pstore/ram: Strip ramoops header for correct decompression
pstore compression/decompression was added during 3.12. The ramoops driver prepends a "====timestamp.timestamp-C|D\n" header to the compressed record before handing it over to pstore driver which doesn't know about the header. In pstore_decompress(), the pstore driver reads the first "==" as a zlib header, so the decompression always fails. For example, this causes the driver to write /dev/pstore/dmesg-ramoops-0.enc.z instead of /dev/pstore/dmesg-ramoops-0. This patch makes the ramoops driver remove the header before pstore decompression. Signed-off-by: Ben Zhang <benzh@chromium.org> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
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@ -135,25 +135,27 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
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return prz;
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}
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static void ramoops_read_kmsg_hdr(char *buffer, struct timespec *time,
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static int ramoops_read_kmsg_hdr(char *buffer, struct timespec *time,
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bool *compressed)
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{
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char data_type;
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int header_length = 0;
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if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n",
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&time->tv_sec, &time->tv_nsec, &data_type) == 3) {
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if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n%n", &time->tv_sec,
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&time->tv_nsec, &data_type, &header_length) == 3) {
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if (data_type == 'C')
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*compressed = true;
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else
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*compressed = false;
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} else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu\n",
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&time->tv_sec, &time->tv_nsec) == 2) {
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} else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu\n%n",
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&time->tv_sec, &time->tv_nsec, &header_length) == 2) {
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*compressed = false;
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} else {
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time->tv_sec = 0;
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time->tv_nsec = 0;
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*compressed = false;
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}
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return header_length;
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}
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static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
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@ -165,6 +167,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
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ssize_t ecc_notice_size;
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struct ramoops_context *cxt = psi->data;
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struct persistent_ram_zone *prz;
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int header_length;
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prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt,
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cxt->max_dump_cnt, id, type,
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@ -178,7 +181,13 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
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if (!prz)
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return 0;
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if (!persistent_ram_old(prz))
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return 0;
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size = persistent_ram_old_size(prz);
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header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz), time,
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compressed);
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size -= header_length;
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/* ECC correction notice */
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ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
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@ -187,8 +196,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
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if (*buf == NULL)
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return -ENOMEM;
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memcpy(*buf, persistent_ram_old(prz), size);
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ramoops_read_kmsg_hdr(*buf, time, compressed);
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memcpy(*buf, (char *)persistent_ram_old(prz) + header_length, size);
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persistent_ram_ecc_string(prz, *buf + size, ecc_notice_size + 1);
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return size + ecc_notice_size;
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