Created files shouldn't have the execute bit set

[fabio]

Many files created by 0ad (e.g. cache, screenshots, ...) have the x (execute) bit set on linux. They should be created using the default mask.

[Jan Wassenberg]

Thanks for mentioning this. The culprit is S_IRWXO|S_IRWXU|S_IRWXG at file.cpp:59. What should we write instead?

[fabio]

Hi, you can change it to:

S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH

This is the same of what's in currently without the executable flag (S_IRWXU=S_IRUSR|S_IWUSR|S_IXUSR, ...), also ordered better (user, group, others - *USR, *GRP, *OTH).

See also ​http://opengroup.org/onlinepubs/007908775/xsh/sysstat.h.html

Tested, it works as expected.

[Jan Wassenberg]

(In [8554]) avoid setting executable bit in files/dirs we create thanks to fabio for reporting + a suggested fix. fixes #648

[fabio]

Now test fails:

Running 251 tests....................................................................................................................lib_errors.cpp(110): Function call failed: return value was -110300 (Insufficient access rights to open file)
Function call failed: return value was -110300 (Insufficient access rights to open file)
Location: lib_errors.cpp:110 (LibError_from_errno)

I suspect the execute bit shouldn't be removed from the directories, it has a different meaning here that forbids changing directory.

[Philip Taylor]

Yeah, directories will need X. Also we probably shouldn't give W (and maybe not give R) to group or other, since it's not good for security if some random user on the system can overwrite those files.

[fabio]

Note however that the W from g/o gets stripped away by system umask which tipically is 0022, so it could eventually be left since screenshot/cache file doesn't keep any secret.

[fabio]

I was meaning that R could be left but indeed W should be also removed.

[Jan Wassenberg]

(Yikes, this wiki isn't terribly great for real-time updates ;) )

OK. (Windows isn't doing these security checks, sorry that you have to debug the permissions.) The previous directory mode was S_IRWXU. Should we add X for O and G, or leave it at that?

since it's not good for security if some random user on the system can overwrite those files.

Yeah. I was previously assuming there might be directories shared between users (cache). However, the XDG paths default to something under the home directory. Are we sure there will never need to be sharing between users? (And are different users on the same machine placed in the same group, or is that level of access control seldom used?)

Attempt at summary thus far: files = 0644, dirs = 0755?

[Philip Taylor]

Users should only use the system-wide read-only installed cache (if we pre-cache .xmb/etc files in release packages, which we don't yet but should), and their own per-user writeable cache. Any other kind of shared cache would be insecure (one user could silently introduce data files that exploit vulnerabilities when another user runs the game), and unnecessary (the caches aren't big or slow), so I think we'll never want to do that.

​XDG basedir says directories should be created with 0700, so we should stick with that. It doesn't say anything about files - 0644 sounds sensible to me.

[Jan Wassenberg]

(In [8558]) fix file/dir mode bits fixes #648 also fix self-test on ICC 12