info-vax (12/31/82)
>From EPS@JPL-VAX Fri Dec 31 04:45:39 1982 Mail-From: ARPANET host JPL-VAX rcvd at 30-Dec-82 1735-PST To: Info-VAX@SRI-CSL Remailed-Date: 30 Dec 1982 2320-PST Remailed-From: the tty of Geoffrey S. Goodfellow <Geoff5 at SRI-CSL> Remailed-To: Info-VAX@SRI-CSL: ; An instructor wishes to establish accounts for students in his class. A natural troublemaker, he asks to be able to monitor their usage. A group number is assigned for the exclusive use of this class. The instructor has GROUP and GRPNAM. He wishes "exceptional" access to files in his group. Design and code the new privilege "GRPPRV" that will allow the instructor to have godly influence over his students. ------- F11BACP calls EXE$GETACCESS to validate UIC-based protection. This seems like the logical place to start. Inputs: R0: Address of Access Rights Block +-------------------------------+ | | | Current Privileges | | | +-------------------------------+ | Reserved | +-------------------------------+ | GRP <-UIC-> MEM | +-------------------------------+ R1: Protection of object (bit set ==> access disallowed) +-------------------------------+ | WWWWGGGGOOOOSSSS| +-------------------------------+ R2: Owner UIC of object +-------------------------------+ | GRP <-UIC-> MEM | +-------------------------------+ Outputs: R0: Allowed access (bit set ==> access permitted) +-------------------------------+ | WWWWGGGGOOOOSSSS| +-------------------------------+ EXE$GETACCESS: BBS #PRV$V_BYPASS,(R0),EXE$GETACCESS+49 PUSHL R3 MOVZWL #0F000,R3 MOVZWL B^0E(R0),-(SP) CMPZV #10,#10,R2,(SP)+ BNEQ EXE$GETACCESS+2A INSV #0F,#08,#04,R3 CMPW B^0C(R0),R2 BNEQ EXE$GETACCESS+2A INSV #0F,#04,#04,R3 EXE$GETACCESS+2A: BBS #PRV$V_SYSPRV,(R0),EXE$GETACCESS+3C CMPW L^EXE$GL_SYSUIC,B^0E(R0) BLSSU EXE$GETACCESS+41 INSV #0F,#00,#04,R3 EXE$GETACCESS+41: BICL3 R1,R3,R0 MOVL (SP)+,R3 RSB EXE$GETACCESS+49: MNEGL #01,R0 RSB (Replies to the list. Happy hacking! -=EPS=-)