proftpd
Repeated reload operations may cause memory leakage.
What I Did
Run the kill -hup {pid} command for the proftpd process repeatedly. As a result, the RSS of the process increases. Memory leakage may occur.
After analysis, I think that during the reload process, a new tls_ticket_key is generated each time, and mlock is performed, which causes the RSS of the process to increase continuously. It is necessary to save the tls_ticket_key, but does it need to be regenerated for each reload?
What I Expected/Wanted
The reload process is running, but the memory usage of the process does not increase.
ProFTPD Version and Configuration
Compile-time Settings:
Version: 1.3.8b (maint)
Platform: LINUX [Linux 5.10.0- aarch64]
Built: Wed Apr 10 2024 09:05:58 UTC
Built With:
configure '--build=aarch64-linux-gnu' '--host=aarch64-linux-gnu' '--program-prefix=' '--disable-dependency-tracking' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib64' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/var/lib' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--libexecdir=/usr/libexec/proftpd' '--localstatedir=/run/proftpd' '--disable-strip' '--enable-ctrls' '--enable-dso' '--enable-facl' '--enable-ipv6' '--enable-nls' '--enable-openssl' '--disable-pcre' '--disable-redis' '--enable-shadow' '--enable-tests=nonetwork' '--with-libraries=/usr/lib64/mariadb' '--with-includes=/usr/include/mysql' '--with-modules=mod_readme:mod_auth_pam:mod_tls' '--with-shared=mod_sql:mod_sql_passwd:mod_sql_mysql:mod_sql_sqlite:mod_quotatab:mod_quotatab_file:mod_quotatab_ldap:mod_quotatab_radius:mod_quotatab_sql:mod_ldap:mod_ban:mod_ctrls_admin:mod_facl:mod_load:mod_vroot:mod_radius:mod_ratio:mod_rewrite:mod_site_misc:mod_exec:mod_shaper:mod_wrap2:mod_wrap2_file:mod_wrap2_sql:mod_copy:mod_deflate:mod_ifversion:mod_qos:mod_sftp:mod_sftp_pam:mod_sftp_sql:mod_tls_shmcache:mod_unique_id:mod_ifsession' 'build_alias=aarch64-linux-gnu' 'host_alias=aarch64-linux-gnu' 'CFLAGS=-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/generic-hardened-cc1 -fasynchronous-unwind-tables -fstack-clash-protection' 'LDFLAGS=-Wl,-z,relro -Wl,-z,now -specs=/usr/lib/rpm/generic-hardened-ld' 'CXXFLAGS=-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/generic-hardened-cc1 -fasynchronous-unwind-tables -fstack-clash-protection -fexceptions'
CFLAGS: -g2 -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fstack-protector-strong -grecord-gcc-switches -specs=/usr/lib/rpm/generic-hardened-cc1 -fasynchronous-unwind-tables -fstack-clash-protection -Wall -fno-omit-frame-pointer -fno-strict-aliasing -Werror=implicit-function-declaration
LDFLAGS: -L$(top_srcdir)/lib -L$(top_builddir)/lib -Wl,-z,relro -Wl,-z,now -specs=/usr/lib/rpm/generic-hardened-ld -rdynamic -L/usr/lib64/mariadb -L/usr/lib64/
LIBS: -lacl -lssl -lcrypto -lcap -lssl -lcrypto -lpam -lsupp -lattr -lresolv -lresolv -lcrypt -pthread
Files:
Configuration File:
/etc/proftpd.conf
Pid File:
/run/proftpd/proftpd.pid
Scoreboard File:
/run/proftpd/proftpd.scoreboard
Header Directory:
/usr/include/proftpd
Shared Module Directory:
/usr/libexec/proftpd
Info:
+ Max supported UID: 4294967295
+ Max supported GID: 4294967295
Features:
- Autoshadow support
+ Controls support
+ curses support
- Developer support
+ DSO support
+ IPv6 support
+ Largefile support
- Lastlog support
- Memcache support
+ ncursesw support
+ NLS support
+ OpenSSL support (OpenSSL 1.1.1m 14 Dec 2021, FIPS enabled)
- PCRE support
+ POSIX ACL support
- Redis support
+ Sendfile support
+ Shadow file support
- Sodium support
+ Trace support
+ xattr support
Tunable Options:
PR_TUNABLE_BUFFER_SIZE = 1024
PR_TUNABLE_DEFAULT_RCVBUFSZ = 8192
PR_TUNABLE_DEFAULT_SNDBUFSZ = 8192
PR_TUNABLE_ENV_MAX = 2048
PR_TUNABLE_GLOBBING_MAX_MATCHES = 100000
PR_TUNABLE_GLOBBING_MAX_RECURSION = 8
PR_TUNABLE_HASH_TABLE_SIZE = 40
PR_TUNABLE_LOGIN_MAX = 256
PR_TUNABLE_NEW_POOL_SIZE = 512
PR_TUNABLE_PATH_MAX = 4096
PR_TUNABLE_SCOREBOARD_BUFFER_SIZE = 80
PR_TUNABLE_SCOREBOARD_SCRUB_TIMER = 30
PR_TUNABLE_SELECT_TIMEOUT = 30
PR_TUNABLE_TIMEOUTIDENT = 10
PR_TUNABLE_TIMEOUTIDLE = 600
PR_TUNABLE_TIMEOUTLINGER = 10
PR_TUNABLE_TIMEOUTLOGIN = 300
PR_TUNABLE_TIMEOUTNOXFER = 300
PR_TUNABLE_TIMEOUTSTALLED = 3600
PR_TUNABLE_XFER_SCOREBOARD_UPDATES = 10
It is necessary to save the tls_ticket_key, but does it need to be regenerated for each reload?
Generating a new key for encrypting TLS tickets, on each reload, helps ensure that these keys are unique across ProFTPD installations and hosts, and are not constant over long periods of time.
I'll look into checking whether mlock(2) is needed during a restart (for it is needed on process startup).
Note that the mod_tls module used to properly scrub the in-memory mlock(2)'d keys from memory, prior to https://github.com/proftpd/proftpd/pull/353. See Bug#4260 for the reasons why that behavior was changed.
If you think this is a mechanism issue, I'll close this issue.
For now, I'll close this. If/when more specific details about memory usage increases caused by repeated SIGHUP becomes available, we can open a new ticket to investigate then. Thanks!