I have to note that POSIX is simply stupid in how it describes O_EXEC/fexecve
and friends. Yes, not only inconsistent, but stupid.
In the open(2) description, O_RDONLY flag is described as:
O_RDONLY Open for reading only.
Taken from:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html
Note "for reading only". Not "for reading or executing"!
In the fexecve(2) description you can find:
The fexecve() function shall fail if:
[EBADF]
The fd argument is not a valid file descriptor open for executing.
Taken from:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html
As you can see the function shall fail if the file was not open with O_EXEC!
And yet, if you look closer you can find this mess in the exec.html:
Since execute permission is checked by fexecve(), the file description
fd need not have been opened with the O_EXEC flag.
Yes, O_EXEC flag doesn't have to be specified after all. You can open a file
with O_RDONLY and you still be able to fexecve(2) it.
Well, in theory we can pass those two flags, because O_RDONLY is 0,
but we won't be able to read from a descriptor opened with O_EXEC.
Update the comment.
Sponsored by: FreeBSD Foundation
MFC after: 2 weeks
While here return EBADF for descriptors opened for writing (previously it was ETXTBSY).
Add fgetvp_exec function which performs appropriate checks.
PR: kern/169651
In collaboration with: kib
Approved by: trasz (mentor)
MFC after: 1 week
the scheduled task from tc_windup(). Do it directly from tc_windup in
interrupt context [1].
Establish the permanent mapping of the shared page into the kernel
address space, avoiding the potential need to sleep waiting for
allocation of sf buffer during vdso_timehands update. As a
consequence, shared_page_write_start() and shared_page_write_end()
functions are not needed anymore.
Guess and memorize the pointers to native host and compat32 sysentvec
during initialization, to avoid the need to get shared_page_alloc_sx
lock during the update.
In tc_fill_vdso_timehands(), do not loop waiting for timehands
generation to stabilize, since vdso_timehands is written in the same
interrupt context which wrote timehands.
Requested by: mav [1]
MFC after: 29 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
Do not rely on the busy state of the page from which we allocate the
chunk, to protect allocator state. Use statically allocated sx lock
instead.
Provide more flexible KPI. In particular, allow to allocate chunk
without providing initial data, and allow writes into existing
allocation. Allow to get an sf buf which temporary maps the chunk, to
allow sequential updates to shared page content without unmapping in
between.
Reviewed by: jhb
Tested by: flo
MFC after: 1 month
the cached name used for KTR_SCHED traces when a thread's name changes.
This way KTR_SCHED traces (and thus schedgraph) will notice when a thread's
name changes, most commonly via execve().
MFC after: 2 weeks
syscall exit path. Otherwise, if SIGTRAP is ignored, that tdsendsignal()
do not want to deliver the signal, and debugger never get a notification
of exec.
Found and tested by: Anton Yuzhaninov <citrin citrin ru>
Discussed with: jhb
MFC after: 2 weeks
patch modifies makesyscalls.sh to prefix all of the non-compatibility
calls (e.g. not linux_, freebsd32_) with sys_ and updates the kernel
entry points and all places in the code that use them. It also
fixes an additional name space collision between the kernel function
psignal and the libc function of the same name by renaming the kernel
psignal kern_psignal(). By introducing this change now we will ease future
MFCs that change syscalls.
Reviewed by: rwatson
Approved by: re (bz)
kernel for FreeBSD 9.0:
Add a new capability mask argument to fget(9) and friends, allowing system
call code to declare what capabilities are required when an integer file
descriptor is converted into an in-kernel struct file *. With options
CAPABILITIES compiled into the kernel, this enforces capability
protection; without, this change is effectively a no-op.
Some cases require special handling, such as mmap(2), which must preserve
information about the maximum rights at the time of mapping in the memory
map so that they can later be enforced in mprotect(2) -- this is done by
narrowing the rights in the existing max_protection field used for similar
purposes with file permissions.
In namei(9), we assert that the code is not reached from within capability
mode, as we're not yet ready to enforce namespace capabilities there.
This will follow in a later commit.
Update two capability names: CAP_EVENT and CAP_KEVENT become
CAP_POST_KEVENT and CAP_POLL_KEVENT to more accurately indicate what they
represent.
Approved by: re (bz)
Submitted by: jonathan
Sponsored by: Google Inc
may be jointly referenced via the mask CTLFLAG_CAPRW. Sysctls with these
flags are available in Capsicum's capability mode; other sysctl nodes are
not.
Flag several useful sysctls as available in capability mode, such as memory
layout sysctls required by the run-time linker and malloc(3). Also expose
access to randomness and available kernel features.
A few sysctls are enabled to support name->MIB conversion; these may leak
information to capability mode by virtue of providing resolution on names
not flagged for access in capability mode. This is, generally, not a huge
problem, but might be something to resolve in the future. Flag these cases
with XXX comments.
Submitted by: jonathan
Sponsored by: Google, Inc.
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)
traced process by adding two new events which records value of process
sv_flags to the trace file at process creation/execing/exiting time.
MFC after: 1 Month.
setting SV_SHP flag and providing pointer to the vm object and mapping
address. Provide simple allocator to carve space in the page, tailored
to put the code with alignment restrictions.
Enable shared page use for amd64, both native and 32bit FreeBSD
binaries. Page is private mapped at the top of the user address
space, moving a start of the stack one page down. Move signal
trampoline code from the top of the stack to the shared page.
Reviewed by: alc
may be left. This fixes a memory leak that can occur when tracing is
disabled on a process via disabling tracing of a specific file (or if
an I/O error occurs with the tracefile) if the process's next system
call is exit(). The trace disabling code clears p_traceflag, so exit1()
doesn't do any KTRACE-related cleanup leading to the leak. I chose to
make the free'ing of pending records synchronous rather than patching
exit1().
- Move KTRACE-specific logic out of kern_(exec|exit|fork).c and into
kern_ktrace.c instead. Make ktrace_mtx private to kern_ktrace.c as a
result.
MFC after: 1 month
least one execute bit set, otherwise execve(2) will return EACCES even
for an user with PRIV_VFS_EXEC privilege.
Add the check also to vaccess(9), vaccess_acl_nfs4(9) and
vaccess_acl_posix1e(9). This makes access(2) to better agree with
execve(2). Because ZFS doesn't use vaccess(9) for VEXEC, add the check
to zfs_freebsd_access() too. There may be other file systems which are
not using vaccess*() functions and need to be handled separately.
PR: kern/125009
Reviewed by: bde, trasz
Approved by: pjd (ZFS part)
use '-' in probe names, matching the probe names in Solaris.[1]
Add userland SDT probes definitions to sys/sdt.h.
Sponsored by: The FreeBSD Foundation
Discussed with: rwaston [1]
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
details of the string buffer allocation in one place.
Eliminate the portion of the string buffer that was dedicated to storing
the interpreter name. The pointer to the interpreter name can simply be
made to point to the appropriate argument string.
Reviewed by: kib
shell command are stored in exec*()'s demand-paged string buffer. For
a "buildworld" on an 8GB amd64 multiprocessor, the new order reduces
the number of global TLB shootdowns by 31%. It also eliminates about
330k page faults on the kernel address space.
Change exec_shell_imgact() to use "args->begin_argv" consistently as
the start of the argument and environment strings. Previously, it
would sometimes use "args->buf", which is the start of the overall
buffer, but no longer the start of the argument and environment
strings. While I'm here, eliminate unnecessary passing of "&length"
to copystr(), where we don't actually care about the length of the
copied string.
Clean up the initialization of the exec map. In particular, use the
correct size for an entry, and express that size in the same way that
is used when an entry is allocated. The old size was one page too
large. (This discrepancy originated in 2004 when I rewrote
exec_map_first_page() to use sf_buf_alloc() instead of the exec map
for mapping the first page of the executable.)
Reviewed by: kib
- Rename tdsignal() to tdsendsignal() and make it private to kern_sig.c.
- Add tdsignal() and tdksignal() routines that mirror psignal() and
pksignal() except that they accept a thread as an argument instead of
a process. They send a signal to a specific thread rather than to an
individual process.
Reviewed by: kib
Extend struct sysvec with three new elements:
sv_fetch_syscall_args - the method to fetch syscall arguments from
usermode into struct syscall_args. The structure is machine-depended
(this might be reconsidered after all architectures are converted).
sv_set_syscall_retval - the method to set a return value for usermode
from the syscall. It is a generalization of
cpu_set_syscall_retval(9) to allow ABIs to override the way to set a
return value.
sv_syscallnames - the table of syscall names.
Use sv_set_syscall_retval in kern_sigsuspend() instead of hardcoding
the call to cpu_set_syscall_retval().
The new functions syscallenter(9) and syscallret(9) are provided that
use sv_*syscall* pointers and contain the common repeated code from
the syscall() implementations for the architecture-specific syscall
trap handlers.
Syscallenter() fetches arguments, calls syscall implementation from
ABI sysent table, and set up return frame. The end of syscall
bookkeeping is done by syscallret().
Take advantage of single place for MI syscall handling code and
implement ptrace_lwpinfo pl_flags PL_FLAG_SCE, PL_FLAG_SCX and
PL_FLAG_EXEC. The SCE and SCX flags notify the debugger that the
thread is stopped at syscall entry or return point respectively. The
EXEC flag augments SCX and notifies debugger that the process address
space was changed by one of exec(2)-family syscalls.
The i386, amd64, sparc64, sun4v, powerpc and ia64 syscall()s are
changed to use syscallenter()/syscallret(). MIPS and arm are not
converted and use the mostly unchanged syscall() implementation.
Reviewed by: jhb, marcel, marius, nwhitehorn, stas
Tested by: marcel (ia64), marius (sparc64), nwhitehorn (powerpc),
stas (mips)
MFC after: 1 month
managed pages that didn't already have that lock held. (Freeing an
unmanaged page, such as the various pmaps use, doesn't require the page
lock.)
This allows a change in vm_page_remove()'s locking requirements. It now
expects the page lock to be held instead of the page queues lock.
Consequently, the page queues lock is no longer required at all by callers
to vm_page_rename().
Discussed with: kib
architecture from page queue lock to a hashed array of page locks
(based on a patch by Jeff Roberson), I've implemented page lock
support in the MI code and have only moved vm_page's hold_count
out from under page queue mutex to page lock. This changes
pmap_extract_and_hold on all pmaps.
Supported by: Bitgravity Inc.
Discussed with: alc, jeffr, and kib
to the image_params struct instead of several members of that struct
individually. This makes it easier to expand its arguments in the future
without touching all platforms.
Reviewed by: jhb
so should be copied to userspace with suword32() instead of suword().
This alleviates problems on 64-bit big-endian architectures, and is a
no-op on all 32-bit architectures.
Tested on: amd64, sparc64, powerpc64
td_name[] arrays are actually MAXCOMLEN + 1 in size and a few places that
created shadow copies of these arrays were just using MAXCOMLEN.
- Prefer using sizeof() of an array type to explicit constants for the
array length in a few places.
- Ensure that all of p_comm[] and td_name[] is always zero'd during
execve() to guard against any possible information leaks. Previously
trailing garbage in p_comm[] could be leaked to userland in ktrace
record headers via td_name[].
Reviewed by: bde
virtual address 0, limiting the ability to convert a kernel
NULL pointer dereference into a privilege escalation attack.
If the sysctl is set to 0 a newly started process will not be able
to map anything in the address range of the first page (0 to PAGE_SIZE).
This is the default. Already running processes are not affected by this.
You can either change the sysctl or the tunable from loader in case
you need to map at a virtual address of 0, for example when running
any of the extinct species of a set of a.out binaries, vm86 emulation, ..
In that case set security.bsd.map_at_zero="1".
Superseeds: r197537
In collaboration with: jhb, kib, alc
The hook calls vn_fullpath(9), that should not be executed with a vnode
lock held.
Reported by: Bruce Cran <bruce cran org uk>
Tested by: pho
MFC after: 3 days
- Don't grab the filedesc lock just to read fd_cmask.
- Drop vnode locks earlier when mounting the root filesystem and before
sanitizing stdin/out/err file descriptors during execve().
Submitted by: kib
Approved by: re (rwatson)
MFC after: 1 week
to avoid exposing ARG_ macros/flag values outside of the audit code in
order to name which one of two possible vnodes will be audited for a
system call.
Approved by: re (kib)
Obtained from: TrustedBSD Project
MFC after: 1 month
specific macros for each audit argument type. This makes it easier to
follow call-graphs, especially for automated analysis tools (such as
fxr).
In MFC, we should leave the existing AUDIT_ARG() macros as they may be
used by third-party kernel modules.
Suggested by: brooks
Approved by: re (kib)
Obtained from: TrustedBSD Project
MFC after: 1 week
NGROUPS_MAX, eliminate ABI dependencies on them, and raise the to 1024
and 1023 respectively. (Previously they were equal, but under a close
reading of POSIX, NGROUPS_MAX was defined to be too large by 1 since it
is the number of supplemental groups, not total number of groups.)
The bulk of the change consists of converting the struct ucred member
cr_groups from a static array to a pointer. Do the equivalent in
kinfo_proc.
Introduce new interfaces crcopysafe() and crsetgroups() for duplicating
a process credential before modifying it and for setting group lists
respectively. Both interfaces take care for the details of allocating
groups array. crsetgroups() takes care of truncating the group list
to the current maximum (NGROUPS) if necessary. In the future,
crsetgroups() may be responsible for insuring invariants such as sorting
the supplemental groups to allow groupmember() to be implemented as a
binary search.
Because we can not change struct xucred without breaking application
ABIs, we leave it alone and introduce a new XU_NGROUPS value which is
always 16 and is to be used or NGRPS as appropriate for things such as
NFS which need to use no more than 16 groups. When feasible, truncate
the group list rather than generating an error.
Minor changes:
- Reduce the number of hand rolled versions of groupmember().
- Do not assign to both cr_gid and cr_groups[0].
- Modify ipfw to cache ucreds instead of part of their contents since
they are immutable once referenced by more than one entity.
Submitted by: Isilon Systems (initial implementation)
X-MFC after: never
PR: bin/113398 kern/133867
and used in a large number of files, but also because an increasing number
of incorrect uses of MAC calls were sneaking in due to copy-and-paste of
MAC-aware code without the associated opt_mac.h include.
Discussed with: pjd
Inside do_execve(), we have a pointer `ndp', which always points to
`&nd'. I can imagine a primitive (non-optimizing) compiler to really
reserve space for such a pointer, so just remove the variable and use
`&nd' directly.
kern_time.c:
- Unused variable `p'.
kern_thr.c:
- Variable `error' is always caught immediately, so no reason to
initialize it. There is no way that error != 0 at the end of
create_thread().
kern_sig.c:
- Unused variable `code'.
kern_synch.c:
- `rval' is always assigned in all different cases.
kern_rwlock.c:
- `v' is always overwritten with RW_UNLOCKED further on.
kern_malloc.c:
- `size' is always initialized with the proper value before being used.
kern_exit.c:
- `error' is always caught and returned immediately. abort2() never
returns a non-zero value.
kern_exec.c:
- `len' is always assigned inside the if-statement right below it.
tty_info.c:
- `td' is always overwritten by FOREACH_THREAD_IN_PROC().
Found by: LLVM's scan-build
parent threads sleep on the parent' struct proc until corresponding
child releases the vmspace. Each sleep is interlocked with proc mutex of
the child, that triggers assertion in the sleepq_add(). The assertion
requires that at any time, all simultaneous sleepers for the channel use
the same interlock.
Silent the assertion by using conditional variable allocated in the
child. Broadcast the variable event on exec() and exit().
Since struct proc * sleep wait channel is overloaded for several
unrelated events, I was unable to remove wakeups from the places where
cv_broadcast() is added, except exec().
Reported and tested by: ganbold
Suggested and reviewed by: jhb
MFC after: 2 week
