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 ret = file->f_op->show_fdinfo(m, file); 57 fput(file); 58 } 59 60 return ret; 61 } 62 63 static int seq_fdinfo_open(struct inode *inode, struct file *file) 64 { 65 return single_open(file, seq_show, inode); 66 } 67 68 static const struct file_operations proc_fdinfo_file_operations = { 69 .open = seq_fdinfo_open, 70 .read = seq_read, 71 .llseek = seq_lseek, 72 .release = single_release, 73 }; 74 75 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) 76 { 77 struct files_struct *files; 78 struct task_struct *task; 79 const struct cred *cred; 80 struct inode *inode; 81 int fd; 82 83 if (flags & LOOKUP_RCU) 84 return -ECHILD; 85 86 inode = dentry->d_inode; 87 task = get_proc_task(inode); 88 fd = proc_fd(inode); 89 90 if (task) { 91 files = get_files_struct(task); 92 if (files) { 93 struct file *file; 94 95 rcu_read_lock(); 96 file = fcheck_files(files, fd); 97 if (file) { 98 unsigned f_mode = file->f_mode; 99 100 rcu_read_unlock(); 101 put_files_struct(files); 102 103 if (task_dumpable(task)) { 104 rcu_read_lock(); 105 cred = __task_cred(task); 106 inode->i_uid = cred->euid; 107 inode->i_gid = cred->egid; 108 rcu_read_unlock(); 109 } else { 110 inode->i_uid = GLOBAL_ROOT_UID; 111 inode->i_gid = GLOBAL_ROOT_GID; 112 } 113 114 if (S_ISLNK(inode->i_mode)) { 115 unsigned i_mode = S_IFLNK; 116 if (f_mode & FMODE_READ) 117 i_mode |= S_IRUSR | S_IXUSR; 118 if (f_mode & FMODE_WRITE) 119 i_mode |= S_IWUSR | S_IXUSR; 120 inode->i_mode = i_mode; 121 } 122 123 security_task_to_inode(task, inode); 124 put_task_struct(task); 125 return 1; 126 } 127 rcu_read_unlock(); 128 put_files_struct(files); 129 } 130 put_task_struct(task); 131 } 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->d_name); 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 files = get_files_struct(p); 234 if (!files) 235 goto out; 236 237 rcu_read_lock(); 238 for (fd = ctx->pos - 2; 239 fd < files_fdtable(files)->max_fds; 240 fd++, ctx->pos++) { 241 char name[PROC_NUMBUF]; 242 int len; 243 244 if (!fcheck_files(files, fd)) 245 continue; 246 rcu_read_unlock(); 247 248 len = snprintf(name, sizeof(name), "%d", fd); 249 if (!proc_fill_cache(file, ctx, 250 name, len, instantiate, p, 251 (void *)(unsigned long)fd)) 252 goto out_fd_loop; 253 rcu_read_lock(); 254 } 255 rcu_read_unlock(); 256 out_fd_loop: 257 put_files_struct(files); 258 out: 259 put_task_struct(p); 260 return 0; 261 } 262 263 static int proc_readfd(struct file *file, struct dir_context *ctx) 264 { 265 return proc_readfd_common(file, ctx, proc_fd_instantiate); 266 } 267 268 const struct file_operations proc_fd_operations = { 269 .read = generic_read_dir, 270 .iterate = proc_readfd, 271 .llseek = default_llseek, 272 }; 273 274 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, 275 unsigned int flags) 276 { 277 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate); 278 } 279 280 /* 281 * /proc/pid/fd needs a special permission handler so that a process can still 282 * access /proc/self/fd after it has executed a setuid(). 283 */ 284 int proc_fd_permission(struct inode *inode, int mask) 285 { 286 int rv = generic_permission(inode, mask); 287 if (rv == 0) 288 return 0; 289 if (task_tgid(current) == proc_pid(inode)) 290 rv = 0; 291 return rv; 292 } 293 294 const struct inode_operations proc_fd_inode_operations = { 295 .lookup = proc_lookupfd, 296 .permission = proc_fd_permission, 297 .setattr = proc_setattr, 298 }; 299 300 static int 301 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry, 302 struct task_struct *task, const void *ptr) 303 { 304 unsigned fd = (unsigned long)ptr; 305 struct proc_inode *ei; 306 struct inode *inode; 307 308 inode = proc_pid_make_inode(dir->i_sb, task); 309 if (!inode) 310 goto out; 311 312 ei = PROC_I(inode); 313 ei->fd = fd; 314 315 inode->i_mode = S_IFREG | S_IRUSR; 316 inode->i_fop = &proc_fdinfo_file_operations; 317 318 d_set_d_op(dentry, &tid_fd_dentry_operations); 319 d_add(dentry, inode); 320 321 /* Close the race of the process dying before we return the dentry */ 322 if (tid_fd_revalidate(dentry, 0)) 323 return 0; 324 out: 325 return -ENOENT; 326 } 327 328 static struct dentry * 329 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags) 330 { 331 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate); 332 } 333 334 static int proc_readfdinfo(struct file *file, struct dir_context *ctx) 335 { 336 return proc_readfd_common(file, ctx, 337 proc_fdinfo_instantiate); 338 } 339 340 const struct inode_operations proc_fdinfo_inode_operations = { 341 .lookup = proc_lookupfdinfo, 342 .setattr = proc_setattr, 343 }; 344 345 const struct file_operations proc_fdinfo_operations = { 346 .read = generic_read_dir, 347 .iterate = proc_readfdinfo, 348 .llseek = default_llseek, 349 }; 350