1 /* 2 * linux/kernel/capability.c 3 * 4 * Copyright (C) 1997 Andrew Main <zefram@fysh.org> 5 * 6 * Integrated into 2.1.97+, Andrew G. Morgan <morgan@transmeta.com> 7 * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net> 8 */ 9 10 #include <linux/capability.h> 11 #include <linux/mm.h> 12 #include <linux/module.h> 13 #include <linux/security.h> 14 #include <linux/syscalls.h> 15 #include <asm/uaccess.h> 16 17 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */ 18 kernel_cap_t cap_bset = CAP_INIT_EFF_SET; 19 20 EXPORT_SYMBOL(securebits); 21 EXPORT_SYMBOL(cap_bset); 22 23 /* 24 * This lock protects task->cap_* for all tasks including current. 25 * Locking rule: acquire this prior to tasklist_lock. 26 */ 27 static DEFINE_SPINLOCK(task_capability_lock); 28 29 /* 30 * For sys_getproccap() and sys_setproccap(), any of the three 31 * capability set pointers may be NULL -- indicating that that set is 32 * uninteresting and/or not to be changed. 33 */ 34 35 /** 36 * sys_capget - get the capabilities of a given process. 37 * @header: pointer to struct that contains capability version and 38 * target pid data 39 * @dataptr: pointer to struct that contains the effective, permitted, 40 * and inheritable capabilities that are returned 41 * 42 * Returns 0 on success and < 0 on error. 43 */ 44 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr) 45 { 46 int ret = 0; 47 pid_t pid; 48 __u32 version; 49 struct task_struct *target; 50 struct __user_cap_data_struct data; 51 52 if (get_user(version, &header->version)) 53 return -EFAULT; 54 55 if (version != _LINUX_CAPABILITY_VERSION) { 56 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) 57 return -EFAULT; 58 return -EINVAL; 59 } 60 61 if (get_user(pid, &header->pid)) 62 return -EFAULT; 63 64 if (pid < 0) 65 return -EINVAL; 66 67 spin_lock(&task_capability_lock); 68 read_lock(&tasklist_lock); 69 70 if (pid && pid != current->pid) { 71 target = find_task_by_pid(pid); 72 if (!target) { 73 ret = -ESRCH; 74 goto out; 75 } 76 } else 77 target = current; 78 79 ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted); 80 81 out: 82 read_unlock(&tasklist_lock); 83 spin_unlock(&task_capability_lock); 84 85 if (!ret && copy_to_user(dataptr, &data, sizeof data)) 86 return -EFAULT; 87 88 return ret; 89 } 90 91 /* 92 * cap_set_pg - set capabilities for all processes in a given process 93 * group. We call this holding task_capability_lock and tasklist_lock. 94 */ 95 static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective, 96 kernel_cap_t *inheritable, 97 kernel_cap_t *permitted) 98 { 99 struct task_struct *g, *target; 100 int ret = -EPERM; 101 int found = 0; 102 struct pid *pgrp; 103 104 pgrp = find_pid(pgrp_nr); 105 do_each_pid_task(pgrp, PIDTYPE_PGID, g) { 106 target = g; 107 while_each_thread(g, target) { 108 if (!security_capset_check(target, effective, 109 inheritable, 110 permitted)) { 111 security_capset_set(target, effective, 112 inheritable, 113 permitted); 114 ret = 0; 115 } 116 found = 1; 117 } 118 } while_each_pid_task(pgrp, PIDTYPE_PGID, g); 119 120 if (!found) 121 ret = 0; 122 return ret; 123 } 124 125 /* 126 * cap_set_all - set capabilities for all processes other than init 127 * and self. We call this holding task_capability_lock and tasklist_lock. 128 */ 129 static inline int cap_set_all(kernel_cap_t *effective, 130 kernel_cap_t *inheritable, 131 kernel_cap_t *permitted) 132 { 133 struct task_struct *g, *target; 134 int ret = -EPERM; 135 int found = 0; 136 137 do_each_thread(g, target) { 138 if (target == current || is_init(target)) 139 continue; 140 found = 1; 141 if (security_capset_check(target, effective, inheritable, 142 permitted)) 143 continue; 144 ret = 0; 145 security_capset_set(target, effective, inheritable, permitted); 146 } while_each_thread(g, target); 147 148 if (!found) 149 ret = 0; 150 return ret; 151 } 152 153 /** 154 * sys_capset - set capabilities for a process or a group of processes 155 * @header: pointer to struct that contains capability version and 156 * target pid data 157 * @data: pointer to struct that contains the effective, permitted, 158 * and inheritable capabilities 159 * 160 * Set capabilities for a given process, all processes, or all 161 * processes in a given process group. 162 * 163 * The restrictions on setting capabilities are specified as: 164 * 165 * [pid is for the 'target' task. 'current' is the calling task.] 166 * 167 * I: any raised capabilities must be a subset of the (old current) permitted 168 * P: any raised capabilities must be a subset of the (old current) permitted 169 * E: must be set to a subset of (new target) permitted 170 * 171 * Returns 0 on success and < 0 on error. 172 */ 173 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data) 174 { 175 kernel_cap_t inheritable, permitted, effective; 176 __u32 version; 177 struct task_struct *target; 178 int ret; 179 pid_t pid; 180 181 if (get_user(version, &header->version)) 182 return -EFAULT; 183 184 if (version != _LINUX_CAPABILITY_VERSION) { 185 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) 186 return -EFAULT; 187 return -EINVAL; 188 } 189 190 if (get_user(pid, &header->pid)) 191 return -EFAULT; 192 193 if (pid && pid != current->pid && !capable(CAP_SETPCAP)) 194 return -EPERM; 195 196 if (copy_from_user(&effective, &data->effective, sizeof(effective)) || 197 copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) || 198 copy_from_user(&permitted, &data->permitted, sizeof(permitted))) 199 return -EFAULT; 200 201 spin_lock(&task_capability_lock); 202 read_lock(&tasklist_lock); 203 204 if (pid > 0 && pid != current->pid) { 205 target = find_task_by_pid(pid); 206 if (!target) { 207 ret = -ESRCH; 208 goto out; 209 } 210 } else 211 target = current; 212 213 ret = 0; 214 215 /* having verified that the proposed changes are legal, 216 we now put them into effect. */ 217 if (pid < 0) { 218 if (pid == -1) /* all procs other than current and init */ 219 ret = cap_set_all(&effective, &inheritable, &permitted); 220 221 else /* all procs in process group */ 222 ret = cap_set_pg(-pid, &effective, &inheritable, 223 &permitted); 224 } else { 225 ret = security_capset_check(target, &effective, &inheritable, 226 &permitted); 227 if (!ret) 228 security_capset_set(target, &effective, &inheritable, 229 &permitted); 230 } 231 232 out: 233 read_unlock(&tasklist_lock); 234 spin_unlock(&task_capability_lock); 235 236 return ret; 237 } 238 239 int __capable(struct task_struct *t, int cap) 240 { 241 if (security_capable(t, cap) == 0) { 242 t->flags |= PF_SUPERPRIV; 243 return 1; 244 } 245 return 0; 246 } 247 EXPORT_SYMBOL(__capable); 248 249 int capable(int cap) 250 { 251 return __capable(current, cap); 252 } 253 EXPORT_SYMBOL(capable); 254