-sysperms=false (default) doesn't appear to do anything #13371

Despite -sysperms=false (default) docs saying files will be created with perms 077, none of my default-created datadirs appear to have any permissions aside from 0600. Maybe I'm misreading the docs but it appears umask(077) isnt doing anything.

can work on this.

@TheBlueMatt

Despite -sysperms=false (default) docs saying files will be created with perms 077, none of my default-created datadirs appear to have any permissions aside from 0600. Maybe I'm misreading the docs but it appears umask(077) isnt doing anything.

-sysperms=false makes Bitcoin Core create files with umask = 077 rather permissions 077. And this implies 0600 permissions for regular files and 0700 for directories. See: Debian Reference

So, Bitcoin Core creates files as expected ;)

Despite -sysperms=false (default) docs saying files will be created with perms 077

I assume you're referring to these docs:

$ bitcoind --help | grep --after-context 3 sysperms
  -sysperms
       Create new files with system default permissions, instead of umask 077
       (only effective with disabled wallet functionality)

I don't know where to find bitcoind's default values, but you mention this setting is by default false, which makes sense given what it does.

Running umask on my Debian-based distro returns my system default umask 002, meaning the system (that is, not my user) will create new files with permissions u=rwx g=rwx o=rx.

Perhaps the help text would be more readable if it said:

Create new files with system default umask, instead of umask 077.

In fact, this is what the commit message that introduced this change said!

• bdd5b58 Add option -sysperms to disable 077 umask (create new files with system default umask)

Link to help text: https://github.com/bitcoin/bitcoin/blob/master/src/init.cpp#L430

Shall I make that change @TheBlueMatt ?

Hello, I'd like to tackle this issue. Is this issue still open ?

@TheBlueMatt

Despite -sysperms=false (default) docs saying files will be created with perms 077, none of my default-created datadirs appear to have any permissions aside from 0600. Maybe I'm misreading the docs but it appears umask(077) isnt doing anything.

-sysperms=false makes Bitcoin Core create files with umask = 077 rather permissions 077. And this implies 0600 permissions for regular files and 0700 for directories. See: Debian Reference

So, Bitcoin Core creates files as expected ;)

Just to check:

System: Ubuntu 22.04 umask: 002 (OS default)

I've tested creating a new datadir on master with default bitcoind settings (i.e. without setting -sysperms and with wallet enabled): bitcoind -signet. We expect bitcoin to use umask 077 by default.

For directories expect: 777 - 077 = 700 = rwx------ For files expect:      666 - 077 = 600 = rw-------

It created the following:

will@ubuntu in /tmp
❯ exa -alR .bitcoin
drwxrwxr-x - will 15 Nov 14:22 signet
drwxrwxr-x - will 15 Nov 14:22 wallets

.bitcoin/signet:
.rw-------    0 will 15 Nov 14:22 .lock
.rw-------   37 will 15 Nov 14:22 anchors.dat
.rw-------   31 will 15 Nov 14:22 banlist.json
drwx------    - will 15 Nov 14:22 blocks
drwx------    - will 15 Nov 14:22 chainstate
.rw------- 7.0k will 15 Nov 14:22 debug.log
.rw------- 248k will 15 Nov 14:22 fee_estimates.dat
.rw-------   18 will 15 Nov 14:22 mempool.dat
.rw-------   99 will 15 Nov 14:22 onion_v3_private_key
.rw-------  11k will 15 Nov 14:22 peers.dat
.rw-rw-r--    4 will 15 Nov 14:22 settings.json
drwxrwxr-x    - will 15 Nov 14:22 wallets

It seems to have used the system umask to create .bitcoin/, signet/, signet/wallets/ and top level wallets/ directories (777-002=775), but not blocks/ and chainstate/ directories. It has also used system umask to create the settings.json file.

This happens because ReadConfigFiles() is called before AppInitBasicSetup() (which sets the umask) and ReadConfigFiles will internally call GetConfigFile() which in turn calls AbsPathForConfigVal(), where calling either of GetDataDirNet() or GetDataDirBase() will init the base file structure before the -sysperms flag has been parsed.

Starting with bitcoind -signet -sysperms -disablewallet:

For directories expect: 777 - 002 = 775 = rwxrwxr-x For files expect:      666 - 002 = 664 = rw-rw-r--

Which creates the following:

will@ubuntu in /tmp
❯ exa -al -R .bitcoin_sysperms/
drwxrwxr-x - will 15 Nov 16:18 signet
drwxrwxr-x - will 15 Nov 16:17 wallets

.bitcoin_sysperms/signet:
.rw-rw-r--    0 will 15 Nov 16:18 .lock
.rw-rw-r--   37 will 15 Nov 16:18 anchors.dat
.rw-rw-r--   31 will 15 Nov 16:18 banlist.json
drwxrwxr-x    - will 15 Nov 16:18 blocks
drwxrwxr-x    - will 15 Nov 16:18 chainstate
.rw-rw-r-- 6.5k will 15 Nov 16:18 debug.log
.rw-rw-r-- 248k will 15 Nov 16:18 fee_estimates.dat
.rw-rw-r--   18 will 15 Nov 16:18 mempool.dat
.rw-rw-r--   99 will 15 Nov 16:18 onion_v3_private_key
.rw-rw-r--  12k will 15 Nov 16:18 peers.dat
.rw-rw-r--    4 will 15 Nov 16:18 settings.json
drwxrwxr-x    - will 15 Nov 16:17 wallets

I have a PR which results in the following (correct) filestructure when started without the -sysperms flag:

will@ubuntu in /tmp/13371
❯ exa -al -R
drwx------ - will 16 Nov 13:47 .bitcoin

./.bitcoin:
drwx------ - will 16 Nov 13:47 signet
drwx------ - will 16 Nov 13:47 wallets

./.bitcoin/signet:
.rw-------    0 will 16 Nov 13:47 .lock
.rw-------   37 will 16 Nov 13:47 anchors.dat
.rw-------   31 will 16 Nov 13:47 banlist.json
drwx------    - will 16 Nov 13:47 blocks
drwx------    - will 16 Nov 13:47 chainstate
.rw------- 7.1k will 16 Nov 13:47 debug.log
.rw------- 248k will 16 Nov 13:47 fee_estimates.dat
.rw-------   18 will 16 Nov 13:47 mempool.dat
.rw-------   99 will 16 Nov 13:47 onion_v3_private_key
.rw-------  16k will 16 Nov 13:47 peers.dat
.rw-------    4 will 16 Nov 13:47 settings.json
drwx------    - will 16 Nov 13:47 wallets

And with -sysperms -disablewallet:

will@ubuntu in /tmp/13371
❯ exa -al -R
drwxrwxr-x - will 16 Nov 13:54 .bitcoin_sysperms

./.bitcoin_sysperms:
drwxrwxr-x - will 16 Nov 13:55 signet
drwxrwxr-x - will 16 Nov 13:54 wallets

./.bitcoin_sysperms/signet:
.rw-rw-r--    0 will 16 Nov 13:55 .lock
.rw-rw-r--   37 will 16 Nov 13:55 anchors.dat
.rw-rw-r--   31 will 16 Nov 13:55 banlist.json
drwxrwxr-x    - will 16 Nov 13:55 blocks
drwxrwxr-x    - will 16 Nov 13:55 chainstate
.rw-rw-r-- 7.0k will 16 Nov 13:55 debug.log
.rw-rw-r-- 248k will 16 Nov 13:55 fee_estimates.dat
.rw-rw-r--   18 will 16 Nov 13:55 mempool.dat
.rw-rw-r--   99 will 16 Nov 13:55 onion_v3_private_key
.rw-rw-r--  14k will 16 Nov 13:55 peers.dat
.rw-rw-r--    4 will 16 Nov 13:55 settings.json
drwxrwxr-x    - will 16 Nov 13:54 wallets

I would be interested in more feedback on whether such a change is desirable because changing the default file permissions could possibly break things upstream for other projects?