+2023-05-15 Paul Eggert <eggert@cs.ucla.edu>
+
+ file-has-acl: improve port to Fedora 39
+ Problem reported by Ondrej Valousek in:
+ https://lists.gnu.org/r/bug-gnulib/2023-05/msg00078.html
+ * lib/file-has-acl.c: Include minmax.h.
+ [USE_ACL && HAVE_LINUX_XATTR_H && HAVE_LISTXATTR]: Include stdckdint.h.
+ (file_has_acl) [USE_ACL && HAVE_LINUX_XATTR_H && HAVE_LISTXATTR]:
+ If the file has NFSv4 ACLs, ignore any POSIX ACLs, for Fedora 39.
+ Return a bit faster when listxattr returns 0.
+ Don’t loop forever if an attacker is fiddling with ACLs.
+ * modules/file-has-acl (Depends-on): Add minmax, stdckdint.
+
2023-05-15 Bruno Haible <bruno@clisp.org>
Work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82283 .
#include "acl-internal.h"
+#include "minmax.h"
+
#if USE_ACL && HAVE_LINUX_XATTR_H && HAVE_LISTXATTR
+# include <stdckdint.h>
# include <string.h>
# include <arpa/inet.h>
# include <sys/xattr.h>
&& errno == ERANGE)
{
free (heapbuf);
- listbufsize = listxattr (name, NULL, 0);
- if (listbufsize < 0)
- return -1;
- if (SIZE_MAX < listbufsize)
+ ssize_t newsize = listxattr (name, NULL, 0);
+ if (newsize <= 0)
+ return newsize;
+
+ /* Grow LISTBUFSIZE to at least NEWSIZE. Grow it by a
+ nontrivial amount too, to defend against denial of
+ service by an adversary that fiddles with ACLs. */
+ bool overflow = ckd_add (&listbufsize, listbufsize, listbufsize >> 1);
+ listbufsize = MAX (listbufsize, newsize);
+ if (overflow || SIZE_MAX < listbufsize)
{
errno = ENOMEM;
return -1;
}
+
listbuf = heapbuf = malloc (listbufsize);
if (!listbuf)
return -1;
}
+ /* In Fedora 39, a file can have both NFSv4 and POSIX ACLs,
+ but if it has an NFSv4 ACL that's the one that matters.
+ In earlier Fedora the two types of ACLs were mutually exclusive.
+ Attempt to work correctly on both kinds of systems. */
+ bool nfsv4_acl
+ = 0 < listsize && have_xattr (XATTR_NAME_NFSV4_ACL, listbuf, listsize);
int ret
- = (listsize < 0 ? -1
- : (have_xattr (XATTR_NAME_POSIX_ACL_ACCESS, listbuf, listsize)
+ = (listsize <= 0 ? listsize
+ : (nfsv4_acl
+ || have_xattr (XATTR_NAME_POSIX_ACL_ACCESS, listbuf, listsize)
|| (S_ISDIR (sb->st_mode)
&& have_xattr (XATTR_NAME_POSIX_ACL_DEFAULT,
listbuf, listsize))));
- bool nfsv4_acl_but_no_posix_acl
- = ret == 0 && have_xattr (XATTR_NAME_NFSV4_ACL, listbuf, listsize);
free (heapbuf);
- /* If there is an NFSv4 ACL but no POSIX ACL, follow up with a
- getxattr syscall to see whether the NFSv4 ACL is nontrivial. */
- if (nfsv4_acl_but_no_posix_acl)
+ /* If there is an NFSv4 ACL, follow up with a getxattr syscall
+ to see whether the NFSv4 ACL is nontrivial. */
+ if (nfsv4_acl)
{
ret = getxattr (name, XATTR_NAME_NFSV4_ACL,
stackbuf.xattr, sizeof stackbuf.xattr);