From: Kalesh Singh Date: Thu, 23 Jun 2022 22:06:06 +0000 (-0700) Subject: procfs: add 'size' to /proc//fdinfo/ X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1ad84294dd040f625febc9dc9a565ba687ffe90f;p=users%2Fjedix%2Flinux-maple.git procfs: add 'size' to /proc//fdinfo/ Patch series "procfs: Add file path and size to /proc//fdinfo", v2. Processes can pin shared memory by keeping a handle to it through a file descriptor; for instance dmabufs, memfd, and ashmem (in Android). In the case of a memory leak, to identify the process pinning the memory, userspace needs to: - Iterate the /proc//fd/* for each process - Do a readlink on each entry to identify the type of memory from the file path. - stat() each entry to get the size of the memory. The file permissions on /proc//fd/* only allows for the owner or root to perform the operations above; and so is not suitable for capturing the system-wide state in a production environment. This issue was addressed for dmabufs by making /proc/*/fdinfo/* accessible to a process with PTRACE_MODE_READ_FSCREDS credentials[1] To allow the same kind of tracking for other types of shared memory, add the following fields to /proc//fdinfo/: path - This allows identifying the type of memory based on common prefixes: e.g. "/memfd...", "/dmabuf...", "/dev/ashmem..." This was not an issued when dmabuf tracking was introduced because the exp_name field of dmabuf fdinfo could be used to distinguish dmabuf fds from other types. size - To track the amount of memory that is being pinned. dmabufs expose size as an additional field in fdinfo. Remove this and make it a common field for all fds. Access to /proc//fdinfo is governed by PTRACE_MODE_READ_FSCREDS -- the same as for /proc//maps which also exposes the path and size for mapped memory regions. This allows for a system process with PTRACE_MODE_READ_FSCREDS to account the pinned per-process memory via fdinfo. This patch (of 2): To be able to account the amount of memory a process is keeping pinned by open file descriptors add a 'size' field to fdinfo output. dmabufs fds already expose a 'size' field for this reason, remove this and make it a common field for all fds. This allows tracking of other types of memory (e.g. memfd and ashmem in Android). Link: https://lkml.kernel.org/r/20220623220613.3014268-1-kaleshsingh@google.com Link: https://lkml.kernel.org/r/20220623220613.3014268-2-kaleshsingh@google.com Signed-off-by: Kalesh Singh Reviewed-by: Christian König Cc: Al Viro Cc: Christoph Hellwig Cc: Stephen Brennan Cc: David Laight Cc: Ioannis Ilkos Cc: T.J. Mercier Cc: Suren Baghdasaryan Cc: Jonathan Corbet Cc: Sumit Semwal Cc: Johannes Weiner Cc: Christoph Anton Mitterer Cc: Colin Cross Cc: Paul Gortmaker Cc: Randy Dunlap Cc: Alexey Dobriyan Signed-off-by: Andrew Morton --- diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index e7aafc82be99..640fe47586e3 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -1891,13 +1891,14 @@ if precise results are needed. 3.8 /proc//fdinfo/ - Information about opened file --------------------------------------------------------------- This file provides information associated with an opened file. The regular -files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'. +files have at least five fields -- 'pos', 'flags', 'mnt_id', 'ino', and 'size'. + The 'pos' represents the current offset of the opened file in decimal form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the file has been created with [see open(2) for details] and 'mnt_id' represents mount ID of the file system containing the opened file [see 3.5 /proc//mountinfo for details]. 'ino' represents the inode number of -the file. +the file, and 'size' represents the size of the file in bytes. A typical output is:: @@ -1905,6 +1906,7 @@ A typical output is:: flags: 0100002 mnt_id: 19 ino: 63107 + size: 0 All locks associated with a file descriptor are shown in its fdinfo too:: @@ -1922,6 +1924,7 @@ Eventfd files flags: 04002 mnt_id: 9 ino: 63107 + size: 0 eventfd-count: 5a where 'eventfd-count' is hex value of a counter. @@ -1935,6 +1938,7 @@ Signalfd files flags: 04002 mnt_id: 9 ino: 63107 + size: 0 sigmask: 0000000000000200 where 'sigmask' is hex value of the signal mask associated @@ -1949,6 +1953,7 @@ Epoll files flags: 02 mnt_id: 9 ino: 63107 + size: 0 tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 where 'tfd' is a target file descriptor number in decimal form, @@ -1967,6 +1972,7 @@ For inotify files the format is the following:: flags: 02000000 mnt_id: 9 ino: 63107 + size: 0 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d where 'wd' is a watch descriptor in decimal form, i.e. a target file @@ -1990,6 +1996,7 @@ For fanotify files the format is:: flags: 02 mnt_id: 9 ino: 63107 + size: 0 fanotify flags:10 event-flags:0 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4 @@ -2015,6 +2022,7 @@ Timerfd files flags: 02 mnt_id: 9 ino: 63107 + size: 0 clockid: 0 ticks: 0 settime flags: 01 diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index efb4990b29e1..44574fbe7482 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -484,7 +484,6 @@ static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file) { struct dma_buf *dmabuf = file->private_data; - seq_printf(m, "size:\t%zu\n", dmabuf->size); /* Don't count the temporary reference taken inside procfs seq_show */ seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1); seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name); diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 913bef0d2a36..464bc3f55759 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -54,10 +54,11 @@ static int seq_show(struct seq_file *m, void *v) if (ret) return ret; - seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n", - (long long)file->f_pos, f_flags, - real_mount(file->f_path.mnt)->mnt_id, - file_inode(file)->i_ino); + seq_printf(m, "pos:\t%lli\n", (long long)file->f_pos); + seq_printf(m, "flags:\t0%o\n", f_flags); + seq_printf(m, "mnt_id:\t%i\n", real_mount(file->f_path.mnt)->mnt_id); + seq_printf(m, "ino:\t%lu\n", file_inode(file)->i_ino); + seq_printf(m, "size:\t%lli\n", (long long)file_inode(file)->i_size); /* show_fd_locks() never deferences files so a stale value is safe */ show_fd_locks(m, file, files);