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The directory package as implemented in AFS-2 allocates space for each directory entry as a DirEntry struct followed by 0-8 contiguous DirXEntry structs, as needed. This is implemented by: - afs_dir_NameBlobs calculates the number of blocks needed - FindBlobs allocates and returns index of entry - afs_dir_GetBlob returns pointer to 1st DirEntry struct After this, we populate DirEntry (and any contiguous DirXEntry blocks) with open code. Most existing code writes the entry's name via a string copy operation to DirEntry->name, which is only 16 bytes long. Therefore, for dir entry names that are 16 bytes or longer, OpenAFS routinely does string copies that look like buffer overruns. This has not previously caused problems because the OpenAFS code has arranged for a sufficiently large amount of contiguous memory to be available. However, this remains undefined behavior in the C abstract virtual machine; thus compilers are not required to produce safe operation. Recent changes in the OpenAFS build chain have made this approach no longer viable: 1) Linux 6.5 commit df8fc4e934c12b 'kbuild: Enable -fstrict-flex-arrays=3' modified the hardening of several kernel string operations when running with CONFIG_FORTIFY_SOURCE=y. 2) gcc 13 commit 79a89108dd352cd9288f5de35481b1280c7588a5 '__builtin_dynamic_object_size: Recognize builtin' provides some enhancements to _builtin_object_size. The Linux commit above will now use these when the kernel is built with gcc 13. When OpenAFS is built under Linux 6.5 or higher and gcc 13 or higher, the hardened strlcpy will BUG for directory entry names longer than 16 characters. Since there are multiple places where OpenAFS writes directory names, there are several symptoms that may manifest. However, the first one is usually a kernel BUG at cache manager initialization if running with afsd -dynroot _and_ there are any cell names 15 characters or longer in the client CellServDB. (A 15-character cellname reaches the 16 character limit when -dyrnoot adds the RW mountpoint ".<cellname>".) Address this by using flexible arrays (standardized with C99). A flexible array is a variable-length array that is declared with no size at all, e.g., name[]. Create an autoconf test to determine whether the compiler supports flexible arrays. Create a new struct DirEntryFlex. If the compiler supports flexible arrays, define name[]; otherwise retain the name[16] definition. Whenever we write a directory name, use DirEntryFlex so that any hardening will be satisfied that there is sufficient space for the name. However, the actual guarantee that this is true is still provided by the OpenAFS directory routines mentioned above - all of these remain unchanged. The DirEntry struct remains unchanged for continued use in OpenAFS, as well as for any out-of-tree users of the directory package. Change-Id: I6da5c6c295f051be90017084e5b3a3ef24d1271f Reviewed-on: https://gerrit.openafs.org/15573 Tested-by: BuildBot <buildbot@rampaginggeek.com> Reviewed-by: Cheyenne Wills <cwills@sinenomine.net> Reviewed-by: Benjamin Kaduk <kaduk@mit.edu> Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
84 lines
1.7 KiB
Plaintext
84 lines
1.7 KiB
Plaintext
dnl This file contains the common configuration code which would
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dnl otherwise be duplicated between configure and configure-libafs.
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dnl
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dnl NB: Because this code is a macro, references to positional shell
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dnl parameters must be done like $[]1 instead of $1
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AC_DEFUN([OPENAFS_CONFIGURE_COMMON],[
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OPENAFS_AUTOHEADER_TOP
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OPENAFS_AUTOHEADER_BOTTOM
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AC_CANONICAL_HOST
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SRCDIR_PARENT=`pwd`
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#BOZO_SAVE_CORES pam
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OPENAFS_OPTIONS
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OPENAFS_DOC
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dnl Checks for UNIX variants.
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AC_SEARCH_LIBS([strerror],[cposix])
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dnl Various compiler setup.
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AC_TYPE_PID_T
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AC_TYPE_SIZE_T
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dnl Checks for programs.
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AC_PROG_INSTALL
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AC_PROG_LN_S
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AC_PROG_RANLIB
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AC_PROG_YACC
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OPENAFS_LEX
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dnl Checks
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OPENAFS_FORCE_ABS_INSTALL
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OPENAFS_CHECK_BIGENDIAN
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OPENAFS_PRINTF_TAKES_Z_LEN
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OPENAFS_OSTYPE
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OPENAFS_SYSNAME
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OPENAFS_OSCONF
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OPENAFS_LINUX_CHECKS
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OPENAFS_C_ATOMIC_CHECKS
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OPENAFS_SOCKET_CHECKS
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OPENAFS_LIBRARY_CHECKS
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AC_CHECK_RESOLV_RETRANS
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OPENAFS_SOCKOPT_CHECK
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OPENAFS_PTHREAD_CHECKS
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HOST_CPU="$host_cpu"
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OPENAFS_BSD_CHECKS
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OPENAFS_OPTION_TESTS
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OPENAFS_TIVOLI_TESTS
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OPENAFS_HEADER_CHECKS
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OPENAFS_MEMBER_CHECKS
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OPENAFS_LIBINTL_CHECKS
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OPENAFS_MORE_OPTION_TESTS
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OPENAFS_FUNCTION_CHECKS
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OPENAFS_ROKEN
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OPENAFS_HCRYPTO
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OPENAFS_CURSES
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OPENAFS_C_ATTRIBUTE
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OPENAFS_C_PRAGMA
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OPENAFS_C_FLEXIBLE_ARRAY
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OPENAFS_MORE_ROKEN_CHECKS
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OPENAFS_NETDB_CHECKS
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OPENAFS_ROKEN_HEADERS
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OPENAFS_BSWAP_CHECKS
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OPENAFS_PIO_CHECKS
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OPENAFS_REGEX_CHECKS
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OPENAFS_MORE_PTHREAD_CHECKS
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OPENAFS_TYPE_CHECKS
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RRA_HEADER_PAM_CONST
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OPENAFS_DIRECTORY_PATHS
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OPENAFS_YET_MORE_OPTION_TESTS
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OPENAFS_OUTPUT_VARIABLES
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OPENAFS_FUSE
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OPENAFS_SWIG
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OPENAFS_TOPDIRS
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OPENAFS_CROSSTOOLS
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OPENAFS_LINT
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OPENAFS_CRYPT_CHECKS
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OPENAFS_C_STRUCT_LABEL_CHECK
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OPENAFS_DIRENT_CHECKS
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OPENAFS_SYS_RESOURCE_CHECKS
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OPENAFS_UUID_CHECKS
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OPENAFS_CTF_TOOLS_CHECKS
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])
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