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| author | Frank Ch. Eigler <fche@elastic.org> | 2009-09-16 22:32:28 -0400 |
|---|---|---|
| committer | Frank Ch. Eigler <fche@elastic.org> | 2009-09-16 22:37:24 -0400 |
| commit | 6ecd877049008c5abe9c6720ea8fc64732f47eb5 (patch) | |
| tree | 407a536c1271b8e5757899e461c481e599266d67 /tapset/DEVGUIDE | |
| parent | 6846cfc8a5cdb24fccb19037b27a180d2300ee09 (diff) | |
| download | systemtap-steved-6ecd877049008c5abe9c6720ea8fc64732f47eb5.tar.gz systemtap-steved-6ecd877049008c5abe9c6720ea8fc64732f47eb5.tar.xz systemtap-steved-6ecd877049008c5abe9c6720ea8fc64732f47eb5.zip | |
PR10650: markup some unprivileged-safe tapset functions
Add /* unprivileged */ to a variety of tapset embedded-c functions,
together with uid-assertion-checking code as needed. This is only
an initial set, and may need to grow or shrink after further testing.
Prototyped-By: Dave Brolley <brolley@redhat.com>
* runtime/runtime.h (is_myproc, assert_is_myproc): New macros.
* runtime/addr-map.c (lookup_bad_addr): Reject if !is_myproc
in unprivileged mode.
* runtime/print.c (_stp_print_kernel_info): Add unprivileged
mode info.
* tapset/DEVGUIDE: Document /* pure */ and /* unprivileged */.
* tapset/*.stp: Add /* unprivileged */ here and there, in
questionable cases along with an assert_is_myproc().
Diffstat (limited to 'tapset/DEVGUIDE')
| -rw-r--r-- | tapset/DEVGUIDE | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/tapset/DEVGUIDE b/tapset/DEVGUIDE index 693521a8..5d7c8658 100644 --- a/tapset/DEVGUIDE +++ b/tapset/DEVGUIDE @@ -244,6 +244,23 @@ potentially be invalid. If you're not sure, err on the side of caution. The cost of using kread() is small compared to the cost of your tapset inadvertently crashing a system! +Add the string + /* pure */ +into the body of the embedded-C function if it has no side-effects +such as changing external state, so that systemtap could elide +(optimize away) a call to the function if its results are unused. + +Add the string + /* unprivileged */ +into the body of the embedded-C function, only if it is safe for use +by unprivileged users. In general, this requires the function to be +absolutely robust with respect to its inputs, and expose/modify no +information except that belonging to the user's own processes. +(The assert_is_myproc() macro may help enforce this.) Roughly +speaking, it should only perform operations that the same user +could already do from ordinary userspace interfaces. + + Review & Submission ------------------- All new tapsets and major changes should be reviewed "early and often" |