minix/kernel/system/do_safecopy.c
2010-04-15 18:49:36 +00:00

413 lines
12 KiB
C

/* The kernel call implemented in this file:
* m_type: SYS_SAFECOPYFROM or SYS_SAFECOPYTO or SYS_VSAFECOPY
*
* The parameters for this kernel call are:
* SCP_FROM_TO other endpoint
* SCP_SEG segment in own address space
* SCP_GID grant id
* SCP_OFFSET offset within granted space
* SCP_ADDRESS address in own address space
* SCP_BYTES bytes to be copied
*
* For the vectored variant (do_vsafecopy):
* VSCP_VEC_ADDR address of vector
* VSCP_VEC_SIZE number of significant elements in vector
*/
#include <minix/type.h>
#include <minix/safecopies.h>
#include "kernel/system.h"
#define MAX_INDIRECT_DEPTH 5 /* up to how many indirect grants to follow? */
#define MEM_TOP 0xFFFFFFFFUL
#define USE_COW_SAFECOPY 0
FORWARD _PROTOTYPE(int safecopy, (struct proc *, endpoint_t, endpoint_t,
cp_grant_id_t, int, int, size_t, vir_bytes, vir_bytes, int));
#define HASGRANTTABLE(gr) \
(!RTS_ISSET(gr, RTS_NO_PRIV) && priv(gr) && priv(gr)->s_grant_table > 0)
/*===========================================================================*
* verify_grant *
*===========================================================================*/
PUBLIC int verify_grant(granter, grantee, grant, bytes, access,
offset_in, offset_result, e_granter)
endpoint_t granter, grantee; /* copyee, copyer */
cp_grant_id_t grant; /* grant id */
vir_bytes bytes; /* copy size */
int access; /* direction (read/write) */
vir_bytes offset_in; /* copy offset within grant */
vir_bytes *offset_result; /* copy offset within virtual address space */
endpoint_t *e_granter; /* new granter (magic grants) */
{
static cp_grant_t g;
static int proc_nr;
static const struct proc *granter_proc;
int depth = 0;
do {
/* Get granter process slot (if valid), and check range of
* grant id.
*/
if(!isokendpt(granter, &proc_nr) ) {
printf(
"grant verify failed: invalid granter %d\n", (int) granter);
return(EINVAL);
}
if(!GRANT_VALID(grant)) {
printf(
"grant verify failed: invalid grant %d\n", (int) grant);
return(EINVAL);
}
granter_proc = proc_addr(proc_nr);
/* If there is no priv. structure, or no grant table in the
* priv. structure, or the grant table in the priv. structure
* is too small for the grant, return EPERM.
*/
if(!HASGRANTTABLE(granter_proc)) return EPERM;
if(priv(granter_proc)->s_grant_entries <= grant) {
printf(
"verify_grant: grant verify failed in ep %d "
"proc %d: grant %d out of range "
"for table size %d\n",
granter, proc_nr, grant,
priv(granter_proc)->s_grant_entries);
return(EPERM);
}
/* Copy the grant entry corresponding to this id to see what it
* looks like. If it fails, hide the fact that granter has
* (presumably) set an invalid grant table entry by returning
* EPERM, just like with an invalid grant id.
*/
if(data_copy(granter,
priv(granter_proc)->s_grant_table + sizeof(g)*grant,
KERNEL, (vir_bytes) &g, sizeof(g)) != OK) {
printf(
"verify_grant: grant verify: data_copy failed\n");
return EPERM;
}
/* Check validity. */
if((g.cp_flags & (CPF_USED | CPF_VALID)) !=
(CPF_USED | CPF_VALID)) {
printf(
"verify_grant: grant failed: invalid (%d flags 0x%lx)\n",
grant, g.cp_flags);
return EPERM;
}
/* The given grant may be an indirect grant, that is, a grant
* that provides permission to use a grant given to the
* granter (i.e., for which it is the grantee). This can lead
* to a chain of indirect grants which must be followed back.
*/
if((g.cp_flags & CPF_INDIRECT)) {
/* Stop after a few iterations. There may be a loop. */
if (depth == MAX_INDIRECT_DEPTH) {
printf(
"verify grant: indirect grant verify "
"failed: exceeded maximum depth\n");
return ELOOP;
}
depth++;
/* Verify actual grantee. */
if(g.cp_u.cp_indirect.cp_who_to != grantee &&
grantee != ANY &&
g.cp_u.cp_indirect.cp_who_to != ANY) {
printf(
"verify_grant: indirect grant verify "
"failed: bad grantee\n");
return EPERM;
}
/* Start over with new granter, grant, and grantee. */
grantee = granter;
granter = g.cp_u.cp_indirect.cp_who_from;
grant = g.cp_u.cp_indirect.cp_grant;
}
} while(g.cp_flags & CPF_INDIRECT);
/* Check access of grant. */
if(((g.cp_flags & access) != access)) {
printf(
"verify_grant: grant verify failed: access invalid; want 0x%x, have 0x%x\n",
access, g.cp_flags);
return EPERM;
}
if((g.cp_flags & CPF_DIRECT)) {
/* Don't fiddle around with grants that wrap, arithmetic
* below may be confused.
*/
if(MEM_TOP - g.cp_u.cp_direct.cp_len <
g.cp_u.cp_direct.cp_start - 1) {
printf(
"verify_grant: direct grant verify failed: len too long\n");
return EPERM;
}
/* Verify actual grantee. */
if(g.cp_u.cp_direct.cp_who_to != grantee && grantee != ANY
&& g.cp_u.cp_direct.cp_who_to != ANY) {
printf(
"verify_grant: direct grant verify failed: bad grantee\n");
return EPERM;
}
/* Verify actual copy range. */
if((offset_in+bytes < offset_in) ||
offset_in+bytes > g.cp_u.cp_direct.cp_len) {
printf(
"verify_grant: direct grant verify failed: bad size or range. "
"granted %d bytes @ 0x%lx; wanted %d bytes @ 0x%lx\n",
g.cp_u.cp_direct.cp_len,
g.cp_u.cp_direct.cp_start,
bytes, offset_in);
return EPERM;
}
/* Verify successful - tell caller what address it is. */
*offset_result = g.cp_u.cp_direct.cp_start + offset_in;
*e_granter = granter;
} else if(g.cp_flags & CPF_MAGIC) {
/* Currently, it is hardcoded that only FS may do
* magic grants.
*/
if(granter != FS_PROC_NR) {
printf(
"verify_grant: magic grant verify failed: granter (%d) "
"is not FS (%d)\n", granter, FS_PROC_NR);
return EPERM;
}
/* Verify actual grantee. */
if(g.cp_u.cp_magic.cp_who_to != grantee && grantee != ANY
&& g.cp_u.cp_direct.cp_who_to != ANY) {
printf(
"verify_grant: magic grant verify failed: bad grantee\n");
return EPERM;
}
/* Verify actual copy range. */
if((offset_in+bytes < offset_in) ||
offset_in+bytes > g.cp_u.cp_magic.cp_len) {
printf(
"verify_grant: magic grant verify failed: bad size or range. "
"granted %d bytes @ 0x%lx; wanted %d bytes @ 0x%lx\n",
g.cp_u.cp_magic.cp_len,
g.cp_u.cp_magic.cp_start,
bytes, offset_in);
return EPERM;
}
/* Verify successful - tell caller what address it is. */
*offset_result = g.cp_u.cp_magic.cp_start + offset_in;
*e_granter = g.cp_u.cp_magic.cp_who_from;
} else {
printf(
"verify_grant: grant verify failed: unknown grant type\n");
return EPERM;
}
return OK;
}
/*===========================================================================*
* safecopy *
*===========================================================================*/
PRIVATE int safecopy(caller, granter, grantee, grantid, src_seg, dst_seg, bytes,
g_offset, addr, access)
struct proc * caller;
endpoint_t granter, grantee;
cp_grant_id_t grantid;
int src_seg, dst_seg;
size_t bytes;
vir_bytes g_offset, addr;
int access; /* CPF_READ for a copy from granter to grantee, CPF_WRITE
* for a copy from grantee to granter.
*/
{
static struct vir_addr v_src, v_dst;
static vir_bytes v_offset;
endpoint_t new_granter, *src, *dst;
struct proc *granter_p;
int r;
#if USE_COW_SAFECOPY
vir_bytes size;
#endif
/* See if there is a reasonable grant table. */
if(!(granter_p = endpoint_lookup(granter))) return EINVAL;
if(!HASGRANTTABLE(granter_p)) return EPERM;
/* Decide who is src and who is dst. */
if(access & CPF_READ) {
src = &granter;
dst = &grantee;
} else {
src = &grantee;
dst = &granter;
}
/* Verify permission exists. */
if((r=verify_grant(granter, grantee, grantid, bytes, access,
g_offset, &v_offset, &new_granter)) != OK) {
printf(
"grant %d verify to copy %d->%d by %d failed: err %d\n",
grantid, *src, *dst, grantee, r);
return r;
}
/* verify_grant() can redirect the grantee to someone else,
* meaning the source or destination changes.
*/
granter = new_granter;
/* Now it's a regular copy. */
v_src.segment = src_seg;
v_dst.segment = dst_seg;
v_src.proc_nr_e = *src;
v_dst.proc_nr_e = *dst;
/* Now the offset in virtual addressing is known in 'offset'.
* Depending on the access, this is the source or destination
* address.
*/
if(access & CPF_READ) {
v_src.offset = v_offset;
v_dst.offset = (vir_bytes) addr;
} else {
v_src.offset = (vir_bytes) addr;
v_dst.offset = v_offset;
}
/* Do the regular copy. */
#if USE_COW_SAFECOPY
if(v_offset % CLICK_SIZE != addr % CLICK_SIZE || bytes < CLICK_SIZE) {
/* Give up on COW immediately when offsets are not aligned
* or we are copying less than a page.
*/
return virtual_copy_vmcheck(caller, &v_src, &v_dst, bytes);
}
if((size = v_offset % CLICK_SIZE) != 0) {
/* Normal copy for everything before the first page boundary. */
size = CLICK_SIZE - size;
r = virtual_copy_vmcheck(caller, &v_src, &v_dst, size);
if(r != OK)
return r;
v_src.offset += size;
v_dst.offset += size;
bytes -= size;
}
if((size = bytes / CLICK_SIZE) != 0) {
/* Use COW optimization when copying entire pages. */
size *= CLICK_SIZE;
r = map_invoke_vm(VMPTYPE_COWMAP,
v_dst.proc_nr_e, v_dst.segment, v_dst.offset,
v_src.proc_nr_e, v_src.segment, v_src.offset,
size, 0);
if(r != OK)
return r;
v_src.offset += size;
v_dst.offset += size;
bytes -= size;
}
if(bytes != 0) {
/* Normal copy for everything after the last page boundary. */
r = virtual_copy_vmcheck(caller, &v_src, &v_dst, bytes);
if(r != OK)
return r;
}
return OK;
#else
return virtual_copy_vmcheck(caller, &v_src, &v_dst, bytes);
#endif
}
/*===========================================================================*
* do_safecopy *
*===========================================================================*/
PUBLIC int do_safecopy(struct proc * caller, message * m_ptr)
{
static int access, src_seg, dst_seg;
/* Set src and dst parameters. */
if(m_ptr->m_type == SYS_SAFECOPYFROM) {
src_seg = D;
dst_seg = m_ptr->SCP_SEG;
access = CPF_READ;
} else if(m_ptr->m_type == SYS_SAFECOPYTO) {
src_seg = m_ptr->SCP_SEG;
dst_seg = D;
access = CPF_WRITE;
} else panic("Impossible system call nr.: %d", m_ptr->m_type);
return safecopy(caller, m_ptr->SCP_FROM_TO, caller->p_endpoint,
(cp_grant_id_t) m_ptr->SCP_GID, src_seg, dst_seg,
m_ptr->SCP_BYTES, m_ptr->SCP_OFFSET,
(vir_bytes) m_ptr->SCP_ADDRESS, access);
}
/*===========================================================================*
* do_vsafecopy *
*===========================================================================*/
PUBLIC int do_vsafecopy(struct proc * caller, message * m_ptr)
{
static struct vscp_vec vec[SCPVEC_NR];
static struct vir_addr src, dst;
int r, i, els;
size_t bytes;
/* Set vector copy parameters. */
src.proc_nr_e = caller->p_endpoint;
src.offset = (vir_bytes) m_ptr->VSCP_VEC_ADDR;
src.segment = dst.segment = D;
dst.proc_nr_e = KERNEL;
dst.offset = (vir_bytes) vec;
/* No. of vector elements. */
els = m_ptr->VSCP_VEC_SIZE;
bytes = els * sizeof(struct vscp_vec);
/* Obtain vector of copies. */
if((r=virtual_copy_vmcheck(caller, &src, &dst, bytes)) != OK)
return r;
/* Perform safecopies. */
for(i = 0; i < els; i++) {
int access;
endpoint_t granter;
if(vec[i].v_from == SELF) {
access = CPF_WRITE;
granter = vec[i].v_to;
} else if(vec[i].v_to == SELF) {
access = CPF_READ;
granter = vec[i].v_from;
} else {
printf("vsafecopy: %d: element %d/%d: no SELF found\n",
caller->p_endpoint, i, els);
return EINVAL;
}
/* Do safecopy for this element. */
if((r=safecopy(caller, granter, caller->p_endpoint,
vec[i].v_gid, D, D,
vec[i].v_bytes, vec[i].v_offset,
vec[i].v_addr, access)) != OK) {
return r;
}
}
return OK;
}