From 9a92dec1dcc618051500908a1f24761ab29abdcb Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Mon, 10 Jun 2024 20:36:22 -0700
Subject: [PATCH] tftpd: make it possible to adjust the remap deadman

Allow the user to tweak the remap deadman counter if it is necessary
for whatever reason.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 tftpd/remap.c    | 10 ++++++----
 tftpd/remap.h    |  3 +++
 tftpd/tftpd.8.in |  4 ++++
 tftpd/tftpd.c    | 14 ++++++++++++++
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/tftpd/remap.c b/tftpd/remap.c
index d74b2db..6497cad 100644
--- a/tftpd/remap.c
+++ b/tftpd/remap.c
@@ -39,6 +39,8 @@
 #define RULE_WRQ	0x400	/* Put (write) only */
 #define RULE_SEDG	0x800   /* sed-style global */
 
+int deadman_max_steps = DEADMAN_MAX_STEPS;
+
 struct rule {
     struct rule *next;
     int nrule;
@@ -397,7 +399,7 @@ char *rewrite_string(const struct formats *pf,
     int i;
     int len, newlen;
     int was_match = 0;
-    int deadman = DEADMAN_MAX_STEPS;
+    int deadman = deadman_max_steps;
     int matchsense;
     int pmatches;
     unsigned int bad_flags;
@@ -534,9 +536,9 @@ char *rewrite_string(const struct formats *pf,
     return current;
 
 dead:                           /* Deadman expired */
-    syslog(LOG_WARNING,
-           "remap: Breaking loop, input = %s, last = %s", input,
-           current);
+    syslog(LOG_ERR,
+           "remap: Breaking loop after %d steps, input = %s, last = %s",
+           deadman_max_steps, input, current);
     free(current);
     return NULL;        /* Did not terminate! */
 }
diff --git a/tftpd/remap.h b/tftpd/remap.h
index a9954ab..c8d76ff 100644
--- a/tftpd/remap.h
+++ b/tftpd/remap.h
@@ -40,5 +40,8 @@ char *rewrite_string(const struct formats *, const char *,
 		     const struct rule *, int, int,
                      match_pattern_callback, const char **);
 
+/* Remapping deadman counter */
+extern int deadman_max_steps;
+
 #endif                          /* WITH_REGEX */
 #endif                          /* TFTPD_REMAP_H */
diff --git a/tftpd/tftpd.8.in b/tftpd/tftpd.8.in
index 9baf7fd..3d43325 100644
--- a/tftpd/tftpd.8.in
+++ b/tftpd/tftpd.8.in
@@ -163,6 +163,10 @@ remapping below.  This option may not be compiled in, see the output of
 .B "in.tftpd \-V"
 to verify whether or not it is available.
 .TP
+.\fB\-\-map-steps\fP \fIsteps\fP
+Specify the number of remapping rules that may be executed before the
+filename mapping fails. The default is 4096.
+.TP
 \fB\-\-verbose\fP, \fB\-v\fP
 Increase the logging verbosity of
 .BR tftpd .
diff --git a/tftpd/tftpd.c b/tftpd/tftpd.c
index bec0f34..fc7e54a 100644
--- a/tftpd/tftpd.c
+++ b/tftpd/tftpd.c
@@ -325,6 +325,7 @@ static int split_port(char **ap, char **pp)
 
 enum long_only_options {
     OPT_VERBOSITY	= 256,
+    OPT_MAP_STEPS
 };
 
 static struct option long_options[] = {
@@ -347,6 +348,7 @@ static struct option long_options[] = {
     { "retransmit",  1, NULL, 'T' },
     { "port-range",  1, NULL, 'R' },
     { "map-file",    1, NULL, 'm' },
+    { "map-steps",   1, NULL, OPT_MAP_STEPS },
     { "pidfile",     1, NULL, 'P' },
     { NULL, 0, NULL, 0 }
 };
@@ -495,6 +497,18 @@ int main(int argc, char **argv)
             }
             rewrite_file = optarg;
             break;
+        case OPT_MAP_STEPS:
+        {
+            char *ep;
+            unsigned long steps = strtoul(optarg, &ep, 0);
+            if (*optarg && *ep && steps > 0 && steps <= INT_MAX) {
+                deadman_max_steps = steps;
+            } else {
+                syslog(LOG_ERR, "Bad --map-steps option: %s", optarg);
+                exit(EX_USAGE);
+            }
+            break;
+        }
 #endif
         case 'v':
             verbosity++;
-- 
2.11.4.GIT