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-rw-r--r--grp/grp-merge.c200
1 files changed, 200 insertions, 0 deletions
diff --git a/grp/grp-merge.c b/grp/grp-merge.c
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index 0000000000..24898b05d0
--- /dev/null
+++ b/grp/grp-merge.c
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+/* 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)