Hi,

I get the following message each time I try to access a mailbox.

dovecot: [ID 684838 mail.error] child 27041 (imap) killed with signal 11

Using dovecot 1.0-test32 under Solaris 9.

Using truss I get the following lines:

27041: read(0, " 2 s e l e c t " I N".., 4096) = 18 27041: open64("/var/mail/toto", O_RDWR|O_CREAT|O_EXCL, 0660) Err#17 EEXIST 27041: time() = 1092672589 27041: open64("", O_RDWR) Err#14 EFAULT 27041: Incurred fault #6, FLTBOUNDS %pc = 0xFF1B347C 27041: siginfo: SIGSEGV SEGV_MAPERR addr=0x00000000 27041: Received signal #11, SIGSEGV [default] 27041: siginfo: SIGSEGV SEGV_MAPERR addr=0x00000000

I attached the complete result of the truss command and my configuration file.

Any idea what is the problem ?

Cheers,

Yann

Dovecot 1.0 configuration file

'#' character and everything after it is treated as comments. Extra spaces

and tabs are ignored. If you want to use either of these explicitly, put the

value inside quotes, eg.: key = "# char and trailing whitespace "

Default values are shown after each value, it's not required to uncomment

any of the lines. Exception to this are paths, they're just examples

with real defaults being based on configure options. The paths listed here

are for configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var

--with-ssldir=/etc/ssl

Base directory where to store runtime data.

base_dir = /var/run/dovecot/

Protocols we want to be serving:

imap imaps pop3 pop3s

protocols = imap

IP or host address where to listen in for connections. It's not currently

possible to specify multiple addresses. "*" listens in all IPv4 interfaces.

"[::]" listens in all IPv6 interfaces, but may also listen in all IPv4

interfaces depending on the operating system. You can specify ports with

"host:port", although with multiple protocols you probably want to move this

setting inside protocol imap/pop3 { ... } section, so you can specify

different ports for IMAP/POP3.

#listen = *

IP or host address where to listen in for SSL connections. Defaults

to above if not specified.

#ssl_listen =

Disable SSL/TLS support.

ssl_disable = yes

PEM encoded X.509 SSL/TLS certificate and private key. They're opened before

dropping root privileges, so keep the key file unreadable by anyone but

root. Included doc/mkcert.sh can be used to easily generate self-signed

certificate, just make sure to update the domains in dovecot-openssl.cnf

ssl_cert_file = /usr/local/public/ssl/certs/imapd.pem ssl_key_file = /usr/local/public/ssl/certs/imapd.pem

File containing trusted SSL certificate authorities. Usually not needed.

#ssl_ca_file =

Request client to send a certificate.

#ssl_verify_client_cert = no

SSL parameter file. Master process generates this file for login processes.

It contains Diffie Hellman and RSA parameters.

#ssl_parameters_file = /var/run/dovecot/ssl-parameters.dat

How often to regenerate the SSL parameters file. Generation is quite CPU

intensive operation. The value is in hours, 0 disables regeneration

entirely.

#ssl_parameters_regenerate = 24

SSL ciphers to use

#ssl_cipher_list = all:!low

Disable LOGIN command and all other plaintext authentications unless

SSL/TLS is used (LOGINDISABLED capability). Note that 127.*.*.* and

IPv6 ::1 addresses are considered secure, this setting has no effect if

you connect from those addresses.

disable_plaintext_auth = no

Use this logfile instead of syslog(). /dev/stderr can be used if you want to

use stderr for logging (ONLY /dev/stderr - otherwise it is closed).

#log_path =

For informational messages, use this logfile instead of the default

#info_log_path =

Prefix for each line written to log file. % codes are in strftime(3)

format.

#log_timestamp = "%b %d %H:%M:%S "

Login processes

Directory where authentication process places authentication UNIX sockets

which login needs to be able to connect to. The sockets are created when

running as root, so you don't have to worry about permissions. Note that

everything in this directory is deleted when Dovecot is started.

#login_dir = /var/run/dovecot/login

chroot login process to the login_dir. Only reason not to do this is if you

wish to run the whole Dovecot without roots.

login_chroot = no

User to use for the login process. Create a completely new user for this,

and don't use it anywhere else. The user must also belong to a group where

only it has access, it's used to control access for authentication process.

#login_user = dovecot

Set max. process size in megabytes. If you don't use

login_process_per_connection you might need to grow this.

#login_process_size = 32

Should each login be processed in it's own process (yes), or should one

login process be allowed to process multiple connections (no)? Yes is more

secure, espcially with SSL/TLS enabled. No is faster since there's no need

to create processes all the time.

#login_process_per_connection = yes

Number of login processes to create. If login_process_per_user is

yes, this is the number of extra processes waiting for users to log in.

#login_processes_count = 3

Maximum number of extra login processes to create. The extra process count

usually stays at login_processes_count, but when multiple users start logging

in at the same time more extra processes are created. To prevent fork-bombing

we check only once in a second if new processes should be created - if all

of them are used at the time, we double their amount until limit set by this

setting is reached. This setting is used only if login_process_per_use is yes.

#login_max_processes_count = 128

Maximum number of connections allowed in login state. When this limit is

reached, the oldest connections are dropped. If login_process_per_user

is no, this is a per-process value, so the absolute maximum number of users

logging in actually login_processes_count * max_logging_users.

#login_max_logging_users = 256

Mail processes

Maximum number of running mail processes. When this limit is reached,

new users aren't allowed to log in.

#max_mail_processes = 1024

Show more verbose process titles (in ps). Currently shows user name and

IP address. Useful for seeing who are actually using the IMAP processes

(eg. shared mailboxes or if same uid is used for multiple accounts).

#verbose_proctitle = no

Show protocol level SSL errors.

#verbose_ssl = no

Valid UID range for users, defaults to 500 and above. This is mostly

to make sure that users can't log in as daemons or other system users.

Note that denying root logins is hardcoded to dovecot binary and can't

be done even if first_valid_uid is set to 0.

first_valid_uid = 200 last_valid_uid = 0

Valid GID range for users, defaults to non-root/wheel. Users having

non-valid GID as primary group ID aren't allowed to log in. If user

belongs to supplementary groups with non-valid GIDs, those groups are

not set.

#first_valid_gid = 1 #last_valid_gid = 0

Grant access to these extra groups for mail processes. Typical use would be

to give "mail" group write access to /var/mail to be able to create dotlocks.

#mail_extra_groups =

':' separated list of directories under which chrooting is allowed for mail

processes (ie. /var/mail will allow chrooting to /var/mail/foo/bar too).

This setting doesn't affect login_chroot or auth_chroot variables.

WARNING: Never add directories here which local users can modify, that

may lead to root exploit. Usually this should be done only if you don't

allow shell access for users. See doc/configuration.txt for more information.

#valid_chroot_dirs =

Default chroot directory for mail processes. This can be overridden by

giving /./ in user's home directory (eg. /home/./user chroots into /home).

#mail_chroot =

Default MAIL environment to use when it's not set. By leaving this empty

dovecot tries to do some automatic detection as described in

doc/mail-storages.txt. There's a few special variables you can use, eg.:

%u - username

%n - user part in user@domain, same as %u if there's no domain

%d - domain part in user@domain, empty if user there's no domain

%h - home directory

See doc/variables.txt for full list. Some examples:

default_mail_env = maildir:/var/mail/%1u/%u/Maildir

default_mail_env = mbox:~/mail/:INBOX=/var/mail/%u

default_mail_env = mbox:/var/mail/%d/%n/:INDEX=/var/indexes/%d/%n

default_mail_env = mbox:~/mail/:INBOX=/var/mail/%u:INDEX=MEMORY

Space-separated list of fields to cache for all mails. Currently these

fields are allowed followed by a list of commands they speed up:

Envelope - FETCH ENVELOPE and SEARCH FROM, TO, CC, BCC, SUBJECT,

SENTBEFORE, SENTON, SENTSINCE, HEADER MESSAGE-ID,

HEADER IN-REPLY-TO

Body - FETCH BODY

Bodystructure - FETCH BODY, BODYSTRUCTURE

MessagePart - FETCH BODY[1.2.3] (ie. body parts), RFC822.SIZE,

SEARCH SMALLER, LARGER, also speeds up BODY/BODYSTRUCTURE

generation. This is always set with mbox mailboxes, and

also default with Maildir.

Different IMAP clients work in different ways, that's why Dovecot by default

only caches MessagePart which speeds up most operations. Whenever client

does something where caching could be used, the field is automatically marked

to be cached later. For example after FETCH BODY the BODY will be cached

for all new messages. Normally you should leave this alone, unless you know

what most of your IMAP clients are. Caching more fields than needed makes

the index files larger and generate useless I/O.

With maildir there's one extra optimization - if nothing is cached, indexing

the maildir becomes much faster since it's not opening any of the mail files.

This could be useful if your IMAP clients access only new mails.

#mail_cache_fields = MessagePart

Space-separated list of fields that Dovecot should never set to be cached.

Useful if you want to save disk space at the cost of more I/O when the fields

needed.

#mail_never_cache_fields =

Dovecot can notify client of new mail in selected mailbox soon after it's

received. This setting specifies the minimum interval in seconds between

new mail notifications to client - internally they may be checked more or

less often. Setting this to 0 disables the checking.

NOTE: Evolution client breaks with this option when it's trying to APPEND.

#mailbox_check_interval = 0

Like mailbox_check_interval, but used for IDLE command.

#mailbox_idle_check_interval = 30

Allow full filesystem access to clients. There's no access checks other than

what the operating system does for the active UID/GID. It works with both

maildir and mboxes, allowing you to prefix mailboxes names with eg. /path/

or ~user/.

#mail_full_filesystem_access = no

Maximum allowed length for mail keyword name. It's only forced when trying

to create new keywords.

#mail_max_keyword_length = 50

Save mails with CR+LF instead of plain LF. This makes sending those mails

take less CPU, especially with sendfile() syscall with Linux and FreeBSD.

But it also creates a bit more disk I/O which may just make it slower.

#mail_save_crlf = no

Use mmap() instead of read() to read mail files. read() seems to be a bit

faster with my Linux/x86 and it's better with NFS, so that's the default.

Note that OpenBSD 3.3 and older don't work right with mail_read_mmaped = yes.

#mail_read_mmaped = no

Don't use mmap() at all. This is required if you store indexes in remote

filesystems (NFS or clustered filesystem).

#mmap_disable = no

Don't write() to mmaped files. This is required for some operating systems

which use separate caches for them, such as OpenBSD.

#mmap_no_write = no

Don't use fcntl() locking. Alternatives are dotlocking and other tricks

which may be slower. Required for NFS.

fcntl_locks_disable = yes

By default LIST command returns all entries in maildir beginning with dot.

Enabling this option makes Dovecot return only entries which are directories.

This is done by stat()ing each entry, so it causes more disk I/O.

(For systems setting struct dirent->d_type, this check is free and it's

done always regardless of this setting)

#maildir_stat_dirs = no

Copy mail to another folders using hard links. This is much faster than

actually copying the file. This is problematic only if something modifies

the mail in one folder but doesn't want it modified in the others. I don't

know any MUA which would modify mail files directly. IMAP protocol also

requires that the mails don't change, so it would be problematic in any case.

If you care about performance, enable it.

#maildir_copy_with_hardlinks = no

Check if mails' content has been changed by external programs. This slows

down things as extra stat() needs to be called for each file. If changes are

noticed, the message is treated as a new message, since IMAP protocol

specifies that existing messages are immutable.

#maildir_check_content_changes = no

Which locking methods to use for locking mbox. There's four available:

dotlock: Create <mailbox>.lock file. This is the oldest and most NFS-safe

solution. If you want to use /var/mail/ like directory, the users

will need write access to that directory.

fcntl : Use this if possible. Works with NFS too if lockd is used.

flock : May not exist in all systems. Doesn't work with NFS.

lockf : May not exist in all systems. Doesn't work with NFS.

You can use multiple locking methods; if you do the order they're declared

in is important to avoid deadlocks if other MTAs/MUAs are using multiple

locking methods as well. Some operating systems don't allow using some of

them simultaneously.

#mbox_read_locks = fcntl #mbox_write_locks = dotlock fcntl

Maximum time in seconds to wait for lock (all of them) before aborting.

#mbox_lock_timeout = 300

If dotlock exists but the mailbox isn't modified in any way, override the

lock file after this many seconds.

#mbox_dotlock_change_timeout = 30

umask to use for mail files and directories

#umask = 0077

Drop all privileges before exec()ing the mail process. This is mostly

meant for debugging, otherwise you don't get core dumps. It could be a small

security risk if you use single UID for multiple users, as the users could

ptrace() each others processes then.

#mail_drop_priv_before_exec = no

Set max. process size in megabytes. Most of the memory goes to mmap()ing

files, so it shouldn't harm much even if this limit is set pretty high.

#mail_process_size = 256

Log prefix for mail processes. See doc/variables.txt for list of possible

variables you can use.

#mail_log_prefix = "%Up(%u): "

IMAP specific settings

protocol imap {

Login executable location.

#login_executable = /usr/libexec/dovecot/imap-login

IMAP executable location

#mail_executable = /usr/libexec/dovecot/imap

This would write rawlogs into ~/dovecot.rawlog/ directory:

#mail_executable = /usr/libexec/dovecot/rawlog /usr/libexec/dovecot/imap

Maximum IMAP command line length in bytes. Some clients generate very long

command lines with huge mailboxes, so you may need to raise this if you get

"Too long argument" or "IMAP command line too large" errors often.

#imap_max_line_length = 65536

Support for dynamically loadable modules.

#mail_use_modules = no #mail_modules = /usr/lib/dovecot/imap

Workarounds for various client bugs:

oe6-fetch-no-newmail:

Never send EXISTS/RECENT when replying to FETCH command. Outlook Express

seems to think they are FETCH replies and gives user "Message no longer

in server" error. Note that OE6 still breaks even with this workaround

if synchronization is set to "Headers Only".

outlook-idle:

Outlook and Outlook Express never abort IDLE command, so if no mail

arrives in half a hour, Dovecot closes the connection. This is still

fine, except Outlook doesn't connect back so you don't see if new mail

arrives.

#imap_client_workarounds = }

POP3 specific settings

protocol pop3 {

Login executable location.

#login_executable = /usr/libexec/dovecot/pop3-login

POP3 executable location

#mail_executable = /usr/libexec/dovecot/pop3

Don't try to set mails non-recent with POP3 sessions. This is mostly

intended to reduce disk I/O. With maildir it doesn't move files from

new/ to cur/, with mbox it doesn't write Status-header.

#pop3_mails_keep_recent = no

Support for dynamically loadable modules.

#mail_use_modules = no #mail_modules = /usr/lib/dovecot/pop3

Workarounds for various client bugs:

outlook-no-nuls:

Outlook and Outlook Express hang if mails contain NUL characters.

This setting replaces them with 0x80 character.

#pop3_client_workarounds = }

Authentication processes

You can have multiple authentication processes. With plaintext authentication

the password is checked against each process, the first one which succeeds is

used. This is useful if you want to allow both system users (/etc/passwd)

and virtual users to login without duplicating the system users into virtual

database.

Executable location

#auth_executable = /usr/libexec/dovecot/dovecot-auth

Set max. process size in megabytes.

#auth_process_size = 256

Space separated list of realms for SASL authentication mechanisms that need

them. You can leave it empty if you don't want to support multiple realms.

Many clients simply use the first one listed here, so keep the default realm

first.

#auth_realms =

Default realm/domain to use if none was specified. This is used for both

SASL realms and appending @domain to username in plaintext logins.

#auth_default_realm =

List of allowed characters in username. If the user-given username contains

a character not listed in here, the login automatically fails. This is just

an extra check to make sure user can't exploit any potential quote escaping

vulnerabilities with SQL/LDAP databases. If you want to allow all characters,

set this value to empty.

#auth_username_chars = abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@

Username to use for users logging in with ANONYMOUS SASL mechanism

#auth_anonymous_username = anonymous

More verbose logging. Useful for figuring out why authentication isn't

working.

#auth_verbose = no

auth default {

Space separated list of wanted authentication mechanisms:

plain digest-md5 cram-md5 apop anonymous

mechanisms = plain

Where user database is kept:

passwd: /etc/passwd or similiar, using getpwnam()

passwd-file <path>: passwd-like file with specified location

static uid=<uid> gid=<gid> home=<dir template>: static settings

vpopmail: vpopmail library

ldap <config path>: LDAP, see doc/dovecot-ldap.conf

pgsql <config path>: a PostgreSQL database, see doc/dovecot-pgsql.conf

mysql <config path>: a MySQL database, see doc/dovecot-mysql.conf

userdb = passwd

Where password database is kept:

passwd: /etc/passwd or similiar, using getpwnam()

shadow: /etc/shadow or similiar, using getspnam()

pam [<service> | *]: PAM authentication

checkpassword <path>: checkpassword executable authentication

passwd-file <path>: passwd-like file with specified location

vpopmail: vpopmail authentication

ldap <config path>: LDAP, see doc/dovecot-ldap.conf

pgsql <config path>: a PostgreSQL database, see doc/dovecot-pgsql.conf

mysql <config path>: a MySQL database, see doc/dovecot-mysql.conf

passdb = pam

User to use for the process. This user needs access to only user and

password databases, nothing else. Only shadow and pam authentication

requires roots, so use something else if possible. Note that passwd

authentication with BSDs internally accesses shadow files, which also

requires roots.

user = root

Directory where to chroot the process. Most authentication backends don't

work if this is set, and there's no point chrooting if auth_user is root.

#chroot =

Number of authentication processes to create

#count = 1

Require a valid SSL client certificate or the authentication fails.

#ssl_require_client_cert = no }

PAM doesn't provide a way to get uid, gid or home directory. If you don't

want to use a separate user database (passwd usually), you can use static

userdb.

#auth onlypam {

mechanisms = plain

userdb = static uid=500 gid=500 home=/var/mail/%u

passdb = pam

user = dovecot-auth

#}

#auth ldap {

mechanisms = plain

userdb = ldap /etc/dovecot-ldap.conf

passdb = ldap /etc/dovecot-ldap.conf

user = dovecot-auth

#}

#auth virtualfile {

mechanisms = plain digest-md5

userdb = passwd-file /etc/passwd.imap

passdb = passwd-file /etc/passwd.imap

user = dovecot-auth

#}

It's possible to export the authentication interface to other programs,

for example SMTP server which supports talking to Dovecot. Client socket

handles the actual authentication - you give it a username and password

and it returns OK or failure. So it's pretty safe to allow anyone access to

it. Master socket is used to a) query if given client was successfully

authenticated, b) userdb lookups.

listener sockets will be created by Dovecot's master process using the

settings given inside the auth section

#auth default_with_listener {

mechanisms = plain

passdb = passwd

userdb = pam

socket listen {

master {

path = /var/run/dovecot/auth-master

#mode = 0600

# Default user/group is the one who started dovecot-auth (root)

#user =

#group =

}

client {

path = /var/run/dovecot-auth-client

mode = 0660

}

}

#}

connect sockets are assumed to be already running, Dovecot's master

process only tries to connect to them. They don't need any other settings

than path for the master socket, as the configuration is done elsewhere.

Note that the client sockets must exist in login_dir.

#auth external {

socket connect {

master {

path = /var/run/dovecot/auth-master

}

}

#}