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/*
* Copyright (c) 2015 Dmitry V. Levin <ldv@altlinux.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "defs.h"
#ifdef HAVE_LINUX_SECCOMP_H
# include <linux/seccomp.h>
#endif
#include "xlat/seccomp_ops.h"
#include "xlat/seccomp_filter_flags.h"
#ifdef HAVE_LINUX_FILTER_H
# include <linux/filter.h>
# include "xlat/bpf_class.h"
# include "xlat/bpf_miscop.h"
# include "xlat/bpf_mode.h"
# include "xlat/bpf_op_alu.h"
# include "xlat/bpf_op_jmp.h"
# include "xlat/bpf_rval.h"
# include "xlat/bpf_size.h"
# include "xlat/bpf_src.h"
# ifndef SECCOMP_RET_ACTION
# define SECCOMP_RET_ACTION 0x7fff0000U
# endif
# include "xlat/seccomp_ret_action.h"
#endif
struct bpf_filter {
uint16_t code;
uint8_t jt;
uint8_t jf;
uint32_t k;
};
#ifdef HAVE_LINUX_FILTER_H
static void
decode_bpf_code(uint16_t code)
{
uint16_t i = code & ~BPF_CLASS(code);
printxval(bpf_class, BPF_CLASS(code), "BPF_???");
switch (BPF_CLASS(code)) {
case BPF_LD:
case BPF_LDX:
tprints("|");
printxval(bpf_size, BPF_SIZE(code), "BPF_???");
tprints("|");
printxval(bpf_mode, BPF_MODE(code), "BPF_???");
break;
case BPF_ST:
case BPF_STX:
if (i)
tprintf("|%#x /* %s */", i, "BPF_???");
break;
case BPF_ALU:
tprints("|");
printxval(bpf_src, BPF_SRC(code), "BPF_???");
tprints("|");
printxval(bpf_op_alu, BPF_OP(code), "BPF_???");
break;
case BPF_JMP:
tprints("|");
printxval(bpf_src, BPF_SRC(code), "BPF_???");
tprints("|");
printxval(bpf_op_jmp, BPF_OP(code), "BPF_???");
break;
case BPF_RET:
tprints("|");
printxval(bpf_rval, BPF_RVAL(code), "BPF_???");
i &= ~BPF_RVAL(code);
if (i)
tprintf("|%#x /* %s */", i, "BPF_???");
break;
case BPF_MISC:
tprints("|");
printxval(bpf_miscop, BPF_MISCOP(code), "BPF_???");
i &= ~BPF_MISCOP(code);
if (i)
tprintf("|%#x /* %s */", i, "BPF_???");
break;
}
}
#endif /* HAVE_LINUX_FILTER_H */
static void
decode_bpf_stmt(const struct bpf_filter *filter)
{
#ifdef HAVE_LINUX_FILTER_H
tprints("BPF_STMT(");
decode_bpf_code(filter->code);
tprints(", ");
if (BPF_CLASS(filter->code) == BPF_RET) {
unsigned int action = SECCOMP_RET_ACTION & filter->k;
unsigned int data = filter->k & ~action;
printxval(seccomp_ret_action, action, "SECCOMP_RET_???");
if (data)
tprintf("|%#x)", data);
else
tprints(")");
} else {
tprintf("%#x)", filter->k);
}
#else
tprintf("BPF_STMT(%#x, %#x)", filter->code, filter->k);
#endif /* HAVE_LINUX_FILTER_H */
}
static void
decode_bpf_jump(const struct bpf_filter *filter)
{
#ifdef HAVE_LINUX_FILTER_H
tprints("BPF_JUMP(");
decode_bpf_code(filter->code);
tprintf(", %#x, %#x, %#x)",
filter->k, filter->jt, filter->jf);
#else
tprintf("BPF_JUMP(%#x, %#x, %#x, %#x)",
filter->code, filter->k, filter->jt, filter->jf);
#endif /* HAVE_LINUX_FILTER_H */
}
#ifndef BPF_MAXINSNS
# define BPF_MAXINSNS 4096
#endif
static bool
print_bpf_filter(struct tcb *tcp, void *elem_buf, size_t elem_size, void *data)
{
const struct bpf_filter *filter = elem_buf;
unsigned int *pn = data;
if ((*pn)++ >= BPF_MAXINSNS) {
tprints("...");
return false;
}
if (filter->jt || filter->jf)
decode_bpf_jump(filter);
else
decode_bpf_stmt(filter);
return true;
}
static void
print_seccomp_fprog(struct tcb *tcp, unsigned long addr, unsigned short len)
{
tprintf("{len=%u, filter=", len);
if (abbrev(tcp)) {
printaddr(addr);
} else {
unsigned int insns = 0;
struct bpf_filter filter;
print_array(tcp, addr, len, &filter, sizeof(filter),
umoven_or_printaddr, print_bpf_filter, &insns);
}
tprints("}");
}
#include "seccomp_fprog.h"
void
print_seccomp_filter(struct tcb *tcp, unsigned long addr)
{
struct seccomp_fprog fprog;
if (fetch_seccomp_fprog(tcp, addr, &fprog))
print_seccomp_fprog(tcp, fprog.filter, fprog.len);
}
static void
decode_seccomp_set_mode_strict(unsigned int flags, unsigned long addr)
{
tprintf("%u, ", flags);
printaddr(addr);
}
SYS_FUNC(seccomp)
{
unsigned int op = tcp->u_arg[0];
printxval(seccomp_ops, op, "SECCOMP_SET_MODE_???");
tprints(", ");
if (op == SECCOMP_SET_MODE_FILTER) {
printflags(seccomp_filter_flags, tcp->u_arg[1],
"SECCOMP_FILTER_FLAG_???");
tprints(", ");
print_seccomp_filter(tcp, tcp->u_arg[2]);
} else {
decode_seccomp_set_mode_strict(tcp->u_arg[1],
tcp->u_arg[2]);
}
return RVAL_DECODED;
}
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