int sshbuf_reserve(struct sshbuf *buf, size_t len, u_char **dpp) { size_t rlen, need; u_char *dp; int r; if (dpp != NULL) *dpp = NULL; SSHBUF_DBG(("reserve buf = %p len = %zu", buf, len)); if ((r = sshbuf_check_reserve(buf, len)) != 0) return r; /* * If the requested allocation appended would push us past max_size * then pack the buffer, zeroing buf->off. */ sshbuf_maybe_pack(buf, buf->size + len > buf->max_size); SSHBUF_TELL("reserve"); if (len + buf->size > buf->alloc) { /* * Prefer to alloc in SSHBUF_SIZE_INC units, but * allocate less if doing so would overflow max_size. */ need = len + buf->size - buf->alloc; rlen = roundup(buf->alloc + need, SSHBUF_SIZE_INC); SSHBUF_DBG(("need %zu initial rlen %zu", need, rlen)); if (rlen > buf->max_size) rlen = buf->alloc + need; SSHBUF_DBG(("adjusted rlen %zu", rlen)); if ((dp = realloc(buf->d, rlen)) == NULL) { SSHBUF_DBG(("realloc fail")); if (dpp != NULL) *dpp = NULL; return SSH_ERR_ALLOC_FAIL; } buf->alloc = rlen; buf->cd = buf->d = dp; if ((r = sshbuf_check_reserve(buf, len)) < 0) { /* shouldn't fail */ if (dpp != NULL) *dpp = NULL; return r; } } dp = buf->d + buf->size; buf->size += len; SSHBUF_TELL("done"); if (dpp != NULL) *dpp = dp; return 0; }
int buffer_check_alloc(Buffer *buffer, u_int len) { int ret = sshbuf_check_reserve(buffer, len); if (ret == 0) return 1; if (ret == SSH_ERR_NO_BUFFER_SPACE) return 0; fatal("%s: %s", __func__, ssh_err(ret)); }
int sftp_server_main(int argc, char **argv, struct passwd *user_pw) { fd_set *rset, *wset; int i, r, in, out, max, ch, skipargs = 0, log_stderr = 0; ssize_t len, olen, set_size; SyslogFacility log_facility = SYSLOG_FACILITY_AUTH; char *cp, *homedir = NULL, buf[4*4096]; long mask; extern char *optarg; extern char *__progname; ssh_malloc_init(); /* must be called before any mallocs */ __progname = ssh_get_progname(argv[0]); log_init(__progname, log_level, log_facility, log_stderr); pw = pwcopy(user_pw); while (!skipargs && (ch = getopt(argc, argv, "d:f:l:P:p:Q:u:cehR")) != -1) { switch (ch) { case 'Q': if (strcasecmp(optarg, "requests") != 0) { fprintf(stderr, "Invalid query type\n"); exit(1); } for (i = 0; handlers[i].handler != NULL; i++) printf("%s\n", handlers[i].name); for (i = 0; extended_handlers[i].handler != NULL; i++) printf("%s\n", extended_handlers[i].name); exit(0); break; case 'R': readonly = 1; break; case 'c': /* * Ignore all arguments if we are invoked as a * shell using "sftp-server -c command" */ skipargs = 1; break; case 'e': log_stderr = 1; break; case 'l': log_level = log_level_number(optarg); if (log_level == SYSLOG_LEVEL_NOT_SET) error("Invalid log level \"%s\"", optarg); break; case 'f': log_facility = log_facility_number(optarg); if (log_facility == SYSLOG_FACILITY_NOT_SET) error("Invalid log facility \"%s\"", optarg); break; case 'd': cp = tilde_expand_filename(optarg, user_pw->pw_uid); homedir = percent_expand(cp, "d", user_pw->pw_dir, "u", user_pw->pw_name, (char *)NULL); free(cp); break; case 'p': if (request_whitelist != NULL) fatal("Permitted requests already set"); request_whitelist = xstrdup(optarg); break; case 'P': if (request_blacklist != NULL) fatal("Refused requests already set"); request_blacklist = xstrdup(optarg); break; case 'u': errno = 0; mask = strtol(optarg, &cp, 8); if (mask < 0 || mask > 0777 || *cp != '\0' || cp == optarg || (mask == 0 && errno != 0)) fatal("Invalid umask \"%s\"", optarg); (void)umask((mode_t)mask); break; case 'h': default: sftp_server_usage(); } } log_init(__progname, log_level, log_facility, log_stderr); #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) /* * On Linux, we should try to avoid making /proc/self/{mem,maps} * available to the user so that sftp access doesn't automatically * imply arbitrary code execution access that will break * restricted configurations. */ if (prctl(PR_SET_DUMPABLE, 0) != 0) fatal("unable to make the process undumpable"); #endif /* defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) */ /* Drop any fine-grained privileges we don't need */ platform_pledge_sftp_server(); if ((cp = getenv("SSH_CONNECTION")) != NULL) { client_addr = xstrdup(cp); if ((cp = strchr(client_addr, ' ')) == NULL) { error("Malformed SSH_CONNECTION variable: \"%s\"", getenv("SSH_CONNECTION")); sftp_server_cleanup_exit(255); } *cp = '\0'; } else client_addr = xstrdup("UNKNOWN"); logit("session opened for local user %s from [%s]", pw->pw_name, client_addr); in = STDIN_FILENO; out = STDOUT_FILENO; #ifdef HAVE_CYGWIN setmode(in, O_BINARY); setmode(out, O_BINARY); #endif max = 0; if (in > max) max = in; if (out > max) max = out; if ((iqueue = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); if ((oqueue = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); rset = xcalloc(howmany(max + 1, NFDBITS), sizeof(fd_mask)); wset = xcalloc(howmany(max + 1, NFDBITS), sizeof(fd_mask)); if (homedir != NULL) { if (chdir(homedir) != 0) { error("chdir to \"%s\" failed: %s", homedir, strerror(errno)); } } set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask); for (;;) { memset(rset, 0, set_size); memset(wset, 0, set_size); /* * Ensure that we can read a full buffer and handle * the worst-case length packet it can generate, * otherwise apply backpressure by stopping reads. */ if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 && (r = sshbuf_check_reserve(oqueue, SFTP_MAX_MSG_LENGTH)) == 0) FD_SET(in, rset); else if (r != SSH_ERR_NO_BUFFER_SPACE) fatal("%s: sshbuf_check_reserve failed: %s", __func__, ssh_err(r)); olen = sshbuf_len(oqueue); if (olen > 0) FD_SET(out, wset); if (select(max+1, rset, wset, NULL, NULL) < 0) { if (errno == EINTR) continue; error("select: %s", strerror(errno)); sftp_server_cleanup_exit(2); } /* copy stdin to iqueue */ if (FD_ISSET(in, rset)) { len = read(in, buf, sizeof buf); if (len == 0) { debug("read eof"); sftp_server_cleanup_exit(0); } else if (len < 0) { error("read: %s", strerror(errno)); sftp_server_cleanup_exit(1); } else if ((r = sshbuf_put(iqueue, buf, len)) != 0) { fatal("%s: buffer error: %s", __func__, ssh_err(r)); } } /* send oqueue to stdout */ if (FD_ISSET(out, wset)) { len = write(out, sshbuf_ptr(oqueue), olen); if (len < 0) { error("write: %s", strerror(errno)); sftp_server_cleanup_exit(1); } else if ((r = sshbuf_consume(oqueue, len)) != 0) { fatal("%s: buffer error: %s", __func__, ssh_err(r)); } } /* * Process requests from client if we can fit the results * into the output buffer, otherwise stop processing input * and let the output queue drain. */ r = sshbuf_check_reserve(oqueue, SFTP_MAX_MSG_LENGTH); if (r == 0) process(); else if (r != SSH_ERR_NO_BUFFER_SPACE) fatal("%s: sshbuf_check_reserve: %s", __func__, ssh_err(r)); } }