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TOMOYO Linux Cross Reference
Linux/kernel/exec_domain.c

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  1 /*
  2  * Handling of different ABIs (personalities).
  3  *
  4  * We group personalities into execution domains which have their
  5  * own handlers for kernel entry points, signal mapping, etc...
  6  *
  7  * 2001-05-06   Complete rewrite,  Christoph Hellwig (hch@infradead.org)
  8  */
  9 
 10 #include <linux/init.h>
 11 #include <linux/kernel.h>
 12 #include <linux/kmod.h>
 13 #include <linux/module.h>
 14 #include <linux/personality.h>
 15 #include <linux/proc_fs.h>
 16 #include <linux/sched.h>
 17 #include <linux/seq_file.h>
 18 #include <linux/syscalls.h>
 19 #include <linux/sysctl.h>
 20 #include <linux/types.h>
 21 #include <linux/fs_struct.h>
 22 
 23 
 24 static void default_handler(int, struct pt_regs *);
 25 
 26 static struct exec_domain *exec_domains = &default_exec_domain;
 27 static DEFINE_RWLOCK(exec_domains_lock);
 28 
 29 
 30 static unsigned long ident_map[32] = {
 31         0,      1,      2,      3,      4,      5,      6,      7,
 32         8,      9,      10,     11,     12,     13,     14,     15,
 33         16,     17,     18,     19,     20,     21,     22,     23,
 34         24,     25,     26,     27,     28,     29,     30,     31
 35 };
 36 
 37 struct exec_domain default_exec_domain = {
 38         .name           = "Linux",              /* name */
 39         .handler        = default_handler,      /* lcall7 causes a seg fault. */
 40         .pers_low       = 0,                    /* PER_LINUX personality. */
 41         .pers_high      = 0,                    /* PER_LINUX personality. */
 42         .signal_map     = ident_map,            /* Identity map signals. */
 43         .signal_invmap  = ident_map,            /*  - both ways. */
 44 };
 45 
 46 
 47 static void
 48 default_handler(int segment, struct pt_regs *regp)
 49 {
 50         set_personality(0);
 51 
 52         if (current_thread_info()->exec_domain->handler != default_handler)
 53                 current_thread_info()->exec_domain->handler(segment, regp);
 54         else
 55                 send_sig(SIGSEGV, current, 1);
 56 }
 57 
 58 static struct exec_domain *
 59 lookup_exec_domain(unsigned int personality)
 60 {
 61         unsigned int pers = personality(personality);
 62         struct exec_domain *ep;
 63 
 64         read_lock(&exec_domains_lock);
 65         for (ep = exec_domains; ep; ep = ep->next) {
 66                 if (pers >= ep->pers_low && pers <= ep->pers_high)
 67                         if (try_module_get(ep->module))
 68                                 goto out;
 69         }
 70 
 71 #ifdef CONFIG_MODULES
 72         read_unlock(&exec_domains_lock);
 73         request_module("personality-%d", pers);
 74         read_lock(&exec_domains_lock);
 75 
 76         for (ep = exec_domains; ep; ep = ep->next) {
 77                 if (pers >= ep->pers_low && pers <= ep->pers_high)
 78                         if (try_module_get(ep->module))
 79                                 goto out;
 80         }
 81 #endif
 82 
 83         ep = &default_exec_domain;
 84 out:
 85         read_unlock(&exec_domains_lock);
 86         return (ep);
 87 }
 88 
 89 int
 90 register_exec_domain(struct exec_domain *ep)
 91 {
 92         struct exec_domain      *tmp;
 93         int                     err = -EBUSY;
 94 
 95         if (ep == NULL)
 96                 return -EINVAL;
 97 
 98         if (ep->next != NULL)
 99                 return -EBUSY;
100 
101         write_lock(&exec_domains_lock);
102         for (tmp = exec_domains; tmp; tmp = tmp->next) {
103                 if (tmp == ep)
104                         goto out;
105         }
106 
107         ep->next = exec_domains;
108         exec_domains = ep;
109         err = 0;
110 
111 out:
112         write_unlock(&exec_domains_lock);
113         return (err);
114 }
115 
116 int
117 unregister_exec_domain(struct exec_domain *ep)
118 {
119         struct exec_domain      **epp;
120 
121         epp = &exec_domains;
122         write_lock(&exec_domains_lock);
123         for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
124                 if (ep == *epp)
125                         goto unregister;
126         }
127         write_unlock(&exec_domains_lock);
128         return -EINVAL;
129 
130 unregister:
131         *epp = ep->next;
132         ep->next = NULL;
133         write_unlock(&exec_domains_lock);
134         return 0;
135 }
136 
137 int __set_personality(unsigned int personality)
138 {
139         struct exec_domain *oep = current_thread_info()->exec_domain;
140 
141         current_thread_info()->exec_domain = lookup_exec_domain(personality);
142         current->personality = personality;
143         module_put(oep->module);
144 
145         return 0;
146 }
147 
148 #ifdef CONFIG_PROC_FS
149 static int execdomains_proc_show(struct seq_file *m, void *v)
150 {
151         struct exec_domain      *ep;
152 
153         read_lock(&exec_domains_lock);
154         for (ep = exec_domains; ep; ep = ep->next)
155                 seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
156                                ep->pers_low, ep->pers_high, ep->name,
157                                module_name(ep->module));
158         read_unlock(&exec_domains_lock);
159         return 0;
160 }
161 
162 static int execdomains_proc_open(struct inode *inode, struct file *file)
163 {
164         return single_open(file, execdomains_proc_show, NULL);
165 }
166 
167 static const struct file_operations execdomains_proc_fops = {
168         .open           = execdomains_proc_open,
169         .read           = seq_read,
170         .llseek         = seq_lseek,
171         .release        = single_release,
172 };
173 
174 static int __init proc_execdomains_init(void)
175 {
176         proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
177         return 0;
178 }
179 module_init(proc_execdomains_init);
180 #endif
181 
182 SYSCALL_DEFINE1(personality, unsigned int, personality)
183 {
184         unsigned int old = current->personality;
185 
186         if (personality != 0xffffffff)
187                 set_personality(personality);
188 
189         return old;
190 }
191 
192 
193 EXPORT_SYMBOL(register_exec_domain);
194 EXPORT_SYMBOL(unregister_exec_domain);
195 EXPORT_SYMBOL(__set_personality);
196 

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