| /* Group merging implementation. |
| Copyright (C) 2016-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <errno.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <grp.h> |
| #include <grp-merge.h> |
| |
| #define BUFCHECK(size) \ |
| ({ \ |
| do \ |
| { \ |
| if (c + (size) > buflen) \ |
| { \ |
| free (members); \ |
| return ERANGE; \ |
| } \ |
| } \ |
| while (0); \ |
| }) |
| |
| int |
| __copy_grp (const struct group srcgrp, const size_t buflen, |
| struct group *destgrp, char *destbuf, char **endptr) |
| { |
| size_t i; |
| size_t c = 0; |
| size_t len; |
| size_t memcount; |
| char **members = NULL; |
| |
| /* Copy the GID. */ |
| destgrp->gr_gid = srcgrp.gr_gid; |
| |
| /* Copy the name. */ |
| len = strlen (srcgrp.gr_name) + 1; |
| BUFCHECK (len); |
| memcpy (&destbuf[c], srcgrp.gr_name, len); |
| destgrp->gr_name = &destbuf[c]; |
| c += len; |
| |
| /* Copy the password. */ |
| len = strlen (srcgrp.gr_passwd) + 1; |
| BUFCHECK (len); |
| memcpy (&destbuf[c], srcgrp.gr_passwd, len); |
| destgrp->gr_passwd = &destbuf[c]; |
| c += len; |
| |
| /* Count all of the members. */ |
| for (memcount = 0; srcgrp.gr_mem[memcount]; memcount++) |
| ; |
| |
| /* Allocate a temporary holding area for the pointers to the member |
| contents, including space for a NULL-terminator. */ |
| members = malloc (sizeof (char *) * (memcount + 1)); |
| if (members == NULL) |
| return ENOMEM; |
| |
| /* Copy all of the group members to destbuf and add a pointer to each of |
| them into the 'members' array. */ |
| for (i = 0; srcgrp.gr_mem[i]; i++) |
| { |
| len = strlen (srcgrp.gr_mem[i]) + 1; |
| BUFCHECK (len); |
| memcpy (&destbuf[c], srcgrp.gr_mem[i], len); |
| members[i] = &destbuf[c]; |
| c += len; |
| } |
| members[i] = NULL; |
| |
| /* Align for pointers. We can't simply align C because we need to |
| align destbuf[c]. */ |
| if ((((uintptr_t)destbuf + c) & (__alignof__(char **) - 1)) != 0) |
| { |
| uintptr_t mis_align = ((uintptr_t)destbuf + c) & (__alignof__(char **) - 1); |
| c += __alignof__(char **) - mis_align; |
| } |
| |
| /* Copy the pointers from the members array into the buffer and assign them |
| to the gr_mem member of destgrp. */ |
| destgrp->gr_mem = (char **) &destbuf[c]; |
| len = sizeof (char *) * (memcount + 1); |
| BUFCHECK (len); |
| memcpy (&destbuf[c], members, len); |
| c += len; |
| free (members); |
| members = NULL; |
| |
| /* Save the count of members at the end. */ |
| BUFCHECK (sizeof (size_t)); |
| memcpy (&destbuf[c], &memcount, sizeof (size_t)); |
| c += sizeof (size_t); |
| |
| if (endptr) |
| *endptr = destbuf + c; |
| return 0; |
| } |
| libc_hidden_def (__copy_grp) |
| |
| /* Check that the name, GID and passwd fields match, then |
| copy in the gr_mem array. */ |
| int |
| __merge_grp (struct group *savedgrp, char *savedbuf, char *savedend, |
| size_t buflen, struct group *mergegrp, char *mergebuf) |
| { |
| size_t c, i, len; |
| size_t savedmemcount; |
| size_t memcount; |
| size_t membersize; |
| char **members = NULL; |
| |
| /* We only support merging members of groups with identical names and |
| GID values. If we hit this case, we need to overwrite the current |
| buffer with the saved one (which is functionally equivalent to |
| treating the new lookup as NSS_STATUS_NOTFOUND). */ |
| if (mergegrp->gr_gid != savedgrp->gr_gid |
| || strcmp (mergegrp->gr_name, savedgrp->gr_name)) |
| return __copy_grp (*savedgrp, buflen, mergegrp, mergebuf, NULL); |
| |
| /* Get the count of group members from the last sizeof (size_t) bytes in the |
| mergegrp buffer. */ |
| savedmemcount = *(size_t *) (savedend - sizeof (size_t)); |
| |
| /* Get the count of new members to add. */ |
| for (memcount = 0; mergegrp->gr_mem[memcount]; memcount++) |
| ; |
| |
| /* Create a temporary array to hold the pointers to the member values from |
| both the saved and merge groups. */ |
| membersize = savedmemcount + memcount + 1; |
| members = malloc (sizeof (char *) * membersize); |
| if (members == NULL) |
| return ENOMEM; |
| |
| /* Copy in the existing member pointers from the saved group |
| Note: this is not NULL-terminated yet. */ |
| memcpy (members, savedgrp->gr_mem, sizeof (char *) * savedmemcount); |
| |
| /* Back up into the savedbuf until we get back to the NULL-terminator of the |
| group member list. (This means walking back savedmemcount + 1 (char *) pointers |
| and the member count value. |
| The value of c is going to be the used length of the buffer backed up by |
| the member count and further backed up by the size of the pointers. */ |
| c = savedend - savedbuf |
| - sizeof (size_t) |
| - sizeof (char *) * (savedmemcount + 1); |
| |
| /* Add all the new group members, overwriting the old NULL-terminator while |
| adding the new pointers to the temporary array. */ |
| for (i = 0; mergegrp->gr_mem[i]; i++) |
| { |
| len = strlen (mergegrp->gr_mem[i]) + 1; |
| BUFCHECK (len); |
| memcpy (&savedbuf[c], mergegrp->gr_mem[i], len); |
| members[savedmemcount + i] = &savedbuf[c]; |
| c += len; |
| } |
| /* Add the NULL-terminator. */ |
| members[savedmemcount + memcount] = NULL; |
| |
| /* Align for pointers. We can't simply align C because we need to |
| align savedbuf[c]. */ |
| if ((((uintptr_t)savedbuf + c) & (__alignof__(char **) - 1)) != 0) |
| { |
| uintptr_t mis_align = ((uintptr_t)savedbuf + c) & (__alignof__(char **) - 1); |
| c += __alignof__(char **) - mis_align; |
| } |
| |
| /* Copy the member array back into the buffer after the member list and free |
| the member array. */ |
| savedgrp->gr_mem = (char **) &savedbuf[c]; |
| len = sizeof (char *) * membersize; |
| BUFCHECK (len); |
| memcpy (&savedbuf[c], members, len); |
| c += len; |
| |
| free (members); |
| members = NULL; |
| |
| /* Finally, copy the results back into mergebuf, since that's the buffer |
| that we were provided by the caller. */ |
| return __copy_grp (*savedgrp, buflen, mergegrp, mergebuf, NULL); |
| } |
| libc_hidden_def (__merge_grp) |