1 #include <linux/sched.h> 2 #include <linux/errno.h> 3 #include <linux/dcache.h> 4 #include <linux/path.h> 5 #include <linux/fdtable.h> 6 #include <linux/namei.h> 7 #include <linux/pid.h> 8 #include <linux/security.h> 9 #include <linux/file.h> 10 #include <linux/seq_file.h> 11 12 #include <linux/proc_fs.h> 13 14 #include "internal.h" 15 #include "fd.h" 16 17 static int seq_show(struct seq_file *m, void *v) 18 { 19 struct files_struct *files = NULL; 20 int f_flags = 0, ret = -ENOENT; 21 struct file *file = NULL; 22 struct task_struct *task; 23 24 task = get_proc_task(m->private); 25 if (!task) 26 return -ENOENT; 27 28 files = get_files_struct(task); 29 put_task_struct(task); 30 31 if (files) { 32 int fd = proc_fd(m->private); 33 34 spin_lock(&files->file_lock); 35 file = fcheck_files(files, fd); 36 if (file) { 37 struct fdtable *fdt = files_fdtable(files); 38 39 f_flags = file->f_flags; 40 if (close_on_exec(fd, fdt)) 41 f_flags |= O_CLOEXEC; 42 43 get_file(file); 44 ret = 0; 45 } 46 spin_unlock(&files->file_lock); 47 put_files_struct(files); 48 } 49 50 if (!ret) { 51 seq_printf(m, "pos:\t%lli\nflags:\t0%o\n", 52 (long long)file->f_pos, f_flags); 53 if (file->f_op->show_fdinfo) 54 ret = file->f_op->show_fdinfo(m, file); 55 fput(file); 56 } 57 58 return ret; 59 } 60 61 static int seq_fdinfo_open(struct inode *inode, struct file *file) 62 { 63 return single_open(file, seq_show, inode); 64 } 65 66 static const struct file_operations proc_fdinfo_file_operations = { 67 .open = seq_fdinfo_open, 68 .read = seq_read, 69 .llseek = seq_lseek, 70 .release = single_release, 71 }; 72 73 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) 74 { 75 struct files_struct *files; 76 struct task_struct *task; 77 const struct cred *cred; 78 struct inode *inode; 79 int fd; 80 81 if (flags & LOOKUP_RCU) 82 return -ECHILD; 83 84 inode = dentry->d_inode; 85 task = get_proc_task(inode); 86 fd = proc_fd(inode); 87 88 if (task) { 89 files = get_files_struct(task); 90 if (files) { 91 struct file *file; 92 93 rcu_read_lock(); 94 file = fcheck_files(files, fd); 95 if (file) { 96 unsigned f_mode = file->f_mode; 97 98 rcu_read_unlock(); 99 put_files_struct(files); 100 101 if (task_dumpable(task)) { 102 rcu_read_lock(); 103 cred = __task_cred(task); 104 inode->i_uid = cred->euid; 105 inode->i_gid = cred->egid; 106 rcu_read_unlock(); 107 } else { 108 inode->i_uid = GLOBAL_ROOT_UID; 109 inode->i_gid = GLOBAL_ROOT_GID; 110 } 111 112 if (S_ISLNK(inode->i_mode)) { 113 unsigned i_mode = S_IFLNK; 114 if (f_mode & FMODE_READ) 115 i_mode |= S_IRUSR | S_IXUSR; 116 if (f_mode & FMODE_WRITE) 117 i_mode |= S_IWUSR | S_IXUSR; 118 inode->i_mode = i_mode; 119 } 120 121 security_task_to_inode(task, inode); 122 put_task_struct(task); 123 return 1; 124 } 125 rcu_read_unlock(); 126 put_files_struct(files); 127 } 128 put_task_struct(task); 129 } 130 131 d_drop(dentry); 132 return 0; 133 } 134 135 static const struct dentry_operations tid_fd_dentry_operations = { 136 .d_revalidate = tid_fd_revalidate, 137 .d_delete = pid_delete_dentry, 138 }; 139 140 static int proc_fd_link(struct dentry *dentry, struct path *path) 141 { 142 struct files_struct *files = NULL; 143 struct task_struct *task; 144 int ret = -ENOENT; 145 146 task = get_proc_task(dentry->d_inode); 147 if (task) { 148 files = get_files_struct(task); 149 put_task_struct(task); 150 } 151 152 if (files) { 153 int fd = proc_fd(dentry->d_inode); 154 struct file *fd_file; 155 156 spin_lock(&files->file_lock); 157 fd_file = fcheck_files(files, fd); 158 if (fd_file) { 159 *path = fd_file->f_path; 160 path_get(&fd_file->f_path); 161 ret = 0; 162 } 163 spin_unlock(&files->file_lock); 164 put_files_struct(files); 165 } 166 167 return ret; 168 } 169 170 static struct dentry * 171 proc_fd_instantiate(struct inode *dir, struct dentry *dentry, 172 struct task_struct *task, const void *ptr) 173 { 174 struct dentry *error = ERR_PTR(-ENOENT); 175 unsigned fd = (unsigned long)ptr; 176 struct proc_inode *ei; 177 struct inode *inode; 178 179 inode = proc_pid_make_inode(dir->i_sb, task); 180 if (!inode) 181 goto out; 182 183 ei = PROC_I(inode); 184 ei->fd = fd; 185 186 inode->i_mode = S_IFLNK; 187 inode->i_op = &proc_pid_link_inode_operations; 188 inode->i_size = 64; 189 190 ei->op.proc_get_link = proc_fd_link; 191 192 d_set_d_op(dentry, &tid_fd_dentry_operations); 193 d_add(dentry, inode); 194 195 /* Close the race of the process dying before we return the dentry */ 196 if (tid_fd_revalidate(dentry, 0)) 197 error = NULL; 198 out: 199 return error; 200 } 201 202 static struct dentry *proc_lookupfd_common(struct inode *dir, 203 struct dentry *dentry, 204 instantiate_t instantiate) 205 { 206 struct task_struct *task = get_proc_task(dir); 207 struct dentry *result = ERR_PTR(-ENOENT); 208 unsigned fd = name_to_int(dentry); 209 210 if (!task) 211 goto out_no_task; 212 if (fd == ~0U) 213 goto out; 214 215 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd); 216 out: 217 put_task_struct(task); 218 out_no_task: 219 return result; 220 } 221 222 static int proc_readfd_common(struct file * filp, void * dirent, 223 filldir_t filldir, instantiate_t instantiate) 224 { 225 struct dentry *dentry = filp->f_path.dentry; 226 struct inode *inode = dentry->d_inode; 227 struct task_struct *p = get_proc_task(inode); 228 struct files_struct *files; 229 unsigned int fd, ino; 230 int retval; 231 232 retval = -ENOENT; 233 if (!p) 234 goto out_no_task; 235 retval = 0; 236 237 fd = filp->f_pos; 238 switch (fd) { 239 case 0: 240 if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0) 241 goto out; 242 filp->f_pos++; 243 case 1: 244 ino = parent_ino(dentry); 245 if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0) 246 goto out; 247 filp->f_pos++; 248 default: 249 files = get_files_struct(p); 250 if (!files) 251 goto out; 252 rcu_read_lock(); 253 for (fd = filp->f_pos - 2; 254 fd < files_fdtable(files)->max_fds; 255 fd++, filp->f_pos++) { 256 char name[PROC_NUMBUF]; 257 int len; 258 int rv; 259 260 if (!fcheck_files(files, fd)) 261 continue; 262 rcu_read_unlock(); 263 264 len = snprintf(name, sizeof(name), "%d", fd); 265 rv = proc_fill_cache(filp, dirent, filldir, 266 name, len, instantiate, p, 267 (void *)(unsigned long)fd); 268 if (rv < 0) 269 goto out_fd_loop; 270 rcu_read_lock(); 271 } 272 rcu_read_unlock(); 273 out_fd_loop: 274 put_files_struct(files); 275 } 276 out: 277 put_task_struct(p); 278 out_no_task: 279 return retval; 280 } 281 282 static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir) 283 { 284 return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate); 285 } 286 287 const struct file_operations proc_fd_operations = { 288 .read = generic_read_dir, 289 .readdir = proc_readfd, 290 .llseek = default_llseek, 291 }; 292 293 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, 294 unsigned int flags) 295 { 296 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate); 297 } 298 299 /* 300 * /proc/pid/fd needs a special permission handler so that a process can still 301 * access /proc/self/fd after it has executed a setuid(). 302 */ 303 int proc_fd_permission(struct inode *inode, int mask) 304 { 305 int rv = generic_permission(inode, mask); 306 if (rv == 0) 307 return 0; 308 if (task_pid(current) == proc_pid(inode)) 309 rv = 0; 310 return rv; 311 } 312 313 const struct inode_operations proc_fd_inode_operations = { 314 .lookup = proc_lookupfd, 315 .permission = proc_fd_permission, 316 .setattr = proc_setattr, 317 }; 318 319 static struct dentry * 320 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry, 321 struct task_struct *task, const void *ptr) 322 { 323 struct dentry *error = ERR_PTR(-ENOENT); 324 unsigned fd = (unsigned long)ptr; 325 struct proc_inode *ei; 326 struct inode *inode; 327 328 inode = proc_pid_make_inode(dir->i_sb, task); 329 if (!inode) 330 goto out; 331 332 ei = PROC_I(inode); 333 ei->fd = fd; 334 335 inode->i_mode = S_IFREG | S_IRUSR; 336 inode->i_fop = &proc_fdinfo_file_operations; 337 338 d_set_d_op(dentry, &tid_fd_dentry_operations); 339 d_add(dentry, inode); 340 341 /* Close the race of the process dying before we return the dentry */ 342 if (tid_fd_revalidate(dentry, 0)) 343 error = NULL; 344 out: 345 return error; 346 } 347 348 static struct dentry * 349 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags) 350 { 351 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate); 352 } 353 354 static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir) 355 { 356 return proc_readfd_common(filp, dirent, filldir, 357 proc_fdinfo_instantiate); 358 } 359 360 const struct inode_operations proc_fdinfo_inode_operations = { 361 .lookup = proc_lookupfdinfo, 362 .setattr = proc_setattr, 363 }; 364 365 const struct file_operations proc_fdinfo_operations = { 366 .read = generic_read_dir, 367 .readdir = proc_readfdinfo, 368 .llseek = default_llseek, 369 }; 370