- struct plimit includes a mutex to protect a reference count. The plimit
structure is treated similarly to struct ucred in that is is always copy
on write, so having a reference to a structure is sufficient to read from
it without needing a further lock.
- The proc lock protects the p_limit pointer and must be held while reading
limits from a process to keep the limit structure from changing out from
under you while reading from it.
- Various global limits that are ints are not protected by a lock since
int writes are atomic on all the archs we support and thus a lock
wouldn't buy us anything.
- All accesses to individual resource limits from a process are abstracted
behind a simple lim_rlimit(), lim_max(), and lim_cur() API that return
either an rlimit, or the current or max individual limit of the specified
resource from a process.
- dosetrlimit() was renamed to kern_setrlimit() to match existing style of
other similar syscall helper functions.
- The alpha OSF/1 compat layer no longer calls getrlimit() and setrlimit()
(it didn't used the stackgap when it should have) but uses lim_rlimit()
and kern_setrlimit() instead.
- The svr4 compat no longer uses the stackgap for resource limits calls,
but uses lim_rlimit() and kern_setrlimit() instead.
- The ibcs2 compat no longer uses the stackgap for resource limits. It
also no longer uses the stackgap for accessing sysctl's for the
ibcs2_sysconf() syscall but uses kernel_sysctl() instead. As a result,
ibcs2_sysconf() no longer needs Giant.
- The p_rlimit macro no longer exists.
Submitted by: mtm (mostly, I only did a few cleanups and catchups)
Tested on: i386
Compiled on: alpha, amd64
systems where the data/stack/etc limits are too big for a 32 bit process.
Move the 5 or so identical instances of ELF_RTLD_ADDR() into imgact_elf.c.
Supply an ia32_fixlimits function. Export the clip/default values to
sysctl under the compat.ia32 heirarchy.
Have mmap(0, ...) respect the current p->p_limits[RLIMIT_DATA].rlim_max
value rather than the sysctl tweakable variable. This allows mmap to
place mappings at sensible locations when limits have been reduced.
Have the imgact_elf.c ld-elf.so.1 placement algorithm use the same
method as mmap(0, ...) now does.
Note that we cannot remove all references to the sysctl tweakable
maxdsiz etc variables because /etc/login.conf specifies a datasize
of 'unlimited'. And that causes exec etc to fail since it can no
longer find space to mmap things.
the stack to be changed in a way incompatible with elf32_map_insert()
where we used data_buf without initializing it for when the partial
mapping resulting in a misaligned image (typical when the page size
implied by the image is not the same as the page size in use by the
kernel). Since data_buf is passed by reference to vm_map_find(), the
compiler cannot warn about it.
While here, move all local variables to the top of the function.
included in the kernel. Include imgact_elf.c in conf/files, instead of
both imgact_elf32.c and imgact_elf64.c, which will use the default word
size for an architecture as defined in machine/elf.h. Architectures that
wish to build an additional image activator for an alternate word size can
include either imgact_elf32.c or imgact_elf64.c in files.${ARCH}, which
allows it to be dependent on MD options instead of solely on architecture.
Glanced at by: peter
The duplication is caused by the fact that imgact_elf.c is included
by both imgact_elf32.c and imgact_elf64.c and both are compiled by
default on ia64. Consequently, we have two seperate copies of the
elf_legacy_coredump variable due to them being declared static, and
two entries for the same sysctl in the linker set, both referencing
the unique copy of the elf_legacy_coredump variable. Since the second
sysctl cannot be registered, one of the elf_legacy_coredump variables
can not be tuned (if ordering still holds, it's the ELF64 related one).
The only solution is to create two different sysctl variables, just
like the elf<32|64>_trace sysctl variables. This unfortunately is an
(user) interface change, but unavoidable. Thus, on ELF32 platforms
the sysctl variable is called elf32_legacy_coredump and on ELF64
platforms it is called elf64_legacy_coredump. Platforms that have
both ELF formats have both sysctl variables.
These variables should probably be retired sooner rather than later.
skipping read-only pages, which can result in valuable non-text-related
data not getting dumped, the ELF loader and the dynamic loader now mark
read-only text pages NOCORE and the coredump code only checks (primarily) for
complete inaccessibility of the page or NOCORE being set.
Certain applications which map large amounts of read-only data will
produce much larger cores. A new sysctl has been added,
debug.elf_legacy_coredump, which will revert to the old behavior.
This commit represents collaborative work by all parties involved.
The PR contains a program demonstrating the problem.
PR: kern/45994
Submitted by: "Peter Edwards" <pmedwards@eircom.net>, Archie Cobbs <archie@dellroad.org>
Reviewed by: jdp, dillon
MFC after: 7 days
in the ELF code. Missed in earlier merge from the MAC tree.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
describes an image activation instance. Instead, make use of the
existing fname structure entry, and introduce two new entries,
userspace_argv, and userspace_envv. With the addition of
mac_execve(), this divorces the image structure from the specifics
of the execve() system call, removes a redundant pointer, etc.
No semantic change from current behavior, but it means that the
structure doesn't depend on syscalls.master-generated includes.
There seems to be some redundant initialization of imgact entries,
which I have maintained, but which could probably use some cleaning
up at some point.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
ones with one text and one data section.
The text and data rlimit checks still needs to be fixed to properly
accout for additional sections.
Reviewed by: peter (slightly different patch version)
constants VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS, USRSTACK and PS_STRINGS.
This is mainly so that they can be variable even for the native abi, based
on different machine types. Get stack protections from the sysentvec too.
This makes it trivial to map the stack non-executable for certain abis, on
machines that support it.
out that there is no easy way to discern the difference between a text
segment and a data segment through the read-only OR execute attribute
in the elf segment header, so revert the algorithm to what it was before.
Neither can we account for multiple data load segments in the vmspace
structure (at least not without more work), due to assumptions obreak()
makes in regards to the data start and data size fields.
Retain RLIMIT_VMEM checking by using a local variable to track the
total bytes of data being loaded.
Reviewed by: peter
X-MFC after: ASAP
so that it works on the Alpha. This defines the segment that the entry
point exists in as 'text' and any others (usually one) as data.
Submitted by: tmm
Tested on: i386, alpha
brand early in the process of loading an elf file, so that we can
identify the sysentvec, and so that we do not continue if we do not
have a brand (and thus a sysentvec). Use the values in the sysentvec
for the page size and vm ranges unconditionally, since they are all
filled in now.
compat code. Clean up accounting for multiple segments. Part 1/2.
Submitted by: Andrey Alekseyev <uitm@zenon.net> (with some modifications)
MFC after: 3 days
make a series of modifications to the credential arguments relating
to file read and write operations to cliarfy which credential is
used for what:
- Change fo_read() and fo_write() to accept "active_cred" instead of
"cred", and change the semantics of consumers of fo_read() and
fo_write() to pass the active credential of the thread requesting
an operation rather than the cached file cred. The cached file
cred is still available in fo_read() and fo_write() consumers
via fp->f_cred. These changes largely in sys_generic.c.
For each implementation of fo_read() and fo_write(), update cred
usage to reflect this change and maintain current semantics:
- badfo_readwrite() unchanged
- kqueue_read/write() unchanged
pipe_read/write() now authorize MAC using active_cred rather
than td->td_ucred
- soo_read/write() unchanged
- vn_read/write() now authorize MAC using active_cred but
VOP_READ/WRITE() with fp->f_cred
Modify vn_rdwr() to accept two credential arguments instead of a
single credential: active_cred and file_cred. Use active_cred
for MAC authorization, and select a credential for use in
VOP_READ/WRITE() based on whether file_cred is NULL or not. If
file_cred is provided, authorize the VOP using that cred,
otherwise the active credential, matching current semantics.
Modify current vn_rdwr() consumers to pass a file_cred if used
in the context of a struct file, and to always pass active_cred.
When vn_rdwr() is used without a file_cred, pass NOCRED.
These changes should maintain current semantics for read/write,
but avoid a redundant passing of fp->f_cred, as well as making
it more clear what the origin of each credential is in file
descriptor read/write operations.
Follow-up commits will make similar changes to other file descriptor
operations, and modify the MAC framework to pass both credentials
to MAC policy modules so they can implement either semantic for
revocation.
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
- v_vflag is protected by the vnode lock and is used when synchronization
with VOP calls is needed.
- v_iflag is protected by interlock and is used for dealing with vnode
management issues. These flags include X/O LOCK, FREE, DOOMED, etc.
- All accesses to v_iflag and v_vflag have either been locked or marked with
mp_fixme's.
- Many ASSERT_VOP_LOCKED calls have been added where the locking was not
clear.
- Many functions in vfs_subr.c were restructured to provide for stronger
locking.
Idea stolen from: BSD/OS
handler in the kernel at the same time. Also, allow for the
exec_new_vmspace() code to build a different sized vmspace depending on
the executable environment. This is a big help for execing i386 binaries
on ia64. The ELF exec code grows the ability to map partial pages when
there is a page size difference, eg: emulating 4K pages on 8K or 16K
hardware pages.
Flesh out the i386 emulation support for ia64. At this point, the only
binary that I know of that fails is cvsup, because the cvsup runtime
tries to execute code in pages not marked executable.
Obtained from: dfr (mostly, many tweaks from me).
- Grab the vnode object early in exec when we still have the vnode lock.
- Cache the object in the image_params.
- Make use of the cached object in imgact_*.c
in vn_rdwr_inchunks(), allowing other processes to gain an exclusive
lock on the vnode. Specifically: directory scanning, to avoid a race to the
root directory, and multiple child processes coring simultaniously so they
can figure out that some other core'ing child has an exclusive adv lock and
just exit instead.
This completely fixes performance problems when large programs core. You
can have hundreds of copies (forked children) of the same binary core all
at once and not notice.
MFC after: 3 days
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
me (addition of vn_rdwr_inchunks). The problem Yahoo is solving is that
if you have large process images core dumping, or you have a large number of
forked processes all core dumping at the same time, the original coredump code
would leave the vnode locked throughout. This can cause the directory vnode
to get locked up, which can cause the parent directory vnode to get locked
up, and so on all the way to the root node, locking the entire machine up
for extremely long periods of time.
This patch solves the problem in two ways. First it uses an advisory
non-blocking lock to abort multiple processes trying to core to the same
file. Second (my contribution) it chunks up the writes and uses bwillwrite()
to avoid holding the vnode locked while blocking in the buffer cache.
Submitted by: ps
Reviewed by: dillon
MFC after: 2 weeks
(this commit is just the first stage). Also add various GIANT_ macros to
formalize the removal of Giant, making it easy to test in a more piecemeal
fashion. These macros will allow us to test fine-grained locks to a degree
before removing Giant, and also after, and to remove Giant in a piecemeal
fashion via sysctl's on those subsystems which the authors believe can
operate without Giant.
vm_mtx does not recurse and is required for most low level
vm operations.
faults can not be taken without holding Giant.
Memory subsystems can now call the base page allocators safely.
Almost all atomic ops were removed as they are covered under the
vm mutex.
Alpha and ia64 now need to catch up to i386's trap handlers.
FFS and NFS have been tested, other filesystems will need minor
changes (grabbing the vm lock when twiddling page properties).
Reviewed (partially) by: jake, jhb
