Fix corruption of coredumps due to procstat notes changing size during
coredump generation. The changes in r287442 required some reworking
since the 'fo_fill_kinfo' file op does not exist in stable/10.
287442:
Detect badly behaved coredump note helpers
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.
287537:
Follow-up to r287442: Move sysctl to compiled-once file
Avoid duplicate sysctl nodes.
288944:
Fix core corruption caused by race in note_procstat_vmmap
This fix is spiritually similar to r287442 and was discovered thanks to
the KASSERT added in that revision.
NT_PROCSTAT_VMMAP output length, when packing kinfo structs, is tied to
the length of filenames corresponding to vnodes in the process' vm map
via vn_fullpath. As vnodes may move during coredump, this is racy.
We do not remove the race, only prevent it from causing coredump
corruption.
- Add a sysctl, kern.coredump_pack_vmmapinfo, to allow users to disable
kinfo packing for PROCSTAT_VMMAP notes. This avoids VMMAP corruption
and truncation, even if names change, at the cost of up to PATH_MAX
bytes per mapped object. The new sysctl is documented in core.5.
- Fix note_procstat_vmmap to self-limit in the second pass. This
addresses corruption, at the cost of sometimes producing a truncated
result.
- Fix PROCSTAT_VMMAP consumers libutil (and libprocstat, via copy-paste)
to grok the new zero padding.
Approved by: re (gjb)
When matching brand to the ELF binary by notes, try to find a brand
with interpreter name exactly matching one wanted by the binary.
Approved by: re (delphij)
Add kern.racct.enable tunable and RACCT_DISABLED config option.
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).
MFC r282901:
Build GENERIC with RACCT/RCTL support by default. Note that it still
needs to be enabled by adding "kern.racct.enable=1" to /boot/loader.conf.
Note those two are MFC-ed together, because the latter one changes the
name of RACCT_DISABLED option to RACCT_DEFAULT_TO_DISABLED. Should have
committed the renaming separately...
Relnotes: yes
Sponsored by: The FreeBSD Foundation
Include OBJT_PHYS VM objects in ELF core dumps. In particular this
includes the shared page allowing debuggers to use the signal trampoline
code to identify signal frames in core dumps.
Allow the kern.osrelease and kern.osreldate sysctl values to be set in a
jail's creation parameters. This allows the kernel version to be reliably
spoofed within the jail whether examined directly with sysctl or
indirectly with the uname -r and -K options.
Export the new osreldate and osrelease jail parms in jail_get(2).
Fix line wrap.
Update kernel inclusions of capability.h to use capsicum.h instead; some
further refinement is required as some device drivers intended to be
portable over FreeBSD versions rely on __FreeBSD_version to decide whether
to include capability.h.
Sponsored by: Google, Inc.
Improve support for XSAVE with debuggers.
- Dump an NT_X86_XSTATE note if XSAVE is in use. This note is designed
to match what Linux does in that 1) it dumps the entire XSAVE area
including the fxsave state, and 2) it stashes a copy of the current
xsave mask in the unused padding between the fxsave state and the
xstate header at the same location used by Linux.
- Teach readelf() to recognize NT_X86_XSTATE notes.
- Change PT_GET/SETXSTATE to take the entire XSAVE state instead of
only the extra portion. This avoids having to always make two
ptrace() calls to get or set the full XSAVE state.
- Add a PT_GET_XSTATE_INFO which returns the length of the current
XSTATE save area (so the size of the buffer needed for PT_GETXSTATE)
and the current XSAVE mask (%xcr0).
an address in the first 2GB of the process's address space. This flag should
have the same semantics as the same flag on Linux.
To facilitate this, add a new parameter to vm_map_find() that specifies an
optional maximum virtual address. While here, fix several callers of
vm_map_find() to use a VMFS_* constant for the findspace argument instead of
TRUE and FALSE.
Reviewed by: alc
Approved by: re (kib)
We cannot busy a page before doing pagefaults.
Infact, it can deadlock against vnode lock, as it tries to vget().
Other functions, right now, have an opposite lock ordering, like
vm_object_sync(), which acquires the vnode lock first and then
sleeps on the busy mechanism.
Before this patch is reinserted we need to break this ordering.
Sponsored by: EMC / Isilon storage division
Reported by: kib
- It does not let pages respect the LRU policy
- It bloats the active/inactive queues of few pages
Try to avoid it as much as possible with the long-term target to
completely remove it.
Use the soft-busy mechanism to protect page content accesses during
short-term operations (like uiomove_fromphys()).
After this change only vm_fault_quick_hold_pages() is still using the
hold mechanism for page content access.
There is an additional complexity there as the quick path cannot
immediately access the page object to busy the page and the slow path
cannot however busy more than one page a time (to avoid deadlocks).
Fixing such primitive can bring to complete removal of the page hold
mechanism.
Sponsored by: EMC / Isilon storage division
Discussed with: alc
Reviewed by: jeff
Tested by: pho
The notes format is a header of sizeof(int), which stores the size of
the corresponding data structure to provide some versioning, and data
in the format as it is returned by a related sysctl call.
The userland tools (procstat(1)) will be taught to extract this data,
providing additional info for postmortem analysis.
PR: kern/173723
Suggested by: jhb
Discussed with: jhb, kib
Reviewed by: jhb (initial version), kib
MFC after: 1 month
function is provided, which is used either to calculate the note size
or output it to sbuf. On the first pass the notes are registered in a
list and the resulting size is found, on the second pass the list is
traversed outputing notes to sbuf. For the sbuf a drain routine is
provided that writes data to a core file.
The main goal of the change is to make coredump to write notes
directly to the core file, without preliminary preparing them all in a
memory buffer. Storing notes in memory is not a problem for the
current, rather small, set of notes we write to the core, but it may
becomes an issue when we start to store procstat notes.
Reviewed by: jhb (initial version), kib
Discussed with: jhb, kib
MFC after: 3 weeks
Although native word padding (i.e. 8-byte on 64bit arch) looks to be
in agreement with standards, other parts of our code and other OSes
use 4-byte alignment.
This is not expected to change alignment for currently generated core
dump notes, as the notes look to consist of structures with sizes
multiple of 8 on 64-bit archs. But there are plans to add additional
notes, where 4-byte vs 8-byte alignment makes difference.
Discussed with: kib
Reviewed by: kib
MFC after: 2 weeks
the first page:
1. Cast uint16_t operands in a multiplication to unsigned int because
otherwise the implicit promotion to int results in a signed
multiplication that can overflow and the behaviour on integer
overflow is undefined.
2. Replace (offset + size > PAGE_SIZE) with (size > PAGE_SIZE - offset)
because the sum may overflow.
- Use the same tests to see if the path to the interpreter is on the first
page. There's no overflow here because size is already limited by
MAXPATHLEN, but the compiler optimises the new tests better. Also fix an
off-by-one error.
- Simplify tests to see if an ELF note program header is on the first page.
This also fixes an off-by-one error.
Reviewed by: kib
MFC after: 1 week
* VM_OBJECT_LOCK and VM_OBJECT_UNLOCK are mapped to write operations
* VM_OBJECT_SLEEP() is introduced as a general purpose primitve to
get a sleep operation using a VM_OBJECT_LOCK() as protection
* The approach must bear with vm_pager.h namespace pollution so many
files require including directly rwlock.h
In particular, do not lock Giant conditionally when calling into the
filesystem module, remove the VFS_LOCK_GIANT() and related
macros. Stop handling buffers belonging to non-mpsafe filesystems.
The VFS_VERSION is bumped to indicate the interface change which does
not result in the interface signatures changes.
Conducted and reviewed by: attilio
Tested by: pho
If you have a binary on a filesystem which is also mounted over by
nullfs, you could execute the binary from the lower filesystem, or
from the nullfs mount. When executed from lower filesystem, the lower
vnode gets VV_TEXT flag set, and the file cannot be modified while the
binary is active. But, if executed as the nullfs alias, only the
nullfs vnode gets VV_TEXT set, and you still can open the lower vnode
for write.
Add a set of VOPs for the VV_TEXT query, set and clear operations,
which are correctly bypassed to lower vnode.
Tested by: pho (previous version)
MFC after: 2 weeks
ELF parser. Specifically, do not allow note reader and interpreter
path comparision in the brandelf code to read past end of the page.
This may happen if specially crafter ELF image is activated.
Submitted by: Lukasz Wojcik <lukasz.wojcik zoho com>
MFC after: 3 days
usermode, using shared page. The structures and functions have vdso
prefix, to indicate the intended location of the code in some future.
The versioned per-algorithm data is exported in the format of struct
vdso_timehands, which mostly repeats the content of in-kernel struct
timehands. Usermode reading of the structure can be lockless.
Compatibility export for 32bit processes on 64bit host is also
provided. Kernel also provides usermode with indication about
currently used timecounter, so that libc can fall back to syscall if
configured timecounter is unknown to usermode code.
The shared data updates are initiated both from the tc_windup(), where
a fast task is queued to do the update, and from sysctl handlers which
change timecounter. A manual override switch
kern.timecounter.fast_gettime allows to turn off the mechanism.
Only x86 architectures export the real algorithm data, and there, only
for tsc timecounter. HPET counters page could be exported as well, but
I prefer to not further glue the kernel and libc ABI there until
proper vdso-based solution is developed.
Minimal stubs neccessary for non-x86 architectures to still compile
are provided.
Discussed with: bde
Reviewed by: jhb
Tested by: flo
MFC after: 1 month
to an OBJT_VNODE-specific field of the vm object. The same
information can be just as easily obtained from the struct vattr that
is in struct image_params if the latter is passed to
elf*_load_section(). Moreover, by replacing the vmspace and vm
object parameters to elf*_load_section() with a struct image_params
parameter, we actually reduce the size of the object code.
In collaboration with: kib
won't happen before 9.0. This commit adds "#ifdef RACCT" around all the
"PROC_LOCK(p); racct_whatever(p, ...); PROC_UNLOCK(p)" instances, in order
to avoid useless locking/unlocking in kernels built without "options RACCT".
more explicit comments about what's going on and what future maintainers
need to do when e.g. adding a new operation to a sys_machdep.c.
Approved by: mentor(rwatson), re(bz)
should_yield(). Use this in various places. Encapsulate the common
case of check-and-yield into a new function maybe_yield().
Change several checks for a magic number of iterations to use
should_yield() instead.
MFC after: 1 week
PT_GNU_STACK program header, if present and enabled. Two new sysctls
are provided, kern.elf32.nxstack and kern.elf64.nxstack, that allow to
enable PT_GNU_STACK for ABIs of specified bitsize, if ABI decided to
support shared page.
Inform rtld about access mode of the stack initial mapping by
AT_STACKPROT aux vector.
At the moment, the default is disabled, waiting for the usermode
support bits.
thread specific informations.
In order to do that, and in order to avoid KBI breakage with existing
infrastructure the following semantic is implemented:
- For live programs, a new member to the PT_LWPINFO is added (pl_tdname)
- For cores, a new ELF note is added (NT_THRMISC) that can be used for
storing thread specific, miscellaneous, informations. Right now it is
just popluated with a thread name.
GDB, then, retrieves the correct informations from the corefile via the
BFD interface, as it groks the ELF notes and create appropriate
pseudo-sections.
Sponsored by: Sandvine Incorporated
Tested by: gianni
Discussed with: dim, kan, kib
MFC after: 2 weeks
In particular, provide pagesize and pagesizes array, the canary value
for SSP use, number of host CPUs and osreldate.
Tested by: marius (sparc64)
MFC after: 1 month
