read.2: Describe debug.iosize_max_clamp

PR: 276937

(cherry picked from commit 3e9515846f8cbff0ecccaab65d9f70890d04429e)

Remove $FreeBSD$: one-line nroff pattern

Remove /^\.\\"\s*\$FreeBSD\$$\n/

Revert "Add extra EINVAL information about wrong block size to read(2)/write(2)"

This reverts commit 1c2be25f6080ee63baeae55e45761e1310d1b756.

kib@ pointed out that it is perfectly fine to write at

Revert "Add extra EINVAL information about wrong block size to read(2)/write(2)"

This reverts commit 1c2be25f6080ee63baeae55e45761e1310d1b756.

kib@ pointed out that it is perfectly fine to write at arbitrary regular
file offsets. For example, in a 4K block size character device, geom
doesn't support writing / reading 515 byte blocks. The description is
perhaps not applicable to all EINVALs returned.

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Add extra EINVAL information about wrong block size to read(2)/write(2)

The read system call will return EINVAL if the current file offset is
not a multiple of the block size. This also applies to w

Add extra EINVAL information about wrong block size to read(2)/write(2)

The read system call will return EINVAL if the current file offset is
not a multiple of the block size. This also applies to write(2). Add an
entry for EINVAL about this error to both man pages.

PR: 91149
Event: Aberdeen Hackathon 2022
Differential Revision: https://reviews.freebsd.org/D24617

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vfs: add restrictions to read(2) of a directory [2/2]

This commit adds the priv(9) that waters down the sysctl to make it only
allow read(2) of a dirfd by the system root. Jailed root is not allowed

vfs: add restrictions to read(2) of a directory [2/2]

This commit adds the priv(9) that waters down the sysctl to make it only
allow read(2) of a dirfd by the system root. Jailed root is not allowed, but
jail policy and superuser policy will abstain from allowing/denying it so
that a MAC module can fully control the policy.

Such a MAC module has been written, and can be found at:
https://people.freebsd.org/~kevans/mac_read_dir-0.1.0.tar.gz

It is expected that the MAC module won't be needed by many, as most only
need to do such diagnostics that require this behavior as system root
anyways. Interested parties are welcome to grab the MAC module above and
create a port or locally integrate it, and with enough support it could see
introduction to base. As noted in mac_read_dir.c, it is released under the
BSD 2 clause license and allows the restrictions to be lifted for only
jailed root or for all unprivileged users.

PR: 246412
Reviewed by: mckusick, kib, emaste, jilles, cy, phk, imp (all previous)
Reviewed by: rgrimes (latest version)
Differential Revision: https://reviews.freebsd.org/D24596

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vfs: add restrictions to read(2) of a directory [1/2]

Historically, we've allowed read() of a directory and some filesystems will
accommodate (e.g. ufs/ffs, msdosfs). From the history department sta

vfs: add restrictions to read(2) of a directory [1/2]

Historically, we've allowed read() of a directory and some filesystems will
accommodate (e.g. ufs/ffs, msdosfs). From the history department staffed by
Warner: <<EOF

pdp-7 unix seemed to allow reading directories, but they were weird, special
things there so I'm unsure (my pdp-7 assembler sucks).

1st Edition's sources are lost, mostly. The kernel allows it. The
reconstructed sources from 2nd or 3rd edition read it though.

V6 to V7 changed the filesystem format, and should have been a warning, but
reading directories weren't materially changed.

4.1b BSD introduced readdir because of UFS. UFS broke all directory reading
programs in 1983. ls, du, find, etc all had to be rewritten. readdir() and
friends were introduced here.

SysVr3 picked up readdir() in 1987 for the AT&T fork of Unix. SysVr4 updated
all the directory reading programs in 1988 because different filesystem
types were introduced.

In the 90s, these interfaces became completely ubiquitous as PDP-11s running
V7 faded from view and all the folks that initially started on V7 upgraded
to SysV. Linux never supported this (though I've not done the software
archeology to check) because it has always had a pathological diversity of
filesystems.
EOF

Disallowing read(2) on a directory has the side-effect of masking
application bugs from relying on other implementation's behavior
(e.g. Linux) of rejecting these with EISDIR across the board, but allowing
it has been a vector for at least one stack disclosure bug in the past[0].

By POSIX, this is implementation-defined whether read() handles directories
or not. Popular implementations have chosen to reject them, and this seems
sensible: the data you're reading from a directory is not structured in some
unified way across filesystem implementations like with readdir(2), so it is
impossible for applications to portably rely on this.

With this patch, we will reject most read(2) of a dirfd with EISDIR. Users
that know what they're doing can conscientiously set
bsd.security.allow_read_dir=1 to allow read(2) of directories, as it has
proven useful for debugging or recovery. A future commit will further limit
the sysctl to allow only the system root to read(2) directories, to make it
at least relatively safe to leave on for longer periods of time.

While we're adding logic pertaining to directory vnodes to vn_io_fault, an
additional assertion has also been added to ensure that we're not reaching
vn_io_fault with any write request on a directory vnode. Such request would
be a logical error in the kernel, and must be debugged rather than allowing
it to potentially silently error out.

Commented out shell aliases have been placed in root's chsrc/shrc to promote
awareness that grep may become noisy after this change, depending on your
usage.

A tentative MFC plan has been put together to try and make it as trivial as
possible to identify issues and collect reports; note that this will be
strongly re-evaluated. Tentatively, I will MFC this knob with the default as
it is in HEAD to improve our odds of actually getting reports. The future
priv(9) to further restrict the sysctl WILL NOT BE MERGED BACK, so the knob
will be a faithful reversion on stable/12. We will go into the merge
acknowledging that the sysctl default may be flipped back to restore
historical behavior at *any* point if it's warranted.

[0] https://www.freebsd.org/security/advisories/FreeBSD-SA-19:10.ufs.asc

PR: 246412
Reviewed by: mckusick, kib, emaste, jilles, cy, phk, imp (all previous)
Reviewed by: rgrimes (latest version)
MFC after: 1 month (note the MFC plan mentioned above)
Relnotes: absolutely, but will amend previous RELNOTES entry
Differential Revision: https://reviews.freebsd.org/D24596

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Document EINTEGRITY errors for many system calls.

EINTEGRITY was previously documented as a UFS-specific error for
mount(2). This documents EINTEGRITY as a filesystem-independent error
that may be

Document EINTEGRITY errors for many system calls.

EINTEGRITY was previously documented as a UFS-specific error for
mount(2). This documents EINTEGRITY as a filesystem-independent error
that may be reported by the backing store of a filesystem.

While here, document EIO as a filesystem-independent error for both
mount(2) and posix_fadvise(2). EIO was previously only documented for
UFS for mount(2).

Reviewed by: mckusick
Suggested by: mckusick
MFC after: 2 weeks
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D24168

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Document atomicity for read(2) and write(2).

Take part of the text from POSIX 2018 edition and describe the
atomicity requirements for read and write syscalls. See p1003.1-2018,
Vol.2, 2.9.7 Thread

Document atomicity for read(2) and write(2).

Take part of the text from POSIX 2018 edition and describe the
atomicity requirements for read and write syscalls. See p1003.1-2018,
Vol.2, 2.9.7 Threads interaction with Regular File Operations.

Reviewed by: asomers
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Differential revision: https://reviews.freebsd.org/D20867

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Mark all the system calls that were in 1st Edition Unix as such in the
HISTORY section. Note: Any system calls that were added prior to v7,
but after v1 weren't changed.

Obtained from: http://www.tu

Mark all the system calls that were in 1st Edition Unix as such in the
HISTORY section. Note: Any system calls that were added prior to v7,
but after v1 weren't changed.

Obtained from: http://www.tuhs.org/cgi-bin/utree.pl?file=V1/man/man2

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Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <[email protected]>
Pull Request: https://github.com/freebsd/freebsd/pull/96

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Remove sys/types.h due to STANDARDS and unistd.h also includes sys/types.h.

Consistently reference file descriptors as "fd". 55 other manpages
used "fd", while these used "d" and "filedes".

MFC after: 1 week
Approved by: gjb
Approved by: re (delphij)

pread(2) might fail with EBUSY, so document it

PR: docs/167201
Submitted by: Kurt Jaeger <[email protected]>
Approved by: cperciva
MFC after: 3 days

The sys/uio.h header is needed only for readv(2), preadv(2), writev(2) and
pwritev(2). Document it more precisely.

Reviewed by: jilles
MFC after: 3 days

Per Regents of the University of Calfornia letter, remove advertising
clause.

# If I've done so improperly on a file, please let me know.

Avoid a potential hard sentence break.

o Follow the trend and try to explain what the slow device is.
Not ideal but better than nothing.

Obtained from: OpenBSD, NetBSD

-mdoc sweep.

Document the ECONNRESET errno value.

- Add two new system calls: preadv() and pwritev() which are like readv()
and writev() except that they take an additional offset argument and do
not change the current file position. In SAT spe

- Add two new system calls: preadv() and pwritev() which are like readv()
and writev() except that they take an additional offset argument and do
not change the current file position. In SAT speak:
preadv:readv::pread:read and pwritev:writev::pwrite:write.
- Try to reduce code duplication some by merging most of the old
kern_foov() and dofilefoo() functions into new dofilefoo() functions
that are called by kern_foov() and kern_pfoov(). The non-v functions
now all generate a simple uio on the stack from the passed in arguments
and then call kern_foov(). For example, read() now just builds a uio and
calls kern_readv() and pwrite() just builds a uio and calls kern_pwritev().

PR: kern/80362
Submitted by: Marc Olzheim marcolz at stack dot nl (1)
Approved by: re (scottl)
MFC after: 1 week

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read(), pread(), write(), and pwrite() return EINVAL if they are asked
for more than INT_MAX bytes.

Nitpicking on grammar.

Reword the last change a bit, add mdoc(7) markup.

Discussed with: bde

Explain it is a negative offset that EINVAL may indicate.
Now readers won't get an impression that pointing to beyond
the current end of file will result in EINVAL.

MFC after: 1 week

Mechanically kill hard sentence breaks.