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PRCTL(2) Linux Programmer's Manual PRCTL(2)
prctl - operations on a process
#include <sys/prctl.h>
int prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
prctl() is called with a first argument describing what to do (with
values defined in <linux/prctl.h>), and further arguments with a
significance depending on the first one. The first argument can be:
PR_CAPBSET_READ (since Linux 2.6.25)
Return (as the function result) 1 if the capability specified
in arg2 is in the calling thread's capability bounding set, or
0 if it is not. (The capability constants are defined in
<linux/capability.h>.) The capability bounding set dictates
whether the process can receive the capability through a
file's permitted capability set on a subsequent call to
execve(2).
If the capability specified in arg2 is not valid, then the
call fails with the error EINVAL.
PR_CAPBSET_DROP (since Linux 2.6.25)
If the calling thread has the CAP_SETPCAP capability, then
drop the capability specified by arg2 from the calling
thread's capability bounding set. Any children of the calling
thread will inherit the newly reduced bounding set.
The call fails with the error: EPERM if the calling thread
does not have the CAP_SETPCAP; EINVAL if arg2 does not
represent a valid capability; or EINVAL if file capabilities
are not enabled in the kernel, in which case bounding sets are
not supported.
PR_SET_CHILD_SUBREAPER (since Linux 3.4)
If arg2 is nonzero, set the "child subreaper" attribute of the
calling process; if arg2 is zero, unset the attribute. When a
process is marked as a child subreaper, all of the children
that it creates, and their descendants, will be marked as
having a subreaper. In effect, a subreaper fulfills the role
of init(1) for its descendant processes. Upon termination of
a process that is orphaned (i.e., its immediate parent has
already terminated) and marked as having a subreaper, the
nearest still living ancestor subreaper will receive a SIGCHLD
signal and be able to wait(2) on the process to discover its
termination status.
PR_GET_CHILD_SUBREAPER (since Linux 3.4)
Return the "child subreaper" setting of the caller, in the
location pointed to by (int *) arg2.
PR_SET_DUMPABLE (since Linux 2.3.20)
Set the state of the "dumpable" flag, which determines whether
core dumps are produced for the calling process upon delivery
of a signal whose default behavior is to produce a core dump.
In kernels up to and including 2.6.12, arg2 must be either 0
(SUID_DUMP_DISABLE, process is not dumpable) or 1
(SUID_DUMP_USER, process is dumpable). Between kernels 2.6.13
and 2.6.17, the value 2 was also permitted, which caused any
binary which normally would not be dumped to be dumped
readable by root only; for security reasons, this feature has
been removed. (See also the description of /proc/sys/fs/
suid_dumpable in proc(5).)
Normally, this flag is set to 1. However, it is reset to the
current value contained in the file /proc/sys/fs/suid_dumpable
(which by default has the value 0), if any of the following
attributes of the process are changed by the operations listed
below:
* The effective user or group ID is changed.
* The filesystem user or group ID is changed (see
credentials(7)).
* The process's set of permitted capabilities (see
capabilities(7)) is changed such that its new set of
capabilities is not a subset of its previous set of
capabilities.
The operations that may trigger changes to the dumpable flag
include:
* execution (execve(2)) of a set-user-ID or set-group-ID
program, or a program that has capabilities (see
capabilities(7));
* capset(2); and
* system calls that change process credentials (setuid(2)
setgid(2), setresuid(2), setresgid(2), setgroups(2), and so
on).
Processes that are not dumpable can not be attached via
ptrace(2) PTRACE_ATTACH.
PR_GET_DUMPABLE (since Linux 2.3.20)
Return (as the function result) the current state of the
calling process's dumpable flag.
PR_SET_ENDIAN (since Linux 2.6.18, PowerPC only)
Set the endian-ness of the calling process to the value given
in arg2, which should be one of the following: PR_ENDIAN_BIG,
PR_ENDIAN_LITTLE, or PR_ENDIAN_PPC_LITTLE (PowerPC pseudo
little endian).
PR_GET_ENDIAN (since Linux 2.6.18, PowerPC only)
Return the endian-ness of the calling process, in the location
pointed to by (int *) arg2.
PR_SET_FPEMU (since Linux 2.4.18, 2.5.9, only on ia64)
Set floating-point emulation control bits to arg2. Pass
PR_FPEMU_NOPRINT to silently emulate floating-point operation
accesses, or PR_FPEMU_SIGFPE to not emulate floating-point
operations and send SIGFPE instead.
PR_GET_FPEMU (since Linux 2.4.18, 2.5.9, only on ia64)
Return floating-point emulation control bits, in the location
pointed to by (int *) arg2.
PR_SET_FPEXC (since Linux 2.4.21, 2.5.32, only on PowerPC)
Set floating-point exception mode to arg2. Pass
PR_FP_EXC_SW_ENABLE to use FPEXC for FP exception enables,
PR_FP_EXC_DIV for floating-point divide by zero, PR_FP_EXC_OVF
for floating-point overflow, PR_FP_EXC_UND for floating-point
underflow, PR_FP_EXC_RES for floating-point inexact result,
PR_FP_EXC_INV for floating-point invalid operation,
PR_FP_EXC_DISABLED for FP exceptions disabled,
PR_FP_EXC_NONRECOV for async nonrecoverable exception mode,
PR_FP_EXC_ASYNC for async recoverable exception mode,
PR_FP_EXC_PRECISE for precise exception mode.
PR_GET_FPEXC (since Linux 2.4.21, 2.5.32, only on PowerPC)
Return floating-point exception mode, in the location pointed
to by (int *) arg2.
PR_SET_KEEPCAPS (since Linux 2.2.18)
Set the state of the thread's "keep capabilities" flag, which
determines whether the threads's permitted capability set is
cleared when a change is made to the threads's user IDs such
that the threads's real UID, effective UID, and saved set-
user-ID all become nonzero when at least one of them
previously had the value 0. By default, the permitted
capability set is cleared when such a change is made; setting
the "keep capabilities" flag prevents it from being cleared.
arg2 must be either 0 (permitted capabilities are cleared) or
1 (permitted capabilities are kept). (A thread's effective
capability set is always cleared when such a credential change
is made, regardless of the setting of the "keep capabilities"
flag.) The "keep capabilities" value will be reset to 0 on
subsequent calls to execve(2).
PR_GET_KEEPCAPS (since Linux 2.2.18)
Return (as the function result) the current state of the
calling threads's "keep capabilities" flag.
PR_SET_NAME (since Linux 2.6.9)
Set the name of the calling thread, using the value in the
location pointed to by (char *) arg2. The name can be up to
16 bytes long, including the terminating null byte. (If the
length of the string, including the terminating null byte,
exceeds 16 bytes, the string is silently truncated.) This is
the same attribute that can be set via pthread_setname_np(3)
and retrieved using pthread_getname_np(3). The attribute is
likewise accessible via /proc/self/task/[tid]/comm, where tid
is the name of the calling thread.
PR_GET_NAME (since Linux 2.6.11)
Return the name of the calling thread, in the buffer pointed
to by (char *) arg2. The buffer should allow space for up to
16 bytes; the returned string will be null-terminated.
PR_SET_NO_NEW_PRIVS (since Linux 3.5)
Set the calling process's no_new_privs bit to the value in
arg2. With no_new_privs set to 1, execve(2) promises not to
grant privileges to do anything that could not have been done
without the execve(2) call (for example, rendering the set-
user-ID and set-group-ID mode bits, and file capabilities non-
functional). Once set, this bit cannot be unset. The setting
of this bit is inherited by children created by fork(2) and
clone(2), and preserved across execve(2).
For more information, see the kernel source file
Documentation/prctl/no_new_privs.txt.
PR_GET_NO_NEW_PRIVS (since Linux 3.5)
Return (as the function result) the value of the no_new_privs
bit for the current process. A value of 0 indicates the
regular execve(2) behavior. A value of 1 indicates execve(2)
will operate in the privilege-restricting mode described
above.
PR_SET_PDEATHSIG (since Linux 2.1.57)
Set the parent death signal of the calling process to arg2
(either a signal value in the range 1..maxsig, or 0 to clear).
This is the signal that the calling process will get when its
parent dies. This value is cleared for the child of a fork(2)
and (since Linux 2.4.36 / 2.6.23) when executing a set-user-ID
or set-group-ID binary, or a binary that has associated
capabilities (see capabilities(7)). This value is preserved
across execve(2).
Warning: the "parent" in this case is considered to be the
thread that created this process. In other words, the signal
will be sent when that thread terminates (via, for example,
pthread_exit(3)), rather than after all of the threads in the
parent process terminate.
PR_GET_PDEATHSIG (since Linux 2.3.15)
Return the current value of the parent process death signal,
in the location pointed to by (int *) arg2.
PR_SET_PTRACER (since Linux 3.4)
This is meaningful only when the Yama LSM is enabled and in
mode 1 ("restricted ptrace", visible via
/proc/sys/kernel/yama/ptrace_scope). When a "ptracer process
ID" is passed in arg2, the caller is declaring that the
ptracer process can ptrace(2) the calling process as if it
were a direct process ancestor. Each PR_SET_PTRACER operation
replaces the previous "ptracer process ID". Employing
PR_SET_PTRACER with arg2 set to 0 clears the caller's "ptracer
process ID". If arg2 is PR_SET_PTRACER_ANY, the ptrace
restrictions introduced by Yama are effectively disabled for
the calling process.
For further information, see the kernel source file
Documentation/security/Yama.txt.
PR_SET_SECCOMP (since Linux 2.6.23)
Set the secure computing (seccomp) mode for the calling
thread, to limit the available system calls. The more recent
seccomp(2) system call provides a superset of the
functionality of PR_SET_SECCOMP.
The seccomp mode is selected via arg2. (The seccomp constants
are defined in <linux/seccomp.h>.)
With arg2 set to SECCOMP_MODE_STRICT, the only system calls
that the thread is permitted to make are read(2), write(2),
_exit(2) (but not exit_group(2)), and sigreturn(2). Other
system calls result in the delivery of a SIGKILL signal.
Strict secure computing mode is useful for number-crunching
applications that may need to execute untrusted byte code,
perhaps obtained by reading from a pipe or socket. This
operation is available only if the kernel is configured with
CONFIG_SECCOMP enabled.
With arg2 set to SECCOMP_MODE_FILTER (since Linux 3.5), the
system calls allowed are defined by a pointer to a Berkeley
Packet Filter passed in arg3. This argument is a pointer to
struct sock_fprog; it can be designed to filter arbitrary
system calls and system call arguments. This mode is
available only if the kernel is configured with
CONFIG_SECCOMP_FILTER enabled.
If SECCOMP_MODE_FILTER filters permit fork(2), then the
seccomp mode is inherited by children created by fork(2); if
execve(2) is permitted, then the seccomp mode is preserved
across execve(2). If the filters permit prctl() calls, then
additional filters can be added; they are run in order until
the first non-allow result is seen.
For further information, see the kernel source file
Documentation/prctl/seccomp_filter.txt.
PR_GET_SECCOMP (since Linux 2.6.23)
Return (as the function result) the secure computing mode of
the calling thread. If the caller is not in secure computing
mode, this operation returns 0; if the caller is in strict
secure computing mode, then the prctl() call will cause a
SIGKILL signal to be sent to the process. If the caller is in
filter mode, and this system call is allowed by the seccomp
filters, it returns 2; otherwise, the process is killed with a
SIGKILL signal. This operation is available only if the
kernel is configured with CONFIG_SECCOMP enabled.
Since Linux 3.8, the Seccomp field of the /proc/[pid]/status
file provides a method of obtaining the same information,
without the risk that the process is killed; see proc(5).
PR_SET_SECUREBITS (since Linux 2.6.26)
Set the "securebits" flags of the calling thread to the value
supplied in arg2. See capabilities(7).
PR_GET_SECUREBITS (since Linux 2.6.26)
Return (as the function result) the "securebits" flags of the
calling thread. See capabilities(7).
PR_SET_THP_DISABLE (since Linux 3.15)
Set the state of the "THP disable" flag for the calling
thread. If arg2 has a nonzero value, the flag is set,
otherwise it is cleared. Setting this flag provides a method
for disabling transparent huge pages for jobs where the code
cannot be modified, and using a malloc hook with madvise(2) is
not an option (i.e., statically allocated data). The setting
of the "THP disable" flag is inherited by a child created via
fork(2) and is preserved across execve(2).
PR_GET_THP_DISABLE (since Linux 3.15)
Return (via the function result) the current setting of the
"THP disable" flag for the calling thread: either 1, if the
flag is set, or 0, if it is not.
PR_GET_TID_ADDRESS (since Linux 3.5)
Retrieve the clear_child_tid address set by set_tid_address(2)
and the clone(2) CLONE_CHILD_CLEARTID flag, in the location
pointed to by (int **) arg2. This feature is available only
if the kernel is built with the CONFIG_CHECKPOINT_RESTORE
option enabled.
PR_SET_TIMERSLACK (since Linux 2.6.28)
Set the current timer slack for the calling thread to the
nanosecond value supplied in arg2. If arg2 is less than or
equal to zero, reset the current timer slack to the thread's
default timer slack value. The timer slack is used by the
kernel to group timer expirations for the calling thread that
are close to one another; as a consequence, timer expirations
for the thread may be up to the specified number of
nanoseconds late (but will never expire early). Grouping
timer expirations can help reduce system power consumption by
minimizing CPU wake-ups.
The timer expirations affected by timer slack are those set by
select(2), pselect(2), poll(2), ppoll(2), epoll_wait(2),
epoll_pwait(2), clock_nanosleep(2), nanosleep(2), and futex(2)
(and thus the library functions implemented via futexes,
including pthread_cond_timedwait(3),
pthread_mutex_timedlock(3), pthread_rwlock_timedrdlock(3),
pthread_rwlock_timedwrlock(3), and sem_timedwait(3)).
Timer slack is not applied to threads that are scheduled under
a real-time scheduling policy (see sched_setscheduler(2)).
Each thread has two associated timer slack values: a "default"
value, and a "current" value. The current value is the one
that governs grouping of timer expirations. When a new thread
is created, the two timer slack values are made the same as
the current value of the creating thread. Thereafter, a
thread can adjust its current timer slack value via
PR_SET_TIMERSLACK (the default value can't be changed). The
timer slack values of init (PID 1), the ancestor of all
processes, are 50,000 nanoseconds (50 microseconds). The
timer slack values are preserved across execve(2).
PR_GET_TIMERSLACK (since Linux 2.6.28)
Return (as the function result) the current timer slack value
of the calling thread.
PR_SET_TIMING (since Linux 2.6.0-test4)
Set whether to use (normal, traditional) statistical process
timing or accurate timestamp-based process timing, by passing
PR_TIMING_STATISTICAL or PR_TIMING_TIMESTAMP to arg2.
PR_TIMING_TIMESTAMP is not currently implemented (attempting
to set this mode will yield the error EINVAL).
PR_GET_TIMING (since Linux 2.6.0-test4)
Return (as the function result) which process timing method is
currently in use.
PR_TASK_PERF_EVENTS_DISABLE (since Linux 2.6.31)
Disable all performance counters attached to the calling
process, regardless of whether the counters were created by
this process or another process. Performance counters created
by the calling process for other processes are unaffected.
For more information on performance counters, see the Linux
kernel source file tools/perf/design.txt.
Originally called PR_TASK_PERF_COUNTERS_DISABLE; renamed (with
same numerical value) in Linux 2.6.32.
PR_TASK_PERF_EVENTS_ENABLE (since Linux 2.6.31)
The converse of PR_TASK_PERF_EVENTS_DISABLE; enable
performance counters attached to the calling process.
Originally called PR_TASK_PERF_COUNTERS_ENABLE; renamed in
Linux 2.6.32.
PR_SET_TSC (since Linux 2.6.26, x86 only)
Set the state of the flag determining whether the timestamp
counter can be read by the process. Pass PR_TSC_ENABLE to
arg2 to allow it to be read, or PR_TSC_SIGSEGV to generate a
SIGSEGV when the process tries to read the timestamp counter.
PR_GET_TSC (since Linux 2.6.26, x86 only)
Return the state of the flag determining whether the timestamp
counter can be read, in the location pointed to by (int *)
arg2.
PR_SET_UNALIGN
(Only on: ia64, since Linux 2.3.48; parisc, since Linux
2.6.15; PowerPC, since Linux 2.6.18; Alpha, since Linux
2.6.22) Set unaligned access control bits to arg2. Pass
PR_UNALIGN_NOPRINT to silently fix up unaligned user accesses,
or PR_UNALIGN_SIGBUS to generate SIGBUS on unaligned user
access.
PR_GET_UNALIGN
(see PR_SET_UNALIGN for information on versions and
architectures) Return unaligned access control bits, in the
location pointed to by (int *) arg2.
PR_MCE_KILL (since Linux 2.6.32)
Set the machine check memory corruption kill policy for the
current thread. If arg2 is PR_MCE_KILL_CLEAR, clear the
thread memory corruption kill policy and use the system-wide
default. (The system-wide default is defined by
/proc/sys/vm/memory_failure_early_kill; see proc(5).) If arg2
is PR_MCE_KILL_SET, use a thread-specific memory corruption
kill policy. In this case, arg3 defines whether the policy is
early kill (PR_MCE_KILL_EARLY), late kill (PR_MCE_KILL_LATE),
or the system-wide default (PR_MCE_KILL_DEFAULT). Early kill
means that the thread receives a SIGBUS signal as soon as
hardware memory corruption is detected inside its address
space. In late kill mode, the process is killed only when it
accesses a corrupted page. See sigaction(2) for more
information on the SIGBUS signal. The policy is inherited by
children. The remaining unused prctl() arguments must be zero
for future compatibility.
PR_MCE_KILL_GET (since Linux 2.6.32)
Return the current per-process machine check kill policy. All
unused prctl() arguments must be zero.
PR_SET_MM (since Linux 3.3)
Modify certain kernel memory map descriptor fields of the
calling process. Usually these fields are set by the kernel
and dynamic loader (see ld.so(8) for more information) and a
regular application should not use this feature. However,
there are cases, such as self-modifying programs, where a
program might find it useful to change its own memory map.
This feature is available only if the kernel is built with the
CONFIG_CHECKPOINT_RESTORE option enabled. The calling process
must have the CAP_SYS_RESOURCE capability. The value in arg2
is one of the options below, while arg3 provides a new value
for the option.
PR_SET_MM_START_CODE
Set the address above which the program text can run.
The corresponding memory area must be readable and
executable, but not writable or sharable (see
mprotect(2) and mmap(2) for more information).
PR_SET_MM_END_CODE
Set the address below which the program text can run.
The corresponding memory area must be readable and
executable, but not writable or sharable.
PR_SET_MM_START_DATA
Set the address above which initialized and
uninitialized (bss) data are placed. The corresponding
memory area must be readable and writable, but not
executable or sharable.
PR_SET_MM_END_DATA
Set the address below which initialized and
uninitialized (bss) data are placed. The corresponding
memory area must be readable and writable, but not
executable or sharable.
PR_SET_MM_START_STACK
Set the start address of the stack. The corresponding
memory area must be readable and writable.
PR_SET_MM_START_BRK
Set the address above which the program heap can be
expanded with brk(2) call. The address must be greater
than the ending address of the current program data
segment. In addition, the combined size of the
resulting heap and the size of the data segment can't
exceed the RLIMIT_DATA resource limit (see
setrlimit(2)).
PR_SET_MM_BRK
Set the current brk(2) value. The requirements for the
address are the same as for the PR_SET_MM_START_BRK
option.
The following options are available since Linux 3.5.
PR_SET_MM_ARG_START
Set the address above which the program command line is
placed.
PR_SET_MM_ARG_END
Set the address below which the program command line is
placed.
PR_SET_MM_ENV_START
Set the address above which the program environment is
placed.
PR_SET_MM_ENV_END
Set the address below which the program environment is
placed.
The address passed with PR_SET_MM_ARG_START,
PR_SET_MM_ARG_END, PR_SET_MM_ENV_START, and
PR_SET_MM_ENV_END should belong to a process stack
area. Thus, the corresponding memory area must be
readable, writable, and (depending on the kernel
configuration) have the MAP_GROWSDOWN attribute set
(see mmap(2)).
PR_SET_MM_AUXV
Set a new auxiliary vector. The arg3 argument should
provide the address of the vector. The arg4 is the
size of the vector.
PR_SET_MM_EXE_FILE
Supersede the /proc/pid/exe symbolic link with a new
one pointing to a new executable file identified by the
file descriptor provided in arg3 argument. The file
descriptor should be obtained with a regular open(2)
call.
To change the symbolic link, one needs to unmap all
existing executable memory areas, including those
created by the kernel itself (for example the kernel
usually creates at least one executable memory area for
the ELF .text section).
The second limitation is that such transitions can be
done only once in a process life time. Any further
attempts will be rejected. This should help system
administrators monitor unusual symbolic-link
transitions over all processes running on a system.
PR_MPX_ENABLE_MANAGEMENT, PR_MPX_DISABLE_MANAGEMENT (since Linux
3.19)
Enable or disable kernel management of Memory Protection
eXtensions (MPX) bounds tables. The arg2, arg3, arg4, and
arg5 arguments must be zero.
MPX is a hardware-assisted mechanism for performing bounds
checking on pointers. It consists of a set of registers
storing bounds information and a set of special instruction
prefixes that tell the CPU on which instructions it should do
bounds enforcement. There is a limited number of these
registers and when there are more pointers than registers,
their contents must be "spilled" into a set of tables. These
tables are called "bounds tables" and the MPX prctl()
operations control whether the kernel manages their allocation
and freeing.
When management is enabled, the kernel will take over
allocation and freeing of the bounds tables. It does this by
trapping the #BR exceptions that result at first use of
missing bounds tables and instead of delivering the exception
to user space, it allocates the table and populates the bounds
directory with the location of the new table. For freeing,
the kernel checks to see if bounds tables are present for
memory which is not allocated, and frees them if so.
Before enabling MPX management using PR_MPX_ENABLE_MANAGEMENT,
the application must first have allocated a user-space buffer
for the bounds directory and placed the location of that
directory in the bndcfgu register.
These calls will fail if the CPU or kernel does not support
MPX. Kernel support for MPX is enabled via the
CONFIG_X86_INTEL_MPX configuration option. You can check
whether the CPU supports MPX by looking for the 'mpx' CPUID
bit, like with the following command:
cat /proc/cpuinfo | grep ' mpx '
A thread may not switch in or out of long (64-bit) mode while
MPX is enabled.
All threads in a process are affected by these calls.
The child of a fork(2) inherits the state of MPX management.
During execve(2), MPX management is reset to a state as if
PR_MPX_DISABLE_MANAGEMENT had been called.
For further information on Intel MPX, see the kernel source
file Documentation/x86/intel_mpx.txt.
On success, PR_GET_DUMPABLE, PR_GET_KEEPCAPS, PR_GET_NO_NEW_PRIVS,
PR_GET_THP_DISABLE, PR_CAPBSET_READ, PR_GET_TIMING,
PR_GET_TIMERSLACK, PR_GET_SECUREBITS, PR_MCE_KILL_GET, and (if it
returns) PR_GET_SECCOMP return the nonnegative values described
above. All other option values return 0 on success. On error, -1 is
returned, and errno is set appropriately.
EFAULT arg2 is an invalid address.
EFAULT option is PR_SET_SECCOMP, arg2 is SECCOMP_MODE_FILTER, the
system was built with CONFIG_SECCOMP_FILTER, and arg3 is an
invalid address.
EINVAL The value of option is not recognized.
EINVAL option is PR_MCE_KILL or PR_MCE_KILL_GET or PR_SET_MM, and
unused prctl() arguments were not specified as zero.
EINVAL arg2 is not valid value for this option.
EINVAL option is PR_SET_SECCOMP or PR_GET_SECCOMP, and the kernel was
not configured with CONFIG_SECCOMP.
EINVAL option is PR_SET_SECCOMP, arg2 is SECCOMP_MODE_FILTER, and the
kernel was not configured with CONFIG_SECCOMP_FILTER.
EINVAL option is PR_SET_MM, and one of the following is true
* arg4 or arg5 is nonzero;
* arg3 is greater than TASK_SIZE (the limit on the size of
the user address space for this architecture);
* arg2 is PR_SET_MM_START_CODE, PR_SET_MM_END_CODE,
PR_SET_MM_START_DATA, PR_SET_MM_END_DATA, or
PR_SET_MM_START_STACK, and the permissions of the
corresponding memory area are not as required;
* arg2 is PR_SET_MM_START_BRK or PR_SET_MM_BRK, and arg3 is
less than or equal to the end of the data segment or
specifies a value that would cause the RLIMIT_DATA resource
limit to be exceeded.
EINVAL option is PR_SET_PTRACER and arg2 is not 0,
PR_SET_PTRACER_ANY, or the PID of an existing process.
EINVAL option is PR_SET_PDEATHSIG and arg2 is not a valid signal
number.
EINVAL option is PR_SET_DUMPABLE and arg2 is neither
SUID_DUMP_DISABLE nor SUID_DUMP_USER.
EINVAL option is PR_SET_TIMING and arg2 is not PR_TIMING_STATISTICAL.
EINVAL option is PR_SET_NO_NEW_PRIVS and arg2 is not equal to 1 or
arg3, arg4, or arg5 is nonzero.
EINVAL option is PR_GET_NO_NEW_PRIVS and arg2, arg3, arg4, or arg5 is
nonzero.
EINVAL option is PR_SET_THP_DISABLE and arg3, arg4, or arg5 is
nonzero.
EINVAL option is PR_GET_THP_DISABLE and arg2, arg3, arg4, or arg5 is
nonzero.
EPERM option is PR_SET_SECUREBITS, and the caller does not have the
CAP_SETPCAP capability, or tried to unset a "locked" flag, or
tried to set a flag whose corresponding locked flag was set
(see capabilities(7)).
EPERM option is PR_SET_KEEPCAPS, and the callers's
SECURE_KEEP_CAPS_LOCKED flag is set (see capabilities(7)).
EPERM option is PR_CAPBSET_DROP, and the caller does not have the
CAP_SETPCAP capability.
EPERM option is PR_SET_MM, and the caller does not have the
CAP_SYS_RESOURCE capability.
EACCES option is PR_SET_MM, and arg3 is PR_SET_MM_EXE_FILE, the file
is not executable.
EBUSY option is PR_SET_MM, arg3 is PR_SET_MM_EXE_FILE, and this the
second attempt to change the /proc/pid/exe symbolic link,
which is prohibited.
EBADF option is PR_SET_MM, arg3 is PR_SET_MM_EXE_FILE, and the file
descriptor passed in arg4 is not valid.
ENXIO option was PR_MPX_ENABLE_MANAGEMENT or
PR_MPX_DISABLE_MANAGEMENT and the kernel or the CPU does not
support MPX management. Check that the kernel and processor
have MPX support.
The prctl() system call was introduced in Linux 2.1.57.
This call is Linux-specific. IRIX has a prctl() system call (also
introduced in Linux 2.1.44 as irix_prctl on the MIPS architecture),
with prototype
ptrdiff_t prctl(int option, int arg2, int arg3);
and options to get the maximum number of processes per user, get the
maximum number of processors the calling process can use, find out
whether a specified process is currently blocked, get or set the
maximum stack size, and so on.
signal(2), core(5)
This page is part of release 4.02 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
Linux 2015-05-07 PRCTL(2)
Copyright and license for this manual page
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HTML rendering created 2015-08-08 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.
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