# seccomp_attr_set

## 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_init(3) or seccomp_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_init(3) or seccomp_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).
    
           **SCMP_FLTATR_CTL_WAITKILL**
                  A flag to specify if libseccomp should request wait
                  killable semantics when possible.  Defaults to off (_value_
                  == 0).
    


## RETURN VALUE



           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.
    


## 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.
    


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