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Rename "--validate" to "--ignore-violations"

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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@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Mimi Zohar
2020-07-29 16:44:09 -04:00
parent 5b58f47570
commit 62534f2127
2 changed files with 9 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
README
View File

@@ -31,7 +31,7 @@ COMMANDS
ima_sign [--sigfile] [--key key] [--pass password] file ima_sign [--sigfile] [--key key] [--pass password] file
ima_verify file ima_verify file
ima_hash 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 ima_fix [-t fdsxm] path
sign_hash [--key key] [--pass password] sign_hash [--key key] [--pass password]
hmac [--imahash | --imasig ] file hmac [--imahash | --imasig ] file
@@ -60,7 +60,7 @@ OPTIONS
--m64 force EVM hmac/signature for 64 bit target system --m64 force EVM hmac/signature for 64 bit target system
--engine e preload OpenSSL engine e (such as: gost) --engine e preload OpenSSL engine e (such as: gost)
--pcrs file containing TPM pcrs, one per hash-algorithm/bank --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 --verify-sig verify the file signature based on the file hash, both
stored in the template data. stored in the template data.
-v increase verbosity level -v increase verbosity level

13
src/evmctl.c
View File

@@ -1392,7 +1392,7 @@ struct template_entry {
static uint8_t zero[MAX_DIGEST_SIZE]; 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) 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. * size.
*/ */
if (memcmp(entry->header.digest, zero, SHA_DIGEST_LENGTH) == 0) { 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(bank[i].digest, 0x00, bank[i].digest_size);
memset(padded_bank[i].digest, 0x00, padded_bank[i].digest_size); memset(padded_bank[i].digest, 0x00, padded_bank[i].digest_size);
} else { } else {
@@ -2467,6 +2467,7 @@ static void usage(void)
" --caps use custom Capabilities for EVM(unspecified: from FS, empty: do not use)\n" " --caps use custom Capabilities for EVM(unspecified: from FS, empty: do not use)\n"
" --verify-sig verify measurement list signatures\n" " --verify-sig verify measurement list signatures\n"
" --engine e preload OpenSSL engine e (such as: gost)\n" " --engine e preload OpenSSL engine e (such as: gost)\n"
" --ignore-violations ignore ToMToU measurement violations"
" -v increase verbosity level\n" " -v increase verbosity level\n"
" -h, --help display this help and exit\n" " -h, --help display this help and exit\n"
"\n"); "\n");
@@ -2483,7 +2484,7 @@ struct command cmds[] = {
{"ima_verify", cmd_verify_ima, 0, "file", "Verify IMA signature (for debugging).\n"}, {"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_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_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_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_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"}, {"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}, {"verify-sig", 0, 0, 138},
{"engine", 1, 0, 139}, {"engine", 1, 0, 139},
{"xattr-user", 0, 0, 140}, {"xattr-user", 0, 0, 140},
{"validate", 0, 0, 141}, {"ignore-violations", 0, 0, 141},
{"pcrs", 1, 0, 142}, {"pcrs", 1, 0, 142},
{} {}
@@ -2702,8 +2703,8 @@ int main(int argc, char *argv[])
xattr_ima = "user.ima"; xattr_ima = "user.ima";
xattr_evm = "user.evm"; xattr_evm = "user.evm";
break; break;
case 141: /* --validate */ case 141: /* --ignore-violations */
validate = 1; ignore_violations = 1;
break; break;
case 142: case 142:
if (npcrfile >= MAX_PCRFILE) { if (npcrfile >= MAX_PCRFILE) {