[RFC,v4,07/12] __wr_after_init: Documentation: self-protection

Commit Message

Igor Stoppa Feb. 11, 2019, 11:27 p.m. UTC

Update the self-protection documentation, to mention also the use of the
__wr_after_init attribute.

Signed-off-by: Igor Stoppa <[e-mail]>

CC: Andy Lutomirski <[e-mail]>
CC: Nadav Amit <[e-mail]>
CC: Matthew Wilcox <[e-mail]>
CC: Peter Zijlstra <[e-mail]>
CC: Kees Cook <[e-mail]>
CC: Dave Hansen <[e-mail]>
CC: Mimi Zohar <[e-mail]>
CC: Thiago Jung Bauermann <[e-mail]>
CC: Ahmed Soliman <[e-mail]>
CC: [e-mail]
CC: [e-mail]
CC: [e-mail]
CC: [e-mail]
---
 Documentation/security/self-protection.rst | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

Patch

diff --git a/Documentation/security/self-protection.rst b/Documentation/security/self-protection.rst
index f584fb74b4ff..df2614bc25b9 100644
--- a/Documentation/security/self-protection.rst
+++ b/Documentation/security/self-protection.rst
@@ -84,12 +84,14 @@  For variables that are initialized once at ``__init`` time, these can
 be marked with the (new and under development) ``__ro_after_init``
 attribute.
 
-What remains are variables that are updated rarely (e.g. GDT). These
-will need another infrastructure (similar to the temporary exceptions
-made to kernel code mentioned above) that allow them to spend the rest
-of their lifetime read-only. (For example, when being updated, only the
-CPU thread performing the update would be given uninterruptible write
-access to the memory.)
+Others, which are statically allocated, but still need to be updated
+rarely, can be marked with the ``__wr_after_init`` attribute.
+
+The update mechanism must avoid exposing the data to rogue alterations
+during the update. For example, only the CPU thread performing the update
+would be given uninterruptible write access to the memory.
+
+Currently there is no protection available for data allocated dynamically.
 
 Segregation of kernel memory from userspace memory
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~