NAME¶
seccomp_attr_set, seccomp_attr_get - Manage the seccomp filter attributes
SYNOPSIS¶
#include <seccomp.h>
typedef void * scmp_filter_ctx;
enum scmp_filter_attr;
int seccomp_attr_set(scmp_filter_ctx ctx,
enum scmp_filter_attr attr, uint32_t value);
int seccomp_attr_get(scmp_filter_ctx ctx,
enum scmp_filter_attr attr, uint32_t *value);
Link with -lseccomp.
DESCRIPTION¶
The
seccomp_attr_set() function sets the different seccomp filter
attributes while the
seccomp_attr_get() function fetches the filter
attributes. The seccomp filter attributes are tunable values that affect how
the library behaves when generating and loading the seccomp filter into the
kernel. The attributes are reset to their default values whenever the filter
is initialized or reset via
seccomp_filter_init(3) or
seccomp_filter_reset(3).
The filter context
ctx is the value returned by the call to
seccomp_init(3).
Valid
attr values are as follows:
- SCMP_FLTATR_ACT_DEFAULT
- The default filter action as specified in the call to
seccomp_filter_init(3) or seccomp_filter_reset(3). This
attribute is read-only.
- SCMP_FLTATR_ACT_BADARCH
- The filter action taken when the loaded filter does not match the
architecture of the executing application. Defaults to the
SCMP_ACT_KILL action.
- SCMP_FLTATR_CTL_NNP
- A flag to specify if the NO_NEW_PRIVS functionality should be enabled
before loading the seccomp filter into the kernel. If set to off (
value == 0) then loading the seccomp filter into the kernel will
fail if CAP_SYS_ADMIN is not set. Defaults to on ( value ==
1).
- SCMP_FLTATR_CTL_TSYNC
- A flag to specify if the kernel should attempt to synchronize the filters
across all threads on seccomp_load(3). If the kernel is unable to
synchronize all of the thread then the load operation will fail. This flag
is only available on Linux Kernel 3.17 or greater; attempting to enable
this flag on earlier kernels will result in an error being returned.
Defaults to off ( value == 0).
RETURN VALUE¶
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_ALLOW);
if (ctx == NULL)
goto out;
/* ... */
rc = seccomp_attr_set(ctx, SCMP_FLTATR_ACT_BADARCH, SCMP_ACT_TRAP);
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
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_load(3)