Re: [PATCH v8 2/3] mm: add a field to store names for private anonymous memory
From: Michal Hocko <mhocko@suse.com>
Date: 2021-09-01 08:09:30
Also in:
linux-fsdevel, linux-mm, lkml
On Fri 27-08-21 12:18:57, Suren Baghdasaryan wrote: [...]
Userspace can set the name for a region of memory by calling prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name); Setting the name to NULL clears it.
Maybe I am missing this part but I do not see this being handled anywhere. [...]
quoted hunk ↗ jump to hunk
@@ -3283,5 +3283,16 @@ static inline int seal_check_future_write(int seals, struct vm_area_struct *vma) return 0; } +#ifdef CONFIG_ADVISE_SYSCALLS +int madvise_set_anon_name(struct mm_struct *mm, unsigned long start, + unsigned long len_in, const char *name); +#else +static inline int +madvise_set_anon_name(struct mm_struct *mm, unsigned long start, + unsigned long len_in, const char *name) { + return 0; +} +#endif
You want to make this depend on CONFIG_PROC_FS. [...]
quoted hunk ↗ jump to hunk
+#ifdef CONFIG_MMU + +#define ANON_VMA_NAME_MAX_LEN 64 + +static int prctl_set_vma(unsigned long opt, unsigned long addr, + unsigned long size, unsigned long arg) +{ + struct mm_struct *mm = current->mm; + char *name, *pch; + int error; + + switch (opt) { + case PR_SET_VMA_ANON_NAME: + name = strndup_user((const char __user *)arg, + ANON_VMA_NAME_MAX_LEN); + + if (IS_ERR(name)) + return PTR_ERR(name);
unless I am missing something NULL name would lead to an error rather than a name clearing as advertised above.
quoted hunk ↗ jump to hunk
+ + for (pch = name; *pch != '\0'; pch++) { + if (!isprint(*pch)) { + kfree(name); + return -EINVAL; + } + } + + mmap_write_lock(mm); + error = madvise_set_anon_name(mm, addr, size, name); + mmap_write_unlock(mm); + kfree(name); + break; + default: + error = -EINVAL; + } + + return error;
-- Michal Hocko SUSE Labs