Commit 2ea3ffb7 authored by John Johansen's avatar John Johansen
Browse files

apparmor: add mount mediation



Add basic mount mediation. That allows controlling based on basic
mount parameters. It does not include special mount parameters for
apparmor, super block labeling, or any triggers for apparmor namespace
parameter modifications on pivot root.

default userspace policy rules have the form of
  MOUNT RULE = ( MOUNT | REMOUNT | UMOUNT )

  MOUNT = [ QUALIFIERS ] 'mount' [ MOUNT CONDITIONS ] [ SOURCE FILEGLOB ]
          [ '->' MOUNTPOINT FILEGLOB ]

  REMOUNT = [ QUALIFIERS ] 'remount' [ MOUNT CONDITIONS ]
            MOUNTPOINT FILEGLOB

  UMOUNT = [ QUALIFIERS ] 'umount' [ MOUNT CONDITIONS ] MOUNTPOINT FILEGLOB

  MOUNT CONDITIONS = [ ( 'fstype' | 'vfstype' ) ( '=' | 'in' )
                       MOUNT FSTYPE EXPRESSION ]
		       [ 'options' ( '=' | 'in' ) MOUNT FLAGS EXPRESSION ]

  MOUNT FSTYPE EXPRESSION = ( MOUNT FSTYPE LIST | MOUNT EXPRESSION )

  MOUNT FSTYPE LIST = Comma separated list of valid filesystem and
                      virtual filesystem types (eg ext4, debugfs, etc)

  MOUNT FLAGS EXPRESSION = ( MOUNT FLAGS LIST | MOUNT EXPRESSION )

  MOUNT FLAGS LIST = Comma separated list of MOUNT FLAGS.

  MOUNT FLAGS = ( 'ro' | 'rw' | 'nosuid' | 'suid' | 'nodev' | 'dev' |
                  'noexec' | 'exec' | 'sync' | 'async' | 'remount' |
		  'mand' | 'nomand' | 'dirsync' | 'noatime' | 'atime' |
		  'nodiratime' | 'diratime' | 'bind' | 'rbind' | 'move' |
		  'verbose' | 'silent' | 'loud' | 'acl' | 'noacl' |
		  'unbindable' | 'runbindable' | 'private' | 'rprivate' |
		  'slave' | 'rslave' | 'shared' | 'rshared' |
		  'relatime' | 'norelatime' | 'iversion' | 'noiversion' |
		  'strictatime' | 'nouser' | 'user' )

  MOUNT EXPRESSION = ( ALPHANUMERIC | AARE ) ...

  PIVOT ROOT RULE = [ QUALIFIERS ] pivot_root [ oldroot=OLD PUT FILEGLOB ]
                    [ NEW ROOT FILEGLOB ]

  SOURCE FILEGLOB = FILEGLOB

  MOUNTPOINT FILEGLOB = FILEGLOB

eg.
  mount,
  mount /dev/foo,
  mount options=ro /dev/foo -> /mnt/,
  mount options in (ro,atime) /dev/foo -> /mnt/,
  mount options=ro options=atime,

Signed-off-by: default avatarJohn Johansen <john.johansen@canonical.com>
Acked-by: default avatarSeth Arnold <seth.arnold@canonical.com>
parent cd1dbf76
......@@ -4,7 +4,7 @@ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor.o
apparmor-y := apparmorfs.o audit.o capability.o context.o ipc.o lib.o match.o \
path.o domain.o policy.o policy_unpack.o procattr.o lsm.o \
resource.o secid.o file.o policy_ns.o label.o
resource.o secid.o file.o policy_ns.o label.o mount.o
apparmor-$(CONFIG_SECURITY_APPARMOR_HASH) += crypto.o
clean-files := capability_names.h rlim_names.h
......
......@@ -2159,9 +2159,14 @@ static struct aa_sfs_entry aa_sfs_entry_policy[] = {
{ }
};
static struct aa_sfs_entry aa_sfs_entry_mount[] = {
AA_SFS_FILE_STRING("mask", "mount umount pivot_root"),
{ }
};
static struct aa_sfs_entry aa_sfs_entry_ns[] = {
AA_SFS_FILE_BOOLEAN("profile", 1),
AA_SFS_FILE_BOOLEAN("pivot_root", 1),
AA_SFS_FILE_BOOLEAN("pivot_root", 0),
{ }
};
......@@ -2180,6 +2185,7 @@ static struct aa_sfs_entry aa_sfs_entry_features[] = {
AA_SFS_DIR("policy", aa_sfs_entry_policy),
AA_SFS_DIR("domain", aa_sfs_entry_domain),
AA_SFS_DIR("file", aa_sfs_entry_file),
AA_SFS_DIR("mount", aa_sfs_entry_mount),
AA_SFS_DIR("namespaces", aa_sfs_entry_ns),
AA_SFS_FILE_U64("capability", VFS_CAP_FLAGS_MASK),
AA_SFS_DIR("rlimit", aa_sfs_entry_rlimit),
......
......@@ -374,8 +374,8 @@ static const char *next_name(int xtype, const char *name)
*
* Returns: refcounted label, or NULL on failure (MAYBE NULL)
*/
static struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
const char **name)
struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
const char **name)
{
struct aa_label *label = NULL;
u32 xtype = xindex & AA_X_TYPE_MASK;
......
......@@ -27,6 +27,7 @@
#define AA_CLASS_NET 4
#define AA_CLASS_RLIMITS 5
#define AA_CLASS_DOMAIN 6
#define AA_CLASS_MOUNT 7
#define AA_CLASS_PTRACE 9
#define AA_CLASS_SIGNAL 10
#define AA_CLASS_LABEL 16
......
......@@ -71,6 +71,10 @@ enum audit_type {
#define OP_FMPROT "file_mprotect"
#define OP_INHERIT "file_inherit"
#define OP_PIVOTROOT "pivotroot"
#define OP_MOUNT "mount"
#define OP_UMOUNT "umount"
#define OP_CREATE "create"
#define OP_POST_CREATE "post_create"
#define OP_BIND "bind"
......@@ -132,6 +136,13 @@ struct apparmor_audit_data {
int rlim;
unsigned long max;
} rlim;
struct {
const char *src_name;
const char *type;
const char *trans;
const char *data;
unsigned long flags;
} mnt;
};
};
......
......@@ -15,6 +15,8 @@
#include <linux/binfmts.h>
#include <linux/types.h>
#include "label.h"
#ifndef __AA_DOMAIN_H
#define __AA_DOMAIN_H
......@@ -29,6 +31,9 @@ struct aa_domain {
#define AA_CHANGE_ONEXEC 4
#define AA_CHANGE_STACK 8
struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
const char **name);
int apparmor_bprm_set_creds(struct linux_binprm *bprm);
int apparmor_bprm_secureexec(struct linux_binprm *bprm);
......
/*
* AppArmor security module
*
* This file contains AppArmor file mediation function definitions.
*
* Copyright 2017 Canonical Ltd.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*/
#ifndef __AA_MOUNT_H
#define __AA_MOUNT_H
#include <linux/fs.h>
#include <linux/path.h>
#include "domain.h"
#include "policy.h"
/* mount perms */
#define AA_MAY_PIVOTROOT 0x01
#define AA_MAY_MOUNT 0x02
#define AA_MAY_UMOUNT 0x04
#define AA_AUDIT_DATA 0x40
#define AA_MNT_CONT_MATCH 0x40
#define AA_MS_IGNORE_MASK (MS_KERNMOUNT | MS_NOSEC | MS_ACTIVE | MS_BORN)
int aa_remount(struct aa_label *label, const struct path *path,
unsigned long flags, void *data);
int aa_bind_mount(struct aa_label *label, const struct path *path,
const char *old_name, unsigned long flags);
int aa_mount_change_type(struct aa_label *label, const struct path *path,
unsigned long flags);
int aa_move_mount(struct aa_label *label, const struct path *path,
const char *old_name);
int aa_new_mount(struct aa_label *label, const char *dev_name,
const struct path *path, const char *type, unsigned long flags,
void *data);
int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags);
int aa_pivotroot(struct aa_label *label, const struct path *old_path,
const struct path *new_path);
#endif /* __AA_MOUNT_H */
......@@ -38,6 +38,7 @@
#include "include/policy.h"
#include "include/policy_ns.h"
#include "include/procattr.h"
#include "include/mount.h"
/* Flag indicating whether initialization completed */
int apparmor_initialized;
......@@ -511,6 +512,65 @@ static int apparmor_file_mprotect(struct vm_area_struct *vma,
!(vma->vm_flags & VM_SHARED) ? MAP_PRIVATE : 0);
}
static int apparmor_sb_mount(const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data)
{
struct aa_label *label;
int error = 0;
/* Discard magic */
if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
flags &= ~MS_MGC_MSK;
flags &= ~AA_MS_IGNORE_MASK;
label = __begin_current_label_crit_section();
if (!unconfined(label)) {
if (flags & MS_REMOUNT)
error = aa_remount(label, path, flags, data);
else if (flags & MS_BIND)
error = aa_bind_mount(label, path, dev_name, flags);
else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE |
MS_UNBINDABLE))
error = aa_mount_change_type(label, path, flags);
else if (flags & MS_MOVE)
error = aa_move_mount(label, path, dev_name);
else
error = aa_new_mount(label, dev_name, path, type,
flags, data);
}
__end_current_label_crit_section(label);
return error;
}
static int apparmor_sb_umount(struct vfsmount *mnt, int flags)
{
struct aa_label *label;
int error = 0;
label = __begin_current_label_crit_section();
if (!unconfined(label))
error = aa_umount(label, mnt, flags);
__end_current_label_crit_section(label);
return error;
}
static int apparmor_sb_pivotroot(const struct path *old_path,
const struct path *new_path)
{
struct aa_label *label;
int error = 0;
label = aa_get_current_label();
if (!unconfined(label))
error = aa_pivotroot(label, old_path, new_path);
aa_put_label(label);
return error;
}
static int apparmor_getprocattr(struct task_struct *task, char *name,
char **value)
{
......@@ -682,6 +742,10 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(capget, apparmor_capget),
LSM_HOOK_INIT(capable, apparmor_capable),
LSM_HOOK_INIT(sb_mount, apparmor_sb_mount),
LSM_HOOK_INIT(sb_umount, apparmor_sb_umount),
LSM_HOOK_INIT(sb_pivotroot, apparmor_sb_pivotroot),
LSM_HOOK_INIT(path_link, apparmor_path_link),
LSM_HOOK_INIT(path_unlink, apparmor_path_unlink),
LSM_HOOK_INIT(path_symlink, apparmor_path_symlink),
......
/*
* AppArmor security module
*
* This file contains AppArmor mediation of files
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2017 Canonical Ltd.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*/
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include "include/apparmor.h"
#include "include/audit.h"
#include "include/context.h"
#include "include/domain.h"
#include "include/file.h"
#include "include/match.h"
#include "include/mount.h"
#include "include/path.h"
#include "include/policy.h"
static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags)
{
if (flags & MS_RDONLY)
audit_log_format(ab, "ro");
else
audit_log_format(ab, "rw");
if (flags & MS_NOSUID)
audit_log_format(ab, ", nosuid");
if (flags & MS_NODEV)
audit_log_format(ab, ", nodev");
if (flags & MS_NOEXEC)
audit_log_format(ab, ", noexec");
if (flags & MS_SYNCHRONOUS)
audit_log_format(ab, ", sync");
if (flags & MS_REMOUNT)
audit_log_format(ab, ", remount");
if (flags & MS_MANDLOCK)
audit_log_format(ab, ", mand");
if (flags & MS_DIRSYNC)
audit_log_format(ab, ", dirsync");
if (flags & MS_NOATIME)
audit_log_format(ab, ", noatime");
if (flags & MS_NODIRATIME)
audit_log_format(ab, ", nodiratime");
if (flags & MS_BIND)
audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind");
if (flags & MS_MOVE)
audit_log_format(ab, ", move");
if (flags & MS_SILENT)
audit_log_format(ab, ", silent");
if (flags & MS_POSIXACL)
audit_log_format(ab, ", acl");
if (flags & MS_UNBINDABLE)
audit_log_format(ab, flags & MS_REC ? ", runbindable" :
", unbindable");
if (flags & MS_PRIVATE)
audit_log_format(ab, flags & MS_REC ? ", rprivate" :
", private");
if (flags & MS_SLAVE)
audit_log_format(ab, flags & MS_REC ? ", rslave" :
", slave");
if (flags & MS_SHARED)
audit_log_format(ab, flags & MS_REC ? ", rshared" :
", shared");
if (flags & MS_RELATIME)
audit_log_format(ab, ", relatime");
if (flags & MS_I_VERSION)
audit_log_format(ab, ", iversion");
if (flags & MS_STRICTATIME)
audit_log_format(ab, ", strictatime");
if (flags & MS_NOUSER)
audit_log_format(ab, ", nouser");
}
/**
* audit_cb - call back for mount specific audit fields
* @ab: audit_buffer (NOT NULL)
* @va: audit struct to audit values of (NOT NULL)
*/
static void audit_cb(struct audit_buffer *ab, void *va)
{
struct common_audit_data *sa = va;
if (aad(sa)->mnt.type) {
audit_log_format(ab, " fstype=");
audit_log_untrustedstring(ab, aad(sa)->mnt.type);
}
if (aad(sa)->mnt.src_name) {
audit_log_format(ab, " srcname=");
audit_log_untrustedstring(ab, aad(sa)->mnt.src_name);
}
if (aad(sa)->mnt.trans) {
audit_log_format(ab, " trans=");
audit_log_untrustedstring(ab, aad(sa)->mnt.trans);
}
if (aad(sa)->mnt.flags) {
audit_log_format(ab, " flags=\"");
audit_mnt_flags(ab, aad(sa)->mnt.flags);
audit_log_format(ab, "\"");
}
if (aad(sa)->mnt.data) {
audit_log_format(ab, " options=");
audit_log_untrustedstring(ab, aad(sa)->mnt.data);
}
}
/**
* audit_mount - handle the auditing of mount operations
* @profile: the profile being enforced (NOT NULL)
* @op: operation being mediated (NOT NULL)
* @name: name of object being mediated (MAYBE NULL)
* @src_name: src_name of object being mediated (MAYBE_NULL)
* @type: type of filesystem (MAYBE_NULL)
* @trans: name of trans (MAYBE NULL)
* @flags: filesystem idependent mount flags
* @data: filesystem mount flags
* @request: permissions requested
* @perms: the permissions computed for the request (NOT NULL)
* @info: extra information message (MAYBE NULL)
* @error: 0 if operation allowed else failure error code
*
* Returns: %0 or error on failure
*/
static int audit_mount(struct aa_profile *profile, const char *op,
const char *name, const char *src_name,
const char *type, const char *trans,
unsigned long flags, const void *data, u32 request,
struct aa_perms *perms, const char *info, int error)
{
int audit_type = AUDIT_APPARMOR_AUTO;
DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, op);
if (likely(!error)) {
u32 mask = perms->audit;
if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
mask = 0xffff;
/* mask off perms that are not being force audited */
request &= mask;
if (likely(!request))
return 0;
audit_type = AUDIT_APPARMOR_AUDIT;
} else {
/* only report permissions that were denied */
request = request & ~perms->allow;
if (request & perms->kill)
audit_type = AUDIT_APPARMOR_KILL;
/* quiet known rejects, assumes quiet and kill do not overlap */
if ((request & perms->quiet) &&
AUDIT_MODE(profile) != AUDIT_NOQUIET &&
AUDIT_MODE(profile) != AUDIT_ALL)
request &= ~perms->quiet;
if (!request)
return error;
}
aad(&sa)->name = name;
aad(&sa)->mnt.src_name = src_name;
aad(&sa)->mnt.type = type;
aad(&sa)->mnt.trans = trans;
aad(&sa)->mnt.flags = flags;
if (data && (perms->audit & AA_AUDIT_DATA))
aad(&sa)->mnt.data = data;
aad(&sa)->info = info;
aad(&sa)->error = error;
return aa_audit(audit_type, profile, &sa, audit_cb);
}
/**
* match_mnt_flags - Do an ordered match on mount flags
* @dfa: dfa to match against
* @state: state to start in
* @flags: mount flags to match against
*
* Mount flags are encoded as an ordered match. This is done instead of
* checking against a simple bitmask, to allow for logical operations
* on the flags.
*
* Returns: next state after flags match
*/
static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state,
unsigned long flags)
{
unsigned int i;
for (i = 0; i <= 31 ; ++i) {
if ((1 << i) & flags)
state = aa_dfa_next(dfa, state, i + 1);
}
return state;
}
/**
* compute_mnt_perms - compute mount permission associated with @state
* @dfa: dfa to match against (NOT NULL)
* @state: state match finished in
*
* Returns: mount permissions
*/
static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa,
unsigned int state)
{
struct aa_perms perms;
perms.kill = 0;
perms.allow = dfa_user_allow(dfa, state);
perms.audit = dfa_user_audit(dfa, state);
perms.quiet = dfa_user_quiet(dfa, state);
perms.xindex = dfa_user_xindex(dfa, state);
return perms;
}
static const char * const mnt_info_table[] = {
"match succeeded",
"failed mntpnt match",
"failed srcname match",
"failed type match",
"failed flags match",
"failed data match"
};
/*
* Returns 0 on success else element that match failed in, this is the
* index into the mnt_info_table above
*/
static int do_match_mnt(struct aa_dfa *dfa, unsigned int start,
const char *mntpnt, const char *devname,
const char *type, unsigned long flags,
void *data, bool binary, struct aa_perms *perms)
{
unsigned int state;
AA_BUG(!dfa);
AA_BUG(!perms);
state = aa_dfa_match(dfa, start, mntpnt);
state = aa_dfa_null_transition(dfa, state);
if (!state)
return 1;
if (devname)
state = aa_dfa_match(dfa, state, devname);
state = aa_dfa_null_transition(dfa, state);
if (!state)
return 2;
if (type)
state = aa_dfa_match(dfa, state, type);
state = aa_dfa_null_transition(dfa, state);
if (!state)
return 3;
state = match_mnt_flags(dfa, state, flags);
if (!state)
return 4;
*perms = compute_mnt_perms(dfa, state);
if (perms->allow & AA_MAY_MOUNT)
return 0;
/* only match data if not binary and the DFA flags data is expected */
if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) {
state = aa_dfa_null_transition(dfa, state);
if (!state)
return 4;
state = aa_dfa_match(dfa, state, data);
if (!state)
return 5;
*perms = compute_mnt_perms(dfa, state);
if (perms->allow & AA_MAY_MOUNT)
return 0;
}
/* failed at end of flags match */
return 4;
}
static int path_flags(struct aa_profile *profile, const struct path *path)
{
AA_BUG(!profile);
AA_BUG(!path);
return profile->path_flags |
(S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0);
}
/**
* match_mnt_path_str - handle path matching for mount
* @profile: the confining profile
* @mntpath: for the mntpnt (NOT NULL)
* @buffer: buffer to be used to lookup mntpath
* @devnme: string for the devname/src_name (MAY BE NULL OR ERRPTR)
* @type: string for the dev type (MAYBE NULL)
* @flags: mount flags to match
* @data: fs mount data (MAYBE NULL)
* @binary: whether @data is binary
* @devinfo: error str if (IS_ERR(@devname))
*
* Returns: 0 on success else error
*/
static int match_mnt_path_str(struct aa_profile *profile,
const struct path *mntpath, char *buffer,
const char *devname, const char *type,
unsigned long flags, void *data, bool binary,
const char *devinfo)
{
struct aa_perms perms = { };
const char *mntpnt = NULL, *info = NULL;
int pos, error;
AA_BUG(!profile);
AA_BUG(!mntpath);
AA_BUG(!buffer);
error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer,
&mntpnt, &info, profile->disconnected);
if (error)
goto audit;
if (IS_ERR(devname)) {
error = PTR_ERR(devname);
devname = NULL;
info = devinfo;
goto audit;
}
error = -EACCES;
pos = do_match_mnt(profile->policy.dfa,
profile->policy.start[AA_CLASS_MOUNT],
mntpnt, devname, type, flags, data, binary, &perms);
if (pos) {
info = mnt_info_table[pos];
goto audit;
}
error = 0;
audit:
return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL,
flags, data, AA_MAY_MOUNT, &perms, info, error);
}
/**
* match_mnt - handle path matching for mount
* @profile: the confining profile
* @mntpath: for the mntpnt (NOT NULL)
* @buffer: buffer to be used to lookup mntpath
* @devpath: path devname/src_name (MAYBE NULL)
* @devbuffer: buffer to be used to lookup devname/src_name
* @type: string for the dev type (MAYBE NULL)
* @flags: mount flags to match
* @data: fs mount data (MAYBE NULL)
* @binary: whether @data is binary
*
* Returns: 0 on success else error
*/
static int match_mnt(struct aa_profile *profile, const struct path *path,
char *buffer, struct path *devpath, char *devbuffer,
const char *type, unsigned