ipc, msg: Use dedicated slab buckets for alloc_msg()
The msg subsystem is a common target for exploiting[1][2][3][4][5][6][7] use-after-free type confusion flaws in the kernel for both read and write primitives. Avoid having a user-controlled dynamically-size allocation share the global kmalloc cache by using a separate set of kmalloc buckets via the kmem_buckets API. Link: https://blog.hacktivesecurity.com/index.php/2022/06/13/linux-kernel-exploit-development-1day-case-study/ [1] Link: https://hardenedvault.net/blog/2022-11-13-msg_msg-recon-mitigation-ved/ [2] Link: https://www.willsroot.io/2021/08/corctf-2021-fire-of-salvation-writeup.html [3] Link: https://a13xp0p0v.github.io/2021/02/09/CVE-2021-26708.html [4] Link: https://google.github.io/security-research/pocs/linux/cve-2021-22555/writeup.html [5] Link: https://zplin.me/papers/ELOISE.pdf [6] Link: https://syst3mfailure.io/wall-of-perdition/ [7] Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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@ -42,6 +42,17 @@ struct msg_msgseg {
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#define DATALEN_MSG ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
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#define DATALEN_MSG ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
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#define DATALEN_SEG ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
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#define DATALEN_SEG ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))
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static kmem_buckets *msg_buckets __ro_after_init;
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static int __init init_msg_buckets(void)
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{
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msg_buckets = kmem_buckets_create("msg_msg", SLAB_ACCOUNT,
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sizeof(struct msg_msg),
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DATALEN_MSG, NULL);
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return 0;
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}
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subsys_initcall(init_msg_buckets);
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static struct msg_msg *alloc_msg(size_t len)
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static struct msg_msg *alloc_msg(size_t len)
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{
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{
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@ -50,7 +61,7 @@ static struct msg_msg *alloc_msg(size_t len)
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size_t alen;
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size_t alen;
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alen = min(len, DATALEN_MSG);
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alen = min(len, DATALEN_MSG);
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msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
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msg = kmem_buckets_alloc(msg_buckets, sizeof(*msg) + alen, GFP_KERNEL);
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if (msg == NULL)
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if (msg == NULL)
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return NULL;
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return NULL;
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