drivers: power: report battery voltage in AOSP compatible format

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / seccomp.c

/*
 * linux/kernel/seccomp.c
 *
 * Copyright 2004-2005  Andrea Arcangeli <andrea@cpushare.com>
 *
 * Copyright (C) 2012 Google, Inc.
 * Will Drewry <wad@chromium.org>
 *
 * This defines a simple but solid secure-computing facility.
 *
 * Mode 1 uses a fixed list of allowed system calls.
 * Mode 2 allows user-defined system call filters in the form
 *        of Berkeley Packet Filters/Linux Socket Filters.
 */

#include <linux/atomic.h>
#include <linux/audit.h>
#include <linux/compat.h>
#include <linux/sched.h>
#include <linux/seccomp.h>
#include <linux/slab.h>
#include <linux/syscalls.h>

/* #define SECCOMP_DEBUG 1 */

#ifdef CONFIG_SECCOMP_FILTER
#include <asm/syscall.h>
#include <linux/filter.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
#include <linux/security.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>

/**
 * struct seccomp_filter - container for seccomp BPF programs
 *
 * @usage: reference count to manage the object lifetime.
 *         get/put helpers should be used when accessing an instance
 *         outside of a lifetime-guarded section.  In general, this
 *         is only needed for handling filters shared across tasks.
 * @prev: points to a previously installed, or inherited, filter
 * @len: the number of instructions in the program
 * @insns: the BPF program instructions to evaluate
 *
 * seccomp_filter objects are organized in a tree linked via the @prev
 * pointer.  For any task, it appears to be a singly-linked list starting
 * with current->seccomp.filter, the most recently attached or inherited filter.
 * However, multiple filters may share a @prev node, by way of fork(), which
 * results in a unidirectional tree existing in memory.  This is similar to
 * how namespaces work.
 *
 * seccomp_filter objects should never be modified after being attached
 * to a task_struct (other than @usage).
 */
struct seccomp_filter {
        atomic_t usage;
        struct seccomp_filter *prev;
        unsigned short len;  /* Instruction count */
        struct sock_filter insns[];
};

/* Limit any path through the tree to 256KB worth of instructions. */
#define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))

/**
 * get_u32 - returns a u32 offset into data
 * @data: a unsigned 64 bit value
 * @index: 0 or 1 to return the first or second 32-bits
 *
 * This inline exists to hide the length of unsigned long.  If a 32-bit
 * unsigned long is passed in, it will be extended and the top 32-bits will be
 * 0. If it is a 64-bit unsigned long, then whatever data is resident will be
 * properly returned.
 *
 * Endianness is explicitly ignored and left for BPF program authors to manage
 * as per the specific architecture.
 */
static inline u32 get_u32(u64 data, int index)
{
        return ((u32 *)&data)[index];
}

/* Helper for bpf_load below. */
#define BPF_DATA(_name) offsetof(struct seccomp_data, _name)
/**
 * bpf_load: checks and returns a pointer to the requested offset
 * @off: offset into struct seccomp_data to load from
 *
 * Returns the requested 32-bits of data.
 * seccomp_check_filter() should assure that @off is 32-bit aligned
 * and not out of bounds.  Failure to do so is a BUG.
 */
u32 seccomp_bpf_load(int off)
{
        struct pt_regs *regs = task_pt_regs(current);
        if (off == BPF_DATA(nr))
                return syscall_get_nr(current, regs);
        if (off == BPF_DATA(arch))
                return syscall_get_arch();
        if (off >= BPF_DATA(args[0]) && off < BPF_DATA(args[6])) {
                unsigned long value;
                int arg = (off - BPF_DATA(args[0])) / sizeof(u64);
                int index = !!(off % sizeof(u64));
                syscall_get_arguments(current, regs, arg, 1, &value);
                return get_u32(value, index);
        }
        if (off == BPF_DATA(instruction_pointer))
                return get_u32(KSTK_EIP(current), 0);
        if (off == BPF_DATA(instruction_pointer) + sizeof(u32))
                return get_u32(KSTK_EIP(current), 1);
        /* seccomp_check_filter should make this impossible. */
        BUG();
}

/**
 *      seccomp_check_filter - verify seccomp filter code
 *      @filter: filter to verify
 *      @flen: length of filter
 *
 * Takes a previously checked filter (by sk_chk_filter) and
 * redirects all filter code that loads struct sk_buff data
 * and related data through seccomp_bpf_load.  It also
 * enforces length and alignment checking of those loads.
 *
 * Returns 0 if the rule set is legal or -EINVAL if not.
 */
static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
{
        int pc;
        for (pc = 0; pc < flen; pc++) {
                struct sock_filter *ftest = &filter[pc];
                u16 code = ftest->code;
                u32 k = ftest->k;

                switch (code) {
                case BPF_S_LD_W_ABS:
                        ftest->code = BPF_S_ANC_SECCOMP_LD_W;
                        /* 32-bit aligned and not out of bounds. */
                        if (k >= sizeof(struct seccomp_data) || k & 3)
                                return -EINVAL;
                        continue;
                case BPF_S_LD_W_LEN:
                        ftest->code = BPF_S_LD_IMM;
                        ftest->k = sizeof(struct seccomp_data);
                        continue;
                case BPF_S_LDX_W_LEN:
                        ftest->code = BPF_S_LDX_IMM;
                        ftest->k = sizeof(struct seccomp_data);
                        continue;
                /* Explicitly include allowed calls. */
                case BPF_S_RET_K:
                case BPF_S_RET_A:
                case BPF_S_ALU_ADD_K:
                case BPF_S_ALU_ADD_X:
                case BPF_S_ALU_SUB_K:
                case BPF_S_ALU_SUB_X:
                case BPF_S_ALU_MUL_K:
                case BPF_S_ALU_MUL_X:
                case BPF_S_ALU_DIV_X:
                case BPF_S_ALU_AND_K:
                case BPF_S_ALU_AND_X:
                case BPF_S_ALU_OR_K:
                case BPF_S_ALU_OR_X:
                case BPF_S_ALU_XOR_K:
                case BPF_S_ALU_XOR_X:
                case BPF_S_ALU_LSH_K:
                case BPF_S_ALU_LSH_X:
                case BPF_S_ALU_RSH_K:
                case BPF_S_ALU_RSH_X:
                case BPF_S_ALU_NEG:
                case BPF_S_LD_IMM:
                case BPF_S_LDX_IMM:
                case BPF_S_MISC_TAX:
                case BPF_S_MISC_TXA:
                case BPF_S_ALU_DIV_K:
                case BPF_S_LD_MEM:
                case BPF_S_LDX_MEM:
                case BPF_S_ST:
                case BPF_S_STX:
                case BPF_S_JMP_JA:
                case BPF_S_JMP_JEQ_K:
                case BPF_S_JMP_JEQ_X:
                case BPF_S_JMP_JGE_K:
                case BPF_S_JMP_JGE_X:
                case BPF_S_JMP_JGT_K:
                case BPF_S_JMP_JGT_X:
                case BPF_S_JMP_JSET_K:
                case BPF_S_JMP_JSET_X:
                        continue;
                default:
                        return -EINVAL;
                }
        }
        return 0;
}

/**
 * seccomp_run_filters - evaluates all seccomp filters against @syscall
 * @syscall: number of the current system call
 *
 * Returns valid seccomp BPF response codes.
 */
static u32 seccomp_run_filters(int syscall)
{
        struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
        u32 ret = SECCOMP_RET_ALLOW;

        /* Ensure unexpected behavior doesn't result in failing open. */
        if (unlikely(WARN_ON(f == NULL)))
                return SECCOMP_RET_KILL;

        /* Make sure cross-thread synced filter points somewhere sane. */
        smp_read_barrier_depends();

        /*
         * All filters in the list are evaluated and the lowest BPF return
         * value always takes priority (ignoring the DATA).
         */
        for (; f; f = f->prev) {
                u32 cur_ret = sk_run_filter(NULL, f->insns);
                
                if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
                        ret = cur_ret;
        }
        return ret;
}
#endif /* CONFIG_SECCOMP_FILTER */

static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
{
        assert_spin_locked(&current->sighand->siglock);

        if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
                return false;

        return true;
}

static inline void seccomp_assign_mode(struct task_struct *task,
                                       unsigned long seccomp_mode)
{
        assert_spin_locked(&task->sighand->siglock);

        task->seccomp.mode = seccomp_mode;
        /*
         * Make sure TIF_SECCOMP cannot be set before the mode (and
         * filter) is set.
         */
        smp_mb();
        set_tsk_thread_flag(task, TIF_SECCOMP);
}

#ifdef CONFIG_SECCOMP_FILTER
/* Returns 1 if the parent is an ancestor of the child. */
static int is_ancestor(struct seccomp_filter *parent,
                       struct seccomp_filter *child)
{
        /* NULL is the root ancestor. */
        if (parent == NULL)
                return 1;
        for (; child; child = child->prev)
                if (child == parent)
                        return 1;
        return 0;
}

/**
 * seccomp_can_sync_threads: checks if all threads can be synchronized
 *
 * Expects sighand and cred_guard_mutex locks to be held.
 *
 * Returns 0 on success, -ve on error, or the pid of a thread which was
 * either not in the correct seccomp mode or it did not have an ancestral
 * seccomp filter.
 */
static inline pid_t seccomp_can_sync_threads(void)
{
        struct task_struct *thread, *caller;

        BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
        assert_spin_locked(&current->sighand->siglock);

        /* Validate all threads being eligible for synchronization. */
        caller = current;
        for_each_thread(caller, thread) {
                pid_t failed;

                /* Skip current, since it is initiating the sync. */
                if (thread == caller)
                        continue;

                if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
                    (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
                     is_ancestor(thread->seccomp.filter,
                                 caller->seccomp.filter)))
                        continue;

                /* Return the first thread that cannot be synchronized. */
                failed = task_pid_vnr(thread);
                /* If the pid cannot be resolved, then return -ESRCH */
                if (unlikely(WARN_ON(failed == 0)))
                        failed = -ESRCH;
                return failed;
        }

        return 0;
}

/**
 * seccomp_sync_threads: sets all threads to use current's filter
 *
 * Expects sighand and cred_guard_mutex locks to be held, and for
 * seccomp_can_sync_threads() to have returned success already
 * without dropping the locks.
 *
 */
static inline void seccomp_sync_threads(void)
{
        struct task_struct *thread, *caller;

        BUG_ON(!mutex_is_locked(&current->signal->cred_guard_mutex));
        assert_spin_locked(&current->sighand->siglock);

        /* Synchronize all threads. */
        caller = current;
        for_each_thread(caller, thread) {
                /* Skip current, since it needs no changes. */
                if (thread == caller)
                        continue;

                /* Get a task reference for the new leaf node. */
                get_seccomp_filter(caller);
                /*
                 * Drop the task reference to the shared ancestor since
                 * current's path will hold a reference.  (This also
                 * allows a put before the assignment.)
                 */
                put_seccomp_filter(thread);
                smp_store_release(&thread->seccomp.filter,
                                  caller->seccomp.filter);
                /*
                 * Opt the other thread into seccomp if needed.
                 * As threads are considered to be trust-realm
                 * equivalent (see ptrace_may_access), it is safe to
                 * allow one thread to transition the other.
                 */
                if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) {
                        /*
                         * Don't let an unprivileged task work around
                         * the no_new_privs restriction by creating
                         * a thread that sets it up, enters seccomp,
                         * then dies.
                         */
                        if (task_no_new_privs(caller))
                                task_set_no_new_privs(thread);

                        seccomp_assign_mode(thread, SECCOMP_MODE_FILTER);
                }
        }
}

/**
 * seccomp_prepare_filter: Prepares a seccomp filter for use.
 * @fprog: BPF program to install
 *
 * Returns filter on success or an ERR_PTR on failure.
 */
static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
{
        struct seccomp_filter *filter;
        unsigned long fp_size = fprog->len * sizeof(struct sock_filter);
        unsigned long total_insns = fprog->len;
        long ret;

        if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
                return ERR_PTR(-EINVAL);
        BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));

        for (filter = current->seccomp.filter; filter; filter = filter->prev)
                total_insns += filter->len + 4;  /* include a 4 instr penalty */
        if (total_insns > MAX_INSNS_PER_PATH)
                return ERR_PTR(-ENOMEM);

        /*
         * Installing a seccomp filter requires that the task have
         * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
         * This avoids scenarios where unprivileged tasks can affect the
         * behavior of privileged children.
         */
        if (!task_no_new_privs(current) &&
            security_capable_noaudit(current_cred(), current_user_ns(),
                                     CAP_SYS_ADMIN) != 0)
                return ERR_PTR(-EACCES);

        /* Allocate a new seccomp_filter */
        filter = kzalloc(sizeof(struct seccomp_filter) + fp_size,
                         GFP_KERNEL|__GFP_NOWARN);
        if (!filter)
                return ERR_PTR(-ENOMEM);;
        atomic_set(&filter->usage, 1);
        filter->len = fprog->len;

        /* Copy the instructions from fprog. */
        ret = -EFAULT;
        if (copy_from_user(filter->insns, fprog->filter, fp_size))
                goto fail;

        /* Check and rewrite the fprog via the skb checker */
        ret = sk_chk_filter(filter->insns, filter->len);
        if (ret)
                goto fail;

        /* Check and rewrite the fprog for seccomp use */
        ret = seccomp_check_filter(filter->insns, filter->len);
        if (ret)
                goto fail;

        return filter;

fail:
        kfree(filter);
        return ERR_PTR(ret);
}

/**
 * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
 * @user_filter: pointer to the user data containing a sock_fprog.
 *
 * Returns 0 on success and non-zero otherwise.
 */
static struct seccomp_filter *
seccomp_prepare_user_filter(const char __user *user_filter)
{
        struct sock_fprog fprog;
        struct seccomp_filter *filter = ERR_PTR(-EFAULT);

#ifdef CONFIG_COMPAT
        if (is_compat_task()) {
                struct compat_sock_fprog fprog32;
                if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
                        goto out;
                fprog.len = fprog32.len;
                fprog.filter = compat_ptr(fprog32.filter);
        } else /* falls through to the if below. */
#endif
        if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
                goto out;
        filter = seccomp_prepare_filter(&fprog);
out:
        return filter;
}

/**
 * seccomp_attach_filter: validate and attach filter
 * @flags:  flags to change filter behavior
 * @filter: seccomp filter to add to the current process
 *
 * Caller must be holding current->sighand->siglock lock.
 *
 * Returns 0 on success, -ve on error.
 */
static long seccomp_attach_filter(unsigned int flags,
                                  struct seccomp_filter *filter)
{
        unsigned long total_insns;
        struct seccomp_filter *walker;

        assert_spin_locked(&current->sighand->siglock);

        /* Validate resulting filter length. */
        total_insns = filter->len;
        for (walker = current->seccomp.filter; walker; walker = walker->prev)
                total_insns += walker->len + 4;  /* 4 instr penalty */
        if (total_insns > MAX_INSNS_PER_PATH)
                return -ENOMEM;

        /* If thread sync has been requested, check that it is possible. */
        if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
                int ret;

                ret = seccomp_can_sync_threads();
                if (ret)
                        return ret;
        }

        /*
         * If there is an existing filter, make it the prev and don't drop its
         * task reference.
         */
        filter->prev = current->seccomp.filter;
        current->seccomp.filter = filter;

        /* Now that the new filter is in place, synchronize to all threads. */
        if (flags & SECCOMP_FILTER_FLAG_TSYNC)
                seccomp_sync_threads();

        return 0;
}

/* get_seccomp_filter - increments the reference count of the filter on @tsk */
void get_seccomp_filter(struct task_struct *tsk)
{
        struct seccomp_filter *orig = tsk->seccomp.filter;
        if (!orig)
                return;
        /* Reference count is bounded by the number of total processes. */
        atomic_inc(&orig->usage);
}

static inline void seccomp_filter_free(struct seccomp_filter *filter)
{
        if (filter) {
                kfree(filter);
        }
}

/* put_seccomp_filter - decrements the ref count of tsk->seccomp.filter */
void put_seccomp_filter(struct task_struct *tsk)
{
        struct seccomp_filter *orig = tsk->seccomp.filter;
        /* Clean up single-reference branches iteratively. */
        while (orig && atomic_dec_and_test(&orig->usage)) {
                struct seccomp_filter *freeme = orig;
                orig = orig->prev;
                seccomp_filter_free(freeme);
        }
}

/**
 * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
 * @syscall: syscall number to send to userland
 * @reason: filter-supplied reason code to send to userland (via si_errno)
 *
 * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
 */
static void seccomp_send_sigsys(int syscall, int reason)
{
        struct siginfo info;
        memset(&info, 0, sizeof(info));
        info.si_signo = SIGSYS;
        info.si_code = SYS_SECCOMP;
        info.si_call_addr = (void __user *)KSTK_EIP(current);
        info.si_errno = reason;
        info.si_arch = syscall_get_arch();
        info.si_syscall = syscall;
        force_sig_info(SIGSYS, &info, current);
}
#endif  /* CONFIG_SECCOMP_FILTER */

/*
 * Secure computing mode 1 allows only read/write/exit/sigreturn.
 * To be fully secure this must be combined with rlimit
 * to limit the stack allocations too.
 */
static int mode1_syscalls[] = {
        __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
        0, /* null terminated */
};

#ifdef CONFIG_COMPAT
static int mode1_syscalls_32[] = {
        __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32,
        0, /* null terminated */
};
#endif

int __secure_computing(int this_syscall)
{
        int exit_sig = 0;
        int *syscall;
        u32 ret;

        /*
         * Make sure that any changes to mode from another thread have
         * been seen after TIF_SECCOMP was seen.
         */
        rmb();

        switch (current->seccomp.mode) {
        case SECCOMP_MODE_STRICT:
                syscall = mode1_syscalls;
#ifdef CONFIG_COMPAT
                if (is_compat_task())
                        syscall = mode1_syscalls_32;
#endif
                do {
                        if (*syscall == this_syscall)
                                return 0;
                } while (*++syscall);
                exit_sig = SIGKILL;
                ret = SECCOMP_RET_KILL;
                break;
#ifdef CONFIG_SECCOMP_FILTER
        case SECCOMP_MODE_FILTER: {
                int data;
                struct pt_regs *regs = task_pt_regs(current);
                ret = seccomp_run_filters(this_syscall);
                data = ret & SECCOMP_RET_DATA;
                ret &= SECCOMP_RET_ACTION;
                switch (ret) {
                case SECCOMP_RET_ERRNO:
                        /* Set the low-order 16-bits as a errno. */
                        syscall_set_return_value(current, regs,
                                                 -data, 0);
                        goto skip;
                case SECCOMP_RET_TRAP:
                        /* Show the handler the original registers. */
                        syscall_rollback(current, regs);
                        /* Let the filter pass back 16 bits of data. */
                        seccomp_send_sigsys(this_syscall, data);
                        goto skip;
                case SECCOMP_RET_TRACE:
                        /* Skip these calls if there is no tracer. */
                        if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
                                syscall_set_return_value(current, regs,
                                                         -ENOSYS, 0);
                                goto skip;
                        }
                        /* Allow the BPF to provide the event message */
                        ptrace_event(PTRACE_EVENT_SECCOMP, data);
                        /*
                         * The delivery of a fatal signal during event
                         * notification may silently skip tracer notification.
                         * Terminating the task now avoids executing a system
                         * call that may not be intended.
                         */
                        if (fatal_signal_pending(current))
                                break;
                        if (syscall_get_nr(current, regs) < 0)
                                goto skip;  /* Explicit request to skip. */

                        return 0;
                case SECCOMP_RET_ALLOW:
                        return 0;
                case SECCOMP_RET_KILL:
                default:
                        break;
                }
                exit_sig = SIGSYS;
                break;
        }
#endif
        default:
                BUG();
        }

#ifdef SECCOMP_DEBUG
        dump_stack();
#endif
        audit_seccomp(this_syscall, exit_sig, ret);
        do_exit(exit_sig);
#ifdef CONFIG_SECCOMP_FILTER
skip:
        audit_seccomp(this_syscall, exit_sig, ret);
#endif
        return -1;
}

long prctl_get_seccomp(void)
{
        return current->seccomp.mode;
}

/**
 * seccomp_set_mode_strict: internal function for setting strict seccomp
 *
 * Once current->seccomp.mode is non-zero, it may not be changed.
 *
 * Returns 0 on success or -EINVAL on failure.
 */
static long seccomp_set_mode_strict(void)
{
        const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
        long ret = -EINVAL;

        spin_lock_irq(&current->sighand->siglock);

        if (!seccomp_may_assign_mode(seccomp_mode))
                goto out;

#ifdef TIF_NOTSC
        disable_TSC();
#endif
        seccomp_assign_mode(current, seccomp_mode);
        ret = 0;

out:
        spin_unlock_irq(&current->sighand->siglock);

        return ret;
}

#ifdef CONFIG_SECCOMP_FILTER
/**
 * seccomp_set_mode_filter: internal function for setting seccomp filter
 * @flags:  flags to change filter behavior
 * @filter: struct sock_fprog containing filter
 *
 * This function may be called repeatedly to install additional filters.
 * Every filter successfully installed will be evaluated (in reverse order)
 * for each system call the task makes.
 *
 * Once current->seccomp.mode is non-zero, it may not be changed.
 *
 * Returns 0 on success or -EINVAL on failure.
 */
static long seccomp_set_mode_filter(unsigned int flags,
                                    const char __user *filter)
{
        const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
        struct seccomp_filter *prepared = NULL;
        long ret = -EINVAL;

        /* Validate flags. */
        if (flags & ~SECCOMP_FILTER_FLAG_MASK)
                return -EINVAL;

        /* Prepare the new filter before holding any locks. */
        prepared = seccomp_prepare_user_filter(filter);
        if (IS_ERR(prepared))
                return PTR_ERR(prepared);

        /*
         * Make sure we cannot change seccomp or nnp state via TSYNC
         * while another thread is in the middle of calling exec.
         */
        if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
            mutex_lock_killable(&current->signal->cred_guard_mutex))
                goto out_free;

        spin_lock_irq(&current->sighand->siglock);

        if (!seccomp_may_assign_mode(seccomp_mode))
                goto out;

        ret = seccomp_attach_filter(flags, prepared);
        if (ret)
                goto out;
        /* Do not free the successfully attached filter. */
        prepared = NULL;

        seccomp_assign_mode(current, seccomp_mode);
out:
        spin_unlock_irq(&current->sighand->siglock);
        if (flags & SECCOMP_FILTER_FLAG_TSYNC)
                mutex_unlock(&current->signal->cred_guard_mutex);
out_free:
        seccomp_filter_free(prepared);
        return ret;
}
#else
static inline long seccomp_set_mode_filter(unsigned int flags,
                                           const char __user *filter)
{
        return -EINVAL;
}
#endif

/* Common entry point for both prctl and syscall. */
static long do_seccomp(unsigned int op, unsigned int flags,
                       const char __user *uargs)
{
        switch (op) {
        case SECCOMP_SET_MODE_STRICT:
                if (flags != 0 || uargs != NULL)
                        return -EINVAL;
                return seccomp_set_mode_strict();
        case SECCOMP_SET_MODE_FILTER:
                return seccomp_set_mode_filter(flags, uargs);
        default:
                return -EINVAL;
        }
}

SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
                         const char __user *, uargs)
{
        return do_seccomp(op, flags, uargs);
}

/**
 * prctl_set_seccomp: configures current->seccomp.mode
 * @seccomp_mode: requested mode to use
 * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
 *
 * Returns 0 on success or -EINVAL on failure.
 */
long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
{
        unsigned int op;
        char __user *uargs;

        switch (seccomp_mode) {
        case SECCOMP_MODE_STRICT:
                op = SECCOMP_SET_MODE_STRICT;
                /*
                 * Setting strict mode through prctl always ignored filter,
                 * so make sure it is always NULL here to pass the internal
                 * check in do_seccomp().
                 */
                uargs = NULL;
                break;
        case SECCOMP_MODE_FILTER:
                op = SECCOMP_SET_MODE_FILTER;
                uargs = filter;
                break;
        default:
                return -EINVAL;
        }

        /* prctl interface doesn't have flags, so they are always zero. */
        return do_seccomp(op, 0, uargs);
}