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procfs: retrieve both RS tables from RS at once

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Previously, procfs would retrieve the rproc and rprocpub tables from
RS in two separate calls.  This allowed for a race condition where the
tables could change in between the calls, resulting in a panic in
procfs under certain circumstances.  RS now implements a new method
for getsysinfo that allows the retrieval of both tables at once.

Change-Id: I5ec22d25898361270c90e805a43fc6d76ad9e29d
This commit is contained in:
David van Moolenbroek 2014-12-19 13:40:10 +00:00
parent da21d85025
commit 0eabb93c0c
3 changed files with 39 additions and 18 deletions
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35
minix/fs/procfs/service.c
View File

@ -19,8 +19,11 @@ struct policies {
enum policy supported;
};
static struct rprocpub rprocpub[NR_SYS_PROCS];
static struct rproc rproc[NR_SYS_PROCS];
static struct {
struct rproc proc[NR_SYS_PROCS];
struct rprocpub pub[NR_SYS_PROCS];
} rproc;
static struct policies policies[NR_SYS_PROCS];
static struct inode *service_node;
@ -132,9 +135,9 @@ service_get_policies(struct policies * pol, index_t slot)
};
/* Find the related policy, based on the file name of the service. */
ref_label = strrchr(rprocpub[slot].proc_name, '/');
ref_label = strrchr(rproc.pub[slot].proc_name, '/');
if (NULL == ref_label)
ref_label = rprocpub[slot].proc_name;
ref_label = rproc.pub[slot].proc_name;
memset(pol[slot].formatted, 0, MAX_POL_FORMAT_SZ);
for(pos = 0; pos < (sizeof(def_pol) / sizeof(def_pol[0])); pos++) {
@ -161,11 +164,15 @@ service_update(void)
struct inode *node;
struct inode_stat stat;
index_t slot;
static int warned = FALSE;
int r;
/* There is not much we can do if either of these calls fails. */
(void)getsysinfo(RS_PROC_NR, SI_PROCPUB_TAB, rprocpub,
sizeof(rprocpub));
(void)getsysinfo(RS_PROC_NR, SI_PROC_TAB, rproc, sizeof(rproc));
/* There is not much we can do if this call fails. */
r = getsysinfo(RS_PROC_NR, SI_PROCALL_TAB, &rproc, sizeof(rproc));
if (r != OK && !warned) {
printf("PROCFS: unable to obtain RS tables (%d)\n", r);
warned = TRUE;
}
/*
* As with PIDs, we make two passes. Delete first, then add. This
@ -180,8 +187,8 @@ service_update(void)
* If the slot is no longer in use, or the label name does not
* match, the node must be deleted.
*/
if (!(rproc[slot].r_flags & RS_IN_USE) ||
strcmp(get_inode_name(node), rprocpub[slot].label))
if (!(rproc.proc[slot].r_flags & RS_IN_USE) ||
strcmp(get_inode_name(node), rproc.pub[slot].label))
delete_inode(node);
}
@ -191,11 +198,11 @@ service_update(void)
stat.gid = SUPER_USER;
for (slot = 0; slot < NR_SYS_PROCS; slot++) {
if (!(rproc[slot].r_flags & RS_IN_USE) ||
if (!(rproc.proc[slot].r_flags & RS_IN_USE) ||
get_inode_by_index(service_node, slot) != NULL)
continue;
node = add_inode(service_node, rprocpub[slot].label, slot,
node = add_inode(service_node, rproc.pub[slot].label, slot,
&stat, (index_t)0, (cbdata_t)slot);
if (node == NULL)
@ -277,8 +284,8 @@ service_read(struct inode * node)
return;
slot = get_inode_index(node);
rpub = &rprocpub[slot];
rp = &rproc[slot];
rpub = &rproc.pub[slot];
rp = &rproc.proc[slot];
/* TODO: add a large number of other fields! */
buf_printf("filename: %s\n", rpub->proc_name);

1
minix/include/minix/sysinfo.h
View File

@ -13,6 +13,7 @@ int getsysinfo(endpoint_t who, int what, void *where, size_t size);
#define SI_DATA_STORE 5 /* get copy of data store mappings */
#define SI_CALL_STATS 9 /* system call statistics */
#define SI_PROCPUB_TAB 11 /* copy of public entries of process table */
#define SI_PROCALL_TAB 12 /* copy of both private and public entries */
#endif

21
minix/servers/rs/request.c
View File

@ -867,18 +867,33 @@ message *m_ptr;
{
vir_bytes src_addr, dst_addr;
int dst_proc;
size_t len;
size_t size, len;
int s;
/* Check if the call can be allowed. */
if((s = check_call_permission(m_ptr->m_source, 0, NULL)) != OK)
return s;
dst_proc = m_ptr->m_source;
dst_addr = m_ptr->m_lsys_getsysinfo.where;
size = m_ptr->m_lsys_getsysinfo.size;
switch(m_ptr->m_lsys_getsysinfo.what) {
case SI_PROC_TAB:
src_addr = (vir_bytes) rproc;
len = sizeof(struct rproc) * NR_SYS_PROCS;
break;
case SI_PROCALL_TAB:
/* Copy out both tables, one after the other. */
src_addr = (vir_bytes) rproc;
len = sizeof(struct rproc) * NR_SYS_PROCS;
if (len > size)
return EINVAL;
if ((s = sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len)) != OK)
return s;
dst_addr += len;
size -= len;
/* FALLTHROUGH */
case SI_PROCPUB_TAB:
src_addr = (vir_bytes) rprocpub;
len = sizeof(struct rprocpub) * NR_SYS_PROCS;
@ -887,11 +902,9 @@ message *m_ptr;
return(EINVAL);
}
if (len != m_ptr->m_lsys_getsysinfo.size)
if (len != size)
return(EINVAL);
dst_proc = m_ptr->m_source;
dst_addr = m_ptr->m_lsys_getsysinfo.where;
return sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len);
}