ima: switch to new template management mechanism

This patch performs the switch to the new template mechanism by modifying
the functions ima_alloc_init_template(), ima_measurements_show() and
ima_ascii_measurements_show(). The old function ima_template_show() was
removed as it is no longer needed. Also, if the template descriptor used
to generate a measurement entry is not 'ima', the whole length of field
data stored for an entry is provided before the data itself through the
binary_runtime_measurement interface.

Changelog:
- unnecessary to use strncmp() (Mimi Zohar)
- create new variable 'field' in ima_alloc_init_template() (Roberto Sassu)
- use GFP_NOFS flag in ima_alloc_init_template() (Roberto Sassu)
- new variable 'num_fields' in ima_store_template() (Roberto Sassu,
  proposed by Mimi Zohar)
- rename ima_calc_buffer_hash/template_hash() to ima_calc_field_array_hash(),
  something more generic (Mimi, requested by Dmitry)
- sparse error fix - Fengguang Wu
- fix lindent warnings
- always include the field length in the template data length
- include the template field length variable size in the template data length
- include both the template field data and field length in the template digest
  calculation. Simplifies verifying the template digest. (Mimi)

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

5 files changed, 107 insertions, 97 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index e1f081d65dbf..72d013e190b1 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -72,17 +72,11 @@ struct ima_template_desc {
         struct ima_template_field **fields;
 };
 
-/* IMA inode template definition */
-struct ima_template_data {
-        u8 digest[IMA_DIGEST_SIZE];     /* sha1/md5 measurement hash */
-        char file_name[IMA_EVENT_NAME_LEN_MAX + 1];     /* name + \0 */
-};
-
 struct ima_template_entry {
         u8 digest[TPM_DIGEST_SIZE];     /* sha1 or md5 measurement hash */
-        const char *template_name;
-        int template_len;
-        struct ima_template_data template;
+        struct ima_template_desc *template_desc; /* template descriptor */
+        u32 template_data_len;
+        struct ima_field_data template_data[0]; /* template related data */
 };
 
 struct ima_queue_entry {
@@ -102,14 +96,16 @@ int ima_add_template_entry(struct ima_template_entry *entry, int violation,
                            const char *op, struct inode *inode,
                            const unsigned char *filename);
 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash);
-int ima_calc_buffer_hash(const void *data, int len,
-                         struct ima_digest_data *hash);
+int ima_calc_field_array_hash(struct ima_field_data *field_data, int num_fields,
+                              struct ima_digest_data *hash);
 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash);
 void ima_add_violation(struct file *file, const unsigned char *filename,
                        const char *op, const char *cause);
 int ima_init_crypto(void);
 void ima_putc(struct seq_file *m, void *data, int datalen);
 void ima_print_digest(struct seq_file *m, u8 *digest, int size);
+struct ima_template_desc *ima_template_desc_current(void);
+int ima_init_template(void);
 
 int ima_init_template(void);
 
@@ -146,7 +142,6 @@ int ima_alloc_init_template(struct integrity_iint_cache *iint,
                             struct ima_template_entry **entry);
 int ima_store_template(struct ima_template_entry *entry, int violation,
                        struct inode *inode, const unsigned char *filename);
-void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show);
 const char *ima_d_path(struct path *path, char **pathbuf);
 
 /* rbtree tree calls to lookup, insert, delete
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 29dd43de823a..baa348179527 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -21,8 +21,6 @@
 #include <crypto/hash_info.h>
 #include "ima.h"
 
-static const char *IMA_TEMPLATE_NAME = "ima";
-
 /*
  * ima_alloc_init_template - create and initialize a new template entry
  */
@@ -30,52 +28,32 @@ int ima_alloc_init_template(struct integrity_iint_cache *iint,
                             struct file *file, const unsigned char *filename,
                             struct ima_template_entry **entry)
 {
-        struct ima_template_entry *e;
-        int result = 0;
+        struct ima_template_desc *template_desc = ima_template_desc_current();
+        int i, result = 0;
 
-        e = kzalloc(sizeof(**entry), GFP_NOFS);
-        if (!e)
+        *entry = kzalloc(sizeof(**entry) + template_desc->num_fields *
+                         sizeof(struct ima_field_data), GFP_NOFS);
+        if (!*entry)
                 return -ENOMEM;
 
-        memset(&(e)->template, 0, sizeof(e->template));
-        if (!iint)              /* IMA measurement violation entry */
-                goto out;
-
-        if (iint->ima_hash->algo != ima_hash_algo) {
-                struct inode *inode;
-                struct {
-                        struct ima_digest_data hdr;
-                        char digest[IMA_MAX_DIGEST_SIZE];
-                } hash;
+        for (i = 0; i < template_desc->num_fields; i++) {
+                struct ima_template_field *field = template_desc->fields[i];
+                u32 len;
 
-                if (!file) {
-                        result = -EINVAL;
-                        goto out_free;
-                }
+                result = field->field_init(iint, file, filename,
+                                           &((*entry)->template_data[i]));
+                if (result != 0)
+                        goto out;
 
-                inode = file_inode(file);
-                hash.hdr.algo = ima_hash_algo;
-                hash.hdr.length = SHA1_DIGEST_SIZE;
-                result = ima_calc_file_hash(file, &hash.hdr);
-                if (result) {
-                        integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
-                                            filename, "collect_data",
-                                            "failed", result, 0);
-                        goto out_free;
-                } else
-                        memcpy(e->template.digest, hash.hdr.digest,
-                               hash.hdr.length);
-        } else
-                memcpy(e->template.digest, iint->ima_hash->digest,
-                       iint->ima_hash->length);
-out:
-        strcpy(e->template.file_name,
-               (strlen(filename) > IMA_EVENT_NAME_LEN_MAX && file != NULL) ?
-               file->f_dentry->d_name.name : filename);
-        *entry = e;
+                len = (*entry)->template_data[i].len;
+                (*entry)->template_data_len += sizeof(len);
+                (*entry)->template_data_len += len;
+        }
+        (*entry)->template_desc = template_desc;
         return 0;
-out_free:
-        kfree(e);
+out:
+        kfree(*entry);
+        *entry = NULL;
         return result;
 }
 
@@ -101,24 +79,23 @@ int ima_store_template(struct ima_template_entry *entry,
 {
         const char *op = "add_template_measure";
         const char *audit_cause = "hashing_error";
+        char *template_name = entry->template_desc->name;
         int result;
         struct {
                 struct ima_digest_data hdr;
                 char digest[TPM_DIGEST_SIZE];
         } hash;
 
-        memset(entry->digest, 0, sizeof(entry->digest));
-        entry->template_name = IMA_TEMPLATE_NAME;
-        entry->template_len = sizeof(entry->template);
-
         if (!violation) {
+                int num_fields = entry->template_desc->num_fields;
+
                 /* this function uses default algo */
                 hash.hdr.algo = HASH_ALGO_SHA1;
-                result = ima_calc_buffer_hash(&entry->template,
-                                              entry->template_len, &hash.hdr);
+                result = ima_calc_field_array_hash(&entry->template_data[0],
+                                                   num_fields, &hash.hdr);
                 if (result < 0) {
                         integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
-                                            entry->template_name, op,
+                                            template_name, op,
                                             audit_cause, result, 0);
                         return result;
                 }
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 22be23f13b3d..676e0292dfec 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -137,26 +137,46 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 }
 
 /*
- * Calculate the hash of a given buffer
+ * Calculate the hash of template data
  */
-static int ima_calc_buffer_hash_tfm(const void *buf, int len,
-                                    struct ima_digest_data *hash,
-                                    struct crypto_shash *tfm)
+static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
+                                         int num_fields,
+                                         struct ima_digest_data *hash,
+                                         struct crypto_shash *tfm)
 {
         struct {
                 struct shash_desc shash;
                 char ctx[crypto_shash_descsize(tfm)];
         } desc;
+        int rc, i;
 
         desc.shash.tfm = tfm;
         desc.shash.flags = 0;
 
         hash->length = crypto_shash_digestsize(tfm);
 
-        return crypto_shash_digest(&desc.shash, buf, len, hash->digest);
+        rc = crypto_shash_init(&desc.shash);
+        if (rc != 0)
+                return rc;
+
+        for (i = 0; i < num_fields; i++) {
+                rc = crypto_shash_update(&desc.shash,
+                                         (const u8 *) &field_data[i].len,
+                                         sizeof(field_data[i].len));
+                rc = crypto_shash_update(&desc.shash, field_data[i].data,
+                                         field_data[i].len);
+                if (rc)
+                        break;
+        }
+
+        if (!rc)
+                rc = crypto_shash_final(&desc.shash, hash->digest);
+
+        return rc;
 }
 
-int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash)
+int ima_calc_field_array_hash(struct ima_field_data *field_data, int num_fields,
+                              struct ima_digest_data *hash)
 {
         struct crypto_shash *tfm;
         int rc;
@@ -165,7 +185,7 @@ int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash)
         if (IS_ERR(tfm))
                 return PTR_ERR(tfm);
 
-        rc = ima_calc_buffer_hash_tfm(buf, len, hash, tfm);
+        rc = ima_calc_field_array_hash_tfm(field_data, num_fields, hash, tfm);
 
         ima_free_tfm(tfm);
 
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 414862e1904b..d47a7c86a21d 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -110,6 +110,7 @@ void ima_putc(struct seq_file *m, void *data, int datalen)
  *       char[20]=template digest
  *       32bit-le=template name size
  *       char[n]=template name
+ *       [eventdata length]
  *       eventdata[n]=template specific data
  */
 static int ima_measurements_show(struct seq_file *m, void *v)
@@ -119,6 +120,7 @@ static int ima_measurements_show(struct seq_file *m, void *v)
         struct ima_template_entry *e;
         int namelen;
         u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
+        int i;
 
         /* get entry */
         e = qe->entry;
@@ -136,15 +138,22 @@ static int ima_measurements_show(struct seq_file *m, void *v)
         ima_putc(m, e->digest, TPM_DIGEST_SIZE);
 
         /* 3rd: template name size */
-        namelen = strlen(e->template_name);
+        namelen = strlen(e->template_desc->name);
         ima_putc(m, &namelen, sizeof namelen);
 
         /* 4th:  template name */
-        ima_putc(m, (void *)e->template_name, namelen);
+        ima_putc(m, e->template_desc->name, namelen);
+
+        /* 5th:  template length (except for 'ima' template) */
+        if (strcmp(e->template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
+                ima_putc(m, &e->template_data_len,
+                         sizeof(e->template_data_len));
 
-        /* 5th:  template specific data */
-        ima_template_show(m, (struct ima_template_data *)&e->template,
-                          IMA_SHOW_BINARY);
+        /* 6th:  template specific data */
+        for (i = 0; i < e->template_desc->num_fields; i++) {
+                e->template_desc->fields[i]->field_show(m, IMA_SHOW_BINARY,
+                                                        &e->template_data[i]);
+        }
         return 0;
 }
 
@@ -175,33 +184,13 @@ void ima_print_digest(struct seq_file *m, u8 *digest, int size)
                 seq_printf(m, "%02x", *(digest + i));
 }
 
-void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show)
-{
-        struct ima_template_data *entry = e;
-        int namelen;
-
-        switch (show) {
-        case IMA_SHOW_ASCII:
-                ima_print_digest(m, entry->digest, IMA_DIGEST_SIZE);
-                seq_printf(m, " %s\n", entry->file_name);
-                break;
-        case IMA_SHOW_BINARY:
-                ima_putc(m, entry->digest, IMA_DIGEST_SIZE);
-
-                namelen = strlen(entry->file_name);
-                ima_putc(m, &namelen, sizeof namelen);
-                ima_putc(m, entry->file_name, namelen);
-        default:
-                break;
-        }
-}
-
 /* print in ascii */
 static int ima_ascii_measurements_show(struct seq_file *m, void *v)
 {
         /* the list never shrinks, so we don't need a lock here */
         struct ima_queue_entry *qe = v;
         struct ima_template_entry *e;
+        int i;
 
         /* get entry */
         e = qe->entry;
@@ -215,11 +204,18 @@ static int ima_ascii_measurements_show(struct seq_file *m, void *v)
         ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
 
         /* 3th:  template name */
-        seq_printf(m, " %s ", e->template_name);
+        seq_printf(m, " %s", e->template_desc->name);
 
         /* 4th:  template specific data */
-        ima_template_show(m, (struct ima_template_data *)&e->template,
-                          IMA_SHOW_ASCII);
+        for (i = 0; i < e->template_desc->num_fields; i++) {
+                seq_puts(m, " ");
+                if (e->template_data[i].len == 0)
+                        continue;
+
+                e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
+                                                        &e->template_data[i]);
+        }
+        seq_puts(m, "\n");
         return 0;
 }
 
diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index bf38d1af3cfd..1c4cf194592c 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -31,6 +31,20 @@ static struct ima_template_field supported_fields[] = {
          .field_show = ima_show_template_string},
 };
 
+static struct ima_template_desc *ima_template;
+
+static struct ima_template_desc *lookup_template_desc(const char *name)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(defined_templates); i++) {
+                if (strcmp(defined_templates[i].name, name) == 0)
+                        return defined_templates + i;
+        }
+
+        return NULL;
+}
+
 static struct ima_template_field *lookup_template_field(const char *field_id)
 {
         int i;
@@ -110,6 +124,14 @@ static int init_defined_templates(void)
         return result;
 }
 
+struct ima_template_desc *ima_template_desc_current(void)
+{
+        if (!ima_template)
+                ima_template = lookup_template_desc(IMA_TEMPLATE_IMA_NAME);
+
+        return ima_template;
+}
+
 int ima_init_template(void)
 {
         int result;