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seccomp_merge(3) libseccomp Documentation seccomp_merge(3)

NAME

seccomp_merge - Merge two seccomp filters

SYNOPSIS

#include <seccomp.h>

typedef void * scmp_filter_ctx;

int seccomp_merge(scmp_filter_ctx dst, scmp_filter_ctx src);

Link with -lseccomp.

DESCRIPTION

The seccomp_merge() function merges the seccomp filter in src with the filter in dst and stores the resulting in the dst filter. If successful, the src seccomp filter is released and all internal memory associated with the filter is freed; there is no need to call seccomp_release(3) on src and the caller should discard any references to the filter.

In order to merge two seccomp filters, both filters must have the same attribute values and no overlapping architectures.

RETURN VALUE

Returns zero on success or one of the following error codes on failure:
-EDOM
Unable to merge the filters due to architecture issues, e.g. byte endian mismatches.
-EEXIST
The architecture already exists in the filter.
-EINVAL
One of the filters 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_32, ctx_64;
	ctx_32 = seccomp_init(SCMP_ACT_KILL);
	if (ctx_32 == NULL)
		goto out_all;
	ctx_64 = seccomp_init(SCMP_ACT_KILL);
	if (ctx_64 == NULL)
		goto out_all;
	if (seccomp_arch_exist(ctx_32, SCMP_ARCH_X86) == -EEXIST) {
		rc = seccomp_arch_add(ctx_32, SCMP_ARCH_X86);
		if (rc != 0)
			goto out_all;
		rc = seccomp_arch_remove(ctx_32, SCMP_ARCH_NATIVE);
		if (rc != 0)
			goto out_all;
	}
	if (seccomp_arch_exist(ctx_64, SCMP_ARCH_X86_64) == -EEXIST) {
		rc = seccomp_arch_add(ctx_64, SCMP_ARCH_X86_64);
		if (rc != 0)
			goto out_all;
		rc = seccomp_arch_remove(ctx_64, SCMP_ARCH_NATIVE);
		if (rc != 0)
			goto out_all;
	}
	/* ... */
	rc = seccomp_merge(ctx_64, ctx_32);
	if (rc != 0)
		goto out_all;
	/* NOTE: the 'ctx_32' filter is no longer valid at this point */
	/* ... */
out:
	seccomp_release(ctx_64);
	return -rc;
out_all:
	seccomp_release(ctx_32);
	goto out;
}

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 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.

AUTHOR

Paul Moore <paul@paul-moore.com>

SEE ALSO

seccomp_init(3), seccomp_reset(3), seccomp_arch_add(3), seccomp_arch_remove(3), seccomp_attr_get(3), seccomp_attr_set(3)
30 May 2020 paul@paul-moore.com