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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLES | NOTES | AUTHOR | SEE ALSO | COLOPHON |
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seccomp_export_bpf(3) libseccomp Documentation seccomp_export_bpf(3)
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);
int seccomp_export_bpf_mem(const scmp_filter_ctx ctx, void *buf, size_t *len);
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.
The seccomp_export_bpf_mem() function is largely the same as
seccomp_export_bpf(), but instead of writing to a file descriptor,
the program will be written to the buf pointer provided by the
caller. The len argument must be initialized with the size of the
buf buffer. If the program was valid, len will be updated with
its size in bytes. If buf was too small to hold the program, len
can be consulted to determine the required size. Passing a NULL
buf may also be used to query the required size ahead of time.
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.
-ERANGE
The provided buffer was too small.
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 <paul@paul-moore.com>
seccomp_init(3), seccomp_release(3)
This page is part of the libseccomp (high-level API to the Linux
Kernel's seccomp filter) project. Information about the project
can be found at ⟨https://github.com/seccomp/libseccomp⟩. If you
have a bug report for this manual page, see
⟨https://groups.google.com/d/forum/libseccomp⟩. This page was
obtained from the project's upstream Git repository
⟨https://github.com/seccomp/libseccomp⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-05-09.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
paul@paul-moore.com 30 May 2020 seccomp_export_bpf(3)
Pages that refer to this page: seccomp(2)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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