ima: define a new hook to measure and appraise a file already in memory

This patch defines a new IMA hook ima_post_read_file() for measuring
and appraising files read by the kernel. The caller loads the file into
memory before calling this function, which calculates the hash followed by
the normal IMA policy based processing.

Changelog v5:
- fail ima_post_read_file() if either file or buf is NULL
v3:
- rename ima_hash_and_process_file() to ima_post_read_file()

v1:
- split patch

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>

5 files changed, 46 insertions, 12 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 2c5262f2823f..0b7134c04165 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -19,6 +19,7 @@
 
 #include <linux/types.h>
 #include <linux/crypto.h>
+#include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/hash.h>
 #include <linux/tpm.h>
@@ -152,7 +153,8 @@ enum ima_hooks {
 int ima_get_action(struct inode *inode, int mask, enum ima_hooks func);
 int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func);
 int ima_collect_measurement(struct integrity_iint_cache *iint,
-                            struct file *file, enum hash_algo algo);
+                            struct file *file, void *buf, loff_t size,
+                            enum hash_algo algo);
 void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
                            const unsigned char *filename,
                            struct evm_ima_xattr_data *xattr_value,
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 8750254506a9..370e42dfc5c5 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -188,7 +188,8 @@ int ima_get_action(struct inode *inode, int mask, enum ima_hooks func)
  * Return 0 on success, error code otherwise
  */
 int ima_collect_measurement(struct integrity_iint_cache *iint,
-                            struct file *file, enum hash_algo algo)
+                            struct file *file, void *buf, loff_t size,
+                            enum hash_algo algo)
 {
         const char *audit_cause = "failed";
         struct inode *inode = file_inode(file);
@@ -210,7 +211,8 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
 
                 hash.hdr.algo = algo;
 
-                result = ima_calc_file_hash(file, &hash.hdr);
+                result = (!buf) ?  ima_calc_file_hash(file, &hash.hdr) :
+                        ima_calc_buffer_hash(buf, size, &hash.hdr);
                 if (!result) {
                         int length = sizeof(hash.hdr) + hash.hdr.length;
                         void *tmpbuf = krealloc(iint->ima_hash, length,
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 288844908788..cb0d0ff1137b 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -300,7 +300,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
         if (iint->flags & IMA_DIGSIG)
                 return;
 
-        rc = ima_collect_measurement(iint, file, ima_hash_algo);
+        rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo);
         if (rc < 0)
                 return;
 
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 1be99a27a7f3..757765354158 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -153,8 +153,8 @@ void ima_file_free(struct file *file)
         ima_check_last_writer(iint, inode, file);
 }
 
-static int process_measurement(struct file *file, int mask,
-                               enum ima_hooks func, int opened)
+static int process_measurement(struct file *file, char *buf, loff_t size,
+                               int mask, enum ima_hooks func, int opened)
 {
         struct inode *inode = file_inode(file);
         struct integrity_iint_cache *iint = NULL;
@@ -226,7 +226,7 @@ static int process_measurement(struct file *file, int mask,
 
         hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 
-        rc = ima_collect_measurement(iint, file, hash_algo);
+        rc = ima_collect_measurement(iint, file, buf, size, hash_algo);
         if (rc != 0) {
                 if (file->f_flags & O_DIRECT)
                         rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES;
@@ -273,7 +273,8 @@ out:
 int ima_file_mmap(struct file *file, unsigned long prot)
 {
         if (file && (prot & PROT_EXEC))
-                return process_measurement(file, MAY_EXEC, MMAP_CHECK, 0);
+                return process_measurement(file, NULL, 0, MAY_EXEC,
+                                           MMAP_CHECK, 0);
         return 0;
 }
 
@@ -292,7 +293,8 @@ int ima_file_mmap(struct file *file, unsigned long prot)
  */
 int ima_bprm_check(struct linux_binprm *bprm)
 {
-        return process_measurement(bprm->file, MAY_EXEC, BPRM_CHECK, 0);
+        return process_measurement(bprm->file, NULL, 0, MAY_EXEC,
+                                   BPRM_CHECK, 0);
 }
 
 /**
@@ -307,7 +309,7 @@ int ima_bprm_check(struct linux_binprm *bprm)
  */
 int ima_file_check(struct file *file, int mask, int opened)
 {
-        return process_measurement(file,
+        return process_measurement(file, NULL, 0,
                                    mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
                                    FILE_CHECK, opened);
 }
@@ -332,7 +334,7 @@ int ima_module_check(struct file *file)
 #endif
                 return 0;       /* We rely on module signature checking */
         }
-        return process_measurement(file, MAY_EXEC, MODULE_CHECK, 0);
+        return process_measurement(file, NULL, 0, MAY_EXEC, MODULE_CHECK, 0);
 }
 
 int ima_fw_from_file(struct file *file, char *buf, size_t size)
@@ -343,7 +345,34 @@ int ima_fw_from_file(struct file *file, char *buf, size_t size)
                         return -EACCES; /* INTEGRITY_UNKNOWN */
                 return 0;
         }
-        return process_measurement(file, MAY_EXEC, FIRMWARE_CHECK, 0);
+        return process_measurement(file, NULL, 0, MAY_EXEC, FIRMWARE_CHECK, 0);
+}
+
+/**
+ * ima_post_read_file - in memory collect/appraise/audit measurement
+ * @file: pointer to the file to be measured/appraised/audit
+ * @buf: pointer to in memory file contents
+ * @size: size of in memory file contents
+ * @read_id: caller identifier
+ *
+ * Measure/appraise/audit in memory file based on policy.  Policy rules
+ * are written in terms of a policy identifier.
+ *
+ * On success return 0.  On integrity appraisal error, assuming the file
+ * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
+ */
+int ima_post_read_file(struct file *file, void *buf, loff_t size,
+                       enum kernel_read_file_id read_id)
+{
+        enum ima_hooks func = FILE_CHECK;
+
+        if (!file || !buf || size == 0) { /* should never happen */
+                if (ima_appraise & IMA_APPRAISE_ENFORCE)
+                        return -EACCES;
+                return 0;
+        }
+
+        return process_measurement(file, buf, size, MAY_READ, func, 0);
 }
 
 static int __init init_ima(void)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index b089ebef6648..cfbe86f476d0 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -12,6 +12,7 @@
  */
 #include <linux/module.h>
 #include <linux/list.h>
+#include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/magic.h>
 #include <linux/parser.h>