| Message ID | 20201014180209.49299-4-dgilbert@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | virtiofsd xattr name mappings | expand |
On Wed, Oct 14, 2020 at 07:02:07PM +0100, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Map xattr names coming from the server, i.e. the host filesystem; > currently this is only from listxattr. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > tools/virtiofsd/passthrough_ll.c | 89 ++++++++++++++++++++++++++++++++ > 1 file changed, 89 insertions(+) Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
On Wed, Oct 14, 2020 at 07:02:07PM +0100, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > Map xattr names coming from the server, i.e. the host filesystem; > currently this is only from listxattr. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > tools/virtiofsd/passthrough_ll.c | 89 ++++++++++++++++++++++++++++++++ > 1 file changed, 89 insertions(+) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 57ebe17ed6..8406a2ae86 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -2220,6 +2220,43 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, > } > } > > + /* Shouldn't get here - rules should have an END_* - check parse_xattrmap */ > + abort(); > +} > + > +/* > + * For use with listxattr where the server fs gives us a name and we may need > + * to sanitize this for the client. > + * Returns a pointer to the result in *out_name > + * This is always the original string or the current string with some prefix > + * removed; no reallocation is done. > + * Returns 0 on success > + * Can return -ENODATA to indicate the name should be dropped from the list. > + */ > +static int xattr_map_server(const struct lo_data *lo, const char *server_name, > + const char **out_name) > +{ > + const XattrMapEntry *cur_entry; > + const char *end; > + > + for (cur_entry = lo->xattr_map_list; ; cur_entry++) { > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > + (strstart(server_name, cur_entry->prepend, &end))) { > + if (cur_entry->flags & XATTR_MAP_FLAG_END_BAD) { > + return -ENODATA; > + } > + if (cur_entry->flags & XATTR_MAP_FLAG_END_OK) { > + *out_name = server_name; > + return 0; > + } > + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { > + /* Remove prefix */ > + *out_name = end; > + return 0; > + } > + } > + } > + > /* Shouldn't get here - rules should have an END_* */ > abort(); I am wondering why to put that restriction. If none of the rules match, can't we just return as nothing has to be done. > } > @@ -2378,8 +2415,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > if (ret == 0) { > goto out; > } > + > + if (lo->xattr_map_list) { > + /* > + * Map the names back, some attributes might be dropped, > + * some shortened, but not increased, so we shouldn't > + * run out of room. > + */ > + size_t out_index, in_index; > + out_index = 0; > + in_index = 0; > + while (in_index < ret) { > + const char *map_out; > + char *in_ptr = value + in_index; > + /* Length of current attribute name */ > + size_t in_len = strlen(value + in_index) + 1; > + > + int mapret = xattr_map_server(lo, in_ptr, &map_out); > + if (mapret != -ENODATA && mapret != 0) { > + /* Shouldn't happen */ > + saverr = -mapret; > + goto out; > + } > + if (mapret == 0) { > + /* Either unchanged, or truncated */ > + size_t out_len; > + if (map_out != in_ptr) { > + /* +1 copies the NIL */ > + out_len = strlen(map_out) + 1; > + } else { > + /* No change */ > + out_len = in_len; > + } > + /* > + * Move result along, may still be needed for an unchanged > + * entry if a previous entry was changed. > + */ > + memmove(value + out_index, map_out, out_len); > + > + out_index += out_len; > + } > + in_index += in_len; > + } > + ret = out_index; > + if (ret == 0) { > + goto out; > + } > + } > fuse_reply_buf(req, value, ret); > } else { > + /* > + * xattrmap only ever shortens the result, > + * so we don't need to do anything clever with the > + * allocation length here. > + */ > fuse_reply_xattr(req, ret); Hmmm.., so this code returns the length of buffer which will fit xattrs. So we will will changing the semantics a bit. Instead of returning the exact size of buffer needed, we will be returning max size. I hope its not a problem. Fixing it will be too expensive I guess. Thanks Vivek
* Vivek Goyal (vgoyal@redhat.com) wrote: > On Wed, Oct 14, 2020 at 07:02:07PM +0100, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > > > Map xattr names coming from the server, i.e. the host filesystem; > > currently this is only from listxattr. > > > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > --- > > tools/virtiofsd/passthrough_ll.c | 89 ++++++++++++++++++++++++++++++++ > > 1 file changed, 89 insertions(+) > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 57ebe17ed6..8406a2ae86 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -2220,6 +2220,43 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, > > } > > } > > > > + /* Shouldn't get here - rules should have an END_* - check parse_xattrmap */ > > + abort(); > > +} > > + > > +/* > > + * For use with listxattr where the server fs gives us a name and we may need > > + * to sanitize this for the client. > > + * Returns a pointer to the result in *out_name > > + * This is always the original string or the current string with some prefix > > + * removed; no reallocation is done. > > + * Returns 0 on success > > + * Can return -ENODATA to indicate the name should be dropped from the list. > > + */ > > +static int xattr_map_server(const struct lo_data *lo, const char *server_name, > > + const char **out_name) > > +{ > > + const XattrMapEntry *cur_entry; > > + const char *end; > > + > > + for (cur_entry = lo->xattr_map_list; ; cur_entry++) { > > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > > + (strstart(server_name, cur_entry->prepend, &end))) { > > + if (cur_entry->flags & XATTR_MAP_FLAG_END_BAD) { > > + return -ENODATA; > > + } > > + if (cur_entry->flags & XATTR_MAP_FLAG_END_OK) { > > + *out_name = server_name; > > + return 0; > > + } > > + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { > > + /* Remove prefix */ > > + *out_name = end; > > + return 0; > > + } > > + } > > + } > > + > > /* Shouldn't get here - rules should have an END_* */ > > abort(); > > I am wondering why to put that restriction. If none of the rules match, > can't we just return as nothing has to be done. I always add a terminator in the parse as either a bad/ok, and was just enforcing it - but I've changed it to a return -ENODATA that's probably safer than the abort(). > > } > > @@ -2378,8 +2415,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > > if (ret == 0) { > > goto out; > > } > > + > > + if (lo->xattr_map_list) { > > + /* > > + * Map the names back, some attributes might be dropped, > > + * some shortened, but not increased, so we shouldn't > > + * run out of room. > > + */ > > + size_t out_index, in_index; > > + out_index = 0; > > + in_index = 0; > > + while (in_index < ret) { > > + const char *map_out; > > + char *in_ptr = value + in_index; > > + /* Length of current attribute name */ > > + size_t in_len = strlen(value + in_index) + 1; > > + > > + int mapret = xattr_map_server(lo, in_ptr, &map_out); > > + if (mapret != -ENODATA && mapret != 0) { > > + /* Shouldn't happen */ > > + saverr = -mapret; > > + goto out; > > + } > > + if (mapret == 0) { > > + /* Either unchanged, or truncated */ > > + size_t out_len; > > + if (map_out != in_ptr) { > > + /* +1 copies the NIL */ > > + out_len = strlen(map_out) + 1; > > + } else { > > + /* No change */ > > + out_len = in_len; > > + } > > + /* > > + * Move result along, may still be needed for an unchanged > > + * entry if a previous entry was changed. > > + */ > > + memmove(value + out_index, map_out, out_len); > > + > > + out_index += out_len; > > + } > > + in_index += in_len; > > + } > > + ret = out_index; > > + if (ret == 0) { > > + goto out; > > + } > > + } > > fuse_reply_buf(req, value, ret); > > } else { > > + /* > > + * xattrmap only ever shortens the result, > > + * so we don't need to do anything clever with the > > + * allocation length here. > > + */ > > fuse_reply_xattr(req, ret); > > Hmmm.., so this code returns the length of buffer which will fit xattrs. > So we will will changing the semantics a bit. Instead of returning > the exact size of buffer needed, we will be returning max size. I hope > its not a problem. Fixing it will be too expensive I guess. Right, although the semantics are fuzzy anyway since someone can come along and add/remove an xattr between the listxattr calls. Dave > Thanks > Vivek -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 57ebe17ed6..8406a2ae86 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2220,6 +2220,43 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, } } + /* Shouldn't get here - rules should have an END_* - check parse_xattrmap */ + abort(); +} + +/* + * For use with listxattr where the server fs gives us a name and we may need + * to sanitize this for the client. + * Returns a pointer to the result in *out_name + * This is always the original string or the current string with some prefix + * removed; no reallocation is done. + * Returns 0 on success + * Can return -ENODATA to indicate the name should be dropped from the list. + */ +static int xattr_map_server(const struct lo_data *lo, const char *server_name, + const char **out_name) +{ + const XattrMapEntry *cur_entry; + const char *end; + + for (cur_entry = lo->xattr_map_list; ; cur_entry++) { + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && + (strstart(server_name, cur_entry->prepend, &end))) { + if (cur_entry->flags & XATTR_MAP_FLAG_END_BAD) { + return -ENODATA; + } + if (cur_entry->flags & XATTR_MAP_FLAG_END_OK) { + *out_name = server_name; + return 0; + } + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { + /* Remove prefix */ + *out_name = end; + return 0; + } + } + } + /* Shouldn't get here - rules should have an END_* */ abort(); } @@ -2378,8 +2415,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) if (ret == 0) { goto out; } + + if (lo->xattr_map_list) { + /* + * Map the names back, some attributes might be dropped, + * some shortened, but not increased, so we shouldn't + * run out of room. + */ + size_t out_index, in_index; + out_index = 0; + in_index = 0; + while (in_index < ret) { + const char *map_out; + char *in_ptr = value + in_index; + /* Length of current attribute name */ + size_t in_len = strlen(value + in_index) + 1; + + int mapret = xattr_map_server(lo, in_ptr, &map_out); + if (mapret != -ENODATA && mapret != 0) { + /* Shouldn't happen */ + saverr = -mapret; + goto out; + } + if (mapret == 0) { + /* Either unchanged, or truncated */ + size_t out_len; + if (map_out != in_ptr) { + /* +1 copies the NIL */ + out_len = strlen(map_out) + 1; + } else { + /* No change */ + out_len = in_len; + } + /* + * Move result along, may still be needed for an unchanged + * entry if a previous entry was changed. + */ + memmove(value + out_index, map_out, out_len); + + out_index += out_len; + } + in_index += in_len; + } + ret = out_index; + if (ret == 0) { + goto out; + } + } fuse_reply_buf(req, value, ret); } else { + /* + * xattrmap only ever shortens the result, + * so we don't need to do anything clever with the + * allocation length here. + */ fuse_reply_xattr(req, ret); } out_free: