diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/bindfs.c | 74 |
1 files changed, 42 insertions, 32 deletions
diff --git a/src/bindfs.c b/src/bindfs.c index dd32800..b4a1f5a 100644 --- a/src/bindfs.c +++ b/src/bindfs.c @@ -243,10 +243,11 @@ static int chown_new_file(const char *path, struct fuse_context *fc, int (*chown static int delete_file(const char *path, int (*target_delete_func)(const char *)); /* Apply offsets with overflow checking. */ -static int apply_uid_offset(uid_t *uid); -static int apply_gid_offset(gid_t *gid); -static int unapply_uid_offset(uid_t *uid); -static int unapply_gid_offset(gid_t *gid); +static bool apply_uid_offset(uid_t *uid); +static bool apply_gid_offset(gid_t *gid); +static bool unapply_uid_offset(uid_t *uid); +static bool unapply_gid_offset(gid_t *gid); +static bool bounded_add(int64_t* a, int64_t b, int64_t max); #ifdef __linux__ static size_t round_up_buffer_size_for_direct_io(size_t size); @@ -635,48 +636,57 @@ static int delete_file(const char *path, int (*target_delete_func)(const char *) return 0; } -static int apply_uid_offset(uid_t *uid) { - uid_t result = *uid + (uid_t)settings.uid_offset; - if (0 <= result && result <= UID_T_MAX) { - *uid = result; - return 1; +static bool apply_uid_offset(uid_t *uid) { + int64_t value = (int64_t)*uid; + if (bounded_add(&value, settings.uid_offset, UID_T_MAX)) { + *uid = (uid_t)value; + return true; } else { - DPRINTF("UID %ld overflowed while applying offset", (int64_t)*uid); - return 0; + DPRINTF("UID %ld out of bounds after applying offset", value); + return false; } } -static int apply_gid_offset(gid_t *gid) { - gid_t result = *gid + (gid_t)settings.gid_offset; - if (0 <= result && result <= GID_T_MAX) { - *gid = result; - return 1; +static bool apply_gid_offset(gid_t *gid) { + int64_t value = (int64_t)*gid; + if (bounded_add(&value, settings.gid_offset, GID_T_MAX)) { + *gid = (uid_t)value; + return true; } else { - DPRINTF("GID %ld overflowed while applying offset", (int64_t)*gid); - return 0; + DPRINTF("GID %ld out of bounds after applying offset", value); + return false; } } -static int unapply_uid_offset(uid_t *uid) { - uid_t result = *uid - (uid_t)settings.uid_offset; - if (0 <= result && result <= UID_T_MAX) { - *uid = result; - return 1; +static bool unapply_uid_offset(uid_t *uid) { + int64_t value = (int64_t)*uid; + if (bounded_add(&value, -settings.uid_offset, UID_T_MAX)) { + *uid = (uid_t)value; + return true; } else { - DPRINTF("UID %ld underflowed while applying offset", (int64_t)*uid); - return 0; + DPRINTF("UID %ld out of bounds after unapplying offset", value); + return false; } } -static int unapply_gid_offset(gid_t *gid) { - gid_t result = *gid - (gid_t)settings.gid_offset; - if (0 <= result && result <= GID_T_MAX) { - *gid = result; - return 1; +static bool unapply_gid_offset(gid_t *gid) { + int64_t value = (int64_t)*gid; + if (bounded_add(&value, -settings.gid_offset, GID_T_MAX)) { + *gid = (uid_t)value; + return true; } else { - DPRINTF("GID %ld underflowed while applying offset", (int64_t)*gid); - return 0; + DPRINTF("GID %ld out of bounds after unapplying offset", value); + return false; + } +} + +static bool bounded_add(int64_t* a, int64_t b, int64_t max) { + int64_t result; + if (!__builtin_add_overflow(*a, b, &result) && 0 <= result && result <= max) { + *a = result; + return true; } + return false; } #ifdef __linux__ |