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Merge branch 'exec_rm_compat' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc

Browse Source 
* 'exec_rm_compat' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc:
  exec: document acct_arg_size()
  exec: unify do_execve/compat_do_execve code
  exec: introduce struct user_arg_ptr
  exec: introduce get_user_arg_ptr() helper
This commit is contained in:
Linus Torvalds
2011-05-23 08:28:34 -07:00
parent 34b064569e ae6b585eeb
commit 4d9dec4db2
3 changed files with 100 additions and 264 deletions
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235
fs/compat.c
View File

@@ -1306,241 +1306,6 @@ compat_sys_openat(unsigned int dfd, const char __user *filename, int flags, int
return do_sys_open(dfd, filename, flags, mode); return do_sys_open(dfd, filename, flags, mode);
} }
/*
* compat_count() counts the number of arguments/envelopes. It is basically
* a copy of count() from fs/exec.c, except that it works with 32 bit argv
* and envp pointers.
*/
static int compat_count(compat_uptr_t __user *argv, int max)
{
int i = 0;
if (argv != NULL) {
for (;;) {
compat_uptr_t p;
if (get_user(p, argv))
return -EFAULT;
if (!p)
break;
argv++;
if (i++ >= max)
return -E2BIG;
if (fatal_signal_pending(current))
return -ERESTARTNOHAND;
cond_resched();
}
}
return i;
}
/*
* compat_copy_strings() is basically a copy of copy_strings() from fs/exec.c
* except that it works with 32 bit argv and envp pointers.
*/
static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
struct linux_binprm *bprm)
{
struct page *kmapped_page = NULL;
char *kaddr = NULL;
unsigned long kpos = 0;
int ret;
while (argc-- > 0) {
compat_uptr_t str;
int len;
unsigned long pos;
if (get_user(str, argv+argc) ||
!(len = strnlen_user(compat_ptr(str), MAX_ARG_STRLEN))) {
ret = -EFAULT;
goto out;
}
if (len > MAX_ARG_STRLEN) {
ret = -E2BIG;
goto out;
}
/* We're going to work our way backwords. */
pos = bprm->p;
str += len;
bprm->p -= len;
while (len > 0) {
int offset, bytes_to_copy;
if (fatal_signal_pending(current)) {
ret = -ERESTARTNOHAND;
goto out;
}
cond_resched();
offset = pos % PAGE_SIZE;
if (offset == 0)
offset = PAGE_SIZE;
bytes_to_copy = offset;
if (bytes_to_copy > len)
bytes_to_copy = len;
offset -= bytes_to_copy;
pos -= bytes_to_copy;
str -= bytes_to_copy;
len -= bytes_to_copy;
if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
struct page *page;
page = get_arg_page(bprm, pos, 1);
if (!page) {
ret = -E2BIG;
goto out;
}
if (kmapped_page) {
flush_kernel_dcache_page(kmapped_page);
kunmap(kmapped_page);
put_page(kmapped_page);
}
kmapped_page = page;
kaddr = kmap(kmapped_page);
kpos = pos & PAGE_MASK;
flush_cache_page(bprm->vma, kpos,
page_to_pfn(kmapped_page));
}
if (copy_from_user(kaddr+offset, compat_ptr(str),
bytes_to_copy)) {
ret = -EFAULT;
goto out;
}
}
}
ret = 0;
out:
if (kmapped_page) {
flush_kernel_dcache_page(kmapped_page);
kunmap(kmapped_page);
put_page(kmapped_page);
}
return ret;
}
/*
* compat_do_execve() is mostly a copy of do_execve(), with the exception
* that it processes 32 bit argv and envp pointers.
*/
int compat_do_execve(char * filename,
compat_uptr_t __user *argv,
compat_uptr_t __user *envp,
struct pt_regs * regs)
{
struct linux_binprm *bprm;
struct file *file;
struct files_struct *displaced;
bool clear_in_exec;
int retval;
retval = unshare_files(&displaced);
if (retval)
goto out_ret;
retval = -ENOMEM;
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
if (!bprm)
goto out_files;
retval = prepare_bprm_creds(bprm);
if (retval)
goto out_free;
retval = check_unsafe_exec(bprm);
if (retval < 0)
goto out_free;
clear_in_exec = retval;
current->in_execve = 1;
file = open_exec(filename);
retval = PTR_ERR(file);
if (IS_ERR(file))
goto out_unmark;
sched_exec();
bprm->file = file;
bprm->filename = filename;
bprm->interp = filename;
retval = bprm_mm_init(bprm);
if (retval)
goto out_file;
bprm->argc = compat_count(argv, MAX_ARG_STRINGS);
if ((retval = bprm->argc) < 0)
goto out;
bprm->envc = compat_count(envp, MAX_ARG_STRINGS);
if ((retval = bprm->envc) < 0)
goto out;
retval = prepare_binprm(bprm);
if (retval < 0)
goto out;
retval = copy_strings_kernel(1, &bprm->filename, bprm);
if (retval < 0)
goto out;
bprm->exec = bprm->p;
retval = compat_copy_strings(bprm->envc, envp, bprm);
if (retval < 0)
goto out;
retval = compat_copy_strings(bprm->argc, argv, bprm);
if (retval < 0)
goto out;
retval = search_binary_handler(bprm, regs);
if (retval < 0)
goto out;
/* execve succeeded */
current->fs->in_exec = 0;
current->in_execve = 0;
acct_update_integrals(current);
free_bprm(bprm);
if (displaced)
put_files_struct(displaced);
return retval;
out:
if (bprm->mm) {
acct_arg_size(bprm, 0);
mmput(bprm->mm);
}
out_file:
if (bprm->file) {
allow_write_access(bprm->file);
fput(bprm->file);
}
out_unmark:
if (clear_in_exec)
current->fs->in_exec = 0;
current->in_execve = 0;
out_free:
free_bprm(bprm);
out_files:
if (displaced)
reset_files_struct(displaced);
out_ret:
return retval;
}
#define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t)) #define __COMPAT_NFDBITS (8 * sizeof(compat_ulong_t))
static int poll_select_copy_remaining(struct timespec *end_time, void __user *p, static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,

125
fs/exec.c
View File

@@ -55,6 +55,7 @@
#include <linux/fs_struct.h> #include <linux/fs_struct.h>
#include <linux/pipe_fs_i.h> #include <linux/pipe_fs_i.h>
#include <linux/oom.h> #include <linux/oom.h>
#include <linux/compat.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <asm/mmu_context.h> #include <asm/mmu_context.h>
@@ -166,8 +167,13 @@ out:
} }
#ifdef CONFIG_MMU #ifdef CONFIG_MMU
/*
void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) * The nascent bprm->mm is not visible until exec_mmap() but it can
* use a lot of memory, account these pages in current->mm temporary
* for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
* change the counter back via acct_arg_size(0).
*/
static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{ {
struct mm_struct *mm = current->mm; struct mm_struct *mm = current->mm;
long diff = (long)(pages - bprm->vma_pages); long diff = (long)(pages - bprm->vma_pages);
@@ -186,7 +192,7 @@ void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
#endif #endif
} }
struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write) int write)
{ {
struct page *page; struct page *page;
@@ -305,11 +311,11 @@ static bool valid_arg_len(struct linux_binprm *bprm, long len)
#else #else
void acct_arg_size(struct linux_binprm *bprm, unsigned long pages) static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
{ {
} }
struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos, static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write) int write)
{ {
struct page *page; struct page *page;
@@ -398,22 +404,56 @@ err:
return err; return err;
} }
struct user_arg_ptr {
#ifdef CONFIG_COMPAT
bool is_compat;
#endif
union {
const char __user *const __user *native;
#ifdef CONFIG_COMPAT
compat_uptr_t __user *compat;
#endif
} ptr;
};
static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
{
const char __user *native;
#ifdef CONFIG_COMPAT
if (unlikely(argv.is_compat)) {
compat_uptr_t compat;
if (get_user(compat, argv.ptr.compat + nr))
return ERR_PTR(-EFAULT);
return compat_ptr(compat);
}
#endif
if (get_user(native, argv.ptr.native + nr))
return ERR_PTR(-EFAULT);
return native;
}
/* /*
* count() counts the number of strings in array ARGV. * count() counts the number of strings in array ARGV.
*/ */
static int count(const char __user * const __user * argv, int max) static int count(struct user_arg_ptr argv, int max)
{ {
int i = 0; int i = 0;
if (argv != NULL) { if (argv.ptr.native != NULL) {
for (;;) { for (;;) {
const char __user * p; const char __user *p = get_user_arg_ptr(argv, i);
if (get_user(p, argv))
return -EFAULT;
if (!p) if (!p)
break; break;
argv++;
if (IS_ERR(p))
return -EFAULT;
if (i++ >= max) if (i++ >= max)
return -E2BIG; return -E2BIG;
@@ -430,7 +470,7 @@ static int count(const char __user * const __user * argv, int max)
* processes's memory to the new process's stack. The call to get_user_pages() * processes's memory to the new process's stack. The call to get_user_pages()
* ensures the destination page is created and not swapped out. * ensures the destination page is created and not swapped out.
*/ */
static int copy_strings(int argc, const char __user *const __user *argv, static int copy_strings(int argc, struct user_arg_ptr argv,
struct linux_binprm *bprm) struct linux_binprm *bprm)
{ {
struct page *kmapped_page = NULL; struct page *kmapped_page = NULL;
@@ -443,16 +483,18 @@ static int copy_strings(int argc, const char __user *const __user *argv,
int len; int len;
unsigned long pos; unsigned long pos;
if (get_user(str, argv+argc) || ret = -EFAULT;
!(len = strnlen_user(str, MAX_ARG_STRLEN))) { str = get_user_arg_ptr(argv, argc);
ret = -EFAULT; if (IS_ERR(str))
goto out; goto out;
}
if (!valid_arg_len(bprm, len)) { len = strnlen_user(str, MAX_ARG_STRLEN);
ret = -E2BIG; if (!len)
goto out;
ret = -E2BIG;
if (!valid_arg_len(bprm, len))
goto out; goto out;
}
/* We're going to work our way backwords. */ /* We're going to work our way backwords. */
pos = bprm->p; pos = bprm->p;
@@ -519,14 +561,19 @@ out:
/* /*
* Like copy_strings, but get argv and its values from kernel memory. * Like copy_strings, but get argv and its values from kernel memory.
*/ */
int copy_strings_kernel(int argc, const char *const *argv, int copy_strings_kernel(int argc, const char *const *__argv,
struct linux_binprm *bprm) struct linux_binprm *bprm)
{ {
int r; int r;
mm_segment_t oldfs = get_fs(); mm_segment_t oldfs = get_fs();
struct user_arg_ptr argv = {
.ptr.native = (const char __user *const __user *)__argv,
};
set_fs(KERNEL_DS); set_fs(KERNEL_DS);
r = copy_strings(argc, (const char __user *const __user *)argv, bprm); r = copy_strings(argc, argv, bprm);
set_fs(oldfs); set_fs(oldfs);
return r; return r;
} }
EXPORT_SYMBOL(copy_strings_kernel); EXPORT_SYMBOL(copy_strings_kernel);
@@ -1379,10 +1426,10 @@ EXPORT_SYMBOL(search_binary_handler);
/* /*
* sys_execve() executes a new program. * sys_execve() executes a new program.
*/ */
int do_execve(const char * filename, static int do_execve_common(const char *filename,
const char __user *const __user *argv, struct user_arg_ptr argv,
const char __user *const __user *envp, struct user_arg_ptr envp,
struct pt_regs * regs) struct pt_regs *regs)
{ {
struct linux_binprm *bprm; struct linux_binprm *bprm;
struct file *file; struct file *file;
@@ -1489,6 +1536,34 @@ out_ret:
return retval; return retval;
} }
int do_execve(const char *filename,
const char __user *const __user *__argv,
const char __user *const __user *__envp,
struct pt_regs *regs)
{
struct user_arg_ptr argv = { .ptr.native = __argv };
struct user_arg_ptr envp = { .ptr.native = __envp };
return do_execve_common(filename, argv, envp, regs);
}
#ifdef CONFIG_COMPAT
int compat_do_execve(char *filename,
compat_uptr_t __user *__argv,
compat_uptr_t __user *__envp,
struct pt_regs *regs)
{
struct user_arg_ptr argv = {
.is_compat = true,
.ptr.compat = __argv,
};
struct user_arg_ptr envp = {
.is_compat = true,
.ptr.compat = __envp,
};
return do_execve_common(filename, argv, envp, regs);
}
#endif
void set_binfmt(struct linux_binfmt *new) void set_binfmt(struct linux_binfmt *new)
{ {
struct mm_struct *mm = current->mm; struct mm_struct *mm = current->mm;

4
include/linux/binfmts.h
View File

@@ -60,10 +60,6 @@ struct linux_binprm {
unsigned long loader, exec; unsigned long loader, exec;
}; };
extern void acct_arg_size(struct linux_binprm *bprm, unsigned long pages);
extern struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
int write);
#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0 #define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0
#define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT) #define BINPRM_FLAGS_ENFORCE_NONDUMP (1 << BINPRM_FLAGS_ENFORCE_NONDUMP_BIT)