[PATCH] mount: parse default values correctly

[PATCH] mount: parse default values correctly

[Steve Dickson]

Commit 88c22f92 converted the configfile.c routines
to use the parse_opt interfaces which broke how
default values from nfsmount.conf are managed.

Default values can not be added to the mount string
handed to the kernel. They must be interpreted into
the correct mount options then passed to the kernel.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1912877

Signed-off-by: Steve Dickson <steved@redhat.com>
---
 utils/mount/configfile.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/utils/mount/configfile.c b/utils/mount/configfile.c
index 7934f4f..e865998 100644
--- a/utils/mount/configfile.c
+++ b/utils/mount/configfile.c
@@ -277,8 +277,10 @@ conf_parse_mntopts(char *section, char *arg, struct mount_options *options)
 		}
 		if (buf[0] == '\0')
 			continue;
+		if (default_value(buf))
+			continue;
+
 		po_append(options, buf);
-		default_value(buf);
 	}
 	conf_free_list(list);
 }
-- 
2.29.2

Re: [PATCH] mount: parse default values correctly

[Steve Dickson]

On 1/6/21 1:40 PM, Steve Dickson wrote:
> Commit 88c22f92 converted the configfile.c routines
> to use the parse_opt interfaces which broke how
> default values from nfsmount.conf are managed.
> 
> Default values can not be added to the mount string
> handed to the kernel. They must be interpreted into
> the correct mount options then passed to the kernel.
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1912877
> 
> Signed-off-by: Steve Dickson <steved@redhat.com>
Committed... (tag: nfs-utils-2-5-3-rc4)

steved.
> ---
>  utils/mount/configfile.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/utils/mount/configfile.c b/utils/mount/configfile.c
> index 7934f4f..e865998 100644
> --- a/utils/mount/configfile.c
> +++ b/utils/mount/configfile.c
> @@ -277,8 +277,10 @@ conf_parse_mntopts(char *section, char *arg, struct mount_options *options)
>  		}
>  		if (buf[0] == '\0')
>  			continue;
> +		if (default_value(buf))
> +			continue;
> +
>  		po_append(options, buf);
> -		default_value(buf);
>  	}
>  	conf_free_list(list);
>  }
> 

Re: [PATCH] mount: parse default values correctly

[NeilBrown]

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On Wed, Jan 06 2021, Steve Dickson wrote:

> Commit 88c22f92 converted the configfile.c routines
> to use the parse_opt interfaces which broke how
> default values from nfsmount.conf are managed.
>
> Default values can not be added to the mount string
> handed to the kernel. They must be interpreted into
> the correct mount options then passed to the kernel.
>
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1912877
>
> Signed-off-by: Steve Dickson <steved@redhat.com>
> ---
>  utils/mount/configfile.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/utils/mount/configfile.c b/utils/mount/configfile.c
> index 7934f4f..e865998 100644
> --- a/utils/mount/configfile.c
> +++ b/utils/mount/configfile.c
> @@ -277,8 +277,10 @@ conf_parse_mntopts(char *section, char *arg, struct mount_options *options)
>  		}
>  		if (buf[0] == '\0')
>  			continue;
> +		if (default_value(buf))
> +			continue;
> +
>  		po_append(options, buf);
> -		default_value(buf);
>  	}
>  	conf_free_list(list);
>  }
> -- 
> 2.29.2

Hi,
 unfortunately this is incorrect.  As the referenced patch said:

    The default_value() call is now made as soon as the option has been
    parsed.  It is left on the options list so that new instances of the
    value are ignored.

 The new code doesn't leave it on the option list, so new instances are
 not ignored.

 conf_get_mntopts() processes options for the mount point, then options
 for the server, then global options.  If there is e.g. a defaultvers
 for both the mountpoint and as a global option, the global option will
 now not be ignored, so it takes precedence.

 The real problem as identified in the bugzilla discussion, is that
   	po_remove_all(options, "default");
 doesn't remove all the "default*" options as was the intent.  Clearly I
 never tested that.
 This is easily fixed with
 -	po_remove_all(options, "default");
 +	while (po_contains_prefix(options, "default", &ptr, 0) == PO_FOUND)
 +		po_remove_all(options, ptr);

 which I have tested :-)

 I'll follow up with a patch which reverts the incorrect fix, and adds
 this one.

Thanks,
NeilBrown


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[PATCH nfs-utils] mount: fix parsing of default options

[NeilBrown]

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A recent patch to change configfile.c to use parse_opt.c contained code
which was intended to remove all "default*" options from the list before
that could be passed to the kernel.  This code didn't work, so default*
options WERE passed to the kernel, and the kernel complained and failed
the mount attempt.

A more recent patch attempted to fix this by not including the
"default*" options in the option list at all.  This resulting in
global-default defaults over-riding per-mount or per-server defaults.

This patch reverse the "more recent" patch, and fixes the original patch
by providing correct code to remove all "default*" options before the
kernel can see them.

Fixes: 88c22f924f1b ("mount: convert configfile.c to use parse_opt.c")
Fixes: 8142542bda28 ("mount: parse default values correctly")
Signed-off-by: NeilBrown <neilb@suse.de>
---
 utils/mount/configfile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/utils/mount/configfile.c b/utils/mount/configfile.c
index e865998dd5a9..ab386d08b031 100644
--- a/utils/mount/configfile.c
+++ b/utils/mount/configfile.c
@@ -277,10 +277,9 @@ conf_parse_mntopts(char *section, char *arg, struct mount_options *options)
 		}
 		if (buf[0] == '\0')
 			continue;
-		if (default_value(buf))
-			continue;
 
 		po_append(options, buf);
+		default_value(buf);
 	}
 	conf_free_list(list);
 }
@@ -335,7 +334,8 @@ char *conf_get_mntopts(char *spec, char *mount_point,
 	 * Strip out defaults, which have already been handled,
 	 * then join the rest and return.
 	 */
-	po_remove_all(options, "default");
+	while (po_contains_prefix(options, "default", &ptr, 0) == PO_FOUND)
+		po_remove_all(options, ptr);
 
 	po_join(options, &mount_opts);
 	po_destroy(options);
-- 
2.30.0


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[PATCH nfs-utils v2] mount: fix parsing of default options

[NeilBrown]

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A recent patch to change configfile.c to use parse_opt.c contained code
which was intended to remove all "default*" options from the list before
that could be passed to the kernel.  This code didn't work, so default*
options WERE passed to the kernel, and the kernel complained and failed
the mount attempt.

A more recent patch attempted to fix this by not including the
"default*" options in the option list at all.  This resulting in
global-default defaults over-riding per-mount or per-server defaults.

This patch reverse the "more recent" patch, and fixes the original patch
by providing correct code to remove all "default*" options before the
kernel can see them.

Fixes: 88c22f924f1b ("mount: convert configfile.c to use parse_opt.c")
Fixes: 8142542bda28 ("mount: parse default values correctly")
Signed-off-by: NeilBrown <neilb@suse.de>
---

I realized that po_remove_all() could free 'ptr' and then compare it
against the next option, which would have undefined results.
So best to strdup and free it.


 utils/mount/configfile.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/utils/mount/configfile.c b/utils/mount/configfile.c
index e865998dd5a9..3d3684efa186 100644
--- a/utils/mount/configfile.c
+++ b/utils/mount/configfile.c
@@ -277,10 +277,9 @@ conf_parse_mntopts(char *section, char *arg, struct mount_options *options)
 		}
 		if (buf[0] == '\0')
 			continue;
-		if (default_value(buf))
-			continue;
 
 		po_append(options, buf);
+		default_value(buf);
 	}
 	conf_free_list(list);
 }
@@ -335,7 +334,11 @@ char *conf_get_mntopts(char *spec, char *mount_point,
 	 * Strip out defaults, which have already been handled,
 	 * then join the rest and return.
 	 */
-	po_remove_all(options, "default");
+	while (po_contains_prefix(options, "default", &ptr, 0) == PO_FOUND) {
+		ptr = strdup(ptr);
+		po_remove_all(options, ptr);
+		free(ptr);
+	}
 
 	po_join(options, &mount_opts);
 	po_destroy(options);
-- 
2.30.0


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Re: [PATCH nfs-utils v2] mount: fix parsing of default options

[Steve Dickson]

On 2/1/21 12:00 AM, NeilBrown wrote:
> 
> A recent patch to change configfile.c to use parse_opt.c contained code
> which was intended to remove all "default*" options from the list before
> that could be passed to the kernel.  This code didn't work, so default*
> options WERE passed to the kernel, and the kernel complained and failed
> the mount attempt.
> 
> A more recent patch attempted to fix this by not including the
> "default*" options in the option list at all.  This resulting in
> global-default defaults over-riding per-mount or per-server defaults.
> 
> This patch reverse the "more recent" patch, and fixes the original patch
> by providing correct code to remove all "default*" options before the
> kernel can see them.
> 
> Fixes: 88c22f924f1b ("mount: convert configfile.c to use parse_opt.c")
> Fixes: 8142542bda28 ("mount: parse default values correctly")
> Signed-off-by: NeilBrown <neilb@suse.de>
Committed.... (tag: nfs-utils-2-5-3-rc5)

steved.
> ---
> 
> I realized that po_remove_all() could free 'ptr' and then compare it
> against the next option, which would have undefined results.
> So best to strdup and free it.
> 
> 
>  utils/mount/configfile.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/utils/mount/configfile.c b/utils/mount/configfile.c
> index e865998dd5a9..3d3684efa186 100644
> --- a/utils/mount/configfile.c
> +++ b/utils/mount/configfile.c
> @@ -277,10 +277,9 @@ conf_parse_mntopts(char *section, char *arg, struct mount_options *options)
>  		}
>  		if (buf[0] == '\0')
>  			continue;
> -		if (default_value(buf))
> -			continue;
>  
>  		po_append(options, buf);
> +		default_value(buf);
>  	}
>  	conf_free_list(list);
>  }
> @@ -335,7 +334,11 @@ char *conf_get_mntopts(char *spec, char *mount_point,
>  	 * Strip out defaults, which have already been handled,
>  	 * then join the rest and return.
>  	 */
> -	po_remove_all(options, "default");
> +	while (po_contains_prefix(options, "default", &ptr, 0) == PO_FOUND) {
> +		ptr = strdup(ptr);
> +		po_remove_all(options, ptr);
> +		free(ptr);
> +	}
>  
>  	po_join(options, &mount_opts);
>  	po_destroy(options);
>