![John Johansen](/assets/img/avatar_default.png)
When the mount code was refactored for Labels it was not correctly
updated to check whether policy supported mediation of the mount
class. This causes a regression when the kernel feature set is
reported as supporting mount and policy is pinned to a feature set
that does not support mount mediation.
BugLink: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=882697#41
Fixes: 2ea3ffb778
("apparmor: add mount mediation")
Reported-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John Johansen <john.johansen@canonical.com>
706 lines
18 KiB
C
706 lines
18 KiB
C
/*
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* AppArmor security module
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*
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* This file contains AppArmor mediation of files
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*
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* Copyright (C) 1998-2008 Novell/SUSE
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* Copyright 2009-2017 Canonical Ltd.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*/
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/namei.h>
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#include "include/apparmor.h"
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#include "include/audit.h"
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#include "include/context.h"
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#include "include/domain.h"
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#include "include/file.h"
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#include "include/match.h"
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#include "include/mount.h"
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#include "include/path.h"
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#include "include/policy.h"
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static void audit_mnt_flags(struct audit_buffer *ab, unsigned long flags)
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{
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if (flags & MS_RDONLY)
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audit_log_format(ab, "ro");
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else
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audit_log_format(ab, "rw");
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if (flags & MS_NOSUID)
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audit_log_format(ab, ", nosuid");
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if (flags & MS_NODEV)
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audit_log_format(ab, ", nodev");
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if (flags & MS_NOEXEC)
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audit_log_format(ab, ", noexec");
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if (flags & MS_SYNCHRONOUS)
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audit_log_format(ab, ", sync");
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if (flags & MS_REMOUNT)
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audit_log_format(ab, ", remount");
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if (flags & MS_MANDLOCK)
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audit_log_format(ab, ", mand");
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if (flags & MS_DIRSYNC)
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audit_log_format(ab, ", dirsync");
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if (flags & MS_NOATIME)
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audit_log_format(ab, ", noatime");
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if (flags & MS_NODIRATIME)
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audit_log_format(ab, ", nodiratime");
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if (flags & MS_BIND)
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audit_log_format(ab, flags & MS_REC ? ", rbind" : ", bind");
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if (flags & MS_MOVE)
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audit_log_format(ab, ", move");
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if (flags & MS_SILENT)
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audit_log_format(ab, ", silent");
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if (flags & MS_POSIXACL)
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audit_log_format(ab, ", acl");
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if (flags & MS_UNBINDABLE)
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audit_log_format(ab, flags & MS_REC ? ", runbindable" :
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", unbindable");
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if (flags & MS_PRIVATE)
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audit_log_format(ab, flags & MS_REC ? ", rprivate" :
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", private");
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if (flags & MS_SLAVE)
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audit_log_format(ab, flags & MS_REC ? ", rslave" :
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", slave");
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if (flags & MS_SHARED)
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audit_log_format(ab, flags & MS_REC ? ", rshared" :
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", shared");
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if (flags & MS_RELATIME)
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audit_log_format(ab, ", relatime");
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if (flags & MS_I_VERSION)
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audit_log_format(ab, ", iversion");
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if (flags & MS_STRICTATIME)
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audit_log_format(ab, ", strictatime");
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if (flags & MS_NOUSER)
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audit_log_format(ab, ", nouser");
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}
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/**
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* audit_cb - call back for mount specific audit fields
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* @ab: audit_buffer (NOT NULL)
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* @va: audit struct to audit values of (NOT NULL)
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*/
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static void audit_cb(struct audit_buffer *ab, void *va)
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{
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struct common_audit_data *sa = va;
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if (aad(sa)->mnt.type) {
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audit_log_format(ab, " fstype=");
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audit_log_untrustedstring(ab, aad(sa)->mnt.type);
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}
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if (aad(sa)->mnt.src_name) {
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audit_log_format(ab, " srcname=");
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audit_log_untrustedstring(ab, aad(sa)->mnt.src_name);
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}
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if (aad(sa)->mnt.trans) {
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audit_log_format(ab, " trans=");
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audit_log_untrustedstring(ab, aad(sa)->mnt.trans);
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}
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if (aad(sa)->mnt.flags) {
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audit_log_format(ab, " flags=\"");
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audit_mnt_flags(ab, aad(sa)->mnt.flags);
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audit_log_format(ab, "\"");
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}
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if (aad(sa)->mnt.data) {
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audit_log_format(ab, " options=");
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audit_log_untrustedstring(ab, aad(sa)->mnt.data);
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}
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}
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/**
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* audit_mount - handle the auditing of mount operations
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* @profile: the profile being enforced (NOT NULL)
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* @op: operation being mediated (NOT NULL)
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* @name: name of object being mediated (MAYBE NULL)
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* @src_name: src_name of object being mediated (MAYBE_NULL)
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* @type: type of filesystem (MAYBE_NULL)
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* @trans: name of trans (MAYBE NULL)
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* @flags: filesystem idependent mount flags
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* @data: filesystem mount flags
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* @request: permissions requested
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* @perms: the permissions computed for the request (NOT NULL)
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* @info: extra information message (MAYBE NULL)
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* @error: 0 if operation allowed else failure error code
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*
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* Returns: %0 or error on failure
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*/
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static int audit_mount(struct aa_profile *profile, const char *op,
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const char *name, const char *src_name,
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const char *type, const char *trans,
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unsigned long flags, const void *data, u32 request,
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struct aa_perms *perms, const char *info, int error)
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{
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int audit_type = AUDIT_APPARMOR_AUTO;
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DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, op);
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if (likely(!error)) {
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u32 mask = perms->audit;
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if (unlikely(AUDIT_MODE(profile) == AUDIT_ALL))
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mask = 0xffff;
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/* mask off perms that are not being force audited */
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request &= mask;
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if (likely(!request))
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return 0;
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audit_type = AUDIT_APPARMOR_AUDIT;
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} else {
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/* only report permissions that were denied */
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request = request & ~perms->allow;
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if (request & perms->kill)
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audit_type = AUDIT_APPARMOR_KILL;
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/* quiet known rejects, assumes quiet and kill do not overlap */
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if ((request & perms->quiet) &&
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AUDIT_MODE(profile) != AUDIT_NOQUIET &&
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AUDIT_MODE(profile) != AUDIT_ALL)
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request &= ~perms->quiet;
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if (!request)
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return error;
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}
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aad(&sa)->name = name;
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aad(&sa)->mnt.src_name = src_name;
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aad(&sa)->mnt.type = type;
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aad(&sa)->mnt.trans = trans;
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aad(&sa)->mnt.flags = flags;
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if (data && (perms->audit & AA_AUDIT_DATA))
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aad(&sa)->mnt.data = data;
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aad(&sa)->info = info;
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aad(&sa)->error = error;
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return aa_audit(audit_type, profile, &sa, audit_cb);
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}
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/**
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* match_mnt_flags - Do an ordered match on mount flags
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* @dfa: dfa to match against
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* @state: state to start in
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* @flags: mount flags to match against
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*
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* Mount flags are encoded as an ordered match. This is done instead of
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* checking against a simple bitmask, to allow for logical operations
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* on the flags.
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*
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* Returns: next state after flags match
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*/
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static unsigned int match_mnt_flags(struct aa_dfa *dfa, unsigned int state,
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unsigned long flags)
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{
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unsigned int i;
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for (i = 0; i <= 31 ; ++i) {
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if ((1 << i) & flags)
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state = aa_dfa_next(dfa, state, i + 1);
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}
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return state;
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}
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/**
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* compute_mnt_perms - compute mount permission associated with @state
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* @dfa: dfa to match against (NOT NULL)
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* @state: state match finished in
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*
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* Returns: mount permissions
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*/
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static struct aa_perms compute_mnt_perms(struct aa_dfa *dfa,
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unsigned int state)
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{
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struct aa_perms perms = {
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.allow = dfa_user_allow(dfa, state),
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.audit = dfa_user_audit(dfa, state),
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.quiet = dfa_user_quiet(dfa, state),
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.xindex = dfa_user_xindex(dfa, state),
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};
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return perms;
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}
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static const char * const mnt_info_table[] = {
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"match succeeded",
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"failed mntpnt match",
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"failed srcname match",
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"failed type match",
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"failed flags match",
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"failed data match"
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};
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/*
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* Returns 0 on success else element that match failed in, this is the
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* index into the mnt_info_table above
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*/
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static int do_match_mnt(struct aa_dfa *dfa, unsigned int start,
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const char *mntpnt, const char *devname,
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const char *type, unsigned long flags,
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void *data, bool binary, struct aa_perms *perms)
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{
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unsigned int state;
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AA_BUG(!dfa);
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AA_BUG(!perms);
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state = aa_dfa_match(dfa, start, mntpnt);
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state = aa_dfa_null_transition(dfa, state);
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if (!state)
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return 1;
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if (devname)
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state = aa_dfa_match(dfa, state, devname);
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state = aa_dfa_null_transition(dfa, state);
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if (!state)
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return 2;
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if (type)
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state = aa_dfa_match(dfa, state, type);
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state = aa_dfa_null_transition(dfa, state);
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if (!state)
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return 3;
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state = match_mnt_flags(dfa, state, flags);
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if (!state)
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return 4;
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*perms = compute_mnt_perms(dfa, state);
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if (perms->allow & AA_MAY_MOUNT)
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return 0;
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/* only match data if not binary and the DFA flags data is expected */
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if (data && !binary && (perms->allow & AA_MNT_CONT_MATCH)) {
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state = aa_dfa_null_transition(dfa, state);
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if (!state)
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return 4;
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state = aa_dfa_match(dfa, state, data);
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if (!state)
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return 5;
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*perms = compute_mnt_perms(dfa, state);
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if (perms->allow & AA_MAY_MOUNT)
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return 0;
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}
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/* failed at end of flags match */
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return 4;
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}
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static int path_flags(struct aa_profile *profile, const struct path *path)
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{
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AA_BUG(!profile);
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AA_BUG(!path);
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return profile->path_flags |
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(S_ISDIR(path->dentry->d_inode->i_mode) ? PATH_IS_DIR : 0);
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}
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/**
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* match_mnt_path_str - handle path matching for mount
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* @profile: the confining profile
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* @mntpath: for the mntpnt (NOT NULL)
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* @buffer: buffer to be used to lookup mntpath
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* @devnme: string for the devname/src_name (MAY BE NULL OR ERRPTR)
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* @type: string for the dev type (MAYBE NULL)
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* @flags: mount flags to match
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* @data: fs mount data (MAYBE NULL)
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* @binary: whether @data is binary
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* @devinfo: error str if (IS_ERR(@devname))
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*
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* Returns: 0 on success else error
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*/
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static int match_mnt_path_str(struct aa_profile *profile,
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const struct path *mntpath, char *buffer,
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const char *devname, const char *type,
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unsigned long flags, void *data, bool binary,
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const char *devinfo)
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{
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struct aa_perms perms = { };
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const char *mntpnt = NULL, *info = NULL;
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int pos, error;
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AA_BUG(!profile);
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AA_BUG(!mntpath);
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AA_BUG(!buffer);
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if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
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return 0;
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error = aa_path_name(mntpath, path_flags(profile, mntpath), buffer,
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&mntpnt, &info, profile->disconnected);
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if (error)
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goto audit;
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if (IS_ERR(devname)) {
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error = PTR_ERR(devname);
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devname = NULL;
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info = devinfo;
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goto audit;
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}
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error = -EACCES;
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pos = do_match_mnt(profile->policy.dfa,
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profile->policy.start[AA_CLASS_MOUNT],
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mntpnt, devname, type, flags, data, binary, &perms);
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if (pos) {
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info = mnt_info_table[pos];
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goto audit;
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}
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error = 0;
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audit:
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return audit_mount(profile, OP_MOUNT, mntpnt, devname, type, NULL,
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flags, data, AA_MAY_MOUNT, &perms, info, error);
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}
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/**
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* match_mnt - handle path matching for mount
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* @profile: the confining profile
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* @mntpath: for the mntpnt (NOT NULL)
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* @buffer: buffer to be used to lookup mntpath
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* @devpath: path devname/src_name (MAYBE NULL)
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* @devbuffer: buffer to be used to lookup devname/src_name
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* @type: string for the dev type (MAYBE NULL)
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* @flags: mount flags to match
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* @data: fs mount data (MAYBE NULL)
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* @binary: whether @data is binary
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*
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* Returns: 0 on success else error
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*/
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static int match_mnt(struct aa_profile *profile, const struct path *path,
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char *buffer, struct path *devpath, char *devbuffer,
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const char *type, unsigned long flags, void *data,
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bool binary)
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{
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const char *devname = NULL, *info = NULL;
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int error = -EACCES;
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AA_BUG(!profile);
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AA_BUG(devpath && !devbuffer);
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if (!PROFILE_MEDIATES(profile, AA_CLASS_MOUNT))
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return 0;
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if (devpath) {
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error = aa_path_name(devpath, path_flags(profile, devpath),
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devbuffer, &devname, &info,
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profile->disconnected);
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if (error)
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devname = ERR_PTR(error);
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}
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return match_mnt_path_str(profile, path, buffer, devname, type, flags,
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data, binary, info);
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}
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int aa_remount(struct aa_label *label, const struct path *path,
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unsigned long flags, void *data)
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{
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struct aa_profile *profile;
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char *buffer = NULL;
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bool binary;
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int error;
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AA_BUG(!label);
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AA_BUG(!path);
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binary = path->dentry->d_sb->s_type->fs_flags & FS_BINARY_MOUNTDATA;
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get_buffers(buffer);
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error = fn_for_each_confined(label, profile,
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match_mnt(profile, path, buffer, NULL, NULL, NULL,
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flags, data, binary));
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put_buffers(buffer);
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return error;
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}
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int aa_bind_mount(struct aa_label *label, const struct path *path,
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const char *dev_name, unsigned long flags)
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{
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struct aa_profile *profile;
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char *buffer = NULL, *old_buffer = NULL;
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struct path old_path;
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int error;
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AA_BUG(!label);
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AA_BUG(!path);
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if (!dev_name || !*dev_name)
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return -EINVAL;
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flags &= MS_REC | MS_BIND;
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error = kern_path(dev_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
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if (error)
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return error;
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get_buffers(buffer, old_buffer);
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error = fn_for_each_confined(label, profile,
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match_mnt(profile, path, buffer, &old_path, old_buffer,
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NULL, flags, NULL, false));
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put_buffers(buffer, old_buffer);
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path_put(&old_path);
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return error;
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}
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int aa_mount_change_type(struct aa_label *label, const struct path *path,
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unsigned long flags)
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{
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struct aa_profile *profile;
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char *buffer = NULL;
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int error;
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AA_BUG(!label);
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AA_BUG(!path);
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/* These are the flags allowed by do_change_type() */
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flags &= (MS_REC | MS_SILENT | MS_SHARED | MS_PRIVATE | MS_SLAVE |
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MS_UNBINDABLE);
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get_buffers(buffer);
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error = fn_for_each_confined(label, profile,
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match_mnt(profile, path, buffer, NULL, NULL, NULL,
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flags, NULL, false));
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put_buffers(buffer);
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return error;
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}
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int aa_move_mount(struct aa_label *label, const struct path *path,
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const char *orig_name)
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{
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struct aa_profile *profile;
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char *buffer = NULL, *old_buffer = NULL;
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struct path old_path;
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int error;
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AA_BUG(!label);
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AA_BUG(!path);
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if (!orig_name || !*orig_name)
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return -EINVAL;
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error = kern_path(orig_name, LOOKUP_FOLLOW, &old_path);
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if (error)
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return error;
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get_buffers(buffer, old_buffer);
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error = fn_for_each_confined(label, profile,
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match_mnt(profile, path, buffer, &old_path, old_buffer,
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NULL, MS_MOVE, NULL, false));
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put_buffers(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;
|
|
}
|
|
}
|
|
|
|
get_buffers(buffer, dev_buffer);
|
|
if (dev_path) {
|
|
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));
|
|
}
|
|
put_buffers(buffer, dev_buffer);
|
|
if (dev_path)
|
|
path_put(dev_path);
|
|
|
|
return error;
|
|
}
|
|
|
|
static int profile_umount(struct aa_profile *profile, 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);
|
|
|
|
get_buffers(buffer);
|
|
error = fn_for_each_confined(label, profile,
|
|
profile_umount(profile, &path, buffer));
|
|
put_buffers(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);
|
|
|
|
get_buffers(old_buffer, new_buffer);
|
|
target = fn_label_build(label, profile, GFP_ATOMIC,
|
|
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:
|
|
put_buffers(old_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;
|
|
}
|