hulk inclusion category: feature feature: digest-lists
---------------------------
IMA-Measure creates a new measurement entry every time a file is measured, unless the same entry is already in the measurement list.
This patch introduces a new type of measurement list, recognizable by the PCR number specified with the new ima_digest_list_pcr= kernel option. This type of measurement list includes measurements of digest lists and files not found in those lists.
The benefit of this patch is the availability of a predictable PCR that can be used to seal data or TPM keys to the OS software. Unlike standard measurements, digest list measurements only indicate that files with a digest in those lists could have been accessed, but not if and when. With standard measurements, however, the chosen PCR is unlikely predictable.
Both standard and digest list measurements can be generated at the same time by adding '+' as a prefix to the value of ima_digest_list_pcr= (example: with ima_digest_list_pcr=+11, IMA generates standard measurements with PCR 10 and digest list measurements with PCR 11).
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- .../admin-guide/kernel-parameters.txt | 9 ++++ security/integrity/ima/ima.h | 9 ++-- security/integrity/ima/ima_api.c | 43 ++++++++++++++++--- security/integrity/ima/ima_digest_list.c | 25 +++++++++++ security/integrity/ima/ima_init.c | 2 +- security/integrity/ima/ima_main.c | 16 ++++++- security/integrity/ima/ima_policy.c | 3 +- security/integrity/integrity.h | 1 + 8 files changed, 95 insertions(+), 13 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 7b4487f08ea1..d6423042d787 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1565,6 +1565,15 @@ Use the canonical format for the binary runtime measurements, instead of host native format.
+ ima_digest_list_pcr= + [IMA] + Specify which PCR is extended when file digests are + not found in the loaded digest lists. If '+' is not + specified, no measurement entry is created if the + digest is found. Otherwise, IMA creates also entries + with PCR 10, according to the existing behavior. + Format: { [+]<unsigned int> } + ima_hash= [IMA] Format: { md5 | sha1 | rmd160 | sha256 | sha384 | sha512 | ... } diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index c8cd23bb8b8c..dbdbd9c84262 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -56,6 +56,8 @@ extern int ima_policy_flag; extern int ima_hash_algo; extern int ima_appraise; extern struct tpm_chip *ima_tpm_chip; +extern int ima_digest_list_pcr; +extern bool ima_plus_standard_pcr; extern const char boot_aggregate_name[]; extern int ima_digest_list_actions;
@@ -204,14 +206,15 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len, int pcr); + int xattr_len, int pcr, + struct ima_digest *digest); void ima_audit_measurement(struct integrity_iint_cache *iint, const unsigned char *filename); int ima_alloc_init_template(struct ima_event_data *event_data, struct ima_template_entry **entry); int ima_store_template(struct ima_template_entry *entry, int violation, - struct inode *inode, - const unsigned char *filename, int pcr); + struct inode *inode, const unsigned char *filename, + int pcr, struct ima_digest *digest); void ima_free_template_entry(struct ima_template_entry *entry); const char *ima_d_path(const struct path *path, char **pathbuf, char *filename);
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index a02c5acfd403..3c0eb503e3ab 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -88,11 +88,13 @@ int ima_alloc_init_template(struct ima_event_data *event_data, */ int ima_store_template(struct ima_template_entry *entry, int violation, struct inode *inode, - const unsigned char *filename, int pcr) + const unsigned char *filename, int pcr, + struct ima_digest *digest) { static const char op[] = "add_template_measure"; static const char audit_cause[] = "hashing_error"; char *template_name = entry->template_desc->name; + struct ima_template_entry *duplicated_entry = NULL; int result; struct { struct ima_digest_data hdr; @@ -115,8 +117,27 @@ int ima_store_template(struct ima_template_entry *entry, } memcpy(entry->digest, hash.hdr.digest, hash.hdr.length); } + + if (ima_plus_standard_pcr && !digest) { + duplicated_entry = kmemdup(entry, + sizeof(*entry) + entry->template_desc->num_fields * + sizeof(struct ima_field_data), GFP_KERNEL); + if (duplicated_entry) + duplicated_entry->pcr = ima_digest_list_pcr; + } else if (!ima_plus_standard_pcr && ima_digest_list_pcr >= 0) { + pcr = ima_digest_list_pcr; + } + entry->pcr = pcr; + result = ima_add_template_entry(entry, violation, op, inode, filename); + if (!result && duplicated_entry) { + result = ima_add_template_entry(duplicated_entry, violation, op, + inode, filename); + if (result < 0) + kfree(duplicated_entry); + } + return result; }
@@ -146,8 +167,8 @@ void ima_add_violation(struct file *file, const unsigned char *filename, result = -ENOMEM; goto err_out; } - result = ima_store_template(entry, violation, inode, - filename, CONFIG_IMA_MEASURE_PCR_IDX); + result = ima_store_template(entry, violation, inode, filename, + CONFIG_IMA_MEASURE_PCR_IDX, NULL); if (result < 0) ima_free_template_entry(entry); err_out: @@ -277,13 +298,14 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len, int pcr) + int xattr_len, int pcr, + struct ima_digest *digest) { static const char op[] = "add_template_measure"; static const char audit_cause[] = "ENOMEM"; int result = -ENOMEM; struct inode *inode = file_inode(file); - struct ima_template_entry *entry; + struct ima_template_entry *entry = NULL; struct ima_event_data event_data = {iint, file, filename, xattr_value, xattr_len, NULL}; int violation = 0; @@ -291,6 +313,11 @@ void ima_store_measurement(struct integrity_iint_cache *iint, if (iint->measured_pcrs & (0x1 << pcr)) return;
+ if (digest && !ima_plus_standard_pcr && ima_digest_list_pcr >= 0) { + result = -EEXIST; + goto out; + } + result = ima_alloc_init_template(&event_data, &entry); if (result < 0) { integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, @@ -298,12 +325,14 @@ void ima_store_measurement(struct integrity_iint_cache *iint, return; }
- result = ima_store_template(entry, violation, inode, filename, pcr); + result = ima_store_template(entry, violation, inode, filename, pcr, + digest); +out: if ((!result || result == -EEXIST) && !(file->f_flags & O_DIRECT)) { iint->flags |= IMA_MEASURED; iint->measured_pcrs |= (0x1 << pcr); } - if (result < 0) + if (result < 0 && entry) ima_free_template_entry(entry); }
diff --git a/security/integrity/ima/ima_digest_list.c b/security/integrity/ima/ima_digest_list.c index 607a33ba52ee..7e901bdb4340 100644 --- a/security/integrity/ima/ima_digest_list.c +++ b/security/integrity/ima/ima_digest_list.c @@ -28,6 +28,31 @@ struct ima_h_table ima_digests_htable = { .queue[0 ... IMA_MEASURE_HTABLE_SIZE - 1] = HLIST_HEAD_INIT };
+static int __init digest_list_pcr_setup(char *str) +{ + int pcr, ret; + + ret = kstrtouint(str, 10, &pcr); + if (ret) { + pr_err("Invalid PCR number %s\n", str); + return 1; + } + + if (pcr == CONFIG_IMA_MEASURE_PCR_IDX) { + pr_err("Default PCR cannot be used for digest lists\n"); + return 1; + } + + ima_digest_list_pcr = pcr; + ima_digest_list_actions |= IMA_MEASURE; + + if (*str == '+') + ima_plus_standard_pcr = true; + + return 1; +} +__setup("ima_digest_list_pcr=", digest_list_pcr_setup); + /************************* * Get/add/del functions * *************************/ diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c index a2bc4cb4482a..af19454788cb 100644 --- a/security/integrity/ima/ima_init.c +++ b/security/integrity/ima/ima_init.c @@ -80,7 +80,7 @@ static int __init ima_add_boot_aggregate(void)
result = ima_store_template(entry, violation, NULL, boot_aggregate_name, - CONFIG_IMA_MEASURE_PCR_IDX); + CONFIG_IMA_MEASURE_PCR_IDX, NULL); if (result < 0) { ima_free_template_entry(entry); audit_cause = "store_entry"; diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 5e30bf38c7de..198b2b4c3654 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -31,6 +31,7 @@ #include <linux/fs.h>
#include "ima.h" +#include "ima_digest_list.h"
#ifdef CONFIG_IMA_APPRAISE int ima_appraise = IMA_APPRAISE_ENFORCE; @@ -42,6 +43,10 @@ int ima_hash_algo = HASH_ALGO_SHA256;
/* Actions (measure/appraisal) for which digest lists can be used */ int ima_digest_list_actions; +/* PCR used for digest list measurements */ +int ima_digest_list_pcr = -1; +/* Flag to include standard measurement if digest list PCR is specified */ +bool ima_plus_standard_pcr;
static int hash_setup_done;
@@ -141,6 +146,8 @@ static enum hash_algo ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, return ima_hash_algo; return sig->hash_algo; break; + case EVM_IMA_XATTR_DIGEST_LIST: + /* fall through */ case IMA_XATTR_DIGEST_NG: ret = xattr_value->digest[0]; if (ret < HASH_ALGO__LAST) @@ -233,6 +240,7 @@ static int process_measurement(struct file *file, const struct cred *cred, const char *pathname = NULL; int rc = 0, action, must_appraise = 0; int pcr = CONFIG_IMA_MEASURE_PCR_IDX; + struct ima_digest *found_digest; struct evm_ima_xattr_data *xattr_value = NULL; int xattr_len = 0; bool violation_check; @@ -346,9 +354,15 @@ static int process_measurement(struct file *file, const struct cred *cred, if (!pathname || strlen(pathname) > IMA_EVENT_NAME_LEN_MAX) pathname = file->f_path.dentry->d_name.name;
+ found_digest = ima_lookup_digest(iint->ima_hash->digest, hash_algo, + COMPACT_FILE); + if (action & IMA_MEASURE) ima_store_measurement(iint, file, pathname, - xattr_value, xattr_len, pcr); + xattr_value, xattr_len, pcr, + ima_digest_allow(found_digest, + IMA_MEASURE)); + if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) { inode_lock(inode); rc = ima_appraise_measurement(func, iint, file, pathname, diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index ac49f07e8997..8ffd5958ae3e 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -971,7 +971,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) ima_log_string(ab, "pcr", args[0].from);
result = kstrtoint(args[0].from, 10, &entry->pcr); - if (result || INVALID_PCR(entry->pcr)) + if (result || INVALID_PCR(entry->pcr) || + entry->pcr == ima_digest_list_pcr) result = -EINVAL; else entry->flags |= IMA_PCR; diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 73550ebe9372..02d40e5f401c 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -75,6 +75,7 @@ enum evm_ima_xattr_type { EVM_IMA_XATTR_DIGSIG, IMA_XATTR_DIGEST_NG, EVM_XATTR_PORTABLE_DIGSIG, + EVM_IMA_XATTR_DIGEST_LIST, IMA_XATTR_LAST };