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 int 171 proc_fd_instantiate(struct inode *dir, struct dentry *dentry, 172 struct task_struct *task, const void *ptr) 173 { 174 unsigned fd = (unsigned long)ptr; 175 struct proc_inode *ei; 176 struct inode *inode; 177 178 inode = proc_pid_make_inode(dir->i_sb, task); 179 if (!inode) 180 goto out; 181 182 ei = PROC_I(inode); 183 ei->fd = fd; 184 185 inode->i_mode = S_IFLNK; 186 inode->i_op = &proc_pid_link_inode_operations; 187 inode->i_size = 64; 188 189 ei->op.proc_get_link = proc_fd_link; 190 191 d_set_d_op(dentry, &tid_fd_dentry_operations); 192 d_add(dentry, inode); 193 194 /* Close the race of the process dying before we return the dentry */ 195 if (tid_fd_revalidate(dentry, 0)) 196 return 0; 197 out: 198 return -ENOENT; 199 } 200 201 static struct dentry *proc_lookupfd_common(struct inode *dir, 202 struct dentry *dentry, 203 instantiate_t instantiate) 204 { 205 struct task_struct *task = get_proc_task(dir); 206 int result = -ENOENT; 207 unsigned fd = name_to_int(dentry); 208 209 if (!task) 210 goto out_no_task; 211 if (fd == ~0U) 212 goto out; 213 214 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd); 215 out: 216 put_task_struct(task); 217 out_no_task: 218 return ERR_PTR(result); 219 } 220 221 static int proc_readfd_common(struct file *file, struct dir_context *ctx, 222 instantiate_t instantiate) 223 { 224 struct task_struct *p = get_proc_task(file_inode(file)); 225 struct files_struct *files; 226 unsigned int fd; 227 228 if (!p) 229 return -ENOENT; 230 231 if (!dir_emit_dots(file, ctx)) 232 goto out; 233 if (!dir_emit_dots(file, ctx)) 234 goto out; 235 files = get_files_struct(p); 236 if (!files) 237 goto out; 238 239 rcu_read_lock(); 240 for (fd = ctx->pos - 2; 241 fd < files_fdtable(files)->max_fds; 242 fd++, ctx->pos++) { 243 char name[PROC_NUMBUF]; 244 int len; 245 246 if (!fcheck_files(files, fd)) 247 continue; 248 rcu_read_unlock(); 249 250 len = snprintf(name, sizeof(name), "%d", fd); 251 if (!proc_fill_cache(file, ctx, 252 name, len, instantiate, p, 253 (void *)(unsigned long)fd)) 254 goto out_fd_loop; 255 rcu_read_lock(); 256 } 257 rcu_read_unlock(); 258 out_fd_loop: 259 put_files_struct(files); 260 out: 261 put_task_struct(p); 262 return 0; 263 } 264 265 static int proc_readfd(struct file *file, struct dir_context *ctx) 266 { 267 return proc_readfd_common(file, ctx, proc_fd_instantiate); 268 } 269 270 const struct file_operations proc_fd_operations = { 271 .read = generic_read_dir, 272 .iterate = proc_readfd, 273 .llseek = default_llseek, 274 }; 275 276 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, 277 unsigned int flags) 278 { 279 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate); 280 } 281 282 /* 283 * /proc/pid/fd needs a special permission handler so that a process can still 284 * access /proc/self/fd after it has executed a setuid(). 285 */ 286 int proc_fd_permission(struct inode *inode, int mask) 287 { 288 int rv = generic_permission(inode, mask); 289 if (rv == 0) 290 return 0; 291 if (task_pid(current) == proc_pid(inode)) 292 rv = 0; 293 return rv; 294 } 295 296 const struct inode_operations proc_fd_inode_operations = { 297 .lookup = proc_lookupfd, 298 .permission = proc_fd_permission, 299 .setattr = proc_setattr, 300 }; 301 302 static int 303 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry, 304 struct task_struct *task, const void *ptr) 305 { 306 unsigned fd = (unsigned long)ptr; 307 struct proc_inode *ei; 308 struct inode *inode; 309 310 inode = proc_pid_make_inode(dir->i_sb, task); 311 if (!inode) 312 goto out; 313 314 ei = PROC_I(inode); 315 ei->fd = fd; 316 317 inode->i_mode = S_IFREG | S_IRUSR; 318 inode->i_fop = &proc_fdinfo_file_operations; 319 320 d_set_d_op(dentry, &tid_fd_dentry_operations); 321 d_add(dentry, inode); 322 323 /* Close the race of the process dying before we return the dentry */ 324 if (tid_fd_revalidate(dentry, 0)) 325 return 0; 326 out: 327 return -ENOENT; 328 } 329 330 static struct dentry * 331 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags) 332 { 333 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate); 334 } 335 336 static int proc_readfdinfo(struct file *file, struct dir_context *ctx) 337 { 338 return proc_readfd_common(file, ctx, 339 proc_fdinfo_instantiate); 340 } 341 342 const struct inode_operations proc_fdinfo_inode_operations = { 343 .lookup = proc_lookupfdinfo, 344 .setattr = proc_setattr, 345 }; 346 347 const struct file_operations proc_fdinfo_operations = { 348 .read = generic_read_dir, 349 .iterate = proc_readfdinfo, 350 .llseek = default_llseek, 351 }; 352