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