/**
* Seccomp Library API
*
* Copyright (c) 2012,2013 Red Hat <pmoore@redhat.com>
* Author: Paul Moore <paul@paul-moore.com>
*/
/*
* This library is free software; you can redistribute it and/or modify it
* under the terms of version 2.1 of the GNU Lesser General Public License as
* published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, see <http://www.gnu.org/licenses>.
*/
#include <endian.h>
#include <errno.h>
#include <inttypes.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <sys/ioctl.h>
#include <seccomp.h>
#include "arch.h"
#include "db.h"
#include "gen_pfc.h"
#include "gen_bpf.h"
#include "helper.h"
#include "system.h"
#define API __attribute__((visibility("default")))
const struct scmp_version library_version = {
.major = SCMP_VER_MAJOR,
.minor = SCMP_VER_MINOR,
.micro = SCMP_VER_MICRO,
};
unsigned int seccomp_api_level = 0;
/**
* Filter the error codes we send back to callers
* @param err the error code
*
* We consider error codes part of our API so we want to make sure we don't
* accidentally send an undocumented error code to our callers. This function
* helps with that.
*
*/
static int _rc_filter(int err)
{
/* pass through success values */
if (err >= 0)
return err;
/* filter the error codes */
switch (err) {
case -EACCES:
/* NOTE: operation is not permitted by libseccomp */
case -ECANCELED:
/* NOTE: kernel level error that is beyond the control of
* libseccomp */
case -EDOM:
/* NOTE: failure due to arch/ABI */
case -EEXIST:
/* NOTE: operation failed due to existing rule or filter */
case -EINVAL:
/* NOTE: invalid input to the libseccomp API */
case -ENOENT:
/* NOTE: no matching entry found */
case -ENOMEM:
/* NOTE: unable to allocate enough memory to perform the
* requested operation */
case -EOPNOTSUPP:
/* NOTE: operation is not supported */
case -ESRCH:
/* NOTE: operation failed due to multi-threading */
return err;
default:
/* NOTE: this is the default "internal libseccomp error"
* error code, it is our catch-all */
return -EFAULT;
}
}
/**
* Filter the system error codes we send back to callers
* @param col the filter collection
* @param err the error code
*
* This is similar to _rc_filter(), but it first checks the filter attribute
* to determine if we should be filtering the return codes.
*
*/
static int _rc_filter_sys(struct db_filter_col *col, int err)
{
/* pass through success values */
if (err >= 0)
return err;
/* pass the return code if the SCMP_FLTATR_API_SYSRAWRC is true */
if (db_col_attr_read(col, SCMP_FLTATR_API_SYSRAWRC))
return err;
return -ECANCELED;
}
/**
* Validate a filter context
* @param ctx the filter context
*
* Attempt to validate the provided filter context. Returns zero if the
* context is valid, negative values on failure.
*
*/
static int _ctx_valid(const scmp_filter_ctx *ctx)
{
return db_col_valid((struct db_filter_col *)ctx);
}
/**
* Validate a syscall number
* @param syscall the syscall number
*
* Attempt to perform basic syscall number validation. Returns zero of the
* syscall appears valid, negative values on failure.
*
*/
static int _syscall_valid(const struct db_filter_col *col, int syscall)
{
/* syscall -1 is used by tracers to skip the syscall */
if (col->attr.api_tskip && syscall == -1)
return 0;
if (syscall <= -1 && syscall >= -99)
return -EINVAL;
return 0;
}
/**
* Update the API level
*
* This function performs a series of tests to determine what functionality is
* supported given the current running environment (kernel, etc.). It is
* important to note that this function only does meaningful checks the first
* time it is run, the resulting API level is cached after this first run and
* used for all subsequent calls. The API level value is returned.
*
*/
static unsigned int _seccomp_api_update(void)
{
unsigned int level = 1;
/* if seccomp_api_level > 0 then it's already been set, we're done */
if (seccomp_api_level >= 1)
return seccomp_api_level;
/* NOTE: level 1 is the base level, start checking at 2 */
if (sys_chk_seccomp_syscall() &&
sys_chk_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC) == 1)
level = 2;
if (level == 2 &&
sys_chk_seccomp_flag(SECCOMP_FILTER_FLAG_LOG) == 1 &&
sys_chk_seccomp_action(SCMP_ACT_LOG) == 1 &&
sys_chk_seccomp_action(SCMP_ACT_KILL_PROCESS) == 1)
level = 3;
if (level == 3 &&
sys_chk_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 1)
level = 4;
if (level == 4 &&
sys_chk_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER) == 1 &&
sys_chk_seccomp_action(SCMP_ACT_NOTIFY) == 1)
level = 5;
if (level == 5 &&
sys_chk_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 1)
level = 6;
/* update the stored api level and return */
seccomp_api_level = level;
return seccomp_api_level;
}
/* NOTE - function header comment in include/seccomp.h */
API const struct scmp_version *seccomp_version(void)
{
return &library_version;
}
/* NOTE - function header comment in include/seccomp.h */
API unsigned int seccomp_api_get(void)
{
/* update the api level, if needed */
return _seccomp_api_update();
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_api_set(unsigned int level)
{
switch (level) {
case 1:
sys_set_seccomp_syscall(false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_LOG, false);
sys_set_seccomp_action(SCMP_ACT_LOG, false);
sys_set_seccomp_action(SCMP_ACT_KILL_PROCESS, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER, false);
sys_set_seccomp_action(SCMP_ACT_NOTIFY, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH, false);
break;
case 2:
sys_set_seccomp_syscall(true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_LOG, false);
sys_set_seccomp_action(SCMP_ACT_LOG, false);
sys_set_seccomp_action(SCMP_ACT_KILL_PROCESS, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER, false);
sys_set_seccomp_action(SCMP_ACT_NOTIFY, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH, false);
break;
case 3:
sys_set_seccomp_syscall(true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_LOG, true);
sys_set_seccomp_action(SCMP_ACT_LOG, true);
sys_set_seccomp_action(SCMP_ACT_KILL_PROCESS, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER, false);
sys_set_seccomp_action(SCMP_ACT_NOTIFY, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH, false);
break;
case 4:
sys_set_seccomp_syscall(true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_LOG, true);
sys_set_seccomp_action(SCMP_ACT_LOG, true);
sys_set_seccomp_action(SCMP_ACT_KILL_PROCESS, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER, false);
sys_set_seccomp_action(SCMP_ACT_NOTIFY, false);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH, false);
break;
case 5:
sys_set_seccomp_syscall(true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_LOG, true);
sys_set_seccomp_action(SCMP_ACT_LOG, true);
sys_set_seccomp_action(SCMP_ACT_KILL_PROCESS, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER, true);
sys_set_seccomp_action(SCMP_ACT_NOTIFY, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH, false);
break;
case 6:
sys_set_seccomp_syscall(true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_LOG, true);
sys_set_seccomp_action(SCMP_ACT_LOG, true);
sys_set_seccomp_action(SCMP_ACT_KILL_PROCESS, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_SPEC_ALLOW, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_NEW_LISTENER, true);
sys_set_seccomp_action(SCMP_ACT_NOTIFY, true);
sys_set_seccomp_flag(SECCOMP_FILTER_FLAG_TSYNC_ESRCH, true);
break;
default:
return _rc_filter(-EINVAL);
}
seccomp_api_level = level;
return _rc_filter(0);
}
/* NOTE - function header comment in include/seccomp.h */
API scmp_filter_ctx seccomp_init(uint32_t def_action)
{
/* force a runtime api level detection */
_seccomp_api_update();
if (db_col_action_valid(NULL, def_action) < 0)
return NULL;
return db_col_init(def_action);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_reset(scmp_filter_ctx ctx, uint32_t def_action)
{
struct db_filter_col *col = (struct db_filter_col *)ctx;
/* a NULL filter context indicates we are resetting the global state */
if (ctx == NULL) {
/* reset the global state and redetermine the api level */
sys_reset_state();
_seccomp_api_update();
return _rc_filter(0);
}
/* ensure the default action is valid */
if (db_col_action_valid(NULL, def_action) < 0)
return _rc_filter(-EINVAL);
/* reset the filter */
return _rc_filter(db_col_reset(col, def_action));
}
/* NOTE - function header comment in include/seccomp.h */
API void seccomp_release(scmp_filter_ctx ctx)
{
db_col_release((struct db_filter_col *)ctx);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_merge(scmp_filter_ctx ctx_dst, scmp_filter_ctx ctx_src)
{
struct db_filter_col *col_dst = (struct db_filter_col *)ctx_dst;
struct db_filter_col *col_src = (struct db_filter_col *)ctx_src;
if (db_col_valid(col_dst) || db_col_valid(col_src))
return _rc_filter(-EINVAL);
/* NOTE: only the default action, NNP, and TSYNC settings must match */
if ((col_dst->attr.act_default != col_src->attr.act_default) ||
(col_dst->attr.nnp_enable != col_src->attr.nnp_enable) ||
(col_dst->attr.tsync_enable != col_src->attr.tsync_enable))
return _rc_filter(-EINVAL);
return _rc_filter(db_col_merge(col_dst, col_src));
}
/* NOTE - function header comment in include/seccomp.h */
API uint32_t seccomp_arch_resolve_name(const char *arch_name)
{
const struct arch_def *arch;
if (arch_name == NULL)
return 0;
arch = arch_def_lookup_name(arch_name);
if (arch == NULL)
return 0;
return arch->token;
}
/* NOTE - function header comment in include/seccomp.h */
API uint32_t seccomp_arch_native(void)
{
return arch_def_native->token;
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_arch_exist(const scmp_filter_ctx ctx, uint32_t arch_token)
{
struct db_filter_col *col = (struct db_filter_col *)ctx;
if (arch_token == 0)
arch_token = arch_def_native->token;
if (arch_valid(arch_token))
return _rc_filter(-EINVAL);
return _rc_filter((db_col_arch_exist(col, arch_token) ? 0 : -EEXIST));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_arch_add(scmp_filter_ctx ctx, uint32_t arch_token)
{
const struct arch_def *arch;
struct db_filter_col *col = (struct db_filter_col *)ctx;
if (arch_token == 0)
arch_token = arch_def_native->token;
arch = arch_def_lookup(arch_token);
if (arch == NULL)
return _rc_filter(-EINVAL);
if (db_col_arch_exist(col, arch_token))
return _rc_filter(-EEXIST);
return _rc_filter(db_col_db_new(col, arch));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_arch_remove(scmp_filter_ctx ctx, uint32_t arch_token)
{
struct db_filter_col *col = (struct db_filter_col *)ctx;
if (arch_token == 0)
arch_token = arch_def_native->token;
if (arch_valid(arch_token))
return _rc_filter(-EINVAL);
if (db_col_arch_exist(col, arch_token) != -EEXIST)
return _rc_filter(-EEXIST);
return _rc_filter(db_col_db_remove(col, arch_token));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_load(const scmp_filter_ctx ctx)
{
struct db_filter_col *col;
bool rawrc;
if (_ctx_valid(ctx))
return _rc_filter(-EINVAL);
col = (struct db_filter_col *)ctx;
rawrc = db_col_attr_read(col, SCMP_FLTATR_API_SYSRAWRC);
return _rc_filter(sys_filter_load(col, rawrc));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_attr_get(const scmp_filter_ctx ctx,
enum scmp_filter_attr attr, uint32_t *value)
{
if (_ctx_valid(ctx))
return _rc_filter(-EINVAL);
return _rc_filter(db_col_attr_get((const struct db_filter_col *)ctx,
attr, value));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_attr_set(scmp_filter_ctx ctx,
enum scmp_filter_attr attr, uint32_t value)
{
if (_ctx_valid(ctx))
return _rc_filter(-EINVAL);
return _rc_filter(db_col_attr_set((struct db_filter_col *)ctx,
attr, value));
}
/* NOTE - function header comment in include/seccomp.h */
API char *seccomp_syscall_resolve_num_arch(uint32_t arch_token, int num)
{
const struct arch_def *arch;
const char *name;
if (arch_token == 0)
arch_token = arch_def_native->token;
if (arch_valid(arch_token))
return NULL;
arch = arch_def_lookup(arch_token);
if (arch == NULL)
return NULL;
name = arch_syscall_resolve_num(arch, num);
if (name == NULL)
return NULL;
return strdup(name);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_syscall_resolve_name_arch(uint32_t arch_token, const char *name)
{
const struct arch_def *arch;
if (name == NULL)
return __NR_SCMP_ERROR;
if (arch_token == 0)
arch_token = arch_def_native->token;
if (arch_valid(arch_token))
return __NR_SCMP_ERROR;
arch = arch_def_lookup(arch_token);
if (arch == NULL)
return __NR_SCMP_ERROR;
return arch_syscall_resolve_name(arch, name);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_syscall_resolve_name_rewrite(uint32_t arch_token,
const char *name)
{
int rc;
int syscall;
const struct arch_def *arch;
if (name == NULL)
return __NR_SCMP_ERROR;
if (arch_token == 0)
arch_token = arch_def_native->token;
if (arch_valid(arch_token))
return __NR_SCMP_ERROR;
arch = arch_def_lookup(arch_token);
if (arch == NULL)
return __NR_SCMP_ERROR;
syscall = arch_syscall_resolve_name(arch, name);
if (syscall == __NR_SCMP_ERROR)
return __NR_SCMP_ERROR;
rc = arch_syscall_rewrite(arch, &syscall);
if (rc == -EDOM)
/* if we can't rewrite the syscall, just pass it through */
return syscall;
else if (rc < 0)
return __NR_SCMP_ERROR;
return syscall;
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_syscall_resolve_name(const char *name)
{
return seccomp_syscall_resolve_name_arch(SCMP_ARCH_NATIVE, name);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_syscall_priority(scmp_filter_ctx ctx,
int syscall, uint8_t priority)
{
struct db_filter_col *col = (struct db_filter_col *)ctx;
if (db_col_valid(col) || _syscall_valid(col, syscall))
return _rc_filter(-EINVAL);
return _rc_filter(db_col_syscall_priority(col, syscall, priority));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_rule_add_array(scmp_filter_ctx ctx,
uint32_t action, int syscall,
unsigned int arg_cnt,
const struct scmp_arg_cmp *arg_array)
{
int rc;
struct db_filter_col *col = (struct db_filter_col *)ctx;
if (arg_cnt > ARG_COUNT_MAX)
return _rc_filter(-EINVAL);
if (arg_cnt > 0 && arg_array == NULL)
return _rc_filter(-EINVAL);
if (db_col_valid(col) || _syscall_valid(col, syscall))
return _rc_filter(-EINVAL);
rc = db_col_action_valid(col, action);
if (rc < 0)
return _rc_filter(rc);
if (action == col->attr.act_default)
return _rc_filter(-EACCES);
return _rc_filter(db_col_rule_add(col, 0, action,
syscall, arg_cnt, arg_array));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_rule_add(scmp_filter_ctx ctx,
uint32_t action, int syscall,
unsigned int arg_cnt, ...)
{
int rc;
int iter;
struct scmp_arg_cmp arg_array[ARG_COUNT_MAX];
va_list arg_list;
/* arg_cnt is unsigned, so no need to check the lower bound */
if (arg_cnt > ARG_COUNT_MAX)
return _rc_filter(-EINVAL);
va_start(arg_list, arg_cnt);
for (iter = 0; iter < arg_cnt; ++iter)
arg_array[iter] = va_arg(arg_list, struct scmp_arg_cmp);
rc = seccomp_rule_add_array(ctx, action, syscall, arg_cnt, arg_array);
va_end(arg_list);
return _rc_filter(rc);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_rule_add_exact_array(scmp_filter_ctx ctx,
uint32_t action, int syscall,
unsigned int arg_cnt,
const struct scmp_arg_cmp *arg_array)
{
int rc;
struct db_filter_col *col = (struct db_filter_col *)ctx;
if (arg_cnt > ARG_COUNT_MAX)
return _rc_filter(-EINVAL);
if (arg_cnt > 0 && arg_array == NULL)
return _rc_filter(-EINVAL);
if (db_col_valid(col) || _syscall_valid(col, syscall))
return _rc_filter(-EINVAL);
rc = db_col_action_valid(col, action);
if (rc < 0)
return _rc_filter(rc);
if (action == col->attr.act_default)
return _rc_filter(-EACCES);
if (col->filter_cnt > 1)
return _rc_filter(-EOPNOTSUPP);
return _rc_filter(db_col_rule_add(col, 1, action,
syscall, arg_cnt, arg_array));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_rule_add_exact(scmp_filter_ctx ctx,
uint32_t action, int syscall,
unsigned int arg_cnt, ...)
{
int rc;
int iter;
struct scmp_arg_cmp arg_array[ARG_COUNT_MAX];
va_list arg_list;
/* arg_cnt is unsigned, so no need to check the lower bound */
if (arg_cnt > ARG_COUNT_MAX)
return _rc_filter(-EINVAL);
va_start(arg_list, arg_cnt);
for (iter = 0; iter < arg_cnt; ++iter)
arg_array[iter] = va_arg(arg_list, struct scmp_arg_cmp);
rc = seccomp_rule_add_exact_array(ctx,
action, syscall, arg_cnt, arg_array);
va_end(arg_list);
return _rc_filter(rc);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_notify_alloc(struct seccomp_notif **req,
struct seccomp_notif_resp **resp)
{
/* force a runtime api level detection */
_seccomp_api_update();
return _rc_filter(sys_notify_alloc(req, resp));
}
/* NOTE - function header comment in include/seccomp.h */
API void seccomp_notify_free(struct seccomp_notif *req,
struct seccomp_notif_resp *resp)
{
if (req)
free(req);
if (resp)
free(resp);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_notify_receive(int fd, struct seccomp_notif *req)
{
return _rc_filter(sys_notify_receive(fd, req));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_notify_respond(int fd, struct seccomp_notif_resp *resp)
{
return _rc_filter(sys_notify_respond(fd, resp));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_notify_id_valid(int fd, uint64_t id)
{
/* force a runtime api level detection */
_seccomp_api_update();
return _rc_filter(sys_notify_id_valid(fd, id));
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_notify_fd(const scmp_filter_ctx ctx)
{
/* NOTE: for historical reasons, and possibly future use, we require a
* valid filter context even though we don't actual use it here; the
* api update is also not strictly necessary, but keep it for now */
/* force a runtime api level detection */
_seccomp_api_update();
if (_ctx_valid(ctx))
return _rc_filter(-EINVAL);
return _rc_filter(sys_notify_fd());
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_export_pfc(const scmp_filter_ctx ctx, int fd)
{
int rc;
struct db_filter_col *col;
if (_ctx_valid(ctx))
return _rc_filter(-EINVAL);
col = (struct db_filter_col *)ctx;
rc = gen_pfc_generate(col, fd);
return _rc_filter_sys(col, rc);
}
/* NOTE - function header comment in include/seccomp.h */
API int seccomp_export_bpf(const scmp_filter_ctx ctx, int fd)
{
int rc;
struct db_filter_col *col;
struct bpf_program *program;
if (_ctx_valid(ctx))
return _rc_filter(-EINVAL);
col = (struct db_filter_col *)ctx;
rc = gen_bpf_generate(col, &program);
if (rc < 0)
return _rc_filter(rc);
rc = write(fd, program->blks, BPF_PGM_SIZE(program));
gen_bpf_release(program);
if (rc < 0)
return _rc_filter_sys(col, -errno);
return 0;
}