projects/linux·commit b6a2fea3

mm: variable length argument support

b6a2fea3 · Ollie Wild <[email protected]> · 2007-07-19 01:48:16 -07:00

Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly from
the old mm into the new mm.

We create the new mm before the binfmt code runs, and place the new stack at
the very top of the address space.  Once the binfmt code runs and figures out
where the stack should be, we move it downwards.

It is a bit peculiar in that we have one task with two mm's, one of which is
inactive.

[[email protected]: limit stack size]
Signed-off-by: Ollie Wild <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: <[email protected]>
Cc: Hugh Dickins <[email protected]>
[[email protected]: unexport bprm_mm_init]
Signed-off-by: Adrian Bunk <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
b6a2fea39318e43fee84fa7b0b90d68bed92d2ba
Parents
bdf4c48a

Changes

15 files changed · +554 −453

Only the first 600 diff lines are shown. Download the complete patch.

arch/ia64/ia32/binfmt_elf32.c

View file
diff --git a/arch/ia64/ia32/binfmt_elf32.c b/arch/ia64/ia32/binfmt_elf32.c
index 6f4d3d0..e1189ba 100644
--- a/arch/ia64/ia32/binfmt_elf32.c
+++ b/arch/ia64/ia32/binfmt_elf32.c
@@ -195,62 +195,27 @@ ia64_elf32_init (struct pt_regs *regs)
ia32_load_state(current);
}
+/*
+ * Undo the override of setup_arg_pages() without this ia32_setup_arg_pages()
+ * will suffer infinite self recursion.
+ */
+#undef setup_arg_pages
+
int
ia32_setup_arg_pages (struct linux_binprm *bprm, int executable_stack)
{
- unsigned long stack_base;
- struct vm_area_struct *mpnt;
- struct mm_struct *mm = current->mm;
- int i, ret;
-
- stack_base = IA32_STACK_TOP - MAX_ARG_PAGES*PAGE_SIZE;
- mm->arg_start = bprm->p + stack_base;
-
- bprm->p += stack_base;
- if (bprm->loader)
- bprm->loader += stack_base;
- bprm->exec += stack_base;
-
- mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
- if (!mpnt)
- return -ENOMEM;
-
- down_write(&current->mm->mmap_sem);
- {
- mpnt->vm_mm = current->mm;
- mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;
- mpnt->vm_end = IA32_STACK_TOP;
- if (executable_stack == EXSTACK_ENABLE_X)
- mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC;
- else if (executable_stack == EXSTACK_DISABLE_X)
- mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
- else
- mpnt->vm_flags = VM_STACK_FLAGS;
- mpnt->vm_page_prot = (mpnt->vm_flags & VM_EXEC)?
- PAGE_COPY_EXEC: PAGE_COPY;
- if ((ret = insert_vm_struct(current->mm, mpnt))) {
- up_write(&current->mm->mmap_sem);
- kmem_cache_free(vm_area_cachep, mpnt);
- return ret;
- }
- current->mm->stack_vm = current->mm->total_vm = vma_pages(mpnt);
+ int ret;
+
+ ret = setup_arg_pages(bprm, IA32_STACK_TOP, executable_stack);
+ if (!ret) {
+ /*
+ * Can't do it in ia64_elf32_init(). Needs to be done before
+ * calls to elf32_map()
+ */
+ current->thread.ppl = ia32_init_pp_list();
}
- for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
- struct page *page = bprm->page[i];
- if (page) {
- bprm->page[i] = NULL;
- install_arg_page(mpnt, page, stack_base);
- }
- stack_base += PAGE_SIZE;
- }
- up_write(&current->mm->mmap_sem);
-
- /* Can't do it in ia64_elf32_init(). Needs to be done before calls to
- elf32_map() */
- current->thread.ppl = ia32_init_pp_list();
-
- return 0;
+ return ret;
}
static void

arch/x86_64/ia32/ia32_aout.c

View file
diff --git a/arch/x86_64/ia32/ia32_aout.c b/arch/x86_64/ia32/ia32_aout.c
index fe83edb..0878137 100644
--- a/arch/x86_64/ia32/ia32_aout.c
+++ b/arch/x86_64/ia32/ia32_aout.c
@@ -404,7 +404,7 @@ beyond_if:
set_brk(current->mm->start_brk, current->mm->brk);
- retval = ia32_setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
+ retval = setup_arg_pages(bprm, IA32_STACK_TOP, EXSTACK_DEFAULT);
if (retval < 0) {
/* Someone check-me: is this error path enough? */
send_sig(SIGKILL, current, 0);

arch/x86_64/ia32/ia32_binfmt.c

View file
diff --git a/arch/x86_64/ia32/ia32_binfmt.c b/arch/x86_64/ia32/ia32_binfmt.c
index 185399b..ed56a88 100644
--- a/arch/x86_64/ia32/ia32_binfmt.c
+++ b/arch/x86_64/ia32/ia32_binfmt.c
@@ -232,9 +232,6 @@ do { \
#define load_elf_binary load_elf32_binary
#define ELF_PLAT_INIT(r, load_addr) elf32_init(r)
-#define setup_arg_pages(bprm, stack_top, exec_stack) \
- ia32_setup_arg_pages(bprm, stack_top, exec_stack)
-int ia32_setup_arg_pages(struct linux_binprm *bprm, unsigned long stack_top, int executable_stack);
#undef start_thread
#define start_thread(regs,new_rip,new_rsp) do { \
@@ -286,61 +283,6 @@ static void elf32_init(struct pt_regs *regs)
me->thread.es = __USER_DS;
}
-int ia32_setup_arg_pages(struct linux_binprm *bprm, unsigned long stack_top,
- int executable_stack)
-{
- unsigned long stack_base;
- struct vm_area_struct *mpnt;
- struct mm_struct *mm = current->mm;
- int i, ret;
-
- stack_base = stack_top - MAX_ARG_PAGES * PAGE_SIZE;
- mm->arg_start = bprm->p + stack_base;
-
- bprm->p += stack_base;
- if (bprm->loader)
- bprm->loader += stack_base;
- bprm->exec += stack_base;
-
- mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
- if (!mpnt)
- return -ENOMEM;
-
- down_write(&mm->mmap_sem);
- {
- mpnt->vm_mm = mm;
- mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;
- mpnt->vm_end = stack_top;
- if (executable_stack == EXSTACK_ENABLE_X)
- mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC;
- else if (executable_stack == EXSTACK_DISABLE_X)
- mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
- else
- mpnt->vm_flags = VM_STACK_FLAGS;
- mpnt->vm_page_prot = (mpnt->vm_flags & VM_EXEC) ?
- PAGE_COPY_EXEC : PAGE_COPY;
- if ((ret = insert_vm_struct(mm, mpnt))) {
- up_write(&mm->mmap_sem);
- kmem_cache_free(vm_area_cachep, mpnt);
- return ret;
- }
- mm->stack_vm = mm->total_vm = vma_pages(mpnt);
- }
-
- for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
- struct page *page = bprm->page[i];
- if (page) {
- bprm->page[i] = NULL;
- install_arg_page(mpnt, page, stack_base);
- }
- stack_base += PAGE_SIZE;
- }
- up_write(&mm->mmap_sem);
-
- return 0;
-}
-EXPORT_SYMBOL(ia32_setup_arg_pages);
-
#ifdef CONFIG_SYSCTL
/* Register vsyscall32 into the ABI table */
#include <linux/sysctl.h>

fs/binfmt_elf.c

View file
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a27e42b..295cbaa 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -148,6 +148,7 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
elf_addr_t *elf_info;
int ei_index = 0;
struct task_struct *tsk = current;
+ struct vm_area_struct *vma;
/*
* If this architecture has a platform capability string, copy it
@@ -234,6 +235,15 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
sp = (elf_addr_t __user *)bprm->p;
#endif
+
+ /*
+ * Grow the stack manually; some architectures have a limit on how
+ * far ahead a user-space access may be in order to grow the stack.
+ */
+ vma = find_extend_vma(current->mm, bprm->p);
+ if (!vma)
+ return -EFAULT;
+
/* Now, let's put argc (and argv, envp if appropriate) on the stack */
if (__put_user(argc, sp++))
return -EFAULT;
@@ -254,8 +264,8 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
size_t len;
if (__put_user((elf_addr_t)p, argv++))
return -EFAULT;
- len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);
- if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)
+ len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
+ if (!len || len > MAX_ARG_STRLEN)
return 0;
p += len;
}
@@ -266,8 +276,8 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
size_t len;
if (__put_user((elf_addr_t)p, envp++))
return -EFAULT;
- len = strnlen_user((void __user *)p, PAGE_SIZE*MAX_ARG_PAGES);
- if (!len || len > PAGE_SIZE*MAX_ARG_PAGES)
+ len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
+ if (!len || len > MAX_ARG_STRLEN)
return 0;
p += len;
}
@@ -826,10 +836,6 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
}
/* OK, This is the point of no return */
- current->mm->start_data = 0;
- current->mm->end_data = 0;
- current->mm->end_code = 0;
- current->mm->mmap = NULL;
current->flags &= ~PF_FORKNOEXEC;
current->mm->def_flags = def_flags;
@@ -1051,9 +1057,13 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs)
compute_creds(bprm);
current->flags &= ~PF_FORKNOEXEC;
- create_elf_tables(bprm, &loc->elf_ex,
+ retval = create_elf_tables(bprm, &loc->elf_ex,
(interpreter_type == INTERPRETER_AOUT),
load_addr, interp_load_addr);
+ if (retval < 0) {
+ send_sig(SIGKILL, current, 0);
+ goto out;
+ }
/* N.B. passed_fileno might not be initialized? */
if (interpreter_type == INTERPRETER_AOUT)
current->mm->arg_start += strlen(passed_fileno) + 1;

fs/binfmt_elf_fdpic.c

View file
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 9d62fba..4739506 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -621,8 +621,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
p = (char __user *) current->mm->arg_start;
for (loop = bprm->argc; loop > 0; loop--) {
__put_user((elf_caddr_t) p, argv++);
- len = strnlen_user(p, PAGE_SIZE * MAX_ARG_PAGES);
- if (!len || len > PAGE_SIZE * MAX_ARG_PAGES)
+ len = strnlen_user(p, MAX_ARG_STRLEN);
+ if (!len || len > MAX_ARG_STRLEN)
return -EINVAL;
p += len;
}
@@ -633,8 +633,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
current->mm->env_start = (unsigned long) p;
for (loop = bprm->envc; loop > 0; loop--) {
__put_user((elf_caddr_t)(unsigned long) p, envp++);
- len = strnlen_user(p, PAGE_SIZE * MAX_ARG_PAGES);
- if (!len || len > PAGE_SIZE * MAX_ARG_PAGES)
+ len = strnlen_user(p, MAX_ARG_STRLEN);
+ if (!len || len > MAX_ARG_STRLEN)
return -EINVAL;
p += len;
}

fs/binfmt_misc.c

View file
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 330fd3f..42e94b3 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -126,7 +126,9 @@ static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)
goto _ret;
if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
- remove_arg_zero(bprm);
+ retval = remove_arg_zero(bprm);
+ if (retval)
+ goto _ret;
}
if (fmt->flags & MISC_FMT_OPEN_BINARY) {

fs/binfmt_script.c

View file
diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c
index 304c885..4d0e0f6 100644
--- a/fs/binfmt_script.c
+++ b/fs/binfmt_script.c
@@ -67,7 +67,9 @@ static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
* This is done in reverse order, because of how the
* user environment and arguments are stored.
*/
- remove_arg_zero(bprm);
+ retval = remove_arg_zero(bprm);
+ if (retval)
+ return retval;
retval = copy_strings_kernel(1, &bprm->interp, bprm);
if (retval < 0) return retval;
bprm->argc++;

fs/compat.c

View file
diff --git a/fs/compat.c b/fs/compat.c
index 4db6216..15078ce 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1257,6 +1257,7 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
{
struct page *kmapped_page = NULL;
char *kaddr = NULL;
+ unsigned long kpos = 0;
int ret;
while (argc-- > 0) {
@@ -1265,92 +1266,84 @@ static int compat_copy_strings(int argc, compat_uptr_t __user *argv,
unsigned long pos;
if (get_user(str, argv+argc) ||
- !(len = strnlen_user(compat_ptr(str), bprm->p))) {
+ !(len = strnlen_user(compat_ptr(str), MAX_ARG_STRLEN))) {
ret = -EFAULT;
goto out;
}
- if (bprm->p < len) {
+ if (len > MAX_ARG_STRLEN) {
ret = -E2BIG;
goto out;
}
- bprm->p -= len;
- /* XXX: add architecture specific overflow check here. */
+ /* We're going to work our way backwords. */
pos = bprm->p;
+ str += len;
+ bprm->p -= len;
while (len > 0) {
- int i, new, err;
int offset, bytes_to_copy;
- struct page *page;
offset = pos % PAGE_SIZE;
- i = pos/PAGE_SIZE;
- page = bprm->page[i];
- new = 0;
- if (!page) {
- page = alloc_page(GFP_HIGHUSER);
- bprm->page[i] = page;
- if (!page) {
- ret = -ENOMEM;
+ 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;
+
+#ifdef CONFIG_STACK_GROWSUP
+ ret = expand_stack_downwards(bprm->vma, pos);
+ if (ret < 0) {
+ /* We've exceed the stack rlimit. */
+ ret = -E2BIG;
+ goto out;
+ }
+#endif
+ ret = get_user_pages(current, bprm->mm, pos,
+ 1, 1, 1, &page, NULL);
+ if (ret <= 0) {
+ /* We've exceed the stack rlimit. */
+ ret = -E2BIG;
goto out;
}
- new = 1;
- }
- if (page != kmapped_page) {
- if (kmapped_page)
+ 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 (new && offset)
- memset(kaddr, 0, offset);
- bytes_to_copy = PAGE_SIZE - offset;
- if (bytes_to_copy > len) {
- bytes_to_copy = len;
- if (new)
- memset(kaddr+offset+len, 0,
- PAGE_SIZE-offset-len);
- }
- err = copy_from_user(kaddr+offset, compat_ptr(str),
- bytes_to_copy);
- if (err) {
+ if (copy_from_user(kaddr+offset, compat_ptr(str),
+ bytes_to_copy)) {
ret = -EFAULT;
goto out;
}
-
- pos += bytes_to_copy;
- str += bytes_to_copy;
- len -= bytes_to_copy;
}
}
ret = 0;
out:
- if (kmapped_page)
+ if (kmapped_page) {
+ flush_kernel_dcache_page(kmapped_page);
kunmap(kmapped_page);
- return ret;
-}
-
-#ifdef CONFIG_MMU
-
-#define free_arg_pages(bprm) do { } while (0)
-
-#else
-
-static inline void free_arg_pages(struct linux_binprm *bprm)
-{
- int i;
-
- for (i = 0; i < MAX_ARG_PAGES; i++) {
- if (bprm->page[i])
- __free_page(bprm->page[i]);
- bprm->page[i] = NULL;
+ put_page(kmapped_page);
}
+ return ret;
}
-#endif /* CONFIG_MMU */
-
/*
* compat_do_execve() is mostly a copy of do_execve(), with the exception
* that it processes 32 bit argv and envp pointers.
@@ -1363,7 +1356,6 @@ int compat_do_execve(char * filename,
struct linux_binprm *bprm;
struct file *file;
int retval;
- int i;
retval = -ENOMEM;
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
@@ -1377,24 +1369,19 @@ int compat_do_execve(char * filename,
sched_exec();
- bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
bprm->file = file;
bprm->filename = filename;
bprm->interp = filename;
- bprm->mm = mm_alloc();
- retval = -ENOMEM;
- if (!bprm->mm)
- goto out_file;
- retval = init_new_context(current, bprm->mm);
- if (retval < 0)
- goto out_mm;
+ retval = bprm_mm_init(bprm);
+ if (retval)
+ goto out_file;
- bprm->argc = compat_count(argv, bprm->p / sizeof(compat_uptr_t));
+ bprm->argc = compat_count(argv, MAX_ARG_STRINGS);
if ((retval = bprm->argc) < 0)
goto out_mm;
- bprm->envc = compat_count(envp, bprm->p / sizeof(compat_uptr_t));
+ bprm->envc = compat_count(envp, MAX_ARG_STRINGS);
if ((retval = bprm->envc) < 0)
goto out_mm;
@@ -1421,8 +1408,6 @@ int compat_do_execve(char * filename,
retval = search_binary_handler(bprm, regs);
if (retval >= 0) {
- free_arg_pages(bprm);
-
/* execve success */
security_bprm_free(bprm);
acct_update_integrals(current);
@@ -1431,19 +1416,12 @@ int compat_do_execve(char * filename,
}
out:
- /* Something went wrong, return the inode and free the argument pages*/
- for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
- struct page * page = bprm->page[i];
- if (page)
- __free_page(page);
- }
-
if (bprm->security)
security_bprm_free(bprm);
out_mm:
if (bprm->mm)
- mmdrop(bprm->mm);
+ mmput(bprm->mm);
out_file:
if (bprm->file) {

fs/exec.c

View file
diff --git a/fs/exec.c b/fs/exec.c
index 2e3f795..498f2b3 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -54,6 +54,7 @@
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
+#include <asm/tlb.h>
#ifdef CONFIG_KMOD
#include <linux/kmod.h>
@@ -178,6 +179,207 @@ exit:
goto out;
}
+#ifdef CONFIG_MMU
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ int write)
+{
+ struct page *page;
+ int ret;
+
+#ifdef CONFIG_STACK_GROWSUP
+ if (write) {
+ ret = expand_stack_downwards(bprm->vma, pos);
+ if (ret < 0)
+ return NULL;
+ }
+#endif
+ ret = get_user_pages(current, bprm->mm, pos,
+ 1, write, 1, &page, NULL);
+ if (ret <= 0)
+ return NULL;
+
+ if (write) {
+ struct rlimit *rlim = current->signal->rlim;
+ unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
+
+ /*
+ * Limit to 1/4-th the stack size for the argv+env strings.
+ * This ensures that:
+ * - the remaining binfmt code will not run out of stack space,
+ * - the program will have a reasonable amount of stack left
+ * to work from.
+ */
+ if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
+ put_page(page);
+ return NULL;
+ }
+ }
+
+ return page;
+}
+
+static void put_arg_page(struct page *page)
+{
+ put_page(page);
+}
+
+static void free_arg_page(struct linux_binprm *bprm, int i)
+{
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ struct page *page)
+{
+ flush_cache_page(bprm->vma, pos, page_to_pfn(page));
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{

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include/linux/binfmts.h

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include/linux/mm.h

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kernel/auditsc.c

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mm/mmap.c

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mm/mprotect.c

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mm/mremap.c

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