| Message ID | 20190619123019.30032-5-mszeredi@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/13] vfs: verify param type in vfs_parse_sb_flag() | expand |
On Wed, 2019-06-19 at 14:30 +0200, Miklos Szeredi wrote: > While this is a standard option as documented in mount(8), it is ignored by > most filesystems. So reject, unless filesystem explicitly wants to handle > it. > > The exception is unconverted filesystems, where it is unknown if the > filesystem handles this or not. > > Any implementation, such as mount(8) that needs to parse this option > without failing should simply ignore the return value from fsconfig(). In theory this is fine but every time someone has attempted to change the handling of this in the past autofs has had problems so I'm a bit wary of the change. It was originally meant to tell the file system to ignore invalid options such as could be found in automount maps that are used with multiple OS implementations that have differences in their options. That was, IIRC, primarily NFS although NFS should handle most (if not all of those) cases these days. Nevertheless I'm a bit nervous about it, ;) > > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> > --- > fs/fs_context.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/fs_context.c b/fs/fs_context.c > index 49636e541293..c26b353aa858 100644 > --- a/fs/fs_context.c > +++ b/fs/fs_context.c > @@ -51,7 +51,6 @@ static const struct constant_table common_clear_sb_flag[] = > { > { "nolazytime", SB_LAZYTIME }, > { "nomand", SB_MANDLOCK }, > { "rw", SB_RDONLY }, > - { "silent", SB_SILENT }, > }; > > /* > @@ -535,6 +534,9 @@ static int legacy_parse_param(struct fs_context *fc, > struct fs_parameter *param) > if (ret != -ENOPARAM) > return ret; > > + if (strcmp(param->key, "silent") == 0) > + fc->sb_flags |= SB_SILENT; > + > if (strcmp(param->key, "source") == 0) { > if (param->type != fs_value_is_string) > return invalf(fc, "VFS: Legacy: Non-string source");
On Thu, Jun 20, 2019 at 6:40 AM Ian Kent <raven@themaw.net> wrote: > > On Wed, 2019-06-19 at 14:30 +0200, Miklos Szeredi wrote: > > While this is a standard option as documented in mount(8), it is ignored by > > most filesystems. So reject, unless filesystem explicitly wants to handle > > it. > > > > The exception is unconverted filesystems, where it is unknown if the > > filesystem handles this or not. > > > > Any implementation, such as mount(8) that needs to parse this option > > without failing should simply ignore the return value from fsconfig(). > > In theory this is fine but every time someone has attempted > to change the handling of this in the past autofs has had > problems so I'm a bit wary of the change. > > It was originally meant to tell the file system to ignore > invalid options such as could be found in automount maps that > are used with multiple OS implementations that have differences > in their options. > > That was, IIRC, primarily NFS although NFS should handle most > (if not all of those) cases these days. > > Nevertheless I'm a bit nervous about it, ;) What I'm saying is that with a new interface the rules need not follow the rules of the old interface, because at the start no one is using the new interface, so no chance of breaking anything. Yes, there's a chance of making the interface difficult to use, but I don't think this is one of those things. For one, "silent" should not be needed on the new interface at all, because error messages relating to the setup of the filesystem can be redirected to a log buffer dedicated to the setup instance, effectively enabling silent operation by default. Thanks., Miklos
Miklos Szeredi <mszeredi@redhat.com> wrote: > What I'm saying is that with a new interface the rules need not follow > the rules of the old interface, because at the start no one is using > the new interface, so no chance of breaking anything. Er. No. That's not true, since the old interface comes through the new one. David
On Mon, Jun 24, 2019 at 12:36 PM David Howells <dhowells@redhat.com> wrote: > > Miklos Szeredi <mszeredi@redhat.com> wrote: > > > What I'm saying is that with a new interface the rules need not follow > > the rules of the old interface, because at the start no one is using > > the new interface, so no chance of breaking anything. > > Er. No. That's not true, since the old interface comes through the new one. No, old interface sets SB_* directly from arg 4 of mount(2) and not via parsing arg 5. Thanks, Miklos
On Mon, Jun 24, 2019 at 12:44 PM Miklos Szeredi <mszeredi@redhat.com> wrote: > > On Mon, Jun 24, 2019 at 12:36 PM David Howells <dhowells@redhat.com> wrote: > > > > Miklos Szeredi <mszeredi@redhat.com> wrote: > > > > > What I'm saying is that with a new interface the rules need not follow > > > the rules of the old interface, because at the start no one is using > > > the new interface, so no chance of breaking anything. > > > > Er. No. That's not true, since the old interface comes through the new one. > > No, old interface sets SB_* directly from arg 4 of mount(2) and not > via parsing arg 5. See also 9p mess up of "posixacl" handling *on the old interface* due to exactly because the internal API doesn't differentiate between options coming from the old interface and ones coming from the new. So you are right that there's breakage, but it's due to the fact that common code parses anything, and not because it doesn't. Thanks, Miklos
diff --git a/fs/fs_context.c b/fs/fs_context.c index 49636e541293..c26b353aa858 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -51,7 +51,6 @@ static const struct constant_table common_clear_sb_flag[] = { { "nolazytime", SB_LAZYTIME }, { "nomand", SB_MANDLOCK }, { "rw", SB_RDONLY }, - { "silent", SB_SILENT }, }; /* @@ -535,6 +534,9 @@ static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param) if (ret != -ENOPARAM) return ret; + if (strcmp(param->key, "silent") == 0) + fc->sb_flags |= SB_SILENT; + if (strcmp(param->key, "source") == 0) { if (param->type != fs_value_is_string) return invalf(fc, "VFS: Legacy: Non-string source");
While this is a standard option as documented in mount(8), it is ignored by most filesystems. So reject, unless filesystem explicitly wants to handle it. The exception is unconverted filesystems, where it is unknown if the filesystem handles this or not. Any implementation, such as mount(8) that needs to parse this option without failing should simply ignore the return value from fsconfig(). Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> --- fs/fs_context.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)