge@xxxxxxxxxx> > > > Cc: David Howells <dhowells@xxxxxxxxxx> > > > Cc: Nayna Jain <nayna@xxxxxxxxxxxxx> > > > Cc: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx> > > > Cc: Mimi Zohar <zohar@xxxxxxxxxxxxx> > > > Signed-off-by: "Lee, Chun-Yi" <jlee@xxxxxxxx> > > > --- > > > certs/blacklist.c | 3 +- > > > security/integrity/platform_certs/load_uefi.c | 40 +++++++++++++++++++-------- > > > 2 files changed, 31 insertions(+), 12 deletions(-) > > > > > > diff --git a/certs/blacklist.c b/certs/blacklist.c > > > index 3a507b9e2568..f91437e39e44 100644 > > > --- a/certs/blacklist.c > > > +++ b/certs/blacklist.c > > > @@ -100,7 +100,8 @@ int mark_hash_blacklisted(const char *hash) > > > if (IS_ERR(key)) { > > > pr_err("Problem blacklisting hash (%ld)\n", PTR_ERR(key)); > > > return PTR_ERR(key); > > > - } > > > + } else > > > + pr_notice("Loaded blacklisting hash '%s'\n", hash); > > > return 0; > > > } > > > > > > diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c > > > index 81b19c52832b..6b6996e5bc27 100644 > > > --- a/security/integrity/platform_certs/load_uefi.c > > > +++ b/security/integrity/platform_certs/load_uefi.c > > > @@ -1,5 +1,7 @@ > > > // SPDX-License-Identifier: GPL-2.0 > > > > > > +#define pr_fmt(fmt) "EFI: "fmt > > > + > > > #include <linux/kernel.h> > > > #include <linux/sched.h> > > > #include <linux/cred.h> > > > @@ -35,6 +37,18 @@ static __init bool uefi_check_ignore_db(void) > > > return status == EFI_SUCCESS; > > > } > > > > > > +static void str16_to_str(efi_char16_t *str16, char *str, int str_size) > > > +{ > > > + int i = 0; > > > + > > > + while (str16[i] != '\0' && i < (str_size - 1)) { > > > + str[i] = str16[i]; > > > + i++; > > > + } > > > + > > > + str[i] = '\0'; > > > +} > > > + > > > /* > > > * Get a certificate list blob from the named EFI variable. > > > */ > > > @@ -44,13 +58,20 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, > > > efi_status_t status; > > > unsigned long lsize = 4; > > > unsigned long tmpdb[4]; > > > + char namestr[16]; > > > void *db; > > > > > > + str16_to_str(name, namestr, ARRAY_SIZE(namestr)); > > > > Please drop this (and the function above) - instead, just return NULL > > if the variable is not found (without reporting an error). > > > > This name string is for printing debug level message, not error message. > This function already returns NULL when EFI_NOT_FOUND be returned by > firmware. > > > > status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb); > > > if (status != EFI_BUFFER_TOO_SMALL) { > > > - pr_err("Couldn't get size: 0x%lx\n", status); > > > + if (status == EFI_NOT_FOUND) > > > + pr_debug("UEFI %s list doesn't exist\n", namestr); > > > + else > > > + pr_err("Couldn't get size for UEFI %s list: %s\n", > > > + namestr, efi_status_to_str(status)); > > > return NULL; > > here returns NULL when EFI_NOT_FOUND. The message of existence is for > debugging. > I understand that. But I don't think we need it. > > > } > > > + pr_debug("UEFI %s list exists\n", namestr); > > > > > > db = kmalloc(lsize, GFP_KERNEL); > > > if (!db) > > > @@ -59,7 +80,8 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, > > > status = efi.get_variable(name, guid, NULL, &lsize, db); > > > if (status != EFI_SUCCESS) { > > > kfree(db); > > > - pr_err("Error reading db var: 0x%lx\n", status); > > > + pr_err("Error reading UEFI %s list: %s\n", > > > + namestr, efi_status_to_str(status)); > > > return NULL; > > > } > > > > > > @@ -95,6 +117,7 @@ static __init void uefi_blacklist_hash(const char *source, const void *data, > > > static __init void uefi_blacklist_x509_tbs(const char *source, > > > const void *data, size_t len) > > > { > > > + pr_info("Blacklisting X.509 TBS hash: %s\n", source); > > > uefi_blacklist_hash(source, data, len, "tbs:", 4); > > > } > > > > > > @@ -104,6 +127,7 @@ static __init void uefi_blacklist_x509_tbs(const char *source, > > > static __init void uefi_blacklist_binary(const char *source, > > > const void *data, size_t len) > > > { > > > + pr_info("Blacklisting hash of an executable: %s\n", source); > > > uefi_blacklist_hash(source, data, len, "bin:", 4); > > > } > > > > > > > These are separate changes - I don't have an opinion whether they are > > appropriate or not, but they should be in a separate patch. > > > > I will move the message of blacklising hash to other patch. Thanks! > > > > @@ -154,9 +178,7 @@ static int __init load_uefi_certs(void) > > > */ > > > if (!uefi_check_ignore_db()) { > > > db = get_cert_list(L"db", &secure_var, &dbsize); > > > - if (!db) { > > > - pr_err("MODSIGN: Couldn't get UEFI db list\n"); > > > - } else { > > > + if (db) { > > > rc = parse_efi_signature_list("UEFI:db", > > > db, dbsize, get_handler_for_db); > > > if (rc) > > > @@ -167,9 +189,7 @@ static int __init load_uefi_certs(void) > > > } > > > > > > mok = get_cert_list(L"MokListRT", &mok_var, &moksize); > > > - if (!mok) { > > > - pr_info("Couldn't get UEFI MokListRT\n"); > > > - } else { > > > + if (mok) { > > > rc = parse_efi_signature_list("UEFI:MokListRT", > > > mok, moksize, get_handler_for_db); > > > if (rc) > > > @@ -178,9 +198,7 @@ static int __init load_uefi_certs(void) > > > } > > > > > > dbx = get_cert_list(L"dbx", &secure_var, &dbxsize); > > > - if (!dbx) { > > > - pr_info("Couldn't get UEFI dbx list\n"); > > > - } else { > > > + if (dbx) { > > > rc = parse_efi_signature_list("UEFI:dbx", > > > dbx, dbxsize, > > > get_handler_for_dbx); > > > -- > > > 2.16.4 > > > > > > > I think we should consider carefully what it means if some of these > > variables don't exist: > > - if secure boot is enabled, db and dbx must exist, so if they don't, > > something is wrong > > The existence of db/dbx is not related to secure boot. If manufacturer/user > enrolled certificate/hash to db or dbx, then the variable will be created. > If user didn't enroll anything to db/dbx, then variables will not show up. > Yes, but if secure boot is enabled and db is empty, how could you have booted in the first place? And what about the converse case: if secure boot is not enabled, why should we trust the contents of db? > > - secure boot might be enabled but we may be booting without shim. > > Shim always creates MokListRT no matter secure boot enabled or disabled. > That is not my point. What happens if you booted with secure boot enabled but without the help of shim? > > - secure boot might be disabled. > > > > It's not about secure boot, db/dbx/MokListRT are always available at > runtime if user was enrolled something to those list. > Yes, but again, depending on whether shim was involved, and/or whether secure boot was enabled or not, the way we interpret these things may be very different. I want the reasoning to be sound before merging any patches that deal with these variables.
