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openssh/misc.h
djm@openbsd.org 81c1099d22
upstream: Add a facility to sshd(8) to penalise particular 
problematic client behaviours, controlled by two new sshd_config(5) options:
PerSourcePenalties and PerSourcePenaltyExemptList.

When PerSourcePenalties are enabled, sshd(8) will monitor the exit
status of its child pre-auth session processes. Through the exit
status, it can observe situations where the session did not
authenticate as expected. These conditions include when the client
repeatedly attempted authentication unsucessfully (possibly indicating
an attack against one or more accounts, e.g. password guessing), or
when client behaviour caused sshd to crash (possibly indicating
attempts to exploit sshd).

When such a condition is observed, sshd will record a penalty of some
duration (e.g. 30 seconds) against the client's address. If this time
is above a minimum threshold specified by the PerSourcePenalties, then
connections from the client address will be refused (along with any
others in the same PerSourceNetBlockSize CIDR range).

Repeated offenses by the same client address will accrue greater
penalties, up to a configurable maximum. A PerSourcePenaltyExemptList
option allows certain address ranges to be exempt from all penalties.

We hope these options will make it significantly more difficult for
attackers to find accounts with weak/guessable passwords or exploit
bugs in sshd(8) itself.

PerSourcePenalties is off by default, but we expect to enable it
automatically in the near future.

much feedback markus@ and others, ok markus@

OpenBSD-Commit-ID: 89ded70eccb2b4926ef0366a4d58a693de366cca
2024-06-07 03:35:40 +10:00

261 lines
9.1 KiB
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/* $OpenBSD: misc.h,v 1.109 2024/06/06 17:15:25 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*/
#ifndef _MISC_H
#define _MISC_H
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <signal.h>
/* special-case port number meaning allow any port */
#define FWD_PERMIT_ANY_PORT 0
/* special-case wildcard meaning allow any host */
#define FWD_PERMIT_ANY_HOST "*"
/* Data structure for representing a forwarding request. */
struct Forward {
char *listen_host; /* Host (address) to listen on. */
int listen_port; /* Port to forward. */
char *listen_path; /* Path to bind domain socket. */
char *connect_host; /* Host to connect. */
int connect_port; /* Port to connect on connect_host. */
char *connect_path; /* Path to connect domain socket. */
int allocated_port; /* Dynamically allocated listen port */
int handle; /* Handle for dynamic listen ports */
};
int forward_equals(const struct Forward *, const struct Forward *);
int permitopen_port(const char *p);
int daemonized(void);
/* Common server and client forwarding options. */
struct ForwardOptions {
int gateway_ports; /* Allow remote connects to forwarded ports. */
mode_t streamlocal_bind_mask; /* umask for streamlocal binds */
int streamlocal_bind_unlink; /* unlink socket before bind */
};
/* misc.c */
char *chop(char *);
void rtrim(char *);
void skip_space(char **);
char *strdelim(char **);
char *strdelimw(char **);
int set_nonblock(int);
int unset_nonblock(int);
void set_nodelay(int);
int set_reuseaddr(int);
char *get_rdomain(int);
int set_rdomain(int, const char *);
int get_sock_af(int);
void set_sock_tos(int, int);
int waitrfd(int, int *, volatile sig_atomic_t *);
int timeout_connect(int, const struct sockaddr *, socklen_t, int *);
int a2port(const char *);
int a2tun(const char *, int *);
char *put_host_port(const char *, u_short);
char *hpdelim2(char **, char *);
char *hpdelim(char **);
char *cleanhostname(char *);
char *colon(char *);
int parse_user_host_path(const char *, char **, char **, char **);
int parse_user_host_port(const char *, char **, char **, int *);
int parse_uri(const char *, const char *, char **, char **, int *, char **);
int convtime(const char *);
const char *fmt_timeframe(time_t t);
int tilde_expand(const char *, uid_t, char **);
char *tilde_expand_filename(const char *, uid_t);
char *dollar_expand(int *, const char *string, ...);
char *percent_expand(const char *, ...) __attribute__((__sentinel__));
char *percent_dollar_expand(const char *, ...) __attribute__((__sentinel__));
char *tohex(const void *, size_t);
void xextendf(char **s, const char *sep, const char *fmt, ...)
__attribute__((__format__ (printf, 3, 4))) __attribute__((__nonnull__ (3)));
void sanitise_stdfd(void);
void ms_subtract_diff(struct timeval *, int *);
void ms_to_timespec(struct timespec *, int);
void monotime_ts(struct timespec *);
void monotime_tv(struct timeval *);
time_t monotime(void);
double monotime_double(void);
void lowercase(char *s);
int unix_listener(const char *, int, int);
int valid_domain(char *, int, const char **);
int valid_env_name(const char *);
const char *atoi_err(const char *, int *);
int parse_absolute_time(const char *, uint64_t *);
void format_absolute_time(uint64_t, char *, size_t);
int parse_pattern_interval(const char *, char **, int *);
int path_absolute(const char *);
int stdfd_devnull(int, int, int);
int lib_contains_symbol(const char *, const char *);
void sock_set_v6only(int);
struct passwd *pwcopy(struct passwd *);
const char *ssh_gai_strerror(int);
typedef void privdrop_fn(struct passwd *);
typedef void privrestore_fn(void);
#define SSH_SUBPROCESS_STDOUT_DISCARD (1) /* Discard stdout */
#define SSH_SUBPROCESS_STDOUT_CAPTURE (1<<1) /* Redirect stdout */
#define SSH_SUBPROCESS_STDERR_DISCARD (1<<2) /* Discard stderr */
#define SSH_SUBPROCESS_UNSAFE_PATH (1<<3) /* Don't check for safe cmd */
#define SSH_SUBPROCESS_PRESERVE_ENV (1<<4) /* Keep parent environment */
pid_t subprocess(const char *, const char *, int, char **, FILE **, u_int,
struct passwd *, privdrop_fn *, privrestore_fn *);
typedef struct arglist arglist;
struct arglist {
char **list;
u_int num;
u_int nalloc;
};
void addargs(arglist *, char *, ...)
__attribute__((format(printf, 2, 3)));
void replacearg(arglist *, u_int, char *, ...)
__attribute__((format(printf, 3, 4)));
void freeargs(arglist *);
int tun_open(int, int, char **);
/* Common definitions for ssh tunnel device forwarding */
#define SSH_TUNMODE_NO 0x00
#define SSH_TUNMODE_POINTOPOINT 0x01
#define SSH_TUNMODE_ETHERNET 0x02
#define SSH_TUNMODE_DEFAULT SSH_TUNMODE_POINTOPOINT
#define SSH_TUNMODE_YES (SSH_TUNMODE_POINTOPOINT|SSH_TUNMODE_ETHERNET)
#define SSH_TUNID_ANY 0x7fffffff
#define SSH_TUNID_ERR (SSH_TUNID_ANY - 1)
#define SSH_TUNID_MAX (SSH_TUNID_ANY - 2)
/* Fake port to indicate that host field is really a path. */
#define PORT_STREAMLOCAL -2
/* Functions to extract or store big-endian words of various sizes */
u_int64_t get_u64(const void *)
__attribute__((__bounded__( __minbytes__, 1, 8)));
u_int32_t get_u32(const void *)
__attribute__((__bounded__( __minbytes__, 1, 4)));
u_int16_t get_u16(const void *)
__attribute__((__bounded__( __minbytes__, 1, 2)));
void put_u64(void *, u_int64_t)
__attribute__((__bounded__( __minbytes__, 1, 8)));
void put_u32(void *, u_int32_t)
__attribute__((__bounded__( __minbytes__, 1, 4)));
void put_u16(void *, u_int16_t)
__attribute__((__bounded__( __minbytes__, 1, 2)));
/* Little-endian store/load, used by umac.c */
u_int32_t get_u32_le(const void *)
__attribute__((__bounded__(__minbytes__, 1, 4)));
void put_u32_le(void *, u_int32_t)
__attribute__((__bounded__(__minbytes__, 1, 4)));
struct bwlimit {
size_t buflen;
u_int64_t rate; /* desired rate in kbit/s */
u_int64_t thresh; /* threshold after which we'll check timers */
u_int64_t lamt; /* amount written in last timer interval */
struct timeval bwstart, bwend;
};
void bandwidth_limit_init(struct bwlimit *, u_int64_t, size_t);
void bandwidth_limit(struct bwlimit *, size_t);
int parse_ipqos(const char *);
const char *iptos2str(int);
void mktemp_proto(char *, size_t);
void child_set_env(char ***envp, u_int *envsizep, const char *name,
const char *value);
const char *lookup_env_in_list(const char *env,
char * const *envs, size_t nenvs);
const char *lookup_setenv_in_list(const char *env,
char * const *envs, size_t nenvs);
int argv_split(const char *, int *, char ***, int);
char *argv_assemble(int, char **argv);
char *argv_next(int *, char ***);
void argv_consume(int *);
void argv_free(char **, int);
int exited_cleanly(pid_t, const char *, const char *, int);
struct stat;
int safe_path(const char *, struct stat *, const char *, uid_t,
char *, size_t);
int safe_path_fd(int, const char *, struct passwd *,
char *err, size_t errlen);
/* authorized_key-style options parsing helpers */
int opt_flag(const char *opt, int allow_negate, const char **optsp);
char *opt_dequote(const char **sp, const char **errstrp);
int opt_match(const char **opts, const char *term);
/* readconf/servconf option lists */
void opt_array_append(const char *file, const int line,
const char *directive, char ***array, u_int *lp, const char *s);
void opt_array_append2(const char *file, const int line,
const char *directive, char ***array, int **iarray, u_int *lp,
const char *s, int i);
void opt_array_free2(char **array, int **iarray, u_int l);
struct timespec;
void ptimeout_init(struct timespec *pt);
void ptimeout_deadline_sec(struct timespec *pt, long sec);
void ptimeout_deadline_ms(struct timespec *pt, long ms);
void ptimeout_deadline_monotime_tsp(struct timespec *pt, struct timespec *when);
void ptimeout_deadline_monotime(struct timespec *pt, time_t when);
int ptimeout_get_ms(struct timespec *pt);
struct timespec *ptimeout_get_tsp(struct timespec *pt);
int ptimeout_isset(struct timespec *pt);
/* readpass.c */
#define RP_ECHO 0x0001
#define RP_ALLOW_STDIN 0x0002
#define RP_ALLOW_EOF 0x0004
#define RP_USE_ASKPASS 0x0008
struct notifier_ctx;
char *read_passphrase(const char *, int);
int ask_permission(const char *, ...) __attribute__((format(printf, 1, 2)));
struct notifier_ctx *notify_start(int, const char *, ...)
__attribute__((format(printf, 2, 3)));
void notify_complete(struct notifier_ctx *, const char *, ...)
__attribute__((format(printf, 2, 3)));
#define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
#define MAXIMUM(a, b) (((a) > (b)) ? (a) : (b))
#define ROUNDUP(x, y) ((((x)+((y)-1))/(y))*(y))
typedef void (*sshsig_t)(int);
sshsig_t ssh_signal(int, sshsig_t);
int signal_is_crash(int);
/* On OpenBSD time_t is int64_t which is long long. */
/* #define SSH_TIME_T_MAX LLONG_MAX */
#endif /* _MISC_H */
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