1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/sched/signal.h> 3 #include <linux/errno.h> 4 #include <linux/dcache.h> 5 #include <linux/path.h> 6 #include <linux/fdtable.h> 7 #include <linux/namei.h> 8 #include <linux/pid.h> 9 #include <linux/security.h> 10 #include <linux/file.h> 11 #include <linux/seq_file.h> 12 #include <linux/fs.h> 13 14 #include <linux/proc_fs.h> 15 16 #include "../mount.h" 17 #include "internal.h" 18 #include "fd.h" 19 20 static int seq_show(struct seq_file *m, void *v) 21 { 22 struct files_struct *files = NULL; 23 int f_flags = 0, ret = -ENOENT; 24 struct file *file = NULL; 25 struct task_struct *task; 26 27 task = get_proc_task(m->private); 28 if (!task) 29 return -ENOENT; 30 31 files = get_files_struct(task); 32 put_task_struct(task); 33 34 if (files) { 35 unsigned int fd = proc_fd(m->private); 36 37 spin_lock(&files->file_lock); 38 file = fcheck_files(files, fd); 39 if (file) { 40 struct fdtable *fdt = files_fdtable(files); 41 42 f_flags = file->f_flags; 43 if (close_on_exec(fd, fdt)) 44 f_flags |= O_CLOEXEC; 45 46 get_file(file); 47 ret = 0; 48 } 49 spin_unlock(&files->file_lock); 50 put_files_struct(files); 51 } 52 53 if (ret) 54 return ret; 55 56 seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n", 57 (long long)file->f_pos, f_flags, 58 real_mount(file->f_path.mnt)->mnt_id); 59 60 show_fd_locks(m, file, files); 61 if (seq_has_overflowed(m)) 62 goto out; 63 64 if (file->f_op->show_fdinfo) 65 file->f_op->show_fdinfo(m, file); 66 67 out: 68 fput(file); 69 return 0; 70 } 71 72 static int seq_fdinfo_open(struct inode *inode, struct file *file) 73 { 74 return single_open(file, seq_show, inode); 75 } 76 77 static const struct file_operations proc_fdinfo_file_operations = { 78 .open = seq_fdinfo_open, 79 .read = seq_read, 80 .llseek = seq_lseek, 81 .release = single_release, 82 }; 83 84 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags) 85 { 86 struct files_struct *files; 87 struct task_struct *task; 88 struct inode *inode; 89 unsigned 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 task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid); 112 113 if (S_ISLNK(inode->i_mode)) { 114 unsigned i_mode = S_IFLNK; 115 if (f_mode & FMODE_READ) 116 i_mode |= S_IRUSR | S_IXUSR; 117 if (f_mode & FMODE_WRITE) 118 i_mode |= S_IWUSR | S_IXUSR; 119 inode->i_mode = i_mode; 120 } 121 122 security_task_to_inode(task, inode); 123 put_task_struct(task); 124 return 1; 125 } 126 rcu_read_unlock(); 127 put_files_struct(files); 128 } 129 put_task_struct(task); 130 } 131 return 0; 132 } 133 134 static const struct dentry_operations tid_fd_dentry_operations = { 135 .d_revalidate = tid_fd_revalidate, 136 .d_delete = pid_delete_dentry, 137 }; 138 139 static int proc_fd_link(struct dentry *dentry, struct path *path) 140 { 141 struct files_struct *files = NULL; 142 struct task_struct *task; 143 int ret = -ENOENT; 144 145 task = get_proc_task(d_inode(dentry)); 146 if (task) { 147 files = get_files_struct(task); 148 put_task_struct(task); 149 } 150 151 if (files) { 152 unsigned int fd = proc_fd(d_inode(dentry)); 153 struct file *fd_file; 154 155 spin_lock(&files->file_lock); 156 fd_file = fcheck_files(files, fd); 157 if (fd_file) { 158 *path = fd_file->f_path; 159 path_get(&fd_file->f_path); 160 ret = 0; 161 } 162 spin_unlock(&files->file_lock); 163 put_files_struct(files); 164 } 165 166 return ret; 167 } 168 169 static int 170 proc_fd_instantiate(struct inode *dir, struct dentry *dentry, 171 struct task_struct *task, const void *ptr) 172 { 173 unsigned fd = (unsigned long)ptr; 174 struct proc_inode *ei; 175 struct inode *inode; 176 177 inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK); 178 if (!inode) 179 goto out; 180 181 ei = PROC_I(inode); 182 ei->fd = fd; 183 184 inode->i_op = &proc_pid_link_inode_operations; 185 inode->i_size = 64; 186 187 ei->op.proc_get_link = proc_fd_link; 188 189 d_set_d_op(dentry, &tid_fd_dentry_operations); 190 d_add(dentry, inode); 191 192 /* Close the race of the process dying before we return the dentry */ 193 if (tid_fd_revalidate(dentry, 0)) 194 return 0; 195 out: 196 return -ENOENT; 197 } 198 199 static struct dentry *proc_lookupfd_common(struct inode *dir, 200 struct dentry *dentry, 201 instantiate_t instantiate) 202 { 203 struct task_struct *task = get_proc_task(dir); 204 int result = -ENOENT; 205 unsigned fd = name_to_int(&dentry->d_name); 206 207 if (!task) 208 goto out_no_task; 209 if (fd == ~0U) 210 goto out; 211 212 result = instantiate(dir, dentry, task, (void *)(unsigned long)fd); 213 out: 214 put_task_struct(task); 215 out_no_task: 216 return ERR_PTR(result); 217 } 218 219 static int proc_readfd_common(struct file *file, struct dir_context *ctx, 220 instantiate_t instantiate) 221 { 222 struct task_struct *p = get_proc_task(file_inode(file)); 223 struct files_struct *files; 224 unsigned int fd; 225 226 if (!p) 227 return -ENOENT; 228 229 if (!dir_emit_dots(file, ctx)) 230 goto out; 231 files = get_files_struct(p); 232 if (!files) 233 goto out; 234 235 rcu_read_lock(); 236 for (fd = ctx->pos - 2; 237 fd < files_fdtable(files)->max_fds; 238 fd++, ctx->pos++) { 239 char name[10 + 1]; 240 int len; 241 242 if (!fcheck_files(files, fd)) 243 continue; 244 rcu_read_unlock(); 245 246 len = snprintf(name, sizeof(name), "%u", fd); 247 if (!proc_fill_cache(file, ctx, 248 name, len, instantiate, p, 249 (void *)(unsigned long)fd)) 250 goto out_fd_loop; 251 cond_resched(); 252 rcu_read_lock(); 253 } 254 rcu_read_unlock(); 255 out_fd_loop: 256 put_files_struct(files); 257 out: 258 put_task_struct(p); 259 return 0; 260 } 261 262 static int proc_readfd(struct file *file, struct dir_context *ctx) 263 { 264 return proc_readfd_common(file, ctx, proc_fd_instantiate); 265 } 266 267 const struct file_operations proc_fd_operations = { 268 .read = generic_read_dir, 269 .iterate_shared = proc_readfd, 270 .llseek = generic_file_llseek, 271 }; 272 273 static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, 274 unsigned int flags) 275 { 276 return proc_lookupfd_common(dir, dentry, proc_fd_instantiate); 277 } 278 279 /* 280 * /proc/pid/fd needs a special permission handler so that a process can still 281 * access /proc/self/fd after it has executed a setuid(). 282 */ 283 int proc_fd_permission(struct inode *inode, int mask) 284 { 285 struct task_struct *p; 286 int rv; 287 288 rv = generic_permission(inode, mask); 289 if (rv == 0) 290 return rv; 291 292 rcu_read_lock(); 293 p = pid_task(proc_pid(inode), PIDTYPE_PID); 294 if (p && same_thread_group(p, current)) 295 rv = 0; 296 rcu_read_unlock(); 297 298 return rv; 299 } 300 301 const struct inode_operations proc_fd_inode_operations = { 302 .lookup = proc_lookupfd, 303 .permission = proc_fd_permission, 304 .setattr = proc_setattr, 305 }; 306 307 static int 308 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry, 309 struct task_struct *task, const void *ptr) 310 { 311 unsigned fd = (unsigned long)ptr; 312 struct proc_inode *ei; 313 struct inode *inode; 314 315 inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR); 316 if (!inode) 317 goto out; 318 319 ei = PROC_I(inode); 320 ei->fd = fd; 321 322 inode->i_fop = &proc_fdinfo_file_operations; 323 324 d_set_d_op(dentry, &tid_fd_dentry_operations); 325 d_add(dentry, inode); 326 327 /* Close the race of the process dying before we return the dentry */ 328 if (tid_fd_revalidate(dentry, 0)) 329 return 0; 330 out: 331 return -ENOENT; 332 } 333 334 static struct dentry * 335 proc_lookupfdinfo(struct inode *dir, struct dentry *dentry, unsigned int flags) 336 { 337 return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate); 338 } 339 340 static int proc_readfdinfo(struct file *file, struct dir_context *ctx) 341 { 342 return proc_readfd_common(file, ctx, 343 proc_fdinfo_instantiate); 344 } 345 346 const struct inode_operations proc_fdinfo_inode_operations = { 347 .lookup = proc_lookupfdinfo, 348 .setattr = proc_setattr, 349 }; 350 351 const struct file_operations proc_fdinfo_operations = { 352 .read = generic_read_dir, 353 .iterate_shared = proc_readfdinfo, 354 .llseek = generic_file_llseek, 355 }; 356