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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLES | NOTES | AUTHOR | SEE ALSO | COLOPHON |
seccomp_attr_set(3) libseccomp Documentation seccomp_attr_set(3)
seccomp_attr_set, seccomp_attr_get - Manage the seccomp filter
attributes
#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.
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.
Setting this to off ( value == 0) results in no action,
meaning that loading the seccomp filter into the kernel will
fail if CAP_SYS_ADMIN is missing and NO_NEW_PRIVS has not been
externally 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).
SCMP_FLTATR_API_TSKIP
A flag to specify if libseccomp should allow filter rules to
be created for the -1 syscall. The -1 syscall value can be
used by tracer programs to skip specific syscall invocations,
see seccomp(2) for more information. Defaults to off ( value
== 0).
SCMP_FLTATR_CTL_LOG
A flag to specify if the kernel should log all filter actions
taken except for the SCMP_ACT_ALLOW action. Defaults to off (
value == 0).
SCMP_FLTATR_CTL_SSB
A flag to disable Speculative Store Bypass mitigations for
this filter. Defaults to off ( value == 0).
SCMP_FLTATR_CTL_OPTIMIZE
A flag to specify the optimization level of the seccomp
filter. By default libseccomp generates a set of sequential
´if´ statements for each rule in the filter.
seccomp_syscall_priority(3) can be used to prioritize the
order for the default cause. The binary tree optimization
sorts by syscall numbers and generates consistent O(log n)
filter traversal for every rule in the filter. The binary
tree may be advantageous for large filters. Note that
seccomp_syscall_priority(3) is ignored when
SCMP_FLTATR_CTL_OPTIMIZE == 2.
The different optimization levels are described below:
0 Reserved value, not currently used.
1 Rules sorted by priority and complexity (DEFAULT).
2 Binary tree sorted by syscall number.
SCMP_FLTATR_API_SYSRAWRC
A flag to specify if libseccomp should pass system error codes
back to the caller instead of the default -ECANCELED.
Defaults to off ( value == 0).
Returns zero on success or one of the following error codes on
failure:
-EACCES
Setting the attribute with the given value is not allowed.
-EEXIST
The attribute does not exist.
-EINVAL
Invalid input, either the context or architecture token is
invalid.
-EOPNOTSUPP
The library doesn't support the particular operation.
#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;
}
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_reset(3), seccomp_load(3), seccomp(2)
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 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-04.) 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 06 June 2020 seccomp_attr_set(3)
Pages that refer to this page: seccomp_merge(3) , seccomp_rule_add(3) , seccomp_rule_add_array(3) , seccomp_rule_add_exact(3) , seccomp_rule_add_exact_array(3)