1.\" $NetBSD: kauth.9,v 1.32 2006/11/04 10:47:37 elad Exp $ 2.\" 3.\" Copyright (c) 2005, 2006 Elad Efrat <elad@NetBSD.org> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by Elad Efrat. 17.\" 4. The name of the author may not be used to endorse or promote products 18.\" derived from this software without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 21.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 24.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd November 4, 2006 32.Dt KAUTH 9 33.Os 34.Sh NAME 35.Nm kauth 36.Nd kernel authorization framework 37.Sh SYNOPSIS 38.In sys/kauth.h 39.Sh DESCRIPTION 40.Nm , 41or kernel authorization, is the subsystem managing all authorization requests 42inside the kernel. 43It manages user credentials and rights, and can be used 44to implement a system-wide security policy. 45It allows external modules to plug-in the authorization process. 46.Pp 47.Nm 48introduces some new concepts, namely 49.Dq scopes 50and 51.Dq listeners , 52which will be detailed together with other useful information for kernel 53developers in this document. 54.Ss Types 55Some 56.Nm 57types include the following: 58.Bl -tag 59.It kauth_cred_t 60Representing credentials that can be associated with an object. 61Includes user- and group-ids (real, effective, and save) as well as group 62membership information. 63.It kauth_scope_t 64Describes a scope. 65.It kauth_listener_t 66Describes a listener. 67.El 68.Ss Terminology 69.Nm 70operates in various 71.Dq scopes , 72each scope holding a group of 73.Dq listeners . 74.Pp 75Each listener works as a callback for when an authorization request within the 76scope is made. 77When such a request is made, all listeners on the scope are passed common 78information such as the credentials of the request context, an identifier for 79the requested operation, and possibly other information as well. 80.Pp 81Every listener examines the passed information and returns its decision 82regarding the requested operation. 83It can either allow, deny, or defer the operation -- in which case, the 84decision is left to the other listeners. 85.Pp 86For an operation to be allowed, all listeners must not return any deny 87or defer decisions. 88.Pp 89Scopes manage listeners that operate in the same aspect of the system. 90.Ss Kernel Programming Interface 91.Nm 92exports a KPI that allows developers both of 93.Nx 94and third-party products to authorize requests, access and modify credentials, 95create and remove scopes and listeners, and perform other miscellaneous operations on 96credentials. 97.Ss Authorization Requests 98.Nm 99provides a single authorization request routine, which all authorization 100requests go through. 101This routine dispatches the request to the listeners of the appropriate scope, 102together with four optional user-data variables, and returns the augmented 103result. 104.Pp 105It is declared as 106.Pp 107.Ft int Fn kauth_authorize_action "kauth_scope_t scope" "kauth_cred_t cred" \ 108"kauth_action_t op" "void *arg0" "void *arg1" "void *arg2" "void *arg3" 109.Pp 110An authorization request can return one of two possible values. 111Zero indicates success -- the operation is allowed; 112.Er EPERM 113(see 114.Xr errno 2 ) 115indicates failure -- the operation is denied. 116.Pp 117Each scope has its own authorization wrapper, to make it easy to call from various 118places by eliminating the need to specify the scope and/or cast values. 119The authorization wrappers are detailed in each scope's section. 120.Ss Generic Scope 121The generic scope, 122.Dq org.netbsd.kauth.generic , 123manages generic authorization requests in the kernel. 124.Pp 125The authorization wrapper for this scope is declared as 126.Pp 127.Ft int Fn kauth_authorize_generic "kauth_cred_t cred" "kauth_action_t op" \ 128"void *arg0" 129.Pp 130The following operations are available for this scope: 131.Bl -tag 132.It Dv KAUTH_GENERIC_ISSUSER 133Checks whether the credentials belong to the super-user. 134.Pp 135Using this request is strongly discouraged and should only be done as a 136temporary place-holder, as it is breaking the separation between the 137interface for authorization requests from the back-end implementation. 138.It Dv KAUTH_GENERIC_CANSEE 139Checks whether an object with one set of credentials can access 140information about another object, possibly with a different set of 141credentials. 142.Pp 143.Ar arg0 144contains the credentials of the object looked at. 145.Pp 146This request should be issued only in cases where generic credentials 147check is required; otherwise it is recommended to use the object-specific 148routines. 149.El 150.Ss System Scope 151The system scope, 152.Dq org.netbsd.kauth.system , 153manages authorization requests affecting the entire system. 154.Pp 155The authorization wrapper for this scope is declared as 156.Pp 157.Ft int Fn kauth_authorize_system "kauth_cred_t cred" \ 158"kauth_action_t op" "enum kauth_system_req req" "void *arg1" "void *arg2" \ 159"void *arg3" 160.Pp 161The following requests are available for this scope: 162.Bl -tag 163.It Dv KAUTH_SYSTEM_ACCOUNTING 164Check if enabling/disabling accounting allowed. 165.It Dv KAUTH_SYSTEM_CHROOT 166.Ar req 167can be any of the following: 168.Bl -tag 169.It Dv KAUTH_REQ_SYSTEM_CHROOT_CHROOT 170Check if calling 171.Xr chroot 2 172is allowed. 173.It Dv KAUTH_REQ_SYSTEM_CHROOT_FCHROOT 174Check if calling 175.Xr fchroot 2 176is allowed. 177.El 178.It Dv KAUTH_SYSTEM_DEBUG 179This request concentrates several debugging-related operations. 180.Ar req 181can be any of the following: 182.Bl -tag 183.It Dv KAUTH_REQ_SYSTEM_DEBUG_IPKDB 184Check if using 185.Xr ipkdb 4 186is allowed. 187.El 188.It Dv KAUTH_SYSTEM_FILEHANDLE 189Check if filehandle operations allowed. 190.It Dv KAUTH_SYSTEM_LKM 191Check if an LKM request is allowed. 192.Pp 193.Ar arg1 194is the command. 195.It Dv KAUTH_SYSTEM_MKNOD 196Check if creating devices is allowed. 197.It Dv KAUTH_SYSTEM_REBOOT 198Check if rebooting is allowed. 199.It Dv KAUTH_SYSTEM_SETIDCORE 200Check if changing coredump settings for set-id processes is allowed. 201.It Dv KAUTH_SYSTEM_SWAPCTL 202Check if privileged 203.Xr swapctl 2 204requests are allowed. 205.It Dv KAUTH_SYSTEM_SYSCTL 206This requests operations related to 207.Xr sysctl 9 . 208.Ar req 209indicates the specific request and can be one of the following: 210.Bl -tag 211.It Dv KAUTH_REQ_SYSTEM_SYSCTL_ADD 212Check if adding a 213.Xr sysctl 9 214node is allowed. 215.It Dv KAUTH_REQ_SYSTEM_SYSCTL_DELETE 216Check if deleting a 217.Xr sysctl 9 218node is allowed. 219.It Dv KAUTH_REQ_SYSTEM_SYSCTL_DESC 220Check if adding description to a 221.Xr sysctl 9 222node is allowed. 223.It Dv KAUTH_REQ_SYSTEM_SYSCTL_PRVT 224Check if accessing private 225.Xr sysctl 9 226nodes is allowed. 227.El 228.It Dv KAUTH_SYSTEM_TIME 229This request groups time-related operations. 230.Ar req 231can be any of the following: 232.Bl -tag 233.It Dv KAUTH_REQ_SYSTEM_TIME_ADJTIME 234Check if changing the time using 235.Xr adjtime 2 236is allowed. 237.It Dv KAUTH_REQ_SYSTEM_TIME_BACKWARDS 238Check if setting the time backwards is allowed. 239.It Dv KAUTH_REQ_SYSTEM_TIME_NTPADJTIME 240Check if setting the time using 241.Xr ntp_adjtime 2 242is allowed. 243.It Dv KAUTH_REQ_SYSTEM_TIME_SYSTEM 244Check if changing the time (usually via 245.Xr settimeofday 2 ) 246is allowed. 247.It Dv KAUTH_REQ_SYSTEM_TIME_RTCOFFSET 248Check if changing the RTC offset is allowed. 249.El 250.El 251.Ss Process Scope 252The process scope, 253.Dq org.netbsd.kauth.process , 254manages authorization requests related to processes in the system. 255.Pp 256The authorization wrapper for this scope is declared as 257.Pp 258.Ft int Fn kauth_authorize_process "kauth_cred_t cred" \ 259"kauth_action_t op" "struct proc *p" "void *arg1" "void *arg2" \ 260"void *arg3" 261.Pp 262The following operations are available for this scope: 263.Bl -tag 264.It Dv KAUTH_PROCESS_CANSIGNAL 265Checks whether an object with one set of credentials can post signals 266to another process. 267.Pp 268.Ar p 269is the process the signal is being posted to, and 270.Ar arg1 271is the signal number. 272.It Dv KAUTH_PROCESS_CANSEE 273Checks whether an object with one set of credentials can access 274information about another process, possibly with a different set of 275credentials. 276.It Dv KAUTH_PROCESS_CORENAME 277Checks whether the coredump name for the process 278.Ar p 279can be changed. 280.It Dv KAUTH_PROCESS_RESOURCE 281Groups authorization requests related to resource management. 282.Ar arg0 283indicates the sub-action, and can be one of the following: 284.Bl -tag 285.It Dv KAUTH_REQ_PROCESS_RESOURCE_NICE 286Checks whether the 287.Em nice 288value of 289.Ar p 290can be changed to 291.Ar arg2 . 292.It Dv KAUTH_REQ_PROCESS_RESOURCE_RLIMIT 293Checks whether the 294.Em rlimit 295value for 296.Ar arg3 297in 298.Ar p 299can be set to 300.Ar arg2 . 301.El 302.It Dv KAUTH_PROCESS_SETID 303Check if changing the user- or group-ids, groups, or login-name for 304.Ar p 305is allowed. 306.El 307.Ss Network Scope 308The network scope, 309.Dq org.netbsd.kauth.network , 310manages networking-related authorization requests in the kernel. 311.Pp 312The authorization wrapper for this scope is declared as 313.Pp 314.Ft int Fn kauth_authorize_network "kauth_cred_t cred" "kauth_action_t op" \ 315"enum kauth_network_req req" "void *arg1" "void *arg2" "void *arg3" 316.Pp 317The following operations are available for this scope: 318.Bl -tag 319.It Dv KAUTH_NETWORK_ALTQ 320Checks if an ALTQ operation is allowed. 321.Pp 322.Ar req 323indicates the ALTQ subsystem in question, and can be one of the following: 324.Pp 325.Bl -tag -compact 326.It Dv KAUTH_REQ_NETWORK_ALTQ_AFMAP 327.It Dv KAUTH_REQ_NETWORK_ALTQ_BLUE 328.It Dv KAUTH_REQ_NETWORK_ALTQ_CBQ 329.It Dv KAUTH_REQ_NETWORK_ALTQ_CDNR 330.It Dv KAUTH_REQ_NETWORK_ALTQ_CONF 331.It Dv KAUTH_REQ_NETWORK_ALTQ_FIFOQ 332.It Dv KAUTH_REQ_NETWORK_ALTQ_HFSC 333.It Dv KAUTH_REQ_NETWORK_ALTQ_JOBS 334.It Dv KAUTH_REQ_NETWORK_ALTQ_PRIQ 335.It Dv KAUTH_REQ_NETWORK_ALTQ_RED 336.It Dv KAUTH_REQ_NETWORK_ALTQ_RIO 337.It Dv KAUTH_REQ_NETWORK_ALTQ_WFQ 338.El 339.It Dv KAUTH_NETWORK_BIND 340Checks if a 341.Xr bind 2 342request is allowed. 343.Pp 344.Ar req 345allows to indicate the type of the request to structure listeners and callers 346easier. 347Supported request types: 348.Bl -tag 349.It Dv KAUTH_REQ_NETWORK_BIND_PRIVPORT 350Checks if binding to a privileged/reserved port is allowed. 351.El 352.It Dv KAUTH_NETWORK_FIREWALL 353Checks if firewall-related operations are allowed. 354.Pp 355.Ar req 356indicates the sub-action, and can be one of the following: 357.Bl -tag 358.It Dv KAUTH_REQ_NETWORK_FIREWALL_FW 359Modification of packet filtering rules. 360.It Dv KAUTH_REQ_NETWORK_FIREWALL_NAT 361Modification of NAT rules. 362.El 363.It Dv KAUTH_NETWORK_INTERFACE 364Checks if network interface-related operations are allowed. 365.Pp 366.Ar arg1 367is (optionally) the 368.Ft struct ifnet * 369associated with the interface. 370.Ar arg2 371is (optionally) an 372.Ft int 373describing the interface-specific operation. 374.Ar arg3 375is (optionally) a pointer to the interface-specific request structure. 376.Ar req 377indicates the sub-action, and can be one of the following: 378.Bl -tag 379.It Dv KAUTH_REQ_NETWORK_INTERFACE_GET 380Check if retrieving information from the device is allowed. 381.It Dv KAUTH_REQ_NETWORK_INTERFACE_GETPRIV 382Check if retrieving privileged information from the device is allowed. 383.It Dv KAUTH_REQ_NETWORK_INTERFACE_SET 384Check if setting parameters on the device is allowed. 385.It Dv KAUTH_REQ_NETWORK_INTERFACE_SETPRIV 386Check if setting privileged parameters on the device is allowed. 387.El 388.Pp 389Note that unless the 390.Ft struct ifnet * 391for the interface was passed in 392.Ar arg1 , 393there's no way to tell what structure 394.Ar arg3 395is. 396.It Dv KAUTH_NETWORK_FORWSRCRT 397Checks whether status of forwarding of source-routed packets can be modified 398or not. 399.It Dv KAUTH_NETWORK_ROUTE 400Checks if a routing-related request is allowed. 401.Pp 402.Ar arg1 403is the 404.Ft struct rt_msghdr * 405for the request. 406.It Dv KAUTH_NETWORK_SOCKET 407Checks if a socket related operation is allowed. 408.Pp 409.Ar req 410allows to indicate the type of the request to structure listeners and callers 411easier. 412Supported request types: 413.Bl -tag 414.It Dv KAUTH_REQ_NETWORK_SOCKET_RAWSOCK 415Checks if opening a raw socket is allowed. 416.It Dv KAUTH_REQ_NETWORK_SOCKET_OPEN 417Checks if opening a socket is allowed. 418.Ar arg1 , arg2 , 419and 420.Ar arg3 421are all 422.Ft int 423parameters describing the domain, socket type, and protocol, 424respectively. 425.It Dv KAUTH_REQ_NETWORK_SOCKET_CANSEE 426Checks if looking at the socket passed is allowed. 427.Pp 428.Ar arg1 429is a 430.Ft struct socket * 431describing the socket. 432.El 433.El 434.Ss Machine-dependent Scope 435The machine-dependent (machdep) scope, 436.Dq org.netbsd.kauth.machdep , 437manages machine-dependent authorization requests in the kernel. 438.Pp 439The authorization wrapper for this scope is declared as 440.Pp 441.Ft int Fn kauth_authorize_machdep "kauth_cred_t cred" "kauth_action_t op" \ 442"enum kauth_machdep_req req" "void *arg1" "void *arg2" "void *arg3" 443.Pp 444In this scope, 445.Ar req 446always indicates the machine for the request. 447Below is the list of available request hierarchy. 448.Bl -tag 449.It Dv KAUTH_MACHDEP_X86 450The request is x86 specific. 451.Pp 452Available requests as 453.Ar arg1 454are: 455.Bl -tag 456.It Dv KAUTH_REQ_MACHDEP_X86_IOPL 457Checks if IOPL is allowed to be modified. 458.It Dv KAUTH_REQ_MACHDEP_X86_IOPERM 459Checks if IOPERM is allowed to be modified. 460.It Dv KAUTH_REQ_MACHDEP_X86_MTRR_SET 461Checks if the MTRR can be set. 462.El 463.It Dv KAUTH_MACHDEP_X86_64 464The request is x86-64 specific. 465.Pp 466Available requests as 467.Ar arg1 468are: 469.Bl -tag 470.It Dv KAUTH_REQ_MACHDEP_X86_64_MTRR_GET 471Check if MTRR values can be retrieved. 472.El 473.El 474.Ss Device Scope 475The device scope, 476.Dq org.netbsd.kauth.device , 477manages authorization requests related to devices on the system. 478Devices can be, for example, terminals, tape drives, and any other hardware. 479Network devices specifically are handled by the 480.Em network 481scope. 482.Pp 483This scope provides authorization wrappers for various device types. 484.Pp 485.Ft int Fn kauth_authorize_device_tty "kauth_cred_t cred" "kauth_action_t op" \ 486"struct tty *tty" 487.Pp 488Authorizes requests for 489.Em terminal devices 490on the system. 491The third argument, 492.Ar tty , 493is the terminal device in question. 494It is passed to the listener as 495.Ar arg0 . 496The second argument, 497.Ar op , 498is the action and can be one of the following: 499.Bl -tag 500.It Dv KAUTH_DEVICE_TTY_OPEN 501Open the terminal device pointed to by 502.Ar tty . 503.It Dv KAUTH_DEVICE_TTY_PRIVSET 504Set privileged settings on the terminal device pointed to by 505.Ar tty . 506.El 507.Pp 508.Ft int Fn kauth_authorize_device_spec "kauth_cred_t cred" \ 509"enum kauth_device_req req" "struct vnode *vp" 510.Pp 511Authorizes requests for 512.Em special files , 513usually disk devices, but also direct memory access, on the system. 514.Pp 515It passes 516.Dq KAUTH_DEVICE_RAWIO_SPEC 517as the action to the listener, and accepts two arguments. 518.Ar req , 519passed to the listener as 520.Ar arg0 , 521is access requested, and can be one of 522.Dq KAUTH_REQ_DEVICE_RAWIO_SPEC_READ , 523.Dq KAUTH_REQ_DEVICE_RAWIO_SPEC_WRITE , 524or 525.Dq KAUTH_REQ_DEVICE_RAWIO_SPEC_RW , 526representing read, write, or both read/write access respectively. 527.Ar vp 528is the vnode of the special file in question, and is passed to the listener as 529.Ar arg1 . 530.Pp 531Keep in mind that it is the responsibility of the security model developer to 532check whether the underlying device is a disk or the system memory, using 533.Fn iskmemdev : 534.Bd -literal -offset indent 535if ((vp-\*[Gt]v_type == VCHR) \*[Am]\*[Am] 536 iskmemdev(vp-\*[Gt]v_un.vu_specinfo-\*[Gt]si_rdev)) 537 /* system memory access */ 538.Ed 539.Pp 540.Ft int Fn kauth_authorize_device_passthru "kauth_cred_t cred" "dev_t dev" \ 541"void *data" 542.Pp 543Authorizes hardware 544.Em passthru 545requests, or user commands passed directly to the hardware. 546These have the potential of resulting in direct disk and/or memory access. 547.Pp 548It passes 549.Dq KAUTH_DEVICE_RAWIO_PASSTHRU 550as the action to the listener, and accepts two arguments. 551.Ar dev , 552passed as 553.Ar arg1 554to the listener, is the device for which the request is made, and 555.Ar data , 556passed as 557.Ar arg2 558to the listener, is device-specific data that may be associated with the 559request. 560.El 561.Ss Credentials Accessors and Mutators 562.Nm 563has a variety of accessor and mutator routines to handle 564.Ft kauth_cred_t 565objects. 566.Pp 567The following routines can be used to access and modify the user- and 568group-ids in a 569.Ft kauth_cred_t : 570.Bl -tag 571.It Ft uid_t Fn kauth_cred_getuid "kauth_cred_t cred" 572Returns the real user-id from 573.Ar cred . 574.It Ft uid_t Fn kauth_cred_geteuid "kauth_cred_t cred" 575Returns the effective user-id from 576.Ar cred . 577.It Ft uid_t Fn kauth_cred_getsvuid "kauth_cred_t cred" 578Returns the saved user-id from 579.Ar cred . 580.It Ft void Fn kauth_cred_setuid "kauth_cred_t cred" "uid_t uid" 581Sets the real user-id in 582.Ar cred 583to 584.Ar uid . 585.It Ft void Fn kauth_cred_seteuid "kauth_cred_t cred" "uid_t uid" 586Sets the effective user-id in 587.Ar cred 588to 589.Ar uid . 590.It Ft void Fn kauth_cred_setsvuid "kauth_cred_t cred" "uid_t uid" 591Sets the saved user-id in 592.Ar cred 593to 594.Ar uid . 595.It Ft gid_t Fn kauth_cred_getgid "kauth_cred_t cred" 596Returns the real group-id from 597.Ar cred . 598.It Ft gid_t Fn kauth_cred_getegid "kauth_cred_t cred" 599Returns the effective group-id from 600.Ar cred . 601.It Ft gid_t Fn kauth_cred_getsvgid "kauth_cred_t cred" 602Returns the saved group-id from 603.Ar cred . 604.It Ft void Fn kauth_cred_setgid "kauth_cred_t cred" "gid_t gid" 605Sets the real group-id in 606.Ar cred 607to 608.Ar gid . 609.It Ft void Fn kauth_cred_setegid "kauth_cred_t cred" "gid_t gid" 610Sets the effective group-id in 611.Ar cred 612to 613.Ar gid . 614.It Ft void Fn kauth_cred_setsvgid "kauth_cred_t cred" "gid_t gid" 615Sets the saved group-id in 616.Ar cred 617to 618.Ar gid . 619.It Ft u_int Fn kauth_cred_getrefcnt "kauth_cred_t cred" 620Return the reference count for 621.Ar cred . 622.El 623.Pp 624The following routines can be used to access and modify the group 625list in a 626.Ft kauth_cred_t : 627.Bl -tag 628.It Ft int Fn kauth_cred_ismember_gid "kauth_cred_t cred" "gid_t gid" \ 629"int *resultp" 630Checks if the group-id 631.Ar gid 632is a member in the group list of 633.Ar cred . 634.Pp 635If it is, 636.Ar resultp 637will be set to one, otherwise, to zero. 638.Pp 639The return value is an error code, or zero for success. 640.It Ft u_int Fn kauth_cred_ngroups "kauth_cred_t cred" 641Return the number of groups in the group list of 642.Ar cred . 643.It Ft int Fn kauth_cred_group "kauth_cred_t cred" "u_int idx" 644Return the group-id of the group at index 645.Ar idx 646in the group list of 647.Ar cred . 648.It Ft int Fn kauth_cred_setgroups "kauth_cred_t cred" "gid_t *groups" \ 649"size_t ngroups" "uid_t gmuid" 650Copy 651.Ar ngroups 652groups from array pointed to by 653.Ar groups 654to the group list in 655.Ar cred , 656adjusting the number of groups in 657.Ar cred 658appropriately. 659.Pp 660Any groups remaining will be set to an invalid value. 661.Pp 662.Ar gmuid 663is unused for now, and to maintain interface compatibility with the Darwin 664KPI. 665.It Ft int Fn kauth_cred_getgroups "kauth_cred_t cred" "gid_t *groups" \ 666"size_t ngroups" 667Copy 668.Ar ngroups 669groups from the group list in 670.Ar cred 671to the buffer pointed to by 672.Ar groups . 673.Pp 674The number of groups in 675.Ar cred 676will be returned. 677.El 678.Ss Credentials Inheritance and Reference Counting 679.Nm 680provides a KPI for handling a 681.Ft kauth_cred_t 682in shared credentials situations and credential inheritance. 683.Pp 684When a 685.Ft kauth_cred_t 686is first allocated, its reference count is set to 1. 687However, with time, its reference count can grow as more objects (processes, 688LWPs, files, etc.) reference it. 689One such case is during a 690.Xr fork 2 691where the child process and its LWPs inherit the credentials of the parent. 692.Pp 693To prevent freeing a 694.Ft kauth_cred_t 695while it is still referenced, the following routines are available to maintain 696its reference count: 697.Bl -tag 698.It Ft void Fn kauth_cred_hold "kauth_cred_t cred" 699Increases reference count to 700.Ar cred 701by one. 702.It Ft void Fn kauth_cred_free "kauth_cred_t cred" 703Decreases the reference count to 704.Ar cred 705by one. 706.Pp 707If the reference count dropped to zero, the memory used by 708.Ar cred 709will be returned back to the memory pool. 710.El 711.Ss Credentials Memory Management 712Data-structures for credentials, listeners, and scopes are allocated from 713memory pools managed by the 714.Xr pool 9 715subsystem. 716.Pp 717The 718.Ft kauth_cred_t 719objects have their own memory management routines: 720.Bl -tag 721.It Ft kauth_cred_t Fn kauth_cred_alloc "void" 722Allocates a new 723.Ft kauth_cred_t , 724initializes its lock, and sets its reference count to one. 725.El 726.Ss Conversion Routines 727Sometimes it might be necessary to convert a 728.Ft kauth_cred_t 729to userland's view of credentials, a 730.Ft struct uucred , 731or vice versa. 732.Pp 733The following routines are available for these cases: 734.Bl -tag 735.It Ft void Fn kauth_uucred_to_cred "kauth_cred_t cred" "const struct uucred *uucred" 736Convert userland's view of credentials to a 737.Ft kauth_cred_t . 738.Pp 739This includes effective user- and group-ids, a number of groups, and a group 740list. 741The reference count is set to one. 742.Pp 743Note that 744.Nm 745will try to copy as many groups as can be held inside a 746.Ft kauth_cred_t . 747.It Ft void Fn kauth_cred_to_uucred "struct uucred *uucred" "const kauth_cred_t cred" 748Convert 749.Ft kauth_cred_t 750to userland's view of credentials. 751.Pp 752This includes effective user- and group-ids, a number of groups, and a group 753list. 754.Pp 755Note that 756.Nm 757will try to copy as many groups as can be held inside a 758.Ft struct uucred . 759.It Ft int Fn kauth_cred_uucmp "kauth_cred_t cred" "struct uucred *uucred" 760Compares 761.Ar cred 762with the userland credentials in 763.Ar uucred . 764.Pp 765Common values that will be compared are effective user- and group-ids, and 766the group list. 767.El 768.Ss Miscellaneous Routines 769Other routines provided by 770.Nm 771are: 772.Bl -tag 773.It Ft void Fn kauth_cred_clone "kauth_cred_t cred1" "kauth_cred_t cred2" 774Clone credentials from 775.Ar cred1 776to 777.Ar cred2 , 778except for the lock and reference count. 779.Pp 780.It Ft kauth_cred_t Fn kauth_cred_dup "kauth_cred_t cred" 781Duplicate 782.Ar cred . 783.Pp 784What this routine does is call 785.Fn kauth_cred_alloc 786followed by a call to 787.Fn kauth_cred_clone . 788.It Ft kauth_cred_t Fn kauth_cred_copy "kauth_cred_t cred" 789Works like 790.Fn kauth_cred_dup , 791except for a few differences. 792.Pp 793If 794.Ar cred 795already has a reference count of one, it will be returned. 796Otherwise, a new 797.Ft kauth_cred_t 798will be allocated and the credentials from 799.Ar cred 800will be cloned to it. 801Last, a call to 802.Fn kauth_cred_free 803for 804.Ar cred 805will be done. 806.It Ft kauth_cred_t Fn kauth_cred_get "void" 807Return the credentials associated with the current LWP. 808.El 809.Ss Scope Management 810.Nm 811provides routines to manage the creation and deletion of scopes on the 812system. 813.Pp 814Note that the built-in scopes, the 815.Dq generic 816scope and the 817.Dq process 818scope, can't be deleted. 819.Bl -tag 820.It Ft kauth_scope_t Fn kauth_register_scope "const char *id" \ 821"kauth_scope_callback_t cb" "void *cookie" 822Register a new scope on the system. 823.Ar id 824is the name of the scope, usually in reverse DNS-like notation. 825For example, 826.Dq org.netbsd.kauth.myscope . 827.Ar cb 828is the default listener, to which authorization requests for this scope 829will be dispatched to. 830.Ar cookie 831is optional user-data that will be passed to all listeners 832during authorization on the scope. 833.It Ft void Fn kauth_deregister_scope "kauth_scope_t scope" 834Deregister 835.Ar scope 836from the scopes available on the system. 837.El 838.Ss Listener Management 839Listeners in 840.Nm 841are authorization callbacks that are called during an authorization 842request in the scope which they belong to. 843.Pp 844When an authorization request is made, all listeners associated with 845a scope are called to allow, deny, or defer the request. 846.Pp 847It is enough for one listener to deny the request in order for the 848request to be denied; but all listeners are called during an authorization 849process none-the-less. 850All listeners are required to allow the request for it to be granted, 851and in a case where all listeners defer the request -- leaving the decision 852for other listeners -- the request is denied. 853.Pp 854The following KPI is provided for the management of listeners: 855.Bl -tag 856.It Ft kauth_listener_t Fn kauth_listen_scope "const char *id" \ 857"kauth_scope_callback_t cb" "void *cookie" 858Create a new listener on the scope with the id 859.Ar id , 860setting the default listener to 861.Ar cb . 862.\".Ar cookie 863.\"is optional user-data that will be passed to the listener when called 864.\"during an authorization request. 865.It Ft void Fn kauth_unlisten_scope "kauth_listener_t listener" 866Remove 867.Ar listener 868from the scope which it belongs to. 869.Pp 870Effectively what this does is is remove the callback from the chain of 871functions to be called when an authorization request is made, preventing 872from the listener from being entered in the future. 873.El 874.Pp 875.Nm 876provides no means for synchronization within listeners. 877It is the the programmer's responsibility to make sure data used by the 878listener is properly locked during its use, as it can be accessed 879simultaneously from the same listener called multiple times. 880It is also the programmer's responsibility to do garbage collection after 881the listener, possibly freeing any allocated data it used. 882.Pp 883The common method to do the above is by having a reference count to 884each listener. 885On entry to the listener, this reference count should be raised, and 886on exit -- lowered. 887.Pp 888During the removal of a listener, first 889.Fn kauth_scope_unlisten 890should be called to make sure the listener code will not be entered in 891the future. 892Then, the code should wait (possibly sleeping) until the reference count 893drops to zero. 894When that happens, it is safe to do the final cleanup. 895.Pp 896Listeners might sleep, so no locks can be held when calling an authorization 897wrapper. 898.\".Sh EXAMPLES 899.Sh SEE ALSO 900.Xr secmodel 9 901.Sh HISTORY 902The kernel authorization framework first appeared in Mac OS X 10.4. 903.Pp 904The kernel authorization framework in 905.Nx 906first appeared in 907.Nx 4.0 , 908and is a clean-room implementation based on Apple TN2127, available at 909http://developer.apple.com/technotes/tn2005/tn2127.html 910.Sh AUTHORS 911.An Elad Efrat Aq elad@NetBSD.org 912implemented the kernel authorization framework in 913.Nx . 914.Pp 915.An Jason R. Thorpe Aq thorpej@NetBSD.org 916provided guidance and answered questions about the Darwin implementation. 917.Sh ONE MORE THING 918The 919.Nm 920framework is dedicated to Brian Mitchell, one of the most talented people 921I know. 922Thanks for everything. 923