The kernel_read_file security hook is called prior to reading the file
into memory.
Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook at chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof at kernel.org>
Acked-by: Casey Schaufler <casey at schaufler-ca.com>
---
fs/exec.c | 4 ++++
include/linux/ima.h | 6 ++++++
include/linux/lsm_hooks.h | 8 ++++++++
include/linux/security.h | 7 +++++++
security/integrity/ima/ima_main.c | 16 ++++++++++++++++
security/security.c | 12 ++++++++++++
6 files changed, 53 insertions(+)
diff --git a/fs/exec.c b/fs/exec.c
index 67816a0..78dfdf3 100644
--- 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 7aea486..6adcaea 100644
--- 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 7d04a12..d32b7bd 100644
--- 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 cee1349..071fb74 100644
--- 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 bf53a70..80c24aa 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -338,6 +338,22 @@ int ima_module_check(struct file *file)
}
/**
+ * 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
* @buf: pointer to in memory file contents
diff --git a/security/security.c b/security/security.c
index 81a4c3a..1728fe2 100644
--- a/security/security.c
+++ b/security/security.c
@@ -899,6 +899,16 @@ 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);
+}
+
int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
enum kernel_read_file_id id)
{
@@ -1695,6 +1705,8 @@ 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 =
--
2.1.0
