blob: 5cc5de062fc85e79020b8bdc814687dcb2309b6b [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
/*
* AppArmor security module
*
* This file contains AppArmor mediation of files
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2017 Canonical Ltd.
*/
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <uapi/linux/mount.h>
#include "include/apparmor.h"
#include "include/audit.h"
#include "include/cred.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 independent 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 = {
.allow = dfa_user_allow(dfa, state),
.audit = dfa_user_audit(dfa, state),
.quiet = dfa_user_quiet(dfa, state),
.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",
"failed perms check"
};
/*
* 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 perms check, don't confuse with flags match */
return 6;
}
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
* @devname: 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);
if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
return 0;
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
* @path: 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, const struct path *devpath, char *devbuffer,
const char *type, unsigned long flags, void *data,
bool binary)
{
const char *devname = NULL, *info = NULL;
int error = -EACCES;
AA_BUG(!profile);
AA_BUG(devpath && !devbuffer);
if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
return 0;
if (devpath) {
error = aa_path_name(devpath, path_flags(profile, devpath),
devbuffer, &devname, &info,
profile->disconnected);
if (error)
devname = ERR_PTR(error);
}
return match_mnt_path_str(profile, path, buffer, devname, type, flags,
data, binary, info);
}
int aa_remount(struct aa_label *label, const struct path *path,
unsigned long flags, void *data)
{
struct aa_profile *profile;
char *buffer = NULL;
bool binary;
int error;
AA_BUG(!label);
AA_BUG(!path);
binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA;
buffer = aa_get_buffer(false);
if (!buffer)
return -ENOMEM;
error = fn_for_each_confined(label, profile,
match_mnt(profile, path, buffer, NULL, NULL, NULL,
flags, data, binary));
aa_put_buffer(buffer);
return error;
}
int aa_bind_mount(struct aa_label *label, const struct path *path,
const char *dev_name, unsigned long flags)
{
struct aa_profile *profile;
char *buffer = NULL, *old_buffer = NULL;
struct path old_path;
int error;
AA_BUG(!label);
AA_BUG(!path);
if (!dev_name || !*dev_name)
return -EINVAL;
flags &= MS_REC | MS_BIND;
error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
if (error)
return error;
buffer = aa_get_buffer(false);
old_buffer = aa_get_buffer(false);
error = -ENOMEM;
if (!buffer || !old_buffer)
goto out;
error = fn_for_each_confined(label, profile,
match_mnt(profile, path, buffer, &old_path, old_buffer,
NULL, flags, NULL, false));
out:
aa_put_buffer(buffer);
aa_put_buffer(old_buffer);
path_put(&old_path);
return error;
}
int aa_mount_change_type(struct aa_label *label, const struct path *path,
unsigned long flags)
{
struct aa_profile *profile;
char *buffer = NULL;
int error;
AA_BUG(!label);
AA_BUG(!path);
/* These are the flags allowed by do_change_type() */
flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE |
MS_UNBINDABLE);
buffer = aa_get_buffer(false);
if (!buffer)
return -ENOMEM;
error = fn_for_each_confined(label, profile,
match_mnt(profile, path, buffer, NULL, NULL, NULL,
flags, NULL, false));
aa_put_buffer(buffer);
return error;
}
int aa_move_mount(struct aa_label *label, const struct path *path,
const char *orig_name)
{
struct aa_profile *profile;
char *buffer = NULL, *old_buffer = NULL;
struct path old_path;
int error;
AA_BUG(!label);
AA_BUG(!path);
if (!orig_name || !*orig_name)
return -EINVAL;
error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path);
if (error)
return error;
buffer = aa_get_buffer(false);
old_buffer = aa_get_buffer(false);
error = -ENOMEM;
if (!buffer || !old_buffer)
goto out;
error = fn_for_each_confined(label, profile,
match_mnt(profile, path, buffer, &old_path, old_buffer,
NULL, MS_MOVE, NULL, false));
out:
aa_put_buffer(buffer);
aa_put_buffer(old_buffer);
path_put(&old_path);
return error;
}
int aa_new_mount(struct aa_label *label, const char *dev_name,
const struct path *path, const char *type, unsigned long flags,
void *data)
{
struct aa_profile *profile;
char *buffer = NULL, *dev_buffer = NULL;
bool binary = true;
int error;
int requires_dev = 0;
struct path tmp_path, *dev_path = NULL;
AA_BUG(!label);
AA_BUG(!path);
if (type) {
struct file_system_type *fstype;
fstype = get_fs_type(type);
if (!fstype)
return -ENODEV;
binary = fstype->fs_flags & FS_BINARY_MOUNTDATA;
requires_dev = fstype->fs_flags & FS_REQUIRES_DEV;
put_filesystem(fstype);
if (requires_dev) {
if (!dev_name || !*dev_name)
return -ENOENT;
error = kern_path(dev_name, LOOKUP_FOLLOW, &tmp_path);
if (error)
return error;
dev_path = &tmp_path;
}
}
buffer = aa_get_buffer(false);
if (!buffer) {
error = -ENOMEM;
goto out;
}
if (dev_path) {
dev_buffer = aa_get_buffer(false);
if (!dev_buffer) {
error = -ENOMEM;
goto out;
}
error = fn_for_each_confined(label, profile,
match_mnt(profile, path, buffer, dev_path, dev_buffer,
type, flags, data, binary));
} else {
error = fn_for_each_confined(label, profile,
match_mnt_path_str(profile, path, buffer, dev_name,
type, flags, data, binary, NULL));
}
out:
aa_put_buffer(buffer);
aa_put_buffer(dev_buffer);
if (dev_path)
path_put(dev_path);
return error;
}
static int profile_umount(struct aa_profile *profile, const struct path *path,
char *buffer)
{
struct aa_perms perms = { };
const char *name = NULL, *info = NULL;
unsigned int state;
int error;
AA_BUG(!profile);
AA_BUG(!path);
if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
return 0;
error = aa_path_name(path, path_flags(profile, path), buffer, &name,
&info, profile->disconnected);
if (error)
goto audit;
state = aa_dfa_match(profile->policy.dfa,
profile->policy.start[AA_CLASS_MOUNT],
name);
perms = compute_mnt_perms(profile->policy.dfa, state);
if (AA_MAY_UMOUNT & ~perms.allow)
error = -EACCES;
audit:
return audit_mount(profile, OP_UMOUNT, name, NULL, NULL, NULL, 0, NULL,
AA_MAY_UMOUNT, &perms, info, error);
}
int aa_umount(struct aa_label *label, struct vfsmount *mnt, int flags)
{
struct aa_profile *profile;
char *buffer = NULL;
int error;
struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
AA_BUG(!label);
AA_BUG(!mnt);
buffer = aa_get_buffer(false);
if (!buffer)
return -ENOMEM;
error = fn_for_each_confined(label, profile,
profile_umount(profile, &path, buffer));
aa_put_buffer(buffer);
return error;
}
/* helper fn for transition on pivotroot
*
* Returns: label for transition or ERR_PTR. Does not return NULL
*/
static struct aa_label *build_pivotroot(struct aa_profile *profile,
const struct path *new_path,
char *new_buffer,
const struct path *old_path,
char *old_buffer)
{
const char *old_name, *new_name = NULL, *info = NULL;
const char *trans_name = NULL;
struct aa_perms perms = { };
unsigned int state;
int error;
AA_BUG(!profile);
AA_BUG(!new_path);
AA_BUG(!old_path);
if (profile_unconfined(profile) ||
!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
return aa_get_newest_label(&profile->label);
error = aa_path_name(old_path, path_flags(profile, old_path),
old_buffer, &old_name, &info,
profile->disconnected);
if (error)
goto audit;
error = aa_path_name(new_path, path_flags(profile, new_path),
new_buffer, &new_name, &info,
profile->disconnected);
if (error)
goto audit;
error = -EACCES;
state = aa_dfa_match(profile->policy.dfa,
profile->policy.start[AA_CLASS_MOUNT],
new_name);
state = aa_dfa_null_transition(profile->policy.dfa, state);
state = aa_dfa_match(profile->policy.dfa, state, old_name);
perms = compute_mnt_perms(profile->policy.dfa, state);
if (AA_MAY_PIVOTROOT & perms.allow)
error = 0;
audit:
error = audit_mount(profile, OP_PIVOTROOT, new_name, old_name,
NULL, trans_name, 0, NULL, AA_MAY_PIVOTROOT,
&perms, info, error);
if (error)
return ERR_PTR(error);
return aa_get_newest_label(&profile->label);
}
int aa_pivotroot(struct aa_label *label, const struct path *old_path,
const struct path *new_path)
{
struct aa_profile *profile;
struct aa_label *target = NULL;
char *old_buffer = NULL, *new_buffer = NULL, *info = NULL;
int error;
AA_BUG(!label);
AA_BUG(!old_path);
AA_BUG(!new_path);
old_buffer = aa_get_buffer(false);
new_buffer = aa_get_buffer(false);
error = -ENOMEM;
if (!old_buffer || !new_buffer)
goto out;
target = fn_label_build(label, profile, GFP_KERNEL,
build_pivotroot(profile, new_path, new_buffer,
old_path, old_buffer));
if (!target) {
info = "label build failed";
error = -ENOMEM;
goto fail;
} else if (!IS_ERR(target)) {
error = aa_replace_current_label(target);
if (error) {
/* TODO: audit target */
aa_put_label(target);
goto out;
}
} else
/* already audited error */
error = PTR_ERR(target);
out:
aa_put_buffer(old_buffer);
aa_put_buffer(new_buffer);
return error;
fail:
/* TODO: add back in auditing of new_name and old_name */
error = fn_for_each(label, profile,
audit_mount(profile, OP_PIVOTROOT, NULL /*new_name */,
NULL /* old_name */,
NULL, NULL,
0, NULL, AA_MAY_PIVOTROOT, &nullperms, info,
error));
goto out;
}