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32 .Nd "library for getting or setting system information in capability mode"
37 .In casper/cap_sysctl.h
39 .Fn cap_sysctl "cap_channel_t *chan" "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen"
41 .Fn cap_sysctlbyname "cap_channel_t *chan" "const char *name" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen"
43 .Fn cap_sysctlnametomib "cap_channel_t *chan" "const char *name" "int *mibp" "size_t *sizep"
44 .Ft cap_sysctl_limit_t *
45 .Fn cap_sysctl_limit_init "cap_channel_t *chan"
46 .Ft cap_sysctl_limit_t *
47 .Fn cap_sysctl_limit_name "cap_sysctl_limit_t *limit" "const char *name" "int flags"
48 .Ft cap_sysctl_limit_t *
49 .Fn cap_sysctl_limit_mib "cap_sysctl_limit_t *limit" "const int *mibp" "u_int miblen" "int flags"
51 .Fn cap_sysctl_limit "cap_sysctl_limit_t *limit"
57 .Fn cap_sysctlnametomib
58 functions are equivalent to
62 .Xr sysctlnametomib 3 ,
63 except that they are implemented by the
66 service and require a corresponding
72 capability provides unrestricted access to the sysctl namespace.
73 Applications typically only require access to a small number of sysctl
76 interface can be used to restrict the sysctls that can be accessed using
80 .Fn cap_sysctl_limit_init
81 returns an opaque limit handle used to store a list of permitted sysctls
83 Rights are encoded using the following flags:
85 .Bd -literal -offset indent -compact
86 CAP_SYSCTL_READ allow reads of the sysctl variable
87 CAP_SYSCTL_WRITE allow writes of the sysctl variable
88 CAP_SYSCTL_RDWR allow reads and writes of the sysctl variable
89 CAP_RECURSIVE permit access to any child of the sysctl variable
93 .Fn cap_sysctl_limit_name
94 function adds the sysctl identified by
96 to the limit list, and
97 .Fn cap_sysctl_limit_mib
98 function adds the sysctl identified by
101 The access rights for the sysctl are specified in the
103 parameter; at least one of
104 .Dv CAP_SYSCTL_READ ,
110 applies a set of sysctl limits to the capability, denying access to sysctl
111 variables not belonging to the set.
112 It consumes the limit handle.
113 After either success or failure, the user must not access the handle again.
115 Once a set of limits is applied, subsequent calls to
117 will fail unless the new set is a subset of the current set.
119 .Fn cap_sysctlnametomib
120 will succeed so long as the named sysctl variable is present in the limit set,
121 regardless of its access rights.
122 When a sysctl variable name is added to a limit set, its MIB identifier is
123 automatically added to the set.
125 The following example first opens a capability to casper, uses this
126 capability to create the
128 casper service, and then uses the
130 capability to get the value of
131 .Dv kern.trap_enotcap .
133 cap_channel_t *capcas, *capsysctl;
134 const char *name = "kern.trap_enotcap";
139 /* Open capability to Casper. */
142 err(1, "Unable to contact Casper");
144 /* Enter capability mode sandbox. */
145 if (cap_enter() < 0 && errno != ENOSYS)
146 err(1, "Unable to enter capability mode");
148 /* Use Casper capability to create capability to the system.sysctl service. */
149 capsysctl = cap_service_open(capcas, "system.sysctl");
150 if (capsysctl == NULL)
151 err(1, "Unable to open system.sysctl service");
153 /* Close Casper capability, we don't need it anymore. */
156 /* Create limit for one MIB with read access only. */
157 limit = cap_sysctl_limit_init(capsysctl);
158 (void)cap_sysctl_limit_name(limit, name, CAP_SYSCTL_READ);
160 /* Limit system.sysctl. */
161 if (cap_sysctl_limit(limit) < 0)
162 err(1, "Unable to set limits");
165 size = sizeof(value);
166 if (cap_sysctlbyname(capsysctl, name, &value, &size, NULL, 0) < 0)
167 err(1, "Unable to get value of sysctl");
169 printf("The value of %s is %d.\\n", name, value);
171 cap_close(capsysctl);
174 .Fn cap_sysctl_limit_init
175 will return a new limit handle on success or
179 .Fn cap_sysctl_limit_mib
181 .Fn cap_sysctl_limit_name
182 will return the modified limit handle on success or
186 After failure, the caller must not access the limit handle again.
193 .Fn cap_sysctlbyname ,
195 .Fn cap_sysctlnametomib
196 have the same return values as their non-capability-mode equivalents as
204 .Xr sysctlnametomib 3 ,
210 service first appeared in
215 service was implemented by
216 .An Pawel Jakub Dawidek Aq Mt pawel@dawidek.net
217 under sponsorship from the FreeBSD Foundation.
219 This manual page was written by
220 .An Mariusz Zaborski Aq Mt oshogbo@FreeBSD.org .