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FROMGIT: procfs: prevent unpriveleged processes accessing fdinfo dir

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The file permissions on the fdinfo dir from were changed from
S_IRUSR|S_IXUSR to S_IRUGO|S_IXUGO, and a PTRACE_MODE_READ check was added
for opening the fdinfo files [1].  However, the ptrace permission check
was not added to the directory, allowing anyone to get the open FD numbers
by reading the fdinfo directory.

Add the missing ptrace permission check for opening the fdinfo directory.

[1] https://lkml.kernel.org/r/20210308170651.919148-1-kaleshsingh@google.com

Link: https://lkml.kernel.org/r/20210713162008.1056986-1-kaleshsingh@google.com
Fixes: 7bc3fa0172 ("procfs: allow reading fdinfo with PTRACE_MODE_READ")
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

Bug: 151772539
Change-Id: I274b30aa0a5ce8412eae7161d31c6ee955035da9
(cherry picked from commit fc73829fa54b0c7af32d6da7c972eb3390957da4
 git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master)
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This commit is contained in:
Kalesh Singh 2021-07-29 15:52:49 +01:00
commit 36fbb55631
1 changed files with 22 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

23
fs/proc/fd.c
View file

@ -71,7 +71,7 @@ out:
return 0;
}
static int seq_fdinfo_open(struct inode *inode, struct file *file)
static int proc_fdinfo_access_allowed(struct inode *inode)
{
bool allowed = false;
struct task_struct *task = get_proc_task(inode);
@ -85,6 +85,16 @@ static int seq_fdinfo_open(struct inode *inode, struct file *file)
if (!allowed)
return -EACCES;
return 0;
}
static int seq_fdinfo_open(struct inode *inode, struct file *file)
{
int ret = proc_fdinfo_access_allowed(inode);
if (ret)
return ret;
return single_open(file, seq_show, inode);
}
@ -365,12 +375,23 @@ static int proc_readfdinfo(struct file *file, struct dir_context *ctx)
proc_fdinfo_instantiate);
}
static int proc_open_fdinfo(struct inode *inode, struct file *file)
{
int ret = proc_fdinfo_access_allowed(inode);
if (ret)
return ret;
return 0;
}
const struct inode_operations proc_fdinfo_inode_operations = {
.lookup = proc_lookupfdinfo,
.setattr = proc_setattr,
};
const struct file_operations proc_fdinfo_operations = {
.open = proc_open_fdinfo,
.read = generic_read_dir,
.iterate_shared = proc_readfdinfo,
.llseek = generic_file_llseek,