1 #include <linux/sched/signal.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 unsigned 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 struct inode *inode; 88 unsigned int fd; 89 90 if (flags & LOOKUP_RCU) 91 return -ECHILD; 92 93 inode = d_inode(dentry); 94 task = get_proc_task(inode); 95 fd = proc_fd(inode); 96 97 if (task) { 98 files = get_files_struct(task); 99 if (files) { 100 struct file *file; 101 102 rcu_read_lock(); 103 file = fcheck_files(files, fd); 104 if (file) { 105 unsigned f_mode = file->f_mode; 106 107 rcu_read_unlock(); 108 put_files_struct(files); 109 110 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid); 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 return 0; 131 } 132 133 static const struct dentry_operations tid_fd_dentry_operations = { 134 .d_revalidate = tid_fd_revalidate, 135 .d_delete = pid_delete_dentry, 136 }; 137 138 static int proc_fd_link(struct dentry *dentry, struct path *path) 139 { 140 struct files_struct *files = NULL; 141 struct task_struct *task; 142 int ret = -ENOENT; 143 144 task = get_proc_task(d_inode(dentry)); 145 if (task) { 146 files = get_files_struct(task); 147 put_task_struct(task); 148 } 149 150 if (files) { 151 unsigned int fd = proc_fd(d_inode(dentry)); 152 struct file *fd_file; 153 154 spin_lock(&files->file_lock); 155 fd_file = fcheck_files(files, fd); 156 if (fd_file) { 157 *path = fd_file->f_path; 158 path_get(&fd_file->f_path); 159 ret = 0; 160 } 161 spin_unlock(&files->file_lock); 162 put_files_struct(files); 163 } 164 165 return ret; 166 } 167 168 static int 169 proc_fd_instantiate(struct inode *dir, struct dentry *dentry, 170 struct task_struct *task, const void *ptr) 171 { 172 unsigned fd = (unsigned long)ptr; 173 struct proc_inode *ei; 174 struct inode *inode; 175 176 inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK); 177 if (!inode) 178 goto out; 179 180 ei = PROC_I(inode); 181 ei->fd = fd; 182 183 inode->i_op = &proc_pid_link_inode_operations; 184 inode->i_size = 64; 185 186 ei->op.proc_get_link = proc_fd_link; 187 188 d_set_d_op(dentry, &tid_fd_dentry_operations); 189 d_add(dentry, inode); 190 191 /* Close the race of the process dying before we return the dentry */ 192 if (tid_fd_revalidate(dentry, 0)) 193 return 0; 194 out: 195 return -ENOENT; 196 } 197 198 static struct dentry *proc_lookupfd_common(struct inode *dir, 199 struct dentry *dentry, 200 instantiate_t instantiate) 201 { 202 struct task_struct *task = get_proc_task(dir); 203 int result = -ENOENT; 204 unsigned fd = name_to_int(&dentry->d_name); 205 206 if (!task) 207 goto out_no_task; 208 if (fd == ~0U) 209 goto out; 210 211 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd); 212 out: 213 put_task_struct(task); 214 out_no_task: 215 return ERR_PTR(result); 216 } 217 218 static int proc_readfd_common(struct file *file, struct dir_context *ctx, 219 instantiate_t instantiate) 220 { 221 struct task_struct *p = get_proc_task(file_inode(file)); 222 struct files_struct *files; 223 unsigned int fd; 224 225 if (!p) 226 return -ENOENT; 227 228 if (!dir_emit_dots(file, ctx)) 229 goto out; 230 files = get_files_struct(p); 231 if (!files) 232 goto out; 233 234 rcu_read_lock(); 235 for (fd = ctx->pos - 2; 236 fd < files_fdtable(files)->max_fds; 237 fd++, ctx->pos++) { 238 char name[PROC_NUMBUF]; 239 int len; 240 241 if (!fcheck_files(files, fd)) 242 continue; 243 rcu_read_unlock(); 244 245 len = snprintf(name, sizeof(name), "%u", fd); 246 if (!proc_fill_cache(file, ctx, 247 name, len, instantiate, p, 248 (void *)(unsigned long)fd)) 249 goto out_fd_loop; 250 cond_resched(); 251 rcu_read_lock(); 252 } 253 rcu_read_unlock(); 254 out_fd_loop: 255 put_files_struct(files); 256 out: 257 put_task_struct(p); 258 return 0; 259 } 260 261 static int proc_readfd(struct file *file, struct dir_context *ctx) 262 { 263 return proc_readfd_common(file, ctx, proc_fd_instantiate); 264 } 265 266 const struct file_operations proc_fd_operations = { 267 .read = generic_read_dir, 268 .iterate_shared = proc_readfd, 269 .llseek = generic_file_llseek, 270 }; 271 272 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, 273 unsigned int flags) 274 { 275 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate); 276 } 277 278 /* 279 * /proc/pid/fd needs a special permission handler so that a process can still 280 * access /proc/self/fd after it has executed a setuid(). 281 */ 282 int proc_fd_permission(struct inode *inode, int mask) 283 { 284 struct task_struct *p; 285 int rv; 286 287 rv = generic_permission(inode, mask); 288 if (rv == 0) 289 return rv; 290 291 rcu_read_lock(); 292 p = pid_task(proc_pid(inode), PIDTYPE_PID); 293 if (p && same_thread_group(p, current)) 294 rv = 0; 295 rcu_read_unlock(); 296 297 return rv; 298 } 299 300 const struct inode_operations proc_fd_inode_operations = { 301 .lookup = proc_lookupfd, 302 .permission = proc_fd_permission, 303 .setattr = proc_setattr, 304 }; 305 306 static int 307 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry, 308 struct task_struct *task, const void *ptr) 309 { 310 unsigned fd = (unsigned long)ptr; 311 struct proc_inode *ei; 312 struct inode *inode; 313 314 inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR); 315 if (!inode) 316 goto out; 317 318 ei = PROC_I(inode); 319 ei->fd = fd; 320 321 inode->i_fop = &proc_fdinfo_file_operations; 322 323 d_set_d_op(dentry, &tid_fd_dentry_operations); 324 d_add(dentry, inode); 325 326 /* Close the race of the process dying before we return the dentry */ 327 if (tid_fd_revalidate(dentry, 0)) 328 return 0; 329 out: 330 return -ENOENT; 331 } 332 333 static struct dentry * 334 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags) 335 { 336 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate); 337 } 338 339 static int proc_readfdinfo(struct file *file, struct dir_context *ctx) 340 { 341 return proc_readfd_common(file, ctx, 342 proc_fdinfo_instantiate); 343 } 344 345 const struct inode_operations proc_fdinfo_inode_operations = { 346 .lookup = proc_lookupfdinfo, 347 .setattr = proc_setattr, 348 }; 349 350 const struct file_operations proc_fdinfo_operations = { 351 .read = generic_read_dir, 352 .iterate_shared = proc_readfdinfo, 353 .llseek = generic_file_llseek, 354 }; 355