Data::ReqRep::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O_EXCL or O_NOFOLLOW. The segment is created in reqrep.h with open(path, O_RDWR | O_CREAT, 0666), for both the request-reply and the integer-variant segments. The mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable). O_NOFOLLOW is absent, so a symlink planted at the path is followed, and O_EXCL is absent, so the open silently uses a pre-planted
Data::ReqRep::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O_EXCL or O_NOFOLLOW.
The segment is created in reqrep.h with open(path, O_RDWR | O_CREAT, 0666), for both the request-reply and the integer-variant segments. The mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable). O_NOFOLLOW is absent, so a symlink planted at the path is followed, and O_EXCL is absent, so the open silently uses a pre-planted file instead of failing.
A "Shared" segment naturally lives in a shared directory such as /tmp or /dev/shm, where any local user can read the IPC payloads stored in the world-readable segment, and a pre-planted file or symlink at the path lets a local attacker win a pre-creation race or redirect the open.
为什么是这个 VPI(可解释·实验性)
VPI 计算依据
| 影响度(默认值（无数据）) | 55.00 |
| 利用信号(无额外利用信号) | ×1.00 |
| VPI | 55.00 |
VPI 公式 vpi-v1