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linux/tools/testing/selftests/user_events/ftrace_test.c
Beau Belgrave 97bbce89bf tracing/user_events: Prevent same address and bit per process 
User processes register an address and bit pair for events. If the same
address and bit pair are registered multiple times in the same process,
it can cause undefined behavior when events are enabled/disabled.
When more than one are used, the bit could be turned off by another
event being disabled, while the original event is still enabled.

Prevent undefined behavior by checking the current mm to see if any
event has already been registered for the address and bit pair. Return
EADDRINUSE back to the user process if it's already being used.

Update ftrace self-test to ensure this occurs properly.

Link: https://lkml.kernel.org/r/20230425225107.8525-4-beaub@linux.microsoft.com

Suggested-by: Doug Cook <dcook@linux.microsoft.com>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-04-25 21:04:32 -04:00

510 lines
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// SPDX-License-Identifier: GPL-2.0
/*
* User Events FTrace Test Program
*
* Copyright (c) 2021 Beau Belgrave <beaub@linux.microsoft.com>
*/
#include <errno.h>
#include <linux/user_events.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <unistd.h>
#include "../kselftest_harness.h"
const char *data_file = "/sys/kernel/tracing/user_events_data";
const char *status_file = "/sys/kernel/tracing/user_events_status";
const char *enable_file = "/sys/kernel/tracing/events/user_events/__test_event/enable";
const char *trace_file = "/sys/kernel/tracing/trace";
const char *fmt_file = "/sys/kernel/tracing/events/user_events/__test_event/format";
static int trace_bytes(void)
{
int fd = open(trace_file, O_RDONLY);
char buf[256];
int bytes = 0, got;
if (fd == -1)
return -1;
while (true) {
got = read(fd, buf, sizeof(buf));
if (got == -1)
return -1;
if (got == 0)
break;
bytes += got;
}
close(fd);
return bytes;
}
static int skip_until_empty_line(FILE *fp)
{
int c, last = 0;
while (true) {
c = getc(fp);
if (c == EOF)
break;
if (last == '\n' && c == '\n')
return 0;
last = c;
}
return -1;
}
static int get_print_fmt(char *buffer, int len)
{
FILE *fp = fopen(fmt_file, "r");
char *newline;
if (!fp)
return -1;
/* Read until empty line (Skip Common) */
if (skip_until_empty_line(fp) < 0)
goto err;
/* Read until empty line (Skip Properties) */
if (skip_until_empty_line(fp) < 0)
goto err;
/* Read in print_fmt: */
if (fgets(buffer, len, fp) == NULL)
goto err;
newline = strchr(buffer, '\n');
if (newline)
*newline = '\0';
fclose(fp);
return 0;
err:
fclose(fp);
return -1;
}
static int clear(int *check)
{
struct user_unreg unreg = {0};
unreg.size = sizeof(unreg);
unreg.disable_bit = 31;
unreg.disable_addr = (__u64)check;
int fd = open(data_file, O_RDWR);
if (fd == -1)
return -1;
if (ioctl(fd, DIAG_IOCSUNREG, &unreg) == -1)
if (errno != ENOENT)
return -1;
if (ioctl(fd, DIAG_IOCSDEL, "__test_event") == -1)
if (errno != ENOENT)
return -1;
close(fd);
return 0;
}
static int check_print_fmt(const char *event, const char *expected, int *check)
{
struct user_reg reg = {0};
char print_fmt[256];
int ret;
int fd;
/* Ensure cleared */
ret = clear(check);
if (ret != 0)
return ret;
fd = open(data_file, O_RDWR);
if (fd == -1)
return fd;
reg.size = sizeof(reg);
reg.name_args = (__u64)event;
reg.enable_bit = 31;
reg.enable_addr = (__u64)check;
reg.enable_size = sizeof(*check);
/* Register should work */
ret = ioctl(fd, DIAG_IOCSREG, &reg);
close(fd);
if (ret != 0) {
printf("Reg failed in fmt\n");
return ret;
}
/* Ensure correct print_fmt */
ret = get_print_fmt(print_fmt, sizeof(print_fmt));
if (ret != 0)
return ret;
return strcmp(print_fmt, expected);
}
FIXTURE(user) {
int status_fd;
int data_fd;
int enable_fd;
int check;
};
FIXTURE_SETUP(user) {
self->status_fd = open(status_file, O_RDONLY);
ASSERT_NE(-1, self->status_fd);
self->data_fd = open(data_file, O_RDWR);
ASSERT_NE(-1, self->data_fd);
self->enable_fd = -1;
}
FIXTURE_TEARDOWN(user) {
close(self->status_fd);
close(self->data_fd);
if (self->enable_fd != -1) {
write(self->enable_fd, "0", sizeof("0"));
close(self->enable_fd);
}
if (clear(&self->check) != 0)
printf("WARNING: Clear didn't work!\n");
}
TEST_F(user, register_events) {
struct user_reg reg = {0};
struct user_unreg unreg = {0};
reg.size = sizeof(reg);
reg.name_args = (__u64)"__test_event u32 field1; u32 field2";
reg.enable_bit = 31;
reg.enable_addr = (__u64)&self->check;
reg.enable_size = sizeof(self->check);
unreg.size = sizeof(unreg);
unreg.disable_bit = 31;
unreg.disable_addr = (__u64)&self->check;
/* Register should work */
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
/* Multiple registers to the same addr + bit should fail */
ASSERT_EQ(-1, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(EADDRINUSE, errno);
/* Multiple registers to same name should result in same index */
reg.enable_bit = 30;
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
/* Ensure disabled */
self->enable_fd = open(enable_file, O_RDWR);
ASSERT_NE(-1, self->enable_fd);
ASSERT_NE(-1, write(self->enable_fd, "0", sizeof("0")))
/* Enable event and ensure bits updated in status */
ASSERT_NE(-1, write(self->enable_fd, "1", sizeof("1")))
ASSERT_EQ(1 << reg.enable_bit, self->check);
/* Disable event and ensure bits updated in status */
ASSERT_NE(-1, write(self->enable_fd, "0", sizeof("0")))
ASSERT_EQ(0, self->check);
/* File still open should return -EBUSY for delete */
ASSERT_EQ(-1, ioctl(self->data_fd, DIAG_IOCSDEL, "__test_event"));
ASSERT_EQ(EBUSY, errno);
/* Unregister */
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSUNREG, &unreg));
unreg.disable_bit = 30;
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSUNREG, &unreg));
/* Delete should work only after close and unregister */
close(self->data_fd);
self->data_fd = open(data_file, O_RDWR);
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSDEL, "__test_event"));
}
TEST_F(user, write_events) {
struct user_reg reg = {0};
struct iovec io[3];
__u32 field1, field2;
int before = 0, after = 0;
reg.size = sizeof(reg);
reg.name_args = (__u64)"__test_event u32 field1; u32 field2";
reg.enable_bit = 31;
reg.enable_addr = (__u64)&self->check;
reg.enable_size = sizeof(self->check);
field1 = 1;
field2 = 2;
io[0].iov_base = &reg.write_index;
io[0].iov_len = sizeof(reg.write_index);
io[1].iov_base = &field1;
io[1].iov_len = sizeof(field1);
io[2].iov_base = &field2;
io[2].iov_len = sizeof(field2);
/* Register should work */
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
ASSERT_EQ(0, self->check);
/* Write should fail on invalid slot with ENOENT */
io[0].iov_base = &field2;
io[0].iov_len = sizeof(field2);
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(ENOENT, errno);
io[0].iov_base = &reg.write_index;
io[0].iov_len = sizeof(reg.write_index);
/* Enable event */
self->enable_fd = open(enable_file, O_RDWR);
ASSERT_NE(-1, write(self->enable_fd, "1", sizeof("1")))
/* Event should now be enabled */
ASSERT_NE(1 << reg.enable_bit, self->check);
/* Write should make it out to ftrace buffers */
before = trace_bytes();
ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 3));
after = trace_bytes();
ASSERT_GT(after, before);
/* Negative index should fail with EINVAL */
reg.write_index = -1;
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(EINVAL, errno);
}
TEST_F(user, write_fault) {
struct user_reg reg = {0};
struct iovec io[2];
int l = sizeof(__u64);
void *anon;
reg.size = sizeof(reg);
reg.name_args = (__u64)"__test_event u64 anon";
reg.enable_bit = 31;
reg.enable_addr = (__u64)&self->check;
reg.enable_size = sizeof(self->check);
anon = mmap(NULL, l, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
ASSERT_NE(MAP_FAILED, anon);
io[0].iov_base = &reg.write_index;
io[0].iov_len = sizeof(reg.write_index);
io[1].iov_base = anon;
io[1].iov_len = l;
/* Register should work */
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
/* Write should work normally */
ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 2));
/* Faulted data should zero fill and work */
ASSERT_EQ(0, madvise(anon, l, MADV_DONTNEED));
ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 2));
ASSERT_EQ(0, munmap(anon, l));
}
TEST_F(user, write_validator) {
struct user_reg reg = {0};
struct iovec io[3];
int loc, bytes;
char data[8];
int before = 0, after = 0;
reg.size = sizeof(reg);
reg.name_args = (__u64)"__test_event __rel_loc char[] data";
reg.enable_bit = 31;
reg.enable_addr = (__u64)&self->check;
reg.enable_size = sizeof(self->check);
/* Register should work */
ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, &reg));
ASSERT_EQ(0, reg.write_index);
ASSERT_EQ(0, self->check);
io[0].iov_base = &reg.write_index;
io[0].iov_len = sizeof(reg.write_index);
io[1].iov_base = &loc;
io[1].iov_len = sizeof(loc);
io[2].iov_base = data;
bytes = snprintf(data, sizeof(data), "Test") + 1;
io[2].iov_len = bytes;
/* Undersized write should fail */
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 1));
ASSERT_EQ(EINVAL, errno);
/* Enable event */
self->enable_fd = open(enable_file, O_RDWR);
ASSERT_NE(-1, write(self->enable_fd, "1", sizeof("1")))
/* Event should now be enabled */
ASSERT_EQ(1 << reg.enable_bit, self->check);
/* Full in-bounds write should work */
before = trace_bytes();
loc = DYN_LOC(0, bytes);
ASSERT_NE(-1, writev(self->data_fd, (const struct iovec *)io, 3));
after = trace_bytes();
ASSERT_GT(after, before);
/* Out of bounds write should fault (offset way out) */
loc = DYN_LOC(1024, bytes);
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(EFAULT, errno);
/* Out of bounds write should fault (offset 1 byte out) */
loc = DYN_LOC(1, bytes);
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(EFAULT, errno);
/* Out of bounds write should fault (size way out) */
loc = DYN_LOC(0, bytes + 1024);
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(EFAULT, errno);
/* Out of bounds write should fault (size 1 byte out) */
loc = DYN_LOC(0, bytes + 1);
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(EFAULT, errno);
/* Non-Null should fault */
memset(data, 'A', sizeof(data));
loc = DYN_LOC(0, bytes);
ASSERT_EQ(-1, writev(self->data_fd, (const struct iovec *)io, 3));
ASSERT_EQ(EFAULT, errno);
}
TEST_F(user, print_fmt) {
int ret;
ret = check_print_fmt("__test_event __rel_loc char[] data",
"print fmt: \"data=%s\", __get_rel_str(data)",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event __data_loc char[] data",
"print fmt: \"data=%s\", __get_str(data)",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event s64 data",
"print fmt: \"data=%lld\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event u64 data",
"print fmt: \"data=%llu\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event s32 data",
"print fmt: \"data=%d\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event u32 data",
"print fmt: \"data=%u\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event int data",
"print fmt: \"data=%d\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event unsigned int data",
"print fmt: \"data=%u\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event s16 data",
"print fmt: \"data=%d\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event u16 data",
"print fmt: \"data=%u\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event short data",
"print fmt: \"data=%d\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event unsigned short data",
"print fmt: \"data=%u\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event s8 data",
"print fmt: \"data=%d\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event u8 data",
"print fmt: \"data=%u\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event char data",
"print fmt: \"data=%d\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event unsigned char data",
"print fmt: \"data=%u\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
ret = check_print_fmt("__test_event char[4] data",
"print fmt: \"data=%s\", REC->data",
&self->check);
ASSERT_EQ(0, ret);
}
int main(int argc, char **argv)
{
return test_harness_run(argc, argv);
}
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