[linux-seccomp.git] / libseccomp / doc / man / man3 / seccomp_init.3

.TH "seccomp_init" 3 "25 July 2012" "paul@paul-moore.com" "libseccomp Documentation"
.\" //////////////////////////////////////////////////////////////////////////
.SH NAME
.\" //////////////////////////////////////////////////////////////////////////
seccomp_init, seccomp_reset \- Initialize the seccomp filter state
.\" //////////////////////////////////////////////////////////////////////////
.SH SYNOPSIS
.\" //////////////////////////////////////////////////////////////////////////
.nf
.B #include <seccomp.h>
.sp
.B typedef void * scmp_filter_ctx;
.sp
.BI "scmp_filter_ctx seccomp_init(uint32_t " def_action ");"
.BI "int seccomp_reset(scmp_filter_ctx " ctx ", uint32_t " def_action ");"
.sp
Link with \fI\-lseccomp\fP.
.fi
.\" //////////////////////////////////////////////////////////////////////////
.SH DESCRIPTION
.\" //////////////////////////////////////////////////////////////////////////
.P
The
.BR seccomp_init ()
and
.BR seccomp_reset ()
functions (re)initialize the internal seccomp filter state, prepares it for
use, and sets the default action based on the
.I def_action
parameter.  The
.BR 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 properly.
The
.BR seccomp_reset ()
function releases the existing filter context state before reinitializing it
and can only be called after a call to
.BR seccomp_init ()
has succeeded.
.P
When the caller is finished configuring the seccomp filter and has loaded it
into the kernel, the caller should call
.BR seccomp_release (3)
to release all of the filter context state.
.P
Valid
.I def_action
values are as follows:
.TP
.B 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 seccomp filter rules.  The thread
will not be able to catch the signal.
.TP
.B 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 using SA_SIGINFO with
.BR 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 active ABI.
.TP
.B SCMP_ACT_ERRNO(uint16_t errno)
The thread will receive a return value of
.I errno
when it calls a syscall that does not match any of the configured seccomp filter
rules.
.TP
.B SCMP_ACT_TRACE(uint16_t msg_num)
If the thread is being traced and the tracing process specified the
.B PTRACE_O_TRACESECCOMP
option in the call to
.BR ptrace (2),
the tracing process will be notified, via
.BR PTRACE_EVENT_SECCOMP ,
and the value provided in
.I msg_num
can be retrieved using the
.B PTRACE_GETEVENTMSG
option.
.TP
.B 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 filter rules.
.\" //////////////////////////////////////////////////////////////////////////
.SH RETURN VALUE
.\" //////////////////////////////////////////////////////////////////////////
The
.BR seccomp_init ()
function returns a filter context on success, NULL on failure.  The
.BR seccomp_reset ()
function returns zero on success, negative errno values on failure.
.\" //////////////////////////////////////////////////////////////////////////
.SH EXAMPLES
.\" //////////////////////////////////////////////////////////////////////////
.nf
#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;
}
.fi
.\" //////////////////////////////////////////////////////////////////////////
.SH NOTES
.\" //////////////////////////////////////////////////////////////////////////
.P
While the seccomp filter can be generated independent of the kernel, kernel
support is required to load and enforce the seccomp filter generated by
libseccomp.
.P
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 development, please
report any bugs at the project site or directly to the author.
.\" //////////////////////////////////////////////////////////////////////////
.SH AUTHOR
.\" //////////////////////////////////////////////////////////////////////////
Paul Moore <paul@paul-moore.com>
.\" //////////////////////////////////////////////////////////////////////////
.SH SEE ALSO
.\" //////////////////////////////////////////////////////////////////////////
.BR seccomp_release (3)
Commit	Line	Data
8befd5cc MG	1	.TH "seccomp_init" 3 "25 July 2012" "paul@paul-moore.com" "libseccomp Documentation"
	2	.\" //////////////////////////////////////////////////////////////////////////
	3	.SH NAME
	4	.\" //////////////////////////////////////////////////////////////////////////
	5	seccomp_init, seccomp_reset \- Initialize the seccomp filter state
	6	.\" //////////////////////////////////////////////////////////////////////////
	7	.SH SYNOPSIS
	8	.\" //////////////////////////////////////////////////////////////////////////
	9	.nf
	10	.B #include <seccomp.h>
	11	.sp
	12	.B typedef void * scmp_filter_ctx;
	13	.sp
	14	.BI "scmp_filter_ctx seccomp_init(uint32_t " def_action ");"
	15	.BI "int seccomp_reset(scmp_filter_ctx " ctx ", uint32_t " def_action ");"
	16	.sp
	17	Link with \fI\-lseccomp\fP.
	18	.fi
	19	.\" //////////////////////////////////////////////////////////////////////////
	20	.SH DESCRIPTION
	21	.\" //////////////////////////////////////////////////////////////////////////
	22	.P
	23	The
	24	.BR seccomp_init ()
	25	and
	26	.BR seccomp_reset ()
	27	functions (re)initialize the internal seccomp filter state, prepares it for
	28	use, and sets the default action based on the
	29	.I def_action
	30	parameter. The
	31	.BR seccomp_init ()
	32	function must be called before any other libseccomp functions as the rest
	33	of the library API will fail if the filter context is not initialized properly.
	34	The
	35	.BR seccomp_reset ()
	36	function releases the existing filter context state before reinitializing it
	37	and can only be called after a call to
	38	.BR seccomp_init ()
	39	has succeeded.
	40	.P
	41	When the caller is finished configuring the seccomp filter and has loaded it
	42	into the kernel, the caller should call
	43	.BR seccomp_release (3)
	44	to release all of the filter context state.
	45	.P
	46	Valid
	47	.I def_action
	48	values are as follows:
	49	.TP
	50	.B SCMP_ACT_KILL
	51	The thread will be terminated by the kernel with SIGSYS when it calls a syscall
	52	that does not match any of the configured seccomp filter rules. The thread
	53	will not be able to catch the signal.
	54	.TP
	55	.B SCMP_ACT_TRAP
	56	The thread will be sent a SIGSYS signal when it calls a syscall that does not
	57	match any of the configured seccomp filter rules. It may catch this and change
	58	its behavior accordingly. When using SA_SIGINFO with
	59	.BR sigaction (2),
	60	si_code will be set to SYS_SECCOMP, si_syscall will be set to the syscall that
	61	failed the rules, and si_arch will be set to the AUDIT_ARCH for the active ABI.
	62	.TP
	63	.B SCMP_ACT_ERRNO(uint16_t errno)
	64	The thread will receive a return value of
65	.I errno
66	when it calls a syscall that does not match any of the configured seccomp filter
67	rules.
68	.TP
69	.B SCMP_ACT_TRACE(uint16_t msg_num)
70	If the thread is being traced and the tracing process specified the
71	.B PTRACE_O_TRACESECCOMP
72	option in the call to
73	.BR ptrace (2),
74	the tracing process will be notified, via
75	.BR PTRACE_EVENT_SECCOMP ,
76	and the value provided in
77	.I msg_num
78	can be retrieved using the
79	.B PTRACE_GETEVENTMSG
80	option.
81	.TP
82	.B SCMP_ACT_ALLOW
83	The seccomp filter will have no effect on the thread calling the syscall if it
84	does not match any of the configured seccomp filter rules.
85	.\" //////////////////////////////////////////////////////////////////////////
86	.SH RETURN VALUE
87	.\" //////////////////////////////////////////////////////////////////////////
88	The
89	.BR seccomp_init ()
90	function returns a filter context on success, NULL on failure. The
91	.BR seccomp_reset ()
92	function returns zero on success, negative errno values on failure.
93	.\" //////////////////////////////////////////////////////////////////////////
94	.SH EXAMPLES
95	.\" //////////////////////////////////////////////////////////////////////////
96	.nf
97	#include <seccomp.h>
98
99	int main(int argc, char *argv[])
100	{
101	int rc = \-1;
102	scmp_filter_ctx ctx;
103
104	ctx = seccomp_init(SCMP_ACT_KILL);
105	if (ctx == NULL)
106	goto out;
107
108	/* ... */
109
110	rc = seccomp_reset(ctx, SCMP_ACT_KILL);
111	if (rc < 0)
112	goto out;
113
114	/* ... */
115
116	out:
117	seccomp_release(ctx);
118	return \-rc;
119	}
120	.fi
121	.\" //////////////////////////////////////////////////////////////////////////
122	.SH NOTES
123	.\" //////////////////////////////////////////////////////////////////////////
124	.P
125	While the seccomp filter can be generated independent of the kernel, kernel
126	support is required to load and enforce the seccomp filter generated by
127	libseccomp.
128	.P
129	The libseccomp project site, with more information and the source code
130	repository, can be found at https://github.com/seccomp/libseccomp. This tool,
131	as well as the libseccomp library, is currently under development, please
132	report any bugs at the project site or directly to the author.
133	.\" //////////////////////////////////////////////////////////////////////////
134	.SH AUTHOR
135	.\" //////////////////////////////////////////////////////////////////////////
136	Paul Moore <paul@paul-moore.com>
137	.\" //////////////////////////////////////////////////////////////////////////
138	.SH SEE ALSO
139	.\" //////////////////////////////////////////////////////////////////////////
140	.BR seccomp_release (3)
141