Bug 214715

Summary:	improve thread safety of libcap
Product:	Tools	Reporter:	Andrew G. Morgan (morgan)
Component:	libcap	Assignee:	Andrew G. Morgan (morgan)
Status:	RESOLVED CODE_FIX
Severity:	normal
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	n/a	Subsystem:
Regression:	No	Bisected commit-id:

Description Andrew G. Morgan 2021-10-14 03:53:19 UTC

Consider the case of two threads operating simultaneously on a single cap_t value. There are cases where libcap APIs can observe partially updated state in such a cap_t value because one is reading properties of that set while the other is writing them.

The Go API carefully locks Set values while operating on them, we should restore parity by having libcap do something similar. I'm going to use the __atomic_* primitives to avoid mandatory libthread/libpsx dependencies.

Comment 1 Andrew G. Morgan 2021-10-23 04:18:06 UTC

The following commits implemented this:

https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=aca076443591ba18438b60e41294b59a324daf04

https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=5b16d336d009bc927a0545b9ecbb91942f1742f5

https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=73194f5369286e10c9e19cbd71de59c3b45b5789

https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=140fa8438bde4e6affe8aefa6fbf077eae968686

https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=3d60128581126f69e31ee963d47cef456ee9e371

These will all be part of the libcap-2.60 release.