tftpd: make it emit error packets

telnetd: use login always, not "sometimes login, sometimes shell"

   text    data     bss     dec     hex filename
 797612     641    7380  805633   c4b01 busybox_old
 797695     641    7380  805716   c4b54 busybox_unstripped
This commit is contained in:
Denis Vlasenko 2008-03-19 05:00:05 +00:00
parent c0183e6e0d
commit dd9228b861
2 changed files with 183 additions and 123 deletions

View File

@ -56,11 +56,7 @@ enum { BUFSIZE = (4 * 1024 - sizeof(struct tsession)) / 2 };
/* Globals */
static int maxfd;
static struct tsession *sessions;
#if ENABLE_LOGIN
static const char *loginpath = "/bin/login";
#else
static const char *loginpath = DEFAULT_SHELL;
#endif
static const char *issuefile = "/etc/issue.net";

View File

@ -25,7 +25,7 @@
#if ENABLE_FEATURE_TFTP_GET || ENABLE_FEATURE_TFTP_PUT
#define TFTP_BLOCKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
#define TFTP_BLKSIZE_DEFAULT 512 /* according to RFC 1350, don't change */
#define TFTP_TIMEOUT_MS 50
#define TFTP_MAXTIMEOUT_MS 2000
#define TFTP_NUM_RETRIES 12 /* number of backed-off retries */
@ -38,6 +38,17 @@
#define TFTP_ERROR 5
#define TFTP_OACK 6
/* error codes sent over network */
#define ERR_UNSPEC 0
#define ERR_NOFILE 1
#define ERR_ACCESS 2
#define ERR_WRITE 3
#define ERR_OP 4
#define ERR_BAD_ID 5
#define ERR_EXIST 6
#define ERR_BAD_USER 7
#define ERR_BAD_OPT 8
#if ENABLE_FEATURE_TFTP_GET && !ENABLE_FEATURE_TFTP_PUT
#define USE_GETPUT(...)
#define CMD_GET(cmd) 1
@ -56,29 +67,48 @@
* CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
*/
// TODO: emit error packets before dying
struct globals {
/* u16 TFTP_ERROR; u16 reason; both network-endian, then error text: */
uint8_t error_pkt[4 + 32];
/* used in tftpd_main(), a bit big fro stack: */
char block_buf[TFTP_BLKSIZE_DEFAULT];
};
#define G (*(struct globals*)&bb_common_bufsiz1)
#define block_buf (G.block_buf )
#define error_pkt (G.error_pkt )
#define INIT_G() \
do { \
} while (0)
#define error_pkt_reason (error_pkt[3])
#define error_pkt_str (error_pkt + 4)
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
static int tftp_blocksize_check(int blocksize, int bufsize)
static int tftp_blksize_check(const char *blksize_str, int maxsize)
{
/* Check if the blocksize is valid:
/* Check if the blksize is valid:
* RFC2348 says between 8 and 65464,
* but our implementation makes it impossible
* to use blocksizes smaller than 22 octets.
*/
if ((bufsize && (blocksize > bufsize))
|| (blocksize < 24) || (blocksize > 65564)
* to use blksizes smaller than 22 octets. */
unsigned blksize = bb_strtou(blksize_str, NULL, 10);
if (errno
|| (blksize < 24) || (blksize > maxsize)
) {
bb_error_msg("bad blocksize");
return 0;
bb_error_msg("bad blocksize '%s'", blksize_str);
return -1;
}
return blocksize;
#if ENABLE_DEBUG_TFTP
bb_error_msg("using blksize %u", blksize);
#endif
return blksize;
}
static char *tftp_option_get(char *buf, int len, const char *option)
static char *tftp_get_blksize(char *buf, int len)
{
#define option "blksize"
int opt_val = 0;
int opt_found = 0;
int k;
@ -110,6 +140,7 @@ static char *tftp_option_get(char *buf, int len, const char *option)
}
return NULL;
#undef option
}
#endif
@ -120,7 +151,7 @@ static int tftp_protocol(
len_and_sockaddr *peer_lsa,
USE_TFTP(const char *remote_file,)
int local_fd,
int blocksize)
int blksize)
{
#if !ENABLE_TFTP
#define remote_file NULL
@ -135,14 +166,14 @@ static int tftp_protocol(
uint16_t block_nr;
uint16_t recv_blk;
int retries, waittime_ms;
int tftp_bufsize = blocksize + 4;
int io_bufsize = blksize + 4;
char *cp;
/* Can't use RESERVE_CONFIG_BUFFER here since the allocation
* size varies meaning BUFFERS_GO_ON_STACK would fail */
/* We must keep the transmit and receive buffers seperate */
/* In case we rcv a garbage pkt and we need to rexmit the last pkt */
char *xbuf = xmalloc(tftp_bufsize);
char *rbuf = xmalloc(tftp_bufsize);
char *xbuf = xmalloc(io_bufsize);
char *rbuf = xmalloc(io_bufsize);
socket_fd = xsocket(peer_lsa->u.sa.sa_family, SOCK_DGRAM, 0);
setsockopt_reuseaddr(socket_fd);
@ -160,6 +191,10 @@ static int tftp_protocol(
xbind(socket_fd, &our_lsa->u.sa, our_lsa->len);
xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
/* Is there an error already? Send pkt and bail out */
if (error_pkt_reason || error_pkt_str[0])
goto send_err_pkt;
if (CMD_GET(cmd)) {
/* it's upload - we must ACK 1st packet (with filename)
* as if it's "block 0" */
@ -167,10 +202,11 @@ static int tftp_protocol(
}
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (blocksize != TFTP_BLOCKSIZE_DEFAULT) {
if (blksize != TFTP_BLKSIZE_DEFAULT) {
/* Create and send OACK packet */
/* block_nr is still 1, we expect ACK to (block_nr-1),
* that is, to "block 0" */
/* For the download case, block_nr is still 1 -
* we expect 1st ACK from peer to be for (block_nr-1),
* that is, for "block 0" which is our OACK pkt */
opcode = TFTP_OACK;
cp = xbuf + 2;
goto add_blksize_opt;
@ -200,7 +236,7 @@ static int tftp_protocol(
/* add filename and mode */
/* fill in packet if the filename fits into xbuf */
len = strlen(remote_file) + 1;
if (2 + len + sizeof("octet") >= tftp_bufsize) {
if (2 + len + sizeof("octet") >= io_bufsize) {
bb_error_msg("remote filename is too long");
goto ret;
}
@ -211,18 +247,18 @@ static int tftp_protocol(
cp += sizeof("octet");
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (blocksize != TFTP_BLOCKSIZE_DEFAULT) {
if (blksize != TFTP_BLKSIZE_DEFAULT) {
/* rfc2348 says that 65464 is a max allowed value */
if ((&xbuf[tftp_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
if ((&xbuf[io_bufsize - 1] - cp) < sizeof("blksize NNNNN")) {
bb_error_msg("remote filename is too long");
goto ret;
}
want_option_ack = 1;
add_blksize_opt:
/* add "blksize", <nul>, blocksize, <nul> */
/* add "blksize", <nul>, blksize, <nul> */
strcpy(cp, "blksize");
cp += sizeof("blksize");
cp += snprintf(cp, 6, "%d", blocksize) + 1;
cp += snprintf(cp, 6, "%d", blksize) + 1;
}
#endif
/* First packet is built, so skip packet generation */
@ -240,12 +276,11 @@ static int tftp_protocol(
opcode = TFTP_ACK;
if (CMD_PUT(cmd)) {
opcode = TFTP_DATA;
len = full_read(local_fd, cp, tftp_bufsize - 4);
len = full_read(local_fd, cp, blksize);
if (len < 0) {
bb_perror_msg(bb_msg_read_error);
goto ret;
goto send_read_err_pkt;
}
if (len != (tftp_bufsize - 4)) {
if (len != blksize) {
finished = 1;
}
cp += len;
@ -277,34 +312,14 @@ static int tftp_protocol(
/*pfd[0].fd = socket_fd;*/
pfd[0].events = POLLIN;
switch (safe_poll(pfd, 1, waittime_ms)) {
case 1:
if (!our_lsa) {
/* tftp (not tftpd!) receiving 1st packet */
our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
len = recvfrom(socket_fd, rbuf, tftp_bufsize, 0,
&peer_lsa->u.sa, &peer_lsa->len);
/* Our first dgram went to port 69
* but reply may come from different one.
* Remember and use this new port (and IP) */
if (len >= 0)
xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
} else {
/* tftpd, or not the very first packet:
* socket is connect()ed, can just read from it. */
len = safe_read(socket_fd, rbuf, tftp_bufsize);
}
if (len < 0) {
bb_perror_msg("read");
default:
/*bb_perror_msg("poll"); - done in safe_poll */
goto ret;
}
if (len < 4) /* too small? */
goto recv_again;
goto process_pkt;
case 0:
retries--;
if (retries == 0) {
bb_error_msg("timeout");
goto ret;
goto ret; /* no err packet sent */
}
/* exponential backoff with limit */
@ -314,39 +329,58 @@ static int tftp_protocol(
}
goto send_again; /* resend last sent pkt */
default:
/*bb_perror_msg("poll"); - done in safe_poll */
goto ret;
case 1:
if (!our_lsa) {
/* tftp (not tftpd!) receiving 1st packet */
our_lsa = ((void*)(ptrdiff_t)-1); /* not NULL */
len = recvfrom(socket_fd, rbuf, io_bufsize, 0,
&peer_lsa->u.sa, &peer_lsa->len);
/* Our first dgram went to port 69
* but reply may come from different one.
* Remember and use this new port (and IP) */
if (len >= 0)
xconnect(socket_fd, &peer_lsa->u.sa, peer_lsa->len);
} else {
/* tftpd, or not the very first packet:
* socket is connect()ed, can just read from it. */
/* Don't full_read()!
* This is not TCP, one read == one pkt! */
len = safe_read(socket_fd, rbuf, io_bufsize);
}
process_pkt:
if (len < 0) {
goto send_read_err_pkt;
}
if (len < 4) { /* too small? */
goto recv_again;
}
}
/* Process recv'ed packet */
opcode = ntohs( ((uint16_t*)rbuf)[0] );
recv_blk = ntohs( ((uint16_t*)rbuf)[1] );
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "received %d bytes: %04x %04x\n", len, opcode, recv_blk);
#endif
if (opcode == TFTP_ERROR) {
static const char *const errcode_str[] = {
"",
"file not found",
"access violation",
"disk full",
"illegal TFTP operation",
"unknown transfer id",
"file already exists",
"no such user",
"bad option"
};
static const char errcode_str[] =
"\0"
"file not found\0"
"access violation\0"
"disk full\0"
"bad operation\0"
"unknown transfer id\0"
"file already exists\0"
"no such user\0"
"bad option";
const char *msg = "";
if (len > 4 && rbuf[4] != '\0') {
msg = &rbuf[4];
rbuf[tftp_bufsize - 1] = '\0';
} else if (recv_blk < ARRAY_SIZE(errcode_str)) {
msg = errcode_str[recv_blk];
rbuf[io_bufsize - 1] = '\0'; /* paranoia */
} else if (recv_blk <= 8) {
msg = nth_string(errcode_str, recv_blk);
}
bb_error_msg("server error: (%u) %s", recv_blk, msg);
goto ret;
@ -355,29 +389,18 @@ static int tftp_protocol(
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (want_option_ack) {
want_option_ack = 0;
if (opcode == TFTP_OACK) {
/* server seems to support options */
char *res;
res = tftp_option_get(&rbuf[2], len - 2, "blksize");
res = tftp_get_blksize(&rbuf[2], len - 2);
if (res) {
int blksize = xatoi_u(res);
if (!tftp_blocksize_check(blksize, tftp_bufsize - 4)) {
/* send ERROR 8 to server... */
/* htons can be impossible to use in const initializer: */
/*static const uint16_t error_8[2] = { htons(TFTP_ERROR), htons(8) };*/
/* thus we open-code big-endian layout */
static const uint8_t error_8[4] = { 0,TFTP_ERROR, 0,8 };
xsendto(socket_fd, error_8, 4, &peer_lsa->u.sa, peer_lsa->len);
bb_error_msg("server proposes bad blksize %d, exiting", blksize);
goto ret;
blksize = tftp_blksize_check(res, blksize);
if (blksize < 0) {
error_pkt_reason = ERR_BAD_OPT;
goto send_err_pkt;
}
#if ENABLE_DEBUG_TFTP
fprintf(stderr, "using blksize %u\n",
blksize);
#endif
tftp_bufsize = blksize + 4;
io_bufsize = blksize + 4;
/* Send ACK for OACK ("block" no: 0) */
block_nr = 0;
continue;
@ -387,10 +410,9 @@ static int tftp_protocol(
* must be ignored by the client and server
* as if it were never requested." */
}
bb_error_msg("blksize is not supported by server"
" - reverting to 512");
tftp_bufsize = TFTP_BLOCKSIZE_DEFAULT + 4;
bb_error_msg("server only supports blocksize of 512");
blksize = TFTP_BLKSIZE_DEFAULT;
io_bufsize = TFTP_BLKSIZE_DEFAULT + 4;
}
#endif
/* block_nr is already advanced to next block# we expect
@ -401,9 +423,10 @@ static int tftp_protocol(
len = full_write(local_fd, &rbuf[4], len - 4);
if (len < 0) {
bb_perror_msg(bb_msg_write_error);
goto ret;
error_pkt_reason = ERR_WRITE;
goto send_err_pkt;
}
if (len != (tftp_bufsize - 4)) {
if (len != blksize) {
finished = 1;
}
continue; /* send ACK */
@ -442,6 +465,15 @@ static int tftp_protocol(
free(rbuf);
}
return finished == 0; /* returns 1 on failure */
send_read_err_pkt:
bb_perror_msg(bb_msg_read_error);
strcpy(error_pkt_str, bb_msg_read_error);
send_err_pkt:
error_pkt[1] = TFTP_ERROR;
xsendto(socket_fd, error_pkt, 4 + 1 + strlen(error_pkt_str),
&peer_lsa->u.sa, peer_lsa->len);
return EXIT_FAILURE;
}
#if ENABLE_TFTP
@ -457,18 +489,20 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
int local_fd;
int flags = 0;
int result;
int blocksize = TFTP_BLOCKSIZE_DEFAULT;
int blksize;
const char *blksize_str = "512";
INIT_G();
/* -p or -g is mandatory, and they are mutually exclusive */
opt_complementary = "" USE_FEATURE_TFTP_GET("g:") USE_FEATURE_TFTP_PUT("p:")
USE_GETPUT("g--p:p--g:")
USE_FEATURE_TFTP_BLOCKSIZE("b+");
USE_GETPUT("g--p:p--g:");
USE_GETPUT(cmd =) getopt32(argv,
USE_FEATURE_TFTP_GET("g") USE_FEATURE_TFTP_PUT("p")
"l:r:" USE_FEATURE_TFTP_BLOCKSIZE("b:"),
&local_file, &remote_file
USE_FEATURE_TFTP_BLOCKSIZE(, &blocksize));
USE_FEATURE_TFTP_BLOCKSIZE(, &blksize_str));
argv += optind;
flags = O_RDONLY;
@ -476,8 +510,13 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
flags = O_WRONLY | O_CREAT | O_TRUNC;
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (!tftp_blocksize_check(blocksize, 0))
/* Check if the blksize is valid:
* RFC2348 says between 8 and 65464 */
blksize = tftp_blksize_check(blksize_str, 65564);
if (blksize < 0) {
//bb_error_msg("bad block size");
return EXIT_FAILURE;
}
#endif
if (!local_file)
@ -506,7 +545,7 @@ int tftp_main(int argc ATTRIBUTE_UNUSED, char **argv)
USE_GETPUT(cmd,)
NULL /* our_lsa*/,
peer_lsa,
remote_file, local_fd, blocksize);
remote_file, local_fd, blksize);
if (ENABLE_FEATURE_CLEAN_UP)
close(local_fd);
@ -537,12 +576,16 @@ static len_and_sockaddr *get_sock_lsa(int s)
int tftpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
{
char block_buf[TFTP_BLOCKSIZE_DEFAULT];
len_and_sockaddr *our_lsa;
len_and_sockaddr *peer_lsa;
char *filename, *mode, *opt_str;
int opt_r, result, opcode, open_mode, local_fd, blksize;
USE_GETPUT(int cmd;)
char *filename, *mode;
const char *error_msg;
int opt_r, result, opcode, open_mode;
int local_fd = local_fd; /* for compiler */
int blksize = blksize;
USE_GETPUT(int cmd = cmd;)
INIT_G();
our_lsa = get_sock_lsa(STDIN_FILENO);
if (!our_lsa)
@ -559,6 +602,7 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
0 /* flags */,
&peer_lsa->u.sa, &our_lsa->u.sa, our_lsa->len);
error_msg = "malformed packet";
opcode = ntohs(*(uint16_t*)block_buf);
if (result < 4 || result >= sizeof(block_buf)
|| block_buf[result-1] != '\0'
@ -567,27 +611,35 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
USE_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
)
) {
bb_error_msg_and_die("malformed packet");
goto err;
}
filename = block_buf + 2;
if (filename[0] == '.' || strstr(filename, "/.")) {
bb_error_msg_and_die("dot in filename");
error_msg = "dot in filename";
goto err;
}
mode = filename + strlen(filename) + 1;
if (mode >= block_buf + sizeof(block_buf)
if (mode >= block_buf + result
|| strcmp(mode, "octet") != 0
) {
bb_error_msg_and_die("malformed packet");
goto err;
}
blksize = TFTP_BLOCKSIZE_DEFAULT;
blksize = TFTP_BLKSIZE_DEFAULT;
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
opt_str = mode + 6;
if (opt_str < block_buf + sizeof(block_buf)) {
char *res = tftp_option_get(opt_str, block_buf + sizeof(block_buf) - opt_str, "blksize");
{
char *res;
char *opt_str = mode + sizeof("octet");
int opt_len = block_buf + result - opt_str;
if (opt_len > 0) {
res = tftp_get_blksize(opt_str, opt_len);
if (res) {
int sz = xatoi_u(res);
if (tftp_blocksize_check(sz, 0))
blksize = sz;
blksize = tftp_blksize_check(res, 65564);
if (blksize < 0) {
error_pkt_reason = ERR_BAD_OPT;
/* will just send error pkt */
goto do_proto;
}
}
}
}
#endif
@ -599,16 +651,28 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
#endif
#if ENABLE_FEATURE_TFTP_GET
if (!ENABLE_FEATURE_TFTP_PUT || opcode == TFTP_WRQ) {
if (opt_r)
bb_error_msg_and_die("upload is prohibited");
if (opt_r) {
error_pkt_reason = ERR_WRITE;
/* will just send error pkt */
goto do_proto;
}
USE_GETPUT(cmd = 1;) /* CMD_GET: we will receive file's data */
open_mode = O_WRONLY | O_TRUNC;
}
#endif
local_fd = xopen(filename, open_mode);
local_fd = open(filename, open_mode);
if (local_fd < 0) {
error_msg = "can't open file";
err:
strcpy(error_pkt_str, error_msg);
}
close(STDIN_FILENO); /* close old, possibly wildcard socket */
/* tftp_protocol() will create new one, bound to particular local IP */
/* NB: if error_pkt_str or error_pkt_reason is set up,
* tftp_protocol() just sends one error pkt and returns */
do_proto:
result = tftp_protocol(
USE_GETPUT(cmd,)
our_lsa, peer_lsa,