x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
seccomp_init(3) libseccomp Documentation seccomp_init(3)
NAME
seccomp_init, seccomp_reset - Initialize the seccomp filter state
SYNOPSIS
#include <seccomp.h>
typedef void * scmp_filter_ctx;
scmp_filter_ctx seccomp_init(uint32_t def_action);
int seccomp_reset(scmp_filter_ctx ctx, uint32_t def_action);
Link with -lseccomp.
DESCRIPTION
The seccomp_init() and seccomp_reset() functions (re)initialize the in-
ternal seccomp filter state, prepares it for use, and sets the default
action based on the def_action parameter. The seccomp_init() function
must be called before any other libseccomp functions as the rest of the
library API will fail if the filter context is not initialized prop-
erly. The seccomp_reset() function releases the existing filter con-
text state before reinitializing it and can only be called after a call
to seccomp_init() has succeeded. If seccomp_reset() is called with a
NULL filter, it resets the library's global task state, including any
notification file descriptors retrieved by seccomp_notify_fd(3). Nor-
mally this is not needed, but it may be required to continue using the
library after a fork() or clone() call to ensure the API level and user
notification state is properly reset.
When the caller is finished configuring the seccomp filter and has
loaded it into the kernel, the caller should call seccomp_release(3) to
release all of the filter context state.
Valid def_action values are as follows:
SCMP_ACT_KILL
The thread will be terminated by the kernel with SIGSYS when it
calls a syscall that does not match any of the configured sec-
comp filter rules. The thread will not be able to catch the
signal.
SCMP_ACT_KILL_PROCESS
The entire process will be terminated by the kernel with SIGSYS
when it calls a syscall that does not match any of the config-
ured seccomp filter rules.
SCMP_ACT_TRAP
The thread will be sent a SIGSYS signal when it calls a syscall
that does not match any of the configured seccomp filter rules.
It may catch this and change its behavior accordingly. When us-
ing SA_SIGINFO with sigaction(2), si_code will be set to
SYS_SECCOMP, si_syscall will be set to the syscall that failed
the rules, and si_arch will be set to the AUDIT_ARCH for the ac-
tive ABI.
SCMP_ACT_ERRNO(uint16_t errno)
The thread will receive a return value of errno when it calls a
syscall that does not match any of the configured seccomp filter
rules.
SCMP_ACT_TRACE(uint16_t msg_num)
If the thread is being traced and the tracing process specified
the PTRACE_O_TRACESECCOMP option in the call to ptrace(2), the
tracing process will be notified, via PTRACE_EVENT_SECCOMP, and
the value provided in msg_num can be retrieved using the
PTRACE_GETEVENTMSG option.
SCMP_ACT_LOG
The seccomp filter will have no effect on the thread calling the
syscall if it does not match any of the configured seccomp fil-
ter rules but the syscall will be logged.
SCMP_ACT_ALLOW
The seccomp filter will have no effect on the thread calling the
syscall if it does not match any of the configured seccomp fil-
ter rules.
RETURN VALUE
The seccomp_init() function returns a filter context on success, NULL
on failure. The seccomp_reset() function returns zero on success or
one of the following error codes on failure:
-EINVAL
Invalid input, either the context or action is invalid.
-ENOMEM
The library was unable to allocate enough memory.
EXAMPLES
#include <seccomp.h>
int main(int argc, char *argv[])
{
int rc = -1;
scmp_filter_ctx ctx;
ctx = seccomp_init(SCMP_ACT_KILL);
if (ctx == NULL)
goto out;
/* ... */
rc = seccomp_reset(ctx, SCMP_ACT_KILL);
if (rc < 0)
goto out;
/* ... */
out:
seccomp_release(ctx);
return -rc;
}
NOTES
While the seccomp filter can be generated independent of the kernel,
kernel support is required to load and enforce the seccomp filter gen-
erated by libseccomp.
The libseccomp project site, with more information and the source code
repository, can be found at https://github.com/seccomp/libseccomp.
This tool, as well as the libseccomp library, is currently under devel-
opment, please report any bugs at the project site or directly to the
author.
AUTHOR
Paul Moore <paul@paul-moore.com>
SEE ALSO
seccomp_release(3)
paul@paul-moore.com 30 May 2020 seccomp_init(3)
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