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 internal 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 properly.
The
seccomp_reset() function releases the existing filter context state
before reinitializing it and can only be called after a call to
seccomp_init() has succeeded.
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 process will be killed by the kernel when it calls a syscall that does
not match any of the configured seccomp filter rules.
- SCMP_ACT_TRAP
- The process will throw a SIGSYS signal when it calls a syscall that does
not match any of the configured seccomp filter rules.
- SCMP_ACT_ERRNO(uint16_t errno)
- The process 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 process 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_ALLOW
- The seccomp filter will have no effect on the process calling the syscall
if it does not match any of the configured seccomp filter rules.
RETURN VALUE¶
The
seccomp_init() function returns a filter context on success, NULL on
failure. The
seccomp_reset() function returns zero on success, negative
errno values on failure.
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 generated by
libseccomp.
The libseccomp project site, with more information and the source code
repository, can be found at
http://libseccomp.sf.net. This library is
currently under development, 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)