diff options
Diffstat (limited to 'fs/crypto/fname.c')
-rw-r--r-- | fs/crypto/fname.c | 111 |
1 files changed, 76 insertions, 35 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 9b774f4b50c8..ad9f814fdead 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -12,7 +12,7 @@ #include <linux/scatterlist.h> #include <linux/ratelimit.h> -#include <linux/fscrypto.h> +#include "fscrypt_private.h" /** * fname_crypt_complete() - completion callback for filename crypto @@ -159,6 +159,8 @@ static int fname_decrypt(struct inode *inode, static const char *lookup_table = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; +#define BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) + /** * digest_encode() - * @@ -209,7 +211,7 @@ static int digest_decode(const char *src, int len, char *dst) return cp - dst; } -u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen) +u32 fscrypt_fname_encrypted_size(const struct inode *inode, u32 ilen) { int padding = 32; struct fscrypt_info *ci = inode->i_crypt_info; @@ -227,14 +229,17 @@ EXPORT_SYMBOL(fscrypt_fname_encrypted_size); * Allocates an output buffer that is sufficient for the crypto operation * specified by the context and the direction. */ -int fscrypt_fname_alloc_buffer(struct inode *inode, +int fscrypt_fname_alloc_buffer(const struct inode *inode, u32 ilen, struct fscrypt_str *crypto_str) { - unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen); + u32 olen = fscrypt_fname_encrypted_size(inode, ilen); + const u32 max_encoded_len = + max_t(u32, BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE), + 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))); crypto_str->len = olen; - if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2) - olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2; + olen = max(olen, max_encoded_len); + /* * Allocated buffer can hold one more character to null-terminate the * string @@ -266,6 +271,10 @@ EXPORT_SYMBOL(fscrypt_fname_free_buffer); * * The caller must have allocated sufficient memory for the @oname string. * + * If the key is available, we'll decrypt the disk name; otherwise, we'll encode + * it for presentation. Short names are directly base64-encoded, while long + * names are encoded in fscrypt_digested_name format. + * * Return: 0 on success, -errno on failure */ int fscrypt_fname_disk_to_usr(struct inode *inode, @@ -274,7 +283,7 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, struct fscrypt_str *oname) { const struct qstr qname = FSTR_TO_QSTR(iname); - char buf[24]; + struct fscrypt_digested_name digested_name; if (fscrypt_is_dot_dotdot(&qname)) { oname->name[0] = '.'; @@ -289,20 +298,24 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, if (inode->i_crypt_info) return fname_decrypt(inode, iname, oname); - if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { + if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) { oname->len = digest_encode(iname->name, iname->len, oname->name); return 0; } if (hash) { - memcpy(buf, &hash, 4); - memcpy(buf + 4, &minor_hash, 4); + digested_name.hash = hash; + digested_name.minor_hash = minor_hash; } else { - memset(buf, 0, 8); + digested_name.hash = 0; + digested_name.minor_hash = 0; } - memcpy(buf + 8, iname->name + iname->len - 16, 16); + memcpy(digested_name.digest, + FSCRYPT_FNAME_DIGEST(iname->name, iname->len), + FSCRYPT_FNAME_DIGEST_SIZE); oname->name[0] = '_'; - oname->len = 1 + digest_encode(buf, 24, oname->name + 1); + oname->len = 1 + digest_encode((const char *)&digested_name, + sizeof(digested_name), oname->name + 1); return 0; } EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); @@ -332,14 +345,39 @@ int fscrypt_fname_usr_to_disk(struct inode *inode, * in a directory. Consequently, a user space name cannot be mapped to * a disk-space name */ - return -EACCES; + return -ENOKEY; } EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); +/** + * fscrypt_setup_filename() - prepare to search a possibly encrypted directory + * @dir: the directory that will be searched + * @iname: the user-provided filename being searched for + * @lookup: 1 if we're allowed to proceed without the key because it's + * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot + * proceed without the key because we're going to create the dir_entry. + * @fname: the filename information to be filled in + * + * Given a user-provided filename @iname, this function sets @fname->disk_name + * to the name that would be stored in the on-disk directory entry, if possible. + * If the directory is unencrypted this is simply @iname. Else, if we have the + * directory's encryption key, then @iname is the plaintext, so we encrypt it to + * get the disk_name. + * + * Else, for keyless @lookup operations, @iname is the presented ciphertext, so + * we decode it to get either the ciphertext disk_name (for short names) or the + * fscrypt_digested_name (for long names). Non-@lookup operations will be + * impossible in this case, so we fail them with ENOKEY. + * + * If successful, fscrypt_free_filename() must be called later to clean up. + * + * Return: 0 on success, -errno on failure + */ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, int lookup, struct fscrypt_name *fname) { - int ret = 0, bigname = 0; + int ret; + int digested; memset(fname, 0, sizeof(struct fscrypt_name)); fname->usr_fname = iname; @@ -350,7 +388,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, fname->disk_name.len = iname->len; return 0; } - ret = get_crypt_info(dir); + ret = fscrypt_get_encryption_info(dir); if (ret && ret != -EOPNOTSUPP) return ret; @@ -367,31 +405,43 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, return 0; } if (!lookup) - return -EACCES; + return -ENOKEY; /* * We don't have the key and we are doing a lookup; decode the * user-supplied name */ - if (iname->name[0] == '_') - bigname = 1; - if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43))) - return -ENOENT; + if (iname->name[0] == '_') { + if (iname->len != + 1 + BASE64_CHARS(sizeof(struct fscrypt_digested_name))) + return -ENOENT; + digested = 1; + } else { + if (iname->len > + BASE64_CHARS(FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)) + return -ENOENT; + digested = 0; + } - fname->crypto_buf.name = kmalloc(32, GFP_KERNEL); + fname->crypto_buf.name = + kmalloc(max_t(size_t, FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE, + sizeof(struct fscrypt_digested_name)), + GFP_KERNEL); if (fname->crypto_buf.name == NULL) return -ENOMEM; - ret = digest_decode(iname->name + bigname, iname->len - bigname, + ret = digest_decode(iname->name + digested, iname->len - digested, fname->crypto_buf.name); if (ret < 0) { ret = -ENOENT; goto errout; } fname->crypto_buf.len = ret; - if (bigname) { - memcpy(&fname->hash, fname->crypto_buf.name, 4); - memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4); + if (digested) { + const struct fscrypt_digested_name *n = + (const void *)fname->crypto_buf.name; + fname->hash = n->hash; + fname->minor_hash = n->minor_hash; } else { fname->disk_name.name = fname->crypto_buf.name; fname->disk_name.len = fname->crypto_buf.len; @@ -403,12 +453,3 @@ errout: return ret; } EXPORT_SYMBOL(fscrypt_setup_filename); - -void fscrypt_free_filename(struct fscrypt_name *fname) -{ - kfree(fname->crypto_buf.name); - fname->crypto_buf.name = NULL; - fname->usr_fname = NULL; - fname->disk_name.name = NULL; -} -EXPORT_SYMBOL(fscrypt_free_filename); |