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passt/util.h
David Gibson 1daf6f4615 conf, fwd: Make ephemeral port logic more flexible 
"Ephemeral" ports are those which the kernel may allocate as local
port numbers for outgoing connections or datagrams.  Because of that,
they're generally not good choices for listening servers to bind to.

Thefore when using -t all, -u all or exclude-only ranges, we map only
non-ephemeral ports.  Our logic for this is a bit rigid though: we
assume the ephemeral ports are always a fixed range at the top of the
port number space.  We also assume PORT_EPHEMERAL_MIN is a multiple of
8, or we won't set the forward bitmap correctly.

Make the logic in conf.c more flexible, using a helper moved into
fwd.[ch], although we don't change which ports we consider ephemeral
(yet).

The new handling is undoubtedly more computationally expensive, but
since it's a once-off operation at start off, I don't think it really
matters.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2024-08-29 22:25:51 +02:00

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/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright (c) 2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#ifndef UTIL_H
#define UTIL_H
#include <stdlib.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <signal.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <linux/close_range.h>
#include "log.h"
#define VERSION_BLOB \
VERSION "\n" \
"Copyright Red Hat\n" \
"GNU General Public License, version 2 or later\n" \
" <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>\n" \
"This is free software: you are free to change and redistribute it.\n" \
"There is NO WARRANTY, to the extent permitted by law.\n\n"
#ifndef SECCOMP_RET_KILL_PROCESS
#define SECCOMP_RET_KILL_PROCESS SECCOMP_RET_KILL
#endif
#ifndef ETH_MAX_MTU
#define ETH_MAX_MTU USHRT_MAX
#endif
#ifndef ETH_MIN_MTU
#define ETH_MIN_MTU 68
#endif
#ifndef IP_MAX_MTU
#define IP_MAX_MTU USHRT_MAX
#endif
#ifndef MIN
#define MIN(x, y) (((x) < (y)) ? (x) : (y))
#endif
#ifndef MAX
#define MAX(x, y) (((x) > (y)) ? (x) : (y))
#endif
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
#define DIV_ROUND_CLOSEST(n, d) (((n) + (d) / 2) / (d))
#define ROUND_DOWN(x, y) ((x) & ~((y) - 1))
#define ROUND_UP(x, y) (((x) + (y) - 1) & ~((y) - 1))
#define MAX_FROM_BITS(n) (((1U << (n)) - 1))
#define BIT(n) (1UL << (n))
#define BITMAP_BIT(n) (BIT((n) % (sizeof(long) * 8)))
#define BITMAP_WORD(n) (n / (sizeof(long) * 8))
#define SWAP(a, b) \
do { \
__typeof__(a) __x = (a); (a) = (b); (b) = __x; \
} while (0) \
#define STRINGIFY(x) #x
#define STR(x) STRINGIFY(x)
#define ASSERT(expr) \
do { \
if (!(expr)) { \
err("ASSERTION FAILED in %s (%s:%d): %s", \
__func__, __FILE__, __LINE__, STRINGIFY(expr)); \
/* This may actually SIGSYS, due to seccomp, \
* but that will still get the job done \
*/ \
abort(); \
} \
} while (0)
#ifdef P_tmpdir
#define TMPDIR P_tmpdir
#else
#define TMPDIR "/tmp"
#endif
#define V4 0
#define V6 1
#define IP_VERSIONS 2
#define ARRAY_SIZE(a) ((int)(sizeof(a) / sizeof((a)[0])))
#define IN_INTERVAL(a, b, x) ((x) >= (a) && (x) <= (b))
#define FD_PROTO(x, proto) \
(IN_INTERVAL(c->proto.fd_min, c->proto.fd_max, (x)))
#define MAC_ZERO ((uint8_t [ETH_ALEN]){ 0 })
#define MAC_IS_ZERO(addr) (!memcmp((addr), MAC_ZERO, ETH_ALEN))
#ifndef __bswap_constant_16
#define __bswap_constant_16(x) \
((uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
#endif
#ifndef __bswap_constant_32
#define __bswap_constant_32(x) \
((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >> 8) | \
(((x) & 0x0000ff00) << 8) | (((x) & 0x000000ff) << 24))
#endif
#if __BYTE_ORDER == __BIG_ENDIAN
#define htons_constant(x) (x)
#define htonl_constant(x) (x)
#else
#define htons_constant(x) (__bswap_constant_16(x))
#define htonl_constant(x) (__bswap_constant_32(x))
#endif
/**
* ntohl_unaligned() - Read 32-bit BE value from a possibly unaligned address
* @p: Pointer to the BE value in memory
*
* Returns: Host-order value of 32-bit BE quantity at @p
*/
static inline uint32_t ntohl_unaligned(const void *p)
{
uint32_t val;
memcpy(&val, p, sizeof(val));
return ntohl(val);
}
#define NS_FN_STACK_SIZE (RLIMIT_STACK_VAL * 1024 / 8)
int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
void *arg);
#define NS_CALL(fn, arg) \
do { \
char ns_fn_stack[NS_FN_STACK_SIZE] \
__attribute__ ((aligned(__alignof__(max_align_t)))); \
\
do_clone((fn), ns_fn_stack, sizeof(ns_fn_stack), \
CLONE_VM | CLONE_VFORK | CLONE_FILES | SIGCHLD,\
(void *)(arg)); \
} while (0)
#define RCVBUF_BIG (2UL * 1024 * 1024)
#define SNDBUF_BIG (4UL * 1024 * 1024)
#define SNDBUF_SMALL (128UL * 1024)
#include <net/if.h>
#include <limits.h>
#include <stdint.h>
#include "epoll_type.h"
#include "packet.h"
struct ctx;
/* cppcheck-suppress funcArgNamesDifferent */
__attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
#ifdef CLOSE_RANGE_UNSHARE /* Linux kernel >= 5.9 */
/* glibc < 2.34 and musl as of 1.2.5 need these */
#ifndef SYS_close_range
#define SYS_close_range 436
#endif
__attribute__ ((weak))
/* cppcheck-suppress funcArgNamesDifferent */
int close_range(unsigned int first, unsigned int last, int flags) {
return syscall(SYS_close_range, first, last, flags);
}
#else
/* No reasonable fallback option */
/* cppcheck-suppress funcArgNamesDifferent */
int close_range(unsigned int first, unsigned int last, int flags) {
return 0;
}
#endif
int sock_l4_sa(const struct ctx *c, enum epoll_type type,
const void *sa, socklen_t sl,
const char *ifname, bool v6only, uint32_t data);
int sock_l4(const struct ctx *c, sa_family_t af, enum epoll_type type,
const void *bind_addr, const char *ifname, uint16_t port,
uint32_t data);
void sock_probe_mem(struct ctx *c);
long timespec_diff_ms(const struct timespec *a, const struct timespec *b);
int64_t timespec_diff_us(const struct timespec *a, const struct timespec *b);
void bitmap_set(uint8_t *map, unsigned bit);
void bitmap_clear(uint8_t *map, unsigned bit);
bool bitmap_isset(const uint8_t *map, unsigned bit);
void bitmap_or(uint8_t *dst, size_t size, const uint8_t *a, const uint8_t *b);
char *line_read(char *buf, size_t len, int fd);
void ns_enter(const struct ctx *c);
bool ns_is_init(void);
int open_in_ns(const struct ctx *c, const char *path, int flags);
int pidfile_open(const char *path);
void pidfile_write(int fd, pid_t pid);
int __daemon(int pidfile_fd, int devnull_fd);
int fls(unsigned long x);
int write_file(const char *path, const char *buf);
int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip);
void close_open_files(int argc, char **argv);
/**
* af_name() - Return name of an address family
* @af: Address/protocol family (AF_INET or AF_INET6)
*
* Returns: Name of the protocol family as a string
*/
static inline const char *af_name(sa_family_t af)
{
switch (af) {
case AF_INET:
return "IPv4";
case AF_INET6:
return "IPv6";
default:
return "<unknown address family>";
}
}
#define UINT16_STRLEN (sizeof("65535"))
/* inet address (- '\0') + port (u16) (- '\0') + ':' + '\0' */
#define SOCKADDR_INET_STRLEN \
(INET_ADDRSTRLEN-1 + UINT16_STRLEN-1 + sizeof(":"))
/* inet6 address (- '\0') + port (u16) (- '\0') + '[' + ']' + ':' + '\0' */
#define SOCKADDR_INET6_STRLEN \
(INET6_ADDRSTRLEN-1 + UINT16_STRLEN-1 + sizeof("[]:"))
#define SOCKADDR_STRLEN MAX(SOCKADDR_INET_STRLEN, SOCKADDR_INET6_STRLEN)
#define ETH_ADDRSTRLEN (sizeof("00:11:22:33:44:55"))
struct sock_extended_err;
const char *sockaddr_ntop(const void *sa, char *dst, socklen_t size);
const char *eth_ntop(const unsigned char *mac, char *dst, size_t size);
const char *str_ee_origin(const struct sock_extended_err *ee);
/**
* mod_sub() - Modular arithmetic subtraction
* @a: Minued, unsigned value < @m
* @b: Subtrahend, unsigned value < @m
* @m: Modulus, must be less than (UINT_MAX / 2)
*
* Returns (@a - @b) mod @m, correctly handling unsigned underflows.
*/
static inline unsigned mod_sub(unsigned a, unsigned b, unsigned m)
{
if (a < b)
a += m;
return a - b;
}
/**
* mod_between() - Determine if a value is in a cyclic range
* @x, @i, @j: Unsigned values < @m
* @m: Modulus
*
* Returns true iff @x is in the cyclic range of values from @i..@j (mod @m),
* inclusive of @i, exclusive of @j.
*/
static inline bool mod_between(unsigned x, unsigned i, unsigned j, unsigned m)
{
return mod_sub(x, i, m) < mod_sub(j, i, m);
}
/*
* Workarounds for https://github.com/llvm/llvm-project/issues/58992
*
* For a number (maybe all) system calls that _write_ a socket address,
* clang-tidy doesn't register that the memory of the socket address will be
* initialised after the call. This can't easily be worked around with
* clang-tidy suppressions, because the warning doesn't show on the syscall
* itself but later when we access the supposedly uninitialised field.
*/
static inline void sa_init(struct sockaddr *sa, const socklen_t *sl)
{
#ifdef CLANG_TIDY_58992
if (sa)
memset(sa, 0, *sl);
#else
(void)sa;
(void)sl;
#endif /* CLANG_TIDY_58992 */
}
static inline ssize_t wrap_recvfrom(int sockfd, void *buf, size_t len,
int flags,
struct sockaddr *src_addr,
socklen_t *addrlen)
{
sa_init(src_addr, addrlen);
return recvfrom(sockfd, buf, len, flags, src_addr, addrlen);
}
#define recvfrom(s, buf, len, flags, src, addrlen) \
wrap_recvfrom((s), (buf), (len), (flags), (src), (addrlen))
static inline int wrap_accept4(int sockfd, struct sockaddr *addr,
socklen_t *addrlen, int flags)
{
sa_init(addr, addrlen);
return accept4(sockfd, addr, addrlen, flags);
}
#define accept4(s, addr, addrlen, flags) \
wrap_accept4((s), (addr), (addrlen), (flags))
#endif /* UTIL_H */
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