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author | Roland McGrath <roland@redhat.com> | 2008-04-29 10:01:38 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 17:06:17 +0200 |
commit | 638fa202cdb207083a12d6f73e313605a8fc1037 (patch) | |
tree | e049d74e9f7e15a55149dc17482572c8b2aefa18 /fs/proc | |
parent | proc: switch to proc_create() (diff) | |
download | linux-638fa202cdb207083a12d6f73e313605a8fc1037.tar.xz linux-638fa202cdb207083a12d6f73e313605a8fc1037.zip |
procfs: mem permission cleanup
This cleans up the permission checks done for /proc/PID/mem i/o calls. It
puts all the logic in a new function, check_mem_permission().
The old code repeated the (!MAY_PTRACE(task) || !ptrace_may_attach(task))
magical expression multiple times. The new function does all that work in one
place, with clear comments.
The old code called security_ptrace() twice on successful checks, once in
MAY_PTRACE() and once in __ptrace_may_attach(). Now it's only called once,
and only if all other checks have succeeded.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/base.c | 38 |
1 files changed, 29 insertions, 9 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index b48ddb119945..fcf02f2deeba 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -195,12 +195,32 @@ static int proc_root_link(struct inode *inode, struct path *path) return result; } -#define MAY_PTRACE(task) \ - (task == current || \ - (task->parent == current && \ - (task->ptrace & PT_PTRACED) && \ - (task_is_stopped_or_traced(task)) && \ - security_ptrace(current,task) == 0)) +/* + * Return zero if current may access user memory in @task, -error if not. + */ +static int check_mem_permission(struct task_struct *task) +{ + /* + * A task can always look at itself, in case it chooses + * to use system calls instead of load instructions. + */ + if (task == current) + return 0; + + /* + * If current is actively ptrace'ing, and would also be + * permitted to freshly attach with ptrace now, permit it. + */ + if (task->parent == current && (task->ptrace & PT_PTRACED) && + task_is_stopped_or_traced(task) && + ptrace_may_attach(task)) + return 0; + + /* + * Noone else is allowed. + */ + return -EPERM; +} struct mm_struct *mm_for_maps(struct task_struct *task) { @@ -722,7 +742,7 @@ static ssize_t mem_read(struct file * file, char __user * buf, if (!task) goto out_no_task; - if (!MAY_PTRACE(task) || !ptrace_may_attach(task)) + if (check_mem_permission(task)) goto out; ret = -ENOMEM; @@ -748,7 +768,7 @@ static ssize_t mem_read(struct file * file, char __user * buf, this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count; retval = access_process_vm(task, src, page, this_len, 0); - if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) { + if (!retval || check_mem_permission(task)) { if (!ret) ret = -EIO; break; @@ -792,7 +812,7 @@ static ssize_t mem_write(struct file * file, const char __user *buf, if (!task) goto out_no_task; - if (!MAY_PTRACE(task) || !ptrace_may_attach(task)) + if (check_mem_permission(task)) goto out; copied = -ENOMEM; |