source: branches/minix3-book/kernel/system/do_privctl.c

Last change on this file was 4, checked in by Mattia Monga, 14 years ago

Importazione sorgenti libro

File size: 2.9 KB
Line 
1/* The kernel call implemented in this file:
2 * m_type: SYS_PRIVCTL
3 *
4 * The parameters for this kernel call are:
5 * m1_i1: PR_PROC_NR (process number of caller)
6 */
7
8#include "../system.h"
9#include "../ipc.h"
10#include <signal.h>
11
12#if USE_PRIVCTL
13
14#define FILLED_MASK (~0)
15
16/*===========================================================================*
17 * do_privctl *
18 *===========================================================================*/
19PUBLIC int do_privctl(m_ptr)
20message *m_ptr; /* pointer to request message */
21{
22/* Handle sys_privctl(). Update a process' privileges. If the process is not
23 * yet a system process, make sure it gets its own privilege structure.
24 */
25 register struct proc *caller_ptr;
26 register struct proc *rp;
27 register struct priv *sp;
28 int proc_nr;
29 int priv_id;
30 int old_flags;
31 int i;
32
33 /* Check whether caller is allowed to make this call. Privileged proceses
34 * can only update the privileges of processes that are inhibited from
35 * running by the NO_PRIV flag. This flag is set when a privileged process
36 * forks.
37 */
38 caller_ptr = proc_addr(m_ptr->m_source);
39 if (! (priv(caller_ptr)->s_flags & SYS_PROC)) return(EPERM);
40 proc_nr = m_ptr->PR_PROC_NR;
41 if (! isokprocn(proc_nr)) return(EINVAL);
42 rp = proc_addr(proc_nr);
43 if (! (rp->p_rts_flags & NO_PRIV)) return(EPERM);
44
45 /* Make sure this process has its own privileges structure. This may fail,
46 * since there are only a limited number of system processes. Then copy the
47 * privileges from the caller and restore some defaults.
48 */
49 if ((i=get_priv(rp, SYS_PROC)) != OK) return(i);
50 priv_id = priv(rp)->s_id; /* backup privilege id */
51 *priv(rp) = *priv(caller_ptr); /* copy from caller */
52 priv(rp)->s_id = priv_id; /* restore privilege id */
53 priv(rp)->s_proc_nr = proc_nr; /* reassociate process nr */
54
55 for (i=0; i< BITMAP_CHUNKS(NR_SYS_PROCS); i++) /* remove pending: */
56 priv(rp)->s_notify_pending.chunk[i] = 0; /* - notifications */
57 priv(rp)->s_int_pending = 0; /* - interrupts */
58 sigemptyset(&priv(rp)->s_sig_pending); /* - signals */
59
60 /* Now update the process' privileges as requested. */
61 rp->p_priv->s_trap_mask = FILLED_MASK;
62 for (i=0; i<BITMAP_CHUNKS(NR_SYS_PROCS); i++) {
63 rp->p_priv->s_ipc_to.chunk[i] = FILLED_MASK;
64 }
65 unset_sys_bit(rp->p_priv->s_ipc_to, USER_PRIV_ID);
66
67 /* All process that this process can send to must be able to reply.
68 * Therefore, their send masks should be updated as well.
69 */
70 for (i=0; i<NR_SYS_PROCS; i++) {
71 if (get_sys_bit(rp->p_priv->s_ipc_to, i)) {
72 set_sys_bit(priv_addr(i)->s_ipc_to, priv_id(rp));
73 }
74 }
75
76 /* Done. Privileges have been set. Allow process to run again. */
77 old_flags = rp->p_rts_flags; /* save value of the flags */
78 rp->p_rts_flags &= ~NO_PRIV;
79 if (old_flags != 0 && rp->p_rts_flags == 0) lock_enqueue(rp);
80 return(OK);
81}
82
83#endif /* USE_PRIVCTL */
84
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