d7e6af2dd

Denis Vlasenko

2008-03-18

FAILED Duration: 20s

Subject

tftpd: make open() check r/w permissions instead of doing it ourself. Add -r "prohibit upload" opt for those lazy people who run tftpd as root. -40 bytes.

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 →

include/usage.h +4 -2 networking/tftp.c +27 -21

include/usage.h+4 -2

@@ -3977,9 +3977,11 @@
	)

	#define tftpd_trivial_usage \
-	"[DIR]"
+	"[-r] [DIR]"
	#define tftpd_full_usage \
-	"Transfer a file on request from a tftp client" \
+	"Transfer a file on request from a tftp client.\n" \
+	"\nOptions:" \
+	"\n -r Prohibit upload" \

	#define time_trivial_usage \
	"[OPTION]... COMMAND [ARGS...]"

networking/tftp.c+27 -21

@@ -56,6 +56,8 @@
	* CMD_GET(cmd) and CMD_PUT(cmd) are mutually exclusive
	*/

+	// TODO: emit error packets before dying
+

	#if ENABLE_FEATURE_TFTP_BLOCKSIZE

@@ -340,7 +342,7 @@ static int tftp_protocol(

	const char *msg = "";

-	if (rbuf[4] != '\0') {
+	if (len > 4 && rbuf[4] != '\0') {
	msg = &rbuf[4];
	rbuf[tftp_bufsize - 1] = '\0';
	} else if (recv_blk < ARRAY_SIZE(errcode_str)) {
@@ -533,14 +535,14 @@ 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 ATTRIBUTE_UNUSED)
+	int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv)
	{
-	struct stat statbuf;
	char block_buf[TFTP_BLOCKSIZE_DEFAULT];
	len_and_sockaddr *our_lsa;
	len_and_sockaddr *peer_lsa;
	char filename, mode, *opt_str;
-	int result, opcode, cmd, req_modebits, open_mode, local_fd, blksize;
+	int opt_r, result, opcode, open_mode, local_fd, blksize;
+	USE_GETPUT(int cmd;)

	our_lsa = get_sock_lsa(STDIN_FILENO);
	if (!our_lsa)
@@ -548,8 +550,10 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
	peer_lsa = xzalloc(LSA_LEN_SIZE + our_lsa->len);
	peer_lsa->len = our_lsa->len;

-	if (argv[1])
-	xchdir(argv[1]);
+	opt_r = getopt32(argv, "r");
+	argv += optind;
+	if (argv[0])
+	xchdir(argv[0]);

	result = recv_from_to(STDIN_FILENO, block_buf, sizeof(block_buf),
	0 /* flags */,
@@ -558,7 +562,10 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
	opcode = ntohs((uint16_t)block_buf);
	if (result < 4 \|\| result >= sizeof(block_buf)
	\|\| block_buf[result-1] != '\0'
-	\|\| (opcode != TFTP_RRQ && opcode != TFTP_WRQ)
+	\|\| (USE_FEATURE_TFTP_GET(opcode != TFTP_RRQ) /* not download */
+	USE_GETPUT(&&)
+	USE_FEATURE_TFTP_GET(opcode != TFTP_WRQ) /* not upload */
+	)
	) {
	bb_error_msg_and_die("malformed packet");
	}
@@ -584,21 +591,20 @@ int tftpd_main(int argc ATTRIBUTE_UNUSED, char **argv ATTRIBUTE_UNUSED)
	}
	}
	#endif
-	xstat(filename, &statbuf);
-	/* if opcode == TFTP_WRQ: */
-	cmd = 1; /* CMD_GET: we will receive file's data */
-	req_modebits = 0222; /* writable by anyone */
-	open_mode = O_WRONLY \| O_TRUNC;
-	if (opcode == TFTP_RRQ) {
-	cmd = 2; /* CMD_PUT */
-	req_modebits = 0444; /* readable by anyone */
-	open_mode = O_RDONLY;
-	}
-	if (!S_ISREG(statbuf.st_mode)
-	\|\| (statbuf.st_mode & req_modebits) != req_modebits
-	) {
-	bb_error_msg_and_die("access to '%s' is denied", filename);
+
+	#if ENABLE_FEATURE_TFTP_PUT
+	/* in case opcode is TFTP_RRQ: */
+	USE_GETPUT(cmd = 2;) /* CMD_PUT: we will send file's data */
+	open_mode = O_RDONLY;
+	#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");
+	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);

	close(STDIN_FILENO); /* close old, possibly wildcard socket */