basic/fileio: fix reading of not-too-small virtual files
This code is trying to do two things: when reading a file with working
st.st_size, detect when the file size changes between the fstat() and our
allocation of the buffer based on the returned size, and the subsequent read().
When reading a file without st.st_size, read up to READ_FULL_BYTES_MAX.
But this second scenario was partially broken: we'd start with size = 4095, and
double the size up to three times, i.e. up to 32767. But we want to read up to
READ_FULL_BYTES_MAX.
So let's listentangle the two cases a bit: if a file returns non-zero st._size,
proceed as before. But if we don't know the size, let's immediately allocate
the buffer of maximum size of READ_FULL_BYTES_MAX. I think that allocating 4MB
and 1MB is going to take pretty much the same time as long as the memory is not
written to, so by allocating 1MB, 2MB, and 4MB, we wouldn't really be saving
anything internally, but wasting time on repeated reads, if the file is long
enough.
Also, don't do the seek if we know we're going to return an error immediately
after.
This should fix reading of any files in /proc, which all have size == 0. In
particular, various files read by coredump might be larger than 32767.
What about /sys? The file there return a fake value, usually 4096. So we'll
allocate a small buffer and read that.
Anita Zhang [Fri, 26 Mar 2021 10:01:38 +0000 (03:01 -0700)]
oomd: make it more clear when a kill happens
Improve the logging to only print if systemd-oomd killed something. And
also print which cgroup was targeted.
Demote general swap above/pressure above messages to debug.
№1 0x00007fb5f13ae87f in selabel_lookup_raw (rec=<optimized out>, con=con@entry=0x7fffef307380, key=key@entry=0x55f616ac4750 "/run/user/1000/systemd/units/invocation:systemd-tmpfiles-clean.service", type=type@entry=40960) at label.c:256
lr = <optimized out>
'rec' is passed through as is to selabel_lookup_common().
№2 0x00007fb5f1561b2d in selinux_create_file_prepare_abspath (abspath=0x55f616ac4750 "/run/user/1000/systemd/units/invocation:systemd-tmpfiles-clean.service", mode=40960) at ../src/basic/selinux-util.c:368
filecon = 0x0
r = <optimized out>
__PRETTY_FUNCTION__ = "selinux_create_file_prepare_abspath"
__func__ = "selinux_create_file_prepare_abspath"
№3 0x00007fb5f1561ec3 in mac_selinux_create_file_prepare (path=<optimized out>, mode=40960) at ../src/basic/selinux-util.c:431
r = 0
abspath = 0x55f616ac4750 "/run/user/1000/systemd/units/invocation:systemd-tmpfiles-clean.service"
__PRETTY_FUNCTION__ = "mac_selinux_create_file_prepare"
We checked label_hnd != NULL, but then we apparently called
avc_netlink_check_nb(), which reset label_hnd. Yay for global state!
№4 0x00007fb5f1549950 in symlink_atomic_label (from=0x55f6169d8b50 "69a8dcf7a7ac46b29306f2fddbed3edc", to=0x55f616ab8380 "/run/user/1000/systemd/units/invocation:systemd-tmpfiles-clean.service") at ../src/basic/label.c:55
r = <optimized out>
__PRETTY_FUNCTION__ = "symlink_atomic_label"
In the logs:
Mar 29 14:48:44 fedorapad.home systemd[1974]: selinux: avc: received policyload notice (seqno=2)
Mar 29 14:48:44 fedorapad.home systemd[1974]: Failed to initialize SELinux labeling handle: No such file or directory
Mar 29 14:48:44 fedorapad.home systemd[1974]: selinux: avc: received policyload notice (seqno=3)
Mar 29 14:48:44 fedorapad.home systemd[1974]: selinux: avc: received setenforce notice (enforcing=0)
Christian Hesse [Sun, 28 Mar 2021 11:00:49 +0000 (13:00 +0200)]
units: make locale directory writable for systemd-localed
With 8f20232fcb52dbe6255f3df6101fc057af90bcfa systemd-localed supports
generating locales when required. This fails if the locale directory is
read-only, so make it writable.
Fangrui Song [Mon, 29 Mar 2021 06:35:06 +0000 (23:35 -0700)]
sd-bus: set retain attribute on BUS_ERROR_MAP_ELF_REGISTER
LLD 13 and GNU ld 2.37 support -z start-stop-gc which allows garbage
collection of C identifier name sections despite the __start_/__stop_
references. Simply set the retain attribute so that GCC 11 (if
configure-time binutils is 2.36 or newer)/Clang 13 will set the
SHF_GNU_RETAIN section attribute to prevent garbage collection.
Without the patch, there are linker errors like the following with -z
start-stop-gc.
```
ld: error: undefined symbol: __start_SYSTEMD_BUS_ERROR_MAP
>>> referenced by bus-error.c:93 (../src/libsystemd/sd-bus/bus-error.c:93)
>>> sd-bus_bus-error.c.o:(bus_error_name_to_errno) in archive src/libsystemd/libsystemd_static.a
```
But it seems that we don't want those calls at all. The test was originally
added with the call in a6ee01caf3409ba9820e8824b9262fbac31a9f77, but I don't
see why we should override this. If the user wants to execute the test with
mempool disabled, we shouldn't ignore that.
basic/fileio: optimize buffer sizes in read_full_virtual_file()
We'd proceed rather inefficiently: the initial buffer size was LINE_MAX/2,
i.e. only 1k. We can read 4k at the same cost.
Also, we'd try to allocate 1025, 2049, 4097 bytes, i.e. always one higher than
the power-of-two size. Effectively the allocation would be bigger, and we'd
waste the additional space. So let's allocate aligned to the power-of-two size.
size=4095, 8191, 16383, so we allocate 4k, 8k, 16k.
basic/fileio: simplify calculation of buffer size in read_full_virtual_file()
We'd first assign a value up to SSIZE_MAX, and then immediately check if we
have a value bigger than READ_FULL_BYTES_MAX. This wasn't exactly wrong, but a
bit roundabout. Let's immediately assign the value from the appropriate range
or error out.
As noted in https://github.com/systemd/systemd/pull/17535#discussion_r534129256,
"raw" is misleading in this context. Let's use a more descriptive term.
ask-password: when querying for a password, try to read from credential store first
This adds generic support for the SetCredential=/LoadCredential= logic
to our password querying infrastructure: if a password is requested by a
program that has a credential store configured via
$CREDENTIALS_DIRECTORY we'll look in it for a password.
The "systemd-ask-password" tool is updated with an option to specify the
credential to look for.
sysusers: read passwords from the credentials logic
Let's make use of our own credentials infrastructure in our tools: let's
hook up systemd-sysusers with the credentials logic, so that the root
password can be provisioned this way. This is really useful when working
with stateless systems, in particular nspawn's "--volatile=yes" switch,
as this works now:
core: when inheriting credentials from manager to service, make missing creds graceful
Let's be a bit less strict when setting up credentials: if the service
manager didn't receieve a cred, and we shall propagate it down via
LoadCredentials= don't fail. Fail on all other errors though, as before,
and on explicitly listed paths.
core: allow omitting second part of LoadCredentials= argument
This allows "LoadCredentials=foo" to be used as shortcut for
"LoadCredentials=foo:foo", i.e. it's a very short way to inherit a
credential under its original name from the service manager into a
service.
mount-util: handle remount failures gracefully if flags already match
In bind_remount_one_with_mountinfo() let's handle mount failures
gracefully if the flags already match anyway. This isn't perfect, since
it mixes up superblock and mount point flags, but it's close enough.
mount-util: fold what we need from get_mount_flags() bind_remount_one_with_mountinfo()
And get rid of get_mount_flags() altogether.
(This drops the statvfs() fallback that get_mount_flags() did. That
fallback was incomplete however, and mostly hid errors. Our primary
avenue to get mount flags is /proc/self/mountinfo and we should trust
it, and fix bugs we might encounter with it, but not tape over it.
Dropping the fallback is relevant in particular as it actually returned
mount flags for any path, not just mount points, which was very icky.)
mount-util: store mount flags in "todo" list in + handle submounts gracefully
This replaces the "todo" set with a "todo" hash map that stores the
mount flags we found. This makes an explicit call to get_mount_flags()
unncessary, since we have the flags handy right-away, and lowers our
work from O(n^2) to O(n). Nice!
The "done" set is also improved slightly: we'll use more modern ways to
allocate it, via set_ensure_consume(), and freeing-via-hash_ops.
Finally, failures on submount remounts are now handled gracefully,
there are just too many reasons why they might fail, given NFS, autofs,
FUSE which weird access controls, where even root might lack the privs
to do something.
mount-util: shortcut things after generating top-level bind mount
Instead of marking the bind mount read-only right-away, let's just
restart the loop, so that we'll pick it up like any other mount and then
remount like that.
Let's always query one property, check it, and then query the next,
preferring "cheap" ones over "slow" ones (i.e. cheap are the ones we can
check directly, and slow are the ones we need to check with some loop of
some kind).
This adds the same line to most of our .conf files.
Not for systemd/user.conf though, since we can't correctly display it right
now:
$ systemd-analyze cat-config --user systemd/user.conf
Option --user is not supported for cat-config right now.
For sysusers.d, tmpfiles.d, rules.d, etc, there is no single file. Maybe
we should short READMEs in /usr/lib/sysusers.d, /usr/lib/tmpfiles.d, etc.?
When following CNAME/DNAME redirects in the stub we currently first
iterate through the packet and pick up what we can use (in
dns_stub_collect_answer_by_question() and friends), following all
CNAMEs/DNAMEs, and would then issue dns_query_process_cname() to move
the DnsQuery object forward too, where we'd then possibly restart
the query and pick things up again, as above.
There's one thought error in this though: dns_query_process_cname()
tries to be smart and will internally follow not just a single
CNAME/DNAME redirect, but a chain of them if they are contained inside
the same packet until we reach the point where the answer is not
included in the packet anymore, where we'd restart the query. This was
great as long as we only focussed on the D-Bus and Varlink resolver
APIs, since there the CNAME/DNAME chain in the middle doesn't actually
matter, we just return information about the final name of the RR and
its content, and aren't interested in the chain to it. For the DNS stub
this is different however: there we need to place the full CNAME/DNAME
chain (and all the appropriate metadata RRs) in the stub reply.
Hence rework this so that we build on the fact that the previous commit
split dns_query_process_cname() in two:
1. dns_query_process_cname_one() will do exactly one CNAME/DNAME
redirect step. This will be called by the stub, so that we can pick
up matching RRs for every single step along the way.
2. dns_query_process_cname_many() will follow a chain as long as that's
possible within the same packet. It's thus pretty much identical to
the old dns_query_process_cname() call. This is what we now use in
the D-Bus and Varlink APIs. dns_query_process_cname_many() is
basically just a loop around dns_query_process_cname_one().
Any logic to follow and pick up RRs manually in the stub along the
CNAME/DNAME path is now dropped (i.e.
dns_stub_collect_answer_by_question() becomes trivially simple again),
we solely rely on dns_query_process_cname_one() to follow CNAME/DNAME
now: each step followed by a full call of dns_stub_assign_sections() to
copy out the RRs that matter.
Net result: things are a bit simpler again, as the only place we follow
CNAME/DNAME redirects is DnsQuery again, and stub answers are always
complete: they contain all CNAME/DNAME RRs on the way including all
their metadata we might pick up in the other sections.
resolved: split dns_query_process_cname() into two separate functions
This does some refactoring: the dns_query_process_cname() function
becomes two: dns_query_process_cname_one() and
dns_query_process_cname_many(). The former will process exactly one
CNAME chain element, the latter will follow a chain for as long as
possible within the current packet.
dns_query_process_cname_many() is mostly identical to the old
dns_query_process_cname(), and all existing code is moved over to using
that.
This is mostly preparation for the next commit, where we make direct use
of dns_query_process_cname_one().
This also renames the DNS_QUERY_RESTARTED return value to
DNS_QUERY_CNAME. That's because in the dns_query_process_cname_many()
case as before if we return this we restarted the query in case we
reached the end of the chain without a conclusive answer, as before. But
in dns_query_process_cname_one() we'll only go one step anyway, and
leave restarting if needed to the caller. Hence DNS_QUERY_RESTARTED is a
bit of a misnomer in that case.
This also gets rid of the weird tail recursion in
dns_query_process_cname() and replaces it with an explicit loop in
dns_query_process_cname_many(). The old recursion wasn't a security
issue since we put a limit on the number of CNAMEs we follow anyway, but
it's still icky to scale stack use by that.
Luca Boccassi [Thu, 25 Mar 2021 11:47:13 +0000 (11:47 +0000)]
test-dhcp6-client: add one more assert on memory mapping
Static analyzers need a hint that optval is not pointing
off the end of the msg_advertise array, since pos can go
up to the full length of it. The array is manually
constructed so we know this won't happen, but adding one
more assert should be enough to avoid false positives.
Previously we'd stick all answer sections RRs we acquired into
the authoritative section if we didn't find them directly answering our
question. Let's put them into additional instead. The authoritative
section should hence only include what comes from the upstream
authoritative section, and nothing else.
resolved: pass mDNS reply packets to each transaction exactly once
Previously we'd iterate through the RRs of an mDNS reply and then find
exactly one matching transaction on our scope for it, and pass it as
reply to that. If multiple RRs of the same packet match we'd pas the
packet multiple times to the transaction even.
This all doesn't really work anymore since there can be multiple open
transactions for the same key (with different flags), and it's kinda
ugly anywy. Hence let's turn this around: let's iterate through the
transactions and check if any of the included RRs match it, and if so
pass the packet to that transaction exactly once.
This speeds up mDNS a bit, since previously we'd oftentimes fail to find
all suitable transactions for an mDNS reply (because there can be
multiple transactions for the same RR key with different flags, and we
checked exactly one flag combination). Which would then mean the
transaction would time out, and be retried – at which point the cache
would be populated and thus it would still succeed, but only after this
timeout. With this fix this is corrected: every transaction that matches
will get the reply, instantly as we get it.
resolved: upgrade log level to LOG_NOTICE if we switch to fallback server (or back)
This is inspired by a recent thread on fedora-devel: it's noteworthy
when we switch to the fallback servers, since it might (or might not)
indicate some configuration problem.
David Tardon [Wed, 24 Mar 2021 13:45:02 +0000 (14:45 +0100)]
local-addresses: fix use of uninitialized value
This can happen if ifi fails to be read from the netlink message and the
error is ENODATA.
Fixes the following valgrind message when running netstat:
==164141== Conditional jump or move depends on uninitialised value(s)
==164141== at 0x524AE60: address_compare (local-addresses.c:29)
==164141== by 0x48BCC78: msort_with_tmp.part.0 (msort.c:105)
==164141== by 0x48BC9E4: msort_with_tmp (msort.c:45)
==164141== by 0x48BC9E4: msort_with_tmp.part.0 (msort.c:53)
==164141== by 0x48BCF85: msort_with_tmp (msort.c:45)
==164141== by 0x48BCF85: qsort_r (msort.c:297)
==164141== by 0x52500FC: UnknownInlinedFun (sort-util.h:47)
==164141== by 0x52500FC: local_gateways.constprop.0 (local-addresses.c:310)
==164141== by 0x5251C05: _nss_myhostname_gethostbyaddr2_r (nss-myhostname.c:456)
==164141== by 0x5252006: _nss_myhostname_gethostbyaddr_r (nss-myhostname.c:500)
==164141== by 0x498E7FE: gethostbyaddr_r@@GLIBC_2.2.5 (getXXbyYY_r.c:274)
==164141== by 0x498E560: gethostbyaddr (getXXbyYY.c:135)
==164141== by 0x121353: INET_rresolve.constprop.0 (inet.c:212)
==164141== by 0x1135B9: INET_sprint (inet.c:261)
==164141== by 0x121BFC: addr_do_one.constprop.0.isra.0 (netstat.c:1156)
Anita Zhang [Tue, 23 Mar 2021 07:49:28 +0000 (00:49 -0700)]
process-util: dont allocate max length to read /proc/PID/cmdline
Alternative title: Replace get_process_cmdline()'s fopen()/fread() with
read_full_virtual_file().
When RLIMIT_STACK is set to infinity:infinity, _SC_ARG_MAX will
return 4611686018427387903 (depending on the system, but definitely
something larger than most systems have). It's impractical to allocate this
in one go when most cmdlines are much shorter than that.
Instead use read_full_virtual_file() which seems to increase the buffer
depending on the size of the contents.
projects / thirdparty / systemd.git / log
