seccomp_export_bpf, seccomp_export_pfc - Export the seccomp filter
#include <seccomp.h>
typedef void * scmp_filter_ctx;
int seccomp_export_bpf(const scmp_filter_ctx ctx, int fd);
int seccomp_export_pfc(const scmp_filter_ctx ctx, int fd);
Link with -lseccomp.
The
seccomp_export_bpf() and
seccomp_export_pfc() functions
generate and output the current seccomp filter in either BPF (Berkeley Packet
Filter) or PFC (Pseudo Filter Code). The output of
seccomp_export_bpf()
is suitable for loading into the kernel, while the output of
seccomp_export_pfc() is human readable and is intended primarily as a
debugging tool for developers using libseccomp. Both functions write the
filter to the
fd file descriptor.
The filter context
ctx is the value returned by the call to
seccomp_init(3).
While the two output formats are guaranteed to be functionally equivalent for
the given seccomp filter configuration, the filter instructions, and their
ordering, are not guaranteed to be the same in both the BPF and PFC formats.
Return zero on success or one of the following error codes on failure:
- -ECANCELED
- There was a system failure beyond the control of the
library.
- -EFAULT
- Internal libseccomp failure.
- -EINVAL
- Invalid input, either the context or architecture token is
invalid.
- -ENOMEM
- The library was unable to allocate enough memory.
If the
SCMP_FLTATR_API_SYSRAWRC filter attribute is non-zero then
additional error codes may be returned to the caller; these additional error
codes are the negative
errno values returned by the system.
Unfortunately libseccomp can make no guarantees about these return values.
#include <seccomp.h>
int main(int argc, char *argv[])
{
int rc = -1;
scmp_filter_ctx ctx;
int filter_fd;
ctx = seccomp_init(SCMP_ACT_KILL);
if (ctx == NULL)
goto out;
/* ... */
filter_fd = open("/tmp/seccomp_filter.bpf", O_WRONLY);
if (filter_fd == -1) {
rc = -errno;
goto out;
}
rc = seccomp_export_bpf(ctx, filter_fd);
if (rc < 0) {
close(filter_fd);
goto out;
}
close(filter_fd);
/* ... */
out:
seccomp_release(ctx);
return -rc;
}
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
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.
Paul Moore <
[email protected]>
seccomp_init(3),
seccomp_release(3)