original development tree for Linux kernel GTP module; now long in mainline.
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/*
* linux/fs/binfmt_som.c
*
* These are the functions used to load SOM format executables as used
* by HP-UX.
*
* Copyright 1999 Matthew Wilcox <willy@bofh.ai>
* based on binfmt_elf which is
* Copyright 1993, 1994: Eric Youngdale (ericy@cais.com).
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/binfmts.h>
#include <linux/som.h>
#include <linux/string.h>
#include <linux/file.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/shm.h>
#include <linux/personality.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <linux/elf.h>
static int load_som_binary(struct linux_binprm * bprm, struct pt_regs * regs);
static int load_som_library(struct file *);
/*
* If we don't support core dumping, then supply a NULL so we
* don't even try.
*/
#if 0
static int som_core_dump(struct coredump_params *cprm);
#else
#define som_core_dump NULL
#endif
#define SOM_PAGESTART(_v) ((_v) & ~(unsigned long)(SOM_PAGESIZE-1))
#define SOM_PAGEOFFSET(_v) ((_v) & (SOM_PAGESIZE-1))
#define SOM_PAGEALIGN(_v) (((_v) + SOM_PAGESIZE - 1) & ~(SOM_PAGESIZE - 1))
static struct linux_binfmt som_format = {
.module = THIS_MODULE,
.load_binary = load_som_binary,
.load_shlib = load_som_library,
.core_dump = som_core_dump,
.min_coredump = SOM_PAGESIZE
};
/*
* create_som_tables() parses the env- and arg-strings in new user
* memory and creates the pointer tables from them, and puts their
* addresses on the "stack", returning the new stack pointer value.
*/
static void create_som_tables(struct linux_binprm *bprm)
{
char **argv, **envp;
int argc = bprm->argc;
int envc = bprm->envc;
unsigned long p;
unsigned long *sp;
/* Word-align the stack pointer */
sp = (unsigned long *)((bprm->p + 3) & ~3);
envp = (char **) sp;
sp += envc + 1;
argv = (char **) sp;
sp += argc + 1;
__put_user((unsigned long) envp,++sp);
__put_user((unsigned long) argv,++sp);
__put_user(argc, ++sp);
bprm->p = (unsigned long) sp;
p = current->mm->arg_start;
while (argc-- > 0) {
__put_user((char *)p,argv++);
p += strlen_user((char *)p);
}
__put_user(NULL, argv);
current->mm->arg_end = current->mm->env_start = p;
while (envc-- > 0) {
__put_user((char *)p,envp++);
p += strlen_user((char *)p);
}
__put_user(NULL, envp);
current->mm->env_end = p;
}
static int check_som_header(struct som_hdr *som_ex)
{
int *buf = (int *)som_ex;
int i, ck;
if (som_ex->system_id != SOM_SID_PARISC_1_0 &&
som_ex->system_id != SOM_SID_PARISC_1_1 &&
som_ex->system_id != SOM_SID_PARISC_2_0)
return -ENOEXEC;
if (som_ex->a_magic != SOM_EXEC_NONSHARE &&
som_ex->a_magic != SOM_EXEC_SHARE &&
som_ex->a_magic != SOM_EXEC_DEMAND)
return -ENOEXEC;
if (som_ex->version_id != SOM_ID_OLD &&
som_ex->version_id != SOM_ID_NEW)
return -ENOEXEC;
ck = 0;
for (i=0; i<32; i++)
ck ^= buf[i];
if (ck != 0)
return -ENOEXEC;
return 0;
}
static int map_som_binary(struct file *file,
const struct som_exec_auxhdr *hpuxhdr)
{
unsigned long code_start, code_size, data_start, data_size;
unsigned long bss_start, som_brk;
int retval;
int prot = PROT_READ | PROT_EXEC;
int flags = MAP_FIXED|MAP_PRIVATE|MAP_DENYWRITE|MAP_EXECUTABLE;
mm_segment_t old_fs = get_fs();
set_fs(get_ds());
code_start = SOM_PAGESTART(hpuxhdr->exec_tmem);
code_size = SOM_PAGEALIGN(hpuxhdr->exec_tsize);
current->mm->start_code = code_start;
current->mm->end_code = code_start + code_size;
down_write(&current->mm->mmap_sem);
retval = do_mmap(file, code_start, code_size, prot,
flags, SOM_PAGESTART(hpuxhdr->exec_tfile));
up_write(&current->mm->mmap_sem);
if (retval < 0 && retval > -1024)
goto out;
data_start = SOM_PAGESTART(hpuxhdr->exec_dmem);
data_size = SOM_PAGEALIGN(hpuxhdr->exec_dsize);
current->mm->start_data = data_start;
current->mm->end_data = bss_start = data_start + data_size;
down_write(&current->mm->mmap_sem);
retval = do_mmap(file, data_start, data_size,
prot | PROT_WRITE, flags,
SOM_PAGESTART(hpuxhdr->exec_dfile));
up_write(&current->mm->mmap_sem);
if (retval < 0 && retval > -1024)
goto out;
som_brk = bss_start + SOM_PAGEALIGN(hpuxhdr->exec_bsize);
current->mm->start_brk = current->mm->brk = som_brk;
down_write(&current->mm->mmap_sem);
retval = do_mmap(NULL, bss_start, som_brk - bss_start,
prot | PROT_WRITE, MAP_FIXED | MAP_PRIVATE, 0);
up_write(&current->mm->mmap_sem);
if (retval > 0 || retval < -1024)
retval = 0;
out:
set_fs(old_fs);
return retval;
}
/*
* These are the functions used to load SOM executables and shared
* libraries. There is no binary dependent code anywhere else.
*/
static int
load_som_binary(struct linux_binprm * bprm, struct pt_regs * regs)
{
int retval;
unsigned int size;
unsigned long som_entry;
struct som_hdr *som_ex;
struct som_exec_auxhdr *hpuxhdr;
/* Get the exec-header */
som_ex = (struct som_hdr *) bprm->buf;
retval = check_som_header(som_ex);
if (retval != 0)
goto out;
/* Now read in the auxiliary header information */
retval = -ENOMEM;
size = som_ex->aux_header_size;
if (size > SOM_PAGESIZE)
goto out;
hpuxhdr = kmalloc(size, GFP_KERNEL);
if (!hpuxhdr)
goto out;
retval = kernel_read(bprm->file, som_ex->aux_header_location,
(char *) hpuxhdr, size);
if (retval != size) {
if (retval >= 0)
retval = -EIO;
goto out_free;
}
/* Flush all traces of the currently running executable */
retval = flush_old_exec(bprm);
if (retval)
goto out_free;
/* OK, This is the point of no return */
current->flags &= ~PF_FORKNOEXEC;
current->personality = PER_HPUX;
setup_new_exec(bprm);
/* Set the task size for HP-UX processes such that
* the gateway page is outside the address space.
* This can be fixed later, but for now, this is much
* easier.
*/
current->thread.task_size = 0xc0000000;
/* Set map base to allow enough room for hp-ux heap growth */
current->thread.map_base = 0x80000000;
retval = map_som_binary(bprm->file, hpuxhdr);
if (retval < 0)
goto out_free;
som_entry = hpuxhdr->exec_entry;
kfree(hpuxhdr);
set_binfmt(&som_format);
CRED: Make execve() take advantage of copy-on-write credentials Make execve() take advantage of copy-on-write credentials, allowing it to set up the credentials in advance, and then commit the whole lot after the point of no return. This patch and the preceding patches have been tested with the LTP SELinux testsuite. This patch makes several logical sets of alteration: (1) execve(). The credential bits from struct linux_binprm are, for the most part, replaced with a single credentials pointer (bprm->cred). This means that all the creds can be calculated in advance and then applied at the point of no return with no possibility of failure. I would like to replace bprm->cap_effective with: cap_isclear(bprm->cap_effective) but this seems impossible due to special behaviour for processes of pid 1 (they always retain their parent's capability masks where normally they'd be changed - see cap_bprm_set_creds()). The following sequence of events now happens: (a) At the start of do_execve, the current task's cred_exec_mutex is locked to prevent PTRACE_ATTACH from obsoleting the calculation of creds that we make. (a) prepare_exec_creds() is then called to make a copy of the current task's credentials and prepare it. This copy is then assigned to bprm->cred. This renders security_bprm_alloc() and security_bprm_free() unnecessary, and so they've been removed. (b) The determination of unsafe execution is now performed immediately after (a) rather than later on in the code. The result is stored in bprm->unsafe for future reference. (c) prepare_binprm() is called, possibly multiple times. (i) This applies the result of set[ug]id binaries to the new creds attached to bprm->cred. Personality bit clearance is recorded, but now deferred on the basis that the exec procedure may yet fail. (ii) This then calls the new security_bprm_set_creds(). This should calculate the new LSM and capability credentials into *bprm->cred. This folds together security_bprm_set() and parts of security_bprm_apply_creds() (these two have been removed). Anything that might fail must be done at this point. (iii) bprm->cred_prepared is set to 1. bprm->cred_prepared is 0 on the first pass of the security calculations, and 1 on all subsequent passes. This allows SELinux in (ii) to base its calculations only on the initial script and not on the interpreter. (d) flush_old_exec() is called to commit the task to execution. This performs the following steps with regard to credentials: (i) Clear pdeath_signal and set dumpable on certain circumstances that may not be covered by commit_creds(). (ii) Clear any bits in current->personality that were deferred from (c.i). (e) install_exec_creds() [compute_creds() as was] is called to install the new credentials. This performs the following steps with regard to credentials: (i) Calls security_bprm_committing_creds() to apply any security requirements, such as flushing unauthorised files in SELinux, that must be done before the credentials are changed. This is made up of bits of security_bprm_apply_creds() and security_bprm_post_apply_creds(), both of which have been removed. This function is not allowed to fail; anything that might fail must have been done in (c.ii). (ii) Calls commit_creds() to apply the new credentials in a single assignment (more or less). Possibly pdeath_signal and dumpable should be part of struct creds. (iii) Unlocks the task's cred_replace_mutex, thus allowing PTRACE_ATTACH to take place. (iv) Clears The bprm->cred pointer as the credentials it was holding are now immutable. (v) Calls security_bprm_committed_creds() to apply any security alterations that must be done after the creds have been changed. SELinux uses this to flush signals and signal handlers. (f) If an error occurs before (d.i), bprm_free() will call abort_creds() to destroy the proposed new credentials and will then unlock cred_replace_mutex. No changes to the credentials will have been made. (2) LSM interface. A number of functions have been changed, added or removed: (*) security_bprm_alloc(), ->bprm_alloc_security() (*) security_bprm_free(), ->bprm_free_security() Removed in favour of preparing new credentials and modifying those. (*) security_bprm_apply_creds(), ->bprm_apply_creds() (*) security_bprm_post_apply_creds(), ->bprm_post_apply_creds() Removed; split between security_bprm_set_creds(), security_bprm_committing_creds() and security_bprm_committed_creds(). (*) security_bprm_set(), ->bprm_set_security() Removed; folded into security_bprm_set_creds(). (*) security_bprm_set_creds(), ->bprm_set_creds() New. The new credentials in bprm->creds should be checked and set up as appropriate. bprm->cred_prepared is 0 on the first call, 1 on the second and subsequent calls. (*) security_bprm_committing_creds(), ->bprm_committing_creds() (*) security_bprm_committed_creds(), ->bprm_committed_creds() New. Apply the security effects of the new credentials. This includes closing unauthorised files in SELinux. This function may not fail. When the former is called, the creds haven't yet been applied to the process; when the latter is called, they have. The former may access bprm->cred, the latter may not. (3) SELinux. SELinux has a number of changes, in addition to those to support the LSM interface changes mentioned above: (a) The bprm_security_struct struct has been removed in favour of using the credentials-under-construction approach. (c) flush_unauthorized_files() now takes a cred pointer and passes it on to inode_has_perm(), file_has_perm() and dentry_open(). Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
13 years ago
install_exec_creds(bprm);
setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
create_som_tables(bprm);
current->mm->start_stack = bprm->p;
#if 0
printk("(start_brk) %08lx\n" , (unsigned long) current->mm->start_brk);
printk("(end_code) %08lx\n" , (unsigned long) current->mm->end_code);
printk("(start_code) %08lx\n" , (unsigned long) current->mm->start_code);
printk("(end_data) %08lx\n" , (unsigned long) current->mm->end_data);
printk("(start_stack) %08lx\n" , (unsigned long) current->mm->start_stack);
printk("(brk) %08lx\n" , (unsigned long) current->mm->brk);
#endif
map_hpux_gateway_page(current,current->mm);
start_thread_som(regs, som_entry, bprm->p);
return 0;
/* error cleanup */
out_free:
kfree(hpuxhdr);
out:
return retval;
}
static int load_som_library(struct file *f)
{
/* No lib support in SOM yet. gizza chance.. */
return -ENOEXEC;
}
/* Install the SOM loader.
* N.B. We *rely* on the table being the right size with the
* right number of free slots...
*/
static int __init init_som_binfmt(void)
{
register_binfmt(&som_format);
return 0;
}
static void __exit exit_som_binfmt(void)
{
/* Remove the SOM loader. */
unregister_binfmt(&som_format);
}
core_initcall(init_som_binfmt);
module_exit(exit_som_binfmt);
MODULE_LICENSE("GPL");