e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 1) // SPDX-License-Identifier: GPL-2.0-only
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 2) /*
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 3) * Ioctl to read verity metadata
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 4) *
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 5) * Copyright 2021 Google LLC
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 6) */
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 7)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 8) #include "fsverity_private.h"
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 9)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 10) #include <linux/backing-dev.h>
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 11) #include <linux/highmem.h>
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 12) #include <linux/sched/signal.h>
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 13) #include <linux/uaccess.h>
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 14)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 15) static int fsverity_read_merkle_tree(struct inode *inode,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 16) const struct fsverity_info *vi,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 17) void __user *buf, u64 offset, int length)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 18) {
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 19) const struct fsverity_operations *vops = inode->i_sb->s_vop;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 20) u64 end_offset;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 21) unsigned int offs_in_page;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 22) pgoff_t index, last_index;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 23) int retval = 0;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 24) int err = 0;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 25)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 26) end_offset = min(offset + length, vi->tree_params.tree_size);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 27) if (offset >= end_offset)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 28) return 0;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 29) offs_in_page = offset_in_page(offset);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 30) last_index = (end_offset - 1) >> PAGE_SHIFT;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 31)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 32) /*
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 33) * Iterate through each Merkle tree page in the requested range and copy
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 34) * the requested portion to userspace. Note that the Merkle tree block
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 35) * size isn't important here, as we are returning a byte stream; i.e.,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 36) * we can just work with pages even if the tree block size != PAGE_SIZE.
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 37) */
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 38) for (index = offset >> PAGE_SHIFT; index <= last_index; index++) {
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 39) unsigned long num_ra_pages =
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 40) min_t(unsigned long, last_index - index + 1,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 41) inode->i_sb->s_bdi->io_pages);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 42) unsigned int bytes_to_copy = min_t(u64, end_offset - offset,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 43) PAGE_SIZE - offs_in_page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 44) struct page *page;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 45) const void *virt;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 46)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 47) page = vops->read_merkle_tree_page(inode, index, num_ra_pages);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 48) if (IS_ERR(page)) {
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 49) err = PTR_ERR(page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 50) fsverity_err(inode,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 51) "Error %d reading Merkle tree page %lu",
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 52) err, index);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 53) break;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 54) }
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 55)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 56) virt = kmap(page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 57) if (copy_to_user(buf, virt + offs_in_page, bytes_to_copy)) {
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 58) kunmap(page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 59) put_page(page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 60) err = -EFAULT;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 61) break;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 62) }
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 63) kunmap(page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 64) put_page(page);
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 65)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 66) retval += bytes_to_copy;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 67) buf += bytes_to_copy;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 68) offset += bytes_to_copy;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 69)
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 70) if (fatal_signal_pending(current)) {
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 71) err = -EINTR;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 72) break;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 73) }
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 74) cond_resched();
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 75) offs_in_page = 0;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 76) }
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 77) return retval ? retval : err;
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 78) }
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 79)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 80) /* Copy the requested portion of the buffer to userspace. */
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 81) static int fsverity_read_buffer(void __user *dst, u64 offset, int length,
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 82) const void *src, size_t src_length)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 83) {
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 84) if (offset >= src_length)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 85) return 0;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 86) src += offset;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 87) src_length -= offset;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 88)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 89) length = min_t(size_t, length, src_length);
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 90)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 91) if (copy_to_user(dst, src, length))
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 92) return -EFAULT;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 93)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 94) return length;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 95) }
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 96)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 97) static int fsverity_read_descriptor(struct inode *inode,
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 98) void __user *buf, u64 offset, int length)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 99) {
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 100) struct fsverity_descriptor *desc;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 101) size_t desc_size;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 102) int res;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 103)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 104) res = fsverity_get_descriptor(inode, &desc, &desc_size);
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 105) if (res)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 106) return res;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 107)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 108) /* don't include the signature */
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 109) desc_size = offsetof(struct fsverity_descriptor, signature);
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 110) desc->sig_size = 0;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 111)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 112) res = fsverity_read_buffer(buf, offset, length, desc, desc_size);
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 113)
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 114) kfree(desc);
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 115) return res;
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 116) }
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 117)
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 118) static int fsverity_read_signature(struct inode *inode,
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 119) void __user *buf, u64 offset, int length)
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 120) {
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 121) struct fsverity_descriptor *desc;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 122) size_t desc_size;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 123) int res;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 124)
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 125) res = fsverity_get_descriptor(inode, &desc, &desc_size);
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 126) if (res)
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 127) return res;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 128)
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 129) if (desc->sig_size == 0) {
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 130) res = -ENODATA;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 131) goto out;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 132) }
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 133)
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 134) /*
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 135) * Include only the signature. Note that fsverity_get_descriptor()
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 136) * already verified that sig_size is in-bounds.
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 137) */
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 138) res = fsverity_read_buffer(buf, offset, length, desc->signature,
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 139) le32_to_cpu(desc->sig_size));
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 140) out:
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 141) kfree(desc);
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 142) return res;
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 143) }
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 144)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 145) /**
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 146) * fsverity_ioctl_read_metadata() - read verity metadata from a file
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 147) * @filp: file to read the metadata from
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 148) * @uarg: user pointer to fsverity_read_metadata_arg
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 149) *
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 150) * Return: length read on success, 0 on EOF, -errno on failure
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 151) */
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 152) int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 153) {
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 154) struct inode *inode = file_inode(filp);
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 155) const struct fsverity_info *vi;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 156) struct fsverity_read_metadata_arg arg;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 157) int length;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 158) void __user *buf;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 159)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 160) vi = fsverity_get_info(inode);
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 161) if (!vi)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 162) return -ENODATA; /* not a verity file */
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 163) /*
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 164) * Note that we don't have to explicitly check that the file is open for
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 165) * reading, since verity files can only be opened for reading.
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 166) */
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 167)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 168) if (copy_from_user(&arg, uarg, sizeof(arg)))
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 169) return -EFAULT;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 170)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 171) if (arg.__reserved)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 172) return -EINVAL;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 173)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 174) /* offset + length must not overflow. */
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 175) if (arg.offset + arg.length < arg.offset)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 176) return -EINVAL;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 177)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 178) /* Ensure that the return value will fit in INT_MAX. */
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 179) length = min_t(u64, arg.length, INT_MAX);
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 180)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 181) buf = u64_to_user_ptr(arg.buf_ptr);
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 182)
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 183) switch (arg.metadata_type) {
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 184) case FS_VERITY_METADATA_TYPE_MERKLE_TREE:
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 185) return fsverity_read_merkle_tree(inode, vi, buf, arg.offset,
622699cfe6ec5 (Eric Biggers 2021-01-15 10:18:17 -0800 186) length);
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 187) case FS_VERITY_METADATA_TYPE_DESCRIPTOR:
947191ac8caba (Eric Biggers 2021-01-15 10:18:18 -0800 188) return fsverity_read_descriptor(inode, buf, arg.offset, length);
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 189) case FS_VERITY_METADATA_TYPE_SIGNATURE:
07c99001312cb (Eric Biggers 2021-01-15 10:18:19 -0800 190) return fsverity_read_signature(inode, buf, arg.offset, length);
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 191) default:
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 192) return -EINVAL;
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 193) }
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 194) }
e17fe6579de02 (Eric Biggers 2021-01-15 10:18:16 -0800 195) EXPORT_SYMBOL_GPL(fsverity_ioctl_read_metadata);
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