aboutsummaryrefslogtreecommitdiffstats
path: root/arch/microblaze/include
Commit message (Expand)AuthorAge
* ns: Wire up the setns system callEric W. Biederman2011-05-28
* Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6Linus Torvalds2011-04-07
|\
| * Fix common misspellingsLucas De Marchi2011-03-31
* | microblaze: Wire up new syscallsMichal Simek2011-04-01
|/
* Merge branch 'next' of git://git.monstr.eu/linux-2.6-microblazeLinus Torvalds2011-03-16
|\
| * microblaze: Fix circular headers dependency when ftrace is enabled.Michal Simek2011-03-10
| * microblaze: Fix /dev/zero corruption from __clear_user()Steven J. Magnani2011-03-09
| * microblaze: Fix sparse warning - fault.cMichal Simek2011-03-09
| * microblaze: Fix missing microblaze specific syscalls declarationMichal Simek2011-03-09
| * microblaze: Fix sparse warning - cpuinfo.hMichal Simek2011-03-09
| * microblaze: Fix sparse warning - consistent_alloc functionMichal Simek2011-03-09
| * microblaze: Fix sparse warnings - ptraceMichal Simek2011-03-09
| * microblaze: Fix sparse warning - sw_exceptionsMichal Simek2011-03-09
| * microblaze: trivial: Add one empty lineMichal Simek2011-03-09
| * microblaze: Fix coding style - ptrace.hMichal Simek2011-03-09
| * microblaze: Fix GDB issue caused by cache issueMichal Simek2011-03-09
| * microblaze: Remove r0_ram pointer and PTO alignmentMichal Simek2011-03-09
| * microblaze: Fix unaligned.h for endiansMichal Simek2011-03-09
* | Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/k...Linus Torvalds2011-03-15
|\ \
| * | Merge branch 'linus' into x86/platformThomas Gleixner2011-02-23
| |\|
| * | of/pci: move of_irq_map_pci() into generic codeSebastian Andrzej Siewior2011-02-04
* | | futex: Sanitize futex ops argument typesMichel Lespinasse2011-03-11
* | | futex: Sanitize cmpxchg_futex_value_locked APIMichel Lespinasse2011-03-11
| |/ |/|
* | microblaze: Fix pte_update functionMichal Simek2011-02-07
* | microblaze: Fix IRQ flag handling for MSR=0Michal Simek2011-02-07
|/
* microblaze: Fix asm/pgtable.hMichal Simek2011-01-16
* microblaze: Fix missing pagemap.hMichal Simek2011-01-16
* Merge branch 'next' of git://git.monstr.eu/linux-2.6-microblazeLinus Torvalds2011-01-11
|\
| * microblaze: Correct PVR access macrosroel kluin2011-01-03
* | of/net: Move of_get_mac_address() to a common source file.David Daney2010-11-01
|/
* mm: remove pte_*map_nested()Peter Zijlstra2010-10-26
* Merge branch 'next' of git://git.monstr.eu/linux-2.6-microblazeLinus Torvalds2010-10-25
|\
| * microblaze: Support timer on AXI liteMichal Simek2010-10-21
| * microblaze: Add support for little-endian MicroblazeMichal Simek2010-10-21
| * microblaze: Add PVR for endians plus detectionMichal Simek2010-10-21
| * microblaze: trivial: Add comment for AXI pvrMichal Simek2010-10-21
| * microblaze: Support early console on uart16550Michal Simek2010-10-21
| * microblaze: remove early printk uarlite console dependency from headerMichal Simek2010-10-21
| * microblaze: Define VMALLOC_START/ENDMichal Simek2010-10-21
| * microblaze: support gpio_to_irq()Michal Simek2010-10-21
| * microblaze: Define empty mmiowbMichal Simek2010-10-21
| * microblaze: wire up prlimit64 and fanotify* syscallsMichal Simek2010-10-21
| * microblaze: use asm-generic/pci-dma-compat.hFUJITA Tomonori2010-10-21
| * microblaze: Add PVR for BTCMichal Simek2010-10-21
| * microblaze: Removing dead CONTIGUOUS_PAGE_ALLOC config optionChristian Dietrich2010-10-21
| * microblaze: Report if only one timer is usedMichal Simek2010-10-21
| * microblaze: remove unused TIF_KERNEL_TRACEMichal Simek2010-10-21
| * microblaze: Add seccomp supportMichal Simek2010-10-21
| * microblaze: trivial: thread_info cleanupMichal Simek2010-10-21
| * microblaze: Fix pmd_populate macroMichal Simek2010-10-21
generated by cgit v1.2.2 (git 2.25.0) at 2026-06-01 00:13:13 -0400
' href='#n543'>543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 
/* filter engine-based seccomp system call filtering
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) 2011 The Chromium OS Authors <chromium-os-dev@chromium.org>
 */

#include <linux/compat.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/ftrace_event.h>
#include <linux/kallsyms.h>
#include <linux/kref.h>
#include <linux/perf_event.h>
#include <linux/prctl.h>
#include <linux/seccomp.h>
#include <linux/seq_file.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

#include <asm/syscall.h>
#include <trace/syscall.h>

/* Pull in *just* to access event_filter->filter_string. */
#include "trace/trace.h"

#define SECCOMP_MAX_FILTER_LENGTH MAX_FILTER_STR_VAL

#define SECCOMP_FILTER_ALLOW "1"
#define SECCOMP_ACTION_DENY 0xffff
#define SECCOMP_ACTION_ALLOW 0xfffe

/**
 * struct seccomp_filters - container for seccomp filters
 *
 * @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 shared filters across tasks.
 * @flags: anonymous struct to wrap filters-specific flags
 * @syscalls: array of 16-bit indices into @event_filters by syscall_nr
 *            May also be SECCOMP_ACTION_DENY or SECCOMP_ACTION_ALLOW
 * @count: size of @event_filters
 * @event_filters: array of pointers to ftrace event filters
 *
 * seccomp_filters objects should never be modified after being attached
 * to a task_struct.
 */
struct seccomp_filters {
	struct kref usage;
	struct {
		uint32_t compat:1,
			 __reserved:31;
	} flags;
	uint16_t syscalls[NR_syscalls];
	uint16_t count;
	struct event_filter *event_filters[0];
};

/* Make sure we can get to the syscall metadata that ftrace hordes. */
extern struct syscall_metadata *__start_syscalls_metadata[];
extern struct syscall_metadata *__stop_syscalls_metadata[];

static struct syscall_metadata **syscalls_metadata;
static struct syscall_metadata *syscall_nr_to_meta(int nr)
{
	if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
		return NULL;

	return syscalls_metadata[nr];
}

/*
 * Make ftrace support optional
 */

#if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PERF_EVENTS)

/* Fix up buffer creation to allow the ftrace filter engine to
 * work with seccomp filter events.
 * Lifted from kernel/trace/trace_syscalls.c
 */

#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
{
	/*
	 * Only compare after the "sys" prefix. Archs that use
	 * syscall wrappers may have syscalls symbols aliases prefixed
	 * with "SyS" instead of "sys", leading to an unwanted
	 * mismatch.
	 */
	return !strcmp(sym + 3, name + 3);
}
#endif

static __init struct syscall_metadata *
find_syscall_meta(unsigned long syscall)
{
	struct syscall_metadata **start;
	struct syscall_metadata **stop;
	char str[KSYM_SYMBOL_LEN];


	start = __start_syscalls_metadata;
	stop = __stop_syscalls_metadata;
	kallsyms_lookup(syscall, NULL, NULL, NULL, str);

	if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
		return NULL;

	for ( ; start < stop; start++) {
		if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
			return *start;
	}
	return NULL;
}

int __init init_seccomp_filter(void)
{
	struct syscall_metadata *meta;
	unsigned long addr;
	int i;

	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
					NR_syscalls, GFP_KERNEL);
	if (!syscalls_metadata) {
		WARN_ON(1);
		return -ENOMEM;
	}

	for (i = 0; i < NR_syscalls; i++) {
		addr = arch_syscall_addr(i);
		meta = find_syscall_meta(addr);
		if (!meta)
			continue;

		meta->syscall_nr = i;
		syscalls_metadata[i] = meta;
	}

	return 0;
}
core_initcall(init_seccomp_filter);

/*
 * End of the ftrace metadata access fixup.
 */


static int create_event_filter(struct event_filter **filter,
			       int event_type,
			       char *filter_string)
{
	int ret = -ENOSYS;
	struct perf_event event;
	event.filter = NULL;
	ret = ftrace_profile_set_filter(&event, event_type, filter_string);
	if (ret)
		goto out;
	*filter = event.filter;
	(*filter)->filter_string = kstrdup(filter_string, GFP_KERNEL);
	if (!(*filter)->filter_string) {
		ftrace_profile_free_filter(&event);
		ret = -ENOMEM;
	}
out:
	return ret;
}

static char *get_filter_string(struct event_filter *filter)
{
	if (filter)
		return filter->filter_string;
	return NULL;
}

static void free_event_filter(struct event_filter *filter)
{
	struct perf_event event;
	if (!filter)
		return;
	event.filter = filter;
	ftrace_profile_free_filter(&event);
}

/* ftrace_syscall_enter_state_size - returns the state size required.
 *
 * @nb_args: number of system call args expected.
 *           a negative value implies the maximum allowed.
 */
static size_t ftrace_syscall_enter_state_size(int nb_args)
{
	/* syscall_get_arguments only supports up to 6 arguments. */
	int arg_count = (nb_args >= 0 ? nb_args : 6);
	size_t size = (sizeof(unsigned long) * arg_count) +
		      sizeof(struct syscall_trace_enter);
	size = ALIGN(size + sizeof(u32), sizeof(u64));
	size -= sizeof(u32);
	return size;
}

#if 0  /* If we need exit interception. */
static size_t ftrace_syscall_exit_state_size(void)
{
	return ALIGN(sizeof(struct syscall_trace_exit) + sizeof(u32),
		     sizeof(u64)) - sizeof(u32);
}
#endif

/* ftrace_syscall_enter_state - build state for filter matching
 *
 * @buf: buffer to populate with current task state for matching
 * @available: size available for use in the buffer.
 * @entry: optional pointer to the trace_entry member of the state.
 *
 * Returns 0 on success and non-zero otherwise.
 * If @entry is NULL, it will be ignored.
 */
static int ftrace_syscall_enter_state(u8 *buf, size_t available,
				      struct trace_entry **entry)
{
	struct syscall_trace_enter *sys_enter;
	struct syscall_metadata *sys_data;
	int size;
	int syscall_nr;
	struct pt_regs *regs = task_pt_regs(current);

	syscall_nr = syscall_get_nr(current, regs);
	if (syscall_nr < 0)
		return -EINVAL;

	sys_data = syscall_nr_to_meta(syscall_nr);
	if (!sys_data)
		return -EINVAL;

	/* Determine the actual size needed. */
	size = ftrace_syscall_enter_state_size(sys_data->nb_args);
	BUG_ON(size > available);
	sys_enter = (struct syscall_trace_enter *)buf;

	/* Populating the struct trace_sys_enter is left to the caller, but
	 * a pointer is returned to encourage opacity.
	 */
	if (entry)
		*entry = &sys_enter->ent;

	sys_enter->nr = syscall_nr;
	syscall_get_arguments(current, regs, 0, sys_data->nb_args,
			      sys_enter->args);
	return 0;
}

#else  /*  defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PERF_EVENTS) */

#define create_event_filter(_ef_pptr, _event_type, _str) (-ENOSYS)
#define get_filter_string(_ef) (NULL)
#define free_event_filter(_f) do { } while (0)

#endif

/**
 * seccomp_filters_alloc - allocates a new filters object
 * @count: count to allocate for the event_filters array
 *
 * Returns ERR_PTR on error or an allocated object.
 */
static struct seccomp_filters *seccomp_filters_alloc(uint16_t count)
{
	struct seccomp_filters *f;

	if (count >= SECCOMP_ACTION_ALLOW)
		return ERR_PTR(-EINVAL);

	f = kzalloc(sizeof(struct seccomp_filters) +
		    (count * sizeof(struct event_filter *)), GFP_KERNEL);
	if (!f)
		return ERR_PTR(-ENOMEM);

	/* Lazy SECCOMP_ACTION_DENY assignment. */
	memset(f->syscalls, 0xff, sizeof(f->syscalls));
	kref_init(&f->usage);

	f->count = count;
	if (!count)
		return f;

	return f;
}

/**
 * seccomp_filters_free - cleans up the filter list and frees the table
 * @filters: NULL or live object to be completely destructed.
 */
static void seccomp_filters_free(struct seccomp_filters *filters)
{
	uint16_t count = 0;
	if (!filters)
		return;
	while (count < filters->count) {
		struct event_filter *f = filters->event_filters[count];
		free_event_filter(f);
		count++;
	}
	kfree(filters);
}

static void __put_seccomp_filters(struct kref *kref)
{
	struct seccomp_filters *orig =
		container_of(kref, struct seccomp_filters, usage);
	seccomp_filters_free(orig);
}

#define seccomp_filter_allow(_id) ((_id) == SECCOMP_ACTION_ALLOW)
#define seccomp_filter_deny(_id) ((_id) == SECCOMP_ACTION_DENY)
#define seccomp_filter_dynamic(_id) \
	(!seccomp_filter_allow(_id) && !seccomp_filter_deny(_id))
static inline uint16_t seccomp_filter_id(const struct seccomp_filters *f,
					 int syscall_nr)
{
	if (!f)
		return SECCOMP_ACTION_DENY;
	return f->syscalls[syscall_nr];
}

static inline struct event_filter *seccomp_dynamic_filter(
		const struct seccomp_filters *filters, uint16_t id)
{
	if (!seccomp_filter_dynamic(id))
		return NULL;
	return filters->event_filters[id];
}

static inline void set_seccomp_filter_id(struct seccomp_filters *filters,
					 int syscall_nr, uint16_t id)
{
	filters->syscalls[syscall_nr] = id;
}

static inline void set_seccomp_filter(struct seccomp_filters *filters,
				      int syscall_nr, uint16_t id,
				      struct event_filter *dynamic_filter)
{
	filters->syscalls[syscall_nr] = id;
	if (seccomp_filter_dynamic(id))
		filters->event_filters[id] = dynamic_filter;
}

static struct event_filter *alloc_event_filter(int syscall_nr,
					       char *filter_string)
{
	struct syscall_metadata *data;
	struct event_filter *filter = NULL;
	int err;

	data = syscall_nr_to_meta(syscall_nr);
	/* Argument-based filtering only works on ftrace-hooked syscalls. */
	err = -ENOSYS;
	if (!data)
		goto fail;
	err = create_event_filter(&filter,
				  data->enter_event->event.type,
				  filter_string);
	if (err)
		goto fail;

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

/**
 * seccomp_filters_copy - copies filters from src to dst.
 *
 * @dst: seccomp_filters to populate.
 * @src: table to read from.
 * @skip: specifies an entry, by system call, to skip.
 *
 * Returns non-zero on failure.
 * Both the source and the destination should have no simultaneous
 * writers, and dst should be exclusive to the caller.
 * If @skip is < 0, it is ignored.
 */
static int seccomp_filters_copy(struct seccomp_filters *dst,
				const struct seccomp_filters *src,
				int skip)
{
	int id = 0, ret = 0, nr;
	memcpy(&dst->flags, &src->flags, sizeof(src->flags));
	memcpy(dst->syscalls, src->syscalls, sizeof(dst->syscalls));
	if (!src->count)
		goto done;
	for (nr = 0; nr < NR_syscalls; ++nr) {
		struct event_filter *filter;
		char *str;
		uint16_t src_id = seccomp_filter_id(src, nr);
		if (nr == skip) {
			set_seccomp_filter(dst, nr, SECCOMP_ACTION_DENY,
					   NULL);
			continue;
		}
		if (!seccomp_filter_dynamic(src_id))
			continue;
		if (id >= dst->count) {
			ret = -EINVAL;
			goto done;
		}
		str = get_filter_string(seccomp_dynamic_filter(src, src_id));
		filter = alloc_event_filter(nr, str);
		if (IS_ERR(filter)) {
			ret = PTR_ERR(filter);
			goto done;
		}
		set_seccomp_filter(dst, nr, id, filter);
		id++;
	}

done:
	return ret;
}

/**
 * seccomp_extend_filter - appends more text to a syscall_nr's filter
 * @filters: unattached filter object to operate on
 * @syscall_nr: syscall number to update filters for
 * @filter_string: string to append to the existing filter
 *
 * The new string will be &&'d to the original filter string to ensure that it
 * always matches the existing predicates or less:
 *   (old_filter) && @filter_string
 * A new seccomp_filters instance is returned on success and a ERR_PTR on
 * failure.
 */
static int seccomp_extend_filter(struct seccomp_filters *filters,
				 int syscall_nr, char *filter_string)
{
	struct event_filter *filter;
	uint16_t id = seccomp_filter_id(filters, syscall_nr);
	char *merged = NULL;
	int ret = -EINVAL, expected;

	/* No extending with a "1". */
	if (!strcmp(SECCOMP_FILTER_ALLOW, filter_string))
		goto out;

	/* ftrace events are not aware of CONFIG_COMPAT system calls and will
	 * use the incorrect argument metadata if enabled.
	 */
	ret = -ENOSYS;
	if (filters->flags.compat)
		goto out;

	filter = seccomp_dynamic_filter(filters, id);
	ret = -ENOENT;
	if (!filter)
		goto out;

	merged = kzalloc(SECCOMP_MAX_FILTER_LENGTH + 1, GFP_KERNEL);
	ret = -ENOMEM;
	if (!merged)
		goto out;

	/* Encapsulate the filter strings in parentheses to isolate operator
	 * precedence behavior.
	 */
	expected = snprintf(merged, SECCOMP_MAX_FILTER_LENGTH, "(%s) && (%s)",
			    get_filter_string(filter), filter_string);
	ret = -E2BIG;
	if (expected >= SECCOMP_MAX_FILTER_LENGTH || expected < 0)
		goto out;

	/* Free the old filter */
	free_event_filter(filter);
	set_seccomp_filter(filters, syscall_nr, id, NULL);

	/* Replace it */
	filter = alloc_event_filter(syscall_nr, merged);
	if (IS_ERR(filter)) {
		ret = PTR_ERR(filter);
		goto out;
	}
	set_seccomp_filter(filters, syscall_nr, id, filter);
	ret = 0;

out:
	kfree(merged);
	return ret;
}

/**
 * seccomp_add_filter - adds a filter for an unfiltered syscall
 * @filters: filters object to add a filter/action to
 * @syscall_nr: system call number to add a filter for
 * @filter_string: the filter string to apply
 *
 * Returns 0 on success and non-zero otherwise.
 */
static int seccomp_add_filter(struct seccomp_filters *filters, int syscall_nr,
			      char *filter_string)
{
	struct event_filter *filter;
	int ret = 0;

	if (!strcmp(SECCOMP_FILTER_ALLOW, filter_string)) {
		set_seccomp_filter(filters, syscall_nr,
				   SECCOMP_ACTION_ALLOW, NULL);
		goto out;
	}

	/* ftrace events are not aware of CONFIG_COMPAT system calls and will
	 * use the incorrect argument metadata if enabled.
	 */
	ret = -ENOSYS;
	if (filters->flags.compat)
		goto out;

	ret = 0;
	filter = alloc_event_filter(syscall_nr, filter_string);
	if (IS_ERR(filter)) {
		ret = PTR_ERR(filter);
		goto out;
	}
	/* Always add to the last slot available since additions are
	 * are only done one at a time.
	 */
	set_seccomp_filter(filters, syscall_nr, filters->count - 1, filter);
out:
	return ret;
}

/* Wrap optional ftrace syscall support. Returns 1 on match or 0 otherwise. */
static int filter_match_current(struct event_filter *event_filter)
{
	int err = 0;
#ifdef CONFIG_FTRACE_SYSCALLS
	uint8_t syscall_state[64];

	memset(syscall_state, 0, sizeof(syscall_state));

	/* The generic tracing entry can remain zeroed. */
	err = ftrace_syscall_enter_state(syscall_state, sizeof(syscall_state),
					 NULL);
	if (err)
		return 0;

	err = filter_match_preds(event_filter, syscall_state);
#endif
	return err;
}

static const char *syscall_nr_to_name(int syscall)
{
	const char *syscall_name = "unknown";
	struct syscall_metadata *data = syscall_nr_to_meta(syscall);
	if (data)
		syscall_name = data->name;
	return syscall_name;
}

/* Encodes translation from sys_enter events to system call numbers.
 * Returns -ENOSYS when the event doesn't match a system call or if
 * current is_compat_task().  ftrace has no awareness of CONFIG_COMPAT
 * yet.
 */
static int event_to_syscall_nr(int event_id)
{
	int nr, nosys = 1;
#ifdef CONFIG_COMPAT
	if (is_compat_task())
		return -ENOSYS;
#endif
	for (nr = 0; nr < NR_syscalls; ++nr) {
		struct syscall_metadata *data = syscall_nr_to_meta(nr);
		if (!data)
			continue;
		nosys = 0;
		if (data->enter_event->event.type == event_id)
			return nr;
	}
	if (nosys)
		return -ENOSYS;
	return -EINVAL;
}

static void filters_set_compat(struct seccomp_filters *filters)
{
#ifdef CONFIG_COMPAT
	if (is_compat_task())
		filters->flags.compat = 1;
#endif
}

static inline int filters_compat_mismatch(struct seccomp_filters *filters)
{
	int ret = 0;
	if (!filters)
		return 0;
#ifdef CONFIG_COMPAT
	if (!!(is_compat_task()) != filters->flags.compat)
		ret = 1;
#endif
	return ret;
}

static inline int syscall_is_execve(int syscall)
{
	int nr = __NR_execve;
#ifdef CONFIG_COMPAT
	if (is_compat_task())
		nr = __NR_seccomp_execve_32;
#endif
	return syscall == nr;
}

#ifndef KSTK_EIP
#define KSTK_EIP(x) 0L
#endif

void seccomp_filter_log_failure(int syscall)
{
	pr_info("%s[%d]: system call %d (%s) blocked at 0x%lx\n",
		current->comm, task_pid_nr(current), syscall,
		syscall_nr_to_name(syscall), KSTK_EIP(current));
}

/* put_seccomp_filters - decrements the ref count of @orig and may free. */
void put_seccomp_filters(struct seccomp_filters *orig)
{
	if (!orig)
		return;
	kref_put(&orig->usage, __put_seccomp_filters);
}

/* get_seccomp_filters - increments the reference count of @orig. */
struct seccomp_filters *get_seccomp_filters(struct seccomp_filters *orig)
{
	if (!orig)
		return NULL;
	/* XXX: kref needs overflow prevention support. */
	kref_get(&orig->usage);
	return orig;
}

/**
 * seccomp_test_filters - tests 'current' against the given syscall
 * @syscall: number of the system call to test
 *
 * Returns 0 on ok and non-zero on error/failure.
 */
int seccomp_test_filters(int syscall)
{
	uint16_t id;
	struct event_filter *filter;
	struct seccomp_filters *filters;
	int ret = -EACCES;

	mutex_lock(&current->seccomp.filters_guard);
	/* No reference counting is done. filters_guard should protect the
	 * lifetime of any existing pointer below.
	 */
	filters = current->seccomp.filters;
	if (!filters)
		goto out;

	if (filters_compat_mismatch(filters)) {
		pr_info("%s[%d]: seccomp_filter compat() mismatch.\n",
			current->comm, task_pid_nr(current));
		goto out;
	}

	/* execve is never allowed. */
	if (syscall_is_execve(syscall))
		goto out;

	ret = 0;
	id = seccomp_filter_id(filters, syscall);
	if (seccomp_filter_allow(id))
		goto out;

	ret = -EACCES;
	if (!seccomp_filter_dynamic(id))
		goto out;

	filter = seccomp_dynamic_filter(filters, id);
	if (filter && filter_match_current(filter))
		ret = 0;
out:
	mutex_unlock(&current->seccomp.filters_guard);
	return ret;
}

/**
 * seccomp_show_filters - prints the current filter state to a seq_file
 * @filters: properly get()'d filters object
 * @m: the prepared seq_file to receive the data
 *
 * Returns 0 on a successful write.
 */
int seccomp_show_filters(struct seccomp_filters *filters, struct seq_file *m)
{
	int syscall;
	if (!filters)
		goto out;

	for (syscall = 0; syscall < NR_syscalls; ++syscall) {
		uint16_t id = seccomp_filter_id(filters, syscall);
		const char *filter_string = SECCOMP_FILTER_ALLOW;
		if (seccomp_filter_deny(id))
			continue;
		seq_printf(m, "%d (%s): ",
			      syscall,
			      syscall_nr_to_name(syscall));
		if (seccomp_filter_dynamic(id))
			filter_string = get_filter_string(
					  seccomp_dynamic_filter(filters, id));
		seq_printf(m, "%s\n", filter_string);
	}
out:
	return 0;
}
EXPORT_SYMBOL_GPL(seccomp_show_filters);

/**
 * seccomp_get_filter - copies the filter_string into "buf"
 * @syscall_nr: system call number to look up
 * @buf: destination buffer
 * @bufsize: available space in the buffer.
 *
 * Context: User context only. This function may sleep on allocation and
 *          operates on current. current must be attempting a system call
 *          when this is called.
 *
 * Looks up the filter for the given system call number on current.  If found,
 * the string length of the NUL-terminated buffer is returned and < 0 is
 * returned on error. The NUL byte is not included in the length.
 */
long seccomp_get_filter(int syscall_nr, char *buf, unsigned long bufsize)
{
	struct seccomp_filters *filters;
	struct event_filter *filter;
	long ret = -EINVAL;
	uint16_t id;

	if (bufsize > SECCOMP_MAX_FILTER_LENGTH)
		bufsize = SECCOMP_MAX_FILTER_LENGTH;

	mutex_lock(&current->seccomp.filters_guard);
	filters = current->seccomp.filters;

	if (!filters)
		goto out;

	ret = -ENOENT;
	id = seccomp_filter_id(filters, syscall_nr);
	if (seccomp_filter_deny(id))
		goto out;

	if (seccomp_filter_allow(id)) {
		ret = strlcpy(buf, SECCOMP_FILTER_ALLOW, bufsize);
		goto copied;
	}

	filter = seccomp_dynamic_filter(filters, id);
	if (!filter)
		goto out;
	ret = strlcpy(buf, get_filter_string(filter), bufsize);

copied:
	if (ret >= bufsize) {
		ret = -ENOSPC;
		goto out;
	}
out:
	mutex_unlock(&current->seccomp.filters_guard);
	return ret;
}
EXPORT_SYMBOL_GPL(seccomp_get_filter);

/**
 * seccomp_clear_filter: clears the seccomp filter for a syscall.
 * @syscall_nr: the system call number to clear filters for.
 *
 * Context: User context only. This function may sleep on allocation and
 *          operates on current. current must be attempting a system call
 *          when this is called.
 *
 * Returns 0 on success.
 */
long seccomp_clear_filter(int syscall_nr)
{
	struct seccomp_filters *filters = NULL, *orig_filters;
	uint16_t id;
	int ret = -EINVAL;

	mutex_lock(&current->seccomp.filters_guard);
	orig_filters = current->seccomp.filters;

	if (!orig_filters)
		goto out;

	if (filters_compat_mismatch(orig_filters))
		goto out;

	id = seccomp_filter_id(orig_filters, syscall_nr);
	if (seccomp_filter_deny(id))
		goto out;

	/* Create a new filters object for the task */
	if (seccomp_filter_dynamic(id))
		filters = seccomp_filters_alloc(orig_filters->count - 1);
	else
		filters = seccomp_filters_alloc(orig_filters->count);

	if (IS_ERR(filters)) {
		ret = PTR_ERR(filters);
		goto out;
	}

	/* Copy, but drop the requested entry. */
	ret = seccomp_filters_copy(filters, orig_filters, syscall_nr);
	if (ret)
		goto out;
	get_seccomp_filters(filters);  /* simplify the out: path */

	current->seccomp.filters = filters;
	put_seccomp_filters(orig_filters);  /* for the task */
out:
	put_seccomp_filters(filters);  /* for the extra get */
	mutex_unlock(&current->seccomp.filters_guard);
	return ret;
}
EXPORT_SYMBOL_GPL(seccomp_clear_filter);

/**
 * seccomp_set_filter: - Adds/extends a seccomp filter for a syscall.
 * @syscall_nr: system call number to apply the filter to.
 * @filter: ftrace filter string to apply.
 *
 * Context: User context only. This function may sleep on allocation and
 *          operates on current. current must be attempting a system call
 *          when this is called.
 *
 * New filters may be added for system calls when the current task is
 * not in a secure computing mode (seccomp).  Otherwise, existing filters may
 * be extended.
 *
 * Returns 0 on success or an errno on failure.
 */
long seccomp_set_filter(int syscall_nr, char *filter)
{
	struct seccomp_filters *filters = NULL, *orig_filters = NULL;
	uint16_t id;
	long ret = -EINVAL;
	uint16_t filters_needed;

	mutex_lock(&current->seccomp.filters_guard);
	if (!filter)
		goto out;

	filter = strstrip(filter);
	/* Disallow empty strings. */
	if (filter[0] == 0)
		goto out;

	orig_filters = current->seccomp.filters;

	/* After the first call, compatibility mode is selected permanently. */
	ret = -EACCES;
	if (filters_compat_mismatch(orig_filters))
		goto out;

	filters_needed = orig_filters ? orig_filters->count : 0;
	id = seccomp_filter_id(orig_filters, syscall_nr);
	if (seccomp_filter_deny(id)) {
		/* Don't allow DENYs to be changed when in a seccomp mode */
		ret = -EACCES;
		if (current->seccomp.mode)
			goto out;
		filters_needed++;
	}

	filters = seccomp_filters_alloc(filters_needed);
	if (IS_ERR(filters)) {
		ret = PTR_ERR(filters);
		goto out;
	}

	filters_set_compat(filters);
	if (orig_filters) {
		ret = seccomp_filters_copy(filters, orig_filters, -1);
		if (ret)
			goto out;
	}

	if (seccomp_filter_deny(id))
		ret = seccomp_add_filter(filters, syscall_nr, filter);
	else
		ret = seccomp_extend_filter(filters, syscall_nr, filter);
	if (ret)
		goto out;
	get_seccomp_filters(filters);  /* simplify the error paths */

	current->seccomp.filters = filters;
	put_seccomp_filters(orig_filters);  /* for the task */
out:
	put_seccomp_filters(filters);  /* for get or task, on err */
	mutex_unlock(&current->seccomp.filters_guard);
	return ret;
}
EXPORT_SYMBOL_GPL(seccomp_set_filter);

long prctl_set_seccomp_filter(unsigned long id_type,
			      unsigned long id,
			      char __user *user_filter)
{
	int nr;
	long ret;
	char *filter = NULL;

	ret = -EINVAL;
	if (id_type != PR_SECCOMP_FILTER_EVENT &&
	    id_type != PR_SECCOMP_FILTER_SYSCALL)
		goto out;

	if (id > (unsigned long) INT_MAX)
		goto out;
	nr = (int) id;

	if (id_type == PR_SECCOMP_FILTER_EVENT)
		nr = event_to_syscall_nr(nr);

	if (nr < 0) {
		ret = nr;
		goto out;
	}

	if (nr >= NR_syscalls)
		goto out;

	ret = -EFAULT;
	if (!user_filter)
		goto out;

	filter = kzalloc(SECCOMP_MAX_FILTER_LENGTH + 1, GFP_KERNEL);
	ret = -ENOMEM;
	if (!filter)
		goto out;

	ret = -EFAULT;
	if (strncpy_from_user(filter, user_filter,
			      SECCOMP_MAX_FILTER_LENGTH - 1) < 0)
		goto out;

	ret = seccomp_set_filter(nr, filter);

out:
	kfree(filter);
	return ret;
}

long prctl_clear_seccomp_filter(unsigned long id_type, unsigned long id)
{
	int nr = -1;
	long ret = -EINVAL;

	if (id_type != PR_SECCOMP_FILTER_EVENT &&
	    id_type != PR_SECCOMP_FILTER_SYSCALL)
		goto out;

	if (id > (unsigned long) INT_MAX)
		goto out;

	nr = (int) id;
	if (id_type == PR_SECCOMP_FILTER_EVENT)
		nr = event_to_syscall_nr(nr);

	if (nr < 0) {
		ret = nr;
		goto out;
	}

	if (nr >= NR_syscalls)
		goto out;

	ret = seccomp_clear_filter(nr);

out:
	return ret;
}

long prctl_get_seccomp_filter(unsigned long id_type, unsigned long id,
			      char __user *dst, unsigned long available)
{
	unsigned long copied;
	char *buf = NULL;
	int nr, ret = -EINVAL;

	if (!available)
		goto out;

	/* Ignore extra buffer space. */
	if (available > SECCOMP_MAX_FILTER_LENGTH)
		available = SECCOMP_MAX_FILTER_LENGTH;

	if (id_type != PR_SECCOMP_FILTER_EVENT &&
	    id_type != PR_SECCOMP_FILTER_SYSCALL)
		goto out;

	if (id > (unsigned long) INT_MAX)
		goto out;
	nr = (int) id;

	if (id_type == PR_SECCOMP_FILTER_EVENT)
		nr = event_to_syscall_nr(nr);

	if (nr < 0) {
		ret = nr;
		goto out;
	}

	if (nr >= NR_syscalls)
		goto out;

	ret = -ENOMEM;
	buf = kzalloc(available, GFP_KERNEL);
	if (!buf)
		goto out;

	ret = seccomp_get_filter(nr, buf, available);
	if (ret < 0)
		goto out;

	/* Include the NUL byte in the copy. */
	copied = copy_to_user(dst, buf, ret + 1);
	ret = -ENOSPC;
	if (copied)
		goto out;
	ret = 0;
out:
	kfree(buf);
	return ret;
}
generated by cgit v1.2.2 (git 2.25.0) at 2026-06-01 00:13:12 -0400