From 0441bcf4db64e9825937916fe64d539d12c3fead Mon Sep 17 00:00:00 2001 From: Nick Kralevich Date: Tue, 26 Feb 2013 22:07:37 -0800 Subject: [PATCH] staging: android: logger: Allow a UID to read it's own log entries Modify the kernel logger to record the UID associated with the log entries. Always allow the same UID which generated a log message to read the log message. Allow anyone in the logs group, or anyone with CAP_SYSLOG, to read all log entries. In addition, allow the client to upgrade log formats, so they can get additional information from the kernel. Cc: Android Kernel Team Cc: Nick Kralevich Signed-off-by: Nick Kralevich Signed-off-by: John Stultz Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/logger.c | 191 ++++++++++++++++++++++++++++++++++----- drivers/staging/android/logger.h | 40 +++++++- 2 files changed, 202 insertions(+), 29 deletions(-) diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c index dbc63cb..cfa6061 100644 --- a/drivers/staging/android/logger.c +++ b/drivers/staging/android/logger.c @@ -68,6 +68,8 @@ static LIST_HEAD(log_list); * @log: The associated log * @list: The associated entry in @logger_log's list * @r_off: The current read head offset. + * @r_all: Reader can read all entries + * @r_ver: Reader ABI version * * This object lives from open to release, so we don't need additional * reference counting. The structure is protected by log->mutex. @@ -76,6 +78,8 @@ struct logger_reader { struct logger_log *log; struct list_head list; size_t r_off; + bool r_all; + int r_ver; }; /* logger_offset - returns index 'n' into the log via (optimized) modulus */ @@ -109,8 +113,29 @@ static inline struct logger_log *file_get_log(struct file *file) } /* - * get_entry_len - Grabs the length of the payload of the next entry starting - * from 'off'. + * get_entry_header - returns a pointer to the logger_entry header within + * 'log' starting at offset 'off'. A temporary logger_entry 'scratch' must + * be provided. Typically the return value will be a pointer within + * 'logger->buf'. However, a pointer to 'scratch' may be returned if + * the log entry spans the end and beginning of the circular buffer. + */ +static struct logger_entry *get_entry_header(struct logger_log *log, + size_t off, struct logger_entry *scratch) +{ + size_t len = min(sizeof(struct logger_entry), log->size - off); + if (len != sizeof(struct logger_entry)) { + memcpy(((void *) scratch), log->buffer + off, len); + memcpy(((void *) scratch) + len, log->buffer, + sizeof(struct logger_entry) - len); + return scratch; + } + + return (struct logger_entry *) (log->buffer + off); +} + +/* + * get_entry_msg_len - Grabs the length of the message of the entry + * starting from from 'off'. * * An entry length is 2 bytes (16 bits) in host endian order. * In the log, the length does not include the size of the log entry structure. @@ -118,20 +143,45 @@ static inline struct logger_log *file_get_log(struct file *file) * * Caller needs to hold log->mutex. */ -static __u32 get_entry_len(struct logger_log *log, size_t off) +static __u32 get_entry_msg_len(struct logger_log *log, size_t off) { - __u16 val; + struct logger_entry scratch; + struct logger_entry *entry; - /* copy 2 bytes from buffer, in memcpy order, */ - /* handling possible wrap at end of buffer */ + entry = get_entry_header(log, off, &scratch); + return entry->len; +} - ((__u8 *)&val)[0] = log->buffer[off]; - if (likely(off+1 < log->size)) - ((__u8 *)&val)[1] = log->buffer[off+1]; +static size_t get_user_hdr_len(int ver) +{ + if (ver < 2) + return sizeof(struct user_logger_entry_compat); else - ((__u8 *)&val)[1] = log->buffer[0]; + return sizeof(struct logger_entry); +} + +static ssize_t copy_header_to_user(int ver, struct logger_entry *entry, + char __user *buf) +{ + void *hdr; + size_t hdr_len; + struct user_logger_entry_compat v1; + + if (ver < 2) { + v1.len = entry->len; + v1.__pad = 0; + v1.pid = entry->pid; + v1.tid = entry->tid; + v1.sec = entry->sec; + v1.nsec = entry->nsec; + hdr = &v1; + hdr_len = sizeof(struct user_logger_entry_compat); + } else { + hdr = entry; + hdr_len = sizeof(struct logger_entry); + } - return sizeof(struct logger_entry) + val; + return copy_to_user(buf, hdr, hdr_len); } /* @@ -145,15 +195,31 @@ static ssize_t do_read_log_to_user(struct logger_log *log, char __user *buf, size_t count) { + struct logger_entry scratch; + struct logger_entry *entry; size_t len; + size_t msg_start; /* - * We read from the log in two disjoint operations. First, we read from - * the current read head offset up to 'count' bytes or to the end of + * First, copy the header to userspace, using the version of + * the header requested + */ + entry = get_entry_header(log, reader->r_off, &scratch); + if (copy_header_to_user(reader->r_ver, entry, buf)) + return -EFAULT; + + count -= get_user_hdr_len(reader->r_ver); + buf += get_user_hdr_len(reader->r_ver); + msg_start = logger_offset(log, + reader->r_off + sizeof(struct logger_entry)); + + /* + * We read from the msg in two disjoint operations. First, we read from + * the current msg head offset up to 'count' bytes or to the end of * the log, whichever comes first. */ - len = min(count, log->size - reader->r_off); - if (copy_to_user(buf, log->buffer + reader->r_off, len)) + len = min(count, log->size - msg_start); + if (copy_to_user(buf, log->buffer + msg_start, len)) return -EFAULT; /* @@ -164,9 +230,34 @@ static ssize_t do_read_log_to_user(struct logger_log *log, if (copy_to_user(buf + len, log->buffer, count - len)) return -EFAULT; - reader->r_off = logger_offset(log, reader->r_off + count); + reader->r_off = logger_offset(log, reader->r_off + + sizeof(struct logger_entry) + count); - return count; + return count + get_user_hdr_len(reader->r_ver); +} + +/* + * get_next_entry_by_uid - Starting at 'off', returns an offset into + * 'log->buffer' which contains the first entry readable by 'euid' + */ +static size_t get_next_entry_by_uid(struct logger_log *log, + size_t off, uid_t euid) +{ + while (off != log->w_off) { + struct logger_entry *entry; + struct logger_entry scratch; + size_t next_len; + + entry = get_entry_header(log, off, &scratch); + + if (entry->euid == euid) + return off; + + next_len = sizeof(struct logger_entry) + entry->len; + off = logger_offset(log, off + next_len); + } + + return off; } /* @@ -178,7 +269,7 @@ static ssize_t do_read_log_to_user(struct logger_log *log, * - If there are no log entries to read, blocks until log is written to * - Atomically reads exactly one log entry * - * Optimal read size is LOGGER_ENTRY_MAX_LEN. Will set errno to EINVAL if read + * Will set errno to EINVAL if read * buffer is insufficient to hold next entry. */ static ssize_t logger_read(struct file *file, char __user *buf, @@ -219,6 +310,10 @@ start: mutex_lock(&log->mutex); + if (!reader->r_all) + reader->r_off = get_next_entry_by_uid(log, + reader->r_off, current_euid()); + /* is there still something to read or did we race? */ if (unlikely(log->w_off == reader->r_off)) { mutex_unlock(&log->mutex); @@ -226,7 +321,8 @@ start: } /* get the size of the next entry */ - ret = get_entry_len(log, reader->r_off); + ret = get_user_hdr_len(reader->r_ver) + + get_entry_msg_len(log, reader->r_off); if (count < ret) { ret = -EINVAL; goto out; @@ -252,7 +348,8 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len) size_t count = 0; do { - size_t nr = get_entry_len(log, off); + size_t nr = sizeof(struct logger_entry) + + get_entry_msg_len(log, off); off = logger_offset(log, off + nr); count += nr; } while (count < len); @@ -382,7 +479,9 @@ static ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov, header.tid = current->pid; header.sec = now.tv_sec; header.nsec = now.tv_nsec; + header.euid = current_euid(); header.len = min_t(size_t, iocb->ki_left, LOGGER_ENTRY_MAX_PAYLOAD); + header.hdr_size = sizeof(struct logger_entry); /* null writes succeed, return zero */ if (unlikely(!header.len)) @@ -463,6 +562,10 @@ static int logger_open(struct inode *inode, struct file *file) return -ENOMEM; reader->log = log; + reader->r_ver = 1; + reader->r_all = in_egroup_p(inode->i_gid) || + capable(CAP_SYSLOG); + INIT_LIST_HEAD(&reader->list); mutex_lock(&log->mutex); @@ -522,6 +625,10 @@ static unsigned int logger_poll(struct file *file, poll_table *wait) poll_wait(file, &log->wq, wait); mutex_lock(&log->mutex); + if (!reader->r_all) + reader->r_off = get_next_entry_by_uid(log, + reader->r_off, current_euid()); + if (log->w_off != reader->r_off) ret |= POLLIN | POLLRDNORM; mutex_unlock(&log->mutex); @@ -529,11 +636,25 @@ static unsigned int logger_poll(struct file *file, poll_table *wait) return ret; } +static long logger_set_version(struct logger_reader *reader, void __user *arg) +{ + int version; + if (copy_from_user(&version, arg, sizeof(int))) + return -EFAULT; + + if ((version < 1) || (version > 2)) + return -EINVAL; + + reader->r_ver = version; + return 0; +} + static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct logger_log *log = file_get_log(file); struct logger_reader *reader; - long ret = -ENOTTY; + long ret = -EINVAL; + void __user *argp = (void __user *) arg; mutex_lock(&log->mutex); @@ -558,8 +679,14 @@ static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg) break; } reader = file->private_data; + + if (!reader->r_all) + reader->r_off = get_next_entry_by_uid(log, + reader->r_off, current_euid()); + if (log->w_off != reader->r_off) - ret = get_entry_len(log, reader->r_off); + ret = get_user_hdr_len(reader->r_ver) + + get_entry_msg_len(log, reader->r_off); else ret = 0; break; @@ -573,6 +700,22 @@ static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg) log->head = log->w_off; ret = 0; break; + case LOGGER_GET_VERSION: + if (!(file->f_mode & FMODE_READ)) { + ret = -EBADF; + break; + } + reader = file->private_data; + ret = reader->r_ver; + break; + case LOGGER_SET_VERSION: + if (!(file->f_mode & FMODE_READ)) { + ret = -EBADF; + break; + } + reader = file->private_data; + ret = logger_set_version(reader, argp); + break; } mutex_unlock(&log->mutex); @@ -592,8 +735,8 @@ static const struct file_operations logger_fops = { }; /* - * Log size must be a power of two, greater than LOGGER_ENTRY_MAX_LEN, - * and less than LONG_MAX minus LOGGER_ENTRY_MAX_LEN. + * Log size must must be a power of two, and greater than + * (LOGGER_ENTRY_MAX_PAYLOAD + sizeof(struct logger_entry)). */ static int __init create_log(char *log_name, int size) { diff --git a/drivers/staging/android/logger.h b/drivers/staging/android/logger.h index 9b929a8..cc6bbd9 100644 --- a/drivers/staging/android/logger.h +++ b/drivers/staging/android/logger.h @@ -21,7 +21,7 @@ #include /** - * struct logger_entry - defines a single entry that is given to a logger + * struct user_logger_entry_compat - defines a single entry that is given to a logger * @len: The length of the payload * @__pad: Two bytes of padding that appear to be required * @pid: The generating process' process ID @@ -29,8 +29,12 @@ * @sec: The number of seconds that have elapsed since the Epoch * @nsec: The number of nanoseconds that have elapsed since @sec * @msg: The message that is to be logged + * + * The userspace structure for version 1 of the logger_entry ABI. + * This structure is returned to userspace unless the caller requests + * an upgrade to a newer ABI version. */ -struct logger_entry { +struct user_logger_entry_compat { __u16 len; __u16 __pad; __s32 pid; @@ -40,14 +44,38 @@ struct logger_entry { char msg[0]; }; +/** + * struct logger_entry - defines a single entry that is given to a logger + * @len: The length of the payload + * @hdr_size: sizeof(struct logger_entry_v2) + * @pid: The generating process' process ID + * @tid: The generating process' thread ID + * @sec: The number of seconds that have elapsed since the Epoch + * @nsec: The number of nanoseconds that have elapsed since @sec + * @euid: Effective UID of logger + * @msg: The message that is to be logged + * + * The structure for version 2 of the logger_entry ABI. + * This structure is returned to userspace if ioctl(LOGGER_SET_VERSION) + * is called with version >= 2 + */ +struct logger_entry { + __u16 len; + __u16 hdr_size; + __s32 pid; + __s32 tid; + __s32 sec; + __s32 nsec; + uid_t euid; + char msg[0]; +}; + #define LOGGER_LOG_RADIO "log_radio" /* radio-related messages */ #define LOGGER_LOG_EVENTS "log_events" /* system/hardware events */ #define LOGGER_LOG_SYSTEM "log_system" /* system/framework messages */ #define LOGGER_LOG_MAIN "log_main" /* everything else */ -#define LOGGER_ENTRY_MAX_LEN (4*1024) -#define LOGGER_ENTRY_MAX_PAYLOAD \ - (LOGGER_ENTRY_MAX_LEN - sizeof(struct logger_entry)) +#define LOGGER_ENTRY_MAX_PAYLOAD 4076 #define __LOGGERIO 0xAE @@ -55,5 +83,7 @@ struct logger_entry { #define LOGGER_GET_LOG_LEN _IO(__LOGGERIO, 2) /* used log len */ #define LOGGER_GET_NEXT_ENTRY_LEN _IO(__LOGGERIO, 3) /* next entry len */ #define LOGGER_FLUSH_LOG _IO(__LOGGERIO, 4) /* flush log */ +#define LOGGER_GET_VERSION _IO(__LOGGERIO, 5) /* abi version */ +#define LOGGER_SET_VERSION _IO(__LOGGERIO, 6) /* abi version */ #endif /* _LINUX_LOGGER_H */ -- 2.7.4