[kernel-hardening] Re: [PATCH v6 0/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
From: Alan Cox <hidden>
Date: 2017-05-30 21:54:37
Also in:
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From: Alan Cox <hidden>
Date: 2017-05-30 21:54:37
Also in:
lkml
quoted
So tty stuff should under a tty capabilities.(last reply on this) Currently capabilities.7 says * employ the TIOCSTI ioctl(2) to insert characters into the input queue of a terminal other than the caller's controlling terminal; for CAP_SYS_ADMIN. So you can create a new CAP_SYS_TIOCSSTI if you like, and offer a patch where *both* CAP_SYS_ADMIN and CAP_SYS_ADMIN suffice. Again, see CAP_SYSLOG for a prior example.
Even then it wouldn't be useful because the attacker can use every other interface in the tty layer, many of which you can't magic away behind a capability bit. And the applications would need changing to use the feature - at which point any theoretical broken apps can instead be fixed to use a pty/tty pair and actually fix the real problem. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html