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CVE-2016-1234: glob: Do not copy d_name field of struct dirent [BZ #19779]
Instead, we store the data we need from the return value of readdir in an object of the new type struct readdir_result. This type is independent of the layout of struct dirent.
This commit is contained in:
Florian Weimer
parent
2faba597ec
commit
5171f3079f
21
ChangeLog
21
ChangeLog
@ -1,3 +1,24 @@
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2016-05-04 Florian Weimer <fweimer@redhat.com>
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[BZ #19779]
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CVE-2016-1234
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Avoid copying names of directory entries.
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* posix/glob.c (DIRENT_MUST_BE, DIRENT_MIGHT_BE_SYMLINK)
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(DIRENT_MIGHT_BE_DIR, CONVERT_D_INO, CONVERT_D_TYPE)
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(CONVERT_DIRENT_DIRENT64, REAL_DIR_ENTRY): Remove macros.
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(struct readdir_result): New type.
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(D_TYPE_TO_RESULT, D_INO_TO_RESULT, READDIR_RESULT_INITIALIZER)
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(GL_READDIR): New macros.
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(readdir_result_might_be_symlink, readdir_result_might_be_dir)
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(convert_dirent, convert_dirent64): New functions.
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(glob_in_dir): Use struct readdir_result. Call convert_dirent or
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convert_dirent64. Adjust references to the readdir result.
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* sysdeps/unix/sysv/linux/i386/glob64.c:
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(convert_dirent, GL_READDIR): Redefine for second file inclusion.
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* posix/bug-glob2.c (LONG_NAME): Define.
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(filesystem): Add LONG_NAME.
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(my_DIR): Increase the size of room_for_dirent.
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2016-05-03 Joseph Myers <joseph@codesourcery.com>
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[BZ #20041]
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4
NEWS
4
NEWS
@ -44,6 +44,10 @@ Security related changes:
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resulting in a stack overflow. getaddrinfo now uses a heap allocation
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instead. Reported by Michael Petlan. (CVE-2016-3706)
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* The glob function suffered from a stack-based buffer overflow when it was
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called with the GLOB_ALTDIRFUNC flag and encountered a long file name.
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Reported by Alexander Cherepanov. (CVE-2016-1234)
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The following bugs are resolved with this release:
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[The release manager will add the list generated by
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@ -40,6 +40,17 @@
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# define PRINTF(fmt, args...)
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#endif
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#define LONG_NAME \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
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"xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
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static struct
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{
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@ -58,6 +69,7 @@ static struct
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{ ".", 3, DT_DIR, 0755 },
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{ "..", 3, DT_DIR, 0755 },
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{ "a", 3, DT_REG, 0644 },
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{ LONG_NAME, 3, DT_REG, 0644 },
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{ "unreadable", 2, DT_DIR, 0111 },
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{ ".", 3, DT_DIR, 0111 },
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{ "..", 3, DT_DIR, 0755 },
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@ -75,7 +87,7 @@ typedef struct
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int level;
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int idx;
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struct dirent d;
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char room_for_dirent[NAME_MAX];
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char room_for_dirent[sizeof (LONG_NAME)];
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} my_DIR;
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223
posix/glob.c
223
posix/glob.c
@ -24,7 +24,9 @@
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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/* Outcomment the following line for production quality code. */
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/* #define NDEBUG 1 */
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@ -73,69 +75,8 @@
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# endif /* HAVE_VMSDIR_H */
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#endif
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/* When used in the GNU libc the symbol _DIRENT_HAVE_D_TYPE is available
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if the `d_type' member for `struct dirent' is available.
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HAVE_STRUCT_DIRENT_D_TYPE plays the same role in GNULIB. */
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#if defined _DIRENT_HAVE_D_TYPE || defined HAVE_STRUCT_DIRENT_D_TYPE
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/* True if the directory entry D must be of type T. */
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# define DIRENT_MUST_BE(d, t) ((d)->d_type == (t))
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/* True if the directory entry D might be a symbolic link. */
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# define DIRENT_MIGHT_BE_SYMLINK(d) \
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((d)->d_type == DT_UNKNOWN || (d)->d_type == DT_LNK)
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/* True if the directory entry D might be a directory. */
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# define DIRENT_MIGHT_BE_DIR(d) \
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((d)->d_type == DT_DIR || DIRENT_MIGHT_BE_SYMLINK (d))
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#else /* !HAVE_D_TYPE */
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# define DIRENT_MUST_BE(d, t) false
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# define DIRENT_MIGHT_BE_SYMLINK(d) true
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# define DIRENT_MIGHT_BE_DIR(d) true
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#endif /* HAVE_D_TYPE */
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/* If the system has the `struct dirent64' type we use it internally. */
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#if defined _LIBC && !defined COMPILE_GLOB64
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# if (defined POSIX || defined WINDOWS32) && !defined __GNU_LIBRARY__
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# define CONVERT_D_INO(d64, d32)
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# else
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# define CONVERT_D_INO(d64, d32) \
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(d64)->d_ino = (d32)->d_ino;
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# endif
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# ifdef _DIRENT_HAVE_D_TYPE
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# define CONVERT_D_TYPE(d64, d32) \
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(d64)->d_type = (d32)->d_type;
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# else
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# define CONVERT_D_TYPE(d64, d32)
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# endif
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# define CONVERT_DIRENT_DIRENT64(d64, d32) \
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strcpy ((d64)->d_name, (d32)->d_name); \
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CONVERT_D_INO (d64, d32) \
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CONVERT_D_TYPE (d64, d32)
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#endif
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#if (defined POSIX || defined WINDOWS32) && !defined __GNU_LIBRARY__
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/* Posix does not require that the d_ino field be present, and some
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systems do not provide it. */
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# define REAL_DIR_ENTRY(dp) 1
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#else
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# define REAL_DIR_ENTRY(dp) (dp->d_ino != 0)
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#endif /* POSIX */
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#include <stdlib.h>
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#include <string.h>
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/* NAME_MAX is usually defined in <dirent.h> or <limits.h>. */
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#include <limits.h>
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#ifndef NAME_MAX
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# define NAME_MAX (sizeof (((struct dirent *) 0)->d_name))
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#endif
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#include <alloca.h>
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#ifdef _LIBC
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@ -180,8 +121,111 @@
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static const char *next_brace_sub (const char *begin, int flags) __THROWNL;
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/* A representation of a directory entry which does not depend on the
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layout of struct dirent, or the size of ino_t. */
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struct readdir_result
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{
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const char *name;
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# if defined _DIRENT_HAVE_D_TYPE || defined HAVE_STRUCT_DIRENT_D_TYPE
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uint8_t type;
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# endif
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bool skip_entry;
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};
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# if defined _DIRENT_HAVE_D_TYPE || defined HAVE_STRUCT_DIRENT_D_TYPE
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/* Initializer based on the d_type member of struct dirent. */
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# define D_TYPE_TO_RESULT(source) (source)->d_type,
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/* True if the directory entry D might be a symbolic link. */
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static bool
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readdir_result_might_be_symlink (struct readdir_result d)
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{
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return d.type == DT_UNKNOWN || d.type == DT_LNK;
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}
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/* True if the directory entry D might be a directory. */
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static bool
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readdir_result_might_be_dir (struct readdir_result d)
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{
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return d.type == DT_DIR || readdir_result_might_be_symlink (d);
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}
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# else /* defined _DIRENT_HAVE_D_TYPE || defined HAVE_STRUCT_DIRENT_D_TYPE */
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# define D_TYPE_TO_RESULT(source)
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/* If we do not have type information, symbolic links and directories
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are always a possibility. */
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static bool
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readdir_result_might_be_symlink (struct readdir_result d)
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{
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return true;
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}
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static bool
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readdir_result_might_be_dir (struct readdir_result d)
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{
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return true;
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}
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# endif /* defined _DIRENT_HAVE_D_TYPE || defined HAVE_STRUCT_DIRENT_D_TYPE */
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# if (defined POSIX || defined WINDOWS32) && !defined __GNU_LIBRARY__
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/* Initializer for skip_entry. POSIX does not require that the d_ino
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field be present, and some systems do not provide it. */
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# define D_INO_TO_RESULT(source) false,
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# else
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# define D_INO_TO_RESULT(source) (source)->d_ino == 0,
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# endif
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/* Construct an initializer for a struct readdir_result object from a
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struct dirent *. No copy of the name is made. */
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#define READDIR_RESULT_INITIALIZER(source) \
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{ \
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source->d_name, \
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D_TYPE_TO_RESULT (source) \
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D_INO_TO_RESULT (source) \
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}
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#endif /* !defined _LIBC || !defined GLOB_ONLY_P */
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/* Call gl_readdir on STREAM. This macro can be overridden to reduce
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type safety if an old interface version needs to be supported. */
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#ifndef GL_READDIR
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# define GL_READDIR(pglob, stream) ((pglob)->gl_readdir (stream))
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#endif
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/* Extract name and type from directory entry. No copy of the name is
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made. If SOURCE is NULL, result name is NULL. Keep in sync with
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convert_dirent64 below. */
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static struct readdir_result
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convert_dirent (const struct dirent *source)
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{
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if (source == NULL)
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{
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struct readdir_result result = { NULL, };
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return result;
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}
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struct readdir_result result = READDIR_RESULT_INITIALIZER (source);
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return result;
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}
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#ifndef COMPILE_GLOB64
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/* Like convert_dirent, but works on struct dirent64 instead. Keep in
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sync with convert_dirent above. */
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static struct readdir_result
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convert_dirent64 (const struct dirent64 *source)
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{
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if (source == NULL)
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{
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struct readdir_result result = { NULL, };
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return result;
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}
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struct readdir_result result = READDIR_RESULT_INITIALIZER (source);
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return result;
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}
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#endif
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#ifndef attribute_hidden
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# define attribute_hidden
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#endif
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@ -1538,55 +1582,36 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
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while (1)
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{
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const char *name;
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#if defined _LIBC && !defined COMPILE_GLOB64
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struct dirent64 *d;
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union
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{
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struct dirent64 d64;
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char room [offsetof (struct dirent64, d_name[0])
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+ NAME_MAX + 1];
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}
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d64buf;
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if (__glibc_unlikely (flags & GLOB_ALTDIRFUNC))
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{
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struct dirent *d32 = (*pglob->gl_readdir) (stream);
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if (d32 != NULL)
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{
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CONVERT_DIRENT_DIRENT64 (&d64buf.d64, d32);
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d = &d64buf.d64;
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}
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else
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d = NULL;
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}
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else
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d = __readdir64 (stream);
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struct readdir_result d;
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{
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if (__builtin_expect (flags & GLOB_ALTDIRFUNC, 0))
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d = convert_dirent (GL_READDIR (pglob, stream));
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else
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{
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#ifdef COMPILE_GLOB64
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d = convert_dirent (__readdir (stream));
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#else
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struct dirent *d = (__builtin_expect (flags & GLOB_ALTDIRFUNC, 0)
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? ((struct dirent *)
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(*pglob->gl_readdir) (stream))
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: __readdir (stream));
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d = convert_dirent64 (__readdir64 (stream));
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#endif
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if (d == NULL)
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}
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}
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if (d.name == NULL)
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break;
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if (! REAL_DIR_ENTRY (d))
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if (d.skip_entry)
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continue;
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/* If we shall match only directories use the information
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provided by the dirent call if possible. */
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if ((flags & GLOB_ONLYDIR) && !DIRENT_MIGHT_BE_DIR (d))
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if ((flags & GLOB_ONLYDIR) && !readdir_result_might_be_dir (d))
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continue;
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name = d->d_name;
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if (fnmatch (pattern, name, fnm_flags) == 0)
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if (fnmatch (pattern, d.name, fnm_flags) == 0)
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{
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/* If the file we found is a symlink we have to
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make sure the target file exists. */
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if (!DIRENT_MIGHT_BE_SYMLINK (d)
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|| link_exists_p (dfd, directory, dirlen, name, pglob,
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flags))
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if (!readdir_result_might_be_symlink (d)
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|| link_exists_p (dfd, directory, dirlen, d.name,
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pglob, flags))
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{
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if (cur == names->count)
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{
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@ -1606,7 +1631,7 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
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names = newnames;
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cur = 0;
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}
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names->name[cur] = strdup (d->d_name);
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names->name[cur] = strdup (d.name);
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if (names->name[cur] == NULL)
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goto memory_error;
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++cur;
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@ -1,3 +1,21 @@
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/* Two glob variants with 64-bit support, for dirent64 and __olddirent64.
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Copyright (C) 1998-2016 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <dirent.h>
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#include <glob.h>
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#include <sys/stat.h>
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@ -38,11 +56,15 @@ int __old_glob64 (const char *__pattern, int __flags,
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#undef dirent
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#define dirent __old_dirent64
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#undef GL_READDIR
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# define GL_READDIR(pglob, stream) \
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((struct __old_dirent64 *) (pglob)->gl_readdir (stream))
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#undef __readdir
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#define __readdir(dirp) __old_readdir64 (dirp)
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#undef glob
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#define glob(pattern, flags, errfunc, pglob) \
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__old_glob64 (pattern, flags, errfunc, pglob)
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#define convert_dirent __old_convert_dirent
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#define glob_in_dir __old_glob_in_dir
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#define GLOB_ATTRIBUTE attribute_compat_text_section
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