Since the new functionality is controlled by an option, this causes no change
in output yet, except tests.
The login in the old branch of !(flags & PROCESS_CMDLINE_QUOTE) is essentially
unmodified. But there is an important difference in behaviour: instead of
unconditionally reading the whole virtual file, we now read only 'max_columns'
bytes. This makes out code to write process lists quite a bit more efficient
when there are processes with long command lines.
So far we would append "…" or "..." when the string was wider than the specified
output width. But let's add a mode where the caller knows that the string being
passed is already truncated.
The condition for jumping back in utf8_escape_non_printable_full() was
off-by-one. But we only jumped to that label after doing a check with a
stronger condition, so I think it didn't matter. Now it matters because we'd
output the forced ellipsis one column too early.
The comment in the code said that so far this didn't matter, but I want to use
shell quoting in more places where this will make a difference. So control
characters are now escaped. Normal utf-8 characters are passed through, it
is 2021 after all and pretty much everyone is (or should be) using utf-8.
While touching the code, change 'char *r' → 'char *buf', in line with modern
style.
shell_escape() is mostly used for mount paths and similar, where we assume
no newlines are present in the string. But if any were ever present, we
should escape them. So let's simplify the code by making this unconditional.
I want to tweak behaviour further, and that'll be easier when "style"
is converted to a bitfield.
Some callers used ESCAPE_BACKSLASH_ONELINE, and others not. But the
ones that didn't, simply didn't care, because the argument was assumed to
be one-line anyway (e.g. a service name). In environment-generator, this
could make a difference. But I think it's better to escape the newlines
there too. So newlines are now always escaped, to simplify the code and
the test matrix.
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.
https://bugzilla.redhat.com/show_bug.cgi?id=1944171
This was in F33, systemd-246.13, but the logic in the code didn't change.
Thread 1 (Thread 0x7fb5f0341b80 (LWP 1974)):
№0 selabel_lookup_common (rec=0x0, translating=0, key=0x55f616ac4750 "/run/user/1000/systemd/units/invocation:systemd-tmpfiles-clean.service", type=40960) at label.c:167
'rec' is the handle that we passed.
№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)
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.
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.
Coverity CID#1450973.
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.
This follows up on 0b1f3c768c, adding more places
where we should reopen the log after forking with FORK_CLOSE_ALL_FDS.
When immediately calling exec in the child, prefer to explicitly reopen the log
after exec fails. In other cases, just use FORK_REOPEN_LOG.
Commit 0b1f3c768c has introduced log_open()
calls after exec fails post-fork. However, the log_open() call itself could
change the value of errno, which, for me, manifested in:
$ coredumpctl gdb
...
Failed to invoke gdb: Success
Fix this by using PROTECT_ERRNO in log_open().
We aren't interested in the data previousl read, hence free() followed
by malloc() is typically better since it means libc doesn't have to
restore the contained data needlessly.
Wherever we read virtual files we better should use
read_full_virtual_file(), to make sure we get a consistent response
given how weird the kernel's handling with partial read on such file
systems is.
When the test suite is being run in a foreign environment,
/sys/fs/cgroup might not be set up in a way that we recognize.
Returning ENOMEDIUM causes the tests to be skipped in this case.
Bug: https://bugs.gentoo.org/771819
With EXTRACT_UNESCAPE_SEPARATORS, backslash is used to escape the separator.
But it wasn't possible to insert the backslash itself. Let's allow this and
add test.
A test for stripping of escaped backslashes without any flags was explicitly
added back in 4034a06ddb. So it seems to be on
purpose, though I would say that this is at least surprising and hence deserves
a comment.
In test-extract-word, add tests for standalone EXTRACT_UNESCAPE_SEPARATORS.
Only behaviour combined with EXTRACT_CUNESCAPE was tested.
So Linux has this (insane — in my opinion) "feature" that if you name a
network interface "foo%d" then it will automatically look for the
interface starting with "foo…" with the lowest number that is not used
yet and allocates that.
We should never clash with this "magic" handling of ifnames, hence
refuse this, since otherwise we never know what the name is we end up
with.
We should probably switch things from a deny list to an allow list
sooner or later and be much stricter. Since the kernel directly enforces
only very few rules on the names, we'd need to do some research what is
safe and what is not first, though.
This fixes two checks where we compare string sizes when validating with
FILENAME_MAX. In both cases the check apparently wants to check if the
name fits in a filename, but that's not actually what FILENAME_MAX can
be used for, as it — in contrast to what the name suggests — actually
encodes the maximum length of a path.
In both cases the stricter change doesn't actually change much, but the
use of FILENAME_MAX is still misleading and typically wrong.
