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bpf: Move stack_map_get_build_id into lib
Moving stack_map_get_build_id into lib with declaration in linux/buildid.h header: int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id); This function returns build id for given struct vm_area_struct. There is no functional change to stack_map_get_build_id function. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20210114134044.1418404-2-jolsa@kernel.org
This commit is contained in:
Jiri Olsa
Alexei Starovoitov
parent
7064a7341a
commit
bd7525dacd
11
include/linux/buildid.h
Normal file
11
include/linux/buildid.h
Normal file
@ -0,0 +1,11 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_BUILDID_H
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#define _LINUX_BUILDID_H
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#include <linux/mm_types.h>
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#define BUILD_ID_SIZE_MAX 20
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int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id);
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#endif
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@ -7,10 +7,9 @@
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#include <linux/kernel.h>
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#include <linux/stacktrace.h>
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#include <linux/perf_event.h>
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#include <linux/elf.h>
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#include <linux/pagemap.h>
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#include <linux/irq_work.h>
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#include <linux/btf_ids.h>
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#include <linux/buildid.h>
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#include "percpu_freelist.h"
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#define STACK_CREATE_FLAG_MASK \
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@ -143,140 +142,6 @@ free_smap:
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return ERR_PTR(err);
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}
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#define BPF_BUILD_ID 3
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/*
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* Parse build id from the note segment. This logic can be shared between
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* 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are
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* identical.
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*/
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static inline int stack_map_parse_build_id(void *page_addr,
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unsigned char *build_id,
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void *note_start,
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Elf32_Word note_size)
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{
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Elf32_Word note_offs = 0, new_offs;
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/* check for overflow */
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if (note_start < page_addr || note_start + note_size < note_start)
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return -EINVAL;
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/* only supports note that fits in the first page */
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if (note_start + note_size > page_addr + PAGE_SIZE)
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return -EINVAL;
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while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
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Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
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if (nhdr->n_type == BPF_BUILD_ID &&
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nhdr->n_namesz == sizeof("GNU") &&
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nhdr->n_descsz > 0 &&
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nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
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memcpy(build_id,
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note_start + note_offs +
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ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr),
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nhdr->n_descsz);
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memset(build_id + nhdr->n_descsz, 0,
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BPF_BUILD_ID_SIZE - nhdr->n_descsz);
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return 0;
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}
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new_offs = note_offs + sizeof(Elf32_Nhdr) +
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ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
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if (new_offs <= note_offs) /* overflow */
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break;
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note_offs = new_offs;
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}
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return -EINVAL;
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}
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/* Parse build ID from 32-bit ELF */
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static int stack_map_get_build_id_32(void *page_addr,
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unsigned char *build_id)
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{
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Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr;
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Elf32_Phdr *phdr;
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int i;
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/* only supports phdr that fits in one page */
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if (ehdr->e_phnum >
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(PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
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return -EINVAL;
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phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr));
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for (i = 0; i < ehdr->e_phnum; ++i) {
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if (phdr[i].p_type == PT_NOTE &&
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!stack_map_parse_build_id(page_addr, build_id,
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page_addr + phdr[i].p_offset,
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phdr[i].p_filesz))
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return 0;
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}
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return -EINVAL;
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}
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/* Parse build ID from 64-bit ELF */
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static int stack_map_get_build_id_64(void *page_addr,
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unsigned char *build_id)
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{
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Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr;
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Elf64_Phdr *phdr;
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int i;
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/* only supports phdr that fits in one page */
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if (ehdr->e_phnum >
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(PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))
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return -EINVAL;
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phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr));
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for (i = 0; i < ehdr->e_phnum; ++i) {
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if (phdr[i].p_type == PT_NOTE &&
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!stack_map_parse_build_id(page_addr, build_id,
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page_addr + phdr[i].p_offset,
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phdr[i].p_filesz))
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return 0;
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}
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return -EINVAL;
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}
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/* Parse build ID of ELF file mapped to vma */
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static int stack_map_get_build_id(struct vm_area_struct *vma,
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unsigned char *build_id)
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{
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Elf32_Ehdr *ehdr;
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struct page *page;
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void *page_addr;
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int ret;
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/* only works for page backed storage */
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if (!vma->vm_file)
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return -EINVAL;
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page = find_get_page(vma->vm_file->f_mapping, 0);
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if (!page)
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return -EFAULT; /* page not mapped */
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ret = -EINVAL;
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page_addr = kmap_atomic(page);
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ehdr = (Elf32_Ehdr *)page_addr;
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/* compare magic x7f "ELF" */
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if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
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goto out;
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/* only support executable file and shared object file */
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if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
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goto out;
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if (ehdr->e_ident[EI_CLASS] == ELFCLASS32)
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ret = stack_map_get_build_id_32(page_addr, build_id);
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else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64)
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ret = stack_map_get_build_id_64(page_addr, build_id);
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out:
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kunmap_atomic(page_addr);
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put_page(page);
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return ret;
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}
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static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
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u64 *ips, u32 trace_nr, bool user)
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{
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@ -317,18 +182,18 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
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for (i = 0; i < trace_nr; i++) {
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id_offs[i].status = BPF_STACK_BUILD_ID_IP;
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id_offs[i].ip = ips[i];
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memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE);
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memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
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}
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return;
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}
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for (i = 0; i < trace_nr; i++) {
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vma = find_vma(current->mm, ips[i]);
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if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) {
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if (!vma || build_id_parse(vma, id_offs[i].build_id)) {
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/* per entry fall back to ips */
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id_offs[i].status = BPF_STACK_BUILD_ID_IP;
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id_offs[i].ip = ips[i];
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memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE);
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memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
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continue;
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}
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id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]
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@ -36,7 +36,8 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
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flex_proportions.o ratelimit.o show_mem.o \
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is_single_threaded.o plist.o decompress.o kobject_uevent.o \
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earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
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nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o
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nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o \
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buildid.o
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lib-$(CONFIG_PRINTK) += dump_stack.o
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lib-$(CONFIG_SMP) += cpumask.o
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136
lib/buildid.c
Normal file
136
lib/buildid.c
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@ -0,0 +1,136 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/buildid.h>
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#include <linux/elf.h>
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#include <linux/pagemap.h>
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#define BUILD_ID 3
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/*
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* Parse build id from the note segment. This logic can be shared between
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* 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are
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* identical.
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*/
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static inline int parse_build_id(void *page_addr,
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unsigned char *build_id,
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void *note_start,
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Elf32_Word note_size)
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{
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Elf32_Word note_offs = 0, new_offs;
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/* check for overflow */
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if (note_start < page_addr || note_start + note_size < note_start)
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return -EINVAL;
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/* only supports note that fits in the first page */
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if (note_start + note_size > page_addr + PAGE_SIZE)
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return -EINVAL;
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while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
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Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
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if (nhdr->n_type == BUILD_ID &&
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nhdr->n_namesz == sizeof("GNU") &&
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nhdr->n_descsz > 0 &&
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nhdr->n_descsz <= BUILD_ID_SIZE_MAX) {
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memcpy(build_id,
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note_start + note_offs +
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ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr),
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nhdr->n_descsz);
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memset(build_id + nhdr->n_descsz, 0,
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BUILD_ID_SIZE_MAX - nhdr->n_descsz);
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return 0;
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}
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new_offs = note_offs + sizeof(Elf32_Nhdr) +
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ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
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if (new_offs <= note_offs) /* overflow */
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break;
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note_offs = new_offs;
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}
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return -EINVAL;
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}
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/* Parse build ID from 32-bit ELF */
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static int get_build_id_32(void *page_addr, unsigned char *build_id)
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{
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Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr;
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Elf32_Phdr *phdr;
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int i;
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/* only supports phdr that fits in one page */
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if (ehdr->e_phnum >
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(PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
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return -EINVAL;
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phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr));
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for (i = 0; i < ehdr->e_phnum; ++i) {
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if (phdr[i].p_type == PT_NOTE &&
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!parse_build_id(page_addr, build_id,
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page_addr + phdr[i].p_offset,
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phdr[i].p_filesz))
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return 0;
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}
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return -EINVAL;
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}
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/* Parse build ID from 64-bit ELF */
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static int get_build_id_64(void *page_addr, unsigned char *build_id)
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{
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Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr;
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Elf64_Phdr *phdr;
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int i;
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/* only supports phdr that fits in one page */
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if (ehdr->e_phnum >
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(PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))
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return -EINVAL;
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phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr));
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for (i = 0; i < ehdr->e_phnum; ++i) {
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if (phdr[i].p_type == PT_NOTE &&
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!parse_build_id(page_addr, build_id,
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page_addr + phdr[i].p_offset,
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phdr[i].p_filesz))
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return 0;
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}
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return -EINVAL;
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}
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/* Parse build ID of ELF file mapped to vma */
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int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id)
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{
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Elf32_Ehdr *ehdr;
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struct page *page;
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void *page_addr;
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int ret;
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/* only works for page backed storage */
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if (!vma->vm_file)
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return -EINVAL;
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page = find_get_page(vma->vm_file->f_mapping, 0);
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if (!page)
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return -EFAULT; /* page not mapped */
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ret = -EINVAL;
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page_addr = kmap_atomic(page);
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ehdr = (Elf32_Ehdr *)page_addr;
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/* compare magic x7f "ELF" */
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if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
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goto out;
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/* only support executable file and shared object file */
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if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
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goto out;
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if (ehdr->e_ident[EI_CLASS] == ELFCLASS32)
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ret = get_build_id_32(page_addr, build_id);
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else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64)
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ret = get_build_id_64(page_addr, build_id);
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out:
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kunmap_atomic(page_addr);
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put_page(page);
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return ret;
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}
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