kernel/system/do_safecopy.c

   1 /* The kernel call implemented in this file:
   2  *   m_type:    SYS_SAFECOPYFROM or SYS_SAFECOPYTO or SYS_VSAFECOPY
   3  *
   4  * The parameters for this kernel call are:
   5  *      SCP_FROM_TO     other endpoint
   6  *      SCP_GID         grant id
   7  *      SCP_OFFSET      offset within granted space
   8  *      SCP_ADDRESS     address in own address space
   9  *      SCP_BYTES       bytes to be copied
  10  *
  11  * For the vectored variant (do_vsafecopy):
  12  *      VSCP_VEC_ADDR   address of vector
  13  *      VSCP_VEC_SIZE   number of significant elements in vector
  14  */
  15
  16 #include <assert.h>
  17
  18 #include "kernel/system.h"
  19 #include "kernel.h"
  20
  21 #define MAX_INDIRECT_DEPTH 5    /* up to how many indirect grants to follow? */
  22
  23 #define MEM_TOP 0xFFFFFFFFUL
  24
  25 static int safecopy(struct proc *, endpoint_t, endpoint_t,
  26         cp_grant_id_t, size_t, vir_bytes, vir_bytes, int);
  27
  28 #define HASGRANTTABLE(gr) \
  29         (priv(gr) && priv(gr)->s_grant_table)
  30
  31 /*===========================================================================*
  32  *                              verify_grant                                 *
  33  *===========================================================================*/
  34 int verify_grant(granter, grantee, grant, bytes, access,
  35         offset_in, offset_result, e_granter)
  36 endpoint_t granter, grantee;    /* copyee, copyer */
  37 cp_grant_id_t grant;            /* grant id */
  38 vir_bytes bytes;                /* copy size */
  39 int access;                     /* direction (read/write) */
  40 vir_bytes offset_in;            /* copy offset within grant */
  41 vir_bytes *offset_result;       /* copy offset within virtual address space */
  42 endpoint_t *e_granter;          /* new granter (magic grants) */
  43 {
  44         static cp_grant_t g;
  45         static int proc_nr;
  46         static const struct proc *granter_proc;
  47         int depth = 0;
  48
  49         do {
  50                 /* Get granter process slot (if valid), and check range of
  51                  * grant id.
  52                  */
  53                 if(!isokendpt(granter, &proc_nr) ) {
  54                         printf(
  55                         "grant verify failed: invalid granter %d\n", (int) granter);
  56                         return(EINVAL);
  57                 }
  58                 if(!GRANT_VALID(grant)) {
  59                         printf(
  60                         "grant verify failed: invalid grant %d\n", (int) grant);
  61                         return(EINVAL);
  62                 }
  63                 granter_proc = proc_addr(proc_nr);
  64
  65                 /* If there is no priv. structure, or no grant table in the
  66                  * priv. structure, or the grant table in the priv. structure
  67                  * is too small for the grant, return EPERM.
  68                  */
  69                 if(!HASGRANTTABLE(granter_proc)) {
  70                         printf(
  71                         "grant verify failed: granter %d has no grant table\n",
  72                         granter);
  73                         return(EPERM);
  74                 }
  75
  76                 if(priv(granter_proc)->s_grant_entries <= grant) {
  77                                 printf(
  78                                 "verify_grant: grant verify failed in ep %d "
  79                                 "proc %d: grant %d out of range "
  80                                 "for table size %d\n",
  81                                         granter, proc_nr, grant,
  82                                         priv(granter_proc)->s_grant_entries);
  83                         return(EPERM);
  84                 }
  85
  86                 /* Copy the grant entry corresponding to this id to see what it
  87                  * looks like. If it fails, hide the fact that granter has
  88                  * (presumably) set an invalid grant table entry by returning
  89                  * EPERM, just like with an invalid grant id.
  90                  */
  91                 if(data_copy(granter,
  92                         priv(granter_proc)->s_grant_table + sizeof(g)*grant,
  93                         KERNEL, (vir_bytes) &g, sizeof(g)) != OK) {
  94                         printf(
  95                         "verify_grant: grant verify: data_copy failed\n");
  96                         return EPERM;
  97                 }
  98
  99                 /* Check validity. */
 100                 if((g.cp_flags & (CPF_USED | CPF_VALID)) !=
 101                         (CPF_USED | CPF_VALID)) {
 102                         printf(
 103                         "verify_grant: grant failed: invalid (%d flags 0x%lx)\n",
 104                                 grant, g.cp_flags);
 105                         return EPERM;
 106                 }
 107
 108                 /* The given grant may be an indirect grant, that is, a grant
 109                  * that provides permission to use a grant given to the
 110                  * granter (i.e., for which it is the grantee). This can lead
 111                  * to a chain of indirect grants which must be followed back.
 112                  */
 113                 if((g.cp_flags & CPF_INDIRECT)) {
 114                         /* Stop after a few iterations. There may be a loop. */
 115                         if (depth == MAX_INDIRECT_DEPTH) {
 116                                 printf(
 117                                         "verify grant: indirect grant verify "
 118                                         "failed: exceeded maximum depth\n");
 119                                 return ELOOP;
 120                         }
 121                         depth++;
 122
 123                         /* Verify actual grantee. */
 124                         if(g.cp_u.cp_indirect.cp_who_to != grantee &&
 125                                 grantee != ANY &&
 126                                 g.cp_u.cp_indirect.cp_who_to != ANY) {
 127                                 printf(
 128                                         "verify_grant: indirect grant verify "
 129                                         "failed: bad grantee\n");
 130                                 return EPERM;
 131                         }
 132
 133                         /* Start over with new granter, grant, and grantee. */
 134                         grantee = granter;
 135                         granter = g.cp_u.cp_indirect.cp_who_from;
 136                         grant = g.cp_u.cp_indirect.cp_grant;
 137                 }
 138         } while(g.cp_flags & CPF_INDIRECT);
 139
 140         /* Check access of grant. */
 141         if(((g.cp_flags & access) != access)) {
 142                 printf(
 143         "verify_grant: grant verify failed: access invalid; want 0x%x, have 0x%x\n",
 144                         access, g.cp_flags);
 145                 return EPERM;
 146         }
 147
 148         if((g.cp_flags & CPF_DIRECT)) {
 149                 /* Don't fiddle around with grants that wrap, arithmetic
 150                  * below may be confused.
 151                  */
 152                 if(MEM_TOP - g.cp_u.cp_direct.cp_len + 1 <
 153                         g.cp_u.cp_direct.cp_start) {
 154                         printf(
 155                 "verify_grant: direct grant verify failed: len too long\n");
 156                         return EPERM;
 157                 }
 158
 159                 /* Verify actual grantee. */
 160                 if(g.cp_u.cp_direct.cp_who_to != grantee && grantee != ANY
 161                         && g.cp_u.cp_direct.cp_who_to != ANY) {
 162                         printf(
 163                 "verify_grant: direct grant verify failed: bad grantee\n");
 164                         return EPERM;
 165                 }
 166
 167                 /* Verify actual copy range. */
 168                 if((offset_in+bytes < offset_in) ||
 169                     offset_in+bytes > g.cp_u.cp_direct.cp_len) {
 170                         printf(
 171                 "verify_grant: direct grant verify failed: bad size or range. "
 172                 "granted %d bytes @ 0x%lx; wanted %d bytes @ 0x%lx\n",
 173                                 g.cp_u.cp_direct.cp_len,
 174                                 g.cp_u.cp_direct.cp_start,
 175                                 bytes, offset_in);
 176                         return EPERM;
 177                 }
 178
 179                 /* Verify successful - tell caller what address it is. */
 180                 *offset_result = g.cp_u.cp_direct.cp_start + offset_in;
 181                 *e_granter = granter;
 182         } else if(g.cp_flags & CPF_MAGIC) {
 183                 /* Currently, it is hardcoded that only FS may do
 184                  * magic grants.
 185                  */
 186                 if(granter != VFS_PROC_NR) {
 187                         printf(
 188                 "verify_grant: magic grant verify failed: granter (%d) "
 189                 "is not FS (%d)\n", granter, VFS_PROC_NR);
 190                         return EPERM;
 191                 }
 192
 193                 /* Verify actual grantee. */
 194                 if(g.cp_u.cp_magic.cp_who_to != grantee && grantee != ANY
 195                         && g.cp_u.cp_direct.cp_who_to != ANY) {
 196                         printf(
 197                 "verify_grant: magic grant verify failed: bad grantee\n");
 198                         return EPERM;
 199                 }
 200
 201                 /* Verify actual copy range. */
 202                 if((offset_in+bytes < offset_in) ||
 203                     offset_in+bytes > g.cp_u.cp_magic.cp_len) {
 204                         printf(
 205                 "verify_grant: magic grant verify failed: bad size or range. "
 206                 "granted %d bytes @ 0x%lx; wanted %d bytes @ 0x%lx\n",
 207                                 g.cp_u.cp_magic.cp_len,
 208                                 g.cp_u.cp_magic.cp_start,
 209                                 bytes, offset_in);
 210                         return EPERM;
 211                 }
 212
 213                 /* Verify successful - tell caller what address it is. */
 214                 *offset_result = g.cp_u.cp_magic.cp_start + offset_in;
 215                 *e_granter = g.cp_u.cp_magic.cp_who_from;
 216         } else {
 217                 printf(
 218                 "verify_grant: grant verify failed: unknown grant type\n");
 219                 return EPERM;
 220         }
 221
 222         return OK;
 223 }
 224
 225 /*===========================================================================*
 226  *                              safecopy                                     *
 227  *===========================================================================*/
 228 static int safecopy(caller, granter, grantee, grantid, bytes,
 229         g_offset, addr, access)
 230 struct proc * caller;
 231 endpoint_t granter, grantee;
 232 cp_grant_id_t grantid;
 233 size_t bytes;
 234 vir_bytes g_offset, addr;
 235 int access;                     /* CPF_READ for a copy from granter to grantee, CPF_WRITE
 236                                  * for a copy from grantee to granter.
 237                                  */
 238 {
 239         static struct vir_addr v_src, v_dst;
 240         static vir_bytes v_offset;
 241         endpoint_t new_granter, *src, *dst;
 242         struct proc *granter_p;
 243         int r;
 244 #if PERF_USE_COW_SAFECOPY
 245         vir_bytes size;
 246 #endif
 247
 248         if(granter == NONE || grantee == NONE) {
 249                 printf("safecopy: nonsense processes\n");
 250                 return EFAULT;
 251         }
 252
 253         /* See if there is a reasonable grant table. */
 254         if(!(granter_p = endpoint_lookup(granter))) return EINVAL;
 255         if(!HASGRANTTABLE(granter_p)) {
 256                 printf(
 257                 "safecopy failed: granter %d has no grant table\n", granter);
 258                 return(EPERM);
 259         }
 260
 261         /* Decide who is src and who is dst. */
 262         if(access & CPF_READ) {
 263                 src = &granter;
 264                 dst = &grantee;
 265         } else {
 266                 src = &grantee;
 267                 dst = &granter;
 268         }
 269
 270         /* Verify permission exists. */
 271         if((r=verify_grant(granter, grantee, grantid, bytes, access,
 272             g_offset, &v_offset, &new_granter)) != OK) {
 273                         printf(
 274                 "grant %d verify to copy %d->%d by %d failed: err %d\n",
 275                                 grantid, *src, *dst, grantee, r);
 276                 return r;
 277         }
 278
 279         /* verify_grant() can redirect the grantee to someone else,
 280          * meaning the source or destination changes.
 281          */
 282         granter = new_granter;
 283
 284         /* Now it's a regular copy. */
 285         v_src.proc_nr_e = *src;
 286         v_dst.proc_nr_e = *dst;
 287
 288         /* Now the offset in virtual addressing is known in 'offset'.
 289          * Depending on the access, this is the source or destination
 290          * address.
 291          */
 292         if(access & CPF_READ) {
 293                 v_src.offset = v_offset;
 294                 v_dst.offset = (vir_bytes) addr;
 295         } else {
 296                 v_src.offset = (vir_bytes) addr;
 297                 v_dst.offset = v_offset;
 298         }
 299
 300         /* Do the regular copy. */
 301         return virtual_copy_vmcheck(caller, &v_src, &v_dst, bytes);
 302 }
 303
 304 /*===========================================================================*
 305  *                              do_safecopy_to                               *
 306  *===========================================================================*/
 307 int do_safecopy_to(struct proc * caller, message * m_ptr)
 308 {
 309         return safecopy(caller, m_ptr->SCP_FROM_TO, caller->p_endpoint,
 310                 (cp_grant_id_t) m_ptr->SCP_GID,
 311                 m_ptr->SCP_BYTES, m_ptr->SCP_OFFSET,
 312                 (vir_bytes) m_ptr->SCP_ADDRESS, CPF_WRITE);
 313 }
 314
 315 /*===========================================================================*
 316  *                              do_safecopy_from                             *
 317  *===========================================================================*/
 318 int do_safecopy_from(struct proc * caller, message * m_ptr)
 319 {
 320         return safecopy(caller, m_ptr->SCP_FROM_TO, caller->p_endpoint,
 321                 (cp_grant_id_t) m_ptr->SCP_GID,
 322                 m_ptr->SCP_BYTES, m_ptr->SCP_OFFSET,
 323                 (vir_bytes) m_ptr->SCP_ADDRESS, CPF_READ);
 324 }
 325
 326 /*===========================================================================*
 327  *                              do_vsafecopy                                 *
 328  *===========================================================================*/
 329 int do_vsafecopy(struct proc * caller, message * m_ptr)
 330 {
 331         static struct vscp_vec vec[SCPVEC_NR];
 332         static struct vir_addr src, dst;
 333         int r, i, els;
 334         size_t bytes;
 335
 336         /* Set vector copy parameters. */
 337         src.proc_nr_e = caller->p_endpoint;
 338         assert(src.proc_nr_e != NONE);
 339         src.offset = (vir_bytes) m_ptr->VSCP_VEC_ADDR;
 340         dst.proc_nr_e = KERNEL;
 341         dst.offset = (vir_bytes) vec;
 342
 343         /* No. of vector elements. */
 344         els = m_ptr->VSCP_VEC_SIZE;
 345         bytes = els * sizeof(struct vscp_vec);
 346
 347         /* Obtain vector of copies. */
 348         if((r=virtual_copy_vmcheck(caller, &src, &dst, bytes)) != OK)
 349                 return r;
 350
 351         /* Perform safecopies. */
 352         for(i = 0; i < els; i++) {
 353                 int access;
 354                 endpoint_t granter;
 355                 if(vec[i].v_from == SELF) {
 356                         access = CPF_WRITE;
 357                         granter = vec[i].v_to;
 358                 } else if(vec[i].v_to == SELF) {
 359                         access = CPF_READ;
 360                         granter = vec[i].v_from;
 361                 } else {
 362                         printf("vsafecopy: %d: element %d/%d: no SELF found\n",
 363                                 caller->p_endpoint, i, els);
 364                         return EINVAL;
 365                 }
 366
 367                 /* Do safecopy for this element. */
 368                 if((r=safecopy(caller, granter, caller->p_endpoint,
 369                         vec[i].v_gid,
 370                         vec[i].v_bytes, vec[i].v_offset,
 371                         vec[i].v_addr, access)) != OK) {
 372                         return r;
 373                 }
 374         }
 375
 376         return OK;
 377 }
 378