| Message ID | 20200827153657.111098-6-dgilbert@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | virtiofsd xattr name mappings | expand |
On 2020-08-27 at 17:36 CEST, 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 | 88 ++++++++++++++++++++++++++++++++ > 1 file changed, 88 insertions(+) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 9b9c8f3ab1..7cd99186f7 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -2188,6 +2188,42 @@ static int xattr_map_client(const char *client_name, char **out_name) > 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 char *server_name, const char **out_name) > +{ > + const XattrMapEntry *cur_entry; > + for (cur_entry = xattr_map_list; ; cur_entry++) { > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > + (!strncmp(cur_entry->prepend, > + server_name, > + strlen(cur_entry->prepend)))) { Might be slightly clearer (and possibly faster) as strstart(cur_entry->prepend, server_name, &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 = server_name + strlen(cur_entry->prepend); With the above, that would be *out_name = end; > + return 0; > + } > + } > + } > + > + /* Shouldn't get here - rules should have an END_* */ You probably want to point the finger back to parse_xattrmap() in the comment? > + abort(); > +} > + > static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, > size_t size) > { > @@ -2342,8 +2378,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > if (ret == 0) { > goto out; > } > + > + if (lo->xattrmap) { If you put the "XattrMapEntry" pointer in lo, then you would probably test that. > + /* > + * 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(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. > + */ I don't understand the comment above. We are in the !lo->xattrmap) case, no? > fuse_reply_xattr(req, ret); > } > out_free: -- Cheers, Christophe de Dinechin (IRC c3d)
On 2020-08-27 at 17:36 CEST, 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 | 88 ++++++++++++++++++++++++++++++++ > 1 file changed, 88 insertions(+) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 9b9c8f3ab1..7cd99186f7 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -2188,6 +2188,42 @@ static int xattr_map_client(const char *client_name, char **out_name) > 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 char *server_name, const char **out_name) > +{ > + const XattrMapEntry *cur_entry; > + for (cur_entry = xattr_map_list; ; cur_entry++) { > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > + (!strncmp(cur_entry->prepend, > + server_name, > + strlen(cur_entry->prepend)))) { Overall, the same remarks apply as for the client side. > + 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 = server_name + strlen(cur_entry->prepend); > + return 0; > + } > + } > + } > + > + /* Shouldn't get here - rules should have an END_* */ > + abort(); > +} > + > static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, > size_t size) > { > @@ -2342,8 +2378,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > if (ret == 0) { > goto out; > } > + > + if (lo->xattrmap) { > + /* > + * 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(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: -- Cheers, Christophe de Dinechin (IRC c3d)
* Christophe de Dinechin (dinechin@redhat.com) wrote: > > On 2020-08-27 at 17:36 CEST, 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 | 88 ++++++++++++++++++++++++++++++++ > > 1 file changed, 88 insertions(+) > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 9b9c8f3ab1..7cd99186f7 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -2188,6 +2188,42 @@ static int xattr_map_client(const char *client_name, char **out_name) > > 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 char *server_name, const char **out_name) > > > +{ > > + const XattrMapEntry *cur_entry; > > + for (cur_entry = xattr_map_list; ; cur_entry++) { > > + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && > > + (!strncmp(cur_entry->prepend, > > + server_name, > > + strlen(cur_entry->prepend)))) { > > Might be slightly clearer (and possibly faster) as > > strstart(cur_entry->prepend, server_name, &end) I think this is actually, strstart(server_name, cur_entry->prepend, &end) because I think strstart writes the offset into the 1st string into &end expecting the 2nd string to be the thing to test for. Agreed? > > + 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 = server_name + strlen(cur_entry->prepend); > > With the above, that would be > > *out_name = end; OK. > > > + return 0; > > + } > > + } > > + } > > + > > + /* Shouldn't get here - rules should have an END_* */ > > You probably want to point the finger back to parse_xattrmap() in the comment? Done. > > + abort(); > > > +} > > + > > static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, > > size_t size) > > { > > @@ -2342,8 +2378,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) > > if (ret == 0) { > > goto out; > > } > > + > > + if (lo->xattrmap) { > > If you put the "XattrMapEntry" pointer in lo, then you would probably test that. Done > > > + /* > > + * 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(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. > > + */ > > I don't understand the comment above. We are in the !lo->xattrmap) case, no? No, we're in the else for if (size) { for the case where the caller is trying not to actually get a list of the attributes, but to get a guess of the size of storage needed. Dave > > fuse_reply_xattr(req, ret); > > } > > out_free: > > > -- > Cheers, > Christophe de Dinechin (IRC c3d)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 9b9c8f3ab1..7cd99186f7 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2188,6 +2188,42 @@ static int xattr_map_client(const char *client_name, char **out_name) 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 char *server_name, const char **out_name) +{ + const XattrMapEntry *cur_entry; + for (cur_entry = xattr_map_list; ; cur_entry++) { + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && + (!strncmp(cur_entry->prepend, + server_name, + strlen(cur_entry->prepend)))) { + 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 = server_name + strlen(cur_entry->prepend); + return 0; + } + } + } + + /* Shouldn't get here - rules should have an END_* */ + abort(); +} + static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, size_t size) { @@ -2342,8 +2378,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) if (ret == 0) { goto out; } + + if (lo->xattrmap) { + /* + * 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(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: