read(2), write(2), dup(2), and mmap(2). This auditing is not
required by the Common Criteria (and hence was not being
performed), but is valuable in both contemporary live analysis
and forensic use cases.
MFC after: 3 days
Sponsored by: DARPA, AFRL
data (headers). Historically the size of the headers was not checked
against the socket buffer space. Application could easily overcommit the
socket buffer space.
With the new sendfile (r293439) the problem remained, but a KASSERT was
inserted that checked that amount of data written to the socket matches
its space. In case when size of headers is bigger that socket space,
KASSERT fires. Without INVARIANTS the new sendfile won't panic, but
would report incorrect amount of bytes sent.
o With this change, the headers copyin is moved down into the cycle, after
the sbspace() check. The uio size is trimmed by socket space there,
which fixes the overcommit problem and its consequences.
o The compatibility handling for FreeBSD 4 sendfile headers API is pushed
up the stack to syscall wrappers. This required a copy and paste of the
code, but in turn this allowed to remove extra stack carried parameter
from fo_sendfile_t, and embrace entire compat code into #ifdef. If in
future we got more fo_sendfile_t function, the copy and paste level would
even reduce.
Reviewed by: emax, gallatin, Maxim Dounin <mdounin mdounin.ru>
Tested by: Vitalij Satanivskij <satan ukr.net>
Sponsored by: Netflix
- Mark AIO system calls as STD and remove the helpers to dynamically
register them.
- Use COMPAT6 for the old system calls with the older sigevent instead of
an 'o' prefix.
- Simplify the POSIX configuration to note that AIO is always available.
- Handle AIO in the default VOP_PATHCONF instead of special casing it in
the pathconf() system call. fpathconf() is still hackish.
- Remove freebsd32_aio_cancel() as it just called the native one directly.
Reviewed by: kib
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D5589
The filedesc lock is only needed if ioctls caps are present, which is a
rare situation. This is a step towards reducing the scope of the filedesc
lock.
Coredump notes depend on being able to invoke dump routines twice; once
in a dry-run mode to get the size of the note, and another to actually
emit the note to the corefile.
When a note helper emits a different length section the second time
around than the length it requested the first time, the kernel produces
a corrupt coredump.
NT_PROCSTAT_FILES output length, when packing kinfo structs, is tied to
the length of filenames corresponding to vnodes in the process' fd table
via vn_fullpath. As vnodes may move around during dump, this is racy.
So:
- Detect badly behaved notes in putnote() and pad underfilled notes.
- Add a fail point, debug.fail_point.fill_kinfo_vnode__random_path to
exercise the NT_PROCSTAT_FILES corruption. It simply picks random
lengths to expand or truncate paths to in fo_fill_kinfo_vnode().
- Add a sysctl, kern.coredump_pack_fileinfo, to allow users to
disable kinfo packing for PROCSTAT_FILES notes. This should avoid
both FILES note corruption and truncation, even if filenames change,
at the cost of about 1 kiB in padding bloat per open fd. Document
the new sysctl in core.5.
- Fix note_procstat_files to self-limit in the 2nd pass. Since
sometimes this will result in a short write, pad up to our advertised
size. This addresses note corruption, at the risk of sometimes
truncating the last several fd info entries.
- Fix NT_PROCSTAT_FILES consumers libutil and libprocstat to grok the
zero padding.
With suggestions from: bjk, jhb, kib, wblock
Approved by: markj (mentor)
Relnotes: yes
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D3548
Originally it was added in order to prevent trashing of objects with
INVARIANTS enabled. The same effect is now provided with mere UMA_ZONE_NOFREE.
This reverts r286921.
Discussed with: kib
zero. The file_zone if no-free, but r284861 added trashing of the
freed memory. Most visible manifestation of the issue were 'memory
modified after free' panics for the file zone, triggered from
falloc_noinstall().
Add UMA_ZONE_ZINIT flag to turn off trashing. Mjg noted that it makes
sense to not trash freed memory for any non-free zone, which will be
done later.
Reported and tested by: pho
Discussed with: mjg
Sponsored by: The FreeBSD Foundation
falloc_noinstall() followed by finstall() allows you to create and
install file descriptors with custom capabilities. Add falloc_caps()
that can do both of these actions in one go.
This will be used by CloudABI to create pipes with custom capabilities.
Reviewed by: mjg
Summary:
In a runtime that is purely based on capability-based security, there is
a strong emphasis on how programs start their execution. We need to make
sure that we execute an new program with an exact set of file
descriptors, ensuring that credentials are not leaked into the process
accidentally.
Providing the right file descriptors is just half the problem. There
also needs to be a framework in place that gives meaning to these file
descriptors. How does a CloudABI mail server know which of the file
descriptors corresponds to the socket that receives incoming emails?
Furthermore, how will this mail server acquire its configuration
parameters, as it cannot open a configuration file from a global path on
disk?
CloudABI solves this problem by replacing traditional string command
line arguments by tree-like data structure consisting of scalars,
sequences and mappings (similar to YAML/JSON). In this structure, file
descriptors are treated as a first-class citizen. When calling exec(),
file descriptors are passed on to the new executable if and only if they
are referenced from this tree structure. See the cloudabi-run(1) man
page for more details and examples (sysutils/cloudabi-utils).
Fortunately, the kernel does not need to care about this tree structure
at all. The C library is responsible for serializing and deserializing,
but also for extracting the list of referenced file descriptors. The
system call only receives a copy of the serialized data and a layout of
what the new file descriptor table should look like:
int proc_exec(int execfd, const void *data, size_t datalen, const int *fds,
size_t fdslen);
This change introduces a set of fd*_remapped() functions:
- fdcopy_remapped() pulls a copy of a file descriptor table, remapping
all of the file descriptors according to the provided mapping table.
- fdinstall_remapped() replaces the file descriptor table of the process
by the copy created by fdcopy_remapped().
- fdescfree_remapped() frees the table in case we aborted before
fdinstall_remapped().
We then add a function exec_copyin_data_fds() that builds on top these
functions. It copies in the data and constructs a new remapped file
descriptor. This is used by cloudabi_sys_proc_exec().
Test Plan:
cloudabi-run(1) is capable of spawning processes successfully, providing
it data and file descriptors. procstat -f seems to confirm all is good.
Regular FreeBSD processes also work properly.
Reviewers: kib, mjg
Reviewed By: mjg
Subscribers: imp
Differential Revision: https://reviews.freebsd.org/D3079
Previously several places were doing it on its own, partially
incorrectly (e.g. without the filedesc locked) or even actively harmful
by populating jdir or assigning rootvnode without vrefing it.
Reviewed by: kib
- make mode enum start from 0 so that the assertion covers all cases [1]
- rename prefix _CLOEXEC flag with _FLAG
- postpone fhold on the old file descriptor, which eliminates the need to fdrop
in error cases.
- fixup FDDUP_FCNTL check missed in the previous commit
This removes 'fp == oldfde->fde_file' assertion which had little value. kern_dup
only calls fd-related functions which cannot drop the lock or a whole lot of
races would be introduced.
Noted by: kib [1]
All of the CloudABI system calls that operate on file descriptors of an
arbitrary type are prefixed with fd_. This change adds wrappers for
most of these system calls around their FreeBSD equivalents.
The dup2() system call present on CloudABI deviates from POSIX, in the
sense that it can only be used to replace existing file descriptor. It
cannot be used to create new ones. The reason for this is that this is
inherently thread-unsafe. Furthermore, there is no need on CloudABI to
use fixed file descriptor numbers. File descriptors 0, 1 and 2 have no
special meaning.
This change exposes the kern_dup() through <sys/syscallsubr.h> and puts
the FDDUP_* flags in <sys/filedesc.h>. It then adds a new flag,
FDDUP_MUSTREPLACE to force that file descriptors are replaced -- not
allocated.
Differential Revision: https://reviews.freebsd.org/D3035
Reviewed by: mjg
Use the same scheme implemented to manage credentials.
Code needing to look at process's credentials (as opposed to thred's) is
provided with *_proc variants of relevant functions.
Places which possibly had to take the proc lock anyway still use the proc
pointer to access limits.
The point of this is to be able to add RACCT (with RACCT_DISABLED)
to GENERIC, to avoid having to rebuild the kernel to use rctl(8).
Differential Revision: https://reviews.freebsd.org/D2369
Reviewed by: kib@
MFC after: 1 month
Relnotes: yes
Sponsored by: The FreeBSD Foundation
strings returned to userland include the nulterm byte.
Some uses of sbuf_new_for_sysctl() write binary data rather than strings;
clear the SBUF_INCLUDENUL flag after calling sbuf_new_for_sysctl() in
those cases. (Note that the sbuf code still automatically adds a nulterm
byte in sbuf_finish(), but since it's not included in the length it won't
get copied to userland along with the binary data.)
Remove explicit adding of a nulterm byte in a couple places now that it
gets done automatically by the sbuf drain code.
PR: 195668
Introduce fget_fcntl which performs appropriate checks when needed.
This removes a branch from fget_unlocked.
Introduce fget_mmap dealing with cap_rights_to_vmprot conversion.
This removes a branch from _fget.
Modify fget_unlocked to pass sequence counter to interested callers so
that they can perform their own checks and make sure the result was
otained from stable & current state.
Reviewed by: silence on -hackers
We obtain a stable copy and store it in local 'fde' variable. Storing another
copy (based on aforementioned variable) does not serve any purpose.
No functional changes.
The only potential in-tree consumer (_fdrop) special-cased it and returns 0
0 on its own instead of calling badfo_close.
Remove the special case since it is not needed and very unlikely to encounter
anyway.
No objections from: kib
Not all consumers providing fdp to copy from want files.
Perhaps these functions should be reorganized to better express the outcome.
This fixes up panics after r273895 .
Reported by: markj
have both kern_open() and kern_openat(); change the callers to use
kern_openat().
This removes one (sometimes two) levels of indirection and
consolidates arguments checks.
Reviewed by: mckusick
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
ever used. It didn't go into stable/10, neither was documented.
It might be useful, but we collectively decided to remove it, rather
leave it abandoned and unmaintained. It is removed in one single
commit, so restoring it should be easy, if anyone wants to reopen
this idea.
Sponsored by: Netflix
It returns only current working directory of given process which saves a lot of
overhead over kern.proc.filedesc if given proc has a lot of open fds.
Submitted by: Tiwei Bie <btw mail.ustc.edu.cn> (slightly modified)
X-Additional: JuniorJobs project
Currently sizeof(struct filedesc0) is 1096 bytes, which means allocations from
malloc use 2048 bytes.
There is no easy way to shrink the structure <= 1024 an it is likely to grow in
the future.
appropriately
Assert FILEDESC_XLOCK_ASSERT only for already used tables in fdgrowtable.
We don't have to call it with the lock held if we are just creating new
filedesc.
As a side note, strictly speaking processes can have fdtables with
fd_lastfile = -1, but then they cannot enter fdgrowtable. Very first file
descriptor they get will be 0 and the only syscall allowing to choose fd number
requires an active file descriptor. Should this ever change, we can add an 'init'
(or similar) parameter to fdgrowtable.
While here add 'fdused_init' which does not perform unnecessary work.
Drop FILEDESC_LOCK_ASSERT from fdisused and rely on callers to hold
it when appropriate. This function is only used with INVARIANTS.
No functional changes intended.
Test for file availability by fde_file != NULL instead of fdisused, this is
consistent with similar checks later.
Drop badfileops check. badfileops don't have DFLAG_PASSABLE set, so it was never
reached in practice.
fdiused is now only used in some KASSERTS, so ifdef it under INVARIANTS.
No functional changes.
without restarting whole lookup
Restart is only needed when fp was closed by current process, which is a much
rarer event than ref/deref by some other thread.
A read barrier was necessary because fd table pointer and table size were
updated separately, opening a window where fget_unlocked could read new size
and old pointer.
This patch puts both these fields into one dedicated structure, pointer to which
is later atomically updated. As such, fget_unlocked only needs data a dependency
barrier which is a noop on all supported architectures.
Reviewed by: kib (previous version)
MFC after: 2 weeks
Rename it to fdsetugidsafety for consistency with other functions.
There is no need to take filedesc lock if not closing any files.
The loop has to verify each file and we are guaranteed fdtable has space
for at least 20 fds. As such there is no need to check fd_lastfile.
While here tidy up is_unsafe.
- Wrong integer type was specified.
- Wrong or missing "access" specifier. The "access" specifier
sometimes included the SYSCTL type, which it should not, except for
procedural SYSCTL nodes.
- Logical OR where binary OR was expected.
- Properly assert the "access" argument passed to all SYSCTL macros,
using the CTASSERT macro. This applies to both static- and dynamically
created SYSCTLs.
- Properly assert the the data type for both static and dynamic
SYSCTLs. In the case of static SYSCTLs we only assert that the data
pointed to by the SYSCTL data pointer has the correct size, hence
there is no easy way to assert types in the C language outside a
C-function.
- Rewrote some code which doesn't pass a constant "access" specifier
when creating dynamic SYSCTL nodes, which is now a requirement.
- Updated "EXAMPLES" section in SYSCTL manual page.
MFC after: 3 days
Sponsored by: Mellanox Technologies
Include sequence counter supports incoditionally [1]. This fixes reprted build
problems with e.g. nvidia driver due to missing opt_capsicum.h.
Replace fishy looking sizeof with offsetof. Make fde_seq the last member in
order to simplify calculations.
Suggested by: kib [1]
X-MFC: with 272505
the upper layers, which interpret it as errno value, which happens to
be ERESTART. The result was spurious restarts of the sysctls in loop,
e.g. kern.proc.proc, instead of returning ENOMEM to caller.
Convert -1 from sbuf_bcat() to ENOMEM, when returning to the callers
expecting errno.
In collaboration with: pho
Sponsored by: The FreeBSD Foundation (kib)
MFC after: 1 week
fp and appropriate capability lookups were not atomic, which could result in
improper capabilities being checked.
This could result either in protection bypass or in a spurious ENOTCAPABLE.
Make fp + capability check atomic with the help of sequence counters.
Reviewed by: kib
MFC after: 3 weeks
struct flock are done in the sys_fcntl(), which mean that compat32 used
direct access to userland pointers.
Move code from sys_fcntl() to new wrapper, kern_fcntl_freebsd(), which
performs neccessary userland memory accesses, and use it from both
native and compat32 fcntl syscalls.
Reported by: jhibbits
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
struct kinfo_file.
- Move the various fill_*_info() methods out of kern_descrip.c and into the
various file type implementations.
- Rework the support for kinfo_ofile to generate a suitable kinfo_file object
for each file and then convert that to a kinfo_ofile structure rather than
keeping a second, different set of code that directly manipulates
type-specific file information.
- Remove the shm_path() and ksem_info() layering violations.
Differential Revision: https://reviews.freebsd.org/D775
Reviewed by: kib, glebius (earlier version)
- Add invfo_rdwr() (for read and write), invfo_ioctl(), invfo_poll(),
and invfo_kqfilter() for use by file types that do not support the
respective operations. Home-grown versions of invfo_poll() were
universally broken (they returned an errno value, invfo_poll()
uses poll_no_poll() to return an appropriate event mask). Home-grown
ioctl routines also tended to return an incorrect errno (invfo_ioctl
returns ENOTTY).
- Use the invfo_*() functions instead of local versions for
unsupported file operations.
- Reorder fileops members to match the order in the structure definition
to make it easier to spot missing members.
- Add several missing methods to linuxfileops used by the OFED shim
layer: fo_write(), fo_truncate(), fo_kqfilter(), and fo_stat(). Most
of these used invfo_*(), but a dummy fo_stat() implementation was
added.
instead of breaking out of the loop and then immediately checking the loop
index so that if it was broken out of the proper value can be returned.
While here, use nitems().
Code trying to take a look has to check fd_refcnt and it is 0 by that time.
This is a follow up to r268505, without this the code would leak memory for
tables bigger than the default.
MFC after: 1 week
Filetable can be shared with other processes. Previous code failed to
clear the pointer for all but the last process getting rid of the table.
This is mostly cosmetics.
Get rid of 'This should happen earlier' comment. Clearing the pointer in
this place is fine as consumers can reliably check for files availability
by inspecting fd_refcnt and vnodes availabity by NULL-checking them.
MFC after: 1 week
o assert in each one that fdp is not shared
o remove unnecessary NULL checks - all userspace processes have fdtables
and kernel processes cannot execve
o remove comments about the danger of fd_ofiles getting reallocated - fdtable
is not shared and fd_ofiles could be only reallocated if new fd was about to be
added, but if that was possible the code would already be buggy as setugidsafety
work could be undone
MFC after: 1 week
We can read refcnt safely and only care if it is equal to 1.
If it could suddenly change from 1 to something bigger the code would be
buggy even in the previous form and transitions from > 1 to 1 are equally racy
and harmless (we copy even though there is no need).
MFC after: 1 week
fd_lastfile is guaranteed to be the biggest open fd, so when the intent
is to iterate over active fds or lookup one, there is no point in looking
beyond that limit.
Few places are left unpatched for now.
MFC after: 1 week
