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Allow PT_INTERP and PT_NOTES segments to be located anywhere in the

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executable image.  Keep one page (arbitrary) limit on the max allowed
size of the PT_NOTES.

The ELF image activators still require that program headers of the
executable are fully contained in the first page of the image file.

Reviewed by:	emaste, jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D3871
This commit is contained in:
Konstantin Belousov 2015-10-14 18:27:35 +00:00
parent 8fd566ab3e
commit 6c775eb64e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=289322
1 changed files with 100 additions and 40 deletions
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140
sys/kern/imgact_elf.c
View File

@ -721,21 +721,22 @@ __elfN(load_file)(struct proc *p, const char *file, u_long *addr,
static int
__CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
{
const Elf_Ehdr *hdr = (const Elf_Ehdr *)imgp->image_header;
struct thread *td;
const Elf_Ehdr *hdr;
const Elf_Phdr *phdr;
Elf_Auxargs *elf_auxargs;
struct vmspace *vmspace;
vm_prot_t prot;
u_long text_size = 0, data_size = 0, total_size = 0;
u_long text_addr = 0, data_addr = 0;
u_long seg_size, seg_addr;
u_long addr, baddr, et_dyn_addr, entry = 0, proghdr = 0;
int32_t osrel = 0;
int error = 0, i, n, interp_name_len = 0;
const char *err_str = NULL, *interp = NULL, *newinterp = NULL;
const char *err_str, *newinterp;
char *interp, *interp_buf, *path;
Elf_Brandinfo *brand_info;
char *path;
struct sysentvec *sv;
vm_prot_t prot;
u_long text_size, data_size, total_size, text_addr, data_addr;
u_long seg_size, seg_addr, addr, baddr, et_dyn_addr, entry, proghdr;
int32_t osrel;
int error, i, n, interp_name_len, have_interp;
hdr = (const Elf_Ehdr *)imgp->image_header;
/*
* Do we have a valid ELF header ?
@ -763,8 +764,17 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
uprintf("Unaligned program headers\n");
return (ENOEXEC);
}
n = 0;
n = error = 0;
baddr = 0;
osrel = 0;
text_size = data_size = total_size = text_addr = data_addr = 0;
entry = proghdr = 0;
interp_name_len = 0;
err_str = newinterp = NULL;
interp = interp_buf = NULL;
td = curthread;
for (i = 0; i < hdr->e_phnum; i++) {
switch (phdr[i].p_type) {
case PT_LOAD:
@ -774,14 +784,32 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
break;
case PT_INTERP:
/* Path to interpreter */
if (phdr[i].p_filesz > MAXPATHLEN ||
phdr[i].p_offset > PAGE_SIZE ||
phdr[i].p_filesz > PAGE_SIZE - phdr[i].p_offset) {
if (phdr[i].p_filesz > MAXPATHLEN) {
uprintf("Invalid PT_INTERP\n");
return (ENOEXEC);
error = ENOEXEC;
goto ret;
}
interp = imgp->image_header + phdr[i].p_offset;
interp_name_len = phdr[i].p_filesz;
if (phdr[i].p_offset > PAGE_SIZE ||
interp_name_len > PAGE_SIZE - phdr[i].p_offset) {
VOP_UNLOCK(imgp->vp, 0);
interp_buf = malloc(interp_name_len + 1, M_TEMP,
M_WAITOK);
vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
error = vn_rdwr(UIO_READ, imgp->vp, interp_buf,
interp_name_len, phdr[i].p_offset,
UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
NOCRED, NULL, td);
if (error != 0) {
uprintf("i/o error PT_INTERP\n");
goto ret;
}
interp_buf[interp_name_len] = '\0';
interp = interp_buf;
} else {
interp = __DECONST(char *, imgp->image_header) +
phdr[i].p_offset;
}
break;
case PT_GNU_STACK:
if (__elfN(nxstack))
@ -797,12 +825,14 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
if (brand_info == NULL) {
uprintf("ELF binary type \"%u\" not known.\n",
hdr->e_ident[EI_OSABI]);
return (ENOEXEC);
error = ENOEXEC;
goto ret;
}
if (hdr->e_type == ET_DYN) {
if ((brand_info->flags & BI_CAN_EXEC_DYN) == 0) {
uprintf("Cannot execute shared object\n");
return (ENOEXEC);
error = ENOEXEC;
goto ret;
}
/*
* Honour the base load address from the dso if it is
@ -835,8 +865,8 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
imgp->proc->p_sysent = sv;
vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
if (error)
return (error);
if (error != 0)
goto ret;
for (i = 0; i < hdr->e_phnum; i++) {
switch (phdr[i].p_type) {
@ -849,7 +879,7 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
phdr[i].p_memsz, phdr[i].p_filesz, prot,
sv->sv_pagesize);
if (error != 0)
return (error);
goto ret;
/*
* If this segment contains the program headers,
@ -921,7 +951,8 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
if (err_str != NULL) {
PROC_UNLOCK(imgp->proc);
uprintf("%s\n", err_str);
return (ENOMEM);
error = ENOMEM;
goto ret;
}
vmspace = imgp->proc->p_vmspace;
@ -936,14 +967,14 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
* calculation is that it leaves room for the heap to grow to
* its maximum allowed size.
*/
addr = round_page((vm_offset_t)vmspace->vm_daddr + lim_max(curthread,
addr = round_page((vm_offset_t)vmspace->vm_daddr + lim_max(td,
RLIMIT_DATA));
PROC_UNLOCK(imgp->proc);
imgp->entry_addr = entry;
if (interp != NULL) {
int have_interp = FALSE;
have_interp = FALSE;
VOP_UNLOCK(imgp->vp, 0);
if (brand_info->emul_path != NULL &&
brand_info->emul_path[0] != '\0') {
@ -969,7 +1000,7 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
if (error != 0) {
uprintf("ELF interpreter %s not found\n", interp);
return (error);
goto ret;
}
} else
addr = et_dyn_addr;
@ -993,6 +1024,8 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
imgp->reloc_base = addr;
imgp->proc->p_osrel = osrel;
ret:
free(interp_buf, M_TEMP);
return (error);
}
@ -2122,19 +2155,42 @@ __elfN(parse_notes)(struct image_params *imgp, Elf_Brandnote *checknote,
{
const Elf_Note *note, *note0, *note_end;
const char *note_name;
int i;
char *buf;
int i, error;
boolean_t res;
if (pnote == NULL || pnote->p_offset > PAGE_SIZE ||
pnote->p_filesz > PAGE_SIZE - pnote->p_offset)
/* We need some limit, might as well use PAGE_SIZE. */
if (pnote == NULL || pnote->p_filesz > PAGE_SIZE)
return (FALSE);
note = note0 = (const Elf_Note *)(imgp->image_header + pnote->p_offset);
note_end = (const Elf_Note *)(imgp->image_header +
pnote->p_offset + pnote->p_filesz);
ASSERT_VOP_LOCKED(imgp->vp, "parse_notes");
if (pnote->p_offset > PAGE_SIZE ||
pnote->p_filesz > PAGE_SIZE - pnote->p_offset) {
VOP_UNLOCK(imgp->vp, 0);
buf = malloc(pnote->p_filesz, M_TEMP, M_WAITOK);
vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY);
error = vn_rdwr(UIO_READ, imgp->vp, buf, pnote->p_filesz,
pnote->p_offset, UIO_SYSSPACE, IO_NODELOCKED,
curthread->td_ucred, NOCRED, NULL, curthread);
if (error != 0) {
uprintf("i/o error PT_NOTE\n");
res = FALSE;
goto ret;
}
note = note0 = (const Elf_Note *)buf;
note_end = (const Elf_Note *)(buf + pnote->p_filesz);
} else {
note = note0 = (const Elf_Note *)(imgp->image_header +
pnote->p_offset);
note_end = (const Elf_Note *)(imgp->image_header +
pnote->p_offset + pnote->p_filesz);
buf = NULL;
}
for (i = 0; i < 100 && note >= note0 && note < note_end; i++) {
if (!aligned(note, Elf32_Addr) || (const char *)note_end -
(const char *)note < sizeof(Elf_Note))
return (FALSE);
(const char *)note < sizeof(Elf_Note)) {
res = FALSE;
goto ret;
}
if (note->n_namesz != checknote->hdr.n_namesz ||
note->n_descsz != checknote->hdr.n_descsz ||
note->n_type != checknote->hdr.n_type)
@ -2150,17 +2206,21 @@ __elfN(parse_notes)(struct image_params *imgp, Elf_Brandnote *checknote,
* from the ELF OSABI-note if necessary.
*/
if ((checknote->flags & BN_TRANSLATE_OSREL) != 0 &&
checknote->trans_osrel != NULL)
return (checknote->trans_osrel(note, osrel));
return (TRUE);
checknote->trans_osrel != NULL) {
res = checknote->trans_osrel(note, osrel);
goto ret;
}
res = TRUE;
goto ret;
nextnote:
note = (const Elf_Note *)((const char *)(note + 1) +
roundup2(note->n_namesz, ELF_NOTE_ROUNDSIZE) +
roundup2(note->n_descsz, ELF_NOTE_ROUNDSIZE));
}
return (FALSE);
res = FALSE;
ret:
free(buf, M_TEMP);
return (res);
}
/*