execute a ET_DYN binary (shared object).
This does not make much sense, but some linux scripts expect to be able to
execute /lib/ld-linux.so.2 (ldd comes to mind).
The sysctl defaults to 0.
MFC after: 3 days
osf1_signal.c:1.41, amd64/amd64/trap.c:1.291, linux_socket.c:1.60,
svr4_fcntl.c:1.36, svr4_ioctl.c:1.23, svr4_ipc.c:1.18, svr4_misc.c:1.81,
svr4_signal.c:1.34, svr4_stat.c:1.21, svr4_stream.c:1.55,
svr4_termios.c:1.13, svr4_ttold.c:1.15, svr4_util.h:1.10,
ext2_alloc.c:1.43, i386/i386/trap.c:1.279, vm86.c:1.58,
unaligned.c:1.12, imgact_elf.c:1.164, ffs_alloc.c:1.133:
Now that Giant is acquired in uprintf() and tprintf(), the caller no
longer leads to acquire Giant unless it also holds another mutex that
would generate a lock order reversal when calling into these functions.
Specifically not backed out is the acquisition of Giant in nfs_socket.c
and rpcclnt.c, where local mutexes are held and would otherwise violate
the lock order with Giant.
This aligns this code more with the eventual locking of ttys.
Suggested by: bde
as they both interact with the tty code (!MPSAFE) and may sleep if the
tty buffer is full (per comment).
Modify all consumers of uprintf() and tprintf() to hold Giant around
calls into these functions. In most cases, this means adding an
acquisition of Giant immediately around the function. In some cases
(nfs_timer()), it means acquiring Giant higher up in the callout.
With these changes, UFS no longer panics on SMP when either blocks are
exhausted or inodes are exhausted under load due to races in the tty
code when running without Giant.
NB: Some reduction in calls to uprintf() in the svr4 code is probably
desirable.
NB: In the case of nfs_timer(), calling uprintf() while holding a mutex,
or even in a callout at all, is a bad idea, and will generate warnings
and potential upset. This needs to be fixed, but was a problem before
this change.
NB: uprintf()/tprintf() sleeping is generally a bad ideas, as is having
non-MPSAFE tty code.
MFC after: 1 week
links and the execution of ELF binaries. Two problems were found:
1) The link path wasn't tagged as being MP safe and thus was not properly
protected.
2) The ELF interpreter vnode wasnt being locked in namei(9) and thus was
insufficiently protected.
This commit makes the following changes:
-Sets the MPSAFE flag in NDINIT for symbolic link paths
-Sets the MPSAFE flag in NDINIT and introduce a vfslocked variable which
will be used to instruct VFS_UNLOCK_GIANT to unlock Giant if it has been
picked up.
-Drop in an assertion into vfs_lookup which ensures that if the MPSAFE
flag is NOT set, that we have picked up giant. If not panic (if WITNESS
compiled into the kernel). This should help us find conditions where vnode
operations are in-sufficiently protected.
This is a RELENG_6 candidate.
Discussed with: jeff
MFC after: 4 days
This is good enough to be able to run a RELENG_4 gdb binary against
a RELENG_4 application, along with various other tools (eg: 4.x gcore).
We use this at work.
ia32_reg.[ch]: handle the 32 bit register file format, used by ptrace,
procfs and core dumps.
procfs_*regs.c: vary the format of proc/XXX/*regs depending on the client
and target application.
procfs_map.c: Don't print a 64 bit value to 32 bit consumers, or their
sscanf fails. They expect an unsigned long.
imgact_elf.c: produce a valid 32 bit coredump for 32 bit apps.
sys_process.c: handle 32 bit consumers debugging 32 bit targets. Note
that 64 bit consumers can still debug 32 bit targets.
IA64 has got stubs for ia32_reg.c.
Known limitations: a 5.x/6.x gdb uses get/setcontext(), which isn't
implemented in the 32/64 wrapper yet. We also make a tiny patch to
gdb pacify it over conflicting formats of ld-elf.so.1.
Approved by: re
copies arguments into the kernel space and one that operates
completely in the kernel space;
o use kernel-only version of execve(2) to kill another stackgap in
linuxlator/i386.
Obtained from: DragonFlyBSD (partially)
MFC after: 2 weeks
to allow dumping per-thread machine specific notes. On ia64 we use this
function to flush the dirty registers onto the backingstore before we
write out the PRSTATUS notes.
Tested on: alpha, amd64, i386, ia64 & sparc64
Not tested on: arm, powerpc
time now to break with the past: do not write the PID in the first note.
Rationale:
1. [impact of the breakage] Process IDs in core files serve no immediate
purpose to the debugger itself. They are only useful to relate a core
file to a process. This can provide context to the person looking at
the core file, provided one keeps track of this. Overall, not having
the PID in the core file is only in very rare occasions unfortunate.
2. [reason of the breakage] Having one PRSTATUS note contain the PID,
while all others contain the LWPID of the corresponding kernel thread
creates an irregularity for the debugger that cannot easily be worked
around. This is caused by libthread_db correlating user thread IDs to
kernel thread (aka LWP) IDs and thus aware of the actual LWPIDs.
Update comments accordingly.
The overhead of unconditionally allocating TIDs (and likewise,
unconditionally deallocating them), is amortized across multiple
thread creations by the way UMA makes it possible to have type-stable
storage.
Previously the cost was kept down by having threads created as part
of a fork operation use the process' PID as the TID. While this had
some nice properties, it also introduced complexity in the way TIDs
were allocated. Most importantly, by using the type-stable storage
that UMA gives us this was also unnecessary.
This change affects how core dumps are created and in particular how
the PRSTATUS notes are dumped. Since we don't have a thread with a
TID equalling the PID, we now need a different way to preserve the
old and previous behavior. We do this by having the given thread (i.e.
the thread passed to the core dump code in td) dump it's state first
and fill in pr_pid with the actual PID. All other threads will have
pr_pid contain their TIDs. The upshot of all this is that the debugger
will now likely select the right LWP (=TID) as the initial thread.
Credits to: julian@ for spotting how we can utilize UMA.
Thanks to: all who provided julian@ with test results.
size_t and size_t *, respectively. Update callers for the new interface.
This is a better fix for overflows that occurred when dumping segments
larger than 2GB to core files.
equal to the process ID) is still present when we dump a core. It
already may have been destroyed. In that case we would end up
dereferencing a NULL pointer, so specifically test for that as well.
Reported & tested by: Dan Nelson <dnelson@allantgroup.com>
in the process. This is required for proper debugging of corefiles
created by 1:1 or M:N threaded processes. Add an XXX comment where
we should actually call a function that dumps MD specific notes.
An example of a MD specific note is the NT_PRXFPREG note for SSE
registers.
Since BFD creates non-annotated pseudo-sections for the first PRSTATUS
and FPREGSET notes (non-annotated in the sense that the name of the
section does not contain the pid/tid), make sure those sections describe
the initial thread of the process (i.e. the thread which tid equals the
pid). This is not strictly necessary, but makes sure that tools that use
the non-annotated section names will not change behaviour due to this
change.
The practical upshot of this all is that one can see the threads in
the debugger when looking at a corefile. For 1:1 threading this means
that *all* threads are visible.
entry size and the ELF version. Also, avoid a potential integer
overflow when determining whether the ELF header fits entirely
within the first page.
Reviewed by: jdp
A panic when attempting to execute an ELF binary with a bogus program
header table entry size was
Reported by: Christer Öberg <christer.oberg@texonet.com>
- 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
