freebsd-src/usr.bin/proccontrol/proccontrol.c

Ignoring revisions in .git-blame-ignore-revs. Click here to bypass and see the normal blame view.

408 lines
9.7 KiB
C
Raw Normal View History

/*-
* Copyright (c) 2016 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Konstantin Belousov <kib@FreeBSD.org>
* under sponsorship from the FreeBSD Foundation.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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 <sys/cdefs.h>
#include <sys/procctl.h>
#include <err.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
enum {
Implement Address Space Layout Randomization (ASLR) With this change, randomization can be enabled for all non-fixed mappings. It means that the base address for the mapping is selected with a guaranteed amount of entropy (bits). If the mapping was requested to be superpage aligned, the randomization honours the superpage attributes. Although the value of ASLR is diminshing over time as exploit authors work out simple ASLR bypass techniques, it elimintates the trivial exploitation of certain vulnerabilities, at least in theory. This implementation is relatively small and happens at the correct architectural level. Also, it is not expected to introduce regressions in existing cases when turned off (default for now), or cause any significant maintaince burden. The randomization is done on a best-effort basis - that is, the allocator falls back to a first fit strategy if fragmentation prevents entropy injection. It is trivial to implement a strong mode where failure to guarantee the requested amount of entropy results in mapping request failure, but I do not consider that to be usable. I have not fine-tuned the amount of entropy injected right now. It is only a quantitive change that will not change the implementation. The current amount is controlled by aslr_pages_rnd. To not spoil coalescing optimizations, to reduce the page table fragmentation inherent to ASLR, and to keep the transient superpage promotion for the malloced memory, locality clustering is implemented for anonymous private mappings, which are automatically grouped until fragmentation kicks in. The initial location for the anon group range is, of course, randomized. This is controlled by vm.cluster_anon, enabled by default. The default mode keeps the sbrk area unpopulated by other mappings, but this can be turned off, which gives much more breathing bits on architectures with small address space, such as i386. This is tied with the question of following an application's hint about the mmap(2) base address. Testing shows that ignoring the hint does not affect the function of common applications, but I would expect more demanding code could break. By default sbrk is preserved and mmap hints are satisfied, which can be changed by using the kern.elf{32,64}.aslr.honor_sbrk sysctl. ASLR is enabled on per-ABI basis, and currently it is only allowed on FreeBSD native i386 and amd64 (including compat 32bit) ABIs. Support for additional architectures will be added after further testing. Both per-process and per-image controls are implemented: - procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS; - NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible to force ASLR off for the given binary. (A tool to edit the feature control note is in development.) Global controls are: - kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2); - kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings; - kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2); - vm.cluster_anon - enables anon mapping clustering. PR: 208580 (exp runs) Exp-runs done by: antoine Reviewed by: markj (previous version) Discussed with: emaste Tested by: pho MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
MODE_ASLR,
MODE_INVALID,
MODE_TRACE,
MODE_TRAPCAP,
MODE_PROTMAX,
MODE_STACKGAP,
MODE_NO_NEW_PRIVS,
MODE_WXMAP,
#ifdef PROC_KPTI_CTL
MODE_KPTI,
#endif
#ifdef PROC_LA_CTL
MODE_LA57,
MODE_LA48,
#endif
};
static pid_t
str2pid(const char *str)
{
pid_t res;
char *tail;
res = strtol(str, &tail, 0);
if (*tail != '\0') {
warnx("non-numeric pid");
return (-1);
}
return (res);
}
#ifdef PROC_KPTI_CTL
#define KPTI_USAGE "|kpti"
#else
#define KPTI_USAGE
#endif
#ifdef PROC_LA_CTL
#define LA_USAGE "|la48|la57"
#else
#define LA_USAGE
#endif
static void __dead2
usage(void)
{
fprintf(stderr, "Usage: proccontrol -m (aslr|protmax|trace|trapcap|"
"stackgap|nonewprivs|wxmap"KPTI_USAGE LA_USAGE") [-q] "
"[-s (enable|disable)] [-p pid | command]\n");
exit(1);
}
int
main(int argc, char *argv[])
{
int arg, ch, error, mode;
pid_t pid;
bool enable, do_command, query;
mode = MODE_INVALID;
enable = true;
pid = -1;
query = false;
while ((ch = getopt(argc, argv, "m:qs:p:")) != -1) {
switch (ch) {
case 'm':
Implement Address Space Layout Randomization (ASLR) With this change, randomization can be enabled for all non-fixed mappings. It means that the base address for the mapping is selected with a guaranteed amount of entropy (bits). If the mapping was requested to be superpage aligned, the randomization honours the superpage attributes. Although the value of ASLR is diminshing over time as exploit authors work out simple ASLR bypass techniques, it elimintates the trivial exploitation of certain vulnerabilities, at least in theory. This implementation is relatively small and happens at the correct architectural level. Also, it is not expected to introduce regressions in existing cases when turned off (default for now), or cause any significant maintaince burden. The randomization is done on a best-effort basis - that is, the allocator falls back to a first fit strategy if fragmentation prevents entropy injection. It is trivial to implement a strong mode where failure to guarantee the requested amount of entropy results in mapping request failure, but I do not consider that to be usable. I have not fine-tuned the amount of entropy injected right now. It is only a quantitive change that will not change the implementation. The current amount is controlled by aslr_pages_rnd. To not spoil coalescing optimizations, to reduce the page table fragmentation inherent to ASLR, and to keep the transient superpage promotion for the malloced memory, locality clustering is implemented for anonymous private mappings, which are automatically grouped until fragmentation kicks in. The initial location for the anon group range is, of course, randomized. This is controlled by vm.cluster_anon, enabled by default. The default mode keeps the sbrk area unpopulated by other mappings, but this can be turned off, which gives much more breathing bits on architectures with small address space, such as i386. This is tied with the question of following an application's hint about the mmap(2) base address. Testing shows that ignoring the hint does not affect the function of common applications, but I would expect more demanding code could break. By default sbrk is preserved and mmap hints are satisfied, which can be changed by using the kern.elf{32,64}.aslr.honor_sbrk sysctl. ASLR is enabled on per-ABI basis, and currently it is only allowed on FreeBSD native i386 and amd64 (including compat 32bit) ABIs. Support for additional architectures will be added after further testing. Both per-process and per-image controls are implemented: - procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS; - NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible to force ASLR off for the given binary. (A tool to edit the feature control note is in development.) Global controls are: - kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2); - kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings; - kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2); - vm.cluster_anon - enables anon mapping clustering. PR: 208580 (exp runs) Exp-runs done by: antoine Reviewed by: markj (previous version) Discussed with: emaste Tested by: pho MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
if (strcmp(optarg, "aslr") == 0)
mode = MODE_ASLR;
else if (strcmp(optarg, "protmax") == 0)
mode = MODE_PROTMAX;
Implement Address Space Layout Randomization (ASLR) With this change, randomization can be enabled for all non-fixed mappings. It means that the base address for the mapping is selected with a guaranteed amount of entropy (bits). If the mapping was requested to be superpage aligned, the randomization honours the superpage attributes. Although the value of ASLR is diminshing over time as exploit authors work out simple ASLR bypass techniques, it elimintates the trivial exploitation of certain vulnerabilities, at least in theory. This implementation is relatively small and happens at the correct architectural level. Also, it is not expected to introduce regressions in existing cases when turned off (default for now), or cause any significant maintaince burden. The randomization is done on a best-effort basis - that is, the allocator falls back to a first fit strategy if fragmentation prevents entropy injection. It is trivial to implement a strong mode where failure to guarantee the requested amount of entropy results in mapping request failure, but I do not consider that to be usable. I have not fine-tuned the amount of entropy injected right now. It is only a quantitive change that will not change the implementation. The current amount is controlled by aslr_pages_rnd. To not spoil coalescing optimizations, to reduce the page table fragmentation inherent to ASLR, and to keep the transient superpage promotion for the malloced memory, locality clustering is implemented for anonymous private mappings, which are automatically grouped until fragmentation kicks in. The initial location for the anon group range is, of course, randomized. This is controlled by vm.cluster_anon, enabled by default. The default mode keeps the sbrk area unpopulated by other mappings, but this can be turned off, which gives much more breathing bits on architectures with small address space, such as i386. This is tied with the question of following an application's hint about the mmap(2) base address. Testing shows that ignoring the hint does not affect the function of common applications, but I would expect more demanding code could break. By default sbrk is preserved and mmap hints are satisfied, which can be changed by using the kern.elf{32,64}.aslr.honor_sbrk sysctl. ASLR is enabled on per-ABI basis, and currently it is only allowed on FreeBSD native i386 and amd64 (including compat 32bit) ABIs. Support for additional architectures will be added after further testing. Both per-process and per-image controls are implemented: - procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS; - NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible to force ASLR off for the given binary. (A tool to edit the feature control note is in development.) Global controls are: - kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2); - kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings; - kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2); - vm.cluster_anon - enables anon mapping clustering. PR: 208580 (exp runs) Exp-runs done by: antoine Reviewed by: markj (previous version) Discussed with: emaste Tested by: pho MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
else if (strcmp(optarg, "trace") == 0)
mode = MODE_TRACE;
else if (strcmp(optarg, "trapcap") == 0)
mode = MODE_TRAPCAP;
else if (strcmp(optarg, "stackgap") == 0)
mode = MODE_STACKGAP;
else if (strcmp(optarg, "nonewprivs") == 0)
mode = MODE_NO_NEW_PRIVS;
else if (strcmp(optarg, "wxmap") == 0)
mode = MODE_WXMAP;
#ifdef PROC_KPTI_CTL
else if (strcmp(optarg, "kpti") == 0)
mode = MODE_KPTI;
#endif
#ifdef PROC_LA_CTL
else if (strcmp(optarg, "la57") == 0)
mode = MODE_LA57;
else if (strcmp(optarg, "la48") == 0)
mode = MODE_LA48;
#endif
else
usage();
break;
case 's':
if (strcmp(optarg, "enable") == 0)
enable = true;
else if (strcmp(optarg, "disable") == 0)
enable = false;
else
usage();
break;
case 'p':
pid = str2pid(optarg);
break;
case 'q':
query = true;
break;
case '?':
default:
usage();
break;
}
}
argc -= optind;
argv += optind;
do_command = argc != 0;
if (do_command) {
if (pid != -1 || query)
usage();
pid = getpid();
} else if (pid == -1) {
pid = getpid();
}
if (query) {
switch (mode) {
Implement Address Space Layout Randomization (ASLR) With this change, randomization can be enabled for all non-fixed mappings. It means that the base address for the mapping is selected with a guaranteed amount of entropy (bits). If the mapping was requested to be superpage aligned, the randomization honours the superpage attributes. Although the value of ASLR is diminshing over time as exploit authors work out simple ASLR bypass techniques, it elimintates the trivial exploitation of certain vulnerabilities, at least in theory. This implementation is relatively small and happens at the correct architectural level. Also, it is not expected to introduce regressions in existing cases when turned off (default for now), or cause any significant maintaince burden. The randomization is done on a best-effort basis - that is, the allocator falls back to a first fit strategy if fragmentation prevents entropy injection. It is trivial to implement a strong mode where failure to guarantee the requested amount of entropy results in mapping request failure, but I do not consider that to be usable. I have not fine-tuned the amount of entropy injected right now. It is only a quantitive change that will not change the implementation. The current amount is controlled by aslr_pages_rnd. To not spoil coalescing optimizations, to reduce the page table fragmentation inherent to ASLR, and to keep the transient superpage promotion for the malloced memory, locality clustering is implemented for anonymous private mappings, which are automatically grouped until fragmentation kicks in. The initial location for the anon group range is, of course, randomized. This is controlled by vm.cluster_anon, enabled by default. The default mode keeps the sbrk area unpopulated by other mappings, but this can be turned off, which gives much more breathing bits on architectures with small address space, such as i386. This is tied with the question of following an application's hint about the mmap(2) base address. Testing shows that ignoring the hint does not affect the function of common applications, but I would expect more demanding code could break. By default sbrk is preserved and mmap hints are satisfied, which can be changed by using the kern.elf{32,64}.aslr.honor_sbrk sysctl. ASLR is enabled on per-ABI basis, and currently it is only allowed on FreeBSD native i386 and amd64 (including compat 32bit) ABIs. Support for additional architectures will be added after further testing. Both per-process and per-image controls are implemented: - procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS; - NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible to force ASLR off for the given binary. (A tool to edit the feature control note is in development.) Global controls are: - kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2); - kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings; - kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2); - vm.cluster_anon - enables anon mapping clustering. PR: 208580 (exp runs) Exp-runs done by: antoine Reviewed by: markj (previous version) Discussed with: emaste Tested by: pho MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
case MODE_ASLR:
error = procctl(P_PID, pid, PROC_ASLR_STATUS, &arg);
break;
case MODE_TRACE:
error = procctl(P_PID, pid, PROC_TRACE_STATUS, &arg);
break;
case MODE_TRAPCAP:
error = procctl(P_PID, pid, PROC_TRAPCAP_STATUS, &arg);
break;
case MODE_PROTMAX:
error = procctl(P_PID, pid, PROC_PROTMAX_STATUS, &arg);
break;
case MODE_STACKGAP:
error = procctl(P_PID, pid, PROC_STACKGAP_STATUS, &arg);
break;
case MODE_NO_NEW_PRIVS:
error = procctl(P_PID, pid, PROC_NO_NEW_PRIVS_STATUS,
&arg);
break;
case MODE_WXMAP:
error = procctl(P_PID, pid, PROC_WXMAP_STATUS, &arg);
break;
#ifdef PROC_KPTI_CTL
case MODE_KPTI:
error = procctl(P_PID, pid, PROC_KPTI_STATUS, &arg);
break;
#endif
#ifdef PROC_LA_CTL
case MODE_LA57:
case MODE_LA48:
error = procctl(P_PID, pid, PROC_LA_STATUS, &arg);
break;
#endif
default:
usage();
break;
}
if (error != 0)
err(1, "procctl status");
switch (mode) {
Implement Address Space Layout Randomization (ASLR) With this change, randomization can be enabled for all non-fixed mappings. It means that the base address for the mapping is selected with a guaranteed amount of entropy (bits). If the mapping was requested to be superpage aligned, the randomization honours the superpage attributes. Although the value of ASLR is diminshing over time as exploit authors work out simple ASLR bypass techniques, it elimintates the trivial exploitation of certain vulnerabilities, at least in theory. This implementation is relatively small and happens at the correct architectural level. Also, it is not expected to introduce regressions in existing cases when turned off (default for now), or cause any significant maintaince burden. The randomization is done on a best-effort basis - that is, the allocator falls back to a first fit strategy if fragmentation prevents entropy injection. It is trivial to implement a strong mode where failure to guarantee the requested amount of entropy results in mapping request failure, but I do not consider that to be usable. I have not fine-tuned the amount of entropy injected right now. It is only a quantitive change that will not change the implementation. The current amount is controlled by aslr_pages_rnd. To not spoil coalescing optimizations, to reduce the page table fragmentation inherent to ASLR, and to keep the transient superpage promotion for the malloced memory, locality clustering is implemented for anonymous private mappings, which are automatically grouped until fragmentation kicks in. The initial location for the anon group range is, of course, randomized. This is controlled by vm.cluster_anon, enabled by default. The default mode keeps the sbrk area unpopulated by other mappings, but this can be turned off, which gives much more breathing bits on architectures with small address space, such as i386. This is tied with the question of following an application's hint about the mmap(2) base address. Testing shows that ignoring the hint does not affect the function of common applications, but I would expect more demanding code could break. By default sbrk is preserved and mmap hints are satisfied, which can be changed by using the kern.elf{32,64}.aslr.honor_sbrk sysctl. ASLR is enabled on per-ABI basis, and currently it is only allowed on FreeBSD native i386 and amd64 (including compat 32bit) ABIs. Support for additional architectures will be added after further testing. Both per-process and per-image controls are implemented: - procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS; - NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible to force ASLR off for the given binary. (A tool to edit the feature control note is in development.) Global controls are: - kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2); - kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings; - kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2); - vm.cluster_anon - enables anon mapping clustering. PR: 208580 (exp runs) Exp-runs done by: antoine Reviewed by: markj (previous version) Discussed with: emaste Tested by: pho MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
case MODE_ASLR:
switch (arg & ~PROC_ASLR_ACTIVE) {
case PROC_ASLR_FORCE_ENABLE:
printf("force enabled");
break;
case PROC_ASLR_FORCE_DISABLE:
printf("force disabled");
break;
case PROC_ASLR_NOFORCE:
printf("not forced");
break;
}
if ((arg & PROC_ASLR_ACTIVE) != 0)
printf(", active\n");
else
printf(", not active\n");
break;
case MODE_TRACE:
if (arg == -1)
printf("disabled\n");
else if (arg == 0)
printf("enabled, no debugger\n");
else
printf("enabled, traced by %d\n", arg);
break;
case MODE_TRAPCAP:
switch (arg) {
case PROC_TRAPCAP_CTL_ENABLE:
printf("enabled\n");
break;
case PROC_TRAPCAP_CTL_DISABLE:
printf("disabled\n");
break;
}
break;
case MODE_PROTMAX:
switch (arg & ~PROC_PROTMAX_ACTIVE) {
case PROC_PROTMAX_FORCE_ENABLE:
printf("force enabled");
break;
case PROC_PROTMAX_FORCE_DISABLE:
printf("force disabled");
break;
case PROC_PROTMAX_NOFORCE:
printf("not forced");
break;
}
if ((arg & PROC_PROTMAX_ACTIVE) != 0)
printf(", active\n");
else
printf(", not active\n");
break;
case MODE_STACKGAP:
switch (arg & (PROC_STACKGAP_ENABLE |
PROC_STACKGAP_DISABLE)) {
case PROC_STACKGAP_ENABLE:
printf("enabled\n");
break;
case PROC_STACKGAP_DISABLE:
printf("disabled\n");
break;
}
switch (arg & (PROC_STACKGAP_ENABLE_EXEC |
PROC_STACKGAP_DISABLE_EXEC)) {
case PROC_STACKGAP_ENABLE_EXEC:
printf("enabled after exec\n");
break;
case PROC_STACKGAP_DISABLE_EXEC:
printf("disabled after exec\n");
break;
}
break;
case MODE_NO_NEW_PRIVS:
switch (arg) {
case PROC_NO_NEW_PRIVS_ENABLE:
printf("enabled\n");
break;
case PROC_NO_NEW_PRIVS_DISABLE:
printf("disabled\n");
break;
}
break;
case MODE_WXMAP:
if ((arg & PROC_WX_MAPPINGS_PERMIT) != 0)
printf("enabled");
else
printf("disabled");
if ((arg & PROC_WX_MAPPINGS_DISALLOW_EXEC) != 0)
printf(", disabled on exec");
if ((arg & PROC_WXORX_ENFORCE) != 0)
printf(", wxorx enforced");
printf("\n");
break;
#ifdef PROC_KPTI_CTL
case MODE_KPTI:
switch (arg & ~PROC_KPTI_STATUS_ACTIVE) {
case PROC_KPTI_CTL_ENABLE_ON_EXEC:
printf("enabled");
break;
case PROC_KPTI_CTL_DISABLE_ON_EXEC:
printf("disabled");
break;
}
if ((arg & PROC_KPTI_STATUS_ACTIVE) != 0)
printf(", active\n");
else
printf(", not active\n");
break;
#endif
#ifdef PROC_LA_CTL
case MODE_LA57:
case MODE_LA48:
switch (arg & ~(PROC_LA_STATUS_LA48 |
PROC_LA_STATUS_LA57)) {
case PROC_LA_CTL_LA48_ON_EXEC:
printf("la48 on exec");
break;
case PROC_LA_CTL_LA57_ON_EXEC:
printf("la57 on exec");
break;
case PROC_LA_CTL_DEFAULT_ON_EXEC:
printf("default on exec");
break;
}
if ((arg & PROC_LA_STATUS_LA48) != 0)
printf(", la48 active\n");
else if ((arg & PROC_LA_STATUS_LA57) != 0)
printf(", la57 active\n");
break;
#endif
}
} else {
switch (mode) {
Implement Address Space Layout Randomization (ASLR) With this change, randomization can be enabled for all non-fixed mappings. It means that the base address for the mapping is selected with a guaranteed amount of entropy (bits). If the mapping was requested to be superpage aligned, the randomization honours the superpage attributes. Although the value of ASLR is diminshing over time as exploit authors work out simple ASLR bypass techniques, it elimintates the trivial exploitation of certain vulnerabilities, at least in theory. This implementation is relatively small and happens at the correct architectural level. Also, it is not expected to introduce regressions in existing cases when turned off (default for now), or cause any significant maintaince burden. The randomization is done on a best-effort basis - that is, the allocator falls back to a first fit strategy if fragmentation prevents entropy injection. It is trivial to implement a strong mode where failure to guarantee the requested amount of entropy results in mapping request failure, but I do not consider that to be usable. I have not fine-tuned the amount of entropy injected right now. It is only a quantitive change that will not change the implementation. The current amount is controlled by aslr_pages_rnd. To not spoil coalescing optimizations, to reduce the page table fragmentation inherent to ASLR, and to keep the transient superpage promotion for the malloced memory, locality clustering is implemented for anonymous private mappings, which are automatically grouped until fragmentation kicks in. The initial location for the anon group range is, of course, randomized. This is controlled by vm.cluster_anon, enabled by default. The default mode keeps the sbrk area unpopulated by other mappings, but this can be turned off, which gives much more breathing bits on architectures with small address space, such as i386. This is tied with the question of following an application's hint about the mmap(2) base address. Testing shows that ignoring the hint does not affect the function of common applications, but I would expect more demanding code could break. By default sbrk is preserved and mmap hints are satisfied, which can be changed by using the kern.elf{32,64}.aslr.honor_sbrk sysctl. ASLR is enabled on per-ABI basis, and currently it is only allowed on FreeBSD native i386 and amd64 (including compat 32bit) ABIs. Support for additional architectures will be added after further testing. Both per-process and per-image controls are implemented: - procctl(2) adds PROC_ASLR_CTL/PROC_ASLR_STATUS; - NT_FREEBSD_FCTL_ASLR_DISABLE feature control note bit makes it possible to force ASLR off for the given binary. (A tool to edit the feature control note is in development.) Global controls are: - kern.elf{32,64}.aslr.enable - for non-fixed mappings done by mmap(2); - kern.elf{32,64}.aslr.pie_enable - for PIE image activation mappings; - kern.elf{32,64}.aslr.honor_sbrk - allow to use sbrk area for mmap(2); - vm.cluster_anon - enables anon mapping clustering. PR: 208580 (exp runs) Exp-runs done by: antoine Reviewed by: markj (previous version) Discussed with: emaste Tested by: pho MFC after: 1 month Sponsored by: The FreeBSD Foundation Differential revision: https://reviews.freebsd.org/D5603
2019-02-10 17:19:45 +00:00
case MODE_ASLR:
arg = enable ? PROC_ASLR_FORCE_ENABLE :
PROC_ASLR_FORCE_DISABLE;
error = procctl(P_PID, pid, PROC_ASLR_CTL, &arg);
break;
case MODE_TRACE:
arg = enable ? PROC_TRACE_CTL_ENABLE :
PROC_TRACE_CTL_DISABLE;
error = procctl(P_PID, pid, PROC_TRACE_CTL, &arg);
break;
case MODE_TRAPCAP:
arg = enable ? PROC_TRAPCAP_CTL_ENABLE :
PROC_TRAPCAP_CTL_DISABLE;
error = procctl(P_PID, pid, PROC_TRAPCAP_CTL, &arg);
break;
case MODE_PROTMAX:
arg = enable ? PROC_PROTMAX_FORCE_ENABLE :
PROC_PROTMAX_FORCE_DISABLE;
error = procctl(P_PID, pid, PROC_PROTMAX_CTL, &arg);
break;
case MODE_STACKGAP:
arg = enable ? PROC_STACKGAP_ENABLE_EXEC :
(PROC_STACKGAP_DISABLE |
PROC_STACKGAP_DISABLE_EXEC);
error = procctl(P_PID, pid, PROC_STACKGAP_CTL, &arg);
break;
case MODE_NO_NEW_PRIVS:
arg = enable ? PROC_NO_NEW_PRIVS_ENABLE :
PROC_NO_NEW_PRIVS_DISABLE;
error = procctl(P_PID, pid, PROC_NO_NEW_PRIVS_CTL,
&arg);
break;
case MODE_WXMAP:
arg = enable ? PROC_WX_MAPPINGS_PERMIT :
PROC_WX_MAPPINGS_DISALLOW_EXEC;
error = procctl(P_PID, pid, PROC_WXMAP_CTL, &arg);
break;
#ifdef PROC_KPTI_CTL
case MODE_KPTI:
arg = enable ? PROC_KPTI_CTL_ENABLE_ON_EXEC :
PROC_KPTI_CTL_DISABLE_ON_EXEC;
error = procctl(P_PID, pid, PROC_KPTI_CTL, &arg);
break;
#endif
#ifdef PROC_LA_CTL
case MODE_LA57:
arg = enable ? PROC_LA_CTL_LA57_ON_EXEC :
PROC_LA_CTL_DEFAULT_ON_EXEC;
error = procctl(P_PID, pid, PROC_LA_CTL, &arg);
break;
case MODE_LA48:
arg = enable ? PROC_LA_CTL_LA48_ON_EXEC :
PROC_LA_CTL_DEFAULT_ON_EXEC;
error = procctl(P_PID, pid, PROC_LA_CTL, &arg);
break;
#endif
default:
usage();
break;
}
if (error != 0)
err(1, "procctl ctl");
if (do_command) {
error = execvp(argv[0], argv);
err(1, "exec");
}
}
exit(0);
}