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Fix do_xmap() to work under SElinux. Also trim unneeded code.

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committer: jreiser <jreiser> 1141413353 +0000
This commit is contained in:
John Reiser 2006-03-03 19:15:53 +00:00
parent e87f5521c1
commit a791e96e00
1 changed files with 19 additions and 32 deletions
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51
src/stub/m_lx_elfppc32.c
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@ -47,6 +47,8 @@
// "file" util
**************************************************************************/
extern void exit (int __status) __attribute__ ((__nothrow__)) __attribute__ ((__noreturn__));
typedef struct {
size_t size; // must be first to match size[0] uncompressed size
char *buf;
@ -155,14 +157,6 @@ ERR_LAB
}
}
// Create (or find) an escape hatch to use when munmapping ourselves the stub.
// Called by do_xmap to create it, and by assembler code to find it.
static void *
make_hatch(Elf32_Phdr const *const phdr)
{
return 0;
}
static void
upx_bzero(char *p, size_t len)
{
@ -176,7 +170,7 @@ upx_bzero(char *p, size_t len)
static void
auxv_up(Elf32_auxv_t *av, int const type, unsigned const value)
{
if (av && 0==(1&(int)av)) /* PT_INTERP usually inhibits, except for hatch */
if (av)
for (;; ++av) {
if (av->a_type==type || (av->a_type==AT_IGNORE && type!=AT_NULL)) {
av->a_type = type;
@ -203,13 +197,13 @@ auxv_up(Elf32_auxv_t *av, int const type, unsigned const value)
// and mmap that much, to be sure that a kernel using exec-shield-randomize
// won't place the first piece in a way that leaves no room for the rest.
static unsigned long // returns relocation constant
xfind_pages(unsigned mflags, Elf32_Phdr const *phdr, int phnum,
xfind_pages(unsigned mflags, Elf32_Phdr const *phdr, int phnum, int fdi,
char **const p_brk
)
{
size_t lo= ~0, hi= 0, szlo= 0;
char *addr;
mflags += MAP_PRIVATE | MAP_ANONYMOUS; // '+' can optimize better than '|'
mflags += MAP_PRIVATE | MAP_ANONYMOUS | MAP_DENYWRITE; // '+' can optimize better than '|'
for (; --phnum>=0; ++phdr) if (PT_LOAD==phdr->p_type) {
if (phdr->p_vaddr < lo) {
lo = phdr->p_vaddr;
@ -223,9 +217,9 @@ xfind_pages(unsigned mflags, Elf32_Phdr const *phdr, int phnum,
lo -= ~PAGE_MASK & lo; // round down to page boundary
hi = PAGE_MASK & (hi - lo - PAGE_MASK -1); // page length
szlo = PAGE_MASK & (szlo - PAGE_MASK -1); // page length
addr = mmap((void *)lo, hi, PROT_READ|PROT_WRITE|PROT_EXEC, mflags, 0, 0);
addr = mmap((void *)lo, hi, PROT_READ|PROT_WRITE|PROT_EXEC, mflags, fdi, 0);
*p_brk = hi + addr; // the logical value of brk(0)
munmap(szlo + addr, hi - szlo); // desirable if PT_LOAD non-contiguous
mprotect(szlo + addr, hi - szlo, PROT_NONE); // but keep the frames!
return (unsigned long)addr - lo;
}
@ -243,7 +237,7 @@ do_xmap(
(char const *)ehdr);
char *v_brk;
unsigned long const reloc = xfind_pages(
((ET_DYN!=ehdr->e_type) ? MAP_FIXED : 0), phdr, ehdr->e_phnum, &v_brk);
((ET_DYN!=ehdr->e_type) ? MAP_FIXED : 0), phdr, ehdr->e_phnum, fdi, &v_brk);
int j;
for (j=0; j < ehdr->e_phnum; ++phdr, ++j)
if (xi && PT_PHDR==phdr->p_type) {
@ -261,7 +255,7 @@ do_xmap(
addr += reloc;
haddr += reloc;
if (addr != mmap(addr, mlen, PROT_READ | PROT_WRITE,
if (addr != mmap(addr, mlen, prot | (xi ? PROT_WRITE : 0),
MAP_FIXED | MAP_PRIVATE | (xi ? MAP_ANONYMOUS : 0),
fdi, phdr->p_offset - frag) ) {
err_exit(8);
@ -269,19 +263,18 @@ do_xmap(
if (xi) {
unpackExtent(xi, &xo, f_decompress, f_unf);
}
bzero(addr, frag); // fragment at lo end
frag = (-mlen) &~ PAGE_MASK; // distance to next page boundary
bzero(mlen+addr, frag); // fragment at hi end
if (xi) {
void *const hatch = make_hatch(phdr);
if (0!=hatch) {
/* always update AT_NULL, especially for compressed PT_INTERP */
auxv_up((Elf32_auxv_t *)(~1 & (int)av), AT_NULL, (unsigned)hatch);
}
if (xi || (PROT_WRITE & prot)) {
bzero(addr, frag); // fragment at lo end
}
if (0!=mprotect(addr, mlen, prot)) {
err_exit(10);
frag = (-mlen) &~ PAGE_MASK; // distance to next page boundary
if (xi || (PROT_WRITE & prot)) {
bzero(mlen+addr, frag); // fragment at hi end
}
if (xi) {
if (0!=mprotect(addr, mlen, prot)) {
err_exit(10);
ERR_LAB
}
}
addr += mlen + frag; /* page boundary on hi end */
if (addr < haddr) { // need pages for .bss
@ -291,12 +284,6 @@ ERR_LAB
}
}
}
if (xi) { // 1st call (main); also have (0!=av) here
if (ET_DYN!=ehdr->e_type) {
// Needed only if compressed shell script invokes compressed shell.
brk(v_brk);
}
}
return ehdr->e_entry + reloc;
}