| 1 | #include <linux/compiler.h> |
| 2 | #include <linux/file.h> |
| 3 | #include <linux/fs.h> |
| 4 | #include <linux/linkage.h> |
| 5 | #include <linux/mount.h> |
| 6 | #include <linux/namei.h> |
| 7 | #include <linux/sched.h> |
| 8 | #include <linux/stat.h> |
| 9 | #include <linux/utime.h> |
| 10 | #include <linux/syscalls.h> |
| 11 | #include <asm/uaccess.h> |
| 12 | #include <asm/unistd.h> |
| 13 | |
| 14 | #ifdef __ARCH_WANT_SYS_UTIME |
| 15 | |
| 16 | /* |
| 17 | * sys_utime() can be implemented in user-level using sys_utimes(). |
| 18 | * Is this for backwards compatibility? If so, why not move it |
| 19 | * into the appropriate arch directory (for those architectures that |
| 20 | * need it). |
| 21 | */ |
| 22 | |
| 23 | /* If times==NULL, set access and modification to current time, |
| 24 | * must be owner or have write permission. |
| 25 | * Else, update from *times, must be owner or super user. |
| 26 | */ |
| 27 | SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times) |
| 28 | { |
| 29 | struct timespec tv[2]; |
| 30 | |
| 31 | if (times) { |
| 32 | if (get_user(tv[0].tv_sec, ×->actime) || |
| 33 | get_user(tv[1].tv_sec, ×->modtime)) |
| 34 | return -EFAULT; |
| 35 | tv[0].tv_nsec = 0; |
| 36 | tv[1].tv_nsec = 0; |
| 37 | } |
| 38 | return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0); |
| 39 | } |
| 40 | |
| 41 | #endif |
| 42 | |
| 43 | static bool nsec_valid(long nsec) |
| 44 | { |
| 45 | if (nsec == UTIME_OMIT || nsec == UTIME_NOW) |
| 46 | return true; |
| 47 | |
| 48 | return nsec >= 0 && nsec <= 999999999; |
| 49 | } |
| 50 | |
| 51 | static int utimes_common(struct path *path, struct timespec *times) |
| 52 | { |
| 53 | int error; |
| 54 | struct iattr newattrs; |
| 55 | struct inode *inode = path->dentry->d_inode; |
| 56 | |
| 57 | error = mnt_want_write(path->mnt); |
| 58 | if (error) |
| 59 | goto out; |
| 60 | |
| 61 | if (times && times[0].tv_nsec == UTIME_NOW && |
| 62 | times[1].tv_nsec == UTIME_NOW) |
| 63 | times = NULL; |
| 64 | |
| 65 | newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME; |
| 66 | if (times) { |
| 67 | if (times[0].tv_nsec == UTIME_OMIT) |
| 68 | newattrs.ia_valid &= ~ATTR_ATIME; |
| 69 | else if (times[0].tv_nsec != UTIME_NOW) { |
| 70 | newattrs.ia_atime.tv_sec = times[0].tv_sec; |
| 71 | newattrs.ia_atime.tv_nsec = times[0].tv_nsec; |
| 72 | newattrs.ia_valid |= ATTR_ATIME_SET; |
| 73 | } |
| 74 | |
| 75 | if (times[1].tv_nsec == UTIME_OMIT) |
| 76 | newattrs.ia_valid &= ~ATTR_MTIME; |
| 77 | else if (times[1].tv_nsec != UTIME_NOW) { |
| 78 | newattrs.ia_mtime.tv_sec = times[1].tv_sec; |
| 79 | newattrs.ia_mtime.tv_nsec = times[1].tv_nsec; |
| 80 | newattrs.ia_valid |= ATTR_MTIME_SET; |
| 81 | } |
| 82 | /* |
| 83 | * Tell inode_change_ok(), that this is an explicit time |
| 84 | * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET |
| 85 | * were used. |
| 86 | */ |
| 87 | newattrs.ia_valid |= ATTR_TIMES_SET; |
| 88 | } else { |
| 89 | /* |
| 90 | * If times is NULL (or both times are UTIME_NOW), |
| 91 | * then we need to check permissions, because |
| 92 | * inode_change_ok() won't do it. |
| 93 | */ |
| 94 | error = -EACCES; |
| 95 | if (IS_IMMUTABLE(inode)) |
| 96 | goto mnt_drop_write_and_out; |
| 97 | |
| 98 | if (!inode_owner_or_capable(inode)) { |
| 99 | error = inode_permission(inode, MAY_WRITE); |
| 100 | if (error) |
| 101 | goto mnt_drop_write_and_out; |
| 102 | } |
| 103 | } |
| 104 | mutex_lock(&inode->i_mutex); |
| 105 | error = notify_change(path->dentry, &newattrs); |
| 106 | mutex_unlock(&inode->i_mutex); |
| 107 | |
| 108 | mnt_drop_write_and_out: |
| 109 | mnt_drop_write(path->mnt); |
| 110 | out: |
| 111 | return error; |
| 112 | } |
| 113 | |
| 114 | /* |
| 115 | * do_utimes - change times on filename or file descriptor |
| 116 | * @dfd: open file descriptor, -1 or AT_FDCWD |
| 117 | * @filename: path name or NULL |
| 118 | * @times: new times or NULL |
| 119 | * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment) |
| 120 | * |
| 121 | * If filename is NULL and dfd refers to an open file, then operate on |
| 122 | * the file. Otherwise look up filename, possibly using dfd as a |
| 123 | * starting point. |
| 124 | * |
| 125 | * If times==NULL, set access and modification to current time, |
| 126 | * must be owner or have write permission. |
| 127 | * Else, update from *times, must be owner or super user. |
| 128 | */ |
| 129 | long do_utimes(int dfd, const char __user *filename, struct timespec *times, |
| 130 | int flags) |
| 131 | { |
| 132 | int error = -EINVAL; |
| 133 | |
| 134 | if (times && (!nsec_valid(times[0].tv_nsec) || |
| 135 | !nsec_valid(times[1].tv_nsec))) { |
| 136 | goto out; |
| 137 | } |
| 138 | |
| 139 | if (flags & ~AT_SYMLINK_NOFOLLOW) |
| 140 | goto out; |
| 141 | |
| 142 | if (filename == NULL && dfd != AT_FDCWD) { |
| 143 | struct file *file; |
| 144 | |
| 145 | if (flags & AT_SYMLINK_NOFOLLOW) |
| 146 | goto out; |
| 147 | |
| 148 | file = fget(dfd); |
| 149 | error = -EBADF; |
| 150 | if (!file) |
| 151 | goto out; |
| 152 | |
| 153 | error = utimes_common(&file->f_path, times); |
| 154 | fput(file); |
| 155 | } else { |
| 156 | struct path path; |
| 157 | int lookup_flags = 0; |
| 158 | |
| 159 | if (!(flags & AT_SYMLINK_NOFOLLOW)) |
| 160 | lookup_flags |= LOOKUP_FOLLOW; |
| 161 | |
| 162 | error = user_path_at(dfd, filename, lookup_flags, &path); |
| 163 | if (error) |
| 164 | goto out; |
| 165 | |
| 166 | error = utimes_common(&path, times); |
| 167 | path_put(&path); |
| 168 | } |
| 169 | |
| 170 | out: |
| 171 | return error; |
| 172 | } |
| 173 | |
| 174 | SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename, |
| 175 | struct timespec __user *, utimes, int, flags) |
| 176 | { |
| 177 | struct timespec tstimes[2]; |
| 178 | |
| 179 | if (utimes) { |
| 180 | if (copy_from_user(&tstimes, utimes, sizeof(tstimes))) |
| 181 | return -EFAULT; |
| 182 | |
| 183 | /* Nothing to do, we must not even check the path. */ |
| 184 | if (tstimes[0].tv_nsec == UTIME_OMIT && |
| 185 | tstimes[1].tv_nsec == UTIME_OMIT) |
| 186 | return 0; |
| 187 | } |
| 188 | |
| 189 | return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags); |
| 190 | } |
| 191 | |
| 192 | SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename, |
| 193 | struct timeval __user *, utimes) |
| 194 | { |
| 195 | struct timeval times[2]; |
| 196 | struct timespec tstimes[2]; |
| 197 | |
| 198 | if (utimes) { |
| 199 | if (copy_from_user(×, utimes, sizeof(times))) |
| 200 | return -EFAULT; |
| 201 | |
| 202 | /* This test is needed to catch all invalid values. If we |
| 203 | would test only in do_utimes we would miss those invalid |
| 204 | values truncated by the multiplication with 1000. Note |
| 205 | that we also catch UTIME_{NOW,OMIT} here which are only |
| 206 | valid for utimensat. */ |
| 207 | if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 || |
| 208 | times[1].tv_usec >= 1000000 || times[1].tv_usec < 0) |
| 209 | return -EINVAL; |
| 210 | |
| 211 | tstimes[0].tv_sec = times[0].tv_sec; |
| 212 | tstimes[0].tv_nsec = 1000 * times[0].tv_usec; |
| 213 | tstimes[1].tv_sec = times[1].tv_sec; |
| 214 | tstimes[1].tv_nsec = 1000 * times[1].tv_usec; |
| 215 | } |
| 216 | |
| 217 | return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0); |
| 218 | } |
| 219 | |
| 220 | SYSCALL_DEFINE2(utimes, char __user *, filename, |
| 221 | struct timeval __user *, utimes) |
| 222 | { |
| 223 | return sys_futimesat(AT_FDCWD, filename, utimes); |
| 224 | } |