Zack's Kernel News
Zack's Kernel News
Chronicler Zack Brown reports on the latest news, views, dilemmas, and developments within the Linux kernel community.
Speeding Up Security Access Checks
Linus Torvalds sent a patch to Al Viro, trying to eke out a bit more speed from the VFS. In particular, he felt that some of the security checks from SELinux could be speeded up by moving the relevant data out of SELinux itself and directly into the inode data structure. This way, when looking up file paths, the code could avoid doing an extra pointer dereference.
Casey Schaufler responded to this as the maintainer of Smack, a kernel module that implements access controls for data and running processes. He said that some of the security stuff he'd been working on would reintroduce exactly the kind of pointer dereference that Linus had been trying to eliminate.
He also said that this idea of migrating data into the inode was something he hadn't known was an option. He said, "I have been working on the assumption that the single blob pointer was all that could ever go into the inode. If that's not true stacking could get considerably easier and could have less performance impact."
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