passt/linux_dep.h, branch 2025_05_03.587980c Plug A Simple Socket Transport linux_dep: Fix CLOSE_RANGE_UNSHARE availability handling 2024-11-08T07:26:17+00:00 David Gibson david@gibson.dropbear.id.au 2024-11-08T02:53:29+00:00 14dd70e2b33941f1f7663969574278873c9e3d35 If CLOSE_RANGE_UNSHARE isn't defined, we define a fallback version of close_range() which is a (successful) no-op. This is broken in several ways: * It doesn't actually fix compile if using old kernel headers, because the caller of close_range() still directly uses CLOSE_RANGE_UNSHARE unprotected by ifdefs * Even if it did fix the compile, it means inconsistent behaviour between a compile time failure to find the value (we silently don't close files) and a runtime failure (we die with an error from close_range()) * Silently not closing the files we intend to close for security reasons is probably not a good idea in any case We don't want to simply error if close_range() or CLOSE_RANGE_UNSHARE isn't available, because that would require running on kernel >= 5.9. On the other hand there's not really any other way to flush all possible fds leaked by the parent (close() in a loop takes over a minute). So in this case print a warning and carry on. As bonus this fixes a cppcheck error I see with some different options I'm looking to apply in future. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> 
If CLOSE_RANGE_UNSHARE isn't defined, we define a fallback version of
close_range() which is a (successful) no-op.  This is broken in several
ways:
 * It doesn't actually fix compile if using old kernel headers, because
   the caller of close_range() still directly uses CLOSE_RANGE_UNSHARE
   unprotected by ifdefs
 * Even if it did fix the compile, it means inconsistent behaviour between
   a compile time failure to find the value (we silently don't close files)
   and a runtime failure (we die with an error from close_range())
 * Silently not closing the files we intend to close for security reasons
   is probably not a good idea in any case

We don't want to simply error if close_range() or CLOSE_RANGE_UNSHARE isn't
available, because that would require running on kernel >= 5.9.  On the
other hand there's not really any other way to flush all possible fds
leaked by the parent (close() in a loop takes over a minute).  So in this
case print a warning and carry on.

As bonus this fixes a cppcheck error I see with some different options I'm
looking to apply in future.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
linux_dep: Move close_range() conditional handling to linux_dep.h 2024-11-08T07:26:15+00:00 David Gibson david@gibson.dropbear.id.au 2024-11-08T02:53:28+00:00 d64f25724399fbb4ba9d36eda7e17984a4c6c91c util.h has some #ifdefs and weak definitions to handle compatibility with various kernel versions. Move this to linux_dep.h which handles several other similar cases. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> 
util.h has some #ifdefs and weak definitions to handle compatibility with
various kernel versions.  Move this to linux_dep.h which handles several
other similar cases.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
log: Only check for FALLOC_FL_COLLAPSE_RANGE availability at runtime 2024-11-08T07:25:58+00:00 David Gibson david@gibson.dropbear.id.au 2024-11-08T02:53:27+00:00 b84cd05098275a7625223141d019f8af5a17323b log.c has several #ifdefs on FALLOC_FL_COLLAPSE_RANGE that won't attempt to use it if not defined. But even if the value is defined at compile time, it might not be available in the runtime kernel, so we need to check for errors from a fallocate() call and fall back to other methods. Simplify this to only need the runtime check by using linux_dep.h to define FALLOC_FL_COLLAPSE_RANGE if it's not in the kernel headers. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> 
log.c has several #ifdefs on FALLOC_FL_COLLAPSE_RANGE that won't attempt
to use it if not defined.  But even if the value is defined at compile
time, it might not be available in the runtime kernel, so we need to check
for errors from a fallocate() call and fall back to other methods.

Simplify this to only need the runtime check by using linux_dep.h to define
FALLOC_FL_COLLAPSE_RANGE if it's not in the kernel headers.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
linux_dep: Generalise tcp_info.h to handling Linux extension compatibility 2024-11-07T11:47:16+00:00 David Gibson david@gibson.dropbear.id.au 2024-11-06T06:54:14+00:00 0d7b8201ed5788416d1b36fc3a554b61ad10c201 tcp_info.h exists just to contain a modern enough version of struct tcp_info for our needs, removing compile time dependency on the version of kernel headers. There are several other cases where we can remove similar compile time dependencies on kernel version. Prepare for that by renaming tcp_info.h to linux_dep.h. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com> 
tcp_info.h exists just to contain a modern enough version of struct
tcp_info for our needs, removing compile time dependency on the version of
kernel headers.  There are several other cases where we can remove similar
compile time dependencies on kernel version.  Prepare for that by renaming
tcp_info.h to linux_dep.h.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>