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1 .\" $NetBSD: puffs_cred.3,v 1.4 2009/02/20 14:26:56 pooka Exp $
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26 .Dd October 18, 2007
27 .Dt PUFFS_CRED 3
28 .Os
29 .Sh NAME
30 .Nm puffs_cred
31 .Nd puffs credential and access control routines
32 .Sh LIBRARY
33 .Lb libpuffs
34 .Sh SYNOPSIS
35 .In puffs.h
36 .Ft int
37 .Fn puffs_cred_getuid "const struct puffs_cred *pcr" "uid_t *uid"
38 .Ft int
39 .Fn puffs_cred_getgid "const struct puffs_cred *pcr" "gid_t *gid"
40 .Ft int
41 .Fo puffs_cred_getgroups
42 .Fa "const struct puffs_cred *pcr" "gid_t *gids" "short *ngids"
43 .Fc
44 .Pp
45 .Ft bool
46 .Fn puffs_cred_isuid "const struct puffs_cred *pcr" "uid_t uid"
47 .Ft bool
48 .Fn puffs_cred_hasgroup "const struct puffs_cred *pcr" "gid_t gid"
49 .Ft bool
50 .Fn puffs_cred_iskernel "const struct puffs_cred *pcr"
51 .Ft bool
52 .Fn puffs_cred_isfs "const struct puffs_cred *pcr"
53 .Ft bool
54 .Fn puffs_cred_isjuggernaut "const struct puffs_cred *pcr"
55 .Pp
56 .Ft int
57 .Fo puffs_access
58 .Fa "enum vtype type" "mode_t file_mode" "uid_t owner" "gid_t group"
59 .Fa "mode_t access_mode" "const struct puffs_cred *pcr"
60 .Fc
61 .Ft int
62 .Fo puffs_access_chown
63 .Fa "uid_t owner" "gid_t group" "uid_t newowner" "gid_t newgroup"
64 .Fa "const struct puffs_cred *pcr"
65 .Fc
66 .Ft int
67 .Fo puffs_access_chmod
68 .Fa "uid_t owner" "gid_t group" "enum vtype type" "mode_t newmode"
69 .Fa "const struct puffs_cred *pcr"
70 .Fc
71 .Ft int
72 .Fo puffs_access_times
73 .Fa "uid_t owner" "gid_t group" "mode_t file_mode" "int va_utimes_null"
74 .Fa "const struct puffs_cred *pcr"
75 .Fc
76 .Sh DESCRIPTION
77 These functions can be used to check operation credentials and perform
78 access control.
79 The structure
80 .Vt struct puffs_cred
81 can contain two types of credentials: ones belonging to users and
82 ones belonging to the kernel.
83 The latter is further divided into generic kernel credentials and
84 file system credentials.
85 The general rule is that these should be treated as more powerful
86 than superuser credentials, but the file system is free to treat
87 them as it sees fit.
88 .Ss Credentials
89 The
90 .Fn puffs_cred_get
91 family of functions fetch the uid or gid(s) from the given credential
92 cookie.
93 They return 0 for success or \-1 for an error and set
94 .Va errno .
95 An error happens when the credentials represent kernel or file system
96 credentials and do not contain an uid or gid(s).
97 .Pp
98 For
99 .Fn puffs_cred_getgroups ,
100 the argument
101 .Fa gids
102 should point to an array with room for
103 .Fa *ngids
104 elements.
105 .Pp
106 The
107 .Fn puffs_cred_is
108 family of functions return 1 if the truth value of the function for
109 .Fa pcr
110 is true and 0 if it is false.
111 The function
112 .Fn puffs_cred_isjuggernaut
113 is true if
114 .Fa pcr
115 describes superuser, kernel or file system credentials.
116 .Ss Access Control
117 To help the programmers task of emulating normal kernel file system
118 access control semantics, several helper functions are provided to
119 check if access is allowed.
120 They return 0 if access should be permitted or an errno value to
121 indicate that access should be denied with the returned value.
122 .Pp
123 .Fn puffs_access
124 is equivalent to the kernel
125 .Fn vaccess
126 function.
127 The arguments specify current information of the file to be
128 tested with the exception of
129 .Fa access_mode ,
130 which is a combination of
131 .Dv PUFFS_VREAD ,
132 .Dv PUFFS_VWRITE
133 and
134 .Dv PUFFS_VEXEC
135 indicating the desired file access mode.
136 .Pp
137 The rest of the functions provide UFS semantics for operations.
138 .Fn puffs_access_chown
139 checks if it is permissible to chown a file with the current uid
140 and gid to the new uid and gid with the credentials of
141 .Fa pcr .
142 .Pp
143 .Fn puffs_access_chmod
144 checks against permission to chmod a file of type
145 .Fa type
146 to the mode
147 .Fa newmode .
148 .Pp
149 Finally,
150 .Fn puffs_access_times
151 checks if it is allowable to update the timestamps of a file.
152 The argument
153 .Fa va_utimes_null
154 signals if the flags
155 .Dv VA_UTIMES_NULL
156 was set in
157 .Fa va_vaflags
158 of
159 .Va struct vattr .
160 If coming from a path where this information is unavailable, passing
161 0 as this argument restricts the permission of modification to the
162 owner and superuser.
163 Otherwise the function checks for write permissions to the node and
164 returns success if the caller has write permissions.
165 .Sh SEE ALSO
166 .Xr puffs 3 ,
167 .Xr vnode 9