IMA records file "Time of Measure, Time of Use (ToMToU)" and "open
writers" integrity violations by adding a record to the measurement
list containing one value (0x00's), but extending the TPM with a
different value (0xFF's).
To avoid known file integrity violations, the builtin "tcb" measurement
policy should be replaced with a custom policy as early as possible.
This patch renames the existing "--validate" option to
"--ignore-violations".
Suggested-by: Stephen Smalley <stephen.smalley.work@xxxxxxxxx>
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
---
README | 4 ++--
src/evmctl.c | 13 +++++++------
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/README b/README
index d8b8f404534b..b37325f31802 100644
--- a/README
+++ b/README
@@ -31,7 +31,7 @@ COMMANDS
ima_sign [--sigfile] [--key key] [--pass password] file
ima_verify file
ima_hash file
- ima_measurement [--validate] [--verify-sig [--key "key1, key2, ..."]] [--pcrs [hash-algorithm,]file [--pcrs hash-algorithm,file] ...] file
+ ima_measurement [--ignore-violations] [--verify-sig [--key "key1, key2, ..."]] [--pcrs [hash-algorithm,]file [--pcrs hash-algorithm,file] ...] file
ima_fix [-t fdsxm] path
sign_hash [--key key] [--pass password]
hmac [--imahash | --imasig ] file
@@ -60,7 +60,7 @@ OPTIONS
--m64 force EVM hmac/signature for 64 bit target system
--engine e preload OpenSSL engine e (such as: gost)
--pcrs file containing TPM pcrs, one per hash-algorithm/bank
- --validate ignore ToMToU measurement violations
+ --ignore-violations ignore ToMToU measurement violations
--verify-sig verify the file signature based on the file hash, both
stored in the template data.
-v increase verbosity level
diff --git a/src/evmctl.c b/src/evmctl.c
index b4d2333fb880..7ad11507487f 100644
--- a/src/evmctl.c
+++ b/src/evmctl.c
@@ -1392,7 +1392,7 @@ struct template_entry {
static uint8_t zero[MAX_DIGEST_SIZE];
-static int validate = 0;
+static int ignore_violations = 0;
static int ima_verify_template_hash(struct template_entry *entry)
{
@@ -1739,7 +1739,7 @@ static void extend_tpm_banks(struct template_entry *entry, int num_banks,
* size.
*/
if (memcmp(entry->header.digest, zero, SHA_DIGEST_LENGTH) == 0) {
- if (!validate) {
+ if (!ignore_violations) {
memset(bank[i].digest, 0x00, bank[i].digest_size);
memset(padded_bank[i].digest, 0x00, padded_bank[i].digest_size);
} else {
@@ -2467,6 +2467,7 @@ static void usage(void)
" --caps use custom Capabilities for EVM(unspecified: from FS, empty: do not use)\n"
" --verify-sig verify measurement list signatures\n"
" --engine e preload OpenSSL engine e (such as: gost)\n"
+ " --ignore-violations ignore ToMToU measurement violations"
" -v increase verbosity level\n"
" -h, --help display this help and exit\n"
"\n");
@@ -2483,7 +2484,7 @@ struct command cmds[] = {
{"ima_verify", cmd_verify_ima, 0, "file", "Verify IMA signature (for debugging).\n"},
{"ima_setxattr", cmd_setxattr_ima, 0, "[--sigfile file]", "Set IMA signature from sigfile\n"},
{"ima_hash", cmd_hash_ima, 0, "file", "Make file content hash.\n"},
- {"ima_measurement", cmd_ima_measurement, 0, "[--validate] [--verify-sig [--key key1, key2, ...]] [--pcrs [hash-algorithm,]file [--pcrs hash-algorithm,file] ...] file", "Verify measurement list (experimental).\n"},
+ {"ima_measurement", cmd_ima_measurement, 0, "[--ignore-violations] [--verify-sig [--key key1, key2, ...]] [--pcrs [hash-algorithm,]file [--pcrs hash-algorithm,file] ...] file", "Verify measurement list (experimental).\n"},
{"ima_boot_aggregate", cmd_ima_bootaggr, 0, "[file]", "Calculate per TPM bank boot_aggregate digests\n"},
{"ima_fix", cmd_ima_fix, 0, "[-t fdsxm] path", "Recursively fix IMA/EVM xattrs in fix mode.\n"},
{"ima_clear", cmd_ima_clear, 0, "[-t fdsxm] path", "Recursively remove IMA/EVM xattrs.\n"},
@@ -2522,7 +2523,7 @@ static struct option opts[] = {
{"verify-sig", 0, 0, 138},
{"engine", 1, 0, 139},
{"xattr-user", 0, 0, 140},
- {"validate", 0, 0, 141},
+ {"ignore-violations", 0, 0, 141},
{"pcrs", 1, 0, 142},
{}
@@ -2702,8 +2703,8 @@ int main(int argc, char *argv[])
xattr_ima = "user.ima";
xattr_evm = "user.evm";
break;
- case 141: /* --validate */
- validate = 1;
+ case 141: /* --ignore-violations */
+ ignore_violations = 1;
break;
case 142:
if (npcrfile >= MAX_PCRFILE) {
--
2.18.4
