From 505eab7782b429017eb434b2b95120855f2b0e3c Mon Sep 17 00:00:00 2001
From: Chris Liddell <chris.liddell@artifex.com>
Date: Wed, 7 Jun 2023 10:23:06 +0100
Subject: [PATCH] Bug 706761: Don't "reduce" %pipe% file names for permission
 validation

For regular file names, we try to simplfy relative paths before we use them.

Because the %pipe% device can, effectively, accept command line calls, we
shouldn't be simplifying that string, because the command line syntax can end
up confusing the path simplifying code. That can result in permitting a pipe
command which does not match what was originally permitted.

Special case "%pipe" in the validation code so we always deal with the entire
string.
---
 base/gpmisc.c   | 31 +++++++++++++++++++--------
 base/gslibctx.c | 56 ++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 64 insertions(+), 23 deletions(-)

diff --git a/base/gpmisc.c b/base/gpmisc.c
index 5f39ebba7..2fb87f769 100644
--- a/base/gpmisc.c
+++ b/base/gpmisc.c
@@ -1076,16 +1076,29 @@ gp_validate_path_len(const gs_memory_t *mem,
              && !memcmp(path + cdirstrl, dirsepstr, dirsepstrl)) {
           prefix_len = 0;
     }
-    rlen = len+1;
-    bufferfull = (char *)gs_alloc_bytes(mem->thread_safe_memory, rlen + prefix_len, "gp_validate_path");
-    if (bufferfull == NULL)
-        return gs_error_VMerror;
-
-    buffer = bufferfull + prefix_len;
-    if (gp_file_name_reduce(path, (uint)len, buffer, &rlen) != gp_combine_success)
-        return gs_error_invalidfileaccess;
-    buffer[rlen] = 0;
 
+    /* "%pipe%" do not follow the normal rules for path definitions, so we
+       don't "reduce" them to avoid unexpected results
+     */
+    if (len > 5 && memcmp(path, "%pipe", 5) != 0) {
+        bufferfull = buffer = (char *)gs_alloc_bytes(mem->thread_safe_memory, len + 1, "gp_validate_path");
+        if (buffer == NULL)
+            return gs_error_VMerror;
+        memcpy(buffer, path, len);
+        buffer[len] = 0;
+        rlen = len;
+    }
+    else {
+        rlen = len+1;
+        bufferfull = (char *)gs_alloc_bytes(mem->thread_safe_memory, rlen + prefix_len, "gp_validate_path");
+        if (bufferfull == NULL)
+            return gs_error_VMerror;
+
+        buffer = bufferfull + prefix_len;
+        if (gp_file_name_reduce(path, (uint)len, buffer, &rlen) != gp_combine_success)
+            return gs_error_invalidfileaccess;
+        buffer[rlen] = 0;
+    }
     while (1) {
         switch (mode[0])
         {
diff --git a/base/gslibctx.c b/base/gslibctx.c
index eb566ed06..d2a1aa91d 100644
--- a/base/gslibctx.c
+++ b/base/gslibctx.c
@@ -740,14 +740,28 @@ gs_add_control_path_len_flags(const gs_memory_t *mem, gs_path_control_t type, co
             return gs_error_rangecheck;
     }
 
-    rlen = len+1;
-    buffer = (char *)gs_alloc_bytes(core->memory, rlen, "gp_validate_path");
-    if (buffer == NULL)
-        return gs_error_VMerror;
+    /* "%pipe%" do not follow the normal rules for path definitions, so we
+       don't "reduce" them to avoid unexpected results
+     */
+    if (len > 5 && memcmp(path, "%pipe", 5) != 0) {
+        buffer = (char *)gs_alloc_bytes(core->memory, len + 1, "gs_add_control_path_len");
+        if (buffer == NULL)
+            return gs_error_VMerror;
+        memcpy(buffer, path, len);
+        buffer[len] = 0;
+        rlen = len;
+    }
+    else {
+        rlen = len + 1;
 
-    if (gp_file_name_reduce(path, (uint)len, buffer, &rlen) != gp_combine_success)
-        return gs_error_invalidfileaccess;
-    buffer[rlen] = 0;
+        buffer = (char *)gs_alloc_bytes(core->memory, rlen, "gs_add_control_path_len");
+        if (buffer == NULL)
+            return gs_error_VMerror;
+
+        if (gp_file_name_reduce(path, (uint)len, buffer, &rlen) != gp_combine_success)
+            return gs_error_invalidfileaccess;
+        buffer[rlen] = 0;
+    }
 
     n = control->num;
     for (i = 0; i < n; i++)
@@ -833,14 +847,28 @@ gs_remove_control_path_len_flags(const gs_memory_t *mem, gs_path_control_t type,
             return gs_error_rangecheck;
     }
 
-    rlen = len+1;
-    buffer = (char *)gs_alloc_bytes(core->memory, rlen, "gp_validate_path");
-    if (buffer == NULL)
-        return gs_error_VMerror;
+    /* "%pipe%" do not follow the normal rules for path definitions, so we
+       don't "reduce" them to avoid unexpected results
+     */
+    if (len > 5 && memcmp(path, "%pipe", 5) != 0) {
+        buffer = (char *)gs_alloc_bytes(core->memory, len + 1, "gs_remove_control_path_len");
+        if (buffer == NULL)
+            return gs_error_VMerror;
+        memcpy(buffer, path, len);
+        buffer[len] = 0;
+        rlen = len;
+    }
+    else {
+        rlen = len+1;
 
-    if (gp_file_name_reduce(path, (uint)len, buffer, &rlen) != gp_combine_success)
-        return gs_error_invalidfileaccess;
-    buffer[rlen] = 0;
+        buffer = (char *)gs_alloc_bytes(core->memory, rlen, "gs_remove_control_path_len");
+        if (buffer == NULL)
+            return gs_error_VMerror;
+
+        if (gp_file_name_reduce(path, (uint)len, buffer, &rlen) != gp_combine_success)
+            return gs_error_invalidfileaccess;
+        buffer[rlen] = 0;
+    }
 
     n = control->num;
     for (i = 0; i < n; i++) {
-- 
2.34.1