AppArmor: add initial "features" directory to securityfs

This adds the "features" subdirectory to the AppArmor securityfs
to display boolean features flags and the known capability mask.

Signed-off-by: Kees Cook <kees@ubuntu.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

2 files changed, 65 insertions, 0 deletions

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 1e22bb3a8851..f30dada0dca2 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -18,6 +18,7 @@
 #include <linux/seq_file.h>
 #include <linux/uaccess.h>
 #include <linux/namei.h>
+#include <linux/capability.h>
 
 #include "include/apparmor.h"
 #include "include/apparmorfs.h"
@@ -142,12 +143,62 @@ static const struct file_operations aa_fs_profile_remove = {
         .llseek = default_llseek,
 };
 
+static int aa_fs_seq_show(struct seq_file *seq, void *v)
+{
+        struct aa_fs_entry *fs_file = seq->private;
+
+        if (!fs_file)
+                return 0;
+
+        switch (fs_file->v_type) {
+        case AA_FS_TYPE_BOOLEAN:
+                seq_printf(seq, "%s\n", fs_file->v.boolean ? "yes" : "no");
+                break;
+        case AA_FS_TYPE_U64:
+                seq_printf(seq, "%#08lx\n", fs_file->v.u64);
+                break;
+        default:
+                /* Ignore unpritable entry types. */
+                break;
+        }
+
+        return 0;
+}
+
+static int aa_fs_seq_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, aa_fs_seq_show, inode->i_private);
+}
+
+const struct file_operations aa_fs_seq_file_ops = {
+        .owner          = THIS_MODULE,
+        .open           = aa_fs_seq_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
 /** Base file system setup **/
 
+static struct aa_fs_entry aa_fs_entry_domain[] = {
+        AA_FS_FILE_BOOLEAN("change_hat",        1),
+        AA_FS_FILE_BOOLEAN("change_hatv",       1),
+        AA_FS_FILE_BOOLEAN("change_onexec",     1),
+        AA_FS_FILE_BOOLEAN("change_profile",    1),
+        { }
+};
+
+static struct aa_fs_entry aa_fs_entry_features[] = {
+        AA_FS_DIR("domain",                     aa_fs_entry_domain),
+        AA_FS_FILE_U64("capability",            VFS_CAP_FLAGS_MASK),
+        { }
+};
+
 static struct aa_fs_entry aa_fs_entry_apparmor[] = {
         AA_FS_FILE_FOPS(".load", 0640, &aa_fs_profile_load),
         AA_FS_FILE_FOPS(".replace", 0640, &aa_fs_profile_replace),
         AA_FS_FILE_FOPS(".remove", 0640, &aa_fs_profile_remove),
+        AA_FS_DIR("features", aa_fs_entry_features),
         { }
 };
 
diff --git a/security/apparmor/include/apparmorfs.h b/security/apparmor/include/apparmorfs.h
index 4fdf02f26a3a..16e654530f30 100644
--- a/security/apparmor/include/apparmorfs.h
+++ b/security/apparmor/include/apparmorfs.h
@@ -16,6 +16,8 @@
 #define __AA_APPARMORFS_H
 
 enum aa_fs_type {
+        AA_FS_TYPE_BOOLEAN,
+        AA_FS_TYPE_U64,
         AA_FS_TYPE_FOPS,
         AA_FS_TYPE_DIR,
 };
@@ -28,11 +30,23 @@ struct aa_fs_entry {
         umode_t mode;
         enum aa_fs_type v_type;
         union {
+                bool boolean;
+                unsigned long u64;
                 struct aa_fs_entry *files;
         } v;
         const struct file_operations *file_ops;
 };
 
+extern const struct file_operations aa_fs_seq_file_ops;
+
+#define AA_FS_FILE_BOOLEAN(_name, _value) \
+        { .name = (_name), .mode = 0444, \
+          .v_type = AA_FS_TYPE_BOOLEAN, .v.boolean = (_value), \
+          .file_ops = &aa_fs_seq_file_ops }
+#define AA_FS_FILE_U64(_name, _value) \
+        { .name = (_name), .mode = 0444, \
+          .v_type = AA_FS_TYPE_U64, .v.u64 = (_value), \
+          .file_ops = &aa_fs_seq_file_ops }
 #define AA_FS_FILE_FOPS(_name, _mode, _fops) \
         { .name = (_name), .v_type = AA_FS_TYPE_FOPS, \
           .mode = (_mode), .file_ops = (_fops) }