Re: [PATCH 1/1] cifs: sanitize multiple delimiters in prepath

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fixed various whitespace problems (pointed out by checkpatch), added
the suggested Acked-by, Fixes etc.
and tentatively merged into cifs-2.6.git for-next pending testing

See attached.

On Wed, Dec 15, 2021 at 1:49 PM Leif Sahlberg <lsahlber@xxxxxxxxxx> wrote:
>
> Steve,
>
> Acked-by: me
> Steve, we should have this in stable
>
>     Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
>     Cc: stable@xxxxxxxxxxxxxxx # 5.11+
>
>
> On Wed, Dec 15, 2021 at 1:09 PM Thiago Rafael Becker <trbecker@xxxxxxxxx> wrote:
> >
> > mount.cifs can pass a device with multiple delimiters in it. This will
> > cause rename(2) to fail with ENOENT.
> >
> > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2031200
> > Signed-off-by: Thiago Rafael Becker <trbecker@xxxxxxxxx>
> > ---
> >  fs/cifs/fs_context.c | 30 ++++++++++++++++++++++++++++++
> >  1 file changed, 30 insertions(+)
> >
> > diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
> > index 6a179ae753c1..4ce8a7df3a02 100644
> > --- a/fs/cifs/fs_context.c
> > +++ b/fs/cifs/fs_context.c
> > @@ -434,6 +434,34 @@ int smb3_parse_opt(const char *options, const char *key, char **val)
> >         return rc;
> >  }
> >
> > +/*
> > + * remove duplicate path delimiters. Windows is supposed to do that
> > + * but there are some bugs that prevent rename from working if there are
> > + * multiple delimiters.
> > + */
> > +void sanitize_path(char *path) {
> > +        char *pos = path, last = *path;
> > +        unsigned int offset = 0;
> > +
> > +        while(*(++pos)) {
> > +                if ((*pos == '/' || *pos == '\\') && (last == '/' || last == '\\')) {
> > +                        offset++;
> > +                        continue;
> > +                }
> > +
> > +                last = *pos;
> > +                *(pos - offset) = *pos;
> > +        }
> > +
> > +        pos = pos - offset - 1;
> > +
> > +        /* At this point, there should be only zero or one delimiter at the end of the string */
> > +        if (*pos != '/' && *pos != '\\')
> > +                pos++;
> > +
> > +        *pos = '\0';
> > +}
> > +
> >  /*
> >   * Parse a devname into substrings and populate the ctx->UNC and ctx->prepath
> >   * fields with the result. Returns 0 on success and an error otherwise
> > @@ -497,6 +525,8 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
> >         if (!ctx->prepath)
> >                 return -ENOMEM;
> >
> > +       sanitize_path(ctx->prepath);
> > +
> >         return 0;
> >  }
> >
> > --
> > 2.31.1
> >
>


-- 
Thanks,

Steve
From 859057cc97cc949b0097cd1e776a6708b367e99c Mon Sep 17 00:00:00 2001
From: Thiago Rafael Becker <trbecker@xxxxxxxxx>
Date: Wed, 15 Dec 2021 00:08:31 -0300
Subject: [PATCH] cifs: sanitize multiple delimiters in prepath

mount.cifs can pass a device with multiple delimiters in it. This will
cause rename(2) to fail with ENOENT.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2031200
Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api")
Cc: stable@xxxxxxxxxxxxxxx # 5.11+
Acked-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Signed-off-by: Thiago Rafael Becker <trbecker@xxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
---
 fs/cifs/fs_context.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 6a179ae753c1..4ce8a7df3a02 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -434,6 +434,34 @@ int smb3_parse_opt(const char *options, const char *key, char **val)
 	return rc;
 }
 
+/*
+ * remove duplicate path delimiters. Windows is supposed to do that
+ * but there are some bugs that prevent rename from working if there are
+ * multiple delimiters.
+ */
+void sanitize_path(char *path)
+{
+	char *pos = path, last = *path;
+	unsigned int offset = 0;
+
+	while (*(++pos)) {
+		if ((*pos == '/' || *pos == '\\') && (last == '/' || last == '\\')) {
+			offset++;
+			continue;
+		}
+		last = *pos;
+		*(pos - offset) = *pos;
+	}
+
+	pos = pos - offset - 1;
+
+	/* At this point, there should be only zero or one delimiter at the end of the string */
+	if (*pos != '/' && *pos != '\\')
+		pos++;
+
+	*pos = '\0';
+}
+
 /*
  * Parse a devname into substrings and populate the ctx->UNC and ctx->prepath
  * fields with the result. Returns 0 on success and an error otherwise
@@ -497,6 +525,8 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
 	if (!ctx->prepath)
 		return -ENOMEM;
 
+	sanitize_path(ctx->prepath);
+
 	return 0;
 }
 
-- 
2.32.0


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