android: logger: Allow a UID to read it's own log entries
staging: logger: hold mutex while removing reader staging: android: logger: clarify non-update of w_off in do_write_log_from_user staging: android: logger: clarify code in clock_interval staging: android: logger: reorder prepare_to_wait and mutex_lock staging: android: logger: simplify and optimize get_entry_len staging: android: logger: Change logger_offset() from macro to function Staging: android: fixed white spaces coding style issue in logger.c android: logger: bump up the logger buffer sizes
This commit is contained in:
securecrt
parent
9f70587067
commit
a8ff4f89b4
@ -37,7 +37,7 @@
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* mutex 'mutex'.
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*/
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struct logger_log {
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unsigned char *buffer;/* the ring buffer itself */
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unsigned char *buffer;/* the ring buffer itself */
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struct miscdevice misc; /* misc device representing the log */
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wait_queue_head_t wq; /* wait queue for readers */
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struct list_head readers; /* this log's readers */
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@ -57,19 +57,25 @@ struct logger_reader {
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struct logger_log *log; /* associated log */
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struct list_head list; /* entry in logger_log's list */
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size_t r_off; /* current read head offset */
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bool r_all; /* reader can read all entries */
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int r_ver; /* reader ABI version */
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};
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/* logger_offset - returns index 'n' into the log via (optimized) modulus */
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#define logger_offset(n) ((n) & (log->size - 1))
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size_t logger_offset(struct logger_log *log, size_t n)
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{
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return n & (log->size-1);
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}
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/*
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* file_get_log - Given a file structure, return the associated log
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*
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* This isn't aesthetic. We have several goals:
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*
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* 1) Need to quickly obtain the associated log during an I/O operation
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* 2) Readers need to maintain state (logger_reader)
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* 3) Writers need to be very fast (open() should be a near no-op)
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* 1) Need to quickly obtain the associated log during an I/O operation
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* 2) Readers need to maintain state (logger_reader)
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* 3) Writers need to be very fast (open() should be a near no-op)
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*
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* In the reader case, we can trivially go file->logger_reader->logger_log.
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* For a writer, we don't want to maintain a logger_reader, so we just go
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@ -86,25 +92,75 @@ static inline struct logger_log *file_get_log(struct file *file)
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}
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/*
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* get_entry_len - Grabs the length of the payload of the next entry starting
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* from 'off'.
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* get_entry_header - returns a pointer to the logger_entry header within
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* 'log' starting at offset 'off'. A temporary logger_entry 'scratch' must
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* be provided. Typically the return value will be a pointer within
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* 'logger->buf'. However, a pointer to 'scratch' may be returned if
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* the log entry spans the end and beginning of the circular buffer.
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*/
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static struct logger_entry *get_entry_header(struct logger_log *log,
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size_t off, struct logger_entry *scratch)
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{
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size_t len = min(sizeof(struct logger_entry), log->size - off);
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if (len != sizeof(struct logger_entry)) {
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memcpy(((void *) scratch), log->buffer + off, len);
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memcpy(((void *) scratch) + len, log->buffer,
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sizeof(struct logger_entry) - len);
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return scratch;
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}
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return (struct logger_entry *) (log->buffer + off);
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}
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/*
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* get_entry_msg_len - Grabs the length of the message of the entry
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* starting from from 'off'.
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*
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* An entry length is 2 bytes (16 bits) in host endian order.
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* In the log, the length does not include the size of the log entry structure.
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* This function returns the size including the log entry structure.
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*
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* Caller needs to hold log->mutex.
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*/
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static __u32 get_entry_len(struct logger_log *log, size_t off)
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static __u32 get_entry_msg_len(struct logger_log *log, size_t off)
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{
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__u16 val;
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struct logger_entry scratch;
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struct logger_entry *entry;
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switch (log->size - off) {
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case 1:
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memcpy(&val, log->buffer + off, 1);
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memcpy(((char *) &val) + 1, log->buffer, 1);
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break;
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default:
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memcpy(&val, log->buffer + off, 2);
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entry = get_entry_header(log, off, &scratch);
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return entry->len;
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}
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static size_t get_user_hdr_len(int ver)
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{
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if (ver < 2)
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return sizeof(struct user_logger_entry_compat);
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else
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return sizeof(struct logger_entry);
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}
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static ssize_t copy_header_to_user(int ver, struct logger_entry *entry,
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char __user *buf)
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{
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void *hdr;
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size_t hdr_len;
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struct user_logger_entry_compat v1;
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if (ver < 2) {
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v1.len = entry->len;
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v1.__pad = 0;
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v1.pid = entry->pid;
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v1.tid = entry->tid;
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v1.sec = entry->sec;
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v1.nsec = entry->nsec;
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hdr = &v1;
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hdr_len = sizeof(struct user_logger_entry_compat);
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} else {
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hdr = entry;
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hdr_len = sizeof(struct logger_entry);
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}
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return sizeof(struct logger_entry) + val;
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return copy_to_user(buf, hdr, hdr_len);
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}
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/*
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@ -118,15 +174,31 @@ static ssize_t do_read_log_to_user(struct logger_log *log,
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char __user *buf,
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size_t count)
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{
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struct logger_entry scratch;
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struct logger_entry *entry;
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size_t len;
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size_t msg_start;
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/*
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* We read from the log in two disjoint operations. First, we read from
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* the current read head offset up to 'count' bytes or to the end of
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* First, copy the header to userspace, using the version of
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* the header requested
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*/
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entry = get_entry_header(log, reader->r_off, &scratch);
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if (copy_header_to_user(reader->r_ver, entry, buf))
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return -EFAULT;
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count -= get_user_hdr_len(reader->r_ver);
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buf += get_user_hdr_len(reader->r_ver);
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msg_start = logger_offset(log,
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reader->r_off + sizeof(struct logger_entry));
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/*
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* We read from the msg in two disjoint operations. First, we read from
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* the current msg head offset up to 'count' bytes or to the end of
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* the log, whichever comes first.
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*/
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len = min(count, log->size - reader->r_off);
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if (copy_to_user(buf, log->buffer + reader->r_off, len))
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len = min(count, log->size - msg_start);
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if (copy_to_user(buf, log->buffer + msg_start, len))
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return -EFAULT;
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/*
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@ -137,9 +209,34 @@ static ssize_t do_read_log_to_user(struct logger_log *log,
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if (copy_to_user(buf + len, log->buffer, count - len))
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return -EFAULT;
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reader->r_off = logger_offset(reader->r_off + count);
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reader->r_off = logger_offset(log, reader->r_off +
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sizeof(struct logger_entry) + count);
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return count;
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return count + get_user_hdr_len(reader->r_ver);
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}
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/*
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* get_next_entry_by_uid - Starting at 'off', returns an offset into
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* 'log->buffer' which contains the first entry readable by 'euid'
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*/
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static size_t get_next_entry_by_uid(struct logger_log *log,
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size_t off, uid_t euid)
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{
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while (off != log->w_off) {
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struct logger_entry *entry;
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struct logger_entry scratch;
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size_t next_len;
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entry = get_entry_header(log, off, &scratch);
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if (entry->euid == euid)
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return off;
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next_len = sizeof(struct logger_entry) + entry->len;
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off = logger_offset(log, off + next_len);
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}
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return off;
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}
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/*
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@ -147,11 +244,11 @@ static ssize_t do_read_log_to_user(struct logger_log *log,
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*
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* Behavior:
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*
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* - O_NONBLOCK works
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* - If there are no log entries to read, blocks until log is written to
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* - Atomically reads exactly one log entry
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* - O_NONBLOCK works
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* - If there are no log entries to read, blocks until log is written to
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* - Atomically reads exactly one log entry
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*
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* Optimal read size is LOGGER_ENTRY_MAX_LEN. Will set errno to EINVAL if read
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* Will set errno to EINVAL if read
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* buffer is insufficient to hold next entry.
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*/
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static ssize_t logger_read(struct file *file, char __user *buf,
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@ -164,9 +261,10 @@ static ssize_t logger_read(struct file *file, char __user *buf,
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start:
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while (1) {
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mutex_lock(&log->mutex);
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prepare_to_wait(&log->wq, &wait, TASK_INTERRUPTIBLE);
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mutex_lock(&log->mutex);
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ret = (log->w_off == reader->r_off);
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mutex_unlock(&log->mutex);
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if (!ret)
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@ -191,6 +289,10 @@ start:
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mutex_lock(&log->mutex);
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if (!reader->r_all)
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reader->r_off = get_next_entry_by_uid(log,
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reader->r_off, current_euid());
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/* is there still something to read or did we race? */
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if (unlikely(log->w_off == reader->r_off)) {
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mutex_unlock(&log->mutex);
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@ -198,7 +300,8 @@ start:
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}
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/* get the size of the next entry */
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ret = get_entry_len(log, reader->r_off);
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ret = get_user_hdr_len(reader->r_ver) +
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get_entry_msg_len(log, reader->r_off);
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if (count < ret) {
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ret = -EINVAL;
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goto out;
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@ -224,8 +327,9 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len)
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size_t count = 0;
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do {
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size_t nr = get_entry_len(log, off);
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off = logger_offset(off + nr);
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size_t nr = sizeof(struct logger_entry) +
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get_entry_msg_len(log, off);
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off = logger_offset(log, off + nr);
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count += nr;
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} while (count < len);
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@ -233,16 +337,28 @@ static size_t get_next_entry(struct logger_log *log, size_t off, size_t len)
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}
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/*
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* clock_interval - is a < c < b in mod-space? Put another way, does the line
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* from a to b cross c?
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* is_between - is a < c < b, accounting for wrapping of a, b, and c
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* positions in the buffer
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*
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* That is, if a<b, check for c between a and b
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* and if a>b, check for c outside (not between) a and b
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*
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* |------- a xxxxxxxx b --------|
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* c^
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*
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* |xxxxx b --------- a xxxxxxxxx|
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* c^
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* or c^
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*/
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static inline int clock_interval(size_t a, size_t b, size_t c)
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static inline int is_between(size_t a, size_t b, size_t c)
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{
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if (b < a) {
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if (a < c || b >= c)
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if (a < b) {
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/* is c between a and b? */
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if (a < c && c <= b)
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return 1;
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} else {
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if (a < c && b >= c)
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/* is c outside of b through a? */
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if (c <= b || a < c)
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return 1;
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}
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@ -260,14 +376,14 @@ static inline int clock_interval(size_t a, size_t b, size_t c)
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static void fix_up_readers(struct logger_log *log, size_t len)
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{
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size_t old = log->w_off;
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size_t new = logger_offset(old + len);
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size_t new = logger_offset(log, old + len);
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struct logger_reader *reader;
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if (clock_interval(old, new, log->head))
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if (is_between(old, new, log->head))
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log->head = get_next_entry(log, log->head, len);
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list_for_each_entry(reader, &log->readers, list)
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if (clock_interval(old, new, reader->r_off))
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if (is_between(old, new, reader->r_off))
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reader->r_off = get_next_entry(log, reader->r_off, len);
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}
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@ -286,7 +402,7 @@ static void do_write_log(struct logger_log *log, const void *buf, size_t count)
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if (count != len)
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memcpy(log->buffer, buf + len, count - len);
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log->w_off = logger_offset(log->w_off + count);
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log->w_off = logger_offset(log, log->w_off + count);
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}
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@ -309,9 +425,15 @@ static ssize_t do_write_log_from_user(struct logger_log *log,
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if (count != len)
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if (copy_from_user(log->buffer, buf + len, count - len))
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/*
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* Note that by not updating w_off, this abandons the
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* portion of the new entry that *was* successfully
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* copied, just above. This is intentional to avoid
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* message corruption from missing fragments.
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*/
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return -EFAULT;
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log->w_off = logger_offset(log->w_off + count);
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log->w_off = logger_offset(log, log->w_off + count);
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return count;
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}
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@ -336,7 +458,9 @@ ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov,
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header.tid = current->pid;
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header.sec = now.tv_sec;
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header.nsec = now.tv_nsec;
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header.euid = current_euid();
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header.len = min_t(size_t, iocb->ki_left, LOGGER_ENTRY_MAX_PAYLOAD);
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header.hdr_size = sizeof(struct logger_entry);
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/* null writes succeed, return zero */
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if (unlikely(!header.len))
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@ -409,6 +533,10 @@ static int logger_open(struct inode *inode, struct file *file)
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return -ENOMEM;
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reader->log = log;
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reader->r_ver = 1;
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reader->r_all = in_egroup_p(inode->i_gid) ||
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capable(CAP_SYSLOG);
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INIT_LIST_HEAD(&reader->list);
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mutex_lock(&log->mutex);
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@ -433,9 +561,11 @@ static int logger_release(struct inode *ignored, struct file *file)
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if (file->f_mode & FMODE_READ) {
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struct logger_reader *reader = file->private_data;
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struct logger_log *log = reader->log;
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mutex_lock(&log->mutex);
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list_del(&reader->list);
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mutex_unlock(&log->mutex);
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kfree(reader);
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}
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@ -466,6 +596,10 @@ static unsigned int logger_poll(struct file *file, poll_table *wait)
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poll_wait(file, &log->wq, wait);
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mutex_lock(&log->mutex);
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if (!reader->r_all)
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reader->r_off = get_next_entry_by_uid(log,
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reader->r_off, current_euid());
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if (log->w_off != reader->r_off)
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ret |= POLLIN | POLLRDNORM;
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mutex_unlock(&log->mutex);
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@ -473,11 +607,25 @@ static unsigned int logger_poll(struct file *file, poll_table *wait)
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return ret;
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}
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static long logger_set_version(struct logger_reader *reader, void __user *arg)
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{
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int version;
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if (copy_from_user(&version, arg, sizeof(int)))
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return -EFAULT;
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if ((version < 1) || (version > 2))
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return -EINVAL;
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reader->r_ver = version;
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return 0;
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}
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static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct logger_log *log = file_get_log(file);
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struct logger_reader *reader;
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long ret = -ENOTTY;
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long ret = -EINVAL;
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void __user *argp = (void __user *) arg;
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mutex_lock(&log->mutex);
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@ -502,8 +650,14 @@ static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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break;
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}
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reader = file->private_data;
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if (!reader->r_all)
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reader->r_off = get_next_entry_by_uid(log,
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reader->r_off, current_euid());
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if (log->w_off != reader->r_off)
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ret = get_entry_len(log, reader->r_off);
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ret = get_user_hdr_len(reader->r_ver) +
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get_entry_msg_len(log, reader->r_off);
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else
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ret = 0;
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break;
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@ -517,6 +671,22 @@ static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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log->head = log->w_off;
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ret = 0;
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break;
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case LOGGER_GET_VERSION:
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if (!(file->f_mode & FMODE_READ)) {
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ret = -EBADF;
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break;
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}
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reader = file->private_data;
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ret = reader->r_ver;
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break;
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case LOGGER_SET_VERSION:
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if (!(file->f_mode & FMODE_READ)) {
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ret = -EBADF;
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break;
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}
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reader = file->private_data;
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ret = logger_set_version(reader, argp);
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break;
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}
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mutex_unlock(&log->mutex);
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@ -537,8 +707,8 @@ static const struct file_operations logger_fops = {
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/*
|
||||
* Defines a log structure with name 'NAME' and a size of 'SIZE' bytes, which
|
||||
* must be a power of two, greater than LOGGER_ENTRY_MAX_LEN, and less than
|
||||
* LONG_MAX minus LOGGER_ENTRY_MAX_LEN.
|
||||
* must be a power of two, and greater than
|
||||
* (LOGGER_ENTRY_MAX_PAYLOAD + sizeof(struct logger_entry)).
|
||||
*/
|
||||
#define DEFINE_LOGGER_DEVICE(VAR, NAME, SIZE) \
|
||||
static unsigned char _buf_ ## VAR[SIZE]; \
|
||||
|
||||
@ -20,7 +20,12 @@
|
||||
#include <linux/types.h>
|
||||
#include <linux/ioctl.h>
|
||||
|
||||
struct logger_entry {
|
||||
/*
|
||||
* 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 user_logger_entry_compat {
|
||||
__u16 len; /* length of the payload */
|
||||
__u16 __pad; /* no matter what, we get 2 bytes of padding */
|
||||
__s32 pid; /* generating process's pid */
|
||||
@ -30,14 +35,28 @@ struct logger_entry {
|
||||
char msg[0]; /* the entry's payload */
|
||||
};
|
||||
|
||||
/*
|
||||
* 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; /* length of the payload */
|
||||
__u16 hdr_size; /* sizeof(struct logger_entry_v2) */
|
||||
__s32 pid; /* generating process's pid */
|
||||
__s32 tid; /* generating process's tid */
|
||||
__s32 sec; /* seconds since Epoch */
|
||||
__s32 nsec; /* nanoseconds */
|
||||
uid_t euid; /* effective UID of logger */
|
||||
char msg[0]; /* the entry's payload */
|
||||
};
|
||||
|
||||
#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
|
||||
|
||||
@ -45,5 +64,7 @@ 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 */
|
||||
|
||||
@ -357,7 +357,11 @@ struct cpu_vfs_cap_data {
|
||||
|
||||
#define CAP_MAC_ADMIN 33
|
||||
|
||||
#define CAP_LAST_CAP CAP_MAC_ADMIN
|
||||
/* Allow configuring the kernel's syslog (printk behaviour) */
|
||||
|
||||
#define CAP_SYSLOG 34
|
||||
|
||||
#define CAP_LAST_CAP CAP_SYSLOG
|
||||
|
||||
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
|
||||
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user