diff options
| -rw-r--r-- | networking/ftpd.c | 196 |
1 files changed, 107 insertions, 89 deletions
diff --git a/networking/ftpd.c b/networking/ftpd.c index 37b340e..22cec83 100644 --- a/networking/ftpd.c +++ b/networking/ftpd.c @@ -66,9 +66,9 @@ /* Convert a constant to 3-digit string, packed into uint32_t */ enum { /* Shift for Nth decimal digit */ - SHIFT0 = 16 * BB_LITTLE_ENDIAN + 8 * BB_BIG_ENDIAN, - SHIFT1 = 8 * BB_LITTLE_ENDIAN + 16 * BB_BIG_ENDIAN, SHIFT2 = 0 * BB_LITTLE_ENDIAN + 24 * BB_BIG_ENDIAN, + SHIFT1 = 8 * BB_LITTLE_ENDIAN + 16 * BB_BIG_ENDIAN, + SHIFT0 = 16 * BB_LITTLE_ENDIAN + 8 * BB_BIG_ENDIAN, }; #define STRNUM32(s) (uint32_t)(0 \ | (('0' + ((s) / 1 % 10)) << SHIFT0) \ @@ -76,47 +76,6 @@ enum { | (('0' + ((s) / 100 % 10)) << SHIFT2) \ ) -enum { - OPT_l = (1 << 0), - OPT_1 = (1 << 1), - OPT_v = (1 << 2), - OPT_S = (1 << 3), - OPT_w = (1 << 4), - -#define mk_const4(a,b,c,d) (((a * 0x100 + b) * 0x100 + c) * 0x100 + d) -#define mk_const3(a,b,c) ((a * 0x100 + b) * 0x100 + c) - const_ALLO = mk_const4('A', 'L', 'L', 'O'), - const_APPE = mk_const4('A', 'P', 'P', 'E'), - const_CDUP = mk_const4('C', 'D', 'U', 'P'), - const_CWD = mk_const3('C', 'W', 'D'), - const_DELE = mk_const4('D', 'E', 'L', 'E'), - const_EPSV = mk_const4('E', 'P', 'S', 'V'), - const_HELP = mk_const4('H', 'E', 'L', 'P'), - const_LIST = mk_const4('L', 'I', 'S', 'T'), - const_MKD = mk_const3('M', 'K', 'D'), - const_MODE = mk_const4('M', 'O', 'D', 'E'), - const_NLST = mk_const4('N', 'L', 'S', 'T'), - const_NOOP = mk_const4('N', 'O', 'O', 'P'), - const_PASS = mk_const4('P', 'A', 'S', 'S'), - const_PASV = mk_const4('P', 'A', 'S', 'V'), - const_PORT = mk_const4('P', 'O', 'R', 'T'), - const_PWD = mk_const3('P', 'W', 'D'), - const_QUIT = mk_const4('Q', 'U', 'I', 'T'), - const_REST = mk_const4('R', 'E', 'S', 'T'), - const_RETR = mk_const4('R', 'E', 'T', 'R'), - const_RMD = mk_const3('R', 'M', 'D'), - const_RNFR = mk_const4('R', 'N', 'F', 'R'), - const_RNTO = mk_const4('R', 'N', 'T', 'O'), - const_SIZE = mk_const4('S', 'I', 'Z', 'E'), - const_STAT = mk_const4('S', 'T', 'A', 'T'), - const_STOR = mk_const4('S', 'T', 'O', 'R'), - const_STOU = mk_const4('S', 'T', 'O', 'U'), - const_STRU = mk_const4('S', 'T', 'R', 'U'), - const_SYST = mk_const4('S', 'Y', 'S', 'T'), - const_TYPE = mk_const4('T', 'Y', 'P', 'E'), - const_USER = mk_const4('U', 'S', 'E', 'R'), -}; - struct globals { char *p_control_line_buf; len_and_sockaddr *local_addr; @@ -182,21 +141,16 @@ replace_char(char *str, char from, char to) return p - str; } +/* NB: status_str is char[4] packed into uint32_t */ static void cmdio_write(uint32_t status_str, const char *str) { - union { - char buf[4]; - uint32_t v32; - } u; char *response; int len; - u.v32 = status_str; - /* FTP allegedly uses telnet protocol for command link. * In telnet, 0xff is an escape char, and needs to be escaped: */ - response = escape_text(u.buf, str, (0xff << 8) + '\r'); + response = escape_text((char *) &status_str, str, (0xff << 8) + '\r'); /* ?! does FTP send embedded LFs as NULs? wow */ len = replace_char(response, '\n', '\0'); @@ -444,46 +398,58 @@ handle_epsv(void) static void handle_port(void) { - unsigned short port; - char *raw, *port_part; - len_and_sockaddr *lsa; + unsigned port, port_hi; + char *raw, *comma; + socklen_t peer_ipv4_len; + struct sockaddr_in peer_ipv4; + struct in_addr port_ipv4_sin_addr; port_pasv_cleanup(); raw = G.ftp_arg; -/* Buglets: - * xatou16 will accept wrong input, - * xatou16 will exit instead of generating error to peer - */ + /* PORT command format makes sense only over IPv4 */ + if (!raw || G.local_addr->u.sa.sa_family != AF_INET) { + bail: + cmdio_write_error(FTP_BADCMD); + return; + } - port_part = strrchr(raw, ','); - if (port_part == NULL) + comma = strrchr(raw, ','); + if (comma == NULL) + goto bail; + *comma = '\0'; + port = bb_strtou(&comma[1], NULL, 10); + if (errno || port > 0xff) goto bail; - port = xatou16(&port_part[1]); - *port_part = '\0'; - port_part = strrchr(raw, ','); - if (port_part == NULL) + comma = strrchr(raw, ','); + if (comma == NULL) goto bail; - port |= xatou16(&port_part[1]) << 8; - *port_part = '\0'; + *comma = '\0'; + port_hi = bb_strtou(&comma[1], NULL, 10); + if (errno || port_hi > 0xff) + goto bail; + port |= port_hi << 8; replace_char(raw, ',', '.'); - lsa = xdotted2sockaddr(raw, port); - if (lsa == NULL) { - bail: - cmdio_write_error(FTP_BADCMD); - return; - } - -/* Should we verify that lsa matches getpeername(STDIN)? - * Otherwise peer can make us open data connections - * to other hosts (security problem!) - */ + /* We are verifying that PORT's IP matches getpeername(). + * Otherwise peer can make us open data connections + * to other hosts (security problem!) + * This code would be too simplistic: + * lsa = xdotted2sockaddr(raw, port); + * if (lsa == NULL) goto bail; + */ + if (!inet_aton(raw, &port_ipv4_sin_addr)) + goto bail; + peer_ipv4_len = sizeof(peer_ipv4); + if (getpeername(STDIN_FILENO, &peer_ipv4, &peer_ipv4_len) != 0) + goto bail; + if (memcmp(&port_ipv4_sin_addr, &peer_ipv4.sin_addr, sizeof(struct in_addr)) != 0) + goto bail; - G.port_addr = lsa; + G.port_addr = xdotted2sockaddr(raw, port); cmdio_write_ok(FTP_PORTOK); } @@ -612,6 +578,8 @@ handle_dir_common(int opts) if (!(opts & USE_CTRL_CONN) && !port_or_pasv_was_seen()) return; /* port_or_pasv_was_seen emitted error response */ + /* -n prevents user/groupname display, + * which can be problematic in chroot */ ls_fd = popen_ls((opts & LONG_LISTING) ? "-l" : "-1"); ls_fp = fdopen(ls_fd, "r"); if (!ls_fp) /* never happens. paranoia */ @@ -749,11 +717,12 @@ handle_rnto(void) static void handle_upload_common(int is_append, int is_unique) { - char *tempname = NULL; + struct stat statbuf; + char *tempname; off_t bytes_transferred; + off_t offset; int local_file_fd; int remote_fd; - off_t offset; offset = G.restart_pos; G.restart_pos = 0; @@ -761,6 +730,7 @@ handle_upload_common(int is_append, int is_unique) if (!port_or_pasv_was_seen()) return; /* port_or_pasv_was_seen emitted error response */ + tempname = NULL; local_file_fd = -1; if (is_unique) { tempname = xstrdup(" FILE: uniq.XXXXXX"); @@ -773,13 +743,17 @@ handle_upload_common(int is_append, int is_unique) flags = O_WRONLY | O_CREAT; local_file_fd = open(G.ftp_arg, flags, 0666); } - if (local_file_fd < 0) { + + if (local_file_fd < 0 + || fstat(local_file_fd, &statbuf) != 0 + || !S_ISREG(statbuf.st_mode) + ) { cmdio_write_error(FTP_UPLOADFAIL); + if (local_file_fd >= 0) + goto close_local_and_bail; return; } -/* TODO: paranoia: fstat it, refuse to do anything if it's not a regular file */ - if (offset) xlseek(local_file_fd, offset, SEEK_SET); @@ -787,7 +761,7 @@ handle_upload_common(int is_append, int is_unique) free(tempname); if (remote_fd < 0) - goto bail; + goto close_local_and_bail; /* TODO: if we'll implement timeout, this will need more clever handling. * Perhaps alarm(N) + checking that current position on local_file_fd @@ -800,7 +774,8 @@ handle_upload_common(int is_append, int is_unique) cmdio_write_error(FTP_BADSENDFILE); else cmdio_write_ok(FTP_TRANSFEROK); - bail: + + close_local_and_bail: close(local_file_fd); } @@ -838,17 +813,18 @@ cmdio_get_cmd_and_arg(void) if (!cmd) exit(0); + /* Trailing '\n' is already stripped, strip '\r' */ len = strlen(cmd) - 1; - while (len >= 0 && cmd[len] == '\r') { + while ((ssize_t)len >= 0 && cmd[len] == '\r') { cmd[len] = '\0'; len--; } G.ftp_arg = strchr(cmd, ' '); - if (G.ftp_arg != NULL) { - *G.ftp_arg = '\0'; - G.ftp_arg++; - } + if (G.ftp_arg != NULL) + *G.ftp_arg++ = '\0'; + + /* Uppercase and pack into uint32_t first word of the command */ cmdval = 0; while (*cmd) cmdval = (cmdval << 8) + ((unsigned char)*cmd++ & (unsigned char)~0x20); @@ -856,6 +832,47 @@ cmdio_get_cmd_and_arg(void) return cmdval; } +#define mk_const4(a,b,c,d) (((a * 0x100 + b) * 0x100 + c) * 0x100 + d) +#define mk_const3(a,b,c) ((a * 0x100 + b) * 0x100 + c) +enum { + const_ALLO = mk_const4('A', 'L', 'L', 'O'), + const_APPE = mk_const4('A', 'P', 'P', 'E'), + const_CDUP = mk_const4('C', 'D', 'U', 'P'), + const_CWD = mk_const3('C', 'W', 'D'), + const_DELE = mk_const4('D', 'E', 'L', 'E'), + const_EPSV = mk_const4('E', 'P', 'S', 'V'), + const_HELP = mk_const4('H', 'E', 'L', 'P'), + const_LIST = mk_const4('L', 'I', 'S', 'T'), + const_MKD = mk_const3('M', 'K', 'D'), + const_MODE = mk_const4('M', 'O', 'D', 'E'), + const_NLST = mk_const4('N', 'L', 'S', 'T'), + const_NOOP = mk_const4('N', 'O', 'O', 'P'), + const_PASS = mk_const4('P', 'A', 'S', 'S'), + const_PASV = mk_const4('P', 'A', 'S', 'V'), + const_PORT = mk_const4('P', 'O', 'R', 'T'), + const_PWD = mk_const3('P', 'W', 'D'), + const_QUIT = mk_const4('Q', 'U', 'I', 'T'), + const_REST = mk_const4('R', 'E', 'S', 'T'), + const_RETR = mk_const4('R', 'E', 'T', 'R'), + const_RMD = mk_const3('R', 'M', 'D'), + const_RNFR = mk_const4('R', 'N', 'F', 'R'), + const_RNTO = mk_const4('R', 'N', 'T', 'O'), + const_SIZE = mk_const4('S', 'I', 'Z', 'E'), + const_STAT = mk_const4('S', 'T', 'A', 'T'), + const_STOR = mk_const4('S', 'T', 'O', 'R'), + const_STOU = mk_const4('S', 'T', 'O', 'U'), + const_STRU = mk_const4('S', 'T', 'R', 'U'), + const_SYST = mk_const4('S', 'Y', 'S', 'T'), + const_TYPE = mk_const4('T', 'Y', 'P', 'E'), + const_USER = mk_const4('U', 'S', 'E', 'R'), + + OPT_l = (1 << 0), + OPT_1 = (1 << 1), + OPT_v = (1 << 2), + OPT_S = (1 << 3), + OPT_w = (1 << 4), +}; + int ftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int ftpd_main(int argc, char **argv) { @@ -865,6 +882,7 @@ int ftpd_main(int argc, char **argv) if (opts & (OPT_l|OPT_1)) { /* Our secret backdoor to ls */ +/* TODO: pass -n too? */ xchdir(argv[2]); argv[2] = (char*)"--"; return ls_main(argc, argv); |