Unix/Darwin/paranoia.cpp

/*
 *  paranoia.cpp - Check undocumented features of the Darwin kernel that
 *                 SheepShaver relies upon
 *
 *  SheepShaver (C) 1997-2005 Christian Bauer and Marc Hellwig
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/ucontext.h>

#include "sysdeps.h"
#include "main.h"
#include "user_strings.h"

#define DEBUG 1
#include "debug.h"


// Constants
const uint32 SIG_STACK_SIZE = 0x10000;          // Size of signal stack

// Prototypes
extern "C" int sigaltstack(const struct sigaltstack *ss, struct sigaltstack *oss);
extern "C" void *get_sp(void);
extern "C" void set_r2(uint32 val);
extern void paranoia_check(void);
static void sigusr2_handler(int sig, siginfo_t *sip, void *scp);

// Global variables
static void *sig_stack = NULL;

static int err = 0;
static void *sig_sp = NULL;
static void *sig_r4 = NULL;
static int sig_sc_signal = 0;
static void *sig_sc_regs = NULL;
static uint32 sig_r2 = 0;


void paranoia_check(void)
{
        char str[256];

        D(bug("Paranoia checks...\n"));

        // Create and install stack for signal handler
        sig_stack = malloc(SIG_STACK_SIZE);
        if (sig_stack == NULL) {
                ErrorAlert(GetString(STR_NOT_ENOUGH_MEMORY_ERR));
                exit(1);
        }

        struct sigaltstack old_stack;
        struct sigaltstack new_stack;
        new_stack.ss_sp = (char *)sig_stack;
        new_stack.ss_flags = 0;
        new_stack.ss_size = SIG_STACK_SIZE;
        if (sigaltstack(&new_stack, &old_stack) < 0) {
                sprintf(str, GetString(STR_SIGALTSTACK_ERR), strerror(errno));
                ErrorAlert(str);
                exit(1);
        }

        // Install SIGUSR2 signal handler
        static struct sigaction old_action;
        static struct sigaction sigusr2_action;
        sigemptyset(&sigusr2_action.sa_mask);
        sigusr2_action.sa_sigaction = sigusr2_handler;
        sigusr2_action.sa_flags = SA_ONSTACK | SA_RESTART | SA_SIGINFO;
        if (sigaction(SIGUSR2, &sigusr2_action, &old_action) < 0) {
                sprintf(str, GetString(STR_SIGUSR2_INSTALL_ERR), strerror(errno));
                ErrorAlert(str);
                exit(1);
        }

        // Raise SIGUSR2
        set_r2(0xaffebad5);
        raise(SIGUSR2);

        // Check error code
        switch (err) {
                case 1:
                        printf("FATAL: sigaltstack() doesn't seem to work (sp in signal handler was %08lx, expected %08lx..%08lx)\n", (uint32)sig_sp, (uint32)sig_stack, (uint32)sig_stack + SIG_STACK_SIZE);
                        break;
                case 2:
                        printf("FATAL: r4 in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_r4);
                        break;
                case 3:
                        printf("FATAL: r4 in signal handler doesn't seem to point to a ucontext_t (signal number was %d, expected %d)", sig_sc_signal, SIGUSR2);
                        break;
                case 4:
                        printf("FATAL: sc->regs in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_sc_regs);
                        break;
                case 5:
                        printf("FATAL: sc->regs->gpr[2] in signal handler (%08lx) doesn't have expected value (%08x)\n", (uint32)sig_r2, 0xaffebad5);
                        break;
        }
        if (err) {
                printf("Maybe you need a different kernel?\n");
                exit(1);
        }

        // Clean up
        D(bug("...passed\n"));
        sigaction(SIGUSR2, &old_action, NULL);
        sigaltstack(&old_stack, NULL);
        free(sig_stack);
}


static void sigusr2_handler(int sig, siginfo_t *sip, void *scp)
{
        ucontext_t *ucp = (ucontext_t *)scp;

        // Check whether sigaltstack works
        sig_sp = get_sp();
        if (sig_sp < sig_stack || sig_sp >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
                err = 1;
                return;
        }

        // Check whether r4 points to info on the stack
        sig_r4 = ucp;
        if (sig_r4 < sig_stack || sig_r4 >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
                err = 2;
                return;
        }

        // Check whether context regs points to info on the stack
        sig_sc_regs = &ucp->uc_mcontext->ss.r0;
        if (sig_sc_regs < sig_stack || sig_sc_regs >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
                err = 4;
                return;
        }

        // Check whether r2 still holds the value we set it to
        sig_r2 = ucp->uc_mcontext->ss.r2;
        if (sig_r2 != 0xaffebad5) {
                err = 5;
                return;
        }
}
Revision:	1.2
Committed:	2005-01-30T21:48:20Z (19 years, 9 months ago) by gbeauche
Branch:	MAIN
Changes since 1.1:	+1 -1 lines
Log Message:	Happy New Year 2005!
#	User	Rev	Content
1	gbeauche	1.1	/*
2			* paranoia.cpp - Check undocumented features of the Darwin kernel that
3			* SheepShaver relies upon
4			*
5	gbeauche	1.2	* SheepShaver (C) 1997-2005 Christian Bauer and Marc Hellwig
6	gbeauche	1.1	*
7			* This program is free software; you can redistribute it and/or modify
8			* it under the terms of the GNU General Public License as published by
9			* the Free Software Foundation; either version 2 of the License, or
10			* (at your option) any later version.
11			*
12			* This program is distributed in the hope that it will be useful,
13			* but WITHOUT ANY WARRANTY; without even the implied warranty of
14			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15			* GNU General Public License for more details.
16			*
17			* You should have received a copy of the GNU General Public License
18			* along with this program; if not, write to the Free Software
19			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20			*/
21
22			#include <unistd.h>
23			#include <stdio.h>
24			#include <stdlib.h>
25			#include <string.h>
26			#include <signal.h>
27			#include <errno.h>
28			#include <sys/types.h>
29			#include <sys/ucontext.h>
30
31			#include "sysdeps.h"
32			#include "main.h"
33			#include "user_strings.h"
34
35			#define DEBUG 1
36			#include "debug.h"
37
38
39			// Constants
40			const uint32 SIG_STACK_SIZE = 0x10000; // Size of signal stack
41
42			// Prototypes
43			extern "C" int sigaltstack(const struct sigaltstack ss, struct sigaltstack oss);
44			extern "C" void *get_sp(void);
45			extern "C" void set_r2(uint32 val);
46			extern void paranoia_check(void);
47			static void sigusr2_handler(int sig, siginfo_t sip, void scp);
48
49			// Global variables
50			static void *sig_stack = NULL;
51
52			static int err = 0;
53			static void *sig_sp = NULL;
54			static void *sig_r4 = NULL;
55			static int sig_sc_signal = 0;
56			static void *sig_sc_regs = NULL;
57			static uint32 sig_r2 = 0;
58
59
60			void paranoia_check(void)
61			{
62			char str[256];
63
64			D(bug("Paranoia checks...\n"));
65
66			// Create and install stack for signal handler
67			sig_stack = malloc(SIG_STACK_SIZE);
68			if (sig_stack == NULL) {
69			ErrorAlert(GetString(STR_NOT_ENOUGH_MEMORY_ERR));
70			exit(1);
71			}
72
73			struct sigaltstack old_stack;
74			struct sigaltstack new_stack;
75			new_stack.ss_sp = (char *)sig_stack;
76			new_stack.ss_flags = 0;
77			new_stack.ss_size = SIG_STACK_SIZE;
78			if (sigaltstack(&new_stack, &old_stack) < 0) {
79			sprintf(str, GetString(STR_SIGALTSTACK_ERR), strerror(errno));
80			ErrorAlert(str);
81			exit(1);
82			}
83
84			// Install SIGUSR2 signal handler
85			static struct sigaction old_action;
86			static struct sigaction sigusr2_action;
87			sigemptyset(&sigusr2_action.sa_mask);
88			sigusr2_action.sa_sigaction = sigusr2_handler;
89			sigusr2_action.sa_flags = SA_ONSTACK \| SA_RESTART \| SA_SIGINFO;
90			if (sigaction(SIGUSR2, &sigusr2_action, &old_action) < 0) {
91			sprintf(str, GetString(STR_SIGUSR2_INSTALL_ERR), strerror(errno));
92			ErrorAlert(str);
93			exit(1);
94			}
95
96			// Raise SIGUSR2
97			set_r2(0xaffebad5);
98			raise(SIGUSR2);
99
100			// Check error code
101			switch (err) {
102			case 1:
103			printf("FATAL: sigaltstack() doesn't seem to work (sp in signal handler was %08lx, expected %08lx..%08lx)\n", (uint32)sig_sp, (uint32)sig_stack, (uint32)sig_stack + SIG_STACK_SIZE);
104			break;
105			case 2:
106			printf("FATAL: r4 in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_r4);
107			break;
108			case 3:
109			printf("FATAL: r4 in signal handler doesn't seem to point to a ucontext_t (signal number was %d, expected %d)", sig_sc_signal, SIGUSR2);
110			break;
111			case 4:
112			printf("FATAL: sc->regs in signal handler (%08lx) doesn't point to stack\n", (uint32)sig_sc_regs);
113			break;
114			case 5:
115			printf("FATAL: sc->regs->gpr[2] in signal handler (%08lx) doesn't have expected value (%08x)\n", (uint32)sig_r2, 0xaffebad5);
116			break;
117			}
118			if (err) {
119			printf("Maybe you need a different kernel?\n");
120			exit(1);
121			}
122
123			// Clean up
124			D(bug("...passed\n"));
125			sigaction(SIGUSR2, &old_action, NULL);
126			sigaltstack(&old_stack, NULL);
127			free(sig_stack);
128			}
129
130
131			static void sigusr2_handler(int sig, siginfo_t sip, void scp)
132			{
133			ucontext_t ucp = (ucontext_t )scp;
134
135			// Check whether sigaltstack works
136			sig_sp = get_sp();
137			if (sig_sp < sig_stack \|\| sig_sp >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
138			err = 1;
139			return;
140			}
141
142			// Check whether r4 points to info on the stack
143			sig_r4 = ucp;
144			if (sig_r4 < sig_stack \|\| sig_r4 >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
145			err = 2;
146			return;
147			}
148
149			// Check whether context regs points to info on the stack
150			sig_sc_regs = &ucp->uc_mcontext->ss.r0;
151			if (sig_sc_regs < sig_stack \|\| sig_sc_regs >= ((uint8 *)sig_stack + SIG_STACK_SIZE)) {
152			err = 4;
153			return;
154			}
155
156			// Check whether r2 still holds the value we set it to
157			sig_r2 = ucp->uc_mcontext->ss.r2;
158			if (sig_r2 != 0xaffebad5) {
159			err = 5;
160			return;
161			}
162			}