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framework. The code is organized into a few distinct pieces: * The meta-data store (in veriexec_metadata.c) which maps a file system identifier, file identifier, and generation key tuple to veriexec meta-data record. * Fingerprint management (in veriexec_fingerprint.c) which deals with calculating the cryptographic hash for a file and verifying it. It also manages the loadable fingerprint modules. * MAC policy implementation (in mac_veriexec.c) which implements the following MAC methods: mpo_init Initializes the veriexec state, meta-data store, fingerprint modules, and registers mount and unmount EVENTHANDLERs mpo_syscall Implements the following per-policy system calls: MAC_VERIEXEC_CHECK_FD_SYSCALL Check a file descriptor to see if the referenced file has a valid fingerprint. MAC_VERIEXEC_CHECK_PATH_SYSCALL Check a path to see if the referenced file has a valid fingerprint. mpo_kld_check_load Check if loading a kld is allowed. This checks if the referenced vnode has a valid fingerprint. mpo_mount_destroy_label Clears the veriexec slot data in a mount point label. mpo_mount_init_label Initializes the veriexec slot data in a mount point label. The file system identifier is saved in the veriexec slot data. mpo_priv_check Check if a process is allowed to write to /dev/kmem and /dev/mem devices. If a process is flagged as trusted, it is allowed to write. mpo_proc_check_debug Check if a process is allowed to be debugged. If a process is not flagged with VERIEXEC_NOTRACE, then debugging is allowed. mpo_vnode_check_exec Check is an exectuable is allowed to run. If veriexec is not enforcing or the executable has a valid fingerprint, then it is allowed to run. NOTE: veriexec will complain about mismatched fingerprints if it is active, regardless of the state of the enforcement. mpo_vnode_check_open Check is a file is allowed to be opened. If verification was not requested, veriexec is not enforcing, or the file has a valid fingerprint, then veriexec will allow the file to be opened. mpo_vnode_copy_label Copies the veriexec slot data from one label to another. mpo_vnode_destroy_label Clears the veriexec slot data in a vnode label. mpo_vnode_init_label Initializes the veriexec slot data in a vnode label. The fingerprint status for the file is stored in the veriexec slot data. * Some sysctls, under security.mac.veriexec, for setting debug level, fetching the current state in a human-readable form, and dumping the fingerprint database are implemented. * The MAC policy implementation source file also contains some utility functions. * A set of fingerprint modules for the following cryptographic hash algorithms: RIPEMD-160, SHA1, SHA2-256, SHA2-384, SHA2-512 * Loadable module builds for MAC/veriexec and fingerprint modules. WARNING: Using veriexec with NFS (or other network-based) file systems is not recommended as one cannot guarantee the integrity of the files served, nor the uniqueness of file system identifiers which are used as key in the meta-data store. Reviewed by: ian, jtl Obtained from: Juniper Networks, Inc. Differential Revision: https://reviews.freebsd.org/D8554
162 lines
5.8 KiB
C
162 lines
5.8 KiB
C
/*
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* $FreeBSD$
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*
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* Copyright (c) 2011, 2012, 2013, 2015, 2016, Juniper Networks, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _SECURITY_MAC_VERIEXEC_H
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#define _SECURITY_MAC_VERIEXEC_H
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#ifdef _KERNEL
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#include <sys/types.h>
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#include <sys/kernel.h>
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#include <sys/queue.h>
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#include <sys/module.h>
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#endif
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/**
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* Name of the MAC module
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*/
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#define MAC_VERIEXEC_NAME "mac_veriexec"
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/* MAC/veriexec syscalls */
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#define MAC_VERIEXEC_CHECK_FD_SYSCALL 1
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#define MAC_VERIEXEC_CHECK_PATH_SYSCALL 2
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/**
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* Enough room for the largest signature...
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*/
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#define MAXFINGERPRINTLEN 64 /* enough room for largest signature */
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/*
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* Types of veriexec inodes we can have
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*/
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#define VERIEXEC_INDIRECT (1<<0) /* Only allow indirect execution */
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#define VERIEXEC_FILE (1<<1) /* Fingerprint of a plain file */
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#define VERIEXEC_NOTRACE (1<<2) /**< PTRACE not allowed */
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#define VERIEXEC_TRUSTED (1<<3) /**< Safe to write /dev/mem */
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/* XXX these are currently unimplemented */
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#define VERIEXEC_NOFIPS (1<<4) /**< Not allowed in FIPS mode */
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#define VERIEXEC_STATE_INACTIVE 0 /**< Ignore */
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#define VERIEXEC_STATE_LOADED (1<<0) /**< Sigs have been loaded */
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#define VERIEXEC_STATE_ACTIVE (1<<1) /**< Pay attention to it */
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#define VERIEXEC_STATE_ENFORCE (1<<2) /**< Fail execs for files that do not
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match signature */
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#define VERIEXEC_STATE_LOCKED (1<<3) /**< Do not allow further changes */
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#ifdef _KERNEL
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/**
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* Version of the MAC/veriexec module
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*/
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#define MAC_VERIEXEC_VERSION 1
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/* Valid states for the fingerprint flag - if signed exec is being used */
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typedef enum fingerprint_status {
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FINGERPRINT_INVALID, /**< Fingerprint has not been evaluated */
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FINGERPRINT_VALID, /**< Fingerprint evaluated and matches list */
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FINGERPRINT_INDIRECT, /**< Fingerprint eval'd/matched but only
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indirect execs allowed */
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FINGERPRINT_FILE, /**< Fingerprint evaluated/matched but
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not executable */
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FINGERPRINT_NOMATCH, /**< Fingerprint evaluated but does not match */
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FINGERPRINT_NOENTRY, /**< Fingerprint evaluated but no list entry */
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FINGERPRINT_NODEV, /**< Fingerprint evaluated but no dev list */
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} fingerprint_status_t;
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typedef void (*mac_veriexec_fpop_init_t)(void *);
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typedef void (*mac_veriexec_fpop_update_t)(void *, const uint8_t *, size_t);
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typedef void (*mac_veriexec_fpop_final_t)(uint8_t *, void *);
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struct mac_veriexec_fpops {
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const char *type;
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size_t digest_len;
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size_t context_size;
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mac_veriexec_fpop_init_t init;
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mac_veriexec_fpop_update_t update;
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mac_veriexec_fpop_final_t final;
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LIST_ENTRY(mac_veriexec_fpops) entries;
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};
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/**
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* Verified execution subsystem debugging level
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*/
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extern int mac_veriexec_debug;
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/**
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* @brief Define a fingerprint module.
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*
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* @param _name Name of the fingerprint module
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* @param _digest_len Length of the digest string, in number of characters
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* @param _context_size Size of the context structure, in bytes
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* @param _init Initialization function of type
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* mac_veriexec_fpop_init_t
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* @param _update Update function of type mac_veriexec_fpop_update_t
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* @param _final Finalize function of type mac_veriexec_fpop_final_t
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* @param _vers Module version
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*/
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#define MAC_VERIEXEC_FPMOD(_name, _digest_len, _context_size, _init, \
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_update, _final, _vers) \
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static struct mac_veriexec_fpops \
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mac_veriexec_##_name##_fpops = { \
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.type = #_name, \
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.digest_len = _digest_len, \
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.context_size = _context_size, \
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.init = _init, \
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.update = _update, \
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.final = _final, \
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}; \
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static moduledata_t mac_veriexec_##_name##_mod = { \
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"mac_veriexec/" #_name, \
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mac_veriexec_fingerprint_modevent, \
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&(mac_veriexec_##_name##_fpops) \
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}; \
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MODULE_VERSION(mac_veriexec_##_name, _vers); \
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DECLARE_MODULE(mac_veriexec_##_name, \
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mac_veriexec_##_name##_mod, SI_SUB_MAC_POLICY, \
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SI_ORDER_ANY); \
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MODULE_DEPEND(mac_veriexec_##_name, mac_veriexec, \
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MAC_VERIEXEC_VERSION, MAC_VERIEXEC_VERSION, \
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MAC_VERIEXEC_VERSION)
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/*
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* The following function should not be called directly. The prototype is
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* included here to satisfy the compiler when using the macro above.
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*/
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int mac_veriexec_fingerprint_modevent(module_t mod, int type, void *data);
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/*
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* Public functions
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*/
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int mac_veriexec_metadata_add_file(int file_dev, dev_t fsid, long fileid,
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unsigned long gen, unsigned char fingerprint[MAXFINGERPRINTLEN],
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int flags, const char *fp_type, int override);
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int mac_veriexec_metadata_has_file(dev_t fsid, long fileid,
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unsigned long gen);
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int mac_veriexec_proc_is_trusted(struct ucred *cred, struct proc *p);
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#endif
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#endif /* _SECURITY_MAC_VERIEXEC_H */
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