diff options
Diffstat (limited to 'security/tomoyo/realpath.c')
| -rw-r--r-- | security/tomoyo/realpath.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c new file mode 100644 index 00000000..a339187c --- /dev/null +++ b/security/tomoyo/realpath.c @@ -0,0 +1,183 @@ +/* + * security/tomoyo/realpath.c + * + * Pathname calculation functions for TOMOYO. + * + * Copyright (C) 2005-2010 NTT DATA CORPORATION + */ + +#include <linux/types.h> +#include <linux/mount.h> +#include <linux/mnt_namespace.h> +#include <linux/fs_struct.h> +#include <linux/magic.h> +#include <linux/slab.h> +#include <net/sock.h> +#include "common.h" +#include "../../fs/internal.h" + +/** + * tomoyo_encode: Convert 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) +{ + int len = 0; + const char *p = str; + char *cp; + char *cp0; + + if (!p) + return NULL; + while (*p) { + const unsigned char c = *p++; + 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; + while (*p) { + const unsigned char c = *p++; + + 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_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(struct path *path) +{ + char *buf = NULL; + char *name = NULL; + unsigned int buf_len = PAGE_SIZE / 2; + struct dentry *dentry = path->dentry; + bool is_dir; + if (!dentry) + return NULL; + is_dir = dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode); + while (1) { + char *pos; + buf_len <<= 1; + kfree(buf); + buf = kmalloc(buf_len, GFP_NOFS); + if (!buf) + break; + /* Get better name for socket. */ + if (dentry->d_sb && dentry->d_sb->s_magic == SOCKFS_MAGIC) { + struct inode *inode = dentry->d_inode; + struct socket *sock = inode ? SOCKET_I(inode) : NULL; + struct sock *sk = sock ? sock->sk : NULL; + if (sk) { + snprintf(buf, buf_len - 1, "socket:[family=%u:" + "type=%u:protocol=%u]", sk->sk_family, + sk->sk_type, sk->sk_protocol); + } else { + snprintf(buf, buf_len - 1, "socket:[unknown]"); + } + name = tomoyo_encode(buf); + break; + } + /* For "socket:[\$]" and "pipe:[\$]". */ + if (dentry->d_op && dentry->d_op->d_dname) { + pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1); + if (IS_ERR(pos)) + continue; + name = tomoyo_encode(pos); + break; + } + /* If we don't have a vfsmount, we can't calculate. */ + if (!path->mnt) + break; + pos = d_absolute_path(path, buf, buf_len - 1); + /* If path is disconnected, use "[unknown]" instead. */ + if (pos == ERR_PTR(-EINVAL)) { + name = tomoyo_encode("[unknown]"); + break; + } + /* Prepend "/proc" prefix if using internal proc vfs mount. */ + if (!IS_ERR(pos) && (path->mnt->mnt_flags & MNT_INTERNAL) && + (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) { + pos -= 5; + if (pos >= buf) + memcpy(pos, "/proc", 5); + else + pos = ERR_PTR(-ENOMEM); + } + if (IS_ERR(pos)) + continue; + name = tomoyo_encode(pos); + break; + } + kfree(buf); + if (!name) + tomoyo_warn_oom(__func__); + else if (is_dir && *name) { + /* Append trailing '/' if dentry is a directory. */ + char *pos = name + strlen(name) - 1; + if (*pos != '/') + /* + * This is OK because tomoyo_encode() reserves space + * for appending "/". + */ + *++pos = '/'; + } + 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; +} |