← Commit list

dd9228b86

Denis Vlasenko
Denis Vlasenko
2008-03-19
FAILED Duration: 18s

Subject

tftpd: make it emit error packets telnetd: use login always, not "sometimes login, sometimes shell"

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

networking/telnetd.c +0 -4networking/tftp.c +178 -114
networking/telnetd.c+0 -4
@@ -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";
networking/tftp.c+178 -114
@@ -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;
@@ -277,11 +312,28 @@ static int tftp_protocol(
/*pfd[0].fd = socket_fd;*/
pfd[0].events = POLLIN;
switch (safe_poll(pfd, 1, waittime_ms)) {
+ default:
+ /*bb_perror_msg("poll"); - done in safe_poll */
+ goto ret;
+ case 0:
+ retries--;
+ if (retries == 0) {
+ bb_error_msg("timeout");
+ goto ret; /* no err packet sent */
+ }
+
+ /* exponential backoff with limit */
+ waittime_ms += waittime_ms/2;
+ if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
+ waittime_ms = TFTP_MAXTIMEOUT_MS;
+ }
+
+ goto send_again; /* resend last sent pkt */
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,
+ 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.
@@ -291,62 +343,44 @@ static int tftp_protocol(
} 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);
+ /* Don't full_read()!
+ * This is not TCP, one read == one pkt! */
+ len = safe_read(socket_fd, rbuf, io_bufsize);
}
if (len < 0) {
- bb_perror_msg("read");
- goto ret;
+ goto send_read_err_pkt;
}
- if (len < 4) /* too small? */
+ if (len < 4) { /* too small? */
goto recv_again;
- goto process_pkt;
- case 0:
- retries--;
- if (retries == 0) {
- bb_error_msg("timeout");
- goto ret;
}
-
- /* exponential backoff with limit */
- waittime_ms += waittime_ms/2;
- if (waittime_ms > TFTP_MAXTIMEOUT_MS) {
- waittime_ms = TFTP_MAXTIMEOUT_MS;
- }
-
- goto send_again; /* resend last sent pkt */
- default:
- /*bb_perror_msg("poll"); - done in safe_poll */
- goto ret;
}
- process_pkt:
+
/* 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");
- if (res) {
- int sz = xatoi_u(res);
- if (tftp_blocksize_check(sz, 0))
- blksize = sz;
+ {
+ 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) {
+ 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,