Re: [PATCH 2/2] ioctl_store: Extract path checking to its own function

[Owen Smith <owen.smith@xxxxxxxxxx>]

Reviewed-by: Owen Smith <owen.smith@xxxxxxxxxx>

________________________________________
From: win-pv-devel <win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx> on behalf of Tu 
Dinh <ngoc-tu.dinh@xxxxxxxxxx>
Sent: 25 June 2026 9:39 AM
To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
Cc: Tu Dinh
Subject: [PATCH 2/2] ioctl_store: Extract path checking to its own function

xenstore.txt specifies that "The permitted character for paths set is
ASCII alphanumerics and plus the four punctuation characters -/_@
(hyphen slash underscore atsign). @ should be avoided except to specify
special watches."

Create __IsValidPath to check for the above criteria specifically.

Since the '@' character is used for special watches, it is forbidden in
__IsValidPath at the moment.

Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
---
 src/xeniface/ioctl_store.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/xeniface/ioctl_store.c b/src/xeniface/ioctl_store.c
index 2ac96af..bc27b8b 100644
--- a/src/xeniface/ioctl_store.c
+++ b/src/xeniface/ioctl_store.c
@@ -40,6 +40,25 @@
 #define XENSTORE_ABS_PATH_MAX 3072
 #define XENSTORE_REL_PATH_MAX 2048

+static FORCEINLINE
+BOOLEAN
+__IsValidPath(
+    __in  PCHAR             Str,
+    __in  ULONG             Len
+    )
+{
+    for ( ; Len--; ++Str) {
+        if (*Str == '\0')
+            return TRUE;
+        if (*Str != '-' &&
+            *Str != '/' &&
+            *Str != '_' &&
+            !isalnum((unsigned char)*Str))
+            break;
+    }
+    return FALSE;
+}
+
 static FORCEINLINE
 BOOLEAN
 __IsValidStr(
@@ -110,7 +129,7 @@ IoctlStoreRead(
         goto fail1;

     status = STATUS_INVALID_PARAMETER;
-    if (!__IsValidStr(Buffer, InLen))
+    if (!__IsValidPath(Buffer, InLen))
         goto fail2;

     status = XENBUS_STORE(Read, &Fdo->StoreInterface, NULL, NULL, Buffer, 
&Value);
@@ -178,7 +197,7 @@ IoctlStoreWrite(
         goto fail1;

     status = STATUS_INVALID_PARAMETER;
-    if (!__IsValidStr(Buffer, InLen))
+    if (!__IsValidPath(Buffer, InLen))
         goto fail2;

     Length = (ULONG)strlen(Buffer) + 1;
@@ -226,7 +245,7 @@ IoctlStoreDirectory(
         goto fail1;

     status = STATUS_INVALID_PARAMETER;
-    if (!__IsValidStr(Buffer, InLen))
+    if (!__IsValidPath(Buffer, InLen))
         goto fail2;

     status = XENBUS_STORE(Directory, &Fdo->StoreInterface, NULL, NULL, Buffer, 
&Value);
@@ -295,7 +314,7 @@ IoctlStoreRemove(
         goto fail1;

     status = STATUS_INVALID_PARAMETER;
-    if (!__IsValidStr(Buffer, InLen))
+    if (!__IsValidPath(Buffer, InLen))
         goto fail2;

     status = XENBUS_STORE(Remove, &Fdo->StoreInterface, NULL, NULL, Buffer);
@@ -417,7 +436,7 @@ IoctlStoreSetPermissions(

     Path[In->PathLength - 1] = 0;
     status = STATUS_INVALID_PARAMETER;
-    if (!__IsValidStr(Path, In->PathLength))
+    if (!__IsValidPath(Path, In->PathLength))
         goto fail6;

     Trace("> Path '%s', NumberPermissions %lu\n", Path, In->NumberPermissions);
@@ -534,7 +553,7 @@ IoctlStoreAddWatch(

     Path[In->PathLength - 1] = 0;
     status = STATUS_INVALID_PARAMETER;
-    if (!__IsValidStr(Path, In->PathLength))
+    if (!__IsValidPath(Path, In->PathLength))
         goto fail4;

     status = STATUS_NO_MEMORY;
--
2.54.0.windows.1



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