system call interposition using LD_PRELOAD

[Godmar Back <godmar at gmail dot com>]

Hi,

a student of mine is working on a project that requires system call
interposition. In the old days, this could be accomplished using a
LD_PRELOAD library that would redefine the system call entry points.

He tells me that for several years now, this is no longer possible with GNU
libc because functions such as fopen() do not dynamically link against the
stubs, but rather a local PLT is used. He also claims some system call
sequences are even inlined in parts of the libc code.

He is now considering changing libc, but finds that its design does not lend
itself easily to doing that.

If this is true, what is the new state of the practice with respect to
system call interposition?

I would like to hear other's experience/tips/recommendations. Thank you.

?- Godmar