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linux/fs/binfmt_elf_fdpic.c
Christian Brauner 2a010c4128 fs: don't block i_writecount during exec 
Back in 2021 we already discussed removing deny_write_access() for
executables. Back then I was hesistant because I thought that this might
cause issues in userspace. But even back then I had started taking some
notes on what could potentially depend on this and I didn't come up with
a lot so I've changed my mind and I would like to try this.

Here are some of the notes that I took:

(1) The deny_write_access() mechanism is causing really pointless issues
    such as [1]. If a thread in a thread-group opens a file writable,
    then writes some stuff, then closing the file descriptor and then
    calling execve() they can fail the execve() with ETXTBUSY because
    another thread in the thread-group could have concurrently called
    fork(). Multi-threaded libraries such as go suffer from this.

(2) There are userspace attacks that rely on overwriting the binary of a
    running process. These attacks are _mitigated_ but _not at all
    prevented_ from ocurring by the deny_write_access() mechanism.

    I'll go over some details. The clearest example of such attacks was
    the attack against runC in CVE-2019-5736 (cf. [3]).

    An attack could compromise the runC host binary from inside a
    _privileged_ runC container. The malicious binary could then be used
    to take over the host.

    (It is crucial to note that this attack is _not_ possible with
     unprivileged containers. IOW, the setup here is already insecure.)

    The attack can be made when attaching to a running container or when
    starting a container running a specially crafted image. For example,
    when runC attaches to a container the attacker can trick it into
    executing itself.

    This could be done by replacing the target binary inside the
    container with a custom binary pointing back at the runC binary
    itself. As an example, if the target binary was /bin/bash, this
    could be replaced with an executable script specifying the
    interpreter path #!/proc/self/exe.

    As such when /bin/bash is executed inside the container, instead the
    target of /proc/self/exe will be executed. That magic link will
    point to the runc binary on the host. The attacker can then proceed
    to write to the target of /proc/self/exe to try and overwrite the
    runC binary on the host.

    However, this will not succeed because of deny_write_access(). Now,
    one might think that this would prevent the attack but it doesn't.

    To overcome this, the attacker has multiple ways:
    * Open a file descriptor to /proc/self/exe using the O_PATH flag and
      then proceed to reopen the binary as O_WRONLY through
      /proc/self/fd/<nr> and try to write to it in a busy loop from a
      separate process. Ultimately it will succeed when the runC binary
      exits. After this the runC binary is compromised and can be used
      to attack other containers or the host itself.
    * Use a malicious shared library annotating a function in there with
      the constructor attribute making the malicious function run as an
      initializor. The malicious library will then open /proc/self/exe
      for creating a new entry under /proc/self/fd/<nr>. It'll then call
      exec to a) force runC to exit and b) hand the file descriptor off
      to a program that then reopens /proc/self/fd/<nr> for writing
      (which is now possible because runC has exited) and overwriting
      that binary.

    To sum up: the deny_write_access() mechanism doesn't prevent such
    attacks in insecure setups. It just makes them minimally harder.
    That's all.

    The only way back then to prevent this is to create a temporary copy
    of the calling binary itself when it starts or attaches to
    containers. So what I did back then for LXC (and Aleksa for runC)
    was to create an anonymous, in-memory file using the memfd_create()
    system call and to copy itself into the temporary in-memory file,
    which is then sealed to prevent further modifications. This sealed,
    in-memory file copy is then executed instead of the original on-disk
    binary.

    Any compromising write operations from a privileged container to the
    host binary will then write to the temporary in-memory binary and
    not to the host binary on-disk, preserving the integrity of the host
    binary. Also as the temporary, in-memory binary is sealed, writes to
    this will also fail.

    The point is that deny_write_access() is uselss to prevent these
    attacks.

(3) Denying write access to an inode because it's currently used in an
    exec path could easily be done on an LSM level. It might need an
    additional hook but that should be about it.

(4) The MAP_DENYWRITE flag for mmap() has been deprecated a long time
    ago so while we do protect the main executable the bigger portion of
    the things you'd think need protecting such as the shared libraries
    aren't. IOW, we let anyone happily overwrite shared libraries.

(5) We removed all remaining uses of VM_DENYWRITE in [2]. That means:
    (5.1) We removed the legacy uselib() protection for preventing
          overwriting of shared libraries. Nobody cared in 3 years.
    (5.2) We allow write access to the elf interpreter after exec
          completed treating it on a par with shared libraries.

Yes, someone in userspace could potentially be relying on this. It's not
completely out of the realm of possibility but let's find out if that's
actually the case and not guess.

Link: https://github.com/golang/go/issues/22315 [1]
Link: 49624efa65 ("Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux") [2]
Link: https://unit42.paloaltonetworks.com/breaking-docker-via-runc-explaining-cve-2019-5736 [3]
Link: https://lwn.net/Articles/866493
Link: https://github.com/golang/go/issues/22220
Link: 5bf8c0cf09/src/cmd/go/internal/work/buildid.go (L724)
Link: 5bf8c0cf09/src/cmd/go/internal/work/exec.go (L1493)
Link: 5bf8c0cf09/src/cmd/go/internal/script/cmds.go (L457)
Link: 5bf8c0cf09/src/cmd/go/internal/test/test.go (L1557)
Link: 5bf8c0cf09/src/os/exec/lp_linux_test.go (L61)
Link: https://github.com/buildkite/agent/pull/2736
Link: https://github.com/rust-lang/rust/issues/114554
Link: https://bugs.openjdk.org/browse/JDK-8068370
Link: https://github.com/dotnet/runtime/issues/58964
Link: https://lore.kernel.org/r/20240531-vfs-i_writecount-v1-1-a17bea7ee36b@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-03 15:52:10 +02:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* binfmt_elf_fdpic.c: FDPIC ELF binary format
*
* Copyright (C) 2003, 2004, 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* Derived from binfmt_elf.c
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/sched/coredump.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/cputime.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/binfmts.h>
#include <linux/string.h>
#include <linux/file.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/highmem.h>
#include <linux/highuid.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/init.h>
#include <linux/elf.h>
#include <linux/elf-fdpic.h>
#include <linux/elfcore.h>
#include <linux/coredump.h>
#include <linux/dax.h>
#include <linux/regset.h>
#include <linux/uaccess.h>
#include <asm/param.h>
typedef char *elf_caddr_t;
#if 0
#define kdebug(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdebug(fmt, ...) do {} while(0)
#endif
#if 0
#define kdcore(fmt, ...) printk("FDPIC "fmt"\n" ,##__VA_ARGS__ )
#else
#define kdcore(fmt, ...) do {} while(0)
#endif
MODULE_LICENSE("GPL");
static int load_elf_fdpic_binary(struct linux_binprm *);
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *, struct file *);
static int elf_fdpic_map_file(struct elf_fdpic_params *, struct file *,
struct mm_struct *, const char *);
static int create_elf_fdpic_tables(struct linux_binprm *, struct mm_struct *,
struct elf_fdpic_params *,
struct elf_fdpic_params *);
#ifndef CONFIG_MMU
static int elf_fdpic_map_file_constdisp_on_uclinux(struct elf_fdpic_params *,
struct file *,
struct mm_struct *);
#endif
static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *,
struct file *, struct mm_struct *);
#ifdef CONFIG_ELF_CORE
static int elf_fdpic_core_dump(struct coredump_params *cprm);
#endif
static struct linux_binfmt elf_fdpic_format = {
.module = THIS_MODULE,
.load_binary = load_elf_fdpic_binary,
#ifdef CONFIG_ELF_CORE
.core_dump = elf_fdpic_core_dump,
.min_coredump = ELF_EXEC_PAGESIZE,
#endif
};
static int __init init_elf_fdpic_binfmt(void)
{
register_binfmt(&elf_fdpic_format);
return 0;
}
static void __exit exit_elf_fdpic_binfmt(void)
{
unregister_binfmt(&elf_fdpic_format);
}
core_initcall(init_elf_fdpic_binfmt);
module_exit(exit_elf_fdpic_binfmt);
static int is_elf(struct elfhdr *hdr, struct file *file)
{
if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0)
return 0;
if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN)
return 0;
if (!elf_check_arch(hdr))
return 0;
if (!file->f_op->mmap)
return 0;
return 1;
}
#ifndef elf_check_fdpic
#define elf_check_fdpic(x) 0
#endif
#ifndef elf_check_const_displacement
#define elf_check_const_displacement(x) 0
#endif
static int is_constdisp(struct elfhdr *hdr)
{
if (!elf_check_fdpic(hdr))
return 1;
if (elf_check_const_displacement(hdr))
return 1;
return 0;
}
/*****************************************************************************/
/*
* read the program headers table into memory
*/
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,
struct file *file)
{
struct elf_phdr *phdr;
unsigned long size;
int retval, loop;
loff_t pos = params->hdr.e_phoff;
if (params->hdr.e_phentsize != sizeof(struct elf_phdr))
return -ENOMEM;
if (params->hdr.e_phnum > 65536U / sizeof(struct elf_phdr))
return -ENOMEM;
size = params->hdr.e_phnum * sizeof(struct elf_phdr);
params->phdrs = kmalloc(size, GFP_KERNEL);
if (!params->phdrs)
return -ENOMEM;
retval = kernel_read(file, params->phdrs, size, &pos);
if (unlikely(retval != size))
return retval < 0 ? retval : -ENOEXEC;
/* determine stack size for this binary */
phdr = params->phdrs;
for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
if (phdr->p_type != PT_GNU_STACK)
continue;
if (phdr->p_flags & PF_X)
params->flags |= ELF_FDPIC_FLAG_EXEC_STACK;
else
params->flags |= ELF_FDPIC_FLAG_NOEXEC_STACK;
params->stack_size = phdr->p_memsz;
break;
}
return 0;
}
/*****************************************************************************/
/*
* load an fdpic binary into various bits of memory
*/
static int load_elf_fdpic_binary(struct linux_binprm *bprm)
{
struct elf_fdpic_params exec_params, interp_params;
struct pt_regs *regs = current_pt_regs();
struct elf_phdr *phdr;
unsigned long stack_size, entryaddr;
#ifdef ELF_FDPIC_PLAT_INIT
unsigned long dynaddr;
#endif
#ifndef CONFIG_MMU
unsigned long stack_prot;
#endif
struct file *interpreter = NULL; /* to shut gcc up */
char *interpreter_name = NULL;
int executable_stack;
int retval, i;
loff_t pos;
kdebug("____ LOAD %d ____", current->pid);
memset(&exec_params, 0, sizeof(exec_params));
memset(&interp_params, 0, sizeof(interp_params));
exec_params.hdr = *(struct elfhdr *) bprm->buf;
exec_params.flags = ELF_FDPIC_FLAG_PRESENT | ELF_FDPIC_FLAG_EXECUTABLE;
/* check that this is a binary we know how to deal with */
retval = -ENOEXEC;
if (!is_elf(&exec_params.hdr, bprm->file))
goto error;
if (!elf_check_fdpic(&exec_params.hdr)) {
#ifdef CONFIG_MMU
/* binfmt_elf handles non-fdpic elf except on nommu */
goto error;
#else
/* nommu can only load ET_DYN (PIE) ELF */
if (exec_params.hdr.e_type != ET_DYN)
goto error;
#endif
}
/* read the program header table */
retval = elf_fdpic_fetch_phdrs(&exec_params, bprm->file);
if (retval < 0)
goto error;
/* scan for a program header that specifies an interpreter */
phdr = exec_params.phdrs;
for (i = 0; i < exec_params.hdr.e_phnum; i++, phdr++) {
switch (phdr->p_type) {
case PT_INTERP:
retval = -ENOMEM;
if (phdr->p_filesz > PATH_MAX)
goto error;
retval = -ENOENT;
if (phdr->p_filesz < 2)
goto error;
/* read the name of the interpreter into memory */
interpreter_name = kmalloc(phdr->p_filesz, GFP_KERNEL);
if (!interpreter_name)
goto error;
pos = phdr->p_offset;
retval = kernel_read(bprm->file, interpreter_name,
phdr->p_filesz, &pos);
if (unlikely(retval != phdr->p_filesz)) {
if (retval >= 0)
retval = -ENOEXEC;
goto error;
}
retval = -ENOENT;
if (interpreter_name[phdr->p_filesz - 1] != '\0')
goto error;
kdebug("Using ELF interpreter %s", interpreter_name);
/* replace the program with the interpreter */
interpreter = open_exec(interpreter_name);
retval = PTR_ERR(interpreter);
if (IS_ERR(interpreter)) {
interpreter = NULL;
goto error;
}
/*
* If the binary is not readable then enforce
* mm->dumpable = 0 regardless of the interpreter's
* permissions.
*/
would_dump(bprm, interpreter);
pos = 0;
retval = kernel_read(interpreter, bprm->buf,
BINPRM_BUF_SIZE, &pos);
if (unlikely(retval != BINPRM_BUF_SIZE)) {
if (retval >= 0)
retval = -ENOEXEC;
goto error;
}
interp_params.hdr = *((struct elfhdr *) bprm->buf);
break;
case PT_LOAD:
#ifdef CONFIG_MMU
if (exec_params.load_addr == 0)
exec_params.load_addr = phdr->p_vaddr;
#endif
break;
}
}
if (is_constdisp(&exec_params.hdr))
exec_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;
/* perform insanity checks on the interpreter */
if (interpreter_name) {
retval = -ELIBBAD;
if (!is_elf(&interp_params.hdr, interpreter))
goto error;
interp_params.flags = ELF_FDPIC_FLAG_PRESENT;
/* read the interpreter's program header table */
retval = elf_fdpic_fetch_phdrs(&interp_params, interpreter);
if (retval < 0)
goto error;
}
stack_size = exec_params.stack_size;
if (exec_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
executable_stack = EXSTACK_ENABLE_X;
else if (exec_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK)
executable_stack = EXSTACK_DISABLE_X;
else
executable_stack = EXSTACK_DEFAULT;
if (stack_size == 0 && interp_params.flags & ELF_FDPIC_FLAG_PRESENT) {
stack_size = interp_params.stack_size;
if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
executable_stack = EXSTACK_ENABLE_X;
else if (interp_params.flags & ELF_FDPIC_FLAG_NOEXEC_STACK)
executable_stack = EXSTACK_DISABLE_X;
else
executable_stack = EXSTACK_DEFAULT;
}
retval = -ENOEXEC;
if (stack_size == 0)
stack_size = 131072UL; /* same as exec.c's default commit */
if (is_constdisp(&interp_params.hdr))
interp_params.flags |= ELF_FDPIC_FLAG_CONSTDISP;
/* flush all traces of the currently running executable */
retval = begin_new_exec(bprm);
if (retval)
goto error;
/* there's now no turning back... the old userspace image is dead,
* defunct, deceased, etc.
*/
SET_PERSONALITY(exec_params.hdr);
if (elf_check_fdpic(&exec_params.hdr))
current->personality |= PER_LINUX_FDPIC;
if (elf_read_implies_exec(&exec_params.hdr, executable_stack))
current->personality |= READ_IMPLIES_EXEC;
setup_new_exec(bprm);
set_binfmt(&elf_fdpic_format);
current->mm->start_code = 0;
current->mm->end_code = 0;
current->mm->start_stack = 0;
current->mm->start_data = 0;
current->mm->end_data = 0;
current->mm->context.exec_fdpic_loadmap = 0;
current->mm->context.interp_fdpic_loadmap = 0;
#ifdef CONFIG_MMU
elf_fdpic_arch_lay_out_mm(&exec_params,
&interp_params,
&current->mm->start_stack,
&current->mm->start_brk);
retval = setup_arg_pages(bprm, current->mm->start_stack,
executable_stack);
if (retval < 0)
goto error;
#ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES
retval = arch_setup_additional_pages(bprm, !!interpreter_name);
if (retval < 0)
goto error;
#endif
#endif
/* load the executable and interpreter into memory */
retval = elf_fdpic_map_file(&exec_params, bprm->file, current->mm,
"executable");
if (retval < 0)
goto error;
if (interpreter_name) {
retval = elf_fdpic_map_file(&interp_params, interpreter,
current->mm, "interpreter");
if (retval < 0) {
printk(KERN_ERR "Unable to load interpreter\n");
goto error;
}
fput(interpreter);
interpreter = NULL;
}
#ifdef CONFIG_MMU
if (!current->mm->start_brk)
current->mm->start_brk = current->mm->end_data;
current->mm->brk = current->mm->start_brk =
PAGE_ALIGN(current->mm->start_brk);
#else
/* create a stack area and zero-size brk area */
stack_size = (stack_size + PAGE_SIZE - 1) & PAGE_MASK;
if (stack_size < PAGE_SIZE * 2)
stack_size = PAGE_SIZE * 2;
stack_prot = PROT_READ | PROT_WRITE;
if (executable_stack == EXSTACK_ENABLE_X ||
(executable_stack == EXSTACK_DEFAULT && VM_STACK_FLAGS & VM_EXEC))
stack_prot |= PROT_EXEC;
current->mm->start_brk = vm_mmap(NULL, 0, stack_size, stack_prot,
MAP_PRIVATE | MAP_ANONYMOUS |
MAP_UNINITIALIZED | MAP_GROWSDOWN,
0);
if (IS_ERR_VALUE(current->mm->start_brk)) {
retval = current->mm->start_brk;
current->mm->start_brk = 0;
goto error;
}
current->mm->brk = current->mm->start_brk;
current->mm->context.end_brk = current->mm->start_brk;
current->mm->start_stack = current->mm->start_brk + stack_size;
#endif
retval = create_elf_fdpic_tables(bprm, current->mm, &exec_params,
&interp_params);
if (retval < 0)
goto error;
kdebug("- start_code %lx", current->mm->start_code);
kdebug("- end_code %lx", current->mm->end_code);
kdebug("- start_data %lx", current->mm->start_data);
kdebug("- end_data %lx", current->mm->end_data);
kdebug("- start_brk %lx", current->mm->start_brk);
kdebug("- brk %lx", current->mm->brk);
kdebug("- start_stack %lx", current->mm->start_stack);
#ifdef ELF_FDPIC_PLAT_INIT
/*
* The ABI may specify that certain registers be set up in special
* ways (on i386 %edx is the address of a DT_FINI function, for
* example. This macro performs whatever initialization to
* the regs structure is required.
*/
dynaddr = interp_params.dynamic_addr ?: exec_params.dynamic_addr;
ELF_FDPIC_PLAT_INIT(regs, exec_params.map_addr, interp_params.map_addr,
dynaddr);
#endif
finalize_exec(bprm);
/* everything is now ready... get the userspace context ready to roll */
entryaddr = interp_params.entry_addr ?: exec_params.entry_addr;
start_thread(regs, entryaddr, current->mm->start_stack);
retval = 0;
error:
if (interpreter)
fput(interpreter);
kfree(interpreter_name);
kfree(exec_params.phdrs);
kfree(exec_params.loadmap);
kfree(interp_params.phdrs);
kfree(interp_params.loadmap);
return retval;
}
/*****************************************************************************/
#ifndef ELF_BASE_PLATFORM
/*
* AT_BASE_PLATFORM indicates the "real" hardware/microarchitecture.
* If the arch defines ELF_BASE_PLATFORM (in asm/elf.h), the value
* will be copied to the user stack in the same manner as AT_PLATFORM.
*/
#define ELF_BASE_PLATFORM NULL
#endif
/*
* present useful information to the program by shovelling it onto the new
* process's stack
*/
static int create_elf_fdpic_tables(struct linux_binprm *bprm,
struct mm_struct *mm,
struct elf_fdpic_params *exec_params,
struct elf_fdpic_params *interp_params)
{
const struct cred *cred = current_cred();
unsigned long sp, csp, nitems;
elf_caddr_t __user *argv, *envp;
size_t platform_len = 0, len;
char *k_platform, *k_base_platform;
char __user *u_platform, *u_base_platform, *p;
int loop;
unsigned long flags = 0;
int ei_index;
elf_addr_t *elf_info;
#ifdef CONFIG_MMU
/* In some cases (e.g. Hyper-Threading), we want to avoid L1 evictions
* by the processes running on the same package. One thing we can do is
* to shuffle the initial stack for them, so we give the architecture
* an opportunity to do so here.
*/
sp = arch_align_stack(bprm->p);
#else
sp = mm->start_stack;
/* stack the program arguments and environment */
if (transfer_args_to_stack(bprm, &sp) < 0)
return -EFAULT;
sp &= ~15;
#endif
/*
* If this architecture has a platform capability string, copy it
* to userspace. In some cases (Sparc), this info is impossible
* for userspace to get any other way, in others (i386) it is
* merely difficult.
*/
k_platform = ELF_PLATFORM;
u_platform = NULL;
if (k_platform) {
platform_len = strlen(k_platform) + 1;
sp -= platform_len;
u_platform = (char __user *) sp;
if (copy_to_user(u_platform, k_platform, platform_len) != 0)
return -EFAULT;
}
/*
* If this architecture has a "base" platform capability
* string, copy it to userspace.
*/
k_base_platform = ELF_BASE_PLATFORM;
u_base_platform = NULL;
if (k_base_platform) {
platform_len = strlen(k_base_platform) + 1;
sp -= platform_len;
u_base_platform = (char __user *) sp;
if (copy_to_user(u_base_platform, k_base_platform, platform_len) != 0)
return -EFAULT;
}
sp &= ~7UL;
/* stack the load map(s) */
len = sizeof(struct elf_fdpic_loadmap);
len += sizeof(struct elf_fdpic_loadseg) * exec_params->loadmap->nsegs;
sp = (sp - len) & ~7UL;
exec_params->map_addr = sp;
if (copy_to_user((void __user *) sp, exec_params->loadmap, len) != 0)
return -EFAULT;
current->mm->context.exec_fdpic_loadmap = (unsigned long) sp;
if (interp_params->loadmap) {
len = sizeof(struct elf_fdpic_loadmap);
len += sizeof(struct elf_fdpic_loadseg) *
interp_params->loadmap->nsegs;
sp = (sp - len) & ~7UL;
interp_params->map_addr = sp;
if (copy_to_user((void __user *) sp, interp_params->loadmap,
len) != 0)
return -EFAULT;
current->mm->context.interp_fdpic_loadmap = (unsigned long) sp;
}
/* force 16 byte _final_ alignment here for generality */
#define DLINFO_ITEMS 15
nitems = 1 + DLINFO_ITEMS + (k_platform ? 1 : 0) +
(k_base_platform ? 1 : 0) + AT_VECTOR_SIZE_ARCH;
if (bprm->have_execfd)
nitems++;
csp = sp;
sp -= nitems * 2 * sizeof(unsigned long);
sp -= (bprm->envc + 1) * sizeof(char *); /* envv[] */
sp -= (bprm->argc + 1) * sizeof(char *); /* argv[] */
sp -= 1 * sizeof(unsigned long); /* argc */
csp -= sp & 15UL;
sp -= sp & 15UL;
/* Create the ELF interpreter info */
elf_info = (elf_addr_t *)mm->saved_auxv;
/* update AT_VECTOR_SIZE_BASE if the number of NEW_AUX_ENT() changes */
#define NEW_AUX_ENT(id, val) \
do { \
*elf_info++ = id; \
*elf_info++ = val; \
} while (0)
#ifdef ARCH_DLINFO
/*
* ARCH_DLINFO must come first so PPC can do its special alignment of
* AUXV.
* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT() in
* ARCH_DLINFO changes
*/
ARCH_DLINFO;
#endif
NEW_AUX_ENT(AT_HWCAP, ELF_HWCAP);
#ifdef ELF_HWCAP2
NEW_AUX_ENT(AT_HWCAP2, ELF_HWCAP2);
#endif
NEW_AUX_ENT(AT_PAGESZ, PAGE_SIZE);
NEW_AUX_ENT(AT_CLKTCK, CLOCKS_PER_SEC);
NEW_AUX_ENT(AT_PHDR, exec_params->ph_addr);
NEW_AUX_ENT(AT_PHENT, sizeof(struct elf_phdr));
NEW_AUX_ENT(AT_PHNUM, exec_params->hdr.e_phnum);
NEW_AUX_ENT(AT_BASE, interp_params->elfhdr_addr);
if (bprm->interp_flags & BINPRM_FLAGS_PRESERVE_ARGV0)
flags |= AT_FLAGS_PRESERVE_ARGV0;
NEW_AUX_ENT(AT_FLAGS, flags);
NEW_AUX_ENT(AT_ENTRY, exec_params->entry_addr);
NEW_AUX_ENT(AT_UID, (elf_addr_t) from_kuid_munged(cred->user_ns, cred->uid));
NEW_AUX_ENT(AT_EUID, (elf_addr_t) from_kuid_munged(cred->user_ns, cred->euid));
NEW_AUX_ENT(AT_GID, (elf_addr_t) from_kgid_munged(cred->user_ns, cred->gid));
NEW_AUX_ENT(AT_EGID, (elf_addr_t) from_kgid_munged(cred->user_ns, cred->egid));
NEW_AUX_ENT(AT_SECURE, bprm->secureexec);
NEW_AUX_ENT(AT_EXECFN, bprm->exec);
if (k_platform)
NEW_AUX_ENT(AT_PLATFORM,
(elf_addr_t)(unsigned long)u_platform);
if (k_base_platform)
NEW_AUX_ENT(AT_BASE_PLATFORM,
(elf_addr_t)(unsigned long)u_base_platform);
if (bprm->have_execfd)
NEW_AUX_ENT(AT_EXECFD, bprm->execfd);
#undef NEW_AUX_ENT
/* AT_NULL is zero; clear the rest too */
memset(elf_info, 0, (char *)mm->saved_auxv +
sizeof(mm->saved_auxv) - (char *)elf_info);
/* And advance past the AT_NULL entry. */
elf_info += 2;
ei_index = elf_info - (elf_addr_t *)mm->saved_auxv;
csp -= ei_index * sizeof(elf_addr_t);
/* Put the elf_info on the stack in the right place. */
if (copy_to_user((void __user *)csp, mm->saved_auxv,
ei_index * sizeof(elf_addr_t)))
return -EFAULT;
/* allocate room for argv[] and envv[] */
csp -= (bprm->envc + 1) * sizeof(elf_caddr_t);
envp = (elf_caddr_t __user *) csp;
csp -= (bprm->argc + 1) * sizeof(elf_caddr_t);
argv = (elf_caddr_t __user *) csp;
/* stack argc */
csp -= sizeof(unsigned long);
if (put_user(bprm->argc, (unsigned long __user *) csp))
return -EFAULT;
BUG_ON(csp != sp);
/* fill in the argv[] array */
#ifdef CONFIG_MMU
current->mm->arg_start = bprm->p;
#else
current->mm->arg_start = current->mm->start_stack -
(MAX_ARG_PAGES * PAGE_SIZE - bprm->p);
#endif
p = (char __user *) current->mm->arg_start;
for (loop = bprm->argc; loop > 0; loop--) {
if (put_user((elf_caddr_t) p, argv++))
return -EFAULT;
len = strnlen_user(p, MAX_ARG_STRLEN);
if (!len || len > MAX_ARG_STRLEN)
return -EINVAL;
p += len;
}
if (put_user(NULL, argv))
return -EFAULT;
current->mm->arg_end = (unsigned long) p;
/* fill in the envv[] array */
current->mm->env_start = (unsigned long) p;
for (loop = bprm->envc; loop > 0; loop--) {
if (put_user((elf_caddr_t)(unsigned long) p, envp++))
return -EFAULT;
len = strnlen_user(p, MAX_ARG_STRLEN);
if (!len || len > MAX_ARG_STRLEN)
return -EINVAL;
p += len;
}
if (put_user(NULL, envp))
return -EFAULT;
current->mm->env_end = (unsigned long) p;
mm->start_stack = (unsigned long) sp;
return 0;
}
/*****************************************************************************/
/*
* load the appropriate binary image (executable or interpreter) into memory
* - we assume no MMU is available
* - if no other PIC bits are set in params->hdr->e_flags
* - we assume that the LOADable segments in the binary are independently relocatable
* - we assume R/O executable segments are shareable
* - else
* - we assume the loadable parts of the image to require fixed displacement
* - the image is not shareable
*/
static int elf_fdpic_map_file(struct elf_fdpic_params *params,
struct file *file,
struct mm_struct *mm,
const char *what)
{
struct elf_fdpic_loadmap *loadmap;
#ifdef CONFIG_MMU
struct elf_fdpic_loadseg *mseg;
unsigned long load_addr;
#endif
struct elf_fdpic_loadseg *seg;
struct elf_phdr *phdr;
unsigned nloads, tmp;
unsigned long stop;
int loop, ret;
/* allocate a load map table */
nloads = 0;
for (loop = 0; loop < params->hdr.e_phnum; loop++)
if (params->phdrs[loop].p_type == PT_LOAD)
nloads++;
if (nloads == 0)
return -ELIBBAD;
loadmap = kzalloc(struct_size(loadmap, segs, nloads), GFP_KERNEL);
if (!loadmap)
return -ENOMEM;
params->loadmap = loadmap;
loadmap->version = ELF_FDPIC_LOADMAP_VERSION;
loadmap->nsegs = nloads;
/* map the requested LOADs into the memory space */
switch (params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) {
case ELF_FDPIC_FLAG_CONSTDISP:
case ELF_FDPIC_FLAG_CONTIGUOUS:
#ifndef CONFIG_MMU
ret = elf_fdpic_map_file_constdisp_on_uclinux(params, file, mm);
if (ret < 0)
return ret;
break;
#endif
default:
ret = elf_fdpic_map_file_by_direct_mmap(params, file, mm);
if (ret < 0)
return ret;
break;
}
/* map the entry point */
if (params->hdr.e_entry) {
seg = loadmap->segs;
for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
if (params->hdr.e_entry >= seg->p_vaddr &&
params->hdr.e_entry < seg->p_vaddr + seg->p_memsz) {
params->entry_addr =
(params->hdr.e_entry - seg->p_vaddr) +
seg->addr;
break;
}
}
}
/* determine where the program header table has wound up if mapped */
stop = params->hdr.e_phoff;
stop += params->hdr.e_phnum * sizeof (struct elf_phdr);
phdr = params->phdrs;
for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
if (phdr->p_type != PT_LOAD)
continue;
if (phdr->p_offset > params->hdr.e_phoff ||
phdr->p_offset + phdr->p_filesz < stop)
continue;
seg = loadmap->segs;
for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
if (phdr->p_vaddr >= seg->p_vaddr &&
phdr->p_vaddr + phdr->p_filesz <=
seg->p_vaddr + seg->p_memsz) {
params->ph_addr =
(phdr->p_vaddr - seg->p_vaddr) +
seg->addr +
params->hdr.e_phoff - phdr->p_offset;
break;
}
}
break;
}
/* determine where the dynamic section has wound up if there is one */
phdr = params->phdrs;
for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
if (phdr->p_type != PT_DYNAMIC)
continue;
seg = loadmap->segs;
for (loop = loadmap->nsegs; loop > 0; loop--, seg++) {
if (phdr->p_vaddr >= seg->p_vaddr &&
phdr->p_vaddr + phdr->p_memsz <=
seg->p_vaddr + seg->p_memsz) {
Elf_Dyn __user *dyn;
Elf_Sword d_tag;
params->dynamic_addr =
(phdr->p_vaddr - seg->p_vaddr) +
seg->addr;
/* check the dynamic section contains at least
* one item, and that the last item is a NULL
* entry */
if (phdr->p_memsz == 0 ||
phdr->p_memsz % sizeof(Elf_Dyn) != 0)
goto dynamic_error;
tmp = phdr->p_memsz / sizeof(Elf_Dyn);
dyn = (Elf_Dyn __user *)params->dynamic_addr;
if (get_user(d_tag, &dyn[tmp - 1].d_tag) ||
d_tag != 0)
goto dynamic_error;
break;
}
}
break;
}
/* now elide adjacent segments in the load map on MMU linux
* - on uClinux the holes between may actually be filled with system
* stuff or stuff from other processes
*/
#ifdef CONFIG_MMU
nloads = loadmap->nsegs;
mseg = loadmap->segs;
seg = mseg + 1;
for (loop = 1; loop < nloads; loop++) {
/* see if we have a candidate for merging */
if (seg->p_vaddr - mseg->p_vaddr == seg->addr - mseg->addr) {
load_addr = PAGE_ALIGN(mseg->addr + mseg->p_memsz);
if (load_addr == (seg->addr & PAGE_MASK)) {
mseg->p_memsz +=
load_addr -
(mseg->addr + mseg->p_memsz);
mseg->p_memsz += seg->addr & ~PAGE_MASK;
mseg->p_memsz += seg->p_memsz;
loadmap->nsegs--;
continue;
}
}
mseg++;
if (mseg != seg)
*mseg = *seg;
}
#endif
kdebug("Mapped Object [%s]:", what);
kdebug("- elfhdr : %lx", params->elfhdr_addr);
kdebug("- entry : %lx", params->entry_addr);
kdebug("- PHDR[] : %lx", params->ph_addr);
kdebug("- DYNAMIC[]: %lx", params->dynamic_addr);
seg = loadmap->segs;
for (loop = 0; loop < loadmap->nsegs; loop++, seg++)
kdebug("- LOAD[%d] : %08llx-%08llx [va=%llx ms=%llx]",
loop,
(unsigned long long) seg->addr,
(unsigned long long) seg->addr + seg->p_memsz - 1,
(unsigned long long) seg->p_vaddr,
(unsigned long long) seg->p_memsz);
return 0;
dynamic_error:
printk("ELF FDPIC %s with invalid DYNAMIC section (inode=%lu)\n",
what, file_inode(file)->i_ino);
return -ELIBBAD;
}
/*****************************************************************************/
/*
* map a file with constant displacement under uClinux
*/
#ifndef CONFIG_MMU
static int elf_fdpic_map_file_constdisp_on_uclinux(
struct elf_fdpic_params *params,
struct file *file,
struct mm_struct *mm)
{
struct elf_fdpic_loadseg *seg;
struct elf_phdr *phdr;
unsigned long load_addr, base = ULONG_MAX, top = 0, maddr = 0;
int loop, ret;
load_addr = params->load_addr;
seg = params->loadmap->segs;
/* determine the bounds of the contiguous overall allocation we must
* make */
phdr = params->phdrs;
for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
if (params->phdrs[loop].p_type != PT_LOAD)
continue;
if (base > phdr->p_vaddr)
base = phdr->p_vaddr;
if (top < phdr->p_vaddr + phdr->p_memsz)
top = phdr->p_vaddr + phdr->p_memsz;
}
/* allocate one big anon block for everything */
maddr = vm_mmap(NULL, load_addr, top - base,
PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, 0);
if (IS_ERR_VALUE(maddr))
return (int) maddr;
if (load_addr != 0)
load_addr += PAGE_ALIGN(top - base);
/* and then load the file segments into it */
phdr = params->phdrs;
for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
if (params->phdrs[loop].p_type != PT_LOAD)
continue;
seg->addr = maddr + (phdr->p_vaddr - base);
seg->p_vaddr = phdr->p_vaddr;
seg->p_memsz = phdr->p_memsz;
ret = read_code(file, seg->addr, phdr->p_offset,
phdr->p_filesz);
if (ret < 0)
return ret;
/* map the ELF header address if in this segment */
if (phdr->p_offset == 0)
params->elfhdr_addr = seg->addr;
/* clear any space allocated but not loaded */
if (phdr->p_filesz < phdr->p_memsz) {
if (clear_user((void *) (seg->addr + phdr->p_filesz),
phdr->p_memsz - phdr->p_filesz))
return -EFAULT;
}
if (mm) {
if (phdr->p_flags & PF_X) {
if (!mm->start_code) {
mm->start_code = seg->addr;
mm->end_code = seg->addr +
phdr->p_memsz;
}
} else if (!mm->start_data) {
mm->start_data = seg->addr;
mm->end_data = seg->addr + phdr->p_memsz;
}
}
seg++;
}
return 0;
}
#endif
/*****************************************************************************/
/*
* map a binary by direct mmap() of the individual PT_LOAD segments
*/
static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
struct file *file,
struct mm_struct *mm)
{
struct elf_fdpic_loadseg *seg;
struct elf_phdr *phdr;
unsigned long load_addr, delta_vaddr;
int loop, dvset;
load_addr = params->load_addr;
delta_vaddr = 0;
dvset = 0;
seg = params->loadmap->segs;
/* deal with each load segment separately */
phdr = params->phdrs;
for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
unsigned long maddr, disp, excess, excess1;
int prot = 0, flags;
if (phdr->p_type != PT_LOAD)
continue;
kdebug("[LOAD] va=%lx of=%lx fs=%lx ms=%lx",
(unsigned long) phdr->p_vaddr,
(unsigned long) phdr->p_offset,
(unsigned long) phdr->p_filesz,
(unsigned long) phdr->p_memsz);
/* determine the mapping parameters */
if (phdr->p_flags & PF_R) prot |= PROT_READ;
if (phdr->p_flags & PF_W) prot |= PROT_WRITE;
if (phdr->p_flags & PF_X) prot |= PROT_EXEC;
flags = MAP_PRIVATE;
maddr = 0;
switch (params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) {
case ELF_FDPIC_FLAG_INDEPENDENT:
/* PT_LOADs are independently locatable */
break;
case ELF_FDPIC_FLAG_HONOURVADDR:
/* the specified virtual address must be honoured */
maddr = phdr->p_vaddr;
flags |= MAP_FIXED;
break;
case ELF_FDPIC_FLAG_CONSTDISP:
/* constant displacement
* - can be mapped anywhere, but must be mapped as a
* unit
*/
if (!dvset) {
maddr = load_addr;
delta_vaddr = phdr->p_vaddr;
dvset = 1;
} else {
maddr = load_addr + phdr->p_vaddr - delta_vaddr;
flags |= MAP_FIXED;
}
break;
case ELF_FDPIC_FLAG_CONTIGUOUS:
/* contiguity handled later */
break;
default:
BUG();
}
maddr &= PAGE_MASK;
/* create the mapping */
disp = phdr->p_vaddr & ~PAGE_MASK;
maddr = vm_mmap(file, maddr, phdr->p_memsz + disp, prot, flags,
phdr->p_offset - disp);
kdebug("mmap[%d] <file> sz=%llx pr=%x fl=%x of=%llx --> %08lx",
loop, (unsigned long long) phdr->p_memsz + disp,
prot, flags, (unsigned long long) phdr->p_offset - disp,
maddr);
if (IS_ERR_VALUE(maddr))
return (int) maddr;
if ((params->flags & ELF_FDPIC_FLAG_ARRANGEMENT) ==
ELF_FDPIC_FLAG_CONTIGUOUS)
load_addr += PAGE_ALIGN(phdr->p_memsz + disp);
seg->addr = maddr + disp;
seg->p_vaddr = phdr->p_vaddr;
seg->p_memsz = phdr->p_memsz;
/* map the ELF header address if in this segment */
if (phdr->p_offset == 0)
params->elfhdr_addr = seg->addr;
/* clear the bit between beginning of mapping and beginning of
* PT_LOAD */
if (prot & PROT_WRITE && disp > 0) {
kdebug("clear[%d] ad=%lx sz=%lx", loop, maddr, disp);
if (clear_user((void __user *) maddr, disp))
return -EFAULT;
maddr += disp;
}
/* clear any space allocated but not loaded
* - on uClinux we can just clear the lot
* - on MMU linux we'll get a SIGBUS beyond the last page
* extant in the file
*/
excess = phdr->p_memsz - phdr->p_filesz;
excess1 = PAGE_SIZE - ((maddr + phdr->p_filesz) & ~PAGE_MASK);
#ifdef CONFIG_MMU
if (excess > excess1) {
unsigned long xaddr = maddr + phdr->p_filesz + excess1;
unsigned long xmaddr;
flags |= MAP_FIXED | MAP_ANONYMOUS;
xmaddr = vm_mmap(NULL, xaddr, excess - excess1,
prot, flags, 0);
kdebug("mmap[%d] <anon>"
" ad=%lx sz=%lx pr=%x fl=%x of=0 --> %08lx",
loop, xaddr, excess - excess1, prot, flags,
xmaddr);
if (xmaddr != xaddr)
return -ENOMEM;
}
if (prot & PROT_WRITE && excess1 > 0) {
kdebug("clear[%d] ad=%lx sz=%lx",
loop, maddr + phdr->p_filesz, excess1);
if (clear_user((void __user *) maddr + phdr->p_filesz,
excess1))
return -EFAULT;
}
#else
if (excess > 0) {
kdebug("clear[%d] ad=%llx sz=%lx", loop,
(unsigned long long) maddr + phdr->p_filesz,
excess);
if (clear_user((void *) maddr + phdr->p_filesz, excess))
return -EFAULT;
}
#endif
if (mm) {
if (phdr->p_flags & PF_X) {
if (!mm->start_code) {
mm->start_code = maddr;
mm->end_code = maddr + phdr->p_memsz;
}
} else if (!mm->start_data) {
mm->start_data = maddr;
mm->end_data = maddr + phdr->p_memsz;
}
}
seg++;
}
return 0;
}
/*****************************************************************************/
/*
* ELF-FDPIC core dumper
*
* Modelled on fs/exec.c:aout_core_dump()
* Jeremy Fitzhardinge <jeremy@sw.oz.au>
*
* Modelled on fs/binfmt_elf.c core dumper
*/
#ifdef CONFIG_ELF_CORE
struct elf_prstatus_fdpic
{
struct elf_prstatus_common common;
elf_gregset_t pr_reg; /* GP registers */
/* When using FDPIC, the loadmap addresses need to be communicated
* to GDB in order for GDB to do the necessary relocations. The
* fields (below) used to communicate this information are placed
* immediately after ``pr_reg'', so that the loadmap addresses may
* be viewed as part of the register set if so desired.
*/
unsigned long pr_exec_fdpic_loadmap;
unsigned long pr_interp_fdpic_loadmap;
int pr_fpvalid; /* True if math co-processor being used. */
};
/* An ELF note in memory */
struct memelfnote
{
const char *name;
int type;
unsigned int datasz;
void *data;
};
static int notesize(struct memelfnote *en)
{
int sz;
sz = sizeof(struct elf_note);
sz += roundup(strlen(en->name) + 1, 4);
sz += roundup(en->datasz, 4);
return sz;
}
/* #define DEBUG */
static int writenote(struct memelfnote *men, struct coredump_params *cprm)
{
struct elf_note en;
en.n_namesz = strlen(men->name) + 1;
en.n_descsz = men->datasz;
en.n_type = men->type;
return dump_emit(cprm, &en, sizeof(en)) &&
dump_emit(cprm, men->name, en.n_namesz) && dump_align(cprm, 4) &&
dump_emit(cprm, men->data, men->datasz) && dump_align(cprm, 4);
}
static inline void fill_elf_fdpic_header(struct elfhdr *elf, int segs)
{
memcpy(elf->e_ident, ELFMAG, SELFMAG);
elf->e_ident[EI_CLASS] = ELF_CLASS;
elf->e_ident[EI_DATA] = ELF_DATA;
elf->e_ident[EI_VERSION] = EV_CURRENT;
elf->e_ident[EI_OSABI] = ELF_OSABI;
memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
elf->e_type = ET_CORE;
elf->e_machine = ELF_ARCH;
elf->e_version = EV_CURRENT;
elf->e_entry = 0;
elf->e_phoff = sizeof(struct elfhdr);
elf->e_shoff = 0;
elf->e_flags = ELF_FDPIC_CORE_EFLAGS;
elf->e_ehsize = sizeof(struct elfhdr);
elf->e_phentsize = sizeof(struct elf_phdr);
elf->e_phnum = segs;
elf->e_shentsize = 0;
elf->e_shnum = 0;
elf->e_shstrndx = 0;
return;
}
static inline void fill_elf_note_phdr(struct elf_phdr *phdr, int sz, loff_t offset)
{
phdr->p_type = PT_NOTE;
phdr->p_offset = offset;
phdr->p_vaddr = 0;
phdr->p_paddr = 0;
phdr->p_filesz = sz;
phdr->p_memsz = 0;
phdr->p_flags = 0;
phdr->p_align = 4;
return;
}
static inline void fill_note(struct memelfnote *note, const char *name, int type,
unsigned int sz, void *data)
{
note->name = name;
note->type = type;
note->datasz = sz;
note->data = data;
return;
}
/*
* fill up all the fields in prstatus from the given task struct, except
* registers which need to be filled up separately.
*/
static void fill_prstatus(struct elf_prstatus_common *prstatus,
struct task_struct *p, long signr)
{
prstatus->pr_info.si_signo = prstatus->pr_cursig = signr;
prstatus->pr_sigpend = p->pending.signal.sig[0];
prstatus->pr_sighold = p->blocked.sig[0];
rcu_read_lock();
prstatus->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));
rcu_read_unlock();
prstatus->pr_pid = task_pid_vnr(p);
prstatus->pr_pgrp = task_pgrp_vnr(p);
prstatus->pr_sid = task_session_vnr(p);
if (thread_group_leader(p)) {
struct task_cputime cputime;
/*
* This is the record for the group leader. It shows the
* group-wide total, not its individual thread total.
*/
thread_group_cputime(p, &cputime);
prstatus->pr_utime = ns_to_kernel_old_timeval(cputime.utime);
prstatus->pr_stime = ns_to_kernel_old_timeval(cputime.stime);
} else {
u64 utime, stime;
task_cputime(p, &utime, &stime);
prstatus->pr_utime = ns_to_kernel_old_timeval(utime);
prstatus->pr_stime = ns_to_kernel_old_timeval(stime);
}
prstatus->pr_cutime = ns_to_kernel_old_timeval(p->signal->cutime);
prstatus->pr_cstime = ns_to_kernel_old_timeval(p->signal->cstime);
}
static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
struct mm_struct *mm)
{
const struct cred *cred;
unsigned int i, len;
unsigned int state;
/* first copy the parameters from user space */
memset(psinfo, 0, sizeof(struct elf_prpsinfo));
len = mm->arg_end - mm->arg_start;
if (len >= ELF_PRARGSZ)
len = ELF_PRARGSZ - 1;
if (copy_from_user(&psinfo->pr_psargs,
(const char __user *) mm->arg_start, len))
return -EFAULT;
for (i = 0; i < len; i++)
if (psinfo->pr_psargs[i] == 0)
psinfo->pr_psargs[i] = ' ';
psinfo->pr_psargs[len] = 0;
rcu_read_lock();
psinfo->pr_ppid = task_pid_vnr(rcu_dereference(p->real_parent));
rcu_read_unlock();
psinfo->pr_pid = task_pid_vnr(p);
psinfo->pr_pgrp = task_pgrp_vnr(p);
psinfo->pr_sid = task_session_vnr(p);
state = READ_ONCE(p->__state);
i = state ? ffz(~state) + 1 : 0;
psinfo->pr_state = i;
psinfo->pr_sname = (i > 5) ? '.' : "RSDTZW"[i];
psinfo->pr_zomb = psinfo->pr_sname == 'Z';
psinfo->pr_nice = task_nice(p);
psinfo->pr_flag = p->flags;
rcu_read_lock();
cred = __task_cred(p);
SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid));
SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid));
rcu_read_unlock();
get_task_comm(psinfo->pr_fname, p);
return 0;
}
/* Here is the structure in which status of each thread is captured. */
struct elf_thread_status
{
struct elf_thread_status *next;
struct elf_prstatus_fdpic prstatus; /* NT_PRSTATUS */
elf_fpregset_t fpu; /* NT_PRFPREG */
struct memelfnote notes[2];
int num_notes;
};
/*
* In order to add the specific thread information for the elf file format,
* we need to keep a linked list of every thread's pr_status and then create
* a single section for them in the final core file.
*/
static struct elf_thread_status *elf_dump_thread_status(long signr, struct task_struct *p, int *sz)
{
const struct user_regset_view *view = task_user_regset_view(p);
struct elf_thread_status *t;
int i, ret;
t = kzalloc(sizeof(struct elf_thread_status), GFP_KERNEL);
if (!t)
return t;
fill_prstatus(&t->prstatus.common, p, signr);
t->prstatus.pr_exec_fdpic_loadmap = p->mm->context.exec_fdpic_loadmap;
t->prstatus.pr_interp_fdpic_loadmap = p->mm->context.interp_fdpic_loadmap;
regset_get(p, &view->regsets[0],
sizeof(t->prstatus.pr_reg), &t->prstatus.pr_reg);
fill_note(&t->notes[0], "CORE", NT_PRSTATUS, sizeof(t->prstatus),
&t->prstatus);
t->num_notes++;
*sz += notesize(&t->notes[0]);
for (i = 1; i < view->n; ++i) {
const struct user_regset *regset = &view->regsets[i];
if (regset->core_note_type != NT_PRFPREG)
continue;
if (regset->active && regset->active(p, regset) <= 0)
continue;
ret = regset_get(p, regset, sizeof(t->fpu), &t->fpu);
if (ret >= 0)
t->prstatus.pr_fpvalid = 1;
break;
}
if (t->prstatus.pr_fpvalid) {
fill_note(&t->notes[1], "CORE", NT_PRFPREG, sizeof(t->fpu),
&t->fpu);
t->num_notes++;
*sz += notesize(&t->notes[1]);
}
return t;
}
static void fill_extnum_info(struct elfhdr *elf, struct elf_shdr *shdr4extnum,
elf_addr_t e_shoff, int segs)
{
elf->e_shoff = e_shoff;
elf->e_shentsize = sizeof(*shdr4extnum);
elf->e_shnum = 1;
elf->e_shstrndx = SHN_UNDEF;
memset(shdr4extnum, 0, sizeof(*shdr4extnum));
shdr4extnum->sh_type = SHT_NULL;
shdr4extnum->sh_size = elf->e_shnum;
shdr4extnum->sh_link = elf->e_shstrndx;
shdr4extnum->sh_info = segs;
}
/*
* dump the segments for an MMU process
*/
static bool elf_fdpic_dump_segments(struct coredump_params *cprm,
struct core_vma_metadata *vma_meta,
int vma_count)
{
int i;
for (i = 0; i < vma_count; i++) {
struct core_vma_metadata *meta = vma_meta + i;
if (!dump_user_range(cprm, meta->start, meta->dump_size))
return false;
}
return true;
}
/*
* Actual dumper
*
* This is a two-pass process; first we find the offsets of the bits,
* and then they are actually written out. If we run out of core limit
* we just truncate.
*/
static int elf_fdpic_core_dump(struct coredump_params *cprm)
{
int has_dumped = 0;
int segs;
int i;
struct elfhdr *elf = NULL;
loff_t offset = 0, dataoff;
struct memelfnote psinfo_note, auxv_note;
struct elf_prpsinfo *psinfo = NULL; /* NT_PRPSINFO */
struct elf_thread_status *thread_list = NULL;
int thread_status_size = 0;
elf_addr_t *auxv;
struct elf_phdr *phdr4note = NULL;
struct elf_shdr *shdr4extnum = NULL;
Elf_Half e_phnum;
elf_addr_t e_shoff;
struct core_thread *ct;
struct elf_thread_status *tmp;
/* alloc memory for large data structures: too large to be on stack */
elf = kmalloc(sizeof(*elf), GFP_KERNEL);
if (!elf)
goto end_coredump;
psinfo = kmalloc(sizeof(*psinfo), GFP_KERNEL);
if (!psinfo)
goto end_coredump;
for (ct = current->signal->core_state->dumper.next;
ct; ct = ct->next) {
tmp = elf_dump_thread_status(cprm->siginfo->si_signo,
ct->task, &thread_status_size);
if (!tmp)
goto end_coredump;
tmp->next = thread_list;
thread_list = tmp;
}
/* now collect the dump for the current */
tmp = elf_dump_thread_status(cprm->siginfo->si_signo,
current, &thread_status_size);
if (!tmp)
goto end_coredump;
tmp->next = thread_list;
thread_list = tmp;
segs = cprm->vma_count + elf_core_extra_phdrs(cprm);
/* for notes section */
segs++;
/* If segs > PN_XNUM(0xffff), then e_phnum overflows. To avoid
* this, kernel supports extended numbering. Have a look at
* include/linux/elf.h for further information. */
e_phnum = segs > PN_XNUM ? PN_XNUM : segs;
/* Set up header */
fill_elf_fdpic_header(elf, e_phnum);
has_dumped = 1;
/*
* Set up the notes in similar form to SVR4 core dumps made
* with info from their /proc.
*/
fill_psinfo(psinfo, current->group_leader, current->mm);
fill_note(&psinfo_note, "CORE", NT_PRPSINFO, sizeof(*psinfo), psinfo);
thread_status_size += notesize(&psinfo_note);
auxv = (elf_addr_t *) current->mm->saved_auxv;
i = 0;
do
i += 2;
while (auxv[i - 2] != AT_NULL);
fill_note(&auxv_note, "CORE", NT_AUXV, i * sizeof(elf_addr_t), auxv);
thread_status_size += notesize(&auxv_note);
offset = sizeof(*elf); /* ELF header */
offset += segs * sizeof(struct elf_phdr); /* Program headers */
/* Write notes phdr entry */
phdr4note = kmalloc(sizeof(*phdr4note), GFP_KERNEL);
if (!phdr4note)
goto end_coredump;
fill_elf_note_phdr(phdr4note, thread_status_size, offset);
offset += thread_status_size;
/* Page-align dumped data */
dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
offset += cprm->vma_data_size;
offset += elf_core_extra_data_size(cprm);
e_shoff = offset;
if (e_phnum == PN_XNUM) {
shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
if (!shdr4extnum)
goto end_coredump;
fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
}
offset = dataoff;
if (!dump_emit(cprm, elf, sizeof(*elf)))
goto end_coredump;
if (!dump_emit(cprm, phdr4note, sizeof(*phdr4note)))
goto end_coredump;
/* write program headers for segments dump */
for (i = 0; i < cprm->vma_count; i++) {
struct core_vma_metadata *meta = cprm->vma_meta + i;
struct elf_phdr phdr;
size_t sz;
sz = meta->end - meta->start;
phdr.p_type = PT_LOAD;
phdr.p_offset = offset;
phdr.p_vaddr = meta->start;
phdr.p_paddr = 0;
phdr.p_filesz = meta->dump_size;
phdr.p_memsz = sz;
offset += phdr.p_filesz;
phdr.p_flags = 0;
if (meta->flags & VM_READ)
phdr.p_flags |= PF_R;
if (meta->flags & VM_WRITE)
phdr.p_flags |= PF_W;
if (meta->flags & VM_EXEC)
phdr.p_flags |= PF_X;
phdr.p_align = ELF_EXEC_PAGESIZE;
if (!dump_emit(cprm, &phdr, sizeof(phdr)))
goto end_coredump;
}
if (!elf_core_write_extra_phdrs(cprm, offset))
goto end_coredump;
/* write out the notes section */
if (!writenote(thread_list->notes, cprm))
goto end_coredump;
if (!writenote(&psinfo_note, cprm))
goto end_coredump;
if (!writenote(&auxv_note, cprm))
goto end_coredump;
for (i = 1; i < thread_list->num_notes; i++)
if (!writenote(thread_list->notes + i, cprm))
goto end_coredump;
/* write out the thread status notes section */
for (tmp = thread_list->next; tmp; tmp = tmp->next) {
for (i = 0; i < tmp->num_notes; i++)
if (!writenote(&tmp->notes[i], cprm))
goto end_coredump;
}
dump_skip_to(cprm, dataoff);
if (!elf_fdpic_dump_segments(cprm, cprm->vma_meta, cprm->vma_count))
goto end_coredump;
if (!elf_core_write_extra_data(cprm))
goto end_coredump;
if (e_phnum == PN_XNUM) {
if (!dump_emit(cprm, shdr4extnum, sizeof(*shdr4extnum)))
goto end_coredump;
}
if (cprm->file->f_pos != offset) {
/* Sanity check */
printk(KERN_WARNING
"elf_core_dump: file->f_pos (%lld) != offset (%lld)\n",
cprm->file->f_pos, offset);
}
end_coredump:
while (thread_list) {
tmp = thread_list;
thread_list = thread_list->next;
kfree(tmp);
}
kfree(phdr4note);
kfree(elf);
kfree(psinfo);
kfree(shdr4extnum);
return has_dumped;
}
#endif /* CONFIG_ELF_CORE */
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