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![Linus Torvalds](/assets/img/avatar_default.png)
This replaces the prior support for Clang's standard Control Flow Integrity (CFI) instrumentation, which has required a lot of special conditions (e.g. LTO) and work-arounds. The current implementation ("Kernel CFI") is specific to C, directly designed for the Linux kernel, and takes advantage of architectural features like x86's IBT. This series retains arm64 support and adds x86 support. Additional "generic" architectural support is expected soon: https://github.com/samitolvanen/llvm-project/commits/kcfi_generic - treewide: Remove old CFI support details - arm64: Replace Clang CFI support with Clang KCFI support - x86: Introduce Clang KCFI support -----BEGIN PGP SIGNATURE----- iQJKBAABCgA0FiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmM4aAUWHGtlZXNjb29r QGNocm9taXVtLm9yZwAKCRCJcvTf3G3AJkgWD/4mUgb7xewNIG/+fuipGd620Iao K0T8q4BNxLNRltOxNc3Q0WMDCggX0qJGCeds7EdFQJQOGxWcbifM8MAS4idAGM0G fc3Gxl1imC/oF6goCAbQgndA6jYFIWXGsv8LsRjAXRidWLFr3GFAqVqYJyokSySr 8zMQsEDuF4I1gQnOhEWdtPZbV3MQ4ZjfFzpv+33agbq6Gb72vKvDh3G6g2VXlxjt 1qnMtS+eEpbBU65cJkOi4MSLgymWbnIAeTMb0dbsV4kJ08YoTl8uz1B+weeH6GgT WP73ZJ4nqh1kkkT9EqS9oKozNB9fObhvCokEuAjuQ7i1eCEZsbShvRc0iL7OKTGG UfuTJa5qQ4h7Z0JS35FCSJETa+fcG0lTyEd133nLXLMZP9K2antf+A6O//fd0J1V Jg4VN7DQmZ+UNGOzRkL6dTtQUy4PkxhniIloaClfSYXxhNirA+v//sHTnTK3z2Bl 6qceYqmFmns2Laual7+lvnZgt6egMBcmAL/MOdbU74+KIR9Xw76wxQjifktHX+WF FEUQkUJDB5XcUyKlbvHoqobRMxvEZ8RIlC5DIkgFiPRE3TI0MqfzNSFnQ/6+lFNg Y0AS9HYJmcj8sVzAJ7ji24WPFCXzsbFn6baJa9usDNbWyQZokYeiv7ZPNPHPDVrv YEBP6aYko0lVSUS9qw== =Li4D -----END PGP SIGNATURE----- Merge tag 'kcfi-v6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull kcfi updates from Kees Cook: "This replaces the prior support for Clang's standard Control Flow Integrity (CFI) instrumentation, which has required a lot of special conditions (e.g. LTO) and work-arounds. The new implementation ("Kernel CFI") is specific to C, directly designed for the Linux kernel, and takes advantage of architectural features like x86's IBT. This series retains arm64 support and adds x86 support. GCC support is expected in the future[1], and additional "generic" architectural support is expected soon[2]. Summary: - treewide: Remove old CFI support details - arm64: Replace Clang CFI support with Clang KCFI support - x86: Introduce Clang KCFI support" Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107048 [1] Link: https://github.com/samitolvanen/llvm-project/commits/kcfi_generic [2] * tag 'kcfi-v6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (22 commits) x86: Add support for CONFIG_CFI_CLANG x86/purgatory: Disable CFI x86: Add types to indirectly called assembly functions x86/tools/relocs: Ignore __kcfi_typeid_ relocations kallsyms: Drop CONFIG_CFI_CLANG workarounds objtool: Disable CFI warnings objtool: Preserve special st_shndx indexes in elf_update_symbol treewide: Drop __cficanonical treewide: Drop WARN_ON_FUNCTION_MISMATCH treewide: Drop function_nocfi init: Drop __nocfi from __init arm64: Drop unneeded __nocfi attributes arm64: Add CFI error handling arm64: Add types to indirect called assembly functions psci: Fix the function type for psci_initcall_t lkdtm: Emit an indirect call for CFI tests cfi: Add type helper macros cfi: Switch to -fsanitize=kcfi cfi: Drop __CFI_ADDRESSABLE cfi: Remove CONFIG_CFI_CLANG_SHADOW ...
961 lines
24 KiB
C
961 lines
24 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
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*
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* Rewritten and vastly simplified by Rusty Russell for in-kernel
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* module loader:
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* Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
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*
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* ChangeLog:
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*
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* (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
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* Changed the compression method from stem compression to "table lookup"
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* compression (see scripts/kallsyms.c for a more complete description)
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*/
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#include <linux/kallsyms.h>
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#include <linux/init.h>
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#include <linux/seq_file.h>
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#include <linux/fs.h>
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#include <linux/kdb.h>
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#include <linux/err.h>
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#include <linux/proc_fs.h>
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#include <linux/sched.h> /* for cond_resched */
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#include <linux/ctype.h>
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#include <linux/slab.h>
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#include <linux/filter.h>
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#include <linux/ftrace.h>
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#include <linux/kprobes.h>
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#include <linux/build_bug.h>
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#include <linux/compiler.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/bsearch.h>
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#include <linux/btf_ids.h>
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#include "kallsyms_internal.h"
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/*
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* Expand a compressed symbol data into the resulting uncompressed string,
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* if uncompressed string is too long (>= maxlen), it will be truncated,
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* given the offset to where the symbol is in the compressed stream.
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*/
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static unsigned int kallsyms_expand_symbol(unsigned int off,
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char *result, size_t maxlen)
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{
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int len, skipped_first = 0;
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const char *tptr;
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const u8 *data;
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/* Get the compressed symbol length from the first symbol byte. */
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data = &kallsyms_names[off];
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len = *data;
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data++;
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off++;
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/* If MSB is 1, it is a "big" symbol, so needs an additional byte. */
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if ((len & 0x80) != 0) {
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len = (len & 0x7F) | (*data << 7);
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data++;
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off++;
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}
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/*
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* Update the offset to return the offset for the next symbol on
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* the compressed stream.
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*/
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off += len;
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/*
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* For every byte on the compressed symbol data, copy the table
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* entry for that byte.
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*/
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while (len) {
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tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
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data++;
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len--;
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while (*tptr) {
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if (skipped_first) {
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if (maxlen <= 1)
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goto tail;
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*result = *tptr;
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result++;
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maxlen--;
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} else
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skipped_first = 1;
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tptr++;
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}
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}
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tail:
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if (maxlen)
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*result = '\0';
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/* Return to offset to the next symbol. */
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return off;
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}
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/*
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* Get symbol type information. This is encoded as a single char at the
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* beginning of the symbol name.
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*/
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static char kallsyms_get_symbol_type(unsigned int off)
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{
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/*
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* Get just the first code, look it up in the token table,
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* and return the first char from this token.
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*/
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return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
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}
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/*
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* Find the offset on the compressed stream given and index in the
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* kallsyms array.
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*/
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static unsigned int get_symbol_offset(unsigned long pos)
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{
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const u8 *name;
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int i, len;
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/*
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* Use the closest marker we have. We have markers every 256 positions,
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* so that should be close enough.
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*/
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name = &kallsyms_names[kallsyms_markers[pos >> 8]];
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/*
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* Sequentially scan all the symbols up to the point we're searching
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* for. Every symbol is stored in a [<len>][<len> bytes of data] format,
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* so we just need to add the len to the current pointer for every
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* symbol we wish to skip.
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*/
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for (i = 0; i < (pos & 0xFF); i++) {
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len = *name;
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/*
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* If MSB is 1, it is a "big" symbol, so we need to look into
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* the next byte (and skip it, too).
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*/
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if ((len & 0x80) != 0)
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len = ((len & 0x7F) | (name[1] << 7)) + 1;
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name = name + len + 1;
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}
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return name - kallsyms_names;
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}
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static unsigned long kallsyms_sym_address(int idx)
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{
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if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
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return kallsyms_addresses[idx];
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/* values are unsigned offsets if --absolute-percpu is not in effect */
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if (!IS_ENABLED(CONFIG_KALLSYMS_ABSOLUTE_PERCPU))
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return kallsyms_relative_base + (u32)kallsyms_offsets[idx];
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/* ...otherwise, positive offsets are absolute values */
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if (kallsyms_offsets[idx] >= 0)
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return kallsyms_offsets[idx];
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/* ...and negative offsets are relative to kallsyms_relative_base - 1 */
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return kallsyms_relative_base - 1 - kallsyms_offsets[idx];
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}
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static bool cleanup_symbol_name(char *s)
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{
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char *res;
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if (!IS_ENABLED(CONFIG_LTO_CLANG))
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return false;
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/*
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* LLVM appends various suffixes for local functions and variables that
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* must be promoted to global scope as part of LTO. This can break
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* hooking of static functions with kprobes. '.' is not a valid
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* character in an identifier in C. Suffixes observed:
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* - foo.llvm.[0-9a-f]+
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* - foo.[0-9a-f]+
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*/
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res = strchr(s, '.');
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if (res) {
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*res = '\0';
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return true;
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}
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return false;
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}
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/* Lookup the address for this symbol. Returns 0 if not found. */
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unsigned long kallsyms_lookup_name(const char *name)
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{
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char namebuf[KSYM_NAME_LEN];
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unsigned long i;
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unsigned int off;
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/* Skip the search for empty string. */
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if (!*name)
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return 0;
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for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
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off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
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if (strcmp(namebuf, name) == 0)
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return kallsyms_sym_address(i);
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if (cleanup_symbol_name(namebuf) && strcmp(namebuf, name) == 0)
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return kallsyms_sym_address(i);
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}
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return module_kallsyms_lookup_name(name);
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}
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/*
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* Iterate over all symbols in vmlinux. For symbols from modules use
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* module_kallsyms_on_each_symbol instead.
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*/
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int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
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unsigned long),
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void *data)
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{
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char namebuf[KSYM_NAME_LEN];
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unsigned long i;
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unsigned int off;
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int ret;
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for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
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off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf));
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ret = fn(data, namebuf, NULL, kallsyms_sym_address(i));
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if (ret != 0)
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return ret;
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cond_resched();
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}
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return 0;
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}
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static unsigned long get_symbol_pos(unsigned long addr,
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unsigned long *symbolsize,
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unsigned long *offset)
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{
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unsigned long symbol_start = 0, symbol_end = 0;
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unsigned long i, low, high, mid;
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/* This kernel should never had been booted. */
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if (!IS_ENABLED(CONFIG_KALLSYMS_BASE_RELATIVE))
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BUG_ON(!kallsyms_addresses);
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else
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BUG_ON(!kallsyms_offsets);
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/* Do a binary search on the sorted kallsyms_addresses array. */
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low = 0;
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high = kallsyms_num_syms;
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while (high - low > 1) {
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mid = low + (high - low) / 2;
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if (kallsyms_sym_address(mid) <= addr)
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low = mid;
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else
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high = mid;
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}
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/*
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* Search for the first aliased symbol. Aliased
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* symbols are symbols with the same address.
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*/
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while (low && kallsyms_sym_address(low-1) == kallsyms_sym_address(low))
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--low;
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symbol_start = kallsyms_sym_address(low);
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/* Search for next non-aliased symbol. */
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for (i = low + 1; i < kallsyms_num_syms; i++) {
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if (kallsyms_sym_address(i) > symbol_start) {
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symbol_end = kallsyms_sym_address(i);
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break;
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}
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}
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/* If we found no next symbol, we use the end of the section. */
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if (!symbol_end) {
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if (is_kernel_inittext(addr))
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symbol_end = (unsigned long)_einittext;
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else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
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symbol_end = (unsigned long)_end;
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else
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symbol_end = (unsigned long)_etext;
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}
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if (symbolsize)
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*symbolsize = symbol_end - symbol_start;
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if (offset)
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*offset = addr - symbol_start;
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return low;
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}
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/*
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* Lookup an address but don't bother to find any names.
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*/
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int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
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unsigned long *offset)
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{
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char namebuf[KSYM_NAME_LEN];
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if (is_ksym_addr(addr)) {
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get_symbol_pos(addr, symbolsize, offset);
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return 1;
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}
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return !!module_address_lookup(addr, symbolsize, offset, NULL, NULL, namebuf) ||
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!!__bpf_address_lookup(addr, symbolsize, offset, namebuf);
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}
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static const char *kallsyms_lookup_buildid(unsigned long addr,
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unsigned long *symbolsize,
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unsigned long *offset, char **modname,
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const unsigned char **modbuildid, char *namebuf)
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{
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const char *ret;
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namebuf[KSYM_NAME_LEN - 1] = 0;
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namebuf[0] = 0;
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if (is_ksym_addr(addr)) {
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unsigned long pos;
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pos = get_symbol_pos(addr, symbolsize, offset);
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/* Grab name */
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kallsyms_expand_symbol(get_symbol_offset(pos),
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namebuf, KSYM_NAME_LEN);
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if (modname)
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*modname = NULL;
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if (modbuildid)
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*modbuildid = NULL;
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ret = namebuf;
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goto found;
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}
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/* See if it's in a module or a BPF JITed image. */
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ret = module_address_lookup(addr, symbolsize, offset,
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modname, modbuildid, namebuf);
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if (!ret)
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ret = bpf_address_lookup(addr, symbolsize,
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offset, modname, namebuf);
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if (!ret)
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ret = ftrace_mod_address_lookup(addr, symbolsize,
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offset, modname, namebuf);
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found:
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cleanup_symbol_name(namebuf);
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return ret;
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}
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/*
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* Lookup an address
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* - modname is set to NULL if it's in the kernel.
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* - We guarantee that the returned name is valid until we reschedule even if.
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* It resides in a module.
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* - We also guarantee that modname will be valid until rescheduled.
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*/
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const char *kallsyms_lookup(unsigned long addr,
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unsigned long *symbolsize,
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unsigned long *offset,
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char **modname, char *namebuf)
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{
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return kallsyms_lookup_buildid(addr, symbolsize, offset, modname,
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NULL, namebuf);
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}
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int lookup_symbol_name(unsigned long addr, char *symname)
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{
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int res;
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symname[0] = '\0';
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symname[KSYM_NAME_LEN - 1] = '\0';
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if (is_ksym_addr(addr)) {
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unsigned long pos;
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pos = get_symbol_pos(addr, NULL, NULL);
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/* Grab name */
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kallsyms_expand_symbol(get_symbol_offset(pos),
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symname, KSYM_NAME_LEN);
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goto found;
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}
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/* See if it's in a module. */
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res = lookup_module_symbol_name(addr, symname);
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if (res)
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return res;
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found:
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cleanup_symbol_name(symname);
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return 0;
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}
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|
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int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
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unsigned long *offset, char *modname, char *name)
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{
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int res;
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name[0] = '\0';
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name[KSYM_NAME_LEN - 1] = '\0';
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|
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if (is_ksym_addr(addr)) {
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unsigned long pos;
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pos = get_symbol_pos(addr, size, offset);
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/* Grab name */
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kallsyms_expand_symbol(get_symbol_offset(pos),
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name, KSYM_NAME_LEN);
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modname[0] = '\0';
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goto found;
|
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}
|
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/* See if it's in a module. */
|
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res = lookup_module_symbol_attrs(addr, size, offset, modname, name);
|
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if (res)
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return res;
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|
|
found:
|
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cleanup_symbol_name(name);
|
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return 0;
|
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}
|
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|
|
/* Look up a kernel symbol and return it in a text buffer. */
|
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static int __sprint_symbol(char *buffer, unsigned long address,
|
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int symbol_offset, int add_offset, int add_buildid)
|
|
{
|
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char *modname;
|
|
const unsigned char *buildid;
|
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const char *name;
|
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unsigned long offset, size;
|
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int len;
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|
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address += symbol_offset;
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name = kallsyms_lookup_buildid(address, &size, &offset, &modname, &buildid,
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buffer);
|
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if (!name)
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return sprintf(buffer, "0x%lx", address - symbol_offset);
|
|
|
|
if (name != buffer)
|
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strcpy(buffer, name);
|
|
len = strlen(buffer);
|
|
offset -= symbol_offset;
|
|
|
|
if (add_offset)
|
|
len += sprintf(buffer + len, "+%#lx/%#lx", offset, size);
|
|
|
|
if (modname) {
|
|
len += sprintf(buffer + len, " [%s", modname);
|
|
#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
|
|
if (add_buildid && buildid) {
|
|
/* build ID should match length of sprintf */
|
|
#if IS_ENABLED(CONFIG_MODULES)
|
|
static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
|
|
#endif
|
|
len += sprintf(buffer + len, " %20phN", buildid);
|
|
}
|
|
#endif
|
|
len += sprintf(buffer + len, "]");
|
|
}
|
|
|
|
return len;
|
|
}
|
|
|
|
/**
|
|
* sprint_symbol - Look up a kernel symbol and return it in a text buffer
|
|
* @buffer: buffer to be stored
|
|
* @address: address to lookup
|
|
*
|
|
* This function looks up a kernel symbol with @address and stores its name,
|
|
* offset, size and module name to @buffer if possible. If no symbol was found,
|
|
* just saves its @address as is.
|
|
*
|
|
* This function returns the number of bytes stored in @buffer.
|
|
*/
|
|
int sprint_symbol(char *buffer, unsigned long address)
|
|
{
|
|
return __sprint_symbol(buffer, address, 0, 1, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sprint_symbol);
|
|
|
|
/**
|
|
* sprint_symbol_build_id - Look up a kernel symbol and return it in a text buffer
|
|
* @buffer: buffer to be stored
|
|
* @address: address to lookup
|
|
*
|
|
* This function looks up a kernel symbol with @address and stores its name,
|
|
* offset, size, module name and module build ID to @buffer if possible. If no
|
|
* symbol was found, just saves its @address as is.
|
|
*
|
|
* This function returns the number of bytes stored in @buffer.
|
|
*/
|
|
int sprint_symbol_build_id(char *buffer, unsigned long address)
|
|
{
|
|
return __sprint_symbol(buffer, address, 0, 1, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sprint_symbol_build_id);
|
|
|
|
/**
|
|
* sprint_symbol_no_offset - Look up a kernel symbol and return it in a text buffer
|
|
* @buffer: buffer to be stored
|
|
* @address: address to lookup
|
|
*
|
|
* This function looks up a kernel symbol with @address and stores its name
|
|
* and module name to @buffer if possible. If no symbol was found, just saves
|
|
* its @address as is.
|
|
*
|
|
* This function returns the number of bytes stored in @buffer.
|
|
*/
|
|
int sprint_symbol_no_offset(char *buffer, unsigned long address)
|
|
{
|
|
return __sprint_symbol(buffer, address, 0, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(sprint_symbol_no_offset);
|
|
|
|
/**
|
|
* sprint_backtrace - Look up a backtrace symbol and return it in a text buffer
|
|
* @buffer: buffer to be stored
|
|
* @address: address to lookup
|
|
*
|
|
* This function is for stack backtrace and does the same thing as
|
|
* sprint_symbol() but with modified/decreased @address. If there is a
|
|
* tail-call to the function marked "noreturn", gcc optimized out code after
|
|
* the call so that the stack-saved return address could point outside of the
|
|
* caller. This function ensures that kallsyms will find the original caller
|
|
* by decreasing @address.
|
|
*
|
|
* This function returns the number of bytes stored in @buffer.
|
|
*/
|
|
int sprint_backtrace(char *buffer, unsigned long address)
|
|
{
|
|
return __sprint_symbol(buffer, address, -1, 1, 0);
|
|
}
|
|
|
|
/**
|
|
* sprint_backtrace_build_id - Look up a backtrace symbol and return it in a text buffer
|
|
* @buffer: buffer to be stored
|
|
* @address: address to lookup
|
|
*
|
|
* This function is for stack backtrace and does the same thing as
|
|
* sprint_symbol() but with modified/decreased @address. If there is a
|
|
* tail-call to the function marked "noreturn", gcc optimized out code after
|
|
* the call so that the stack-saved return address could point outside of the
|
|
* caller. This function ensures that kallsyms will find the original caller
|
|
* by decreasing @address. This function also appends the module build ID to
|
|
* the @buffer if @address is within a kernel module.
|
|
*
|
|
* This function returns the number of bytes stored in @buffer.
|
|
*/
|
|
int sprint_backtrace_build_id(char *buffer, unsigned long address)
|
|
{
|
|
return __sprint_symbol(buffer, address, -1, 1, 1);
|
|
}
|
|
|
|
/* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
|
|
struct kallsym_iter {
|
|
loff_t pos;
|
|
loff_t pos_arch_end;
|
|
loff_t pos_mod_end;
|
|
loff_t pos_ftrace_mod_end;
|
|
loff_t pos_bpf_end;
|
|
unsigned long value;
|
|
unsigned int nameoff; /* If iterating in core kernel symbols. */
|
|
char type;
|
|
char name[KSYM_NAME_LEN];
|
|
char module_name[MODULE_NAME_LEN];
|
|
int exported;
|
|
int show_value;
|
|
};
|
|
|
|
int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value,
|
|
char *type, char *name)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static int get_ksymbol_arch(struct kallsym_iter *iter)
|
|
{
|
|
int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms,
|
|
&iter->value, &iter->type,
|
|
iter->name);
|
|
|
|
if (ret < 0) {
|
|
iter->pos_arch_end = iter->pos;
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int get_ksymbol_mod(struct kallsym_iter *iter)
|
|
{
|
|
int ret = module_get_kallsym(iter->pos - iter->pos_arch_end,
|
|
&iter->value, &iter->type,
|
|
iter->name, iter->module_name,
|
|
&iter->exported);
|
|
if (ret < 0) {
|
|
iter->pos_mod_end = iter->pos;
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* ftrace_mod_get_kallsym() may also get symbols for pages allocated for ftrace
|
|
* purposes. In that case "__builtin__ftrace" is used as a module name, even
|
|
* though "__builtin__ftrace" is not a module.
|
|
*/
|
|
static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
|
|
{
|
|
int ret = ftrace_mod_get_kallsym(iter->pos - iter->pos_mod_end,
|
|
&iter->value, &iter->type,
|
|
iter->name, iter->module_name,
|
|
&iter->exported);
|
|
if (ret < 0) {
|
|
iter->pos_ftrace_mod_end = iter->pos;
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int get_ksymbol_bpf(struct kallsym_iter *iter)
|
|
{
|
|
int ret;
|
|
|
|
strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
|
|
iter->exported = 0;
|
|
ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
|
|
&iter->value, &iter->type,
|
|
iter->name);
|
|
if (ret < 0) {
|
|
iter->pos_bpf_end = iter->pos;
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* This uses "__builtin__kprobes" as a module name for symbols for pages
|
|
* allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
|
|
* module.
|
|
*/
|
|
static int get_ksymbol_kprobe(struct kallsym_iter *iter)
|
|
{
|
|
strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
|
|
iter->exported = 0;
|
|
return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
|
|
&iter->value, &iter->type,
|
|
iter->name) < 0 ? 0 : 1;
|
|
}
|
|
|
|
/* Returns space to next name. */
|
|
static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
|
|
{
|
|
unsigned off = iter->nameoff;
|
|
|
|
iter->module_name[0] = '\0';
|
|
iter->value = kallsyms_sym_address(iter->pos);
|
|
|
|
iter->type = kallsyms_get_symbol_type(off);
|
|
|
|
off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name));
|
|
|
|
return off - iter->nameoff;
|
|
}
|
|
|
|
static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
|
|
{
|
|
iter->name[0] = '\0';
|
|
iter->nameoff = get_symbol_offset(new_pos);
|
|
iter->pos = new_pos;
|
|
if (new_pos == 0) {
|
|
iter->pos_arch_end = 0;
|
|
iter->pos_mod_end = 0;
|
|
iter->pos_ftrace_mod_end = 0;
|
|
iter->pos_bpf_end = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The end position (last + 1) of each additional kallsyms section is recorded
|
|
* in iter->pos_..._end as each section is added, and so can be used to
|
|
* determine which get_ksymbol_...() function to call next.
|
|
*/
|
|
static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
|
|
{
|
|
iter->pos = pos;
|
|
|
|
if ((!iter->pos_arch_end || iter->pos_arch_end > pos) &&
|
|
get_ksymbol_arch(iter))
|
|
return 1;
|
|
|
|
if ((!iter->pos_mod_end || iter->pos_mod_end > pos) &&
|
|
get_ksymbol_mod(iter))
|
|
return 1;
|
|
|
|
if ((!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > pos) &&
|
|
get_ksymbol_ftrace_mod(iter))
|
|
return 1;
|
|
|
|
if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
|
|
get_ksymbol_bpf(iter))
|
|
return 1;
|
|
|
|
return get_ksymbol_kprobe(iter);
|
|
}
|
|
|
|
/* Returns false if pos at or past end of file. */
|
|
static int update_iter(struct kallsym_iter *iter, loff_t pos)
|
|
{
|
|
/* Module symbols can be accessed randomly. */
|
|
if (pos >= kallsyms_num_syms)
|
|
return update_iter_mod(iter, pos);
|
|
|
|
/* If we're not on the desired position, reset to new position. */
|
|
if (pos != iter->pos)
|
|
reset_iter(iter, pos);
|
|
|
|
iter->nameoff += get_ksymbol_core(iter);
|
|
iter->pos++;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void *s_next(struct seq_file *m, void *p, loff_t *pos)
|
|
{
|
|
(*pos)++;
|
|
|
|
if (!update_iter(m->private, *pos))
|
|
return NULL;
|
|
return p;
|
|
}
|
|
|
|
static void *s_start(struct seq_file *m, loff_t *pos)
|
|
{
|
|
if (!update_iter(m->private, *pos))
|
|
return NULL;
|
|
return m->private;
|
|
}
|
|
|
|
static void s_stop(struct seq_file *m, void *p)
|
|
{
|
|
}
|
|
|
|
static int s_show(struct seq_file *m, void *p)
|
|
{
|
|
void *value;
|
|
struct kallsym_iter *iter = m->private;
|
|
|
|
/* Some debugging symbols have no name. Ignore them. */
|
|
if (!iter->name[0])
|
|
return 0;
|
|
|
|
value = iter->show_value ? (void *)iter->value : NULL;
|
|
|
|
if (iter->module_name[0]) {
|
|
char type;
|
|
|
|
/*
|
|
* Label it "global" if it is exported,
|
|
* "local" if not exported.
|
|
*/
|
|
type = iter->exported ? toupper(iter->type) :
|
|
tolower(iter->type);
|
|
seq_printf(m, "%px %c %s\t[%s]\n", value,
|
|
type, iter->name, iter->module_name);
|
|
} else
|
|
seq_printf(m, "%px %c %s\n", value,
|
|
iter->type, iter->name);
|
|
return 0;
|
|
}
|
|
|
|
static const struct seq_operations kallsyms_op = {
|
|
.start = s_start,
|
|
.next = s_next,
|
|
.stop = s_stop,
|
|
.show = s_show
|
|
};
|
|
|
|
#ifdef CONFIG_BPF_SYSCALL
|
|
|
|
struct bpf_iter__ksym {
|
|
__bpf_md_ptr(struct bpf_iter_meta *, meta);
|
|
__bpf_md_ptr(struct kallsym_iter *, ksym);
|
|
};
|
|
|
|
static int ksym_prog_seq_show(struct seq_file *m, bool in_stop)
|
|
{
|
|
struct bpf_iter__ksym ctx;
|
|
struct bpf_iter_meta meta;
|
|
struct bpf_prog *prog;
|
|
|
|
meta.seq = m;
|
|
prog = bpf_iter_get_info(&meta, in_stop);
|
|
if (!prog)
|
|
return 0;
|
|
|
|
ctx.meta = &meta;
|
|
ctx.ksym = m ? m->private : NULL;
|
|
return bpf_iter_run_prog(prog, &ctx);
|
|
}
|
|
|
|
static int bpf_iter_ksym_seq_show(struct seq_file *m, void *p)
|
|
{
|
|
return ksym_prog_seq_show(m, false);
|
|
}
|
|
|
|
static void bpf_iter_ksym_seq_stop(struct seq_file *m, void *p)
|
|
{
|
|
if (!p)
|
|
(void) ksym_prog_seq_show(m, true);
|
|
else
|
|
s_stop(m, p);
|
|
}
|
|
|
|
static const struct seq_operations bpf_iter_ksym_ops = {
|
|
.start = s_start,
|
|
.next = s_next,
|
|
.stop = bpf_iter_ksym_seq_stop,
|
|
.show = bpf_iter_ksym_seq_show,
|
|
};
|
|
|
|
static int bpf_iter_ksym_init(void *priv_data, struct bpf_iter_aux_info *aux)
|
|
{
|
|
struct kallsym_iter *iter = priv_data;
|
|
|
|
reset_iter(iter, 0);
|
|
|
|
/* cache here as in kallsyms_open() case; use current process
|
|
* credentials to tell BPF iterators if values should be shown.
|
|
*/
|
|
iter->show_value = kallsyms_show_value(current_cred());
|
|
|
|
return 0;
|
|
}
|
|
|
|
DEFINE_BPF_ITER_FUNC(ksym, struct bpf_iter_meta *meta, struct kallsym_iter *ksym)
|
|
|
|
static const struct bpf_iter_seq_info ksym_iter_seq_info = {
|
|
.seq_ops = &bpf_iter_ksym_ops,
|
|
.init_seq_private = bpf_iter_ksym_init,
|
|
.fini_seq_private = NULL,
|
|
.seq_priv_size = sizeof(struct kallsym_iter),
|
|
};
|
|
|
|
static struct bpf_iter_reg ksym_iter_reg_info = {
|
|
.target = "ksym",
|
|
.feature = BPF_ITER_RESCHED,
|
|
.ctx_arg_info_size = 1,
|
|
.ctx_arg_info = {
|
|
{ offsetof(struct bpf_iter__ksym, ksym),
|
|
PTR_TO_BTF_ID_OR_NULL },
|
|
},
|
|
.seq_info = &ksym_iter_seq_info,
|
|
};
|
|
|
|
BTF_ID_LIST(btf_ksym_iter_id)
|
|
BTF_ID(struct, kallsym_iter)
|
|
|
|
static int __init bpf_ksym_iter_register(void)
|
|
{
|
|
ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
|
|
return bpf_iter_reg_target(&ksym_iter_reg_info);
|
|
}
|
|
|
|
late_initcall(bpf_ksym_iter_register);
|
|
|
|
#endif /* CONFIG_BPF_SYSCALL */
|
|
|
|
static inline int kallsyms_for_perf(void)
|
|
{
|
|
#ifdef CONFIG_PERF_EVENTS
|
|
extern int sysctl_perf_event_paranoid;
|
|
if (sysctl_perf_event_paranoid <= 1)
|
|
return 1;
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We show kallsyms information even to normal users if we've enabled
|
|
* kernel profiling and are explicitly not paranoid (so kptr_restrict
|
|
* is clear, and sysctl_perf_event_paranoid isn't set).
|
|
*
|
|
* Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to
|
|
* block even that).
|
|
*/
|
|
bool kallsyms_show_value(const struct cred *cred)
|
|
{
|
|
switch (kptr_restrict) {
|
|
case 0:
|
|
if (kallsyms_for_perf())
|
|
return true;
|
|
fallthrough;
|
|
case 1:
|
|
if (security_capable(cred, &init_user_ns, CAP_SYSLOG,
|
|
CAP_OPT_NOAUDIT) == 0)
|
|
return true;
|
|
fallthrough;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static int kallsyms_open(struct inode *inode, struct file *file)
|
|
{
|
|
/*
|
|
* We keep iterator in m->private, since normal case is to
|
|
* s_start from where we left off, so we avoid doing
|
|
* using get_symbol_offset for every symbol.
|
|
*/
|
|
struct kallsym_iter *iter;
|
|
iter = __seq_open_private(file, &kallsyms_op, sizeof(*iter));
|
|
if (!iter)
|
|
return -ENOMEM;
|
|
reset_iter(iter, 0);
|
|
|
|
/*
|
|
* Instead of checking this on every s_show() call, cache
|
|
* the result here at open time.
|
|
*/
|
|
iter->show_value = kallsyms_show_value(file->f_cred);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_KGDB_KDB
|
|
const char *kdb_walk_kallsyms(loff_t *pos)
|
|
{
|
|
static struct kallsym_iter kdb_walk_kallsyms_iter;
|
|
if (*pos == 0) {
|
|
memset(&kdb_walk_kallsyms_iter, 0,
|
|
sizeof(kdb_walk_kallsyms_iter));
|
|
reset_iter(&kdb_walk_kallsyms_iter, 0);
|
|
}
|
|
while (1) {
|
|
if (!update_iter(&kdb_walk_kallsyms_iter, *pos))
|
|
return NULL;
|
|
++*pos;
|
|
/* Some debugging symbols have no name. Ignore them. */
|
|
if (kdb_walk_kallsyms_iter.name[0])
|
|
return kdb_walk_kallsyms_iter.name;
|
|
}
|
|
}
|
|
#endif /* CONFIG_KGDB_KDB */
|
|
|
|
static const struct proc_ops kallsyms_proc_ops = {
|
|
.proc_open = kallsyms_open,
|
|
.proc_read = seq_read,
|
|
.proc_lseek = seq_lseek,
|
|
.proc_release = seq_release_private,
|
|
};
|
|
|
|
static int __init kallsyms_init(void)
|
|
{
|
|
proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
|
|
return 0;
|
|
}
|
|
device_initcall(kallsyms_init);
|