| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * security/tomoyo/realpath.c |
| * |
| * Copyright (C) 2005-2011 NTT DATA CORPORATION |
| */ |
| |
| #include "common.h" |
| #include <linux/magic.h> |
| |
| /** |
| * tomoyo_encode2 - Encode binary string to ascii string. |
| * |
| * @str: String in binary format. |
| * @str_len: Size of @str in byte. |
| * |
| * Returns pointer to @str in ascii format on success, NULL otherwise. |
| * |
| * This function uses kzalloc(), so caller must kfree() if this function |
| * didn't return NULL. |
| */ |
| char *tomoyo_encode2(const char *str, int str_len) |
| { |
| int i; |
| int len = 0; |
| const char *p = str; |
| char *cp; |
| char *cp0; |
| |
| if (!p) |
| return NULL; |
| for (i = 0; i < str_len; i++) { |
| const unsigned char c = p[i]; |
| |
| if (c == '\\') |
| len += 2; |
| else if (c > ' ' && c < 127) |
| len++; |
| else |
| len += 4; |
| } |
| len++; |
| /* Reserve space for appending "/". */ |
| cp = kzalloc(len + 10, GFP_NOFS); |
| if (!cp) |
| return NULL; |
| cp0 = cp; |
| p = str; |
| for (i = 0; i < str_len; i++) { |
| const unsigned char c = p[i]; |
| |
| if (c == '\\') { |
| *cp++ = '\\'; |
| *cp++ = '\\'; |
| } else if (c > ' ' && c < 127) { |
| *cp++ = c; |
| } else { |
| *cp++ = '\\'; |
| *cp++ = (c >> 6) + '0'; |
| *cp++ = ((c >> 3) & 7) + '0'; |
| *cp++ = (c & 7) + '0'; |
| } |
| } |
| return cp0; |
| } |
| |
| /** |
| * tomoyo_encode - Encode binary string to ascii string. |
| * |
| * @str: String in binary format. |
| * |
| * Returns pointer to @str in ascii format on success, NULL otherwise. |
| * |
| * This function uses kzalloc(), so caller must kfree() if this function |
| * didn't return NULL. |
| */ |
| char *tomoyo_encode(const char *str) |
| { |
| return str ? tomoyo_encode2(str, strlen(str)) : NULL; |
| } |
| |
| /** |
| * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root. |
| * |
| * @path: Pointer to "struct path". |
| * @buffer: Pointer to buffer to return value in. |
| * @buflen: Sizeof @buffer. |
| * |
| * Returns the buffer on success, an error code otherwise. |
| * |
| * If dentry is a directory, trailing '/' is appended. |
| */ |
| static char *tomoyo_get_absolute_path(const struct path *path, char * const buffer, |
| const int buflen) |
| { |
| char *pos = ERR_PTR(-ENOMEM); |
| |
| if (buflen >= 256) { |
| /* go to whatever namespace root we are under */ |
| pos = d_absolute_path(path, buffer, buflen - 1); |
| if (!IS_ERR(pos) && *pos == '/' && pos[1]) { |
| struct inode *inode = d_backing_inode(path->dentry); |
| |
| if (inode && S_ISDIR(inode->i_mode)) { |
| buffer[buflen - 2] = '/'; |
| buffer[buflen - 1] = '\0'; |
| } |
| } |
| } |
| return pos; |
| } |
| |
| /** |
| * tomoyo_get_dentry_path - Get the path of a dentry. |
| * |
| * @dentry: Pointer to "struct dentry". |
| * @buffer: Pointer to buffer to return value in. |
| * @buflen: Sizeof @buffer. |
| * |
| * Returns the buffer on success, an error code otherwise. |
| * |
| * If dentry is a directory, trailing '/' is appended. |
| */ |
| static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer, |
| const int buflen) |
| { |
| char *pos = ERR_PTR(-ENOMEM); |
| |
| if (buflen >= 256) { |
| pos = dentry_path_raw(dentry, buffer, buflen - 1); |
| if (!IS_ERR(pos) && *pos == '/' && pos[1]) { |
| struct inode *inode = d_backing_inode(dentry); |
| |
| if (inode && S_ISDIR(inode->i_mode)) { |
| buffer[buflen - 2] = '/'; |
| buffer[buflen - 1] = '\0'; |
| } |
| } |
| } |
| return pos; |
| } |
| |
| /** |
| * tomoyo_get_local_path - Get the path of a dentry. |
| * |
| * @dentry: Pointer to "struct dentry". |
| * @buffer: Pointer to buffer to return value in. |
| * @buflen: Sizeof @buffer. |
| * |
| * Returns the buffer on success, an error code otherwise. |
| */ |
| static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer, |
| const int buflen) |
| { |
| struct super_block *sb = dentry->d_sb; |
| char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen); |
| |
| if (IS_ERR(pos)) |
| return pos; |
| /* Convert from $PID to self if $PID is current thread. */ |
| if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') { |
| char *ep; |
| const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10); |
| |
| if (*ep == '/' && pid && pid == |
| task_tgid_nr_ns(current, sb->s_fs_info)) { |
| pos = ep - 5; |
| if (pos < buffer) |
| goto out; |
| memmove(pos, "/self", 5); |
| } |
| goto prepend_filesystem_name; |
| } |
| /* Use filesystem name for unnamed devices. */ |
| if (!MAJOR(sb->s_dev)) |
| goto prepend_filesystem_name; |
| { |
| struct inode *inode = d_backing_inode(sb->s_root); |
| |
| /* |
| * Use filesystem name if filesystem does not support rename() |
| * operation. |
| */ |
| if (!inode->i_op->rename) |
| goto prepend_filesystem_name; |
| } |
| /* Prepend device name. */ |
| { |
| char name[64]; |
| int name_len; |
| const dev_t dev = sb->s_dev; |
| |
| name[sizeof(name) - 1] = '\0'; |
| snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev), |
| MINOR(dev)); |
| name_len = strlen(name); |
| pos -= name_len; |
| if (pos < buffer) |
| goto out; |
| memmove(pos, name, name_len); |
| return pos; |
| } |
| /* Prepend filesystem name. */ |
| prepend_filesystem_name: |
| { |
| const char *name = sb->s_type->name; |
| const int name_len = strlen(name); |
| |
| pos -= name_len + 1; |
| if (pos < buffer) |
| goto out; |
| memmove(pos, name, name_len); |
| pos[name_len] = ':'; |
| } |
| return pos; |
| out: |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| /** |
| * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root. |
| * |
| * @path: Pointer to "struct path". |
| * |
| * Returns the realpath of the given @path on success, NULL otherwise. |
| * |
| * If dentry is a directory, trailing '/' is appended. |
| * Characters out of 0x20 < c < 0x7F range are converted to |
| * \ooo style octal string. |
| * Character \ is converted to \\ string. |
| * |
| * These functions use kzalloc(), so the caller must call kfree() |
| * if these functions didn't return NULL. |
| */ |
| char *tomoyo_realpath_from_path(const struct path *path) |
| { |
| char *buf = NULL; |
| char *name = NULL; |
| unsigned int buf_len = PAGE_SIZE / 2; |
| struct dentry *dentry = path->dentry; |
| struct super_block *sb; |
| |
| if (!dentry) |
| return NULL; |
| sb = dentry->d_sb; |
| while (1) { |
| char *pos; |
| struct inode *inode; |
| |
| buf_len <<= 1; |
| kfree(buf); |
| buf = kmalloc(buf_len, GFP_NOFS); |
| if (!buf) |
| break; |
| /* To make sure that pos is '\0' terminated. */ |
| buf[buf_len - 1] = '\0'; |
| /* For "pipe:[\$]" and "socket:[\$]". */ |
| if (dentry->d_op && dentry->d_op->d_dname) { |
| pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1); |
| goto encode; |
| } |
| inode = d_backing_inode(sb->s_root); |
| /* |
| * Get local name for filesystems without rename() operation |
| * or dentry without vfsmount. |
| */ |
| if (!path->mnt || |
| (!inode->i_op->rename && |
| !(sb->s_type->fs_flags & FS_REQUIRES_DEV))) |
| pos = tomoyo_get_local_path(path->dentry, buf, |
| buf_len - 1); |
| /* Get absolute name for the rest. */ |
| else { |
| pos = tomoyo_get_absolute_path(path, buf, buf_len - 1); |
| /* |
| * Fall back to local name if absolute name is not |
| * available. |
| */ |
| if (pos == ERR_PTR(-EINVAL)) |
| pos = tomoyo_get_local_path(path->dentry, buf, |
| buf_len - 1); |
| } |
| encode: |
| if (IS_ERR(pos)) |
| continue; |
| name = tomoyo_encode(pos); |
| break; |
| } |
| kfree(buf); |
| if (!name) |
| tomoyo_warn_oom(__func__); |
| return name; |
| } |
| |
| /** |
| * tomoyo_realpath_nofollow - Get realpath of a pathname. |
| * |
| * @pathname: The pathname to solve. |
| * |
| * Returns the realpath of @pathname on success, NULL otherwise. |
| */ |
| char *tomoyo_realpath_nofollow(const char *pathname) |
| { |
| struct path path; |
| |
| if (pathname && kern_path(pathname, 0, &path) == 0) { |
| char *buf = tomoyo_realpath_from_path(&path); |
| |
| path_put(&path); |
| return buf; |
| } |
| return NULL; |
| } |