HardenedBSD/usr.sbin/kldxref/ef.h
John Baldwin 785600d0fb kldxref: Properly handle reading strings near the end of an ELF file
If a string is at or near the end of an input file and the amount of
remaining data in the file is smaller than the maximum string size,
the pread(2) system call would return a short read which is treated as
an error.  Instead, add a new helper function for reading a string
which permits short reads so long as the data read from the file
contains a terminated string.

Reported by:	jrtc27
Reviewed by:	jrtc27
Sponsored by:	University of Cambridge, Google, Inc.
Differential Revision:	https://reviews.freebsd.org/D44419
2024-03-18 17:01:23 -07:00

316 lines
10 KiB
C

/*-
* SPDX-License-Identifier: BSD-4-Clause
*
* Copyright (c) 2000, Boris Popov
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Boris Popov.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _EF_H_
#define _EF_H_
#include <sys/linker_set.h>
#include <stdbool.h>
#define EF_CLOSE(ef) \
(ef)->ef_ops->close((ef)->ef_ef)
#define EF_SEG_READ_REL(ef, address, len, dest) \
(ef)->ef_ops->seg_read_rel((ef)->ef_ef, address, len, dest)
#define EF_SEG_READ_STRING(ef, address, len, dest) \
(ef)->ef_ops->seg_read_string((ef)->ef_ef, address, len, dest)
#define EF_SYMADDR(ef, symidx) \
(ef)->ef_ops->symaddr((ef)->ef_ef, symidx)
#define EF_LOOKUP_SET(ef, name, startp, stopp, countp) \
(ef)->ef_ops->lookup_set((ef)->ef_ef, name, startp, stopp, countp)
/* XXX, should have a different name. */
typedef struct ef_file *elf_file_t;
/* FreeBSD's headers define additional typedef's for ELF structures. */
typedef Elf64_Size GElf_Size;
typedef Elf64_Hashelt GElf_Hashelt;
struct elf_file;
struct elf_file_ops {
void (*close)(elf_file_t ef);
int (*seg_read_rel)(elf_file_t ef, GElf_Addr address, size_t len,
void *dest);
int (*seg_read_string)(elf_file_t ef, GElf_Addr address, size_t len,
char *dest);
GElf_Addr (*symaddr)(elf_file_t ef, GElf_Size symidx);
int (*lookup_set)(elf_file_t ef, const char *name, GElf_Addr *startp,
GElf_Addr *stopp, long *countp);
};
typedef int (elf_reloc_t)(struct elf_file *ef, const void *reldata,
Elf_Type reltype, GElf_Addr relbase, GElf_Addr dataoff, size_t len,
void *dest);
struct elf_reloc_data {
unsigned char class;
unsigned char data;
GElf_Half machine;
elf_reloc_t *reloc;
};
#define ELF_RELOC(_class, _data, _machine, _reloc) \
static struct elf_reloc_data __CONCAT(elf_reloc_data_, __LINE__) = { \
.class = (_class), \
.data = (_data), \
.machine = (_machine), \
.reloc = (_reloc) \
}; \
DATA_SET(elf_reloc, __CONCAT(elf_reloc_data_, __LINE__))
struct elf_file {
elf_file_t ef_ef;
struct elf_file_ops *ef_ops;
const char *ef_filename;
Elf *ef_elf;
elf_reloc_t *ef_reloc;
GElf_Ehdr ef_hdr;
size_t ef_pointer_size;
int ef_fd;
};
#define elf_machine(ef) ((ef)->ef_hdr.e_machine)
#define elf_class(ef) ((ef)->ef_hdr.e_ident[EI_CLASS])
#define elf_encoding(ef) ((ef)->ef_hdr.e_ident[EI_DATA])
/*
* "Generic" versions of module metadata structures.
*/
struct Gmod_depend {
int md_ver_minimum;
int md_ver_preferred;
int md_ver_maximum;
};
struct Gmod_version {
int mv_version;
};
struct Gmod_metadata {
int md_version; /* structure version MDTV_* */
int md_type; /* type of entry MDT_* */
GElf_Addr md_data; /* specific data */
GElf_Addr md_cval; /* common string label */
};
struct Gmod_pnp_match_info
{
GElf_Addr descr; /* Description of the table */
GElf_Addr bus; /* Name of the bus for this table */
GElf_Addr table; /* Pointer to pnp table */
int entry_len; /* Length of each entry in the table (may be */
/* longer than descr describes). */
int num_entry; /* Number of entries in the table */
};
__BEGIN_DECLS
/*
* Attempt to parse an open ELF file as either an executable or DSO
* (ef_open) or an object file (ef_obj_open). On success, these
* routines initialize the 'ef_ef' and 'ef_ops' members of 'ef'.
*/
int ef_open(struct elf_file *ef, int verbose);
int ef_obj_open(struct elf_file *ef, int verbose);
/*
* Direct operations on an ELF file regardless of type. Many of these
* use libelf.
*/
/*
* Open an ELF file with libelf. Populates fields other than ef_ef
* and ef_ops in '*efile'.
*/
int elf_open_file(struct elf_file *efile, const char *filename,
int verbose);
/* Close an ELF file. */
void elf_close_file(struct elf_file *efile);
/* Is an ELF file the same architecture as hdr? */
bool elf_compatible(struct elf_file *efile, const GElf_Ehdr *hdr);
/* The size of a single object of 'type'. */
size_t elf_object_size(struct elf_file *efile, Elf_Type type);
/* The size of a pointer in architecture of 'efile'. */
size_t elf_pointer_size(struct elf_file *efile);
/*
* Read and convert an array of a data type from an ELF file. This is
* a wrapper around gelf_xlatetom() which reads an array of raw ELF
* objects from the file and converts them into host structures using
* native endianness. The data is returned in a dynamically-allocated
* buffer.
*/
int elf_read_data(struct elf_file *efile, Elf_Type type, off_t offset,
size_t len, void **out);
/* Reads "raw" data from an ELF file without any translation. */
int elf_read_raw_data(struct elf_file *efile, off_t offset, void *dst,
size_t len);
/*
* A wrapper around elf_read_raw_data which returns the data in a
* dynamically-allocated buffer.
*/
int elf_read_raw_data_alloc(struct elf_file *efile, off_t offset,
size_t len, void **out);
/* Reads a single string at the given offset from an ELF file. */
int elf_read_raw_string(struct elf_file *efile, off_t offset, char *dst,
size_t len);
/*
* Read relocated data from an ELF file and return it in a
* dynamically-allocated buffer. Note that no translation
* (byte-swapping for endianness, 32-vs-64) is performed on the
* returned data, but any ELF relocations which affect the contents
* are applied to the returned data. The address parameter gives the
* address of the data buffer if the ELF file were loaded into memory
* rather than a direct file offset.
*/
int elf_read_relocated_data(struct elf_file *efile, GElf_Addr address,
size_t len, void **buf);
/*
* Read the program headers from an ELF file and return them in a
* dynamically-allocated array of GElf_Phdr objects.
*/
int elf_read_phdrs(struct elf_file *efile, size_t *nphdrp,
GElf_Phdr **phdrp);
/*
* Read the section headers from an ELF file and return them in a
* dynamically-allocated array of GElf_Shdr objects.
*/
int elf_read_shdrs(struct elf_file *efile, size_t *nshdrp,
GElf_Shdr **shdrp);
/*
* Read the dynamic table from a section of an ELF file into a
* dynamically-allocated array of GElf_Dyn objects.
*/
int elf_read_dynamic(struct elf_file *efile, int section_index, size_t *ndynp,
GElf_Dyn **dynp);
/*
* Read a symbol table from a section of an ELF file into a
* dynamically-allocated array of GElf_Sym objects.
*/
int elf_read_symbols(struct elf_file *efile, int section_index,
size_t *nsymp, GElf_Sym **symp);
/*
* Read a string table described by a section header of an ELF file
* into a dynamically-allocated buffer.
*/
int elf_read_string_table(struct elf_file *efile, const GElf_Shdr *shdr,
long *strcnt, char **strtab);
/*
* Read a table of relocation objects from a section of an ELF file
* into a dynamically-allocated array of GElf_Rel objects.
*/
int elf_read_rel(struct elf_file *efile, int section_index, long *nrelp,
GElf_Rel **relp);
/*
* Read a table of relocation-with-addend objects from a section of an
* ELF file into a dynamically-allocated array of GElf_Rela objects.
*/
int elf_read_rela(struct elf_file *efile, int section_index, long *nrelap,
GElf_Rela **relap);
/*
* Read a string from an ELF file and return it in the provided
* buffer. If the string is longer than the buffer, this fails with
* EFAULT. The address parameter gives the address of the data buffer
* if the ELF file were loaded into memory rather than a direct file
* offset.
*/
int elf_read_string(struct elf_file *efile, GElf_Addr address, void *dst,
size_t len);
/* Return the address extracted from a target pointer stored at 'p'. */
GElf_Addr elf_address_from_pointer(struct elf_file *efile, const void *p);
/*
* Read a linker set and return an array of addresses extracted from the
* relocated pointers in the linker set.
*/
int elf_read_linker_set(struct elf_file *efile, const char *name,
GElf_Addr **buf, long *countp);
/*
* Read and convert a target 'struct mod_depend' into a host
* 'struct Gmod_depend'.
*/
int elf_read_mod_depend(struct elf_file *efile, GElf_Addr addr,
struct Gmod_depend *mdp);
/*
* Read and convert a target 'struct mod_version' into a host
* 'struct Gmod_version'.
*/
int elf_read_mod_version(struct elf_file *efile, GElf_Addr addr,
struct Gmod_version *mdv);
/*
* Read and convert a target 'struct mod_metadata' into a host
* 'struct Gmod_metadata'.
*/
int elf_read_mod_metadata(struct elf_file *efile, GElf_Addr addr,
struct Gmod_metadata *md);
/*
* Read and convert a target 'struct mod_pnp_match_info' into a host
* 'struct Gmod_pnp_match_info'.
*/
int elf_read_mod_pnp_match_info(struct elf_file *efile, GElf_Addr addr,
struct Gmod_pnp_match_info *pnp);
/*
* Apply relocations to the values obtained from the file. `relbase' is the
* target relocation address of the section, and `dataoff/len' is the region
* that is to be relocated, and has been copied to *dest
*/
int elf_reloc(struct elf_file *ef, const void *reldata, Elf_Type reltype,
GElf_Addr relbase, GElf_Addr dataoff, size_t len, void *dest);
__END_DECLS
#endif /* _EF_H_*/