diff options
| author | Michal Srb <msrb@suse.com> | 2017-10-26 09:48:13 +0200 |
|---|---|---|
| committer | Matthieu Herrb <matthieu@herrb.eu> | 2017-11-25 11:45:41 +0100 |
| commit | 7b377456f95d2ec3ead40f4fb74ea620191f88c8 (patch) | |
| tree | 490711446aa5e24235d047a6dbebd44aba0084f6 | |
| parent | d82dfe25491c599f650b2ad868772c3b8e6ba7bc (diff) | |
Open files with O_NOFOLLOW. (CVE-2017-16611)
A non-privileged X client can instruct X server running under root to open any
file by creating own directory with "fonts.dir", "fonts.alias" or any font file
being a symbolic link to any other file in the system. X server will then open
it. This can be issue with special files such as /dev/watchdog.
Reviewed-by: Matthieu Herrb <matthieu@herrb.eu>
| -rw-r--r-- | src/fontfile/dirfile.c | 25 | ||||
| -rw-r--r-- | src/fontfile/fileio.c | 5 |
2 files changed, 26 insertions, 4 deletions
diff --git a/src/fontfile/dirfile.c b/src/fontfile/dirfile.c index 04cfa40..2802980 100644 --- a/src/fontfile/dirfile.c +++ b/src/fontfile/dirfile.c @@ -42,6 +42,7 @@ in this Software without prior written authorization from The Open Group. #include <stdio.h> #include <sys/types.h> #include <sys/stat.h> +#include <fcntl.h> #include <errno.h> #include <limits.h> @@ -61,8 +62,9 @@ FontFileReadDirectory (const char *directory, FontDirectoryPtr *pdir) char dir_file[MAXFONTFILENAMELEN]; char dir_path[MAXFONTFILENAMELEN]; char *ptr; - FILE *file; - int count, + FILE *file = 0; + int file_fd, + count, num_fonts, status; struct stat statb; @@ -92,7 +94,14 @@ FontFileReadDirectory (const char *directory, FontDirectoryPtr *pdir) if (dir_file[strlen(dir_file) - 1] != '/') strcat(dir_file, "/"); strcat(dir_file, FontDirFile); +#ifndef WIN32 + file_fd = open(dir_file, O_RDONLY | O_NOFOLLOW); + if (file_fd >= 0) { + file = fdopen(file_fd, "rt"); + } +#else file = fopen(dir_file, "rt"); +#endif if (file) { #ifndef WIN32 if (fstat (fileno(file), &statb) == -1) @@ -262,7 +271,8 @@ ReadFontAlias(char *directory, Bool isFile, FontDirectoryPtr *pdir) char alias[MAXFONTNAMELEN]; char font_name[MAXFONTNAMELEN]; char alias_file[MAXFONTFILENAMELEN]; - FILE *file; + int file_fd; + FILE *file = 0; FontDirectoryPtr dir; int token; char *lexToken; @@ -280,7 +290,16 @@ ReadFontAlias(char *directory, Bool isFile, FontDirectoryPtr *pdir) strcat(alias_file, "/"); strcat(alias_file, FontAliasFile); } + +#ifndef WIN32 + file_fd = open(alias_file, O_RDONLY | O_NOFOLLOW); + if (file_fd >= 0) { + file = fdopen(file_fd, "rt"); + } +#else file = fopen(alias_file, "rt"); +#endif + if (!file) return ((errno == ENOENT) ? Successful : BadFontPath); if (!dir) diff --git a/src/fontfile/fileio.c b/src/fontfile/fileio.c index 074ebcb..05374b4 100644 --- a/src/fontfile/fileio.c +++ b/src/fontfile/fileio.c @@ -40,6 +40,9 @@ in this Software without prior written authorization from The Open Group. #ifndef O_CLOEXEC #define O_CLOEXEC 0 #endif +#ifndef O_NOFOLLOW +#define O_NOFOLLOW 0 +#endif FontFilePtr FontFileOpen (const char *name) @@ -48,7 +51,7 @@ FontFileOpen (const char *name) int len; BufFilePtr raw, cooked; - fd = open (name, O_BINARY|O_CLOEXEC); + fd = open (name, O_BINARY|O_CLOEXEC|O_NOFOLLOW); if (fd < 0) return 0; raw = BufFileOpenRead (fd); |