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-rw-r--r--kernel/capability.c111
1 files changed, 73 insertions, 38 deletions
diff --git a/kernel/capability.c b/kernel/capability.c
index 39e8193b41ea..cfbe44299488 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -53,6 +53,69 @@ static void warn_legacy_capability_use(void)
53} 53}
54 54
55/* 55/*
56 * Version 2 capabilities worked fine, but the linux/capability.h file
57 * that accompanied their introduction encouraged their use without
58 * the necessary user-space source code changes. As such, we have
59 * created a version 3 with equivalent functionality to version 2, but
60 * with a header change to protect legacy source code from using
61 * version 2 when it wanted to use version 1. If your system has code
62 * that trips the following warning, it is using version 2 specific
63 * capabilities and may be doing so insecurely.
64 *
65 * The remedy is to either upgrade your version of libcap (to 2.10+,
66 * if the application is linked against it), or recompile your
67 * application with modern kernel headers and this warning will go
68 * away.
69 */
70
71static void warn_deprecated_v2(void)
72{
73 static int warned;
74
75 if (!warned) {
76 char name[sizeof(current->comm)];
77
78 printk(KERN_INFO "warning: `%s' uses deprecated v2"
79 " capabilities in a way that may be insecure.\n",
80 get_task_comm(name, current));
81 warned = 1;
82 }
83}
84
85/*
86 * Version check. Return the number of u32s in each capability flag
87 * array, or a negative value on error.
88 */
89static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
90{
91 __u32 version;
92
93 if (get_user(version, &header->version))
94 return -EFAULT;
95
96 switch (version) {
97 case _LINUX_CAPABILITY_VERSION_1:
98 warn_legacy_capability_use();
99 *tocopy = _LINUX_CAPABILITY_U32S_1;
100 break;
101 case _LINUX_CAPABILITY_VERSION_2:
102 warn_deprecated_v2();
103 /*
104 * fall through - v3 is otherwise equivalent to v2.
105 */
106 case _LINUX_CAPABILITY_VERSION_3:
107 *tocopy = _LINUX_CAPABILITY_U32S_3;
108 break;
109 default:
110 if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
111 return -EFAULT;
112 return -EINVAL;
113 }
114
115 return 0;
116}
117
118/*
56 * For sys_getproccap() and sys_setproccap(), any of the three 119 * For sys_getproccap() and sys_setproccap(), any of the three
57 * capability set pointers may be NULL -- indicating that that set is 120 * capability set pointers may be NULL -- indicating that that set is
58 * uninteresting and/or not to be changed. 121 * uninteresting and/or not to be changed.
@@ -71,27 +134,13 @@ asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
71{ 134{
72 int ret = 0; 135 int ret = 0;
73 pid_t pid; 136 pid_t pid;
74 __u32 version;
75 struct task_struct *target; 137 struct task_struct *target;
76 unsigned tocopy; 138 unsigned tocopy;
77 kernel_cap_t pE, pI, pP; 139 kernel_cap_t pE, pI, pP;
78 140
79 if (get_user(version, &header->version)) 141 ret = cap_validate_magic(header, &tocopy);
80 return -EFAULT; 142 if (ret != 0)
81 143 return ret;
82 switch (version) {
83 case _LINUX_CAPABILITY_VERSION_1:
84 warn_legacy_capability_use();
85 tocopy = _LINUX_CAPABILITY_U32S_1;
86 break;
87 case _LINUX_CAPABILITY_VERSION_2:
88 tocopy = _LINUX_CAPABILITY_U32S_2;
89 break;
90 default:
91 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
92 return -EFAULT;
93 return -EINVAL;
94 }
95 144
96 if (get_user(pid, &header->pid)) 145 if (get_user(pid, &header->pid))
97 return -EFAULT; 146 return -EFAULT;
@@ -118,7 +167,7 @@ out:
118 spin_unlock(&task_capability_lock); 167 spin_unlock(&task_capability_lock);
119 168
120 if (!ret) { 169 if (!ret) {
121 struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S]; 170 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
122 unsigned i; 171 unsigned i;
123 172
124 for (i = 0; i < tocopy; i++) { 173 for (i = 0; i < tocopy; i++) {
@@ -128,7 +177,7 @@ out:
128 } 177 }
129 178
130 /* 179 /*
131 * Note, in the case, tocopy < _LINUX_CAPABILITY_U32S, 180 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
132 * we silently drop the upper capabilities here. This 181 * we silently drop the upper capabilities here. This
133 * has the effect of making older libcap 182 * has the effect of making older libcap
134 * implementations implicitly drop upper capability 183 * implementations implicitly drop upper capability
@@ -240,30 +289,16 @@ static inline int cap_set_all(kernel_cap_t *effective,
240 */ 289 */
241asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data) 290asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
242{ 291{
243 struct __user_cap_data_struct kdata[_LINUX_CAPABILITY_U32S]; 292 struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
244 unsigned i, tocopy; 293 unsigned i, tocopy;
245 kernel_cap_t inheritable, permitted, effective; 294 kernel_cap_t inheritable, permitted, effective;
246 __u32 version;
247 struct task_struct *target; 295 struct task_struct *target;
248 int ret; 296 int ret;
249 pid_t pid; 297 pid_t pid;
250 298
251 if (get_user(version, &header->version)) 299 ret = cap_validate_magic(header, &tocopy);
252 return -EFAULT; 300 if (ret != 0)
253 301 return ret;
254 switch (version) {
255 case _LINUX_CAPABILITY_VERSION_1:
256 warn_legacy_capability_use();
257 tocopy = _LINUX_CAPABILITY_U32S_1;
258 break;
259 case _LINUX_CAPABILITY_VERSION_2:
260 tocopy = _LINUX_CAPABILITY_U32S_2;
261 break;
262 default:
263 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
264 return -EFAULT;
265 return -EINVAL;
266 }
267 302
268 if (get_user(pid, &header->pid)) 303 if (get_user(pid, &header->pid))
269 return -EFAULT; 304 return -EFAULT;
@@ -281,7 +316,7 @@ asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
281 permitted.cap[i] = kdata[i].permitted; 316 permitted.cap[i] = kdata[i].permitted;
282 inheritable.cap[i] = kdata[i].inheritable; 317 inheritable.cap[i] = kdata[i].inheritable;
283 } 318 }
284 while (i < _LINUX_CAPABILITY_U32S) { 319 while (i < _KERNEL_CAPABILITY_U32S) {
285 effective.cap[i] = 0; 320 effective.cap[i] = 0;
286 permitted.cap[i] = 0; 321 permitted.cap[i] = 0;
287 inheritable.cap[i] = 0; 322 inheritable.cap[i] = 0;