From a28726b4fb624f81d637a8afb9ea12fc16500f61 Mon Sep 17 00:00:00 2001 From: Ben Zhang Date: Thu, 30 Oct 2014 17:14:21 -0700 Subject: 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 Acked-by: Kees Cook Signed-off-by: Tony Luck --- fs/pstore/ram.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) (limited to 'fs') diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index 3b5744306ed8..ec881b312700 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -135,25 +135,27 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max, return prz; } -static void ramoops_read_kmsg_hdr(char *buffer, struct timespec *time, +static int ramoops_read_kmsg_hdr(char *buffer, struct timespec *time, bool *compressed) { char data_type; + int header_length = 0; - if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n", - &time->tv_sec, &time->tv_nsec, &data_type) == 3) { + if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu-%c\n%n", &time->tv_sec, + &time->tv_nsec, &data_type, &header_length) == 3) { if (data_type == 'C') *compressed = true; else *compressed = false; - } else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu\n", - &time->tv_sec, &time->tv_nsec) == 2) { + } else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lu.%lu\n%n", + &time->tv_sec, &time->tv_nsec, &header_length) == 2) { *compressed = false; } else { time->tv_sec = 0; time->tv_nsec = 0; *compressed = false; } + return header_length; } static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, @@ -165,6 +167,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, ssize_t ecc_notice_size; struct ramoops_context *cxt = psi->data; struct persistent_ram_zone *prz; + int header_length; prz = ramoops_get_next_prz(cxt->przs, &cxt->dump_read_cnt, cxt->max_dump_cnt, id, type, @@ -178,7 +181,13 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, if (!prz) return 0; + if (!persistent_ram_old(prz)) + return 0; + size = persistent_ram_old_size(prz); + header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz), time, + compressed); + size -= header_length; /* ECC correction notice */ ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0); @@ -187,8 +196,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, if (*buf == NULL) return -ENOMEM; - memcpy(*buf, persistent_ram_old(prz), size); - ramoops_read_kmsg_hdr(*buf, time, compressed); + memcpy(*buf, (char *)persistent_ram_old(prz) + header_length, size); persistent_ram_ecc_string(prz, *buf + size, ecc_notice_size + 1); return size + ecc_notice_size; -- cgit v1.2.3-58-ga151 From 68c4a4f8abc60c9440ede9cd123d48b78325f7a3 Mon Sep 17 00:00:00 2001 From: Sebastian Schmidt Date: Sun, 19 Oct 2014 20:05:15 +0200 Subject: pstore: Honor dmesg_restrict sysctl on dmesg dumps When the kernel.dmesg_restrict restriction is in place, only users with CAP_SYSLOG should be able to access crash dumps (like: attacker is trying to exploit a bug, watchdog reboots, attacker can happily read crash dumps and logs). This puts the restriction on console-* types as well as sensitive information could have been leaked there. Other log types are unaffected. Signed-off-by: Sebastian Schmidt Acked-by: Kees Cook Signed-off-by: Tony Luck --- fs/pstore/inode.c | 22 ++++++++++++++++++++++ include/linux/syslog.h | 1 + kernel/printk/printk.c | 2 +- 3 files changed, 24 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c index fafb7a02a5d6..50416602774d 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -36,6 +36,7 @@ #include #include #include +#include #include "internal.h" @@ -120,6 +121,18 @@ static const struct seq_operations pstore_ftrace_seq_ops = { .show = pstore_ftrace_seq_show, }; +static int pstore_check_syslog_permissions(struct pstore_private *ps) +{ + switch (ps->type) { + case PSTORE_TYPE_DMESG: + case PSTORE_TYPE_CONSOLE: + return check_syslog_permissions(SYSLOG_ACTION_READ_ALL, + SYSLOG_FROM_READER); + default: + return 0; + } +} + static ssize_t pstore_file_read(struct file *file, char __user *userbuf, size_t count, loff_t *ppos) { @@ -138,6 +151,10 @@ static int pstore_file_open(struct inode *inode, struct file *file) int err; const struct seq_operations *sops = NULL; + err = pstore_check_syslog_permissions(ps); + if (err) + return err; + if (ps->type == PSTORE_TYPE_FTRACE) sops = &pstore_ftrace_seq_ops; @@ -174,6 +191,11 @@ static const struct file_operations pstore_file_operations = { static int pstore_unlink(struct inode *dir, struct dentry *dentry) { struct pstore_private *p = dentry->d_inode->i_private; + int err; + + err = pstore_check_syslog_permissions(p); + if (err) + return err; if (p->psi->erase) p->psi->erase(p->type, p->id, p->count, diff --git a/include/linux/syslog.h b/include/linux/syslog.h index 98a3153c0f96..9def5297dbb7 100644 --- a/include/linux/syslog.h +++ b/include/linux/syslog.h @@ -48,5 +48,6 @@ #define SYSLOG_FROM_PROC 1 int do_syslog(int type, char __user *buf, int count, bool from_file); +int check_syslog_permissions(int type, bool from_file); #endif /* _LINUX_SYSLOG_H */ diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index ced2b84b1cb7..c8755e7e1dba 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -480,7 +480,7 @@ static int syslog_action_restricted(int type) type != SYSLOG_ACTION_SIZE_BUFFER; } -static int check_syslog_permissions(int type, bool from_file) +int check_syslog_permissions(int type, bool from_file) { /* * If this is from /proc/kmsg and we've already opened it, then we've -- cgit v1.2.3-58-ga151