From a481f4d917835cad86701fc0d1e620c74bb5cd5f Mon Sep 17 00:00:00 2001 From: John Johansen Date: Thu, 25 May 2017 05:52:56 -0700 Subject: [PATCH] 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 Reviewed-by: Seth Arnold Reviewed-by: Kees Cook --- include/uapi/linux/magic.h | 2 + security/apparmor/apparmorfs.c | 353 +++++++++++++++++++++++++++++++-- 2 files changed, 338 insertions(+), 17 deletions(-) diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index e230af2e6855..a0908f1d2760 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -80,6 +80,8 @@ #define BTRFS_TEST_MAGIC 0x73727279 #define NSFS_MAGIC 0x6e736673 #define BPF_FS_MAGIC 0xcafe4a11 +#define AAFS_MAGIC 0x5a3c69f0 + /* Since UDF 2.01 is ISO 13346 based... */ #define UDF_SUPER_MAGIC 0x15013346 #define BALLOON_KVM_MAGIC 0x13661366 diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c index 16680d15d43e..7e4b7f28ee20 100644 --- a/security/apparmor/apparmorfs.c +++ b/security/apparmor/apparmorfs.c @@ -22,8 +22,9 @@ #include #include #include -#include #include +#include +#include #include "include/apparmor.h" #include "include/apparmorfs.h" @@ -74,6 +75,265 @@ static int mangle_name(const char *name, char *target) return t - target; } + +/* + * aafs - core fns and data for the policy tree + */ + +#define AAFS_NAME "apparmorfs" +static struct vfsmount *aafs_mnt; +static int aafs_count; + + +static int aafs_show_path(struct seq_file *seq, struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + + seq_printf(seq, "%s:[%lu]", AAFS_NAME, inode->i_ino); + return 0; +} + +static void aafs_evict_inode(struct inode *inode) +{ + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + if (S_ISLNK(inode->i_mode)) + kfree(inode->i_link); +} + +static const struct super_operations aafs_super_ops = { + .statfs = simple_statfs, + .evict_inode = aafs_evict_inode, + .show_path = aafs_show_path, +}; + +static int fill_super(struct super_block *sb, void *data, int silent) +{ + static struct tree_descr files[] = { {""} }; + int error; + + error = simple_fill_super(sb, AAFS_MAGIC, files); + if (error) + return error; + sb->s_op = &aafs_super_ops; + + return 0; +} + +static struct dentry *aafs_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_single(fs_type, flags, data, fill_super); +} + +static struct file_system_type aafs_ops = { + .owner = THIS_MODULE, + .name = AAFS_NAME, + .mount = aafs_mount, + .kill_sb = kill_anon_super, +}; + +/** + * __aafs_setup_d_inode - basic inode setup for apparmorfs + * @dir: parent directory for the dentry + * @dentry: dentry we are seting the inode up for + * @mode: permissions the file should have + * @data: data to store on inode.i_private, available in open() + * @link: if symlink, symlink target string + * @fops: struct file_operations that should be used + * @iops: struct of inode_operations that should be used + */ +static int __aafs_setup_d_inode(struct inode *dir, struct dentry *dentry, + umode_t mode, void *data, char *link, + const struct file_operations *fops, + const struct inode_operations *iops) +{ + struct inode *inode = new_inode(dir->i_sb); + + AA_BUG(!dir); + AA_BUG(!dentry); + + if (!inode) + return -ENOMEM; + + inode->i_ino = get_next_ino(); + inode->i_mode = mode; + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + inode->i_private = data; + if (S_ISDIR(mode)) { + inode->i_op = iops ? iops : &simple_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + inc_nlink(inode); + inc_nlink(dir); + } else if (S_ISLNK(mode)) { + inode->i_op = iops ? iops : &simple_symlink_inode_operations; + inode->i_link = link; + } else { + inode->i_fop = fops; + } + d_instantiate(dentry, inode); + dget(dentry); + + return 0; +} + +/** + * aafs_create - create a dentry in the apparmorfs filesystem + * + * @name: name of dentry to create + * @mode: permissions the file should have + * @parent: parent directory for this dentry + * @data: data to store on inode.i_private, available in open() + * @link: if symlink, symlink target string + * @fops: struct file_operations that should be used for + * @iops: struct of inode_operations that should be used + * + * This is the basic "create a xxx" function for apparmorfs. + * + * Returns a pointer to a dentry if it succeeds, that must be free with + * aafs_remove(). Will return ERR_PTR on failure. + */ +static struct dentry *aafs_create(const char *name, umode_t mode, + struct dentry *parent, void *data, void *link, + const struct file_operations *fops, + const struct inode_operations *iops) +{ + struct dentry *dentry; + struct inode *dir; + int error; + + AA_BUG(!name); + AA_BUG(!parent); + + if (!(mode & S_IFMT)) + mode = (mode & S_IALLUGO) | S_IFREG; + + error = simple_pin_fs(&aafs_ops, &aafs_mnt, &aafs_count); + if (error) + return ERR_PTR(error); + + dir = d_inode(parent); + + inode_lock(dir); + dentry = lookup_one_len(name, parent, strlen(name)); + if (IS_ERR(dentry)) + goto fail_lock; + + if (d_really_is_positive(dentry)) { + error = -EEXIST; + goto fail_dentry; + } + + error = __aafs_setup_d_inode(dir, dentry, mode, data, link, fops, iops); + if (error) + goto fail_dentry; + inode_unlock(dir); + + return dentry; + +fail_dentry: + dput(dentry); + +fail_lock: + inode_unlock(dir); + simple_release_fs(&aafs_mnt, &aafs_count); + + return ERR_PTR(error); +} + +/** + * aafs_create_file - create a file in the apparmorfs filesystem + * + * @name: name of dentry to create + * @mode: permissions the file should have + * @parent: parent directory for this dentry + * @data: data to store on inode.i_private, available in open() + * @fops: struct file_operations that should be used for + * + * see aafs_create + */ +static struct dentry *aafs_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops) +{ + return aafs_create(name, mode, parent, data, NULL, fops, NULL); +} + +/** + * aafs_create_dir - create a directory in the apparmorfs filesystem + * + * @name: name of dentry to create + * @parent: parent directory for this dentry + * + * see aafs_create + */ +static struct dentry *aafs_create_dir(const char *name, struct dentry *parent) +{ + return aafs_create(name, S_IFDIR | 0755, parent, NULL, NULL, NULL, + NULL); +} + +/** + * aafs_create_symlink - create a symlink in the apparmorfs filesystem + * @name: name of dentry to create + * @parent: parent directory for this dentry + * @target: if symlink, symlink target string + * @iops: struct of inode_operations that should be used + * + * If @target parameter is %NULL, then the @iops parameter needs to be + * setup to handle .readlink and .get_link inode_operations. + */ +static struct dentry *aafs_create_symlink(const char *name, + struct dentry *parent, + const char *target, + const struct inode_operations *iops) +{ + struct dentry *dent; + char *link = NULL; + + if (target) { + link = kstrdup(target, GFP_KERNEL); + if (!link) + return ERR_PTR(-ENOMEM); + } + dent = aafs_create(name, S_IFLNK | 0444, parent, NULL, link, NULL, + iops); + if (IS_ERR(dent)) + kfree(link); + + return dent; +} + +/** + * aafs_remove - removes a file or directory from the apparmorfs filesystem + * + * @dentry: dentry of the file/directory/symlink to removed. + */ +static void aafs_remove(struct dentry *dentry) +{ + struct inode *dir; + + if (!dentry || IS_ERR(dentry)) + return; + + dir = d_inode(dentry->d_parent); + inode_lock(dir); + if (simple_positive(dentry)) { + if (d_is_dir(dentry)) + simple_rmdir(dir, dentry); + else + simple_unlink(dir, dentry); + dput(dentry); + } + inode_unlock(dir); + simple_release_fs(&aafs_mnt, &aafs_count); +} + + +/* + * aa_fs - policy load/replace/remove + */ + /** * aa_simple_write_to_buffer - common routine for getting policy from user * @userbuf: user buffer to copy data from (NOT NULL) @@ -1369,14 +1629,14 @@ static struct aa_fs_entry aa_fs_entry = AA_FS_DIR("apparmor", aa_fs_entry_apparmor); /** - * aafs_create_file - create a file entry in the apparmor securityfs + * entry_create_file - create a file entry in the apparmor securityfs * @fs_file: aa_fs_entry to build an entry for (NOT NULL) * @parent: the parent dentry in the securityfs * - * Use aafs_remove_file to remove entries created with this fn. + * Use entry_remove_file to remove entries created with this fn. */ -static int __init aafs_create_file(struct aa_fs_entry *fs_file, - struct dentry *parent) +static int __init entry_create_file(struct aa_fs_entry *fs_file, + struct dentry *parent) { int error = 0; @@ -1391,15 +1651,15 @@ static int __init aafs_create_file(struct aa_fs_entry *fs_file, return error; } -static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir); +static void __init entry_remove_dir(struct aa_fs_entry *fs_dir); /** - * aafs_create_dir - recursively create a directory entry in the securityfs + * entry_create_dir - recursively create a directory entry in the securityfs * @fs_dir: aa_fs_entry (and all child entries) to build (NOT NULL) * @parent: the parent dentry in the securityfs * - * Use aafs_remove_dir to remove entries created with this fn. + * Use entry_remove_dir to remove entries created with this fn. */ -static int __init aafs_create_dir(struct aa_fs_entry *fs_dir, +static int __init entry_create_dir(struct aa_fs_entry *fs_dir, struct dentry *parent) { struct aa_fs_entry *fs_file; @@ -1413,9 +1673,9 @@ static int __init aafs_create_dir(struct aa_fs_entry *fs_dir, for (fs_file = fs_dir->v.files; fs_file && fs_file->name; ++fs_file) { if (fs_file->v_type == AA_FS_TYPE_DIR) - error = aafs_create_dir(fs_file, fs_dir->dentry); + error = entry_create_dir(fs_file, fs_dir->dentry); else - error = aafs_create_file(fs_file, fs_dir->dentry); + error = entry_create_file(fs_file, fs_dir->dentry); if (error) goto failed; } @@ -1423,7 +1683,7 @@ static int __init aafs_create_dir(struct aa_fs_entry *fs_dir, return 0; failed: - aafs_remove_dir(fs_dir); + entry_remove_dir(fs_dir); return error; } @@ -1442,16 +1702,16 @@ static void __init aafs_remove_file(struct aa_fs_entry *fs_file) } /** - * aafs_remove_dir - recursively drop a directory entry from the securityfs + * entry_remove_dir - recursively drop a directory entry from the securityfs * @fs_dir: aa_fs_entry (and all child entries) to detach (NOT NULL) */ -static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir) +static void __init entry_remove_dir(struct aa_fs_entry *fs_dir) { struct aa_fs_entry *fs_file; for (fs_file = fs_dir->v.files; fs_file && fs_file->name; ++fs_file) { if (fs_file->v_type == AA_FS_TYPE_DIR) - aafs_remove_dir(fs_file); + entry_remove_dir(fs_file); else aafs_remove_file(fs_file); } @@ -1466,7 +1726,7 @@ static void __init aafs_remove_dir(struct aa_fs_entry *fs_dir) */ void __init aa_destroy_aafs(void) { - aafs_remove_dir(&aa_fs_entry); + entry_remove_dir(&aa_fs_entry); } @@ -1515,6 +1775,59 @@ out: return error; } + + +static const char *policy_get_link(struct dentry *dentry, + struct inode *inode, + struct delayed_call *done) +{ + struct aa_ns *ns; + struct path path; + + if (!dentry) + return ERR_PTR(-ECHILD); + ns = aa_get_current_ns(); + path.mnt = mntget(aafs_mnt); + path.dentry = dget(ns_dir(ns)); + nd_jump_link(&path); + aa_put_ns(ns); + + return NULL; +} + +static int ns_get_name(char *buf, size_t size, struct aa_ns *ns, + struct inode *inode) +{ + int res = snprintf(buf, size, "%s:[%lu]", AAFS_NAME, inode->i_ino); + + if (res < 0 || res >= size) + res = -ENOENT; + + return res; +} + +static int policy_readlink(struct dentry *dentry, char __user *buffer, + int buflen) +{ + struct aa_ns *ns; + char name[32]; + int res; + + ns = aa_get_current_ns(); + res = ns_get_name(name, sizeof(name), ns, d_inode(dentry)); + if (res >= 0) + res = readlink_copy(buffer, buflen, name); + aa_put_ns(ns); + + return res; +} + +static const struct inode_operations policy_link_iops = { + .readlink = policy_readlink, + .get_link = policy_get_link, +}; + + /** * aa_create_aafs - create the apparmor security filesystem * @@ -1535,8 +1848,14 @@ static int __init aa_create_aafs(void) return -EEXIST; } + /* setup apparmorfs used to virtualize policy/ */ + aafs_mnt = kern_mount(&aafs_ops); + if (IS_ERR(aafs_mnt)) + panic("can't set apparmorfs up\n"); + aafs_mnt->mnt_sb->s_flags &= ~MS_NOUSER; + /* Populate fs tree. */ - error = aafs_create_dir(&aa_fs_entry, NULL); + error = entry_create_dir(&aa_fs_entry, NULL); if (error) goto error; -- 2.20.1