security: define kernel_read_file hook

The kernel_read_file security hook is called prior to reading the file
into memory.

Changelog v4+:
- export security_kernel_read_file()

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>

diff --git a/fs/exec.c b/fs/exec.c
index 64cb3bc788c188afa542ea50df0eef52a78097fc..8aaa38666119e17a974c8b8e4b89aea8fa776564 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -842,6 +842,10 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
        if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
                return -EINVAL;
 
+       ret = security_kernel_read_file(file, id);
+       if (ret)
+               return ret;
+
        i_size = i_size_read(file_inode(file));
        if (max_size > 0 && i_size > max_size)
                return -EFBIG;

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 7aea4863c2442daac70141d2313024e7c0136739..6adcaea8101c1e28ae2616057d38f59ce381a570 100644 (file)
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -19,6 +19,7 @@ extern int ima_file_check(struct file *file, int mask, int opened);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
 extern int ima_module_check(struct file *file);
+extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
 extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
                              enum kernel_read_file_id id);
 
@@ -48,6 +49,11 @@ static inline int ima_module_check(struct file *file)
        return 0;
 }
 
+static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
+{
+       return 0;
+}
+
 static inline int ima_post_read_file(struct file *file, void *buf, loff_t size,
                                     enum kernel_read_file_id id)
 {

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 7d04a1220223424e4c9744d313c08c6b3af1487e..d32b7bd136353beaba7e0678ddcf3b7cfe16e29a 100644 (file)
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -552,6 +552,12 @@
  *     the kernel module to load. If the module is being loaded from a blob,
  *     this argument will be NULL.
  *     Return 0 if permission is granted.
+ * @kernel_read_file:
+ *     Read a file specified by userspace.
+ *     @file contains the file structure pointing to the file being read
+ *     by the kernel.
+ *     @id kernel read file identifier
+ *     Return 0 if permission is granted.
  * @kernel_post_read_file:
  *     Read a file specified by userspace.
  *     @file contains the file structure pointing to the file being read
@@ -1455,6 +1461,7 @@ union security_list_options {
        int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
        int (*kernel_module_request)(char *kmod_name);
        int (*kernel_module_from_file)(struct file *file);
+       int (*kernel_read_file)(struct file *file, enum kernel_read_file_id id);
        int (*kernel_post_read_file)(struct file *file, char *buf, loff_t size,
                                     enum kernel_read_file_id id);
        int (*task_fix_setuid)(struct cred *new, const struct cred *old,
@@ -1715,6 +1722,7 @@ struct security_hook_heads {
        struct list_head cred_transfer;
        struct list_head kernel_act_as;
        struct list_head kernel_create_files_as;
+       struct list_head kernel_read_file;
        struct list_head kernel_post_read_file;
        struct list_head kernel_module_request;
        struct list_head kernel_module_from_file;

diff --git a/include/linux/security.h b/include/linux/security.h
index cee1349e1155da03158d1e67e5541c391287c7da..071fb747fdbbdd00a925ec71e29833012d8c5d5a 100644 (file)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -302,6 +302,7 @@ int security_kernel_act_as(struct cred *new, u32 secid);
 int security_kernel_create_files_as(struct cred *new, struct inode *inode);
 int security_kernel_module_request(char *kmod_name);
 int security_kernel_module_from_file(struct file *file);
+int security_kernel_read_file(struct file *file, enum kernel_read_file_id id);
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
                                   enum kernel_read_file_id id);
 int security_task_fix_setuid(struct cred *new, const struct cred *old,
@@ -863,6 +864,12 @@ static inline int security_kernel_module_from_file(struct file *file)
        return 0;
 }
 
+static inline int security_kernel_read_file(struct file *file,
+                                           enum kernel_read_file_id id)
+{
+       return 0;
+}
+
 static inline int security_kernel_post_read_file(struct file *file,
                                                 char *buf, loff_t size,
                                                 enum kernel_read_file_id id)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index e9651be17b727b7a160a9e88b23555e4cf83162f..bbb80df28fb1a95baa6e01090f8a2dffe6c21e89 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -337,6 +337,22 @@ int ima_module_check(struct file *file)
        return process_measurement(file, NULL, 0, MAY_EXEC, MODULE_CHECK, 0);
 }
 
+/**
+ * ima_read_file - pre-measure/appraise hook decision based on policy
+ * @file: pointer to the file to be measured/appraised/audit
+ * @read_id: caller identifier
+ *
+ * Permit reading a file based on policy. The policy rules are written
+ * in terms of the policy identifier.  Appraising the integrity of
+ * a file requires a file descriptor.
+ *
+ * For permission return 0, otherwise return -EACCES.
+ */
+int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
+{
+       return 0;
+}
+
 /**
  * ima_post_read_file - in memory collect/appraise/audit measurement
  * @file: pointer to the file to be measured/appraised/audit

diff --git a/security/security.c b/security/security.c
index cd85be61c416426bcc5cd5a31b3b5af86872cef4..8e699f98a600812ef6a5b835b081e1f95d4f8b36 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -899,6 +899,17 @@ int security_kernel_module_from_file(struct file *file)
        return ima_module_check(file);
 }
 
+int security_kernel_read_file(struct file *file, enum kernel_read_file_id id)
+{
+       int ret;
+
+       ret = call_int_hook(kernel_read_file, 0, file, id);
+       if (ret)
+               return ret;
+       return ima_read_file(file, id);
+}
+EXPORT_SYMBOL_GPL(security_kernel_read_file);
+
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
                                   enum kernel_read_file_id id)
 {
@@ -1696,6 +1707,8 @@ struct security_hook_heads security_hook_heads = {
                LIST_HEAD_INIT(security_hook_heads.kernel_module_request),
        .kernel_module_from_file =
                LIST_HEAD_INIT(security_hook_heads.kernel_module_from_file),
+       .kernel_read_file =
+               LIST_HEAD_INIT(security_hook_heads.kernel_read_file),
        .kernel_post_read_file =
                LIST_HEAD_INIT(security_hook_heads.kernel_post_read_file),
        .task_fix_setuid =