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Fri, 13 Sep 2024 14:51:46 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id SF6GDIJR5GbvQQAAD6G6ig (envelope-from ); Fri, 13 Sep 2024 14:51:46 +0000 Message-ID: <96cd579b-0677-40b7-974c-107c42fab7a6@suse.cz> Date: Fri, 13 Sep 2024 16:51:45 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/madvise: process_madvise() drop capability check if same mm Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Liam Howlett , Shakeel Butt , Suren Baghdasaryan References: <20240913140628.77047-1-lorenzo.stoakes@oracle.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240913140628.77047-1-lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Queue-Id: 2E84D1C0014 X-Stat-Signature: aa7dd9hkweojwit1nywrpj9qy9eugws8 X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1726239107-539689 X-HE-Meta: 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 2Yz86iQ1 uXpp7+PULO5HKJYRfiPrcI5soK/vgIlRVcc+z4MfZYauaUu3KxtHeY0o5CvY4TzjMRXaJT2NsnGz6zEDt95kklZdJQ+5SrR020hgy9cDz39NbJFVwonO31b8VMhagnM+w0gG2TreNJwrEe0J0K37d1bwrV0BTVcYpi9ZsWXPQRpa/FZFBWULchqBv3wQwhKeRl3i1iLsSXWL3BvhVRRhfhCvjvkGGzwDjV9cbvKZCb2T51GtHj9YnKAWuYKIOXVwC51Om7JF0E2CRZSvoFQKozOv+U/R2OAo50QEeeFBB1IKEUd8vvxdn2CJrAxBkAjk4kH+9ZeCvhVC5MTZcrR/cEcLHHRu1MqqTGuNV X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/13/24 16:06, Lorenzo Stoakes wrote: > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > process_madvise") process_madvise() was updated to require the caller to > possess the CAP_SYS_NICE capability to perform the operation, in addition > to a check against PTRACE_MODE_READ performed by mm_access(). > > The mm_access() function explicitly checks to see if the address space of > the process being referenced is the current one, in which case no check is > performed. > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > means that we insist on the caller possessing this capability in order to > perform madvise() operations on its own address space, which seems > nonsensical. > > Simply add a check to allow for an invocation of this function with pidfd > set to the current process without elevation. > > Signed-off-by: Lorenzo Stoakes Acked-by: Vlastimil Babka > --- > mm/madvise.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 4e64770be16c..ff139e57cca2 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1520,7 +1520,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, > * Require CAP_SYS_NICE for influencing process performance. Note that > * only non-destructive hints are currently supported. > */ > - if (!capable(CAP_SYS_NICE)) { > + if (mm != current->mm && !capable(CAP_SYS_NICE)) { > ret = -EPERM; > goto release_mm; > }