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Message-Id: <1497544976-7856-3-git-send-email-s.mesoraca16@gmail.com>
Date: Thu, 15 Jun 2017 18:42:49 +0200
From: Salvatore Mesoraca <s.mesoraca16@...il.com>
To: linux-kernel@...r.kernel.org
Cc: linux-security-module@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Salvatore Mesoraca <s.mesoraca16@...il.com>,
Brad Spengler <spender@...ecurity.net>,
PaX Team <pageexec@...email.hu>,
Casey Schaufler <casey@...aufler-ca.com>,
Kees Cook <keescook@...omium.org>,
James Morris <james.l.morris@...cle.com>,
"Serge E. Hallyn" <serge@...lyn.com>,
linux-mm@...ck.org,
x86@...nel.org,
Jann Horn <jannh@...gle.com>,
Christoph Hellwig <hch@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>
Subject: [RFC v2 2/9] S.A.R.A. framework creation
Initial S.A.R.A. framework setup.
Creation of a simplified interface to securityfs API to store and retrieve
configurations and flags from user-space.
Creation of some generic functions and macros to handle concurrent access
to configurations, memory allocation and path resolution.
Signed-off-by: Salvatore Mesoraca <s.mesoraca16@...il.com>
---
include/linux/lsm_hooks.h | 5 +
security/Kconfig | 1 +
security/Makefile | 2 +
security/sara/Kconfig | 42 +++
security/sara/Makefile | 3 +
security/sara/include/sara.h | 29 ++
security/sara/include/securityfs.h | 59 ++++
security/sara/include/utils.h | 69 +++++
security/sara/main.c | 95 +++++++
security/sara/securityfs.c | 560 +++++++++++++++++++++++++++++++++++++
security/sara/utils.c | 151 ++++++++++
security/security.c | 1 +
12 files changed, 1017 insertions(+)
create mode 100644 security/sara/Kconfig
create mode 100644 security/sara/Makefile
create mode 100644 security/sara/include/sara.h
create mode 100644 security/sara/include/securityfs.h
create mode 100644 security/sara/include/utils.h
create mode 100644 security/sara/main.c
create mode 100644 security/sara/securityfs.c
create mode 100644 security/sara/utils.c
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 080f34e..bd274db 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1946,5 +1946,10 @@ static inline void __init yama_add_hooks(void) { }
#else
static inline void loadpin_add_hooks(void) { };
#endif
+#ifdef CONFIG_SECURITY_SARA
+void __init sara_init(void);
+#else
+static inline void __init sara_init(void) { };
+#endif
#endif /* ! __LINUX_LSM_HOOKS_H */
diff --git a/security/Kconfig b/security/Kconfig
index 93027fd..1c13545 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -195,6 +195,7 @@ source security/tomoyo/Kconfig
source security/apparmor/Kconfig
source security/loadpin/Kconfig
source security/yama/Kconfig
+source security/sara/Kconfig
source security/integrity/Kconfig
diff --git a/security/Makefile b/security/Makefile
index f2d71cd..5d3578e 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -9,6 +9,7 @@ subdir-$(CONFIG_SECURITY_TOMOYO) += tomoyo
subdir-$(CONFIG_SECURITY_APPARMOR) += apparmor
subdir-$(CONFIG_SECURITY_YAMA) += yama
subdir-$(CONFIG_SECURITY_LOADPIN) += loadpin
+subdir-$(CONFIG_SECURITY_SARA) += sara
# always enable default capabilities
obj-y += commoncap.o
@@ -24,6 +25,7 @@ obj-$(CONFIG_SECURITY_TOMOYO) += tomoyo/
obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/
obj-$(CONFIG_SECURITY_YAMA) += yama/
obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/
+obj-$(CONFIG_SECURITY_SARA) += sara/
obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o
# Object integrity file lists
diff --git a/security/sara/Kconfig b/security/sara/Kconfig
new file mode 100644
index 0000000..5b61020
--- /dev/null
+++ b/security/sara/Kconfig
@@ -0,0 +1,42 @@
+menu S.A.R.A.
+
+config SECURITY_SARA
+ bool "Enable S.A.R.A."
+ depends on SECURITY
+ select SECURITYFS
+ default n
+ help
+ This selects S.A.R.A. LSM which aims to collect heterogeneous
+ security measures providing a common interface to manage them.
+ This LSM will always be stacked with the selected primary LSM and
+ other stacked LSMs.
+ Further information can be found in Documentation/security/SARA.rst.
+
+ If unsure, answer N.
+
+config SECURITY_SARA_DEFAULT_DISABLED
+ bool "S.A.R.A. will be disabled at boot."
+ depends on SECURITY_SARA
+ default n
+ help
+ If you say Y here, S.A.R.A. will not be enabled at startup. You can
+ override this option at boot time via "sara=[1|0]" kernel parameter
+ or via user-space utilities.
+ This option is useful for distro kernels.
+
+ If unsure, answer N.
+
+config SECURITY_SARA_NO_RUNTIME_ENABLE
+ bool "S.A.R.A. can be turn on only at boot time."
+ depends on SECURITY_SARA_DEFAULT_DISABLED
+ default y
+ help
+ By enabling this option it won't be possible to turn on S.A.R.A.
+ at runtime via user-space utilities. However it can still be
+ turned on at boot time via the "sara=1" kernel parameter.
+ This option is functionally equivalent to "sara=0" kernel parameter.
+ This option is useful for distro kernels.
+
+ If unsure, answer Y.
+
+endmenu
diff --git a/security/sara/Makefile b/security/sara/Makefile
new file mode 100644
index 0000000..8acd291
--- /dev/null
+++ b/security/sara/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_SECURITY_SARA) := sara.o
+
+sara-y := main.o securityfs.o utils.o
diff --git a/security/sara/include/sara.h b/security/sara/include/sara.h
new file mode 100644
index 0000000..1001a8a
--- /dev/null
+++ b/security/sara/include/sara.h
@@ -0,0 +1,29 @@
+/*
+ * S.A.R.A. Linux Security Module
+ *
+ * Copyright (C) 2017 Salvatore Mesoraca <s.mesoraca16@...il.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __SARA_H
+#define __SARA_H
+
+#include <linux/types.h>
+#include <uapi/linux/limits.h>
+
+#define SARA_VERSION 0
+#define SARA_PATH_MAX PATH_MAX
+
+#undef pr_fmt
+#define pr_fmt(fmt) "SARA: " fmt
+
+extern bool sara_config_locked __read_mostly;
+extern bool sara_enabled __read_mostly;
+
+void sara_init(void) __init;
+
+#endif /* __SARA_H */
diff --git a/security/sara/include/securityfs.h b/security/sara/include/securityfs.h
new file mode 100644
index 0000000..57e6306
--- /dev/null
+++ b/security/sara/include/securityfs.h
@@ -0,0 +1,59 @@
+/*
+ * S.A.R.A. Linux Security Module
+ *
+ * Copyright (C) 2017 Salvatore Mesoraca <s.mesoraca16@...il.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __SARA_SECURITYFS_H
+#define __SARA_SECURITYFS_H
+
+#include <linux/init.h>
+
+#define SARA_SUBTREE_NN_LEN 24
+#define SARA_CONFIG_HASH_LEN 20
+
+struct sara_secfs_node;
+
+int sara_secfs_init(void) __init;
+int sara_secfs_subtree_register(const char *subtree_name,
+ const struct sara_secfs_node *nodes,
+ size_t size) __init;
+
+enum sara_secfs_node_type {
+ SARA_SECFS_BOOL,
+ SARA_SECFS_READONLY_INT,
+ SARA_SECFS_CONFIG_LOAD,
+ SARA_SECFS_CONFIG_DUMP,
+ SARA_SECFS_CONFIG_HASH,
+};
+
+struct sara_secfs_node {
+ const enum sara_secfs_node_type type;
+ void *const data;
+ const size_t dir_contents_len;
+ const char name[SARA_SUBTREE_NN_LEN];
+};
+
+struct sara_secfs_fptrs {
+ int (*const load)(const char *, size_t);
+ ssize_t (*const dump)(char **);
+ int (*const hash)(char **);
+};
+
+struct sara_secfs_bool_flag {
+ const char notice_line[SARA_SUBTREE_NN_LEN];
+ bool *const flag;
+};
+
+#define DEFINE_SARA_SECFS_BOOL_FLAG(NAME, VAR) \
+const struct sara_secfs_bool_flag NAME = { \
+ .notice_line = #VAR, \
+ .flag = &VAR, \
+}
+
+#endif /* __SARA_SECURITYFS_H */
diff --git a/security/sara/include/utils.h b/security/sara/include/utils.h
new file mode 100644
index 0000000..166b9ed
--- /dev/null
+++ b/security/sara/include/utils.h
@@ -0,0 +1,69 @@
+/*
+ * S.A.R.A. Linux Security Module
+ *
+ * Copyright (C) 2017 Salvatore Mesoraca <s.mesoraca16@...il.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#ifndef __SARA_UTILS_H
+#define __SARA_UTILS_H
+
+#include <linux/kref.h>
+#include <linux/rcupdate.h>
+#include <linux/spinlock.h>
+
+char *get_absolute_path(const struct path *spath, char **buf);
+char *get_current_path(char **buf);
+void *sara_kvmalloc(size_t size) __attribute__((malloc));
+void *sara_kvcalloc(size_t n, size_t size) __attribute__((malloc));
+
+static inline void release_entry(struct kref *ref)
+{
+ /* All work is done after the return from kref_put(). */
+}
+
+#define SARA_CONFIG_GET_RCU(DEST, CONFIG) do { \
+ rcu_read_lock(); \
+ DEST = rcu_dereference(CONFIG); \
+} while (0)
+
+#define SARA_CONFIG_PUT_RCU(DATA) do { \
+ rcu_read_unlock(); \
+ DATA = NULL; \
+} while (0)
+
+#define SARA_CONFIG_GET(DEST, CONFIG) do { \
+ rcu_read_lock(); \
+ do { \
+ DEST = rcu_dereference(CONFIG); \
+ } while (DEST && !kref_get_unless_zero(&DEST->refcount)); \
+ rcu_read_unlock(); \
+} while (0)
+
+#define SARA_CONFIG_PUT(DATA, FREE) do { \
+ if (kref_put(&DATA->refcount, release_entry)) { \
+ synchronize_rcu(); \
+ FREE(DATA); \
+ } \
+ DATA = NULL; \
+} while (0)
+
+#define SARA_CONFIG_REPLACE(CONFIG, NEW, FREE, LOCK) do { \
+ typeof(NEW) tmp; \
+ spin_lock(LOCK); \
+ tmp = rcu_dereference_protected(CONFIG, \
+ lockdep_is_held(LOCK)); \
+ rcu_assign_pointer(CONFIG, NEW); \
+ if (kref_put(&tmp->refcount, release_entry)) { \
+ spin_unlock(LOCK); \
+ synchronize_rcu(); \
+ FREE(tmp); \
+ } else \
+ spin_unlock(LOCK); \
+} while (0)
+
+#endif /* __SARA_UTILS_H */
diff --git a/security/sara/main.c b/security/sara/main.c
new file mode 100644
index 0000000..2007735
--- /dev/null
+++ b/security/sara/main.c
@@ -0,0 +1,95 @@
+/*
+ * S.A.R.A. Linux Security Module
+ *
+ * Copyright (C) 2017 Salvatore Mesoraca <s.mesoraca16@...il.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/printk.h>
+
+#include "include/sara.h"
+#include "include/securityfs.h"
+
+static const int sara_version = SARA_VERSION;
+
+#ifdef CONFIG_SECURITY_SARA_NO_RUNTIME_ENABLE
+bool sara_config_locked __read_mostly = true;
+#else
+bool sara_config_locked __read_mostly;
+#endif
+
+#ifdef CONFIG_SECURITY_SARA_DEFAULT_DISABLED
+bool sara_enabled __read_mostly;
+#else
+bool sara_enabled __read_mostly = true;
+#endif
+
+static DEFINE_SARA_SECFS_BOOL_FLAG(sara_enabled_data, sara_enabled);
+static DEFINE_SARA_SECFS_BOOL_FLAG(sara_config_locked_data, sara_config_locked);
+
+static int __init sara_enabled_setup(char *str)
+{
+ if (str[0] == '1' && str[1] == '\0') {
+ sara_enabled = true;
+ sara_config_locked = false;
+ } else {
+ sara_enabled = false;
+ sara_config_locked = true;
+ }
+ return 1;
+}
+__setup("sara=", sara_enabled_setup);
+
+static const struct sara_secfs_node main_fs[] __initconst = {
+ {
+ .name = "enabled",
+ .type = SARA_SECFS_BOOL,
+ .data = (void *) &sara_enabled_data,
+ },
+ {
+ .name = "locked",
+ .type = SARA_SECFS_BOOL,
+ .data = (void *) &sara_config_locked_data,
+ },
+ {
+ .name = "version",
+ .type = SARA_SECFS_READONLY_INT,
+ .data = (int *) &sara_version,
+ },
+};
+
+void __init sara_init(void)
+{
+ if (!sara_enabled && sara_config_locked) {
+ pr_notice("permanently disabled.\n");
+ return;
+ }
+
+ pr_debug("initializing...\n");
+
+ if (sara_secfs_subtree_register("main",
+ main_fs,
+ ARRAY_SIZE(main_fs))) {
+ pr_crit("impossible to register main fs.\n");
+ goto error;
+ }
+
+ pr_debug("initialized.\n");
+
+ if (sara_enabled)
+ pr_info("enabled\n");
+ else
+ pr_notice("disabled\n");
+ return;
+
+error:
+ sara_enabled = false;
+ sara_config_locked = true;
+ pr_crit("permanently disabled.\n");
+}
diff --git a/security/sara/securityfs.c b/security/sara/securityfs.c
new file mode 100644
index 0000000..d493245
--- /dev/null
+++ b/security/sara/securityfs.c
@@ -0,0 +1,560 @@
+/*
+ * S.A.R.A. Linux Security Module
+ *
+ * Copyright (C) 2017 Salvatore Mesoraca <s.mesoraca16@...il.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/capability.h>
+#include <linux/ctype.h>
+#include <linux/mm.h>
+#include <linux/printk.h>
+#include <linux/security.h>
+#include <linux/seq_file.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+
+#include "include/sara.h"
+#include "include/utils.h"
+#include "include/securityfs.h"
+
+#define __SARA_STR_HELPER(x) #x
+#define SARA_STR(x) __SARA_STR_HELPER(x)
+
+static struct dentry *fs_root;
+
+static inline bool check_config_write_access(void)
+{
+ if (unlikely(sara_config_locked && !capable(CAP_MAC_ADMIN))) {
+ pr_warn("config write access blocked.\n");
+ return false;
+ }
+ return true;
+}
+
+static bool check_config_access(const struct file *file)
+{
+ if (file->f_flags & O_WRONLY || file->f_flags & O_RDWR)
+ if (unlikely(!check_config_write_access()))
+ return false;
+ return true;
+}
+
+static int file_flag_show(struct seq_file *seq, void *v)
+{
+ bool *flag = ((struct sara_secfs_bool_flag *)seq->private)->flag;
+
+ seq_printf(seq, "%d\n", *flag);
+ return 0;
+}
+
+static ssize_t file_flag_write(struct file *file,
+ const char __user *ubuf,
+ size_t buf_size,
+ loff_t *offset)
+{
+ struct sara_secfs_bool_flag *bool_flag =
+ ((struct seq_file *) file->private_data)->private;
+ char kbuf[2] = {'A', '\n'};
+ bool nf;
+
+ if (unlikely(*offset != 0))
+ return -ESPIPE;
+
+ if (unlikely(buf_size != 1 && buf_size != 2))
+ return -EPERM;
+
+ if (unlikely(copy_from_user(kbuf, ubuf, buf_size)))
+ return -EFAULT;
+
+ if (unlikely(kbuf[1] != '\n'))
+ return -EPERM;
+
+ switch (kbuf[0]) {
+ case '0':
+ nf = false;
+ break;
+ case '1':
+ nf = true;
+ break;
+ default:
+ return -EPERM;
+ }
+
+ *bool_flag->flag = nf;
+
+ if (strlen(bool_flag->notice_line) > 0)
+ pr_notice("flag \"%s\" set to %d\n",
+ bool_flag->notice_line,
+ nf);
+
+ return buf_size;
+}
+
+static int file_flag_open(struct inode *inode, struct file *file)
+{
+ if (unlikely(!check_config_access(file)))
+ return -EACCES;
+ return single_open(file, file_flag_show, inode->i_private);
+}
+
+static const struct file_operations file_flag = {
+ .owner = THIS_MODULE,
+ .open = file_flag_open,
+ .write = file_flag_write,
+ .read = seq_read,
+ .release = single_release,
+};
+
+static int file_readonly_int_show(struct seq_file *seq, void *v)
+{
+ int *flag = seq->private;
+
+ seq_printf(seq, "%d\n", *flag);
+ return 0;
+}
+
+static int file_readonly_int_open(struct inode *inode, struct file *file)
+{
+ if (unlikely(!check_config_access(file)))
+ return -EACCES;
+ return single_open(file, file_readonly_int_show, inode->i_private);
+}
+
+static const struct file_operations file_readonly_int = {
+ .owner = THIS_MODULE,
+ .open = file_readonly_int_open,
+ .read = seq_read,
+ .release = single_release,
+};
+
+static ssize_t file_config_loader_write(struct file *file,
+ const char __user *ubuf,
+ size_t buf_size,
+ loff_t *offset)
+{
+ const struct sara_secfs_fptrs *fptrs = file->private_data;
+ char *kbuf = NULL;
+ ssize_t ret;
+
+ ret = -ESPIPE;
+ if (unlikely(*offset != 0))
+ goto out;
+
+ ret = -ENOMEM;
+ kbuf = sara_kvmalloc(buf_size);
+ if (unlikely(kbuf == NULL))
+ goto out;
+
+ ret = -EFAULT;
+ if (unlikely(copy_from_user(kbuf, ubuf, buf_size)))
+ goto out;
+
+ ret = fptrs->load(kbuf, buf_size);
+
+ if (unlikely(ret))
+ goto out;
+
+ ret = buf_size;
+
+out:
+ kvfree(kbuf);
+ return ret;
+}
+
+static int file_config_loader_open(struct inode *inode, struct file *file)
+{
+ if (unlikely(!check_config_access(file)))
+ return -EACCES;
+ file->private_data = inode->i_private;
+ return 0;
+}
+
+static const struct file_operations file_config_loader = {
+ .owner = THIS_MODULE,
+ .open = file_config_loader_open,
+ .write = file_config_loader_write,
+};
+
+static int file_config_show(struct seq_file *seq, void *v)
+{
+ const struct sara_secfs_fptrs *fptrs = seq->private;
+ char *buf = NULL;
+ ssize_t ret;
+
+ ret = fptrs->dump(&buf);
+ if (unlikely(ret <= 0))
+ goto out;
+ seq_write(seq, buf, ret);
+ kvfree(buf);
+ ret = 0;
+out:
+ return ret;
+}
+
+static int file_dumper_open(struct inode *inode, struct file *file)
+{
+ if (unlikely(!check_config_access(file)))
+ return -EACCES;
+ return single_open(file, file_config_show, inode->i_private);
+}
+
+static const struct file_operations file_config_dumper = {
+ .owner = THIS_MODULE,
+ .open = file_dumper_open,
+ .read = seq_read,
+ .release = single_release,
+};
+
+static int file_hash_show(struct seq_file *seq, void *v)
+{
+ const struct sara_secfs_fptrs *fptrs = seq->private;
+ char *buf = NULL;
+ int ret;
+
+ ret = fptrs->hash(&buf);
+ if (unlikely(ret))
+ goto out;
+ seq_printf(seq, "%" SARA_STR(SARA_CONFIG_HASH_LEN) "phN\n", buf);
+ kvfree(buf);
+ ret = 0;
+out:
+ return ret;
+}
+
+static int file_hash_open(struct inode *inode, struct file *file)
+{
+ if (unlikely(!check_config_access(file)))
+ return -EACCES;
+ return single_open(file, file_hash_show, inode->i_private);
+}
+
+static const struct file_operations file_hash = {
+ .owner = THIS_MODULE,
+ .open = file_hash_open,
+ .read = seq_read,
+ .release = single_release,
+};
+
+static int mk_dir(struct dentry *parent,
+ const char *dir_name,
+ struct dentry **dir_out)
+{
+ int ret = 0;
+
+ *dir_out = securityfs_create_dir(dir_name, parent);
+ if (IS_ERR(*dir_out)) {
+ ret = -PTR_ERR(*dir_out);
+ *dir_out = NULL;
+ }
+ return ret;
+}
+
+static int mk_bool_flag(struct dentry *parent,
+ const char *file_name,
+ struct dentry **dir_out,
+ void *flag)
+{
+ int ret = 0;
+
+ *dir_out = securityfs_create_file(file_name,
+ 0600,
+ parent,
+ flag,
+ &file_flag);
+ if (IS_ERR(*dir_out)) {
+ ret = -PTR_ERR(*dir_out);
+ *dir_out = NULL;
+ }
+ return 0;
+}
+
+static int mk_readonly_int(struct dentry *parent,
+ const char *file_name,
+ struct dentry **dir_out,
+ void *readonly_int)
+{
+ int ret = 0;
+
+ *dir_out = securityfs_create_file(file_name,
+ 0400,
+ parent,
+ readonly_int,
+ &file_readonly_int);
+ if (IS_ERR(*dir_out)) {
+ ret = -PTR_ERR(*dir_out);
+ *dir_out = NULL;
+ }
+ return 0;
+}
+
+static int mk_config_loader(struct dentry *parent,
+ const char *file_name,
+ struct dentry **dir_out,
+ void *fptrs)
+{
+ int ret = 0;
+
+ *dir_out = securityfs_create_file(file_name,
+ 0200,
+ parent,
+ fptrs,
+ &file_config_loader);
+ if (IS_ERR(*dir_out)) {
+ ret = -PTR_ERR(*dir_out);
+ *dir_out = NULL;
+ }
+ return 0;
+}
+
+static int mk_config_dumper(struct dentry *parent,
+ const char *file_name,
+ struct dentry **dir_out,
+ void *fptrs)
+{
+ int ret = 0;
+
+ *dir_out = securityfs_create_file(file_name,
+ 0400,
+ parent,
+ fptrs,
+ &file_config_dumper);
+ if (IS_ERR(*dir_out)) {
+ ret = -PTR_ERR(*dir_out);
+ *dir_out = NULL;
+ }
+ return 0;
+}
+
+static int mk_config_hash(struct dentry *parent,
+ const char *file_name,
+ struct dentry **dir_out,
+ void *fptrs)
+{
+ int ret = 0;
+
+ *dir_out = securityfs_create_file(file_name,
+ 0400,
+ parent,
+ fptrs,
+ &file_hash);
+ if (IS_ERR(*dir_out)) {
+ ret = -PTR_ERR(*dir_out);
+ *dir_out = NULL;
+ }
+ return 0;
+}
+
+struct sara_secfs_subtree {
+ char name[SARA_SUBTREE_NN_LEN];
+ size_t size;
+ struct dentry **nodes;
+ const struct sara_secfs_node *nodes_description;
+ struct list_head subtree_list;
+};
+
+static LIST_HEAD(subtree_list);
+
+int __init sara_secfs_subtree_register(const char *subtree_name,
+ const struct sara_secfs_node *nodes,
+ size_t size)
+{
+ int ret;
+ struct sara_secfs_subtree *subtree = NULL;
+
+ ret = -EINVAL;
+ if (unlikely(size < 1))
+ goto error;
+ ret = -ENOMEM;
+ subtree = kmalloc(sizeof(*subtree), GFP_KERNEL);
+ if (unlikely(subtree == NULL))
+ goto error;
+ strncpy(subtree->name,
+ subtree_name,
+ sizeof(subtree->name));
+ subtree->size = size+1;
+ subtree->nodes = kcalloc(subtree->size,
+ sizeof(*subtree->nodes),
+ GFP_KERNEL);
+ if (unlikely(subtree->nodes == NULL))
+ goto error;
+ subtree->nodes_description = nodes;
+ INIT_LIST_HEAD(&subtree->subtree_list);
+ list_add(&subtree->subtree_list, &subtree_list);
+ return 0;
+
+error:
+ kfree(subtree);
+ pr_warn("SECFS: Impossible to register '%s' (%d).\n",
+ subtree_name, ret);
+ return ret;
+}
+
+static inline int __init create_node(enum sara_secfs_node_type type,
+ struct dentry *parent,
+ const char *name,
+ struct dentry **output,
+ void *data)
+{
+ switch (type) {
+ case SARA_SECFS_BOOL:
+ return mk_bool_flag(parent, name, output, data);
+ case SARA_SECFS_READONLY_INT:
+ return mk_readonly_int(parent, name, output, data);
+ case SARA_SECFS_CONFIG_LOAD:
+ return mk_config_loader(parent, name, output, data);
+ case SARA_SECFS_CONFIG_DUMP:
+ return mk_config_dumper(parent, name, output, data);
+ case SARA_SECFS_CONFIG_HASH:
+ return mk_config_hash(parent, name, output, data);
+ default:
+ return -EINVAL;
+ }
+}
+
+static void subtree_unplug(struct sara_secfs_subtree *subtree)
+{
+ int i;
+
+ for (i = 0; i < subtree->size; ++i) {
+ if (subtree->nodes[i] != NULL) {
+ securityfs_remove(subtree->nodes[i]);
+ subtree->nodes[i] = NULL;
+ }
+ }
+}
+
+static int __init subtree_plug(struct sara_secfs_subtree *subtree)
+{
+ int ret;
+ int i;
+ const struct sara_secfs_node *nodes = subtree->nodes_description;
+
+ ret = -EINVAL;
+ if (unlikely(fs_root == NULL))
+ goto out;
+ ret = mk_dir(fs_root,
+ subtree->name,
+ &subtree->nodes[subtree->size-1]);
+ if (unlikely(ret))
+ goto out_unplug;
+ for (i = 0; i < subtree->size-1; ++i) {
+ ret = create_node(nodes[i].type,
+ subtree->nodes[subtree->size-1],
+ nodes[i].name,
+ &subtree->nodes[i],
+ nodes[i].data);
+ if (unlikely(ret))
+ goto out_unplug;
+ }
+ return 0;
+
+out_unplug:
+ subtree_unplug(subtree);
+out:
+ pr_warn("SECFS: Impossible to plug '%s' (%d).\n", subtree->name, ret);
+ return ret;
+}
+
+static int __init subtree_plug_all(void)
+{
+ int ret;
+ struct list_head *position;
+ struct sara_secfs_subtree *subtree;
+
+ ret = -EINVAL;
+ if (unlikely(fs_root == NULL))
+ goto out;
+ ret = 0;
+ list_for_each(position, &subtree_list) {
+ subtree = list_entry(position,
+ struct sara_secfs_subtree,
+ subtree_list);
+ if (subtree->nodes[0] == NULL) {
+ ret = subtree_plug(subtree);
+ if (unlikely(ret))
+ goto out;
+ }
+ }
+out:
+ if (unlikely(ret))
+ pr_warn("SECFS: Impossible to plug subtrees (%d).\n", ret);
+ return ret;
+}
+
+static void __init subtree_free_all(bool unplug)
+{
+ struct list_head *position;
+ struct list_head *next;
+ struct sara_secfs_subtree *subtree;
+
+ list_for_each_safe(position, next, &subtree_list) {
+ subtree = list_entry(position,
+ struct sara_secfs_subtree,
+ subtree_list);
+ list_del(position);
+ if (unplug)
+ subtree_unplug(subtree);
+ kfree(subtree->nodes);
+ kfree(subtree);
+ }
+}
+
+static int mk_root(void)
+{
+ int ret = -1;
+
+ if (fs_root == NULL)
+ ret = mk_dir(NULL, "sara", &fs_root);
+ if (unlikely(ret || fs_root == NULL))
+ pr_warn("SECFS: Impossible to create root (%d).\n", ret);
+ return ret;
+}
+
+static inline void rm_root(void)
+{
+ if (likely(fs_root != NULL)) {
+ securityfs_remove(fs_root);
+ fs_root = NULL;
+ }
+}
+
+static inline void __init sara_secfs_destroy(void)
+{
+ subtree_free_all(true);
+ rm_root();
+}
+
+int __init sara_secfs_init(void)
+{
+ int ret;
+
+ if (!sara_enabled && sara_config_locked)
+ return 0;
+
+ fs_root = NULL;
+
+ ret = mk_root();
+ if (unlikely(ret))
+ goto error;
+
+ ret = subtree_plug_all();
+ if (unlikely(ret))
+ goto error;
+
+ subtree_free_all(false);
+
+ pr_debug("securityfs initilaized.\n");
+ return 0;
+
+error:
+ sara_secfs_destroy();
+ pr_crit("impossible to build securityfs.\n");
+ return ret;
+}
+
+fs_initcall(sara_secfs_init);
diff --git a/security/sara/utils.c b/security/sara/utils.c
new file mode 100644
index 0000000..9250b7b
--- /dev/null
+++ b/security/sara/utils.c
@@ -0,0 +1,151 @@
+/*
+ * S.A.R.A. Linux Security Module
+ *
+ * Copyright (C) 2017 Salvatore Mesoraca <s.mesoraca16@...il.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/dcache.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#include "include/sara.h"
+#include "include/utils.h"
+
+/**
+ * get_absolute_path - return the absolute path for a struct path
+ * @spath: the struct path to report
+ * @buf: double pointer where the newly allocated buffer will be placed
+ *
+ * Returns a pointer into @buf or an error code.
+ *
+ * The caller MUST kvfree @buf when finished using it.
+ */
+char *get_absolute_path(const struct path *spath, char **buf)
+{
+ size_t size = 128;
+ char *work_buf = NULL;
+ char *path = NULL;
+
+ do {
+ kvfree(work_buf);
+ work_buf = NULL;
+ if (size > SARA_PATH_MAX) {
+ path = ERR_PTR(-ENAMETOOLONG);
+ goto error;
+ }
+ work_buf = sara_kvmalloc(size);
+ if (unlikely(work_buf == NULL)) {
+ path = ERR_PTR(-ENOMEM);
+ goto error;
+ }
+ path = d_absolute_path(spath, work_buf, size);
+ size *= 2;
+ } while (PTR_ERR(path) == -ENAMETOOLONG);
+ if (!IS_ERR(path))
+ goto out;
+
+error:
+ kvfree(work_buf);
+ work_buf = NULL;
+out:
+ *buf = work_buf;
+ return path;
+}
+
+/**
+ * get_current_path - return the absolute path for the exe_file
+ * in the current task_struct, falling back
+ * to the contents of the comm field.
+ * @buf: double pointer where the newly allocated buffer will be placed
+ *
+ * Returns a pointer into @buf or an error code.
+ *
+ * The caller MUST kvfree @buf when finished using it.
+ */
+char *get_current_path(char **buf)
+{
+ struct file *exe_file;
+ char *path = NULL;
+
+ exe_file = get_task_exe_file(current);
+ if (exe_file) {
+ path = get_absolute_path(&exe_file->f_path, buf);
+ fput(exe_file);
+ }
+ if (IS_ERR_OR_NULL(path)) {
+ *buf = kzalloc(sizeof(current->comm), GFP_KERNEL);
+ get_task_comm(*buf, current);
+ path = *buf;
+ }
+ return path;
+}
+
+/**
+ * sara_kvmalloc - do allocation preferring kmalloc but falling back to vmalloc
+ * @size: how many bytes of memory are required
+ *
+ * Return: allocated buffer or NULL if failed
+ *
+ * It is possible that ruleset being loaded from the user is larger than
+ * what can be allocated by kmalloc, in those cases fall back to vmalloc.
+ *
+ * Nearly identical copy of AppArmor's __aa_kvmalloc.
+ */
+void *__attribute__((malloc)) sara_kvmalloc(size_t size)
+{
+ void *buffer = NULL;
+
+ __might_sleep(__FILE__, __LINE__, 0);
+
+ if (size == 0)
+ return NULL;
+
+ /* do not attempt kmalloc if we need more than 16 pages at once */
+ if (size <= (16*PAGE_SIZE))
+ buffer = kmalloc(size, GFP_KERNEL | __GFP_NORETRY |
+ __GFP_NOWARN);
+ if (!buffer)
+ buffer = vmalloc(size);
+
+ return buffer;
+}
+
+/**
+ * sara_kvcalloc - do allocation preferring kcalloc but falling back to vmalloc
+ * @size: number of object to allocate
+ * @size: how many bytes of memory are required per each object
+ *
+ * Return: allocated buffer or NULL if failed
+ *
+ * It is possible that ruleset being loaded from the user is larger than
+ * what can be allocated by kcalloc, in those cases fall back to vmalloc.
+ *
+ * Nearly identical copy of AppArmor's __aa_kvmalloc.
+ */
+void *__attribute__((malloc)) sara_kvcalloc(size_t n, size_t size)
+{
+ void *buffer = NULL;
+
+ __might_sleep(__FILE__, __LINE__, 0);
+
+ if (size == 0)
+ return NULL;
+
+ /* do not attempt kmalloc if we need more than 16 pages at once */
+ if (size <= (16*PAGE_SIZE))
+ buffer = kcalloc(n, size, GFP_KERNEL | __GFP_NORETRY |
+ __GFP_NOWARN);
+ if (!buffer)
+ buffer = vzalloc(n*size);
+
+ return buffer;
+}
diff --git a/security/security.c b/security/security.c
index b9fea39..42c8028 100644
--- a/security/security.c
+++ b/security/security.c
@@ -69,6 +69,7 @@ int __init security_init(void)
capability_add_hooks();
yama_add_hooks();
loadpin_add_hooks();
+ sara_init();
/*
* Load all the remaining security modules.
--
1.9.1
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