480f31c214
Changes include modifications in kernel crash dump routines, dumpon(8) and savecore(8). A new tool called decryptcore(8) was added. A new DIOCSKERNELDUMP I/O control was added to send a kernel crash dump configuration in the diocskerneldump_arg structure to the kernel. The old DIOCSKERNELDUMP I/O control was renamed to DIOCSKERNELDUMP_FREEBSD11 for backward ABI compatibility. dumpon(8) generates an one-time random symmetric key and encrypts it using an RSA public key in capability mode. Currently only AES-256-CBC is supported but EKCD was designed to implement support for other algorithms in the future. The public key is chosen using the -k flag. The dumpon rc(8) script can do this automatically during startup using the dumppubkey rc.conf(5) variable. Once the keys are calculated dumpon sends them to the kernel via DIOCSKERNELDUMP I/O control. When the kernel receives the DIOCSKERNELDUMP I/O control it generates a random IV and sets up the key schedule for the specified algorithm. Each time the kernel tries to write a crash dump to the dump device, the IV is replaced by a SHA-256 hash of the previous value. This is intended to make a possible differential cryptanalysis harder since it is possible to write multiple crash dumps without reboot by repeating the following commands: # sysctl debug.kdb.enter=1 db> call doadump(0) db> continue # savecore A kernel dump key consists of an algorithm identifier, an IV and an encrypted symmetric key. The kernel dump key size is included in a kernel dump header. The size is an unsigned 32-bit integer and it is aligned to a block size. The header structure has 512 bytes to match the block size so it was required to make a panic string 4 bytes shorter to add a new field to the header structure. If the kernel dump key size in the header is nonzero it is assumed that the kernel dump key is placed after the first header on the dump device and the core dump is encrypted. Separate functions were implemented to write the kernel dump header and the kernel dump key as they need to be unencrypted. The dump_write function encrypts data if the kernel was compiled with the EKCD option. Encrypted kernel textdumps are not supported due to the way they are constructed which makes it impossible to use the CBC mode for encryption. It should be also noted that textdumps don't contain sensitive data by design as a user decides what information should be dumped. savecore(8) writes the kernel dump key to a key.# file if its size in the header is nonzero. # is the number of the current core dump. decryptcore(8) decrypts the core dump using a private RSA key and the kernel dump key. This is performed by a child process in capability mode. If the decryption was not successful the parent process removes a partially decrypted core dump. Description on how to encrypt crash dumps was added to the decryptcore(8), dumpon(8), rc.conf(5) and savecore(8) manual pages. EKCD was tested on amd64 using bhyve and i386, mipsel and sparc64 using QEMU. The feature still has to be tested on arm and arm64 as it wasn't possible to run FreeBSD due to the problems with QEMU emulation and lack of hardware. Designed by: def, pjd Reviewed by: cem, oshogbo, pjd Partial review: delphij, emaste, jhb, kib Approved by: pjd (mentor) Differential Revision: https://reviews.freebsd.org/D4712
155 lines
4.9 KiB
C
155 lines
4.9 KiB
C
/*-
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* Copyright (c) 2002 Poul-Henning Kamp
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* Copyright (c) 2002 Networks Associates Technology, Inc.
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* All rights reserved.
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*
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* This software was developed for the FreeBSD Project by Poul-Henning Kamp
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* and NAI Labs, the Security Research Division of Network Associates, Inc.
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* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
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* DARPA CHATS research program.
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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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* 3. The names of the authors may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, 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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* $FreeBSD$
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*/
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#ifndef _SYS_KERNELDUMP_H
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#define _SYS_KERNELDUMP_H
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#include <sys/param.h>
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#include <sys/conf.h>
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#include <machine/endian.h>
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#if BYTE_ORDER == LITTLE_ENDIAN
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#define dtoh32(x) __bswap32(x)
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#define dtoh64(x) __bswap64(x)
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#define htod32(x) __bswap32(x)
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#define htod64(x) __bswap64(x)
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#elif BYTE_ORDER == BIG_ENDIAN
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#define dtoh32(x) (x)
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#define dtoh64(x) (x)
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#define htod32(x) (x)
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#define htod64(x) (x)
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#endif
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#define KERNELDUMP_ENC_NONE 0
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#define KERNELDUMP_ENC_AES_256_CBC 1
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#define KERNELDUMP_BUFFER_SIZE 1024
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#define KERNELDUMP_IV_MAX_SIZE 32
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#define KERNELDUMP_KEY_MAX_SIZE 64
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#define KERNELDUMP_ENCKEY_MAX_SIZE (16384 / 8)
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/*
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* All uintX_t fields are in dump byte order, which is the same as
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* network byte order. Use the macros defined above to read or
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* write the fields.
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*/
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struct kerneldumpheader {
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char magic[20];
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#define KERNELDUMPMAGIC "FreeBSD Kernel Dump"
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#define TEXTDUMPMAGIC "FreeBSD Text Dump"
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#define KERNELDUMPMAGIC_CLEARED "Cleared Kernel Dump"
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char architecture[12];
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uint32_t version;
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#define KERNELDUMPVERSION 2
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#define KERNELDUMP_TEXT_VERSION 2
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uint32_t architectureversion;
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#define KERNELDUMP_AARCH64_VERSION 1
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#define KERNELDUMP_AMD64_VERSION 2
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#define KERNELDUMP_ARM_VERSION 1
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#define KERNELDUMP_I386_VERSION 2
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#define KERNELDUMP_MIPS_VERSION 1
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#define KERNELDUMP_POWERPC_VERSION 1
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#define KERNELDUMP_RISCV_VERSION 1
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#define KERNELDUMP_SPARC64_VERSION 1
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uint64_t dumplength; /* excl headers */
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uint64_t dumptime;
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uint32_t dumpkeysize;
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uint32_t blocksize;
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char hostname[64];
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char versionstring[192];
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char panicstring[188];
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uint32_t parity;
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};
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struct kerneldumpkey {
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uint8_t kdk_encryption;
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uint8_t kdk_iv[KERNELDUMP_IV_MAX_SIZE];
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uint32_t kdk_encryptedkeysize;
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uint8_t kdk_encryptedkey[];
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} __packed;
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/*
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* Parity calculation is endian insensitive.
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*/
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static __inline u_int32_t
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kerneldump_parity(struct kerneldumpheader *kdhp)
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{
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uint32_t *up, parity;
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u_int i;
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up = (uint32_t *)kdhp;
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parity = 0;
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for (i = 0; i < sizeof *kdhp; i += sizeof *up)
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parity ^= *up++;
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return (parity);
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}
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#ifdef _KERNEL
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struct dump_pa {
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vm_paddr_t pa_start;
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vm_paddr_t pa_size;
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};
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int kerneldumpcrypto_init(struct kerneldumpcrypto *kdc);
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uint32_t kerneldumpcrypto_dumpkeysize(const struct kerneldumpcrypto *kdc);
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void mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
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uint64_t dumplen, uint32_t dumpkeysize, uint32_t blksz);
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int dumpsys_generic(struct dumperinfo *);
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void dumpsys_map_chunk(vm_paddr_t, size_t, void **);
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typedef int dumpsys_callback_t(struct dump_pa *, int, void *);
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int dumpsys_foreach_chunk(dumpsys_callback_t, void *);
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int dumpsys_cb_dumpdata(struct dump_pa *, int, void *);
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int dumpsys_buf_seek(struct dumperinfo *, size_t);
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int dumpsys_buf_write(struct dumperinfo *, char *, size_t);
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int dumpsys_buf_flush(struct dumperinfo *);
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void dumpsys_gen_pa_init(void);
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struct dump_pa *dumpsys_gen_pa_next(struct dump_pa *);
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void dumpsys_gen_wbinv_all(void);
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void dumpsys_gen_unmap_chunk(vm_paddr_t, size_t, void *);
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int dumpsys_gen_write_aux_headers(struct dumperinfo *);
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extern int do_minidump;
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#endif
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#endif /* _SYS_KERNELDUMP_H */
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