Bundle libseccomp 2.3.1

[linux-seccomp.git] / libseccomp / doc / man / man3 / seccomp_attr_set.3

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+.TH "seccomp_attr_set" 3 "21 August 2014" "paul@paul-moore.com" "libseccomp Documentation"
+.\" //////////////////////////////////////////////////////////////////////////
+.SH NAME
+.\" //////////////////////////////////////////////////////////////////////////
+seccomp_attr_set, seccomp_attr_get \- Manage the seccomp filter attributes
+.\" //////////////////////////////////////////////////////////////////////////
+.SH SYNOPSIS
+.\" //////////////////////////////////////////////////////////////////////////
+.nf
+.B #include <seccomp.h>
+.sp
+.B typedef void * scmp_filter_ctx;
+.B enum scmp_filter_attr;
+.sp
+.BI "int seccomp_attr_set(scmp_filter_ctx " ctx ","
+.BI "                     enum scmp_filter_attr " attr ", uint32_t " value ");"
+.BI "int seccomp_attr_get(scmp_filter_ctx " ctx ","
+.BI "                     enum scmp_filter_attr " attr ", uint32_t *" value ");"
+.sp
+Link with \fI\-lseccomp\fP.
+.fi
+.\" //////////////////////////////////////////////////////////////////////////
+.SH DESCRIPTION
+.\" //////////////////////////////////////////////////////////////////////////
+.P
+The
+.BR seccomp_attr_set ()
+function sets the different seccomp filter attributes while the
+.BR 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
+.BR seccomp_filter_init (3)
+or
+.BR seccomp_filter_reset (3).
+.P
+The filter context
+.I ctx
+is the value returned by the call to
+.BR seccomp_init (3).
+.P
+Valid
+.I attr
+values are as follows:
+.TP
+.B SCMP_FLTATR_ACT_DEFAULT
+The default filter action as specified in the call to
+.BR seccomp_filter_init (3)
+or
+.BR seccomp_filter_reset (3).
+This attribute is read-only.
+.TP
+.B SCMP_FLTATR_ACT_BADARCH
+The filter action taken when the loaded filter does not match the architecture
+of the executing application.  Defaults to the
+.B SCMP_ACT_KILL
+action.
+.TP
+.B 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 (
+.I value
+== 0) then loading the seccomp filter into the kernel will fail if CAP_SYS_ADMIN
+is not set.  Defaults to on (
+.I value
+== 1).
+.TP
+.B SCMP_FLTATR_CTL_TSYNC
+A flag to specify if the kernel should attempt to synchronize the filters
+across all threads on
+.BR 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 (
+.I value
+== 0).
+.\" //////////////////////////////////////////////////////////////////////////
+.SH RETURN VALUE
+.\" //////////////////////////////////////////////////////////////////////////
+Returns zero on success, negative errno values on failure.
+.\" //////////////////////////////////////////////////////////////////////////
+.SH EXAMPLES
+.\" //////////////////////////////////////////////////////////////////////////
+.nf
+#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;
+}
+.fi
+.\" //////////////////////////////////////////////////////////////////////////
+.SH NOTES
+.\" //////////////////////////////////////////////////////////////////////////
+.P
+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.
+.P
+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.
+.\" //////////////////////////////////////////////////////////////////////////
+.SH AUTHOR
+.\" //////////////////////////////////////////////////////////////////////////
+Paul Moore <paul@paul-moore.com>
+.\" //////////////////////////////////////////////////////////////////////////
+.SH SEE ALSO
+.\" //////////////////////////////////////////////////////////////////////////
+.BR seccomp_init (3),
+.BR seccomp_reset (3),
+.BR seccomp_load (3)