--- /dev/null
+/**
+ * Enhanced Seccomp Architecture/Machine Specific Code
+ *
+ * Copyright (c) 2012 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 <elf.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <asm/bitsperlong.h>
+#include <linux/audit.h>
+#include <stdbool.h>
+
+#include <seccomp.h>
+
+#include "arch.h"
+#include "arch-x86.h"
+#include "arch-x86_64.h"
+#include "arch-x32.h"
+#include "arch-arm.h"
+#include "arch-aarch64.h"
+#include "arch-mips.h"
+#include "arch-mips64.h"
+#include "arch-mips64n32.h"
+#include "arch-ppc.h"
+#include "arch-ppc64.h"
+#include "arch-s390.h"
+#include "arch-s390x.h"
+#include "db.h"
+#include "system.h"
+
+#define default_arg_count_max 6
+
+#define default_arg_offset(x) (offsetof(struct seccomp_data, args[x]))
+
+#if __i386__
+const struct arch_def *arch_def_native = &arch_def_x86;
+#elif __x86_64__
+#ifdef __ILP32__
+const struct arch_def *arch_def_native = &arch_def_x32;
+#else
+const struct arch_def *arch_def_native = &arch_def_x86_64;
+#endif /* __ILP32__ */
+#elif __arm__
+const struct arch_def *arch_def_native = &arch_def_arm;
+#elif __aarch64__
+const struct arch_def *arch_def_native = &arch_def_aarch64;
+#elif __mips__ && _MIPS_SIM == _MIPS_SIM_ABI32
+#if __MIPSEB__
+const struct arch_def *arch_def_native = &arch_def_mips;
+#elif __MIPSEL__
+const struct arch_def *arch_def_native = &arch_def_mipsel;
+#endif /* _MIPS_SIM_ABI32 */
+#elif __mips__ && _MIPS_SIM == _MIPS_SIM_ABI64
+#if __MIPSEB__
+const struct arch_def *arch_def_native = &arch_def_mips64;
+#elif __MIPSEL__
+const struct arch_def *arch_def_native = &arch_def_mipsel64;
+#endif /* _MIPS_SIM_ABI64 */
+#elif __mips__ && _MIPS_SIM == _MIPS_SIM_NABI32
+#if __MIPSEB__
+const struct arch_def *arch_def_native = &arch_def_mips64n32;
+#elif __MIPSEL__
+const struct arch_def *arch_def_native = &arch_def_mipsel64n32;
+#endif /* _MIPS_SIM_NABI32 */
+#elif __PPC64__
+#ifdef __BIG_ENDIAN__
+const struct arch_def *arch_def_native = &arch_def_ppc64;
+#else
+const struct arch_def *arch_def_native = &arch_def_ppc64le;
+#endif
+#elif __PPC__
+const struct arch_def *arch_def_native = &arch_def_ppc;
+#elif __s390x__ /* s390x must be checked before s390 */
+const struct arch_def *arch_def_native = &arch_def_s390x;
+#elif __s390__
+const struct arch_def *arch_def_native = &arch_def_s390;
+#else
+#error the arch code needs to know about your machine type
+#endif /* machine type guess */
+
+/**
+ * Validate the architecture token
+ * @param arch the architecture token
+ *
+ * Verify the given architecture token; return zero if valid, -EINVAL if not.
+ *
+ */
+int arch_valid(uint32_t arch)
+{
+ return (arch_def_lookup(arch) ? 0 : -EINVAL);
+}
+
+/**
+ * Lookup the architecture definition
+ * @param token the architecure token
+ *
+ * Return the matching architecture definition, returns NULL on failure.
+ *
+ */
+const struct arch_def *arch_def_lookup(uint32_t token)
+{
+ switch (token) {
+ case SCMP_ARCH_X86:
+ return &arch_def_x86;
+ case SCMP_ARCH_X86_64:
+ return &arch_def_x86_64;
+ case SCMP_ARCH_X32:
+ return &arch_def_x32;
+ case SCMP_ARCH_ARM:
+ return &arch_def_arm;
+ case SCMP_ARCH_AARCH64:
+ return &arch_def_aarch64;
+ case SCMP_ARCH_MIPS:
+ return &arch_def_mips;
+ case SCMP_ARCH_MIPSEL:
+ return &arch_def_mipsel;
+ case SCMP_ARCH_MIPS64:
+ return &arch_def_mips64;
+ case SCMP_ARCH_MIPSEL64:
+ return &arch_def_mipsel64;
+ case SCMP_ARCH_MIPS64N32:
+ return &arch_def_mips64n32;
+ case SCMP_ARCH_MIPSEL64N32:
+ return &arch_def_mipsel64n32;
+ case SCMP_ARCH_PPC:
+ return &arch_def_ppc;
+ case SCMP_ARCH_PPC64:
+ return &arch_def_ppc64;
+ case SCMP_ARCH_PPC64LE:
+ return &arch_def_ppc64le;
+ case SCMP_ARCH_S390:
+ return &arch_def_s390;
+ case SCMP_ARCH_S390X:
+ return &arch_def_s390x;
+ }
+
+ return NULL;
+}
+
+/**
+ * Lookup the architecture definition by name
+ * @param arch_name the architecure name
+ *
+ * Return the matching architecture definition, returns NULL on failure.
+ *
+ */
+const struct arch_def *arch_def_lookup_name(const char *arch_name)
+{
+ if (strcmp(arch_name, "x86") == 0)
+ return &arch_def_x86;
+ else if (strcmp(arch_name, "x86_64") == 0)
+ return &arch_def_x86_64;
+ else if (strcmp(arch_name, "x32") == 0)
+ return &arch_def_x32;
+ else if (strcmp(arch_name, "arm") == 0)
+ return &arch_def_arm;
+ else if (strcmp(arch_name, "aarch64") == 0)
+ return &arch_def_aarch64;
+ else if (strcmp(arch_name, "mips") == 0)
+ return &arch_def_mips;
+ else if (strcmp(arch_name, "mipsel") == 0)
+ return &arch_def_mipsel;
+ else if (strcmp(arch_name, "mips64") == 0)
+ return &arch_def_mips64;
+ else if (strcmp(arch_name, "mipsel64") == 0)
+ return &arch_def_mipsel64;
+ else if (strcmp(arch_name, "mips64n32") == 0)
+ return &arch_def_mips64n32;
+ else if (strcmp(arch_name, "mipsel64n32") == 0)
+ return &arch_def_mipsel64n32;
+ else if (strcmp(arch_name, "ppc") == 0)
+ return &arch_def_ppc;
+ else if (strcmp(arch_name, "ppc64") == 0)
+ return &arch_def_ppc64;
+ else if (strcmp(arch_name, "ppc64le") == 0)
+ return &arch_def_ppc64le;
+ else if (strcmp(arch_name, "s390") == 0)
+ return &arch_def_s390;
+ else if (strcmp(arch_name, "s390x") == 0)
+ return &arch_def_s390x;
+
+ return NULL;
+}
+
+/**
+ * Determine the maximum number of syscall arguments
+ * @param arch the architecture definition
+ *
+ * Determine the maximum number of syscall arguments for the given architecture.
+ * Returns the number of arguments on success, negative values on failure.
+ *
+ */
+int arch_arg_count_max(const struct arch_def *arch)
+{
+ return (arch_valid(arch->token) == 0 ? default_arg_count_max : -EDOM);
+}
+
+/**
+ * Determine the argument offset for the lower 32 bits
+ * @param arch the architecture definition
+ * @param arg the argument number
+ *
+ * Determine the correct offset for the low 32 bits of the given argument based
+ * on the architecture definition. Returns the offset on success, negative
+ * values on failure.
+ *
+ */
+int arch_arg_offset_lo(const struct arch_def *arch, unsigned int arg)
+{
+ if (arch_valid(arch->token) < 0)
+ return -EDOM;
+
+ switch (arch->endian) {
+ case ARCH_ENDIAN_LITTLE:
+ return default_arg_offset(arg);
+ break;
+ case ARCH_ENDIAN_BIG:
+ return default_arg_offset(arg) + 4;
+ break;
+ default:
+ return -EDOM;
+ }
+}
+
+/**
+ * Determine the argument offset for the high 32 bits
+ * @param arch the architecture definition
+ * @param arg the argument number
+ *
+ * Determine the correct offset for the high 32 bits of the given argument
+ * based on the architecture definition. Returns the offset on success,
+ * negative values on failure.
+ *
+ */
+int arch_arg_offset_hi(const struct arch_def *arch, unsigned int arg)
+{
+ if (arch_valid(arch->token) < 0 || arch->size != ARCH_SIZE_64)
+ return -EDOM;
+
+ switch (arch->endian) {
+ case ARCH_ENDIAN_LITTLE:
+ return default_arg_offset(arg) + 4;
+ break;
+ case ARCH_ENDIAN_BIG:
+ return default_arg_offset(arg);
+ break;
+ default:
+ return -EDOM;
+ }
+}
+
+/**
+ * Determine the argument offset
+ * @param arch the architecture definition
+ * @param arg the argument number
+ *
+ * Determine the correct offset for the given argument based on the
+ * architecture definition. Returns the offset on success, negative values on
+ * failure.
+ *
+ */
+int arch_arg_offset(const struct arch_def *arch, unsigned int arg)
+{
+ return arch_arg_offset_lo(arch, arg);
+}
+
+/**
+ * Resolve a syscall name to a number
+ * @param arch the architecture definition
+ * @param name the syscall name
+ *
+ * Resolve the given syscall name to the syscall number based on the given
+ * architecture. Returns the syscall number on success, including negative
+ * pseudo syscall numbers; returns __NR_SCMP_ERROR on failure.
+ *
+ */
+int arch_syscall_resolve_name(const struct arch_def *arch, const char *name)
+{
+ if (arch->syscall_resolve_name)
+ return (*arch->syscall_resolve_name)(name);
+
+ return __NR_SCMP_ERROR;
+}
+
+/**
+ * Resolve a syscall number to a name
+ * @param arch the architecture definition
+ * @param num the syscall number
+ *
+ * Resolve the given syscall number to the syscall name based on the given
+ * architecture. Returns a pointer to the syscall name string on success,
+ * including pseudo syscall names; returns NULL on failure.
+ *
+ */
+const char *arch_syscall_resolve_num(const struct arch_def *arch, int num)
+{
+ if (arch->syscall_resolve_num)
+ return (*arch->syscall_resolve_num)(num);
+
+ return NULL;
+}
+
+/**
+ * Translate the syscall number
+ * @param arch the architecture definition
+ * @param syscall the syscall number
+ *
+ * Translate the syscall number, in the context of the native architecure, to
+ * the provided architecure. Returns zero on success, negative values on
+ * failure.
+ *
+ */
+int arch_syscall_translate(const struct arch_def *arch, int *syscall)
+{
+ int sc_num;
+ const char *sc_name;
+
+ if (arch->token != arch_def_native->token) {
+ sc_name = arch_syscall_resolve_num(arch_def_native, *syscall);
+ if (sc_name == NULL)
+ return -EFAULT;
+
+ sc_num = arch_syscall_resolve_name(arch, sc_name);
+ if (sc_num == __NR_SCMP_ERROR)
+ return -EFAULT;
+
+ *syscall = sc_num;
+ }
+
+ return 0;
+}
+
+/**
+ * Rewrite a syscall value to match the architecture
+ * @param arch the architecture definition
+ * @param syscall the syscall number
+ *
+ * Syscalls can vary across different architectures so this function rewrites
+ * the syscall into the correct value for the specified architecture. Returns
+ * zero on success, -EDOM if the syscall is not defined for @arch, and negative
+ * values on failure.
+ *
+ */
+int arch_syscall_rewrite(const struct arch_def *arch, int *syscall)
+{
+ int sys = *syscall;
+
+ if (sys >= 0) {
+ /* we shouldn't be here - no rewrite needed */
+ return 0;
+ } else if (sys < 0 && sys > -100) {
+ /* reserved values */
+ return -EINVAL;
+ } else if (sys <= -100 && sys > -10000) {
+ /* rewritable syscalls */
+ if (arch->syscall_rewrite)
+ (*arch->syscall_rewrite)(syscall);
+ }
+
+ /* syscalls not defined on this architecture */
+ if ((*syscall) < 0)
+ return -EDOM;
+ return 0;
+}
+
+/**
+ * Add a new rule to the specified filter
+ * @param col the filter collection
+ * @param db the seccomp filter db
+ * @param strict the strict flag
+ * @param action the filter action
+ * @param syscall the syscall number
+ * @param chain_len the number of argument filters in the argument filter chain
+ * @param chain the argument filter chain
+ *
+ * This function adds a new argument/comparison/value to the seccomp filter for
+ * a syscall; multiple arguments can be specified and they will be chained
+ * together (essentially AND'd together) in the filter. When the strict flag
+ * is true the function will fail if the exact rule can not be added to the
+ * filter, if the strict flag is false the function will not fail if the
+ * function needs to adjust the rule due to architecture specifics. Returns
+ * zero on success, negative values on failure.
+ *
+ */
+int arch_filter_rule_add(struct db_filter_col *col, struct db_filter *db,
+ bool strict, uint32_t action, int syscall,
+ unsigned int chain_len, struct db_api_arg *chain)
+{
+ int rc;
+ size_t chain_size = sizeof(*chain) * chain_len;
+ struct db_api_rule_list *rule, *rule_tail;
+
+ /* ensure we aren't using any reserved syscall values */
+ if (syscall < 0 && syscall > -100)
+ return -EINVAL;
+
+ /* translate the syscall */
+ rc = arch_syscall_translate(db->arch, &syscall);
+ if (rc < 0)
+ return rc;
+
+ /* copy of the chain for each filter in the collection */
+ rule = malloc(sizeof(*rule));
+ if (rule == NULL)
+ return -ENOMEM;
+ rule->args = malloc(chain_size);
+ if (rule->args == NULL) {
+ free(rule);
+ return -ENOMEM;
+ }
+ rule->action = action;
+ rule->syscall = syscall;
+ rule->args_cnt = chain_len;
+ memcpy(rule->args, chain, chain_size);
+ rule->prev = NULL;
+ rule->next = NULL;
+
+ /* add the new rule to the existing filter */
+ if (db->arch->rule_add == NULL) {
+ /* negative syscalls require a db->arch->rule_add() function */
+ if (syscall < 0 && strict) {
+ rc = -EDOM;
+ goto rule_add_failure;
+ }
+ rc = db_rule_add(db, rule);
+ } else
+ rc = (db->arch->rule_add)(col, db, strict, rule);
+ if (rc == 0) {
+ /* insert the chain to the end of the filter's rule list */
+ rule_tail = rule;
+ while (rule_tail->next)
+ rule_tail = rule_tail->next;
+ if (db->rules != NULL) {
+ rule->prev = db->rules->prev;
+ rule_tail->next = db->rules;
+ db->rules->prev->next = rule;
+ db->rules->prev = rule_tail;
+ } else {
+ rule->prev = rule_tail;
+ rule_tail->next = rule;
+ db->rules = rule;
+ }
+ } else
+ goto rule_add_failure;
+
+ return 0;
+
+rule_add_failure:
+ do {
+ rule_tail = rule;
+ rule = rule->next;
+ free(rule_tail->args);
+ free(rule_tail);
+ } while (rule);
+ return rc;
+}
projects / linux-seccomp.git / blobdiff