as suggested by Matt's comment. Also fix some style and paranoia issues.
The entire function could benefit from review by a VFS guru.
MFC after: 6 weeks
Since we used an sbuf of size resid to accumulate dirents, we would end
up returning one byte short when we had enough dirents to fill or exceed
the size of the sbuf (the last byte being lost to bogus NUL termination)
causing the next call to return EINVAL due to an unaligned offset. This
went undetected for a long time because I did most of my testing in
single-user mode, where there are rarely enough processes to fill the
4096-byte buffer ls(1) uses. The most common symptom of this bug is that
tab completion of /proc or /compat/linux/proc does not work properly when
many processes are running.
Also, a check near the top would return EINVAL if resid was smaller than
PFS_DELEN, even if it was 0, which is frequently the case and perfectly
allowable. Change the test so that it returns 0 if resid is 0.
MFC after: 2 weeks
initializations but we did have lofty goals and big ideals.
Adjust to more contemporary circumstances and gain type checking.
Replace the entire vop_t frobbing thing with properly typed
structures. The only casualty is that we can not add a new
VOP_ method with a loadable module. History has not given
us reason to belive this would ever be feasible in the the
first place.
Eliminate in toto VOCALL(), vop_t, VNODEOP_SET() etc.
Give coda correct prototypes and function definitions for
all vop_()s.
Generate a bit more data from the vnode_if.src file: a
struct vop_vector and protype typedefs for all vop methods.
Add a new vop_bypass() and make vop_default be a pointer
to another struct vop_vector.
Remove a lot of vfs_init since vop_vector is ready to use
from the compiler.
Cast various vop_mumble() to void * with uppercase name,
for instance VOP_PANIC, VOP_NULL etc.
Implement VCALL() by making vdesc_offset the offsetof() the
relevant function pointer in vop_vector. This is disgusting
but since the code is generated by a script comparatively
safe. The alternative for nullfs etc. would be much worse.
Fix up all vnode method vectors to remove casts so they
become typesafe. (The bulk of this is generated by scripts)
returning incompletely initialized processes. This problem was
eliminated by kern_proc.c:1.215, which causes pfind() not to
return processes in the PRS_NEW state.
check whether p_ucred is NULL or not in pfs_getattr() before
dereferencing the credential, and return ENOENT if there wasn't one.
This is a symptom of a larger problem, wherein pfind() can return
references to incompletely initialized processes, and we instead ought
to not return them, or check the process state before acting on the
process.
Reported by: kris
Discussed with: tjr, others
one go before returning. This avoids calling uiomove() while holding
allproc_lock.
Don't adjust uio->uio_offset manually, uiomove() does that for us.
Don't drop allproc_lock before calling panic().
Suggested by: alfred
validating the offset within a given memory buffer before handing the
real work off to uiomove(9).
Use uiomove_frombuf in procfs to correct several issues with
integer arithmetic that could result in underflows/overflows. As a
side-effect, the code is significantly simplified.
Add additional sanity checks when computing a memory allocation size
in pfs_read.
Submitted by: rwatson (original uiomove_frombuf -- bugs are mine :-)
Reported by: Joost Pol <joost@pine.nl> (integer underflows/overflows)
also fixes pfs_access() since it relies on VOP_GETATTR() which will call
pfs_getattr(). This prevents jailed processes from discovering the
existence, start time and ownership of processes outside the jail.
PR: kern/48156
directories. Previously, pfs_iterate() would return -1 when it
reached the end of the process list while processing a process
directory node, even if the parent directory contained further nodes
(which is the case for the linprocfs root directory, where the process
directory node is actually first in the list). With this patch,
pfs_iterate() will continue to traverse the parent directory's node
list after exhausting the process list (as was the intention all
along). The code should hopefully be easier to read as well.
While I'm here, have pfs_iterate() assert that the allproc lock is
held.
kern/vfs_defaults.c it is wrong for the individual filesystems to use
the std* functions as that prevents override of the default.
Found by: src/tools/tools/vop_table
"refreshing" the label on the vnode before use, just get the label
right from inception. For single-label file systems, set the label
in the generic VFS getnewvnode() code; for multi-label file systems,
leave the labeling up to the file system. With UFS1/2, this means
reading the extended attribute during vfs_vget() as the inode is
pulled off disk, rather than hitting the extended attributes
frequently during operations later, improving performance. This
also corrects sematics for shared vnode locks, which were not
previously present in the system. This chances the cache
coherrency properties WRT out-of-band access to label data, but in
an acceptable form. With UFS1, there is a small race condition
during automatic extended attribute start -- this is not present
with UFS2, and occurs because EAs aren't available at vnode
inception. We'll introduce a work around for this shortly.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
unlocked accesses to v_usecount.
- Lock access to the buf lists in the various sync routines. interlock
locking could be avoided almost entirely in leaf filesystems if the
fsync function had a generic helper.
kernel access control.
Modify pseudofs so that it can support synthetic file systems with
the multilabel flag set. In particular, implement vop_refreshlabel()
as pn_refreshlabel(). Implement pfs_refreshlabel() to invoke this,
and have it fall back to the mount label if the file system does
not implement pn_refreshlabel() for the node. Otherwise, permit
the file system to determine how the service is provided.
Approved by: des
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
- Initialize lock structure in vncache_alloc
- Return locked vnodes from vncache_alloc
- Setup vnode op vectors to use default lock, unlock, and islocked
- Implement simple locking scheme required for lookup
pointer instead of a proc pointer and require the process pointed to
by the second argument to be locked. We now use the thread ucred reference
for the credential checks in p_can*() as a result. p_canfoo() should now
no longer need Giant.
o Modify the system call syntax for extattr_{get,set}_{fd,file}() so
as not to use the scatter gather API (which appeared not to be used
by any consumers, and be less portable), rather, accepts 'data'
and 'nbytes' in the style of other simple read/write interfaces.
This changes the API and ABI.
o Modify system call semantics so that extattr_get_{fd,file}() return
a size_t. When performing a read, the number of bytes read will
be returned, unless the data pointer is NULL, in which case the
number of bytes of data are returned. This changes the API only.
o Modify the VOP_GETEXTATTR() vnode operation to accept a *size_t
argument so as to return the size, if desirable. If set to NULL,
the size will not be returned.
o Update various filesystems (pseodofs, ufs) to DTRT.
These changes should make extended attributes more useful and more
portable. More commits to rebuild the system call files, as well
as update userland utilities to follow.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
the wrong VOP descriptor. This misuse caused VFS-cached vnodes to be
re-cached, resulting in the leak. This commit is an interim fix until DES
has a chance to rework the code involved.
- Add a third callback to the pfs_node structure. This one simply returns
non-zero if the specified requesting process is allowed to access the
specified node for the specified target process. This is used in
addition to the usual permission checks, e.g. when certain files don't
make sense for certain (system) processes.
- Make sure that pfs_lookup() and pfs_readdir() don't yap about files
which aren't pfs_visible(). Also check pfs_visible() before performing
reads and writes, to prevent the kind of races reported in SA-00:77 and
SA-01:55 (fork a child, open /proc/child/ctl, have that child fork a
setuid binary, and assume control of it).
- Add some more trace points.
- Rearrange the flag constants a little to simplify specifying and testing
for readability and writeability.
pseudofs_vnops.c:
- Track the aforementioned change.
- Add checks to pfs_open() to prevent opening read-only files for writing
or vice versa (pfs_{read,write} would block the actual reads and writes,
but it's still a bug to allow the open() to succeed). Also, return
EOPNOTSUPP if the caller attempts to lock the file.
- Add more trace points.
- Remove hardcoded uid, gid, mode from struct pfs_node; make pfs_getattr()
smart enough to get it right most of the time, and allow for callbacks
to handle the remaining cases. Rework the definition macros to match.
- Add lots of (conditional) debugging output.
- Fix a long-standing bug inherited from procfs: don't pretend to be a
read-only file system. Instead, return EOPNOTSUPP for operations we
truly can't support and allow others to fail silently. In particular,
pfs_lookup() now treats CREATE as LOOKUP. This may need more work.
- In pfs_lookup(), if the parent node is process-dependent, check that
the process in question still exists.
- Implement pfs_open() - its only current function is to check that the
process opening the file can see the process it belongs to.
- Finish adding support for writeable nodes.
- Bump module version number.
- Introduce lots of new bugs.
Note ALL MODULES MUST BE RECOMPILED
make the kernel aware that there are smaller units of scheduling than the
process. (but only allow one thread per process at this time).
This is functionally equivalent to teh previousl -current except
that there is a thread associated with each process.
Sorry john! (your next MFC will be a doosie!)
Reviewed by: peter@freebsd.org, dillon@freebsd.org
X-MFC after: ha ha ha ha
