selinux: add selinuxfs structure for object class discovery
Christopher J. PeBenito [Wed, 23 May 2007 13:12:09 +0000 (09:12 -0400)]
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
security/selinux/selinuxfs.c

index 731a173..83bdd4d 100644 (file)
@@ -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;
index cf1acde..c9e92da 100644 (file)
@@ -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: