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