diff options
Diffstat (limited to 'runtime/POSIX/fd.c')
| -rw-r--r-- | runtime/POSIX/fd.c | 32 |
1 files changed, 9 insertions, 23 deletions
diff --git a/runtime/POSIX/fd.c b/runtime/POSIX/fd.c index be13a40b..b41d4e32 100644 --- a/runtime/POSIX/fd.c +++ b/runtime/POSIX/fd.c @@ -106,32 +106,18 @@ mode_t umask(mode_t mask) { /* Returns 1 if the process has the access rights specified by 'flags' - to the file with stat 's'. Returns 0 otherwise*/ + to the file with stat 's', and returns 0 otherwise. + We allow access if any user has access to the file, so we ignore + s->st_uid / geteuid() and s->st_gid / getegid(). */ static int has_permission(int flags, struct stat64 *s) { - int write_access, read_access; mode_t mode = s->st_mode; - - if (flags & O_RDONLY || flags & O_RDWR) - read_access = 1; - else read_access = 0; - - if (flags & O_WRONLY || flags & O_RDWR) - write_access = 1; - else write_access = 0; - - /* XXX: We don't worry about process uid and gid for now. - We allow access if any user has access to the file. */ -#if 0 - uid_t uid = s->st_uid; - uid_t euid = geteuid(); - gid_t gid = s->st_gid; - gid_t egid = getegid(); -#endif - - if (read_access && ((mode & S_IRUSR) | (mode & S_IRGRP) | (mode & S_IROTH))) - return 0; + int read_request = ((flags & O_RDONLY) | (flags & O_RDWR)) ? 1 : 0; + int write_request = ((flags & O_WRONLY) | (flags & O_RDWR)) ? 1 : 0; - if (write_access && !((mode & S_IWUSR) | (mode & S_IWGRP) | (mode & S_IWOTH))) + /* It is important to do this check using only bitwise operators so that we + return 0 a single time in symbolic execution mode. */ + if ((read_request & !((mode & S_IRUSR) | (mode & S_IRGRP) | (mode & S_IROTH))) | + (write_request & !((mode & S_IWUSR) | (mode & S_IWGRP) | (mode & S_IWOTH)))) return 0; return 1; |