apparmor: add custom apparmorfs that will be used by policy namespace files
AppArmor policy needs to be able to be resolved based on the policy namespace a task is confined by. Add a base apparmorfs filesystem that (like nsfs) will exist as a kern mount and be accessed via jump_link through a securityfs file. Setup the base apparmorfs fns and data, but don't use it yet. Signed-off-by: John Johansen <john.johansen@canonical.com> Reviewed-by: Seth Arnold <seth.arnold@canonical.com> Reviewed-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
John Johansen
parent
64c8697045
commit
a481f4d917
2 changed files with 338 additions and 17 deletions
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@ -80,6 +80,8 @@
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#define BTRFS_TEST_MAGIC 0x73727279
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#define NSFS_MAGIC 0x6e736673
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#define BPF_FS_MAGIC 0xcafe4a11
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#define AAFS_MAGIC 0x5a3c69f0
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/* Since UDF 2.01 is ISO 13346 based... */
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#define UDF_SUPER_MAGIC 0x15013346
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#define BALLOON_KVM_MAGIC 0x13661366
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@ -22,8 +22,9 @@
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#include <linux/namei.h>
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#include <linux/capability.h>
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#include <linux/rcupdate.h>
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#include <uapi/linux/major.h>
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#include <linux/fs.h>
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#include <uapi/linux/major.h>
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#include <uapi/linux/magic.h>
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#include "include/apparmor.h"
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#include "include/apparmorfs.h"
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@ -74,6 +75,265 @@ static int mangle_name(const char *name, char *target)
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return t - target;
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}
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/*
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* aafs - core fns and data for the policy tree
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*/
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#define AAFS_NAME "apparmorfs"
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static struct vfsmount *aafs_mnt;
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static int aafs_count;
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static int aafs_show_path(struct seq_file *seq, struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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seq_printf(seq, "%s:[%lu]", AAFS_NAME, inode->i_ino);
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return 0;
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}
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static void aafs_evict_inode(struct inode *inode)
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{
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truncate_inode_pages_final(&inode->i_data);
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clear_inode(inode);
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if (S_ISLNK(inode->i_mode))
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kfree(inode->i_link);
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}
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static const struct super_operations aafs_super_ops = {
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.statfs = simple_statfs,
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.evict_inode = aafs_evict_inode,
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.show_path = aafs_show_path,
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};
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static int fill_super(struct super_block *sb, void *data, int silent)
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{
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static struct tree_descr files[] = { {""} };
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int error;
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error = simple_fill_super(sb, AAFS_MAGIC, files);
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if (error)
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return error;
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sb->s_op = &aafs_super_ops;
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return 0;
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}
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static struct dentry *aafs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_single(fs_type, flags, data, fill_super);
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}
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static struct file_system_type aafs_ops = {
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.owner = THIS_MODULE,
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.name = AAFS_NAME,
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.mount = aafs_mount,
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.kill_sb = kill_anon_super,
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};
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/**
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* __aafs_setup_d_inode - basic inode setup for apparmorfs
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* @dir: parent directory for the dentry
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* @dentry: dentry we are seting the inode up for
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* @mode: permissions the file should have
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* @data: data to store on inode.i_private, available in open()
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* @link: if symlink, symlink target string
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* @fops: struct file_operations that should be used
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* @iops: struct of inode_operations that should be used
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*/
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static int __aafs_setup_d_inode(struct inode *dir, struct dentry *dentry,
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umode_t mode, void *data, char *link,
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const struct file_operations *fops,
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const struct inode_operations *iops)
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{
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struct inode *inode = new_inode(dir->i_sb);
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AA_BUG(!dir);
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AA_BUG(!dentry);
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if (!inode)
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return -ENOMEM;
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inode->i_ino = get_next_ino();
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inode->i_mode = mode;
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inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
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inode->i_private = data;
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if (S_ISDIR(mode)) {
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inode->i_op = iops ? iops : &simple_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(inode);
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inc_nlink(dir);
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} else if (S_ISLNK(mode)) {
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inode->i_op = iops ? iops : &simple_symlink_inode_operations;
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inode->i_link = link;
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} else {
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inode->i_fop = fops;
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}
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d_instantiate(dentry, inode);
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dget(dentry);
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return 0;
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}
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/**
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* aafs_create - create a dentry in the apparmorfs filesystem
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*
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* @name: name of dentry to create
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* @mode: permissions the file should have
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* @parent: parent directory for this dentry
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* @data: data to store on inode.i_private, available in open()
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* @link: if symlink, symlink target string
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* @fops: struct file_operations that should be used for
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* @iops: struct of inode_operations that should be used
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*
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* This is the basic "create a xxx" function for apparmorfs.
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*
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* Returns a pointer to a dentry if it succeeds, that must be free with
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* aafs_remove(). Will return ERR_PTR on failure.
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*/
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static struct dentry *aafs_create(const char *name, umode_t mode,
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struct dentry *parent, void *data, void *link,
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const struct file_operations *fops,
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const struct inode_operations *iops)
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{
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struct dentry *dentry;
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struct inode *dir;
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int error;
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AA_BUG(!name);
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AA_BUG(!parent);
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if (!(mode & S_IFMT))
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mode = (mode & S_IALLUGO) | S_IFREG;
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error = simple_pin_fs(&aafs_ops, &aafs_mnt, &aafs_count);
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if (error)
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return ERR_PTR(error);
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dir = d_inode(parent);
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inode_lock(dir);
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dentry = lookup_one_len(name, parent, strlen(name));
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if (IS_ERR(dentry))
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goto fail_lock;
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if (d_really_is_positive(dentry)) {
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error = -EEXIST;
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goto fail_dentry;
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}
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error = __aafs_setup_d_inode(dir, dentry, mode, data, link, fops, iops);
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if (error)
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goto fail_dentry;
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inode_unlock(dir);
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return dentry;
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fail_dentry:
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dput(dentry);
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fail_lock:
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inode_unlock(dir);
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simple_release_fs(&aafs_mnt, &aafs_count);
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return ERR_PTR(error);
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}
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/**
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* aafs_create_file - create a file in the apparmorfs filesystem
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*
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* @name: name of dentry to create
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* @mode: permissions the file should have
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* @parent: parent directory for this dentry
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* @data: data to store on inode.i_private, available in open()
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* @fops: struct file_operations that should be used for
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*
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* see aafs_create
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*/
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static struct dentry *aafs_create_file(const char *name, umode_t mode,
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struct dentry *parent, void *data,
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const struct file_operations *fops)
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{
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return aafs_create(name, mode, parent, data, NULL, fops, NULL);
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}
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/**
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* aafs_create_dir - create a directory in the apparmorfs filesystem
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*
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* @name: name of dentry to create
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* @parent: parent directory for this dentry
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*
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* see aafs_create
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*/
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static struct dentry *aafs_create_dir(const char *name, struct dentry *parent)
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{
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return aafs_create(name, S_IFDIR | 0755, parent, NULL, NULL, NULL,
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NULL);
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}
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/**
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* aafs_create_symlink - create a symlink in the apparmorfs filesystem
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* @name: name of dentry to create
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* @parent: parent directory for this dentry
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* @target: if symlink, symlink target string
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* @iops: struct of inode_operations that should be used
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*
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* If @target parameter is %NULL, then the @iops parameter needs to be
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* setup to handle .readlink and .get_link inode_operations.
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*/
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static struct dentry *aafs_create_symlink(const char *name,
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struct dentry *parent,
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const char *target,
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const struct inode_operations *iops)
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{
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struct dentry *dent;
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char *link = NULL;
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if (target) {
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link = kstrdup(target, GFP_KERNEL);
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if (!link)
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return ERR_PTR(-ENOMEM);
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}
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dent = aafs_create(name, S_IFLNK | 0444, parent, NULL, link, NULL,
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iops);
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if (IS_ERR(dent))
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kfree(link);
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return dent;
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}
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/**
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* aafs_remove - removes a file or directory from the apparmorfs filesystem
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*
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* @dentry: dentry of the file/directory/symlink to removed.
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*/
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static void aafs_remove(struct dentry *dentry)
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{
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struct inode *dir;
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if (!dentry || IS_ERR(dentry))
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return;
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dir = d_inode(dentry->d_parent);
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inode_lock(dir);
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if (simple_positive(dentry)) {
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if (d_is_dir(dentry))
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simple_rmdir(dir, dentry);
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else
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simple_unlink(dir, dentry);
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dput(dentry);
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}
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inode_unlock(dir);
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simple_release_fs(&aafs_mnt, &aafs_count);
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}
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/*
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* aa_fs - policy load/replace/remove
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*/
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/**
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* aa_simple_write_to_buffer - common routine for getting policy from user
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* @userbuf: user buffer to copy data from (NOT NULL)
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@ -1369,14 +1629,14 @@ static struct aa_fs_entry aa_fs_entry =
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AA_FS_DIR("apparmor", aa_fs_entry_apparmor);
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/**
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* aafs_create_file - create a file entry in the apparmor securityfs
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* entry_create_file - create a file entry in the apparmor securityfs
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* @fs_file: aa_fs_entry to build an entry for (NOT NULL)
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* @parent: the parent dentry in the securityfs
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*
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* Use aafs_remove_file to remove entries created with this fn.
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* Use entry_remove_file to remove entries created with this fn.
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*/
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static int __init aafs_create_file(struct aa_fs_entry *fs_file,
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struct dentry *parent)
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static int __init entry_create_file(struct aa_fs_entry *fs_file,
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struct dentry *parent)
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{
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int error = 0;
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@ -1391,15 +1651,15 @@ static int __init aafs_create_file(struct aa_fs_entry *fs_file,
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return error;
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}
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static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir);
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static void __init entry_remove_dir(struct aa_fs_entry *fs_dir);
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/**
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* aafs_create_dir - recursively create a directory entry in the securityfs
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* entry_create_dir - recursively create a directory entry in the securityfs
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* @fs_dir: aa_fs_entry (and all child entries) to build (NOT NULL)
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* @parent: the parent dentry in the securityfs
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*
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* Use aafs_remove_dir to remove entries created with this fn.
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* Use entry_remove_dir to remove entries created with this fn.
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*/
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static int __init aafs_create_dir(struct aa_fs_entry *fs_dir,
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static int __init entry_create_dir(struct aa_fs_entry *fs_dir,
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struct dentry *parent)
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{
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struct aa_fs_entry *fs_file;
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@ -1413,9 +1673,9 @@ static int __init aafs_create_dir(struct aa_fs_entry *fs_dir,
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for (fs_file = fs_dir->v.files; fs_file && fs_file->name; ++fs_file) {
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if (fs_file->v_type == AA_FS_TYPE_DIR)
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error = aafs_create_dir(fs_file, fs_dir->dentry);
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error = entry_create_dir(fs_file, fs_dir->dentry);
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else
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error = aafs_create_file(fs_file, fs_dir->dentry);
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error = entry_create_file(fs_file, fs_dir->dentry);
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if (error)
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goto failed;
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}
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@ -1423,7 +1683,7 @@ static int __init aafs_create_dir(struct aa_fs_entry *fs_dir,
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return 0;
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failed:
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aafs_remove_dir(fs_dir);
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entry_remove_dir(fs_dir);
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return error;
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}
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@ -1442,16 +1702,16 @@ static void __init aafs_remove_file(struct aa_fs_entry *fs_file)
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}
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/**
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* aafs_remove_dir - recursively drop a directory entry from the securityfs
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* entry_remove_dir - recursively drop a directory entry from the securityfs
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* @fs_dir: aa_fs_entry (and all child entries) to detach (NOT NULL)
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*/
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static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir)
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static void __init entry_remove_dir(struct aa_fs_entry *fs_dir)
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{
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struct aa_fs_entry *fs_file;
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for (fs_file = fs_dir->v.files; fs_file && fs_file->name; ++fs_file) {
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if (fs_file->v_type == AA_FS_TYPE_DIR)
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aafs_remove_dir(fs_file);
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entry_remove_dir(fs_file);
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else
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aafs_remove_file(fs_file);
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}
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@ -1466,7 +1726,7 @@ static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir)
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*/
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void __init aa_destroy_aafs(void)
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{
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aafs_remove_dir(&aa_fs_entry);
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entry_remove_dir(&aa_fs_entry);
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}
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@ -1515,6 +1775,59 @@ static int aa_mk_null_file(struct dentry *parent)
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return error;
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}
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static const char *policy_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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struct aa_ns *ns;
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struct path path;
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if (!dentry)
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return ERR_PTR(-ECHILD);
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ns = aa_get_current_ns();
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path.mnt = mntget(aafs_mnt);
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path.dentry = dget(ns_dir(ns));
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nd_jump_link(&path);
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aa_put_ns(ns);
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return NULL;
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}
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static int ns_get_name(char *buf, size_t size, struct aa_ns *ns,
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struct inode *inode)
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{
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int res = snprintf(buf, size, "%s:[%lu]", AAFS_NAME, inode->i_ino);
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if (res < 0 || res >= size)
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res = -ENOENT;
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return res;
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}
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static int policy_readlink(struct dentry *dentry, char __user *buffer,
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int buflen)
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{
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struct aa_ns *ns;
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char name[32];
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int res;
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ns = aa_get_current_ns();
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res = ns_get_name(name, sizeof(name), ns, d_inode(dentry));
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if (res >= 0)
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res = readlink_copy(buffer, buflen, name);
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aa_put_ns(ns);
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return res;
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}
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static const struct inode_operations policy_link_iops = {
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.readlink = policy_readlink,
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.get_link = policy_get_link,
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};
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/**
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* aa_create_aafs - create the apparmor security filesystem
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*
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@ -1535,8 +1848,14 @@ static int __init aa_create_aafs(void)
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return -EEXIST;
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}
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/* setup apparmorfs used to virtualize policy/ */
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aafs_mnt = kern_mount(&aafs_ops);
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if (IS_ERR(aafs_mnt))
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panic("can't set apparmorfs up\n");
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aafs_mnt->mnt_sb->s_flags &= ~MS_NOUSER;
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/* Populate fs tree. */
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error = aafs_create_dir(&aa_fs_entry, NULL);
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error = entry_create_dir(&aa_fs_entry, NULL);
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if (error)
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goto error;
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