1CAP_GET_PROC(3) Linux Programmer's Manual CAP_GET_PROC(3)
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6 cap_get_proc, cap_set_proc, capgetp - capability manipulation on pro‐
7 cesses
8
10 #include <sys/capability.h>
11 cap_t cap_get_proc(void);
13 int cap_set_proc(cap_t cap_p);
15 #include <sys/types.h>
17 cap_t cap_get_pid(pid_t pid);
19 Link with -lcap.
21
23 cap_get_proc() allocates a capability state in working storage, sets
24 its state to that of the calling process, and returns a pointer to this
25 newly created capability state. The caller should free any releasable
26 memory, when the capability state in working storage is no longer
27 required, by calling cap_free() with the cap_t as an argument.
28 cap_set_proc() sets the values for all capability flags for all capa‐
30 bilities to the capability state identified by cap_p. The new capabil‐
31 ity state of the process will be completely determined by the contents
32 of cap_p upon successful return from this function. If any flag in
33 cap_p is set for any capability not currently permitted for the calling
34 process, the function will fail, and the capability state of the
35 process will remain unchanged.
36 cap_get_pid() returns cap_d, see cap_init(3), with the process capabil‐
38 ities of the process indicated by pid. This information can also be
39 obtained from the /proc/<pid>/status file.
40
42 The functions cap_get_proc() and cap_get_pid() return a non-NULL value
43 on success, and NULL on failure.
44 The function cap_set_proc() return zero for success, and -1 on failure.
46 On failure, errno is set to EINVAL, EPERM, or ENOMEM.
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50 cap_set_proc() and cap_get_proc() are specified in the withdrawn
51 POSIX.1e draft specification. cap_get_pid() is a Linux extension.
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54 The library also supports the deprecated functions:
55 int capgetp(pid_t pid, cap_t cap_d);
57 int capsetp(pid_t pid, cap_t cap_d);
59 capgetp() attempts to obtain the capabilities of some other process;
61 storing the capabilities in a pre-allocated cap_d.See cap_init() for
62 information on allocating an empty capability set. This function,
63 capgetp(), is deprecated, you should use cap_get_pid().
64 capsetp() attempts to set the capabilities of some other process(es),
66 pid. If pid is positive it refers to a specific process; if it is
67 zero, it refers to the current process; -1 refers to all processes
68 other than the current process and process '1' (typically init(8));
69 other negative values refer to the -pid process group. In order to use
70 this function, the kernel must support it and the current process must
71 have CAP_SETPCAP raised in its Effective capability set. The capabili‐
72 ties set in the target process(es) are those contained in cap_d. Ker‐
73 nels that support filesystem capabilities redefine the semantics of
74 CAP_SETPCAP and on such systems this function will always fail for any
75 target not equal to the current process. capsetp() returns zero for
76 success, and -1 on failure.
77 Where supported by the kernel, the function capsetp() should be used
79 with care. It existed, primarily, to overcome an early lack of support
80 for capabilities in the filesystems supported by Linux. Note that, by
81 default, the only processes that have CAP_SETPCAP available to them are
82 processes started as a kernel thread. (Typically this includes
83 init(8), kflushd and kswapd). You will need to recompile the kernel to
84 modify this default.
85
87 The code segment below raises the CAP_FOWNER and CAP_SETFCAP effective
88 capabilities for the caller:
89 cap_t caps;
91 cap_value_t cap_list[2];
92 caps = cap_get_proc();
94 if (caps == NULL)
95 /* handle error */;
96 cap_list[0] = CAP_FOWNER;
98 cap_list[1] = CAP_SETFCAP;
99 if (cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_list, CAP_SET) == -1)
100 /* handle error */;
101 if (cap_set_proc(caps) == -1)
103 /* handle error */;
104 if (cap_free(caps) == -1)
106 /* handle error */;
107
109 libcap(3), cap_clear(3), cap_copy_ext(3), cap_from_text(3),
110 cap_get_file(3), cap_init(3), capabilities(7)
111 2008-05-11 CAP_GET_PROC(3)