Quite a few places read an integer sysctl and parse it manually, each in
its own way: some via read_one_line_file() on a hand-built /proc/sys/
path, some via sysctl_read() followed by safe_atoX(), parse_boolean() or
even a plain string comparison, and parsing into various integer types
(int, unsigned, unsigned long, uint64_t).
Add three helpers, sysctl_read_int(), sysctl_read_unsigned() and
sysctl_read_uint64(), plus a sysctl_read_uint32() alias for
sysctl_read_unsigned() for places where the value is stored in a
strictly 32-bit type (such as uid_t/gid_t), and a sysctl_read_lu()
wrapper that maps to sysctl_read_uint32() or sysctl_read_uint64(),
depending on the size of unsigned long. Then port all these users over:
- kernel.cap_last_cap (cap_last_cap() and test-capability-util)
- kernel.random.poolsize (random_pool_size())
- fs.nr_open (read_nr_open())
- kernel.pid_max and kernel.threads-max (procfs_get_pid_max(),
procfs_get_threads_max())
- net.unix.max_dgram_qlen (PID 1's bump_unix_max_dgram_qlen())
- kernel.overflowuid and kernel.overflowgid (PID 1's taint logic)
- fs.protected_hardlinks (tmpfiles)
- kernel.apparmor_restrict_unprivileged_userns (test-execute)
Note that fs.protected_hardlinks is read as integer instead of boolean
now, since the kernel exposes it as such (even if it only accepts 0 and
1 for now). This matters even more for its siblings fs.protected_regular
and fs.protected_fifos which accept 0, 1 and 2, and hence cannot be
parsed via parse_boolean().
PID 1 keeps tainting itself if kernel.overflowuid/kernel.overflowgid
cannot be parsed, as before, but not if they cannot be read at all.
(cherry picked from commit 9ccd43072e)
(cherry picked from commit 334c06a1ba)
Let's not leak details from src/shared and src/libsystemd into
src/basic, even though you can't actually do anything useful with
just forward declarations from src/shared.
The sd-forward.h header is put in src/libsystemd/sd-common as we
don't have a directory for shared internal headers for libsystemd
yet.
Let's also rename forward.h to basic-forward.h to keep things
self-explanatory.
The RA's Retransmission Timer field was being ignored. This resolves the IPv6
Core Conformance test, v6LC.2.1.5 [1].
Retransmission Timer is a 32-bit unsigned integer. The time, in milliseconds,
between retransmitted Neighbor Solicitation messages. Used by the Address
Resolution and Neighbor Unreachability Detection (NUD) algorithm.
Support setting a default value for the neighbour retransmission timer value with:
[Network]
IPv6RetransmissionTimeSec=<int>
By default, upon receiving a Router Advertisement with the Retransmission Timer
field set to a non-zero value, it will update the kernel's retransmit timer value.
To disable this behaviour, configure the UseIPv6RetransmissionTime= under the
[IPv6AcceptRA] section.
[IPv6AcceptRA]
UseIPv6RetransmissionTime=<bool>
RFC4861: Neighbor Discovery in IPv6
* Section 4.2 RA Message Format.
* Section 6.3.4 Processing Received Router Advertisements
A Router Advertisement field (e.g., Cur Hop Limit, Reachable Time,
and Retrans Timer) may contain a value denoting that it is
unspecified. In such cases, the parameter should be ignored and the
host should continue using whatever value it is already using. In
particular, a host MUST NOT interpret the unspecified value as
meaning change back to the default value that was in use before the
first Router Advertisement was received.
The RetransTimer variable SHOULD be copied from the Retrans Timer
field, if the received value is non-zero.
References
[1] IPv6 Core Conformance Spec (PDF)
Lennart Poettering