On January 2, 2017 at 5:58 PM Michal Soltys <soltys at ziu.info> wrote:>> >> >> Hi, >> >> Are configurations (with separate formats per namespace) - such as ... >> >> namespace { >> type = shared >> list = children >> inbox = no >> separator = / >> subscriptions = no >> prefix = shared1/%%n/ >> location = maildir:/var/mail1/%%n/ >> } >> >> namespace { >> type = shared >> list = children >> inbox = no >> separator = / >> subscriptions = no >> prefix = shared2/%%n/ >> location = mdbox:/var/mail2/%%n/ >> } >> >> With separate userdbs serving part of the users with maildirs in /var/mail1/ >> and the other part with mdboxes in /var/mail2 >> >> ... valid in dovecot ? >> >> To be more precise: >> >> 1) Is current version dovecot expected to work with configuration as above ? >> E.g. if some user's mail location returned from userdb doesn't match >> location/format from one of the above namespaces - would it be ignored for it >> ? A very old version of dovecot I could check quickly (2.1.7) was segfaulting >> (imap processes) all the time with this kind of config. While I'll be >> upgrading it and the whole system to modern versions, I'm wondering if this >> kind of thing is formally allowed at all. >> >> An interesting variation of the above setup I tested - with the second >> namespace "un-variabled" and pointing to single user (with matching >> passwd-file returning that user) managed to work somehow - but the user itself >> was still created on the fly for the 1st namespace - having just a directory >> with empty dovecot-acl-list file. This essentially seemed to have worked like >> a typical public profile (shared acl db didn't seem to be used either) >>> On 2017-01-02 19:21, Aki Tuomi wrote: >> Yeah, that's valid configuration. As long as they have unique prefix. >> >> Aki >>Well, I retested it under 2.2.27 - and the behaviour is essentially the same (segfaults). Below is the simplified configuration under which it can be observed with 2 passwd-files (each with 1 user, passwords removed to save space) passwd-file local-mdbox: nmm:{SHA256}<cut>:::nmm:/var/mail2/nmm::userdb_mail=mdbox:/var/mail2/nmm userdb_home=/var/mail2/nmm passwd-file local-maildir: msl:{SHA256}<cut>:::msl:/var/mail/msl::userdb_mail=maildir:/var/mail/msl userdb_home=/var/mail/msl Both of the accounts have some mails/subfolders, nmm is sharing some of its contents to msl. doveconf -n (note thare are some leftovers from old configuration - particularly weird last/first uids and mail_uid using dovecot user - but those are not relevant to the issue): # 2.2.27 (c0f36b0): /etc/dovecot/dovecot.conf # OS: Linux 4.8.13-1-ARCH x86_64 ext4 auth_debug = yes auth_mechanisms = plain login disable_plaintext_auth = no first_valid_gid = 8 first_valid_uid = 105 last_valid_gid = 8 last_valid_uid = 105 listen = * log_path = /var/log/dovecot.log mail_access_groups = mail mail_debug = yes mail_gid = mail mail_location = maildir:/var/mail/%n mail_plugins = acl mail_uid = dovecot namespace { inbox = yes location = prefix = separator = / type = private } namespace share1 { inbox = no list = children location = maildir:%%h prefix = shared1/%%n/ separator = / subscriptions = no type = shared } namespace share2 { inbox = no list = children location = mdbox:%%h prefix = shared2/%%n/ separator = / subscriptions = no type = shared } passdb { args = username_format=%n /etc/dovecot/local-maildir default_fields = userdb_uid=dovecot userdb_gid=mail driver = passwd-file } passdb { args = username_format=%n /etc/dovecot/local-mdbox default_fields = userdb_uid=dovecot userdb_gid=mail driver = passwd-file } plugin { acl = vfile acl_shared_dict = file:/var/mail/shared-database/shared-mailboxes.db } protocols = imap service auth { unix_listener auth-userdb { group = mail mode = 0660 user = dovecot } user = dovecot } service imap-login { inet_listener imap { port = 0 } user = dovecot } service imap { executable = /usr/lib/dovecot/imap } userdb { driver = prefetch } userdb { args = username_format=%n /etc/dovecot/local-maildir default_fields = uid=dovecot gid=mail driver = passwd-file } userdb { args = username_format=%n /etc/dovecot/local-mdbox default_fields = uid=dovecot gid=mail driver = passwd-file } protocol imap { mail_max_userip_connections = 100 mail_plugins = acl imap_acl } With the configuration and 2 passwd-files as above, all imap processes (when logged as user msl) constantly crash with segfaults. Replacing %%h by template such as /var/mail/%%n (as in my initial report) behaves the same way. Now - IF share1 namespace is commented out or removed - everything works fine (and msl sees content shared by nmm under shared2/nmm/ ). Similarly - if only one shared namespace uses variables and the other points directly to some user - no crashes then. Any ideas ? I can get systraces/cores (though the latter without debug symbols - but I can recompile if need be).
Michal Soltys
2017-Jan-10 19:19 UTC
multiple shared/mail format namespaces (segv identified + patch)
I think I've found the reason behind those crashes as in the configuration
posted in the earlier mail.
First the full backtrace:
Message: Process 13965 (imap) of user 105 dumped core.
Stack trace of thread 13965:
#0 0x00007fbdaa15929a __strcmp_sse2_unaligned (libc.so.6)
#1 0x00007fbdaa820c50 mail_storage_match_class
(libdovecot-storage.so.0)
#2 0x00007fbdaa820cbf mail_storage_find
(libdovecot-storage.so.0)
#3 0x00007fbdaa82103d mail_storage_create_full
(libdovecot-storage.so.0)
#4 0x00007fbdaa8212c2 mail_storage_create
(libdovecot-storage.so.0)
#5 0x00007fbdaa816cdc mail_namespaces_init_add
(libdovecot-storage.so.0)
#6 0x00007fbdaa817694 mail_namespaces_init
(libdovecot-storage.so.0)
#7 0x00007fbdaa82a4cd mail_storage_service_init_post
(libdovecot-storage.so.0)
#8 0x00007fbdaa82c266 mail_storage_service_next_real
(libdovecot-storage.so.0)
#9 0x00007fbdaa82c321 mail_storage_service_next
(libdovecot-storage.so.0)
#10 0x00007fbdaa82c49a mail_storage_service_lookup_next
(libdovecot-storage.so.0)
#11 0x00000000004314f0 client_create_from_input (imap)
#12 0x0000000000431968 login_client_connected (imap)
#13 0x00007fbdaa49b1c1 master_login_auth_finish
(libdovecot.so.0)
#14 0x00007fbdaa49baca master_login_auth_callback
(libdovecot.so.0)
#15 0x00007fbdaa49cae9 master_login_auth_input_user
(libdovecot.so.0)
#16 0x00007fbdaa49cfb1 master_login_auth_input (libdovecot.so.0)
#17 0x00007fbdaa54a545 io_loop_call_io (libdovecot.so.0)
#18 0x00007fbdaa54ce68 io_loop_handler_run_internal
(libdovecot.so.0)
#19 0x00007fbdaa54a726 io_loop_handler_run (libdovecot.so.0)
#20 0x00007fbdaa54a649 io_loop_run (libdovecot.so.0)
#21 0x00007fbdaa49ee3b master_service_run (libdovecot.so.0)
#22 0x0000000000431efb main (imap)
#23 0x00007fbdaa0ea291 __libc_start_main (libc.so.6)
#24 0x000000000040c6da _start (imap)
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Reading symbols from /usr/lib/dovecot/imap...done.
[New LWP 13965]
Core was generated by `dovecot/imap'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007fbdaa15929a in __strcmp_sse2_unaligned () from /usr/lib/libc.so.6
(gdb) up
#1 0x00007fbdaa820c50 in mail_storage_match_class (storage=0xdc5800,
storage_class=0x7fbdaab715c0 <shared_storage>, set=0x7fff217d6030) at
mail-storage.c:285
285 strcmp(storage->unique_root_dir,
(gdb) print storage->unique_root_dir
$1 = 0x0
(gdb)
So the first argument passed to strcmp() was NULL.
The offending part of code is:
if ((storage->class_flags & MAIL_STORAGE_CLASS_FLAG_UNIQUE_ROOT) != 0
&&
strcmp(storage->unique_root_dir,
(set->root_dir != NULL ? set->root_dir : "")) != 0)
return FALSE;
The 2nd argument is sanitized explicitly, but the first is not - and apparently
it can
be NULL as well. Adding same check to the 1st argument stopped segfaults and
both
shared namespaces seemed to be working correctly - so user 'msl' could
see/subscribe
shared folders from user 'nnm' and vice versa (both mailboxes being of
different format).
While this was enough here, something else might be needed to make it fully
correct
(the original strcmp() invocation would suggest that the 1st argument should
never be NULL).
Michal Soltys
2017-Jan-10 19:58 UTC
[PATCH] mail-storage.c: check against NULL address in strcmp() invocation
Configurations with multiple shared namespaces can trigger a bug where the first argument of strcmp() invocation is NULL. This patch adds an explicit check, analogously to how the second argument is sanitized. --- src/lib-storage/mail-storage.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/lib-storage/mail-storage.c b/src/lib-storage/mail-storage.c index 1d9b1bf..3d9f5dc 100644 --- a/src/lib-storage/mail-storage.c +++ b/src/lib-storage/mail-storage.c @@ -282,7 +282,7 @@ mail_storage_match_class(struct mail_storage *storage, return FALSE; if ((storage->class_flags & MAIL_STORAGE_CLASS_FLAG_UNIQUE_ROOT) != 0 && - strcmp(storage->unique_root_dir, + strcmp((storage->unique_root_dir != NULL ? storage->unique_root_dir : ""), (set->root_dir != NULL ? set->root_dir : "")) != 0) return FALSE; -- 2.1.3
Possibly Parallel Threads
- multiple shared/mail format namespaces (segv identified + patch)
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- [LLVMdev] Bug in optimization pass related to strcmp and big endian back-ends
- [LLVMdev] Bug in optimization pass related to strcmp and bigendian back-ends
- [PATCH] mail-storage.c: check against NULL address in strcmp() invocation