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Signed-off-by: Ross Burton <ross.burton@arm.com>
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Newer versions of glibc have a lchmod function which we need to wrap.
Add this, and tweak fchmodat to be able to handle the "no symlink
resolution" case rather than duplicate code.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Similar to mkstemp64 when oflags=0, therefore move the wrapper and call
from mkstemp64. Note that some glibc versions would have one but not the other
so ensure fall back to the real function is correct on those versions.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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There is magic in the posts where specific variable names have specific
magic. For that magic to work, "path" needs to be used not "pathname" as
is currently there. Fix this, which fixes path issues on systems using
statx (Ubuntu 20.04 in particular).
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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In the xattr handling functions, if result is NULL, which it can be
with the path ignore code, there is a NULL pointer dereference and
segfault. Everywhere else checks result first, this appears to just
be an omission.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Consider what happens if a program does:
fd = fopen("A")
link("A", "B")
unlink("A")
fchown(fd)
Assuming we can't use the database, in order to handle this correctly,
we need to change the open fd to point at B when A us unlinked.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Currently, pseudo considers any path accessed whist its running to be
a valid entry to track in its database. The way OpenEmbedded uses pseudo,
there are paths we care about accesses to from a pseudo perspective and paths
which we simply don't care about.
This patch adds a PSEUDO_IGNORE_PATHS environment variable which is a comma
separated list of path prefixes to ignore accesses to.
To do this, we add some functions which can check a path argument or a file
descriptor argument and use these in the pseudo wrappers where path or fd
arguments are present. Where paths are being ignored, we skip straight to
the underlying real function.
Psuedo needs to keep track of the open fd mappings to files so we still need
to allow those cases into the pseudo_op function. Specficially this means
OP_CLOSE, OP_OPEN, OP_DUP and OP_CHDIR.
Apart from OP_OPEN which could call the server, the other operations are client
side only so passed through. We 'tag' the functions using these operations so
that the path ignore code isn't triggered. For OP_OPEN we exit early and skip
the server op. We also have a catch all in client_op to ensure any operatings
we didn't manage to skip early still get skipped correctly.
OP_CHROOT is a special case. Where ignored path prefixes are used as a chroot,
for the lifetime of the chroot, the path is effectively dropped from the
PSEUDO_IGNORE_PATHS list. Whilst slightly counter intuaitive, this turned out
to be the most effective way to do things due to commands like useradd and
their use of chroots.
For sqlite3 and appropriate path filtering in OE, this took the database from
45,000 entries to about 180. For dbus this was 88,000 down to 760. Given the
number of client to server trips these numbers of paths involves, the win
is seemingly worthwhile.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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The pseudo rename guts test for an item being renamed to
itself, only after information about it has been deleted.
We move the test to before we play with the database.
Note that pseudo does not support renameat2().
Signed-off-by: Joe Slater <joe.slater@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Linux 3.15 and newer introduced new open file description locks.
Currently pseudo prints a warning if fcntl is used with OFD locks:
unknown fcntl argument 37, assuming long argument.
However, calls to fcntl with a OFC lock set need a struct flock
pointer. Treat F_OFD_GETLK (and friends) like F_GETLK (and friends).
This issue has been observed with ostree. Comparing strace output
between two runs with/without this patch shows the same fcntl calls,
hence it seems not to matter in practice.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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The file mode was accidentally overwritten with only the permission
bits, causing the server to falsely assume that the database was
corrupted (because the msg_header.mode did not contain S_IFDIR
anymore) even though it was the client doing the corruption.
In practice that had the effect of leaking the UID of the user, into
the pseudo environment.
This fixes Bug 13959 -- https://bugzilla.yoctoproject.org/show_bug.cgi?id=13959
Signed-off-by: Johannes Beisswenger <johannes.beisswenger@cetitec.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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pseudo: ENOSYS for 'fsetxattr'.
which was being caused by dlsym() for that function returning NULL. This
appears to be due to it finding an unresolved symbol in libacl for this
symbol in libattr. It hasn't been resolved so its NULL. dlerror() returns
nothing since this is a valid symbol entry, its just not the one we want.
We can add the glibc version string for the symbol we actually want so we get
that version rather than the libattr/libacl one.
To quote libattr:
"""
These dumb wrappers are for backwards compatibility only.
Actual syscall wrappers are long gone to libc.
"""
and they are simply wrappers around the libc version so our attaching
to the libc versions should intercept any accesses via these too.
RP 2020/06/22
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org
Upstream-Status: Pending [discussed with seebs on irc and appears the correct fix]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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seccomp. Therefore intercept the seccomp syscall and alter it, pretending that
seccomp was setup when in fact we do nothing. If we error as unsupported,
utilities like file will exit with errors so we can't just disable it.
Also, it fails to compile pseudo-native on centos 7:
| ports/linux/pseudo_wrappers.c: In function ‘prctl’:
| ports/linux/pseudo_wrappers.c:129:14: error: ‘SECCOMP_SET_MODE_FILTER’ undeclared (first use in this function)
| if (cmd == SECCOMP_SET_MODE_FILTER) {
| ^
Add macro guard for seccomp to avoid the failure.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Latest versions of attr have removed the xattr.h header,
with the rationale that libc is providing the same wrappers.
attr/attributes.h is providing the ENOATTR definition.
Upstream-Status: Pending
Signed-off-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Linux system's realpath() remove trailing slashes, but pseudo's doesn't, need
make them identical.
E.g., the following code (rel.c) prints '/tmp' with system's realpath, but
pseudo's realpath prints '/tmp/':
#include <stdio.h>
#include <limits.h>
#include <stdlib.h>
int main() {
char out[PATH_MAX];
printf("%s\n", realpath("/tmp/", out));
return 0;
}
$ bitbake base-passwd -cdevshell # For pseudo env
$ gcc rel.c
$ ./a.out
/tmp/ (but should be /tmp)
This patch fixes the problem.
Upstream-Status: Submitted [https://lists.yoctoproject.org/g/poky/message/11879]
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Modern distros (e.g. fedora30) are starting to use the new statx() syscall through
the newly exposed glibc wrapper function in software like coreutils (e.g. the ls
command). Add support to intercept this to pseudo.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Upstream-Status: Submitted [Emailed to seebs]
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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When statting a file that we may or may not be opening with O_NOFOLLOW,
we should use lstat (or AT_SYMLINK_NOFOLLOW) to try to get information
about the right file.
Also when we want to check whether a bit is set, we should use & rather
than |. I am an experienced programmer and know the difference between
those.
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Did you know that, similar to AT_SYMLINK_NOFOLLOW, there's
an O_NOFOLLOW available in flags for open/openat?
I didn't.
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This adds SPDX license headers to all source files in pseudo so license
identification models current best practise.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Clean up the "unused parameter" warnings in renameat2.
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This is a heck of a special case: If you call open on a FIFO/pipe,
and you didn't have O_NONBLOCK, and you used O_RDONLY or O_WRONLY,
but not O_RDWR, the open can block forever. Unfortunately, pseudo
assumes syscalls complete. We attempt to drop the lock and restore
our state, then recover it later.
Why? Because the .NET runtime does this for a debug hook.
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So renameat2 now has a glibc wrapper in some recent glibc, which
means that mv can use it, and thus bypass all our clever testing,
and since we can't intercept the actual syscall (gnulib's implementation
apparently doesn't hit the glibc syscall() wrapper?), this results
in files being moved without pseudo knowing about them.
Implementing the semantics properly is Very Hard, but possibly we
can just fail politely for now.
We'll be back to this later.
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openat() was passing its flags unaltered to pseudo_root_path(), which
assumes that a flags argument other than 0 means "don't follow symlinks
in last path component". This is completely wrong, and I have no idea
how it survived this long unnoticed.
Now, if a plain flags variable is set and not overruled by a
comment like /* flags=... */, it's masked with AT_SYMLINK_NOFOLLOW,
as there are other values fstatat() and friends can take, and the
openat() flags are just overridden with 0. (The only meaningful case
would be O_NOFOLLOW, but O_NOFOLLOW instructs us to *fail* in the
open if the path is a symlink, so we don't care.)
Signed-off-by: Seebs <seebs@seebs.net>
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But what if syscall(2) was the *first* function with a wrapper
that you called?
Also reduced amount of argument-copying in syscall(2), on further
study, anything with off_t arguments has less than 6 arguments
by enough to keep the total argument count down.
Signed-off-by: Seebs <seebs@seebs.net>
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is followed by setxattr(); previously it was the other way around. This
broke pseudo when a copied directory has one of the special
bits (setuid, setgid, sticky) set; the special bit wound up getting
removed.
Root cause is that ACLs never included special bits in the first place,
so we need to merge them back in ourselves.
[YOCTO #12379]
Signed-off-by: Richard Tollerton <rich.tollerton@ni.com>
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This wrapper should allow us to reject renameat2 attempts by
coreutils, letting us regain functionality on FC27 and related
systems.
This is not safe/portable/etc even by pseudo's standards, and
arguably it should be a separate and optional port.
[Amended commit: Don't include the dodgy renameat2 wrapper
which it turns out we'd never hit anyway.]
Signed-off-by: Seebs <seebs@seebs.net>
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The mkostemps() family are all bad but people use them so here we
are. Since mkstemp(), mkstemps(), and mkostemp() can all be
implemented by calling mkostemps() with additional zeroes passed
in, do it that way.
Signed-off-by: Seebs <seebs@seebs.net>
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O_TMPFILE is, on at least one system, (__O_TMPFILE | O_DIRECTORY),
so (flags & O_TMPFILE) can be non-zero even when O_TMPFILE was not set.
Signed-off-by: Seebs <seebs@seebs.net>
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Whoops, missed this one. Reported/submitted by
<joshua.g.lock@linux.intel.com>.
Signed-off-by: Seebs <seebs@seebs.net>
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Patch was submitted by <dan.dedrick@gmail.com>, revised to make it
a subport in case someone cares about a Linux system which doesn't
have this function. (Which is probably unlikely, but I am a cautious
sort.)
Signed-off-by: Seebs <seebs@seebs.net>
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This allows the pseudo /etc/group to contain extremely long lines,
e.g. when a group has a lot of members. Without this, chown and
chgrp fail for group names that occur after such long lines.
Signed-off-by: Zoltán Böszörményi <zboszor@pr.hu>
Signed-off-by: Seebs <seebs@seebs.net>
---
ports/darwin/guts/getgrouplist.c | 54 +++++++++++++++++++++++++++-----------
ports/linux/guts/getgrouplist.c | 54 +++++++++++++++++++++++++++-----------
ports/uids_generic/guts/getgrent.c | 26 +++++++++++++++---
ports/uids_generic/guts/getgrgid.c | 26 +++++++++++++++---
ports/uids_generic/guts/getgrnam.c | 25 +++++++++++++++---
5 files changed, 146 insertions(+), 39 deletions(-)
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This is a rework which replaces a previous patch. In this version,
files created with O_TMPFILE don't get recorded in the database
at all, but if we get a link request for /proc/self/fd/N, and the
corresponding file is not in the database, we send a CREAT request
for it instead of a LINK, and that appears to work with a MUCH
reduced chance of database leakage.
Also the O_TMPFILE won't be creating bogus database entries
anymore.
Signed-off-by: Seebs <seebs@seebs.net>
linkat fix
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Based on a submission from Anton Gerasimov <anton@advancedtelematic.com>
On some systems, with some kernel configs, "cp -a" apparently tries to
set an empty ACL list, with a valid header but no contents, which causes
strange and mysterious behavior later if we actually create such an entry.
So filter that out, also sanity-check a couple of other things.
Signed-off-by: Seebs <seebs@seebs.net>
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file. Before setting a file's capabilities with cap_set_file() (which uses
setxattr()) it calls cap_set_flag(mycaps, CAP_EFFECTIVE, 1, &capflag,
CAP_SET). cap_set_flag() uses the capset syscall to raise the process'
effective capability. In most cases if the process isn't running as root
this will fail and setcap will exit with an error. Because setxattr is
intercepted by pseudo it's unnecessary for setcap to call capset().
Override capset with a pseudo function that does nothing and always
returns 0.
Signed-off-by: George McCollister <george.mccollister at gmail.com>
Signed-off-by: Seebs <seebs@seebs.net>
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x32 compilation fails because x32 defines __amd64__ and thus pseudo tries
to grab a version of memcpy that's useful for amd64, and this isn't
available. Try disabling that, see what happens.
Signed-off-by: Seebs <seebs@seebs.net>
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There was a bug in rename(), which was duplicated when renameat() was
implemented, and which got fixed two years ago for rename(), but no
one ever uses renameat() so it didn't get fixed there. Thanks
to Anton Gerasimov <anton@advancedtelematic.com> for the bug report
and patch.
Signed-off-by: Seebs <seebs@seebs.net>
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Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
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So a recent change to ld.so behavior revealed that pseudo was not
always correctly detecting that a function hadn't been found by the
RTLD_NEXT search. This only happened for functions which genuinely
didn't exist and wouldn't get called (like mknod on Linux, which
is actually always done as an inline function that calls __xmknod),
but when the diagnostics started showing up, it broke things. Fix it
so the diagnostics would have shown up when things were originally
broken, also fix the resulting diagnostics.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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Since the pseudo socket is actually created by a call to bind, the
bind call could create a file, which means it needs to record a
database entry.
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So we had this really strange problem where, sometimes but not always,
pseudo would have strange problems on startup, where the pseudo server
would end up running under pseudo. And this produced the most fascinating
thing, which was:
unsetenv("LD_PRELOAD");
assert(getenv("LD_PRELOAD") == NULL);
for (int i = 0; environ[i]; ++i) {
assert(strncmp(environ[i], "LD_PRELOAD=", 11));
}
(pseudocode untested)
This would crash on the environ search. Because getenv() was not searching
environ.
WHAT.
So it turns out, *bash overrides getenv, setenv, and so on*. Under those
names. Hiding the glibc ones. And this creates horrible problems if you
assumed that your code could call those functions and expect them to work.
So as a workaround, pseudo now uses dlsym to find getenv, etc., from
glibc, and invokes those directly if possible. Also the client now uses
unwrapped fork/exec for spawning the server, which cleans up the
behavior of that code quite a bit.
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Server process now waits for its forked child when daemonizing, allowing
us to yield meaningful exit status. Lock is now taken by the child, since
it has a way to tell the parent about the exit status. (We send SIGUSR1 to
the server to cause the wait loop to stop when the client is ready to go.)
This allows us to switch to fcntl locking, which should in theory allow us
to run with the pseudo directory NFS-mounted. Woot!
Also mark a couple of overly spammy messages as PDBGF_VERBOSE to reduce the
volume of uninteresting dup spam when looking at client behaviors.
Client now uses execve to spawn server to work around a very strange behavior
of unsetenv.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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mknod(2) automatically defaults to S_IFREG if not given an explicit
file type, so pseudo should too. Otherwise, GNU tar can (for some
reason, it mostly does this when extracting xattrs?) invoke mknod
instead of open with O_CREAT to create a file, and just provide the
permission bits, and pseudo creates a "weird file" with no type bits
in the database, which is unhelpful.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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The f{re,}open{64,} functions use a default mode of 0666 & ~umask,
and defaulting to 0600 for the post-open chmod was breaking some use
cases. Problem and solution identified by Ross Burton, I just made the
local copy of the patch.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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mkdirat() was calling real_fchmodat with invalid arguments (it turns
out that AT_SYMLINK_NOFOLLOW is both irrelevant and forbidden by Linux),
and the wrapper function did not restore errno to its previous value.
This breaks localedef, because localedef is unconditionally storing
the value of errno after a mkdir *whether or not the mkdir failed*,
which is almost certainly wrong. Similar issue with mkfifoat.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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There's some changes to allow things to work even if umask is 0700;
originally this was just regarded as a broken state, but it became
necessary to fix it in order for the xattrdb code to work, only the
fix could result in files having a raw filesystem mode that lacked
execute bits it should have had.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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When I trimmed the spurious free()s for the new lower-allocation
path strategy, I forgot to look for cases where I was relying on
the allocation, such as realpath(path, NULL).
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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gcc is better about warnings and spotted variables being assigned but
not used. Clever gcc. Cleaned up the old bits.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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When xattr emulation is used to store extended attributes, dummy
entries get made in the db using whatever UID/GID were in the real
stat buffer if no entry already existed. Change these to -1, and
treat -1 uid/gid as a missing entry for stat purposes.
xattrdb was not merging existing uid/gid values. Change this by
loading existing values to merge them in when executing chown/chmod
commands.
Newly-created files could end up with a filesystem mode of 0 if
you used umask, but this breaks xattrdb.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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Dropping the alloc from file paths meant that pseudo_exec_path
could end up just returning its original argument, which was
const-qualified, meaning its return should also be const-qualified.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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This is a moderately experimental feature which stores values in an
extended attribute called 'user.pseudo_data' instead of in the database.
Still missing: Database<->filesystem synchronization for this.
For at least some workloads, this can dramatically improve performance.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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Instead of allocating (and then freeing) these paths all the time,
use a rotating selection of buffers of fixed but probably large enough
size (the same size that would have been the maximum anyway in
general). With the exception of fts_open, there's no likely way to
end up needing more than two or three such paths at a time. fts_open
dups the paths since it could have a large number and need them for
a while. This dramatically reduces (in principle) the amount of allocation
and especially reallocation going on.
Signed-off-by: Peter Seebach <peter.seebach@windriver.com>
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Ross Burton
Richard Purdie
Joe Slater
Stefan Agner
Johannes Beisswenger
Alexander Kanavin
Robert Yang
Seebs
Joshua Lock
Peter Seebach