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Subject[PATCH 04/11] selinux: add selinuxfs structure for object class discovery
From: Christopher J. PeBenito <cpebenito@tresys.com>

The structure is as follows (relative to selinuxfs root):

/class/file/index
/class/file/perms/read
/class/file/perms/write
...

Each class is allocated 33 inodes, 1 for the class index and 32 for
permissions. Relative to SEL_CLASS_INO_OFFSET, the inode of the index file
DIV 33 is the class number. The inode of the permission file % 33 is the
index of the permission for that class.

Signed-off-by: Christopher J. PeBenito <cpebenito@tresys.com>
Signed-off-by: James Morris <jmorris@namei.org>
---
security/selinux/include/security.h | 1 +
security/selinux/selinuxfs.c | 249 +++++++++++++++++++++++++++++++++++
2 files changed, 250 insertions(+), 0 deletions(-)
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index 731a173..83bdd4d 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -41,6 +41,7 @@ extern int selinux_mls_enabled;

int security_load_policy(void * data, size_t len);

+#define SEL_VEC_MAX 32
struct av_decision {
u32 allowed;
u32 decided;
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index cf1acde..c9e92da 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -67,6 +67,10 @@ static struct dentry *bool_dir = NULL;
static int bool_num = 0;
static int *bool_pending_values = NULL;

+/* global data for classes */
+static struct dentry *class_dir = NULL;
+static unsigned long last_class_ino;
+
extern void selnl_notify_setenforce(int val);

/* Check whether a task is allowed to use a security operation. */
@@ -106,6 +110,7 @@ static unsigned long sel_last_ino = SEL_INO_NEXT - 1;

#define SEL_INITCON_INO_OFFSET 0x01000000
#define SEL_BOOL_INO_OFFSET 0x02000000
+#define SEL_CLASS_INO_OFFSET 0x04000000
#define SEL_INO_MASK 0x00ffffff

#define TMPBUFLEN 12
@@ -237,6 +242,11 @@ static const struct file_operations sel_policyvers_ops = {

/* declaration for sel_write_load */
static int sel_make_bools(void);
+static int sel_make_classes(void);
+
+/* declaration for sel_make_class_dirs */
+static int sel_make_dir(struct inode *dir, struct dentry *dentry,
+ unsigned long *ino);

static ssize_t sel_read_mls(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
@@ -287,10 +297,18 @@ static ssize_t sel_write_load(struct file * file, const char __user * buf,
goto out;

ret = sel_make_bools();
+ if (ret) {
+ length = ret;
+ goto out1;
+ }
+
+ ret = sel_make_classes();
if (ret)
length = ret;
else
length = count;
+
+out1:
audit_log(current->audit_context, GFP_KERNEL, AUDIT_MAC_POLICY_LOAD,
"policy loaded auid=%u",
audit_get_loginuid(current->audit_context));
@@ -1293,6 +1311,225 @@ out:
return ret;
}

+static inline unsigned int sel_div(unsigned long a, unsigned long b)
+{
+ return a / b - (a % b < 0);
+}
+
+static inline unsigned long sel_class_to_ino(u16 class)
+{
+ return (class * (SEL_VEC_MAX + 1)) | SEL_CLASS_INO_OFFSET;
+}
+
+static inline u16 sel_ino_to_class(unsigned long ino)
+{
+ return sel_div(ino & SEL_INO_MASK, SEL_VEC_MAX + 1);
+}
+
+static inline unsigned long sel_perm_to_ino(u16 class, u32 perm)
+{
+ return (class * (SEL_VEC_MAX + 1) + perm) | SEL_CLASS_INO_OFFSET;
+}
+
+static inline u32 sel_ino_to_perm(unsigned long ino)
+{
+ return (ino & SEL_INO_MASK) % (SEL_VEC_MAX + 1);
+}
+
+static ssize_t sel_read_class(struct file * file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ ssize_t rc, len;
+ char *page;
+ unsigned long ino = file->f_path.dentry->d_inode->i_ino;
+
+ page = (char *)__get_free_page(GFP_KERNEL);
+ if (!page) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ len = snprintf(page, PAGE_SIZE, "%d", sel_ino_to_class(ino));
+ rc = simple_read_from_buffer(buf, count, ppos, page, len);
+ free_page((unsigned long)page);
+out:
+ return rc;
+}
+
+static const struct file_operations sel_class_ops = {
+ .read = sel_read_class,
+};
+
+static ssize_t sel_read_perm(struct file * file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ ssize_t rc, len;
+ char *page;
+ unsigned long ino = file->f_path.dentry->d_inode->i_ino;
+
+ page = (char *)__get_free_page(GFP_KERNEL);
+ if (!page) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ len = snprintf(page, PAGE_SIZE,"%d", sel_ino_to_perm(ino));
+ rc = simple_read_from_buffer(buf, count, ppos, page, len);
+ free_page((unsigned long)page);
+out:
+ return rc;
+}
+
+static const struct file_operations sel_perm_ops = {
+ .read = sel_read_perm,
+};
+
+static int sel_make_perm_files(char *objclass, int classvalue,
+ struct dentry *dir)
+{
+ int i, rc = 0, nperms;
+ char **perms;
+
+ rc = security_get_permissions(objclass, &perms, &nperms);
+ if (rc)
+ goto out;
+
+ for (i = 0; i < nperms; i++) {
+ struct inode *inode;
+ struct dentry *dentry;
+
+ dentry = d_alloc_name(dir, perms[i]);
+ if (!dentry) {
+ rc = -ENOMEM;
+ goto out1;
+ }
+
+ inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
+ if (!inode) {
+ rc = -ENOMEM;
+ goto out1;
+ }
+ inode->i_fop = &sel_perm_ops;
+ /* i+1 since perm values are 1-indexed */
+ inode->i_ino = sel_perm_to_ino(classvalue, i+1);
+ d_add(dentry, inode);
+ }
+
+out1:
+ for (i = 0; i < nperms; i++)
+ kfree(perms[i]);
+ kfree(perms);
+out:
+ return rc;
+}
+
+static int sel_make_class_dir_entries(char *classname, int index,
+ struct dentry *dir)
+{
+ struct dentry *dentry = NULL;
+ struct inode *inode = NULL;
+ int rc;
+
+ dentry = d_alloc_name(dir, "index");
+ if (!dentry) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ inode = sel_make_inode(dir->d_sb, S_IFREG|S_IRUGO);
+ if (!inode) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ inode->i_fop = &sel_class_ops;
+ inode->i_ino = sel_class_to_ino(index);
+ d_add(dentry, inode);
+
+ dentry = d_alloc_name(dir, "perms");
+ if (!dentry) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ rc = sel_make_dir(dir->d_inode, dentry, &last_class_ino);
+ if (rc)
+ goto out;
+
+ rc = sel_make_perm_files(classname, index, dentry);
+
+out:
+ return rc;
+}
+
+static void sel_remove_classes(void)
+{
+ struct list_head *class_node;
+
+ list_for_each(class_node, &class_dir->d_subdirs) {
+ struct dentry *class_subdir = list_entry(class_node,
+ struct dentry, d_u.d_child);
+ struct list_head *class_subdir_node;
+
+ list_for_each(class_subdir_node, &class_subdir->d_subdirs) {
+ struct dentry *d = list_entry(class_subdir_node,
+ struct dentry, d_u.d_child);
+
+ if (d->d_inode)
+ if (d->d_inode->i_mode & S_IFDIR)
+ sel_remove_entries(d);
+ }
+
+ sel_remove_entries(class_subdir);
+ }
+
+ sel_remove_entries(class_dir);
+}
+
+static int sel_make_classes(void)
+{
+ int rc = 0, nclasses, i;
+ char **classes;
+
+ /* delete any existing entries */
+ sel_remove_classes();
+
+ rc = security_get_classes(&classes, &nclasses);
+ if (rc < 0)
+ goto out;
+
+ /* +2 since classes are 1-indexed */
+ last_class_ino = sel_class_to_ino(nclasses+2);
+
+ for (i = 0; i < nclasses; i++) {
+ struct dentry *class_name_dir;
+
+ class_name_dir = d_alloc_name(class_dir, classes[i]);
+ if (!class_name_dir) {
+ rc = -ENOMEM;
+ goto out1;
+ }
+
+ rc = sel_make_dir(class_dir->d_inode, class_name_dir,
+ &last_class_ino);
+ if (rc)
+ goto out1;
+
+ /* i+1 since class values are 1-indexed */
+ rc = sel_make_class_dir_entries(classes[i], i+1,
+ class_name_dir);
+ if (rc)
+ goto out1;
+ }
+
+out1:
+ for (i = 0; i < nclasses; i++)
+ kfree(classes[i]);
+ kfree(classes);
+out:
+ return rc;
+}
+
static int sel_make_dir(struct inode *dir, struct dentry *dentry,
unsigned long *ino)
{
@@ -1407,6 +1644,18 @@ static int sel_fill_super(struct super_block * sb, void * data, int silent)
if (ret)
goto err;

+ dentry = d_alloc_name(sb->s_root, "class");
+ if (!dentry) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ ret = sel_make_dir(root_inode, dentry, &sel_last_ino);
+ if (ret)
+ goto err;
+
+ class_dir = dentry;
+
out:
return ret;
err:
--
1.5.0.6
-
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