ima: define new template ima-ng and template fields d-ng and n-ng

This patch adds support for the new template 'ima-ng', whose format
is defined as 'd-ng|n-ng'.  These new field definitions remove the
size limitations of the original 'ima' template.  Further, the 'd-ng'
field prefixes the inode digest with the hash algorithim, when
displaying the new larger digest sizes.

Change log:
- scripts/Lindent fixes  - Mimi
- "always true comparison" - reported by Fengguang Wu, resolved Dmitry
- initialize hash_algo variable to HASH_ALGO__LAST
- always prefix digest with hash algorithm - Mimi

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

3 files changed, 150 insertions, 17 deletions

diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index 810042264396..bf38d1af3cfd 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -16,7 +16,8 @@
 #include "ima_template_lib.h"
 
 static struct ima_template_desc defined_templates[] = {
-        {.name = IMA_TEMPLATE_IMA_NAME,.fmt = IMA_TEMPLATE_IMA_FMT},
+        {.name = IMA_TEMPLATE_IMA_NAME, .fmt = IMA_TEMPLATE_IMA_FMT},
+        {.name = "ima-ng",.fmt = "d-ng|n-ng"},
 };
 
 static struct ima_template_field supported_fields[] = {
@@ -24,6 +25,10 @@ static struct ima_template_field supported_fields[] = {
          .field_show = ima_show_template_digest},
         {.field_id = "n",.field_init = ima_eventname_init,
          .field_show = ima_show_template_string},
+        {.field_id = "d-ng",.field_init = ima_eventdigest_ng_init,
+         .field_show = ima_show_template_digest_ng},
+        {.field_id = "n-ng",.field_init = ima_eventname_ng_init,
+         .field_show = ima_show_template_string},
 };
 
 static struct ima_template_field *lookup_template_field(const char *field_id)
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index e13fc7c04ebc..7d841448f246 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -12,9 +12,25 @@
  * File: ima_template_lib.c
  *      Library of supported template fields.
  */
+#include <crypto/hash_info.h>
+
 #include "ima_template_lib.h"
 
-enum data_formats { DATA_FMT_DIGEST = 0, DATA_FMT_EVENT_NAME, DATA_FMT_STRING };
+static bool ima_template_hash_algo_allowed(u8 algo)
+{
+        if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
+                return true;
+
+        return false;
+}
+
+enum data_formats {
+        DATA_FMT_DIGEST = 0,
+        DATA_FMT_DIGEST_WITH_ALGO,
+        DATA_FMT_EVENT_NAME,
+        DATA_FMT_STRING
+};
+
 static int ima_write_template_field_data(const void *data, const u32 datalen,
                                          enum data_formats datafmt,
                                          struct ima_field_data *field_data)
@@ -62,12 +78,22 @@ static void ima_show_template_data_ascii(struct seq_file *m,
                                          enum data_formats datafmt,
                                          struct ima_field_data *field_data)
 {
+        u8 *buf_ptr = field_data->data, buflen = field_data->len;
+
         switch (datafmt) {
+        case DATA_FMT_DIGEST_WITH_ALGO:
+                buf_ptr = strnchr(field_data->data, buflen, ':');
+                if (buf_ptr != field_data->data)
+                        seq_printf(m, "%s", field_data->data);
+
+                /* skip ':' and '\0' */
+                buf_ptr += 2;
+                buflen -= buf_ptr - field_data->data;
         case DATA_FMT_DIGEST:
-                ima_print_digest(m, field_data->data, field_data->len);
+                ima_print_digest(m, buf_ptr, buflen);
                 break;
         case DATA_FMT_STRING:
-                seq_printf(m, "%s", field_data->data);
+                seq_printf(m, "%s", buf_ptr);
                 break;
         default:
                 break;
@@ -108,14 +134,59 @@ void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
         ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
 }
 
+void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
+                                 struct ima_field_data *field_data)
+{
+        ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
+                                     field_data);
+}
+
 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
                               struct ima_field_data *field_data)
 {
         ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
 }
 
+static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
+                                       struct ima_field_data *field_data,
+                                       bool size_limit)
+{
+        /*
+         * digest formats:
+         *  - DATA_FMT_DIGEST: digest
+         *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
+         *    where <hash algo> is provided if the hash algoritm is not
+         *    SHA1 or MD5
+         */
+        u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
+        enum data_formats fmt = DATA_FMT_DIGEST;
+        u32 offset = 0;
+
+        if (!size_limit) {
+                fmt = DATA_FMT_DIGEST_WITH_ALGO;
+                if (hash_algo < HASH_ALGO__LAST)
+                        offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1,
+                                           "%s", hash_algo_name[hash_algo]);
+                buffer[offset] = ':';
+                offset += 2;
+        }
+
+        if (digest)
+                memcpy(buffer + offset, digest, digestsize);
+        else
+                /*
+                 * If digest is NULL, the event being recorded is a violation.
+                 * Make room for the digest by increasing the offset of
+                 * IMA_DIGEST_SIZE.
+                 */
+                offset += IMA_DIGEST_SIZE;
+
+        return ima_write_template_field_data(buffer, offset + digestsize,
+                                             fmt, field_data);
+}
+
 /*
- * This function writes the digest of an event.
+ * This function writes the digest of an event (with size limit).
  */
 int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
                          const unsigned char *filename,
@@ -125,8 +196,8 @@ int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
                 struct ima_digest_data hdr;
                 char digest[IMA_MAX_DIGEST_SIZE];
         } hash;
-        u8 *cur_digest = hash.hdr.digest;
-        u32 cur_digestsize = IMA_DIGEST_SIZE;
+        u8 *cur_digest = NULL;
+        u32 cur_digestsize = 0;
         struct inode *inode;
         int result;
 
@@ -135,7 +206,7 @@ int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
         if (!iint)              /* recording a violation. */
                 goto out;
 
-        if (iint->ima_hash->algo == ima_hash_algo) {
+        if (ima_template_hash_algo_allowed(iint->ima_hash->algo)) {
                 cur_digest = iint->ima_hash->digest;
                 cur_digestsize = iint->ima_hash->length;
                 goto out;
@@ -145,7 +216,8 @@ int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
                 return -EINVAL;
 
         inode = file_inode(file);
-        hash.hdr.algo = ima_hash_algo;
+        hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
+            ima_hash_algo : HASH_ALGO_SHA1;
         result = ima_calc_file_hash(file, &hash.hdr);
         if (result) {
                 integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
@@ -153,20 +225,46 @@ int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
                                     "failed", result, 0);
                 return result;
         }
+        cur_digest = hash.hdr.digest;
+        cur_digestsize = hash.hdr.length;
 out:
-        return ima_write_template_field_data(cur_digest, cur_digestsize,
-                                             DATA_FMT_DIGEST, field_data);
+        return ima_eventdigest_init_common(cur_digest, cur_digestsize, -1,
+                                           field_data, true);
 }
 
 /*
- * This function writes the name of an event.
+ * This function writes the digest of an event (without size limit).
  */
-int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
-                       const unsigned char *filename,
-                       struct ima_field_data *field_data)
+int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
+                            struct file *file, const unsigned char *filename,
+                            struct ima_field_data *field_data)
+{
+        u8 *cur_digest = NULL, hash_algo = HASH_ALGO__LAST;
+        u32 cur_digestsize = 0;
+
+        /* If iint is NULL, we are recording a violation. */
+        if (!iint)
+                goto out;
+
+        cur_digest = iint->ima_hash->digest;
+        cur_digestsize = iint->ima_hash->length;
+
+        hash_algo = iint->ima_hash->algo;
+out:
+        return ima_eventdigest_init_common(cur_digest, cur_digestsize,
+                                           hash_algo, field_data, false);
+}
+
+static int ima_eventname_init_common(struct integrity_iint_cache *iint,
+                                     struct file *file,
+                                     const unsigned char *filename,
+                                     struct ima_field_data *field_data,
+                                     bool size_limit)
 {
         const char *cur_filename = NULL;
         u32 cur_filename_len = 0;
+        enum data_formats fmt = size_limit ?
+            DATA_FMT_EVENT_NAME : DATA_FMT_STRING;
 
         BUG_ON(filename == NULL && file == NULL);
 
@@ -174,7 +272,7 @@ int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
                 cur_filename = filename;
                 cur_filename_len = strlen(filename);
 
-                if (cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
+                if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
                         goto out;
         }
 
@@ -189,5 +287,27 @@ int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
                 cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
 out:
         return ima_write_template_field_data(cur_filename, cur_filename_len,
-                                             DATA_FMT_EVENT_NAME, field_data);
+                                             fmt, field_data);
+}
+
+/*
+ * This function writes the name of an event (with size limit).
+ */
+int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
+                       const unsigned char *filename,
+                       struct ima_field_data *field_data)
+{
+        return ima_eventname_init_common(iint, file, filename,
+                                         field_data, true);
+}
+
+/*
+ * This function writes the name of an event (without size limit).
+ */
+int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file,
+                          const unsigned char *filename,
+                          struct ima_field_data *field_data)
+{
+        return ima_eventname_init_common(iint, file, filename,
+                                         field_data, false);
 }
diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h
index 2cecc83a928d..16c5e7810234 100644
--- a/security/integrity/ima/ima_template_lib.h
+++ b/security/integrity/ima/ima_template_lib.h
@@ -20,6 +20,8 @@
 
 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
                               struct ima_field_data *field_data);
+void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
+                                 struct ima_field_data *field_data);
 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
                               struct ima_field_data *field_data);
 int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
@@ -28,4 +30,10 @@ int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
 int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
                        const unsigned char *filename,
                        struct ima_field_data *field_data);
+int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
+                            struct file *file, const unsigned char *filename,
+                            struct ima_field_data *field_data);
+int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file,
+                          const unsigned char *filename,
+                          struct ima_field_data *field_data);
 #endif /* __LINUX_IMA_TEMPLATE_LIB_H */