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UPSTREAM: procfs: prevent unprivileged 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

Bug: 254441685
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: 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>
(cherry picked from commit 1927e498ae)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Idaeffb84ce297c0a393652325c74ddd533ffcfbf
This commit is contained in:
Kalesh Singh
2022-05-09 17:34:28 -07:00
committed by Treehugger Robot
parent ae1f81f7f4
commit 9257ade3bc
1 changed files with 22 additions and 1 deletions
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23
fs/proc/fd.c
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@@ -71,7 +71,7 @@ out:
return 0; 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; bool allowed = false;
struct task_struct *task = get_proc_task(inode); 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) if (!allowed)
return -EACCES; 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); 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); 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 = { const struct inode_operations proc_fdinfo_inode_operations = {
.lookup = proc_lookupfdinfo, .lookup = proc_lookupfdinfo,
.setattr = proc_setattr, .setattr = proc_setattr,
}; };
const struct file_operations proc_fdinfo_operations = { const struct file_operations proc_fdinfo_operations = {
.open = proc_open_fdinfo,
.read = generic_read_dir, .read = generic_read_dir,
.iterate_shared = proc_readfdinfo, .iterate_shared = proc_readfdinfo,
.llseek = generic_file_llseek, .llseek = generic_file_llseek,