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* [PATCH] cifs: fix regression when mounting shares with prefix paths
@ 2021-04-30 22:16 Paulo Alcantara
  2021-04-30 23:40 ` David Disseldorp
  2021-05-03 14:55 ` [PATCH v2] " Paulo Alcantara
  0 siblings, 2 replies; 7+ messages in thread
From: Paulo Alcantara @ 2021-04-30 22:16 UTC (permalink / raw)
  To: linux-cifs, smfrench; +Cc: ddiss, aaptel, Paulo Alcantara, stable

The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
revealed an existing bug when mounting shares that contain a prefix
path or DFS links.

cifs_setup_volume_info() requires the @devname to contain the full
path (UNC + prefix) to update the fs context with the new UNC and
prepath values, however we were passing only the UNC
path (old_ctx->UNC) in @device thus discarding any prefix paths.

Instead of concatenating both old_ctx->{UNC,prepath} and pass it in
@devname, just keep the dup'ed values of UNC and prepath in
cifs_sb->ctx after calling smb3_fs_context_dup(), and fix
smb3_parse_devname() to correctly parse and not leak the new UNC and
prefix paths.

Cc: <stable@vger.kernel.org> # v5.11+
Fixes: 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
---
 fs/cifs/cifsfs.c     |  8 +-------
 fs/cifs/connect.c    | 25 +++++++++++++++++--------
 fs/cifs/fs_context.c |  4 ++++
 3 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 8a6894577697..d7ea9c5fe0f8 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -863,13 +863,7 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 		goto out;
 	}
 
-	/* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */
-	kfree(cifs_sb->ctx->UNC);
-	cifs_sb->ctx->UNC = NULL;
-	kfree(cifs_sb->ctx->prepath);
-	cifs_sb->ctx->prepath = NULL;
-
-	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
+	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);
 	if (rc) {
 		root = ERR_PTR(rc);
 		goto out;
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index becd5f807787..04a06e22e715 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3159,19 +3159,28 @@ static int do_dfs_failover(const char *path, const char *full_path, struct cifs_
 int
 cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const char *devname)
 {
-	int rc = 0;
+	int rc;
 
-	smb3_parse_devname(devname, ctx);
+	if (devname) {
+		cifs_dbg(FYI, "%s: devname=%s\n", __func__, devname);
+		rc = smb3_parse_devname(devname, ctx);
+		if (rc) {
+			cifs_dbg(VFS, "%s: failed to parse %s: %d\n", __func__, devname, rc);
+			return rc;
+		}
+	}
 
 	if (mntopts) {
 		char *ip;
 
-		cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts);
 		rc = smb3_parse_opt(mntopts, "ip", &ip);
-		if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip,
-						 strlen(ip))) {
-			cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
-			return -EINVAL;
+		if (!rc) {
+			rc = cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip));
+			kfree(ip);
+			if (!rc) {
+				cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
+				return -EINVAL;
+			}
 		}
 	}
 
@@ -3189,7 +3198,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c
 		return -EINVAL;
 	}
 
-	return rc;
+	return 0;
 }
 
 static int
diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 1d6e0e15b034..3bcf881c3ae9 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -476,6 +476,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
 
 	/* move "pos" up to delimiter or NULL */
 	pos += len;
+	kfree(ctx->UNC);
 	ctx->UNC = kstrndup(devname, pos - devname, GFP_KERNEL);
 	if (!ctx->UNC)
 		return -ENOMEM;
@@ -486,6 +487,9 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
 	if (*pos == '/' || *pos == '\\')
 		pos++;
 
+	kfree(ctx->prepath);
+	ctx->prepath = NULL;
+
 	/* If pos is NULL then no prepath */
 	if (!*pos)
 		return 0;
-- 
2.31.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] cifs: fix regression when mounting shares with prefix paths
  2021-04-30 22:16 [PATCH] cifs: fix regression when mounting shares with prefix paths Paulo Alcantara
@ 2021-04-30 23:40 ` David Disseldorp
  2021-05-03 12:41   ` Paulo Alcantara
  2021-05-03 14:55 ` [PATCH v2] " Paulo Alcantara
  1 sibling, 1 reply; 7+ messages in thread
From: David Disseldorp @ 2021-04-30 23:40 UTC (permalink / raw)
  To: Paulo Alcantara; +Cc: linux-cifs, smfrench, aaptel, stable

On Fri, 30 Apr 2021 19:16:21 -0300, Paulo Alcantara wrote:

> The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
> revealed an existing bug when mounting shares that contain a prefix
> path or DFS links.

Sorry for the mess. One question...

...
>  	if (mntopts) {
>  		char *ip;
>  
> -		cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts);
>  		rc = smb3_parse_opt(mntopts, "ip", &ip);
> -		if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip,
> -						 strlen(ip))) {
> -			cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
> -			return -EINVAL;
> +		if (!rc) {
> +			rc = cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip));
> +			kfree(ip);
> +			if (!rc) {
> +				cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
> +				return -EINVAL;
> +			}
>  		}
>  	}
>  
> @@ -3189,7 +3198,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c
>  		return -EINVAL;
>  	}
>  
> -	return rc;
> +	return 0;
>  }

It seems that smb3_parse_opt() errors will no longer be propagated here.
Is that intentional?

Cheers, David

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] cifs: fix regression when mounting shares with prefix paths
  2021-04-30 23:40 ` David Disseldorp
@ 2021-05-03 12:41   ` Paulo Alcantara
  0 siblings, 0 replies; 7+ messages in thread
From: Paulo Alcantara @ 2021-05-03 12:41 UTC (permalink / raw)
  To: David Disseldorp; +Cc: linux-cifs, smfrench, aaptel, stable

David Disseldorp <ddiss@suse.de> writes:

> On Fri, 30 Apr 2021 19:16:21 -0300, Paulo Alcantara wrote:
>
>> The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
>> revealed an existing bug when mounting shares that contain a prefix
>> path or DFS links.
>
> Sorry for the mess. One question...
>
> ...
>>  	if (mntopts) {
>>  		char *ip;
>>  
>> -		cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts);
>>  		rc = smb3_parse_opt(mntopts, "ip", &ip);
>> -		if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip,
>> -						 strlen(ip))) {
>> -			cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
>> -			return -EINVAL;
>> +		if (!rc) {
>> +			rc = cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip));
>> +			kfree(ip);
>> +			if (!rc) {
>> +				cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
>> +				return -EINVAL;
>> +			}
>>  		}
>>  	}
>>  
>> @@ -3189,7 +3198,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c
>>  		return -EINVAL;
>>  	}
>>  
>> -	return rc;
>> +	return 0;
>>  }
>
> It seems that smb3_parse_opt() errors will no longer be propagated here.
> Is that intentional?

That was a mistake, actually.  Will fix it in v2.  Thanks!

^ permalink raw reply	[flat|nested] 7+ messages in thread

* [PATCH v2] cifs: fix regression when mounting shares with prefix paths
  2021-04-30 22:16 [PATCH] cifs: fix regression when mounting shares with prefix paths Paulo Alcantara
  2021-04-30 23:40 ` David Disseldorp
@ 2021-05-03 14:55 ` Paulo Alcantara
  2021-05-03 23:20   ` David Disseldorp
  1 sibling, 1 reply; 7+ messages in thread
From: Paulo Alcantara @ 2021-05-03 14:55 UTC (permalink / raw)
  To: linux-cifs, smfrench; +Cc: ddiss, aaptel, Paulo Alcantara, stable

The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
revealed an existing bug when mounting shares that contain a prefix
path or DFS links.

cifs_setup_volume_info() requires the @devname to contain the full
path (UNC + prefix) to update the fs context with the new UNC and
prepath values, however we were passing only the UNC
path (old_ctx->UNC) in @device thus discarding any prefix paths.

Instead of concatenating both old_ctx->{UNC,prepath} and pass it in
@devname, just keep the dup'ed values of UNC and prepath in
cifs_sb->ctx after calling smb3_fs_context_dup(), and fix
smb3_parse_devname() to correctly parse and not leak the new UNC and
prefix paths.

Cc: <stable@vger.kernel.org> # v5.11+
Fixes: 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
---
 fs/cifs/cifsfs.c     |  8 +-------
 fs/cifs/connect.c    | 24 ++++++++++++++++++------
 fs/cifs/fs_context.c |  4 ++++
 3 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 8a6894577697..d7ea9c5fe0f8 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -863,13 +863,7 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
 		goto out;
 	}
 
-	/* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */
-	kfree(cifs_sb->ctx->UNC);
-	cifs_sb->ctx->UNC = NULL;
-	kfree(cifs_sb->ctx->prepath);
-	cifs_sb->ctx->prepath = NULL;
-
-	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
+	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);
 	if (rc) {
 		root = ERR_PTR(rc);
 		goto out;
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index becd5f807787..4ce6fc24cae1 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3159,17 +3159,29 @@ static int do_dfs_failover(const char *path, const char *full_path, struct cifs_
 int
 cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const char *devname)
 {
-	int rc = 0;
+	int rc;
 
-	smb3_parse_devname(devname, ctx);
+	if (devname) {
+		cifs_dbg(FYI, "%s: devname=%s\n", __func__, devname);
+		rc = smb3_parse_devname(devname, ctx);
+		if (rc) {
+			cifs_dbg(VFS, "%s: failed to parse %s: %d\n", __func__, devname, rc);
+			return rc;
+		}
+	}
 
 	if (mntopts) {
 		char *ip;
 
-		cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts);
 		rc = smb3_parse_opt(mntopts, "ip", &ip);
-		if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip,
-						 strlen(ip))) {
+		if (rc) {
+			cifs_dbg(VFS, "%s: failed to parse ip options: %d\n", __func__, rc);
+			return rc;
+		}
+
+		rc = cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip));
+		kfree(ip);
+		if (!rc) {
 			cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
 			return -EINVAL;
 		}
@@ -3189,7 +3201,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c
 		return -EINVAL;
 	}
 
-	return rc;
+	return 0;
 }
 
 static int
diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c
index 1d6e0e15b034..3bcf881c3ae9 100644
--- a/fs/cifs/fs_context.c
+++ b/fs/cifs/fs_context.c
@@ -476,6 +476,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
 
 	/* move "pos" up to delimiter or NULL */
 	pos += len;
+	kfree(ctx->UNC);
 	ctx->UNC = kstrndup(devname, pos - devname, GFP_KERNEL);
 	if (!ctx->UNC)
 		return -ENOMEM;
@@ -486,6 +487,9 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)
 	if (*pos == '/' || *pos == '\\')
 		pos++;
 
+	kfree(ctx->prepath);
+	ctx->prepath = NULL;
+
 	/* If pos is NULL then no prepath */
 	if (!*pos)
 		return 0;
-- 
2.31.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH v2] cifs: fix regression when mounting shares with prefix paths
  2021-05-03 14:55 ` [PATCH v2] " Paulo Alcantara
@ 2021-05-03 23:20   ` David Disseldorp
  2021-05-04 16:47     ` Paulo Alcantara
  2021-05-04 16:58     ` Steve French
  0 siblings, 2 replies; 7+ messages in thread
From: David Disseldorp @ 2021-05-03 23:20 UTC (permalink / raw)
  To: Paulo Alcantara; +Cc: linux-cifs, smfrench, aaptel, stable

On Mon,  3 May 2021 11:55:26 -0300, Paulo Alcantara wrote:

> The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
> revealed an existing bug when mounting shares that contain a prefix
> path or DFS links.
> 
> cifs_setup_volume_info() requires the @devname to contain the full
> path (UNC + prefix) to update the fs context with the new UNC and
> prepath values, however we were passing only the UNC
> path (old_ctx->UNC) in @device thus discarding any prefix paths.
> 
> Instead of concatenating both old_ctx->{UNC,prepath} and pass it in
> @devname, just keep the dup'ed values of UNC and prepath in
> cifs_sb->ctx after calling smb3_fs_context_dup(), and fix
> smb3_parse_devname() to correctly parse and not leak the new UNC and
> prefix paths.
> 
> Cc: <stable@vger.kernel.org> # v5.11+
> Fixes: 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
> Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
> ---
>  fs/cifs/cifsfs.c     |  8 +-------
>  fs/cifs/connect.c    | 24 ++++++++++++++++++------
>  fs/cifs/fs_context.c |  4 ++++
>  3 files changed, 23 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 8a6894577697..d7ea9c5fe0f8 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -863,13 +863,7 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
>  		goto out;
>  	}
>  
> -	/* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */
> -	kfree(cifs_sb->ctx->UNC);
> -	cifs_sb->ctx->UNC = NULL;
> -	kfree(cifs_sb->ctx->prepath);
> -	cifs_sb->ctx->prepath = NULL;
> -
> -	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
> +	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);

IIUC, with the new behaviour, this call becomes pretty much an
	if (!cifs_sb->ctx->username)
		root = ERR_PTR(-EINVAL);

So it might be worth simplifying this further. Either way:
Acked-by: David Disseldorp <ddiss@suse.de>

Cheers, David

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH v2] cifs: fix regression when mounting shares with prefix paths
  2021-05-03 23:20   ` David Disseldorp
@ 2021-05-04 16:47     ` Paulo Alcantara
  2021-05-04 16:58     ` Steve French
  1 sibling, 0 replies; 7+ messages in thread
From: Paulo Alcantara @ 2021-05-04 16:47 UTC (permalink / raw)
  To: David Disseldorp; +Cc: linux-cifs, smfrench, aaptel, stable

David Disseldorp <ddiss@suse.de> writes:

> On Mon,  3 May 2021 11:55:26 -0300, Paulo Alcantara wrote:
>> -	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
>> +	rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);
>
> IIUC, with the new behaviour, this call becomes pretty much an
> 	if (!cifs_sb->ctx->username)
> 		root = ERR_PTR(-EINVAL);

Yeah.  We should get rid of the damn thing at some point.  I've just
tried to keep the logic we currently have in fs/cifs/connect.c by
composing new options based upon the chased DFS referrals.

Thanks for pointing it out!

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH v2] cifs: fix regression when mounting shares with prefix paths
  2021-05-03 23:20   ` David Disseldorp
  2021-05-04 16:47     ` Paulo Alcantara
@ 2021-05-04 16:58     ` Steve French
  1 sibling, 0 replies; 7+ messages in thread
From: Steve French @ 2021-05-04 16:58 UTC (permalink / raw)
  To: David Disseldorp; +Cc: Paulo Alcantara, CIFS, Aurélien Aptel, Stable

added acked-by and merged into cifs-2.6.git for-next

On Mon, May 3, 2021 at 6:20 PM David Disseldorp <ddiss@suse.de> wrote:
>
> On Mon,  3 May 2021 11:55:26 -0300, Paulo Alcantara wrote:
>
> > The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
> > revealed an existing bug when mounting shares that contain a prefix
> > path or DFS links.
> >
> > cifs_setup_volume_info() requires the @devname to contain the full
> > path (UNC + prefix) to update the fs context with the new UNC and
> > prepath values, however we were passing only the UNC
> > path (old_ctx->UNC) in @device thus discarding any prefix paths.
> >
> > Instead of concatenating both old_ctx->{UNC,prepath} and pass it in
> > @devname, just keep the dup'ed values of UNC and prepath in
> > cifs_sb->ctx after calling smb3_fs_context_dup(), and fix
> > smb3_parse_devname() to correctly parse and not leak the new UNC and
> > prefix paths.
> >
> > Cc: <stable@vger.kernel.org> # v5.11+
> > Fixes: 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx")
> > Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
> > ---
> >  fs/cifs/cifsfs.c     |  8 +-------
> >  fs/cifs/connect.c    | 24 ++++++++++++++++++------
> >  fs/cifs/fs_context.c |  4 ++++
> >  3 files changed, 23 insertions(+), 13 deletions(-)
> >
> > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> > index 8a6894577697..d7ea9c5fe0f8 100644
> > --- a/fs/cifs/cifsfs.c
> > +++ b/fs/cifs/cifsfs.c
> > @@ -863,13 +863,7 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
> >               goto out;
> >       }
> >
> > -     /* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */
> > -     kfree(cifs_sb->ctx->UNC);
> > -     cifs_sb->ctx->UNC = NULL;
> > -     kfree(cifs_sb->ctx->prepath);
> > -     cifs_sb->ctx->prepath = NULL;
> > -
> > -     rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
> > +     rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);
>
> IIUC, with the new behaviour, this call becomes pretty much an
>         if (!cifs_sb->ctx->username)
>                 root = ERR_PTR(-EINVAL);
>
> So it might be worth simplifying this further. Either way:
> Acked-by: David Disseldorp <ddiss@suse.de>
>
> Cheers, David



-- 
Thanks,

Steve

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-05-04 16:58 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-30 22:16 [PATCH] cifs: fix regression when mounting shares with prefix paths Paulo Alcantara
2021-04-30 23:40 ` David Disseldorp
2021-05-03 12:41   ` Paulo Alcantara
2021-05-03 14:55 ` [PATCH v2] " Paulo Alcantara
2021-05-03 23:20   ` David Disseldorp
2021-05-04 16:47     ` Paulo Alcantara
2021-05-04 16:58     ` Steve French

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