Arch Linux

lamarpavel

Member

Registered: 2015-10-18

Posts: 48

[solved] Causes for permission missmatch on installed files

I did a pacman -Qkk today and found a few files reporting a :warning: [...] (Permissions mismatch). For some of them, this seemed okay-ish, like /boot/grub/grub.cfg, which has 0600 and is owned root:root. It's not impossible that I changed that myself, though I can't remember doing so. Reading pacmans manpage, I could not find out how to display the supposed permissions, though. Is there a utility for displaying the difference in supposed and actual permission?

Moving on, there was one file that actually worried me and that was /usr/lib/libkeyutils.so.1.6, which had a permission of 777 (root:root). No chance that I did that knowingly. After re-installing keyutils, the permissions are 755 (root:root).
What could be the cause of this? Should I be worried? I figure there is not much of a chance to find out who or what modified that file?

Last edited by lamarpavel (2018-05-18 19:25:03)

mpan

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Registered: 2012-08-01

Posts: 1,597

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Re: [solved] Causes for permission missmatch on installed files

Many files are generated and therefore may be overwriten: possibly with different permissions. /boot/grub/grub.cfg is one of them, generated usually by grub-mkconfig during one of the standard installation steps.

To check expected permissions:

$ tar -tJvf "/var/cache/pacman/pkg/$PKG_FILE"  | grep -F "$FILENAME"

The $FILENAME should not contain the leading slash. For example:

 $ tar -tJvf /var/cache/pacman/pkg/grub-2\:2.02-5-x86_64.pkg.tar.xz  | grep -F boot/grub/grub.cfg
-rw-r--r-- root/root      4087 2018-03-14 21:56 boot/grub/grub.cfg

The case of /usr/lib/libkeyutils.so.1.6 is strange indeed. It should be 755. I have no idea, why it is 777 on your system — except the usual suspects: dirty hacks to make something work few years earlier and forgeting about it, AUR packages etc.

Last edited by mpan (2018-05-18 08:16:19)

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Paperclips in avatars? | Sometimes I seem a bit harsh — don’t get offended too easily!

lamarpavel

Member

Registered: 2015-10-18

Posts: 48

Re: [solved] Causes for permission missmatch on installed files

Thank you, that answer was very helpful. Based on your hint I'm now going through all my archived packages to see if any of them modify libkeyutils.so.1.6:

for F in *.tar.xz; do ret="$(tar -tJvf "$F" 2>/dev/null | grep -F libkeyutils.so.1.6)" ; if [ -n "$ret" ]; then echo "$F\n$ret"; fi; done

That's going to take a while, but maybe something will turn up in some old version of a package or in an aur package.

lamarpavel

Member

Registered: 2015-10-18

Posts: 48

Re: [solved] Causes for permission missmatch on installed files

Well, no luck finding a culprit in either the official or the aur packages that I have archived.
At least it seems the file wasn't altered (permanently) since then pacman -Qkk would have reported a checksum missmatch as well as a permission missmatch. (right?) Still, I feel uneasy about this.

Anyway, I'll mark this thread solved. Thanks for your help, mpan.

mpan

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Registered: 2012-08-01

Posts: 1,597

Website

Re: [solved] Causes for permission missmatch on installed files

For the future: the code from your post can be replaced with:

pacman -Fs libkeyutils.so.1.6

Note: you need to synchronize files database earlier, using sudo pacman -Fy — this is being done separately from the sync database! Alternatively you may use:

pkgfile libkeyutils.so.1.6

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Paperclips in avatars? | Sometimes I seem a bit harsh — don’t get offended too easily!

lamarpavel

Member

Registered: 2015-10-18

Posts: 48

Re: [solved] Causes for permission missmatch on installed files

Good to know. But that would only search through the database in its current form, doesn't it? If I want to search through old packages that might have changed my files some time in the past, or packages built from the AUR, I would still need to search through the pkg.tar.xz archives.

mpan

Member

Registered: 2012-08-01

Posts: 1,597

Website

Re: [solved] Causes for permission missmatch on installed files

Yes, you are right on that.

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Paperclips in avatars? | Sometimes I seem a bit harsh — don’t get offended too easily!